JP4374289B2 - Surface treated steel plate with excellent corrosion resistance - Google Patents

Description

The present invention relates to a plated steel sheet, and more particularly to a plated steel sheet that has excellent processed portion corrosion resistance and can be applied as a steel sheet for various uses such as home appliances, automobiles, and building materials.

One of the most commonly used plated steel materials with good corrosion resistance is galvanized steel sheet. These plated steel sheets are used in various manufacturing industries such as automobiles, home appliances, and building materials.
In particular, the use of Al-added plating has increased in recent years due to its high corrosion resistance.

  In order to improve the corrosion resistance of such galvanized steel sheets, the present inventors proposed a hot-dip Zn-Al-Mg-Si plated steel sheet in Japanese Patent No. 3179446.

For the purpose of improving the smoothness of the surface, the present inventors have disclosed a plated steel sheet to which an intermetallic compound having a high melting point is added in JP-A No. 2003-293108, and an Al-based intermetallic compound in JP-A No. 2003-328100. We proposed a galvanized steel sheet with the addition of.
Moreover, in order to give the above-mentioned and other previously disclosed plated steel sheets a higher level of rust prevention function, chromate treatment using hexavalent chromate or the like is widely performed after plating, and further if necessary. In order to provide high added value functions such as designability, stain resistance, and lubricity, coating with an organic resin is performed.

Japanese Patent No. 3179446 JP 2003-293108 A JP 2003-328100 A

  However, in the above-described and other previously disclosed plated steel sheets and coated steel sheets, the corrosion resistance of the processed parts is not sufficiently ensured.

In galvanized steel sheet with Mg added, MgZn ₂ phase crystallizes during plating. Since this MgZn ₂ phase is hard and brittle, when severe processing such as T-bending is performed on a zinc-plated steel sheet to which Mg has been added, cracks occur in the plating, and this tends to cause deterioration in corrosion resistance after processing. It has the problem that.

Even if a steel plate containing such a hard and brittle MgZn ₂ phase is coated with an organic resin, it is difficult to protect cracks generated in the plating at the processed part, so that the corrosion resistance deterioration after processing cannot be improved. is doing.

The present invention has been made in view of the above problems, a galvanized steel material MgZn ₂ phase crystallized out during the plating, and the painted galvanized steel sheet MgZn ₂ phase crystallized out in the plating It aims at improving the process part corrosion resistance of the given surface-treated steel sheet.

  In recent years, there is a movement to refrain from using chromate treatment against the background of increasing environmental problems. Therefore, one object of the present invention is to improve the processed portion corrosion resistance of the surface-treated steel sheet without performing chromate treatment.

The present inventors, as a result of superimposed intensive studies on the development of the surface-treated steel sheet processed portion corrosion resistance superior, and [Mg ₂ Si phase] in the matrix of [Al / Zn / MgZn ₂ ternary eutectic structure] [Al phase] and [MgZn ₂ phase] are mixed in the [Al phase] of the plating layer, and the lattice spacing of one of the lattice directions constituting the lattice plane of the Bravay lattice is not less than 2.57 mm and not more than 3.15 mm. Has found a new finding that the corrosion resistance of the processed part is improved by having a plating layer containing an intermetallic compound having a lattice plane with a surface spacing of 3.64 mm or more and 4.46 mm or less on the surface. New knowledge that a higher degree of corrosion resistance can be imparted by applying a base treatment on the top and applying a coating obtained by applying an aqueous resin and silica particle-optimized coating to the upper layer and drying it. Heading The present invention has been completed.

  That is, the gist of the present invention is as follows.

(1) On one side or both sides of the steel sheet, Al: 4 to 22% by mass, Mg: 1 to 5% by mass, Si: 0.5% by mass or less, and one plane spacing in the lattice direction constituting the lattice plane of the Bravay lattice Alloy composition comprising an intermetallic compound having a lattice plane in which the distance between the other planes is not less than 2.57 mm and not more than 3.15 mm and the other plane spacing is not less than 3.64 mm and not more than 4.46 mm, and the balance is composed of Zn and inevitable impurities A metallized structure in which a plated layer of a plated steel sheet having a layer is mixed with [Mg ₂ Si phase], [Al phase] and [MgZn ₂ phase] in a [Al / Zn / MgZn ₂ ternary eutectic structure] substrate And the interval between one plane in the lattice direction constituting the lattice plane of the Bravey lattice in the [Al phase] is 2.57 mm to 3.15 mm and the other plane distance is 3.64 mm to 4.46 mm. an intermetallic compound having a grating surface is less, the gold One surface interval is less 3.15Å than 2.57Å between compounds, other surface interval {110} plane of the grating surface and the Al phase is less than 4.46Å than 3.64Å contains so as to be parallel plating 5 to 50% by mass of silica particles (b) with respect to 100% by mass of the solid content of the aqueous resin (a) as an upper layer. A surface-treated steel sheet having excellent processed portion corrosion resistance, wherein a resin-based film obtained by applying and drying a water-based paint is formed with an adhesion amount of 0.2 to 5 g / m ² .

(2) On one side or both sides of the steel plate, Al: 4 to 22% by mass, Mg: 1 to 5% by mass, Si: 0.5% by mass or less, and one plane spacing in the lattice direction constituting the lattice plane of the Bravay lattice Alloy composition comprising an intermetallic compound having a lattice plane in which the distance between the other planes is not less than 2.57 mm and not more than 3.15 mm and the other plane spacing is not less than 3.64 mm and not more than 4.46 mm, and the balance is composed of Zn and inevitable impurities A metallized structure in which a plated layer of a plated steel sheet having a layer is mixed with [Mg ₂ Si phase], [Al phase] and [MgZn ₂ phase] in a [Al / Zn / MgZn ₂ ternary eutectic structure] substrate And the interval between one plane in the lattice direction constituting the lattice plane of the Bravey lattice in the [Al phase] is 2.57 mm to 3.15 mm and the other plane distance is 3.64 mm to 4.46 mm. an intermetallic compound having a grating surface is less, the gold One surface interval is less 3.15Å than 2.57Å between compounds, other surface interval {110} plane of the grating surface and the Al phase is less than 4.46Å than 3.64Å contains so as to be parallel plating 5 to 50% by mass of silica particles (b) with respect to 100% by mass of the solid content of the aqueous resin (a) as an upper layer. A surface-treated steel sheet having excellent processed portion corrosion resistance, wherein a resin-based film obtained by applying and drying a water-based paint is formed with an adhesion amount of 0.2 to 5 g / m ² .

  (3) The crystal system of the intermetallic compound according to any one of (1) to (2) is any one of cubic, tetragonal, orthorhombic, monoclinic, and hexagonal. Surface treated steel plate with excellent corrosion resistance.

  (4) A surface-treated steel sheet excellent in processed part corrosion resistance, wherein the content of the intermetallic compound according to any one of (1) to (3) is 1% by mass or less.

  (5) Intermetallic compound having a lattice plane in which the lattice spacing of one of the lattice directions constituting the lattice plane of the Bravais lattice is 2.57 mm or more and 3.15 mm or less and the other surface spacing is 3.64 mm or more and 4.46 mm or less. The surface-treated steel sheet having excellent corrosion resistance in the machined portion according to any one of (1) to (4), characterized in that the primary arm of the Al-phase dendrite grows in the [110] direction. .

  (6) The aqueous resin (a) is at least one selected from the group consisting of an aqueous epoxy resin, an aqueous phenol resin, an aqueous polyester resin, an aqueous polyurethane resin, an aqueous acrylic resin, and an aqueous polyolefin resin. A surface-treated steel sheet excellent in processed part corrosion resistance according to any one of (1) to (5).

  (7) The surface-treated steel sheet with excellent processed portion corrosion resistance according to any one of (1) to (6), wherein the aqueous resin (a) is a polyurethane resin having a polyester skeleton portion and a polyether skeleton. .

  (8) Any of the above (1) to (7), wherein the mass ratio of the polyether skeleton to the polyester skeleton of the polyurethane resin having a polyester skeleton portion and a polyether skeleton is 10:90 to 70:30 Surface treated steel sheet with excellent corrosion resistance in the processed part as described in 1.

  (9) The surface excellent in processed part corrosion resistance according to any one of (1) to (8), wherein the glass transition temperature (Tg) of the aqueous resin (a) is 70 ° C. or higher and 200 ° C. or lower. Treated steel sheet.

  (10) The aqueous coating material further contains at least one crosslinking agent (c) selected from the group consisting of an amino resin, a polyisocyanate compound, a block body thereof, an epoxy compound and a carbodiimide compound, as a solid content of the aqueous resin (a). 1 to 40% by mass with respect to 100% by mass, The surface-treated steel sheet excellent in processed part corrosion resistance according to any one of (1) to (9).

(11) The surface-treated steel sheet having excellent processed portion corrosion resistance according to any one of the above (1) to (10), which has a chromate film having a Cr adhesion amount of 5 to 100 mg / m ² as a base treatment layer.

(12) The processed part according to any one of (1) to (10), wherein the processed part has a phosphate conversion chemical film having an adhesion amount of 0.2 to 5.0 g / m ² as a base treatment layer. Surface-treated steel sheet with excellent corrosion resistance.

(13) It has a resin-type film layer formed by applying and drying a base treatment liquid containing the aqueous resin (d) as a base treatment layer, and the coating amount after drying of the film layer is 10 to 3000 mg / surface-treated steel sheet with excellent worked portion corrosion resistance according to any one of (1) to (10), which is a m ^2.

  (14) The aqueous resin (d) is at least one selected from the group consisting of an aqueous epoxy resin, an aqueous phenol resin, an aqueous polyester resin, an aqueous polyurethane resin, an aqueous acrylic resin, and an aqueous polyolefin resin. (13) The surface-treated steel sheet excellent in the processed part corrosion resistance.

  (15) The base treatment liquid according to (13) or (14) further includes 1 to 300% by mass of a silane coupling agent (e) with respect to 100% by mass of the aqueous resin (d). Surface treated steel sheet with excellent corrosion resistance.

  (16) The processed part corrosion resistance according to (15) above, wherein the silane coupling agent (e) contains at least one selected from the group consisting of an epoxy group and an amino group as a reactive functional group. Excellent surface-treated steel sheet.

  (17) The ground treatment liquid according to any one of (13) to (16) further contains 1 to 300% by mass of the polyphenol compound (f) with respect to 100% by mass of the solid content of the aqueous resin (d). A surface-treated steel sheet with excellent processed portion corrosion resistance.

