JP7385119B2 - Surface-treated steel sheet and method for manufacturing surface-treated steel sheet - Google Patents

Description

The present invention relates to a surface-treated steel sheet and a method for manufacturing a surface-treated steel sheet.

A known method is to form an inorganic chemical conversion coating on the surface of a zinc (Zn)-based plating layer to suppress the occurrence of white rust on a plated steel sheet having the Zn-based plating layer (increase corrosion resistance). (For example, Patent Document 1).

Also known is a method of forming an organic resin film on the surface of a Zn-based plating layer to improve the corrosion resistance of a plated steel sheet having the Zn-based plating layer. At this time, phosphate crystals are precipitated on the surface of the plating layer to form a phosphate film, and a film containing an organic resin may be further formed on the surface of the phosphate film (for example, patent Reference 2). Patent Document 2 states that the phosphate film suppresses the occurrence of white rust, improves the adhesion of the organic resin film, and improves the effectiveness of the Zn-based plated steel sheet by scattering light due to the crystal particles of the phosphate. It is described that it has the effect of reducing gloss (hereinafter, low gloss of a plated steel sheet is also simply referred to as "high anti-glare property").

Japanese Patent Application Publication No. 11-61431 Japanese Patent Application Publication No. 2012-021207

As described in Patent Document 1, the corrosion resistance of a plated steel sheet can be improved by forming a chemical conversion coating. However, depending on the use of the plated steel sheet, it is also required to improve the anti-glare properties of the plated steel sheet.

Further, as described in Patent Document 2, the anti-glare properties of a plated steel sheet can be improved by crystals of phosphate. However, in this method, after forming the phosphate film, it is necessary to form an organic resin film to improve corrosion resistance. In response, there is a demand for improving the productivity of plated steel sheets by reducing the number of steps.

In view of these circumstances, the present invention provides a surface-treated plated steel sheet (hereinafter also simply referred to as a "surface-treated steel sheet") that has good productivity and high anti-glare properties, and a surface-treated steel sheet that has good productivity and high anti-glare properties. Its purpose is to provide a manufacturing method.

One aspect of the present invention for solving the above problems includes a steel plate, an Al-containing Zn-based plating layer disposed on the surface of the steel plate, and an Al-containing Zn-based plating layer that partially covers the surface of the Al-containing Zn-based plating layer. The present invention relates to a surface-treated steel sheet having a 60° gloss value of 80 or less.

Further, another aspect of the present invention for solving the above problems includes a step of preparing a plated steel sheet in which an Al-containing Zn-based plating layer is arranged on the surface of the steel sheet, and a step of preparing a plated steel sheet in which an Al-containing Zn-based plating layer is arranged on the surface of the steel sheet. a step of applying a treatment liquid containing an acid salt and having a pH of 1.5 or more and 3.0 or less to form Al-containing phosphate compound particles on the surface. Relating to a manufacturing method.

According to the present invention, a surface-treated steel sheet with good productivity and high anti-glare properties, and a method for manufacturing the surface-treated steel sheet are provided.

FIG. 1 shows surface-treated steel sheet No. 1 in an example. These are the AES measurement results of granules (phosphate compound particles) formed on the surface of the Al-containing zinc-based plating layer of No. 9. FIG. 2A shows surface-treated steel sheet No. 1 in the example. 2B is an enlarged photograph of the surface of No. 9, and FIG. 2B is an enlarged photograph of the surface of No. 9. 24 is an enlarged photograph of the surface of an inorganic film formed by No. 24.

An embodiment of the present invention will be described below.

1. Surface Treated Steel Sheet The surface treated steel sheet according to the present embodiment includes a plated steel plate and phosphate compound particles arranged on the surface of the plated steel plate. Each component of the chemical conversion treated steel sheet according to this embodiment will be explained below.

[Plated steel sheet]
The plated steel sheet is an Al-containing Zn-based plated steel sheet that has a zinc (Zn)-based plating layer containing aluminum (Al-containing Zn-based plating layer).

Examples of the steel plate (substrate steel plate) serving as the base of the plated steel plate include low carbon steel, medium carbon steel, high carbon steel, and alloy steel. It is preferable that the base steel sheet is a deep drawing steel sheet such as low carbon Ti-added steel or low carbon Nb-added steel from the viewpoint of improving the workability of the chemically treated steel sheet.

The Al-containing Zn-based plating layer is a Zn-based plated steel sheet whose corrosion resistance is improved by containing 0.05 to 60% by mass of aluminum. The Al-containing Zn-based plating layer may contain 0.5 to 4.0% by mass of magnesium (Mg), silicon (Si), etc. in order to further improve corrosion resistance.