  (18) In the aqueous treatment resin (d), at least one (g) selected from the group consisting of phosphoric acid and hexafluorometal acid is further added to the ground treatment solution according to any one of (13) to (17). A surface-treated steel sheet excellent in processed part corrosion resistance, characterized by containing 0.1 to 100% by mass with respect to 100% by mass of solid content.

  (19) The surface excellent in processed part corrosion resistance according to (18), wherein the hexafluorometal acid contains at least one element selected from the group consisting of Ti, Si, Zr, and Nb Treated steel sheet.

  (20) The phosphate compound (h) is further added to the ground treatment liquid according to any one of (13) to (19) in an amount of 0.1 to 100% with respect to 100% by mass of the solid content of the aqueous resin (d). A surface-treated steel sheet excellent in processed part corrosion resistance, characterized by containing mass%.

  (21) The phosphate compound (h) contains at least one element selected from the group consisting of Mg, Mn, Al, Ca, and Ni as a cation component. Surface treated steel sheet with excellent corrosion resistance.

  (22) Metal oxide particles comprising at least one metal element selected from the group consisting of Si, Ti, Al, and Zr in the ground treatment liquid according to any one of (13) to (21) A surface-treated steel sheet having excellent processed portion corrosion resistance, wherein i) is contained in an amount of 1 to 300% by mass based on 100% by mass of the solid content of the aqueous resin (d).

  (23) The water-based paint applied as an upper layer further contains 1 to 40% by mass of a solid lubricant (j) based on 100% by mass of the solid content of the aqueous resin (a). The surface treatment steel plate excellent in the process part corrosion resistance in any one of thru | or (22).

(24) The surface-treated steel sheet having excellent processed portion corrosion resistance according to (23), wherein the solid lubricant (j) is a polyolefin wax having a particle size of 0.1 to 5.0 μm.

According to the present invention, it is possible to produce a surface-treated steel sheet with excellent corrosion resistance at a processed part in a zinc-based plated steel material in which an MgZn ₂ phase is crystallized during plating, and an industrially excellent effect can be achieved.

The present invention is described in detail below.

  In the present invention, the surface-treated steel sheet is obtained by sequentially providing a zinc-based plating layer, a base treatment layer, and a resin film on the steel sheet. As the base steel sheet of the present invention, both hot-rolled steel sheets and cold-rolled steel sheets can be used, and steel grades are Al killed steel, ultra-low carbon steel sheets to which Ti, Nb, etc. are added, and reinforcing elements such as P, Si, Mn, etc. Various types such as added high strength steel and stainless steel can be applied.

The lower zinc-based plating layer is made of Al: 4 to 10% by mass, Mg: 1 to 5% by mass, and the interval between one plane in the lattice direction constituting the lattice plane of the Bravay lattice is 2.57 mm or more and 3.15 mm or less. Is a plating layer containing a lattice plane having a lattice plane of 3.64 to 4.46 mm, with the balance being Zn and inevitable impurities, the plating layer being [Al / Zn / MgZn ₂ The ternary eutectic structure of [Al phase] and [MgZn ₂ phase] have a mixed metal structure, and the [Al phase] has a lattice direction constituting the lattice plane of the Bravay lattice. An intermetallic compound having a lattice plane in which one plane spacing is 2.57 mm or more and 3.15 mm or less and the other plane spacing is 3.64 mm or more and 4.46 mm or less is obtained . 57 mm or more and 3.15 mm or less, and the other surface interval is 3.6. It is a plating layer containing the lattice plane of 4 to 4.46 mm and the Al phase {110} plane in parallel , or Al: 4 to 22 mass%, Mg: 1 to 5 mass%, Si : 0.5% by mass or less, a lattice plane in which the lattice spacing of one of the lattice directions constituting the lattice plane of the Bravais lattice is 2.57 mm to 3.15 mm and the other surface spacing is 3.64 mm to 4.46 mm containing intermetallic compounds with the balance being a plated layer consisting of Zn and unavoidable impurities, [Mg ₂ Si phase into a green body in the plating layer is [Al / Zn / MgZn ₂ ternary eutectic structure] ] And [Al phase] and [MgZn ₂ phase] are mixed, and the spacing in one of the lattice directions constituting the lattice plane of the Bravay lattice in [Al phase] is 2.57 mm or more. 3.15 mm or less and the distance between the other surfaces is 3.64 mm or more. An intermetallic compound having a lattice plane of 46 mm or less, and a lattice plane in which one surface interval of the intermetallic compound is 2.57 mm or more and 3.15 mm or less, and the other surface distance is 3.64 mm or more and 4.46 mm or less; It is a plating layer containing so that the {110} plane of the Al phase is parallel .
The reason why the Al content in the Zn-Al-Mg based plating layer is limited to 4 to 10% by mass is that when the Al content exceeds 10% by mass, the plating adhesion is lowered, so Si is added. This is because the content of Al in the plating layer that is not necessary needs to be 10% by mass or less. In addition, when the amount is less than 4% by mass, the Al phase does not crystallize as the primary crystal, and thus the effect of improving the corrosion resistance of the processed portion by the Al layer is not observed.

  Therefore, in the plating layer according to the present invention, it is essential to add Si to the plating layer in order to ensure plating adhesion, particularly when the Al concentration is high such that the Al concentration exceeds 10% by mass. .

On the other hand, in the Zn-Al-Mg-Si plating layer, the reason why the Al content is limited to 4 to 22% by mass is that when less than 4% by mass, the Al phase does not crystallize as the primary crystal. This is because the effect of improving the corrosion resistance is not obtained, and when the content exceeds 22% by mass, the effect of improving the corrosion resistance is saturated.

  The reason for limiting the Si content to 0.5% by mass or less (excluding 0% by mass) is that Si has the effect of improving the adhesion, but if it exceeds 0.5% by mass, the adhesion is improved. This is because the effect to be saturated is saturated. Desirably, it is 0.00001-0.5 mass%, More desirably, it is 0.0001-0.5 mass%.

The addition of Si is essential for plating layers with an Al content of more than 10% by mass. However, even in plating layers with an Al content of 10% or less, the effect of improving plating adhesion is great, so the parts are severely processed. It is effective to add Si when high plating adhesion is required. Moreover, [Mg ₂ Si phase] crystallizes in the solidified structure of the plating layer by addition of Si. Since this [Mg ₂ Si phase] is effective in improving corrosion resistance, it is more desirable to increase the amount of Si added and to produce a metal structure in which [Mg ₂ Si phase] is mixed in the solidified structure of the plating layer.
The reason why the Mg content is limited to 1 to 5% by mass is that if the content is less than 1% by mass, the effect of improving the corrosion resistance is insufficient, and if it exceeds 5% by mass, the plating layer becomes brittle and the adhesion is reduced. It is because it falls. Since the above-mentioned [Mg ₂ Si phase] is more easily crystallized as the amount of Mg added is larger, the content of Mg is preferably 2 to 5% by mass for the purpose of further improving the corrosion resistance.

This plating layer is composed of [Zn phase], [Al phase], [MgZn ₂ phase], [Mg ₂ Si phase], intermetallic compound in the [Al / Zn / MgZn ₂ ternary eutectic structure] substrate. A metallographic structure comprising one or more is produced.

Here, [Al / Zn / MgZn ₂ ternary eutectic structure] is an ternary eutectic structure of an Al phase, a Zn phase, and an intermetallic compound MgZn ₂ phase. The formed Al phase corresponds to, for example, an "Al" phase "(Al solid solution that dissolves the Zn phase in a solid solution and contains a small amount of Mg) in an Al-Zn-Mg ternary equilibrium diagram. Is. The Al ″ phase at high temperature usually appears separated into a fine Al phase and a fine Zn phase at room temperature. The Zn phase in the ternary eutectic structure dissolves a small amount of Al, and in some cases Is a Zn solid solution in which a small amount of Mg is dissolved, and the MgZn ₂ phase in the ternary eutectic structure is a metal present in the vicinity of Zn: about 84% by weight in the Zn-Mg binary equilibrium diagram. As far as the phase diagram shows, Si and other additive elements are not dissolved in each phase, or even if they are dissolved, the amount is considered to be very small, but the amount is normal analysis. In this specification, the ternary eutectic structure consisting of these three phases is expressed as [Al / Zn / MgZn ₂ ternary eutectic structure].

  In addition, the [Al phase] is a phase that looks like an island with a clear boundary in the ternary eutectic structure, which is, for example, at a high temperature in an Al—Zn—Mg ternary equilibrium diagram. "Al" phase "(Al solid solution in which Zn phase is dissolved, and contains a small amount of Mg). The Al ″ phase at this high temperature differs in the amount of Zn and Mg dissolved depending on the Al and Mg concentrations in the plating bath. The Al ″ phase at this high temperature is usually fine Al phase and fine Zn at room temperature. Although it is separated into phases, it can be seen that the island-like shape seen at room temperature retains the shape of the Al ″ phase at high temperature. As far as the phase diagram shows, this phase contains Si and other additive elements. Although it is considered that it is not solid solution or is in very small amount even if it is in solid solution, it cannot be clearly distinguished by ordinary analysis. In this specification, the phase holding the structure is referred to as [Al phase], which can be clearly distinguished from the Al phase forming the ternary eutectic structure by microscopic observation.

  In addition, the [Zn phase] is a phase that looks like an island with a clear boundary in the ternary eutectic structure, and actually contains a small amount of Al and a small amount of Mg as a solid solution. There is also. As far as the phase diagram is concerned, it is considered that Si and other additive elements are not dissolved in this phase, or even if they are dissolved. This [Zn phase] can be clearly distinguished from the Zn phase forming the ternary eutectic structure by microscopic observation. The plated layer of the present invention may contain [Zn phase] depending on the production conditions, but since the experiment has hardly seen an effect on the corrosion resistance improvement of the processed part, the plated layer contains [Zn phase]. There is no particular problem.

[MgZn ₂ phase] is a phase that looks like an island with a clear boundary in the ternary eutectic structure, and a small amount of Al may actually be dissolved. As far as the phase diagram is concerned, it is considered that Si and other additive elements are not dissolved in this phase, or even if they are dissolved. This [MgZn ₂ phase] can be clearly distinguished from the MgZn ₂ phase forming the ternary eutectic structure by microscopic observation.

The [Mg ₂ Si phase] is a phase that looks like an island with a clear boundary in the solidified structure of the plating layer to which Si is added. As far as the phase diagram is concerned, it is considered that Zn, Al, and other additive elements are not dissolved, or even if they are dissolved. This [Mg ₂ Si phase] can be clearly distinguished by microscopic observation during plating.

In the surface-treated plated steel sheet of the present invention, a hard and brittle MgZn ₂ phase is crystallized during plating. Therefore, when severe processing is performed, cracks occur in the plating, and corrosion resistance deterioration after processing is likely to occur due to this. .

In order to improve the corrosion resistance of the processed part, in [Al phase], one surface interval in the lattice direction constituting the lattice surface of the Bravay lattice is 2.57 mm or more and 3.15 mm or less, and the other surface interval is 3.64 mm. It is effective to add an intermetallic compound having a lattice plane of 4.46 mm or more.
A plating layer is formed of an intermetallic compound having a lattice plane in which one surface interval in the lattice direction constituting the lattice plane of the Bravais lattice is 2.57 mm to 3.15 mm and the other surface interval is 3.64 mm to 4.46 mm. The reason why the corrosion resistance of the processed part is improved by adding to is considered to be the following two reasons.
1. With the addition of this intermetallic compound, the Al phase crystals become fine and uniform equiaxed crystals, the soft Al phase exists evenly between the ternary eutectic structure and the MgZn ₂ phase, and cracks propagating through the MgZn ₂ phase Since it becomes the end point, the growth of cracks is suppressed.
2. By adding this intermetallic compound, Al phase crystals become fine and uniform equiaxed crystals, and the dendritic arm of the equiaxed Al phase becomes thicker. As a result, the surface area of the dendrites decreases and corrosion progresses. The area of the interface between the Al phase and the ternary eutectic structure that tends to be reduced decreases, and the corrosion rate decreases.

  In addition, an intermetallic compound having a lattice plane in which the lattice spacing of one of the lattice directions constituting the lattice plane of the Bravais lattice is 2.57 mm to 3.15 mm and the other surface spacing is 3.64 mm to 4.46 mm. The reason why the Al phase crystals become fine and uniform equiaxed crystals when added to the plating layer is thought to be that this lattice plane has good consistency with the {110} plane of Al. Since Al has a crystal structure of FCC, the {110} plane is most likely to grow. By adding an intermetallic compound having a lattice plane that has good consistency with the Al {110} plane, it acts as a nucleation site for the Al {110} plane, which is easy to grow. It is thought that many grow in the [110] direction.

  The reason for limiting the distance between one surface in the lattice direction constituting the lattice surface of the Bravais lattice to 2.57 mm or more and 3.15 mm or less is that it matches the Al {110} plane when less than 2.57 mm or more than 3.15 mm. This is because the corrosion resistance of the machined portion is deteriorated and the corrosion resistance of the processed portion is lowered, and the reason why the distance between the other surfaces is limited to 3.64 mm or more and 4.46 mm or less is less than 3.64 mm, or exceeds 4.46 mm. } This is because the compatibility with the surface is deteriorated and the corrosion resistance of the processed portion is lowered.

In addition, since the crystal system of Al is cubic, the crystal system of the intermetallic compound may be any one of cubic, tetragonal, orthorhombic, monoclinic, and hexagonal with a right angle to the axis angle. desirable.
The intermetallic compound is effective when added in a small amount, and when the added amount increases, appearance defects such as a rough appearance after plating occur. Therefore, the upper limit is desirably 1% by mass.

  As a result of the inventors investigating a large number of Al phases in plating, intermetallic compounds having a size of several μm were observed from the center of most Al phase dendrites. Further, when the crystal orientations of the intermetallic compound and the Al phase were identified using the EBSP method, one interplanar spacing in the lattice direction of the intermetallic compound was 2.57 mm or more and 3.15 mm or less, and the other interplanar spacing was 3.64 mm or more. It was confirmed that the lattice plane of 4.46 mm or less and the Al phase {110} plane were parallel, and the Al phase dendrite grew in the [110] direction.

As an example of an intermetallic compound present in the Al phase, TiAl ₃ present in the Al phase in the Al—Zn—Mg—Si based plating is shown in FIG. Although this TiAl ₃ is actually considered to be a solid solution of Si or a part of Al in the compound is considered to be replaced by Si, the crystal structure obtained by electron beam diffraction, Kikuchi pattern, etc. is the same as TiAl ₃ Therefore, it is expressed as TiAl ₃ here. The upper diagram in FIG. 1 is a photomicrograph (magnification 3000 times) of the plated layer of the plated steel material in the present invention, and the lower diagram shows the distribution state of each structure in the photograph. As can be seen from this figure, the Al phase can be clearly identified by the micrograph of the plated layer of the plated steel material in the present invention.

Moreover, the pole figure of FIG. 2 shows the electron beam diffraction result of the intermetallic compound of FIG. 1 and an Al phase. From the pole figure, it can be seen that the Al phase dendrite shown in FIG. 1 has a {110} plane growing in the [110] direction. Further, since the positions of the pole figures in FIG. 2 are in good agreement, it can be understood that the {110} plane of the Al phase has the same orientation as the {110} plane and {102} plane of TiAl ₃ .
As a result of determining the crystal orientation of the Al phase and TiAl ₃ by the EBSP method, it becomes clear that the {110} plane of the Al phase in FIG. 1 is parallel to all the {110} plane and {102} plane of TiAl _3. It was. This is considered to be the result of the growth of Al phase dendrite using the {110} plane and the {102} plane of TiAl ₃ as nucleation sites for the Al phase.

  By using the EBSP method in this way, it is possible to analyze the consistency between a specific lattice plane of the intermetallic compound and the lattice plane of the Al phase.

  In the present invention, the size of the intermetallic compound is not particularly limited, but what the inventors have observed is a size of 10 μm or less. Moreover, although the abundance ratio of the intermetallic compound in the Al phase is not particularly limited, it is desirable that it exists in the Al phase exceeding the majority.

There are no particular limitations on the method of adding the intermetallic compound, and a method of making the intermetallic compound fine powder turbid in the bath, a method of dissolving the intermetallic compound in the bath, or the like can be applied.
The method for producing a plating layer in the present invention is not particularly limited, and a normal non-oxidizing furnace hot-dip plating method can be applied. Even when Ni pre-plating is applied as the lower layer, a conventional pre-plating method may be applied.

There are no particular restrictions on the amount of plating deposited, but it is preferably 10 g / m ² or more from the viewpoint of corrosion resistance and 350 g / m ² or less from the viewpoint of workability.
As the base treatment layer, a chromate film, a phosphate film, or a resin-based film formed by applying a treatment liquid containing an aqueous resin to the plating surface and then drying it is used. The ground treatment layer is located between the plating surface and the film and contributes to improvement in adhesion and corrosion resistance during processing.

It does not specifically limit as a chromate film | membrane used for a surface treatment, The chromate film | membrane formed from a well-known processing agent and a processing method can be used. For example, a post-water-washing electrolytic reduction chromate film, a reactive chromate film mainly composed of trivalent chromium hydrated oxide, a chromate liquid mainly composed of trivalent chromium and hexavalent chromium hydrated oxide is applied and dried. An anhydrous chromate coating chromate film can be used. Further, the chromate film may be a composite chromate film containing phosphoric acid, etching fluoride, fine silica and the like. The amount of adhesion is 5 to 100 mg / m ² in terms of Cr. Less than 5 mg / m ² is not preferable because corrosion resistance cannot be obtained. If it exceeds 100 mg / m ² , the chromate film itself is prone to cohesive failure and adhesion cannot be obtained. It is desirable that the chromate film has a high trivalent chromium / 6 hexavalent chromium ratio and is difficult to dissolve in water-based paint.

The phosphate film used for the base treatment is composed of phosphates such as zinc, iron, nickel, manganese, calcium, and magnesium. It does not specifically limit as a processing agent and a processing method, A well-known processing agent and a processing method can be used. For example, any processing such as reactive processing, coating processing, and electrolytic processing may be used as the processing method. Although it does not specifically limit as a process process, after giving the zinc plating of this invention etc. to a steel plate, it processes through each process of phosphate pre-processing (surface adjustment), phosphate processing, water washing, and drying. Is common. There is no particular limitation on the above-mentioned phosphate pretreatment (surface conditioning) method. For example, an aqueous zinc phosphate solution or a colloidal Ti solution is generally used, and acts as a precipitation site for phosphate crystals. It is carried out to form a dense film. The adhesion amount is preferably in the range of 0.2 to 5 g / m ² for the reasons of corrosion resistance and adhesion. If it is less than 0.2 g / m ² , corrosion resistance cannot be obtained. If it exceeds 5 g / m ² , adhesion cannot be obtained by severe processing due to cohesive failure of the phosphate film.

  As the water-based resin (d) of the resin-based film used for the base treatment, in addition to a water-soluble resin, a resin (water dispersibility) that is inherently insoluble in water but can be finely dispersed in water like an emulsion or a suspension. Including resin). The type of the aqueous resin (d) is not particularly limited, and examples thereof include an aqueous epoxy resin, an aqueous phenol resin, an aqueous polyester resin, an aqueous polyurethane resin, an aqueous acrylic resin, and an aqueous polyolefin resin.

  The aqueous epoxy resin is not particularly limited. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, resorcin type epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, resorcin type epoxy resin. In the presence of an epoxy resin such as a novolac-type epoxy resin, which is obtained by reacting with an amine compound such as diethanolamine or N-methylethanolamine and neutralizing with an organic acid or an inorganic acid, or in the presence of the epoxy resin, a high acid value Examples thereof include those obtained by radical polymerization of an acrylic resin, neutralized with ammonia or an amine compound, and dispersed in water.

  The aqueous phenol resin is not particularly limited. For example, a methylolated phenol resin obtained by addition reaction of aromatics such as phenol, resorcin, cresol, bisphenol A, paraxylylene dimethyl ether and formaldehyde in the presence of a reaction catalyst. And the like obtained by reacting the phenol resin with amine compounds such as diethanolamine and N-methylethanolamine and neutralizing with an organic acid or inorganic acid.

  The aqueous polyester resin is not particularly limited. For example, ethylene glycol, propylene glycol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, triethylene glycol, bisphenol hydroxypropyl ether, glycerin, trimethylol ethane, trimethylol propane. Dehydration condensation of polyhydric alcohols such as phthalic anhydride, isophthalic acid, terephthalic acid, succinic anhydride, adipic acid, sebacic acid, maleic anhydride, itaconic acid, fumaric acid, and hymic anhydride And those obtained by neutralizing with ammonia or amine compound and dispersing in water.

  The aqueous urethane resin is not particularly limited. For example, ethylene glycol, propylene glycol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, triethylene glycol, bisphenol hydroxypropyl ether, glycerin, trimethylol ethane, trimethylol propane. And polyhydric alcohols such as hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate and the like, and chain extension with diamine or the like, followed by water dispersion.

  The aqueous acrylic resin is not particularly limited, and examples thereof include unsaturated monomers such as styrene, alkyl (meth) acrylates, (meth) acrylic acid, hydroxyalkyl (meth) acrylates, and alkoxysilane (meth) acrylates. Can be obtained by radical polymerization in an aqueous solution using a polymerization initiator. The polymerization initiator is not particularly limited, and for example, persulfates such as potassium persulfate and ammonium persulfate, and azo compounds such as azobiscyanovaleric acid and azobisisobutyronitrile can be used.

  The aqueous olefin resin is not particularly limited. For example, after radical polymerization of ethylene and an unsaturated carboxylic acid such as methacrylic acid, acrylic acid, maleic acid, fumaric acid, itaconic acid, and crotonic acid under high temperature and pressure, ammonia is used. And a compound obtained by neutralizing with an amine compound, a metal compound such as KOH, NaOH, LiOH or the like, ammonia or an amine compound containing the above metal compound, and dispersing in water.

  The aqueous resin (d) may be used alone or in combination of two or more. One or more aqueous composite resins obtained by modifying at least one other aqueous resin in the presence of at least one aqueous resin may be used. Furthermore, if necessary, a crosslinking agent may be added to the aqueous resin, or a crosslinking agent may be introduced into the resin skeleton. The crosslinking agent is not particularly limited, and examples thereof include melamine, epoxy, carbodiimide, blocked isocyanate, oxazoline and the like.

  The resin-based film used for the base treatment preferably further contains a silane coupling agent (e). Silane coupling agents are known to chemically bond to both metals and organics. By blending such a silane coupling agent, the adhesion with the plating of the resin film is dramatically improved, and as a result, the corrosion resistance of the processed part is improved.

  The silane coupling agent is not particularly limited. For example, vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ sold by Shin-Etsu Chemical, Nippon Unicar, Chisso, Toshiba Silicone, etc. -Aminopropylethoxysilane, N- [2- (vinylbenzylamino) ethyl] -3-aminopropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyl Methyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, 2- (3 4- Poxycyclohexyl) ethyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ -Aminopropylmethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane and the like can be mentioned. From the viewpoint of adhesion to the resin film, it is more preferable to use a silane coupling agent containing an epoxy group and / or an amino group as the reactive functional group. The said silane coupling agent may be used independently and may use 2 or more types together. In consideration of the stability of the treatment liquid, an organic acid such as acetic acid can be added.

  The silane coupling agent is desirably contained in an amount of 1 to 300% by mass with respect to 100% by mass of the aqueous resin. If the amount is less than 1% by mass, the amount of the silane coupling agent is insufficient, so that sufficient adhesion cannot be obtained during processing, resulting in poor corrosion resistance. If it exceeds 300% by mass, the effect of improving the adhesion may be saturated and uneconomical, or the stability of the treatment liquid may be reduced.

The resin-based film used for the base treatment preferably further contains a polyphenol compound (f). Polyphenol compounds produce chelating action on metals and hydrogen bonding with hydrophilic groups of aqueous resins. By blending such a polyphenol compound, the adhesion between the plating and the resin-based film, and the resin-based film and the upper layer film is dramatically improved, and as a result, the corrosion resistance of the processed part is improved.
The polyphenol compound is a compound having two or more phenolic hydroxyl groups bonded to a benzene ring or a condensate thereof. Examples of the compound having two or more phenolic hydroxyl groups bonded to the benzene ring include gallic acid, pyrogallol, catechol and the like. The condensate of the compound having two or more phenolic hydroxyl groups bonded to the benzene ring is not particularly limited, and examples thereof include polyphenol compounds that are widely distributed in the plant kingdom, usually called tannic acid. Tannic acid is a general term for aromatic compounds having a complex structure having a large number of phenolic hydroxyl groups widely distributed in the plant kingdom. The tannic acid may be hydrolyzable tannic acid or condensed tannic acid. The tannic acid is not particularly limited, and examples thereof include hameli tannin, oyster tannin, chatannin, pentaploid tannin, gallic tannin, milobalan tannin, dibidi tannin, argarovira tannin, valonia tannin, catechin tannin and the like. . Examples of the tannic acid include commercially available ones such as “tannic acid extract A”, “B tannic acid”, “N tannic acid”, “industrial tannic acid”, “purified tannic acid”, “Hi tannic acid”, "F tannic acid", "local tannic acid" (all manufactured by Dainippon Pharmaceutical Co., Ltd.), "tannic acid: AL" (manufactured by Fuji Chemical Industry Co., Ltd.) and the like can also be used. The said polyphenol compound may be used by 1 type, and may use 2 or more types together.
The polyphenol compound is desirably contained in an amount of 1 to 300% by mass with respect to 100% by mass of the aqueous resin. If the amount is less than 1% by mass, the amount of the polyphenol compound is insufficient, so that sufficient adhesion cannot be obtained during processing, resulting in poor corrosion resistance. On the other hand, if it exceeds 300% by mass, the adhesion and corrosion resistance may be lowered, and the stability of the treatment liquid may be lowered.

  It is desirable that the resin-based film used for the base treatment further contains at least one (g) selected from the group consisting of phosphoric acid and hexafluorometal acid. The phosphoric acid and hexafluorometal acid may be used alone or in combination. These acids activate the plating surface by etching and promote the action of silane coupling agents and polyphenol compounds on plating.

  The phosphoric acid is not particularly limited, and examples thereof include orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid, and polyphosphoric acid. In addition to the above action, phosphoric acid has the effect of forming a phosphate layer on the plating surface to passivate it, thereby improving the corrosion resistance. The said phosphoric acid may be used by 1 type, and may use 2 or more types together.

The hexafluorometal acid is not particularly limited, and examples thereof include hexafluorophosphoric acid, hexafluorotitanic acid, hexafluorozirconic acid, hexafluorosilicic acid, hexafluoroniobic acid, hexafluoroantimonic acid, and ammonium salts and potassium salts thereof. Sodium salt, calcium salt, magnesium salt and the like. In addition to the above action, hexafluorometal acid improves the corrosion resistance because a stable metal oxide film layer is formed on the plating surface by the metal supplied from hexafluorometal acid. In particular, a metal containing Ti, Zr, Si, or Nb is preferable. The said hexafluoro metal acid may be used by 1 type, and may use 2 or more types together.
It is desirable that at least one (g) selected from the group consisting of phosphoric acid and hexafluorometal acid is contained in an amount of 0.1 to 100% by mass with respect to 100% by mass of the solid content of the aqueous resin (d). If the amount is less than 0.1% by mass, the amount of these acids is insufficient, and the corrosion resistance may be lowered. When it exceeds 100% by mass, the resin-based film becomes brittle, and the adhesiveness may be lowered due to film cohesive failure.

  It is desirable that the resin-based film used for the base treatment further contains a phosphate compound (h). By blending this phosphate compound, a hardly soluble phosphate film is formed on the plating surface during the formation of the resin film. That is, as the plating is dissolved by the phosphate ions of the phosphate, the pH rises on the plating surface, and as a result, a phosphate precipitation film is formed and the corrosion resistance is improved.

The phosphate compound is not particularly limited, and examples thereof include metal salts such as orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, and polyphosphoric acid, and organic metal salts such as phytic acid and phosphonic acid. The cation species is not particularly limited, and examples thereof include Cu, Co, Fe, Mn, Sn, V, Mg, Ba, Al, Ca, Sr, Nb, Y, Ni, and Zn. As the cation species, it is more preferable to use Mn, Mg, Al, Ca, Ni. The said phosphate compound may be used by 1 type, and may use 2 or more types together.
It is preferable to contain 0.1-100 mass% of phosphate compounds with respect to 100 mass% of solid content of aqueous resin (d). If it is less than 0.1% by mass, the amount of the phosphate compound is insufficient, so that the corrosion resistance may be lowered. When it exceeds 100% by mass, the resin-based film becomes brittle, and the adhesiveness may be lowered due to film cohesive failure.

  The resin-based film used for the base treatment preferably further contains metal oxide particles (i) made of at least one metal element selected from the group consisting of Si, Ti, Al, and Zr. By adding these metal oxide particles, the corrosion resistance can be further increased.

  The metal oxide particles are not particularly limited, and examples thereof include silica particles, alumina particles, titania particles, and zirconia particles. As said metal oxide particle, a thing with an average particle diameter of about 1-300 nm is suitable. These may be used alone or in combination of two or more.

  The metal oxide particles are preferably contained in an amount of 1 to 300% by mass with respect to 100% by mass of the solid content of the aqueous resin (d). If the amount is less than 1% by mass, the amount of the metal oxide particles is insufficient, so that the effect of improving the corrosion resistance may not be obtained. If it exceeds 300% by mass, the resin-based film becomes brittle, and the adhesion may be lowered due to the film cohesive failure.

Moreover, you may add an organic solvent, surfactant, an antifoamer, etc. to the process liquid containing the aqueous resin used for forming a resin-type membrane | film | coat as needed. The adhesion amount after drying of the ground treatment layer is preferably 10 to 3000 mg / m ² . If it is less than 10 mg / m < ² >, adhesiveness is inferior and the corrosion resistance of a processed part is inadequate. On the other hand, when it exceeds 3000 mg / m ² , not only is it uneconomical, but also the workability is lowered and the corrosion resistance is deteriorated.

  The method for applying the ground treatment layer is not particularly limited, and generally known coating methods such as roll coating, air spray, airless spray, and immersion can be applied. Drying and baking after coating may be performed by a known method such as a hot air furnace, an induction heating furnace, a near infrared furnace, or a combination of these in consideration of the polymerization reaction and curing reaction of the resin.

  Next, the resin film formed as the upper layer will be described below. As a result of intensive research, the present inventors applied and dried an aqueous paint containing 5 to 50% by mass of silica particles (b) with respect to 100% by mass of the solid content of the aqueous resin (a). It has been found that the corrosion resistance of the processed part can be improved by using the obtained resinous film.

The water-based resin (a) of the water-based paint includes a water-soluble resin and a resin (water-dispersible resin) that is inherently insoluble in water but can be finely dispersed in water, such as an emulsion or suspension. . The type of the aqueous resin (a) is not particularly limited, and examples thereof include an aqueous epoxy resin, an aqueous phenol resin, an aqueous polyester resin, an aqueous polyurethane resin, an aqueous acrylic resin, and an aqueous polyolefin resin. The aqueous resin (a) may be used alone or in combination of two or more. One or more aqueous composite resins obtained by modifying other aqueous resins in the presence of at least one aqueous resin may be used. Among the aqueous resins (a), in particular, when emphasizing the balance of adhesion, elongation, shear strength, corrosion resistance, wear resistance, and chemical resistance, a polyurethane resin having a polyester skeleton portion and a polyether skeleton portion is used. It is preferable to select.
Generally, the physical properties of the polyurethane resin are controlled by the balance between the hard segment and the soft segment and the crosslink density, so that a wide range of properties can be controlled by the type of the skeleton and isocyanate. The elongation and tensile strength adjustment of the polyurethane resin used in the present invention are controlled by the content of the polyester skeleton showing flexibility and the polyether skeleton showing the toughness and the content of the urethane bond, and if the latter content increases, A tough characteristic with low elongation but high tensile strength can be obtained.
The polyester skeleton can be obtained from a polyester polyol compound, and the polyether skeleton can be obtained from a polyether polyol compound.

  Examples of the polyester polyol compound include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, neopentyl glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1 , 4-butylene glycol, 3-methylpentanediol, hexamethylene glycol, hydrogenated bisphenol A, trimethylolpropane, and glycerin and other low molecular weight polyols such as succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, Obtained by reaction with polybasic acids such as isophthalic acid, terephthalic acid, trimellitic acid, tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, and hexahydrophthalic acid, Selected from those having a hydroxyl group at the end.

Examples of the polyether polyol compound include bisphenol skeleton-containing glycols such as methylene bisphenol, ethylidene bisphenol, butylidene bisphenol, and isopropylidene bisphenol, and alkylene oxides having 2 to 4 carbon atoms (for example, ethylene oxide, propylene oxide, butylene). Oxides) are preferred, and those having 1 to 10 moles of alkylene oxide added are preferred.
The mass ratio of the polyether skeleton and the polyester skeleton is more preferably in the range of 10:90 to 70:30. When the ratio of the polyether is larger than the above range, it is tough but has a low elongation, so it is inferior in a high degree of moldability.

  Examples of the isocyanate group that bonds the ester skeleton and the ether skeleton of the polyurethane resin include monomers, dimers, trimers of aromatic diisocyanates such as tolylene diisocyanate, diphenyl meta diisocyanate, and xylylene diisocyanate, and polyethers thereof. Reactants with polyols and polyester polyols, and their hydrogenated derivatives, alicyclic isocyanates such as alicyclic isocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and aliphatic isocyanate monomers, dimers, 3 A reaction product of a monomer and a polyether polyol or polyester polyol, or a mixture thereof can also be used. The blending amount depends on the polyester polyol and polyether polyol to be used, but 5 to 20% by mass of the polyurethane resin in terms of NCO can provide optimum processing characteristics as the resin physical properties.

  The aqueous epoxy resin is not particularly limited. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, resorcin type epoxy resin, hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, resorcin type epoxy resin. In the presence of an epoxy resin such as a novolac-type epoxy resin, which is obtained by reacting with an amine compound such as diethanolamine or N-methylethanolamine and neutralizing with an organic acid or an inorganic acid, or in the presence of the epoxy resin, a high acid value Examples thereof include those obtained by radical polymerization of an acrylic resin, neutralized with ammonia or an amine compound, and dispersed in water.

  The aqueous phenol resin is not particularly limited. For example, a methylolated phenol resin obtained by addition reaction of aromatics such as phenol, resorcin, cresol, bisphenol A, paraxylylene dimethyl ether and formaldehyde in the presence of a reaction catalyst. And the like obtained by reacting the phenol resin with amine compounds such as diethanolamine and N-methylethanolamine and neutralizing with an organic acid or inorganic acid.

  The aqueous polyester resin is not particularly limited. For example, ethylene glycol, propylene glycol, diethylene glycol, 1,6-hexanediol, neopentyl glycol, triethylene glycol, bisphenol hydroxypropyl ether, glycerin, trimethylol ethane, trimethylol propane. Dehydration condensation of polyhydric alcohols such as phthalic anhydride, isophthalic acid, terephthalic acid, succinic anhydride, adipic acid, sebacic acid, maleic anhydride, itaconic acid, fumaric acid, and hymic anhydride And those obtained by neutralizing with ammonia or amine compound and dispersing in water.

  The aqueous acrylic resin is not particularly limited, and examples thereof include unsaturated monomers such as styrene, alkyl (meth) acrylates, (meth) acrylic acid, hydroxyalkyl (meth) acrylates, and alkoxysilane (meth) acrylates. Can be obtained by radical polymerization in an aqueous solution using a polymerization initiator. The polymerization initiator is not particularly limited, and for example, persulfates such as potassium persulfate and ammonium persulfate, and azo compounds such as azobiscyanovaleric acid and azobisisobutyronitrile can be used.

  The aqueous olefin resin is not particularly limited. For example, after radical polymerization of ethylene and an unsaturated carboxylic acid such as methacrylic acid, acrylic acid, maleic acid, fumaric acid, itaconic acid, and crotonic acid under high temperature and pressure, ammonia is used. And a compound obtained by neutralizing with an amine compound, a metal compound such as KOH, NaOH, LiOH or the like, ammonia or an amine compound containing the above metal compound, and dispersing in water.

  The glass transition temperature (Tg) of the aqueous resin (a) is more preferably 70 ° C. or higher and 200 ° C. or lower. When the temperature is lower than 70 ° C, sufficient processing characteristics may not be obtained when the temperature rises due to deformation heat of the material or frictional heat between the material and the mold during processing, and the temperature exceeds 200 ° C. In some cases, the film formability of the film is lowered, and corrosion resistance cannot be obtained.

Fine silica (b) is added to improve corrosion resistance and toughen the film. The fine silica (b) is not particularly limited and is preferably a silica fine particle such as colloidal silica or fumed silica having a primary particle diameter of 3 to 50 nm because the film is a thin film. Commercially available products include, for example, Snowtex O, Snowtex N, Snowtex C, Snowtex IPA-ST (Nissan Chemical Industry), Adelite AT-20N, AT-20A (Asahi Denka Kogyo), Aerosil 200 (Nippon Aerosil) Etc.
The amount of fine silica (b) is 5 to 50% by mass based on 100% by mass of the aqueous resin (a). If it is less than 5%, the effect of improving the corrosion resistance and workability is small, and if it exceeds 50%, the binder effect of the resin is reduced, the corrosion resistance is lowered and the elongation and strength of the resin are lowered, and the workability is lowered.

It is preferable that the water-based paint further contains at least one (c) crosslinking agent selected from the group consisting of amino resins, polyisocyanate compounds, block bodies thereof, epoxy compounds, and carbodiimide compounds. By blending these cross-linking agents, the cross-linking density of the film can be increased, and the corrosion resistance and workability are improved. These crosslinking agents may be used alone or in combination of two or more.
It does not specifically limit as said amino resin, For example, a melamine resin, a benzoguanamine resin, a urea resin, a glycoluril resin etc. can be mentioned.
It does not specifically limit as said polyisocyanate compound, For example, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, tolylene diisocyanate etc. can be mentioned. The blocked product is a blocked product of the polyisocyanate compound.
The epoxy compound is not particularly limited as long as it has a plurality of oxirane rings. For example, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, sorbitan polyglycidyl ether, pentaerythritol polyglycidyl ether Glycerin polyglycidyl ether, trimethylpropane polyglycidyl ether, neopentyl glycol polyglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol glycol diglycidyl ether, polypropylene glycol glycol diglycidyl ether, 2,2-bis -(4'-glycidyloxyphenyl) propane, tris (2,3-epoxypropyl) isocyanurate And bisphenol A diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, and the like.
As the carbodiimide compound, for example, after synthesizing an isocyanate-terminated polycarbodiimide by a condensation reaction involving decarbonization of a diisocyanate compound such as aromatic diisocyanate, aliphatic diisocyanate, and alicyclic diisocyanate, the reactivity with an isocyanate group is further increased. Examples thereof include compounds to which a hydrophilic segment having a functional group is added.

As for the quantity of these hardening | curing agents, 1-40 mass% is preferable with respect to 100 mass% of solid content of aqueous resin (a). If the amount is less than 1%, the amount may not be sufficient and the effect of addition may not be obtained. If the amount exceeds 40%, the film becomes brittle due to excessive curing, and the workability and corrosion resistance deteriorate.
The water-based paint of the present invention preferably further contains a solid lubricant (j) for improving slidability.

  By containing the above-mentioned solid lubricant (j), the lubricity of the resin-based film is improved, workability at the time of press molding is improved, wrinkles are prevented by molds and handling, etc., and abrasion scratches are prevented during transport of molded products and coils. Is effective against.

  The solid lubricant (j) is not particularly limited, and examples thereof include known fluorine-based, hydrocarbon-based, fatty acid amide-based, ester-based, alcohol-based, metal soap-based and inorganic lubricants. As a selection criterion for lubricating additives for improving processability, it is necessary to select a material that exists on the surface of the resin film rather than being dispersed in the resin film on which the added lubricant is formed. This is necessary in order to reduce the friction between the surface of the object and the mold and maximize the lubrication effect. That is, when the lubricant is dispersed in the formed resin film, the surface friction coefficient is high, the resin film is easily broken, and powdery substances are peeled and deposited, resulting in poor appearance and reduced workability called powdering phenomenon. Arise. As the substance that exists on the surface of the resin film, a substance that is incompatible with the resin and has a small surface energy is selected.

Among them, the use of polyolefin wax is more preferable because the dynamic friction coefficient of the surface is lowered, the workability is greatly improved, and the corrosion resistance after processing is also improved. Examples of the wax include hydrocarbon waxes such as paraffin, microcrystalline, and polyethylene. At the time of processing, since the film temperature rises due to the deformation heat and frictional heat of the material, the melting point of the wax is more preferably 70 to 160 ° C. If it is less than 70 degreeC, it may soften and melt at the time of a process, and the outstanding characteristic as a solid lubricant may not be exhibited. In addition, when the melting point exceeds 160 ° C., hard particles are present on the surface and the friction characteristics are deteriorated, so that high moldability may not be obtained.
The particle diameter of these waxes is more preferably 0.1 to 5 μm. If it exceeds 5 μm, the distribution of the solidified wax may be non-uniform, or the resin-based film may fall off. Moreover, when it is less than 0.1 μm, the workability may be insufficient.

The solid lubricant (j) is preferably contained in an amount of 1 to 40% by mass with respect to 100% by mass of the solid content of the aqueous resin (a). If it is less than 1%, the workability improvement effect is small, and if it exceeds 40%, the workability and the corrosion resistance may be lowered.
The water-based paint of the present invention may contain a conductive material for improving weldability and a colored pigment material for improving design. Moreover, even if various additives, such as a sedimentation inhibitor, a leveling agent, and a thickener, are added, the effect of this invention is not impaired.

  Since the present invention is a water-based paint, the surface tension is high and the surface wettability is inferior to that of a solvent system, and a uniform coating property may not be obtained when a predetermined amount is applied to the surface to be coated. However, in order to ensure performance such as high workability and corrosion resistance, it is indispensable that uniform coating is performed on the surface to be coated. For this reason, it is known to add a wetting agent or thickener. Examples of the wetting agent include known surfactants for reducing the surface tension, such as fluorine-based and silicon-based reducing surface tension. In particular, among these compounds, it is preferable to contain 0.05 to 0.5% of an acetylene glycol / alcohol surfactant having 0 to 20 moles of added ethylene oxide with respect to the aqueous coating composition. The acetylene glycol / alcohol surfactant is characterized by a high wetting rate and a defoaming effect at the same time. On the other hand, fluorine-based and silicon-based surfactants are not suitable because they are excellent in surface tension reducing ability, but have a low wetting rate and inferior defoaming property and inferior adhesion to top coat.

  In addition, as a countermeasure for thickeners, when sufficient surface coverage cannot be ensured with only a wetting agent on the surface of the surface to be coated, or when the coating thickness is not ensured by a coating method typified by a roll coater. May be added. Since the coating material of the present invention is usually applied to an object to be coated at a high speed, a thixo type thickener typified by a cellulose type has little effect under coating conditions that receive high-speed shear stress. Under such coating conditions, it is known that a Newtonian type thickener is suitable. As the thickener used in the present invention, a thickener having an ether / urethane skeleton having a molecular weight of 1000 to 20000 is particularly preferred.

  Normally, when additives are added to paints, the original performance is often lowered, but this thickener has a very low impact when it remains in the coating because it is a skeleton that is difficult to hydrolyze. It is a feature. The addition amount is 0.01 to 0.2% with respect to the resin solid content of the water-based coating composition, and is usually determined by the coating conditions. If the amount is less than 0.01%, the thickening effect is small. If the amount exceeds 0.2%, the viscosity becomes too large, which may cause problems in coating properties and deteriorate high workability and excellent corrosion resistance. .

The coating composition of the present invention composed of the compounds described above varies depending on the application and coating conditions, but generally it is desirable to adjust the non-volatile content concentration to 15 to 30%, the viscosity to 10 to 50 cps, and the surface tension to 80 dyne / cm or less. . The reason is that it is easy to control the target film thickness, and to obtain a uniform film thickness with no unevenness in appearance and no repelling of the paint. The existing coating methods such as roll coating method, dipping method, air knife drawing, groove roll method, and curtain coating method can be adopted as the coating method, but the reverse roll is easy to obtain film thickness control, film thickness accuracy, and non-uniform appearance. Coat application is most desirable. The coating amount was 0.2 to 5 g / m ² as a dry film thickness. Immediately after coating, the plate temperature was baked to 80 to 200 ° C., preferably 120 to 160 ° C. by hot air, far-infrared furnace, electric furnace, combustion furnace, induction heating. After that, the film is forcedly cooled by a method such as water cooling and dried to form a film.

The reason for limiting the range of coating weight 0.2-5 g / m ² is insufficient processing unit corrosion resistance present invention is intended is less than 0.2 g / m ^2. If it exceeds 5 g / m ² , welding cannot be performed, and problems such as blocking tend to occur. The reason for limiting the baking plate temperature is that if it is less than 80 ° C., the reflow and crosslinking reaction of the resin is insufficient, resulting in a film having many defects on the rough surface, and if it exceeds 200 ° C., the resin undergoes thermal decomposition and heat oxidation, and the performance deteriorates. The most desirable uniform and smooth defect-free film by melting and crosslinking of the resin is obtained in the range of 120 to 160 ° C.

  Hereinafter, the present invention will be described specifically by way of examples.

First, a cold rolled steel sheet having a thickness of 0.8 mm was prepared, and this was added to a 450 ° C. Zn—Mg—Al plating bath and Zn—Mg—Al—Si plating bath added with various metals or intermetallic compounds for 3 seconds. Hot dip plating was performed, and the amount of plating adhered was adjusted to 80 g / m ² on one side by N ₂ wiping. Table 1 shows the plating composition of the obtained plated steel sheet and the intermetallic compounds present in the Al phase. The intermetallic compounds were analyzed for elements and composition using EDX. Table 1 shows the surface index of the surface close to the Al {110} surface of each intermetallic compound, the direction index in the lattice direction constituting the surface, and the surface spacing.
Although some Al-based intermetallic compounds were dissolved in the plating bath and recrystallized, some of the Al was considered to be replaced by Si, but there were significant changes in crystal orientation and interplanar spacing. In the examples, it was expressed as an Al-based intermetallic compound not substituted with Si.
The crystal orientation of the Al phase and the intermetallic compound was determined from the polished plated surface using the EBSP method, and the consistency between the {110} plane of the Al phase and each lattice plane of the intermetallic compound was investigated. The results are shown in Table 1. A case where the {110} plane of the Al phase and each lattice plane of the intermetallic compound were parallel, and a case where no relationship was found between the {110} plane of the Al phase and each lattice plane of the intermetallic compound. It was.
Next, after degreasing the plated steel sheet, a coating-type chromate treatment with a Cr adhesion amount of 50 mg / m ² was performed, and on that, 100% by mass of the polyurethane resin produced according to Production Example 1 was added to fine silica (Snowtex-N : Manufactured by Nissan Chemical Industries Co., Ltd.) was coated with an aqueous paint containing 30%, and baked so that the ultimate plate temperature was 150 ° C., to prepare a surface-treated steel sheet having a coating with an adhesion amount of 1.0 g / m ² .
Polyurethane resin production example 1
80 parts of a polyester polyol having an average molecular weight of 900 synthesized from adipic acid having a hydroxyl group at the terminal and 1,4-butylene glycol, 120 parts of a 3 mol adduct of bisphenol A propylene oxide having an average molecular weight of 700, and 2,2-bis ( 12 parts of hydroxymethyl) propionic acid are added to 100 parts of N-methyl-2-pyrrolidone and heated to 80 ° C. to dissolve. Thereafter, 100 parts of hexamethylene diisocyanate is added, heated to 110 ° C. and reacted for 2 hours, and neutralized by adding 11 parts of triethylamine. This solution was dropped into an aqueous solution obtained by mixing 5 parts of ethylenediamine and 570 parts of deionized water under strong stirring to obtain an aqueous urethane resin. The Tg of this resin is 85 ° C., and the weight ratio of the polyester skeleton to the polyether skeleton is polyester skeleton: polyether skeleton = 40: 60.
The corrosion resistance of the processed part was evaluated by the corrosion resistance of the sample after the overhang test. In the overhang test, a 200 × 200 mm blank plate with a 120 mmφ spherical head was used to overhang a height of 35 mm. As a result of measuring the amount of distortion of the sample using a scribed circle, it was found that the height was 33% and the circumference was 9%.
Corrosion resistance was determined by scoring as shown below for the occurrence of white rust after SST120hr for the processed parts after overhanging. A score of 3 or more was accepted.
10: No white rust occurrence 9: White rust occurrence less than 1% 8: White rust occurrence 1% or more and less than 3% 7: White rust occurrence 3% or more and less than 5% 6: White rust occurrence 5% or more and less than 7% 5: White Rust generation 7% to less than 10% 4: White rust generation 10% to less than 15% 3: White rust generation 15% to less than 20% 2: White rust generation 20% to less than 30% 1: White rust generation 30% or more Evaluation The results are shown in Table 1.
In Nos. 5 and 11, since the interplanar spacing between the lattice planes constituting the surface close to the Al {110} plane of the intermetallic compound is outside the range of the present invention, the corrosion resistance of the processed part was rejected. Reference numerals 20, 26, 32, 38, 44, 50, and 56 are plated steel sheets to which no intermetallic compound is added for comparison of corrosion resistance. The products of the present invention other than these were surface-treated plated steel sheets with excellent processed portion corrosion resistance.

First, a cold-rolled steel sheet having a thickness of 0.8 mm was prepared, and hot-dip plating was performed for 3 seconds in a 450 ° C. Zn—Mg—Al plating bath and Zn—Mg—Al—Si plating bath to which Ti was added. _The amount of plating adhesion was adjusted to 80 g / m ² on one side by ₂ wiping. Table 2 shows the plating composition of the obtained plated steel sheet and the intermetallic compounds present in the Al phase. The intermetallic compound present in the Al phase was TiAl ₃ and Ti (Al _1-X Si _x ) ₃ which was considered to be a part of Al of TiAl ₃ being replaced by Si. In either case, the lattice direction constituting the {110} plane, the plane spacing in the [110] direction and the [002] direction are 2.725Å, 4.29Å, the lattice direction constituting the {102} plane, and the [102] direction, respectively. The surface spacing in the [100] direction was 2.8682 mm and 3.8537 mm, respectively.

The crystal orientation of the Al phase and the intermetallic compounds was determined using the EBSP method from polished plating surface, considered part of Al of TiAl ₃ and TiAl ₃ were replaced with Si Ti (Al _1- It was confirmed that the {110} plane and the {102} plane of _X Si _X ) ₃ are parallel to the {110} plane of the Al phase.

Next, after these galvanized steel sheets were degreased, the applied chromate treatment or zinc phosphate treatment of the adhesion amount shown in Table 3 was performed, and then the fine particles were added to 100% by mass of the polyurethane resin produced in Production Example 1. A surface treatment having a film with an adhesion amount of 1.0 g / m ² by applying an aqueous paint containing 30% silica (Snowtex-N: manufactured by Nissan Chemical Industries, Ltd.) and baking it so that the ultimate plate temperature is 150 ° C. A steel plate was produced.

  The evaluation of film adhesion was made by reducing the thickness by 7 mm with an Erichsen test machine, peeling the convex portion with tape, and accepting the case where the film was not peeled, and rejecting the peeled portion.

The corrosion resistance of the processed part was evaluated by the corrosion resistance of the sample after the overhang test. In the overhang test, a 200 × 200 mm blank plate with a 120 mmφ spherical head was used to overhang a height of 35 mm. As a result of measuring the amount of distortion of the sample using a scribed circle, it was found that the height was 33% and the circumference was 9%.
Corrosion resistance was determined by scoring as shown below for the occurrence of white rust after SST120hr for the processed parts after overhanging. A score of 3 or more was accepted.
10: No white rust occurrence 9: White rust occurrence less than 1% 8: White rust occurrence 1% or more and less than 3% 7: White rust occurrence 3% or more and less than 5% 6: White rust occurrence 5% or more and less than 7% 5: White Rust generation 7% to less than 10% 4: White rust generation 10% to less than 15% 3: White rust generation 15% to less than 20% 2: White rust generation 20% to less than 30% 1: White rust generation 30% or more Evaluation The results are shown in Table 3. Table 3 shows the results of applying a chromate film and a zinc phosphate film as the base treatment layer. Nos. 69 and 70 had no surface treatment layer, and the film adhesion and the corrosion resistance of the processed parts were not acceptable. In addition to these, the chromate film and the zinc phosphate film as the base all had good film adhesion and processed part corrosion resistance.

  First, the plated steel sheets shown in Table 2 were prepared, and after these plated steel sheets were degreased, the base treatment agent having the composition shown in Tables 5 to 7 was applied using the chemicals shown in Table 4 and dried in a hot air drying furnace. The ultimate plate temperature during drying was 150 ° C.

An aqueous paint in which 30% of fine silica (Snowtex-N: manufactured by Nissan Chemical Industries, Ltd.) is blended with 100% by mass of the polyurethane resin produced in Production Example 1 is applied on the base treatment, and the ultimate plate temperature is 150 ° C. The surface-treated steel sheet having a film with an adhesion amount of 1.5 g / m ² was produced.

  The evaluation of film adhesion was made by reducing the thickness by 7 mm with an Erichsen test machine, peeling the convex portion with tape, and accepting the case where the film was not peeled, and rejecting the peeled portion.

The corrosion resistance of the processed part was evaluated by the corrosion resistance of the sample after the overhang test. In the overhang test, a 200 × 200 mm blank plate with a 120 mmφ spherical head was used to overhang a height of 35 mm. As a result of measuring the amount of distortion of the sample using a scribed circle, it was found that the height was 33% and the circumference was 9%.
Corrosion resistance was determined by scoring as shown below for the occurrence of white rust after SST120hr for the processed parts after overhanging. A score of 3 or more was accepted.
10: No white rust occurrence 9: White rust occurrence less than 1% 8: White rust occurrence 1% or more and less than 3% 7: White rust occurrence 3% or more and less than 5% 6: White rust occurrence 5% or more and less than 7% 5: White Rust generation 7% to less than 10% 4: White rust generation 10% to less than 15% 3: White rust generation 15% to less than 20% 2: White rust generation 20% to less than 30% 1: White rust generation 30% or more Evaluation The results are shown in Tables 5-7. Tables 5 to 7 show the effects of the resin film composition applied to the resin film as the base treatment layer. No. 138 was out of the scope of the present invention because there was no undercoat layer, and the film adhesion and the corrosion resistance of the processed part were rejected. Except for these, film adhesion and corrosion resistance of the processed parts were all good. In addition, as a kind of silane coupling agent (e), the number 74, 75, 77 which used e1 which has an epoxy group in number 74-77, and e2 which has an amino group independently or used together is comparatively favorable. Corrosion resistance of the processed part was shown.

First, after the plated steel sheets shown in Table 2 were prepared and these plated steel sheets were degreased, the coating chromate treatment with a Cr adhesion amount of 50 mg / m ² , or the composition of No. 74 in Table 3 (Table 5), No. 96 The composition (Table 6), the same ground treatment as the composition of No. 118 (Table 6) is performed at an adhesion amount of 200 mg / m ² , and an aqueous paint having the composition shown in Tables 9 to 12 is applied using the chemicals shown in Table 8. Baking was performed so that the ultimate plate temperature was 150 ° C., and a surface-treated steel sheet having a coating amount of coating shown in Tables 9 to 12 was produced.
Polyurethane resin production example 2
40 parts of a polyester polyol having an average molecular weight of 900 synthesized from adipic acid having a hydroxyl group at the terminal and 1,4-butylene glycol, 160 parts of a 3-mol adduct of bisphenol A propylene oxide having an average molecular weight of 700, 2,2-bis (hydroxy 10 parts of methyl) propionic acid is added to 100 parts of N-methyl-2-pyrrolidone and heated to 80 ° C. to dissolve. Thereafter, 120 parts of hexamethylene diisocyanate is added, heated to 110 ° C. and reacted for 2 hours, and neutralized by adding 10 parts of triethylamine. This solution was dropped into an aqueous solution obtained by mixing 5 parts of ethylenediamine and 570 parts of deionized water under strong stirring to obtain an aqueous urethane resin. The resin has a Tg of 105 ° C., and the weight ratio of the polyester skeleton to the polyether skeleton is polyester skeleton: polyether skeleton = 20: 80.
Polyurethane resin production example 3
230 parts of polyester polyol having an average molecular weight of 900 synthesized from adipic acid having a hydroxyl group at the terminal and 1,4-butylene glycol and 15 parts of 2,2-bis (hydroxymethyl) propionic acid were added to 100 parts of N-methyl-2-pyrrolidone. In addition to the part, warm to 80 ° C. to dissolve. Thereafter, 100 parts of hexamethylene diisocyanate is added, heated to 110 ° C. and reacted for 2 hours, and neutralized by adding 11 parts of triethylamine. This solution was dropped into an aqueous solution obtained by mixing 5 parts of ethylenediamine and 570 parts of deionized water under strong stirring to obtain an aqueous urethane resin. The resin has a Tg of 30 ° C., and the weight ratio of the polyester skeleton to the polyether skeleton is polyester skeleton: polyether skeleton = 100: 0.

  The evaluation of film adhesion was made by reducing the thickness by 7 mm with an Erichsen test machine, peeling the convex portion with tape, and accepting the case where the film was not peeled, and rejecting the peeled portion.

The corrosion resistance of the processed part was evaluated by the corrosion resistance of the sample after the overhang test. In the overhang test, a 200 × 200 mm blank plate with a 120 mmφ spherical head was used to overhang a height of 35 mm. As a result of measuring the amount of distortion of the sample using a scribed circle, it was found that the height was 33% and the circumference was 9%.
Corrosion resistance was determined by scoring as shown below for the occurrence of white rust after SST120hr for the processed parts after overhanging. A score of 3 or more was accepted.
10: No white rust occurrence 9: White rust occurrence less than 1% 8: White rust occurrence 1% or more and less than 3% 7: White rust occurrence 3% or more and less than 5% 6: White rust occurrence 5% or more and less than 7% 5: White Rust generation 7% to less than 10% 4: White rust generation 10% to less than 15% 3: White rust generation 15% to less than 20% 2: White rust generation 20% to less than 30% 1: White rust generation 30% or more welding The property evaluation was performed under the following spot welding conditions.
Applied pressure: 200kgf
Electrode: Cu-Cr alloy, CF type, tip diameter 6mmφ
Energizing time: 10 cycles of continuous welding conditions: nugget forming current I ₀ (when the plate thickness is t, the nugget diameter is 4√t
1.4 times the current value (I _a ), 1 dot / 3
End of continuous welding with a speed of seconds and a pause of 30 seconds every 20 strike points: 0.85 × I _a sample for nugget diameter measurement every 100 strike points
Weld with current value and finish when nugget diameter is less than 4√t
In the end and judgment evaluation, the number of welding points of 500 or more was regarded as acceptable.

  The evaluation results are shown in Tables 9-12. Tables 9-12 investigate the influence of the composition of the film. In Nos. 200 to 205 and 210 to 215, the added portion of the fine silica was outside the range of the present invention, so that the processed portion corrosion resistance was rejected. Nos. 206, 208, 216, and 218 failed in the corrosion resistance of the processed parts because the amount of the coating was less than the lower limit of the present invention. Nos. 207, 209, 217, and 219 failed in weldability because the amount of coating exceeded the upper limit of the present invention. Except for these, good adhesion, processed part corrosion resistance, and weldability were obtained. In addition, as a kind of aqueous resin (a), among numbers 139 to 146, a polyurethane resin a1 having a polyester skeleton and a polyether skeleton (Tg: 85 ° C.), a polyurethane resin a2 having a polyester skeleton and a polyether skeleton ( Nos. 139 and 140 using (Tg 105 ° C.) showed relatively good processed portion corrosion resistance.

First, after the plated steel sheets shown in Table 2 were prepared and these plated steel sheets were degreased, the coating chromate treatment with a Cr adhesion amount of 50 mg / m ² , or the composition of No. 74 in Table 3 (Table 5), No. 96 The same base treatment as the composition (Table 6) and No. 118 (Table 6) was performed at an adhesion amount of 200 mg / m ² , and a water-based paint having the composition shown in Table 13 was applied using the chemicals shown in Table 8, Baking was performed so that the temperature was 150 ° C., and a surface-treated steel sheet having a coating amount as shown in Table 13 was produced.

  The evaluation of film adhesion was made by reducing the thickness by 7 mm with an Erichsen test machine, peeling the convex portion with tape, and accepting the case where the film was not peeled, and rejecting the peeled portion.

Corrosion resistance after machining was evaluated for the corrosion resistance after deep drawing. Using a blank plate having a diameter of 115 mmφ, a cylindrical deep drawing test was performed under the conditions of punch diameter = 50 mmφ, wrinkle holding pressure = 3 t, and deep drawing speed = 30 m / min. Corrosion resistance was determined by scoring the white rust after the CCT 30 cycles on the side surface after deep drawing. In CCT, one cycle was SST (5% salt spray) 2 hr → dry (60 ° C. 30% RH) 4 hr → wet (50 ° C. 95% RH) 2 hr.
10: No white rust occurrence 9: White rust occurrence less than 1% 8: White rust occurrence 1% or more and less than 3% 7: White rust occurrence 3% or more and less than 5% 6: White rust occurrence 5% or more and less than 7% 5: White Rust generation 7% to less than 10% 4: White rust generation 10% to less than 15% 3: White rust generation 15% to less than 20% 2: White rust generation 20% to less than 30% 1: White rust generation 30% or more Evaluation The results are shown in Table 13. Table 13 investigates the influence of the solid lubricant. When the solid lubricant was added in an appropriate amount, the friction coefficient was low, so the processed part corrosion resistance of the drawn part was excellent.

  As described above, according to the present invention, it is possible to produce a surface-treated steel sheet having excellent processed portion corrosion resistance in a Zn-Al-Mg-based plated steel sheet. By expanding the use of high corrosion-resistant steel sheets to members that could not be used due to a decrease in the corrosion resistance of processed parts so far, it becomes possible to greatly contribute to improving the durability of these processed products.

It is a figure which shows an example of the intermetallic compound which exists in Al phase, (a) is the microscope picture (3000 times) of the plating layer of a plated steel plate, (b) is the figure which showed the distribution state of each structure | tissue in a photograph It is. FIG. 1 is a pole figure of the Al phase and the intermetallic compound in FIG. 1, (a) is the (110) pole figure of the Al phase, (b) is the (110) pole figure of the intermetallic compound, (c) is the ( 102) A pole figure.

Claims (24)

On one side or both sides of the steel sheet, Al: 4 to 10% by mass, Mg: 1 to 5% by mass, and the interval between one plane in the lattice direction constituting the lattice plane of Bravay lattice is 2.57 mm to 3.15 mm and the other A plated layer of a plated steel sheet containing an intermetallic compound having a lattice plane with a face spacing of 3.64 mm or more and 4.46 mm or less, and having a Zn alloy plating layer composed of Zn and unavoidable impurities in the balance is [Al / Zn / MgZn ₂ ternary eutectic structure] has a metal structure in which [Al phase] and [MgZn ₂ phase] are mixed, and the lattice plane of Bravay lattice is in [Al phase] An intermetallic compound having a lattice plane in which one plane spacing in the lattice direction is 2.57 mm or more and 3.15 mm or less and the other plane spacing is 3.64 mm or more and 4.46 mm or less is formed as one of the intermetallic compounds. Spacing between 2.57mm and 3.15mm In the following, a plating layer containing the other plane spacing of 3.64 mm or more and 4.46 mm or less and the Al phase {110} plane is parallel to each other, and an undercoat layer is provided thereon as an intermediate layer. And a resin film obtained by applying and drying an aqueous paint containing 5 to 50% by mass of silica particles (b) with respect to 100% by mass of the solid content of the aqueous resin (a) as an upper layer. Is formed with an adhesion amount of 0.2 to 5 g / m ² .
On one or both sides of the steel plate, Al: 4 to 22% by mass, Mg: 1 to 5% by mass, Si: 0.5% by mass or less, and one spacing in the lattice direction constituting the lattice plane of the Bravay lattice is 2. A Zn alloy plating layer containing an intermetallic compound having a lattice plane of 57 to 3.15 mm and the other plane spacing of 3.64 to 4.46 mm, the balance being composed of Zn and inevitable impurities The plated layer of the plated steel sheet has a metal structure in which [Mg ₂ Si phase], [Al phase] and [MgZn ₂ phase] are mixed in the [Al / Zn / MgZn ₂ ternary eutectic structure] substrate In addition, in [Al phase], one surface interval in the lattice direction constituting the lattice surface of the Bravay lattice is 2.57 mm or more and 3.15 mm or less, and the other surface interval is 3.64 mm or more and 4.46 mm or less. an intermetallic compound having a grating surface, the intermetallic compound A plating layer containing a lattice plane in which one surface interval of the object is 2.57 mm or more and 3.15 mm or less, and the other surface interval is 3.64 mm or more and 4.46 mm or less and the {110} plane of the Al phase is parallel. 5 to 50% by mass of silica particles (b) based on 100% by mass of the solid content of the aqueous resin (a) as an upper layer. A surface-treated steel sheet excellent in processed part corrosion resistance, wherein a resin-based film obtained by applying and drying a water-based paint is formed with an adhesion amount of 0.2 to 5 g / m ² .
  The crystal system of the intermetallic compound according to any one of claims 1 to 2 is any one of cubic, tetragonal, orthorhombic, monoclinic, and hexagonal, and has excellent corrosion resistance in a processed part. Surface treated steel sheet.   A surface-treated steel sheet excellent in processed part corrosion resistance, wherein the content of the intermetallic compound according to any one of claims 1 to 3 is 1% by mass or less.   An intermetallic compound having a lattice plane in which the lattice spacing of one of the lattice directions composing the lattice plane of the Bravais lattice is 2.57 mm to 3.15 mm and the other surface spacing is 3.64 mm to 4.46 mm is crystal nuclei. 5. The surface-treated steel sheet having excellent corrosion resistance in the processed part according to claim 1, wherein the primary arm of the dendrite of the Al phase grows in the [110] direction.   The aqueous resin (a) is at least one selected from the group consisting of an aqueous epoxy resin, an aqueous phenol resin, an aqueous polyester resin, an aqueous polyurethane resin, an aqueous acrylic resin, and an aqueous polyolefin resin. 5. A surface-treated steel sheet having excellent processed portion corrosion resistance according to any one of 5 above.   The surface-treated steel sheet having excellent processed portion corrosion resistance according to any one of claims 1 to 6, wherein the aqueous resin (a) is a polyurethane resin having a polyester skeleton portion and a polyether skeleton.   8. The processed portion corrosion resistance according to claim 1, wherein the mass ratio of the polyether skeleton to the polyester skeleton of the polyurethane resin having a polyester skeleton portion and a polyether skeleton is 10:90 to 70:30. Excellent surface-treated steel sheet.   9. The surface-treated steel sheet having excellent processed portion corrosion resistance according to claim 1, wherein the glass transition temperature (Tg) of the aqueous resin (a) is 70 ° C. or higher and 200 ° C. or lower.   The water-based paint further contains at least one crosslinking agent (c) selected from the group consisting of an amino resin, a polyisocyanate compound, its block, an epoxy compound, and a carbodiimide compound, and the solid content of the water-based resin (a) is 100% by mass. The surface-treated steel sheet excellent in processed part corrosion resistance according to any one of claims 1 to 9, wherein the surface-treated steel sheet is contained in an amount of 1 to 40% by mass. The surface-treated steel sheet having excellent processed portion corrosion resistance according to any one of claims 1 to 10, which has a chromate film having a Cr adhesion amount of 5 to 100 mg / m ² as a base treatment layer. The surface treatment excellent in corrosion resistance of a processed part according to any one of claims 1 to 10, wherein the surface treatment layer has a chemical conversion film of a phosphate film having an adhesion amount of 0.2 to 5.0 g / m ^2. steel sheet. It has a resin-type film layer formed by applying and drying a base treatment liquid containing an aqueous resin (d) as a base treatment layer, and the coating amount after drying of the film layer is 10 to 3000 mg / m ² The surface-treated steel sheet excellent in processed part corrosion resistance according to any one of claims 1 to 10.   The aqueous resin (d) is at least one selected from the group consisting of an aqueous epoxy resin, an aqueous phenol resin, an aqueous polyester resin, an aqueous polyurethane resin, an aqueous acrylic resin, and an aqueous polyolefin resin. A surface-treated steel sheet with excellent processed portion corrosion resistance.   The processing part characterized by further containing 1 to 300% by mass of the silane coupling agent (e) in 100% by mass of the aqueous resin (d) in the ground treatment liquid according to claim 13 or 14. Surface-treated steel sheet with excellent corrosion resistance.   The surface excellent in processed part corrosion resistance according to claim 15, wherein the silane coupling agent (e) contains, as a reactive functional group, at least one selected from the group consisting of an epoxy group and an amino group. Treated steel sheet.   The processing characterized by containing 1-300 mass% of polyphenol compounds (f) with respect to 100 mass% of solid content of aqueous resin (d) further in the surface treatment liquid in any one of Claim 13 thru | or 16. Surface-treated steel sheet with excellent corrosion resistance.   The at least 1 sort (g) selected from the group which consists of phosphoric acid and a hexafluoro metal acid is further made into 100 mass% of solid content of aqueous resin (d) to the base-treatment liquid in any one of Claims 13 thru | or 17. A surface-treated steel sheet excellent in processed part corrosion resistance, characterized by containing 0.1 to 100% by mass.   The surface-treated steel sheet having excellent processed portion corrosion resistance according to claim 18, wherein the hexafluorometal acid contains at least one element selected from the group consisting of Ti, Si, Zr, and Nb.   The ground treatment liquid according to any one of claims 13 to 19, further comprising 0.1 to 100% by mass of the phosphate compound (h) with respect to 100% by mass of the solid content of the aqueous resin (d). A surface-treated steel sheet with excellent processed part corrosion resistance.   21. The processed part corrosion resistance according to claim 20, wherein the phosphate compound (h) contains at least one element selected from the group consisting of Mg, Mn, Al, Ca and Ni as a cation component. Excellent surface-treated steel sheet.   The metal oxide particles (i) comprising at least one metal element selected from the group consisting of Si, Ti, Al, and Zr are further added to the ground treatment liquid according to any one of claims 13 to 21 with an aqueous resin ( A surface-treated steel sheet excellent in processed part corrosion resistance, characterized by containing 1 to 300% by mass with respect to 100% by mass of the solid content of d).   The water-based paint applied as an upper layer further contains 1 to 40% by mass of a solid lubricant (j) based on 100% by mass of the solid content of the aqueous resin (a). A surface-treated steel sheet having excellent processed portion corrosion resistance.   The surface-treated steel sheet excellent in processed part corrosion resistance according to claim 23, wherein the solid lubricant (j) is a polyolefin wax having a particle size of 0.1 to 5.0 µm.

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