Examples of the Al-containing Zn-based plating layer include a hot-dip 5% Al-Zn plated steel sheet using a Zn alloy containing approximately 5% by mass of Al, a hot-dip Al-Mg-Zn plated steel sheet using a Zn alloy containing Al and Mg, These include hot-dip Al-Mg-Si-Zn-plated steel sheets using a Zn alloy containing Al, Mg, and Si, hot-dip 55% Al-Zn-plated steel sheets using a Zn alloy containing approximately 55% by mass of Al, and the like.

Examples of the steel plate (substrate steel plate) serving as the base of the plated steel plate include low carbon steel, medium carbon steel, high carbon steel, and alloy steel. It is preferable that the base steel sheet is a deep drawing steel sheet such as low carbon Ti-added steel or low carbon Nb-added steel from the viewpoint of improving the workability of the chemically treated steel sheet.

The thickness of the plated steel sheet can be appropriately determined depending on the use of the surface-treated steel sheet, and is, for example, 0.2 mm or more and 6.0 mm or less. The plated steel plate may be, for example, a flat plate or a corrugated plate, and the planar shape of the plated steel plate may be rectangular or a shape other than a rectangle.

[Phosphate compound particles]
The phosphate compound particles are particles containing phosphate and Al that are dispersed and arranged on the surface of the Al-containing Zn-based plating layer. In this embodiment, the dispersed phosphate compound particles scatter light, thereby improving the anti-glare properties of the plated steel sheet.

The phosphate is not particularly limited as long as it is a compound having a phosphate anion and can form poorly water-soluble crystals. Examples of the phosphates include aluminum phosphate, magnesium phosphate, manganese phosphate, zinc phosphate, iron phosphate, zinc iron phosphate, zinc calcium phosphate, and the like. However, a part of the above-mentioned phosphate is aluminum phosphate.

The above Al is an Al atom originating from the Al-containing Zn-based plating layer, and forms a salt (aluminum phosphate) with phosphoric acid contained in the treatment liquid for forming phosphate compound particles. . In this embodiment, as will be described later, a treatment solution with an increased amount of phosphate than a conventional chemical conversion treatment solution and a decreased amount of nitrate ions than a conventional phosphate treatment solution is used. Forming acid salt compound particles. In the above treatment solution, the Al ions (Al ³⁺ ) eluted from the Al-containing Zn-based plating layer are not consumed in the reduction reaction of nitrate ions (NO ₃ ⁻ ) unlike conventional phosphate treatment solutions. Instead, it forms a salt with phosphate ions (PO ₃ ^4- ), crystallizes, and precipitates. In this way, in this embodiment, the improvement in corrosion resistance achieved by conventional chemical conversion treatment liquids and the improvement in antiglare properties due to the formation of phosphate compound particles are achieved with a single treatment liquid.

The content of Al in the phosphate compound particles is preferably 3% by mass or more and 40% by mass or less, and 5% by mass or more and 35% by mass or less based on the total mass of the phosphate compound particles. It is more preferable that the amount is at least 5% by mass and not more than 30% by mass. The content of Al can be measured using an Auger electron spectroscopy (AES) analyzer.

Note that when forming phosphate compound particles using the above treatment liquid, Zn ions (Zn ²⁺ ) are also eluted from the Al-containing Zn-based plating layer in addition to Al ions. The eluted Zn ions may also form salts with phosphate ions, crystallize, and precipitate like Al ions. Therefore, it is preferable that the phosphate compound particles also contain a trace amount of Zn in addition to the Al.

The average particle size of the phosphate compound particles is preferably 0.5 μm or more and 10.0 μm or less. When the average particle size is 0.5 μm or more, the antiglare improvement effect of the phosphate compound particles can be more fully exhibited. When the average particle size is 10.0 μm or less, cohesive failure of the phosphate compound particles is less likely to occur when the surface-treated steel sheet according to the present embodiment is formed. From the above viewpoint, it is more preferable that the average particle size of the phosphate compound particles is 1.0 μm or more and 6.0 μm or less.

Furthermore, from the viewpoint of improving the adhesion of the phosphate compound particles, it is preferable that the base portions of the phosphate compound particles dig into the Al-containing Zn-based plating layer. The average depth of the crystal grains of the phosphate compound particles that bite into the plating layer is preferably 0.05 μm or more. The depth of penetration of the phosphate compound particles can be determined by removing the phosphate crystal particles using a diammonium chromate aqueous solution and then observing the traces of the phosphate crystal particles using a scanning laser microscope. It can be measured by

Further, it is preferable that the adhesion amount of the phosphate compound particles is 36 mg/m ² or more and 210 mg/m ^{2 or} less in terms of P atoms. When the amount of adhesion is 36 mg/m ² or more, the phosphate compound particles can more effectively improve anti-glare properties and improve corrosion resistance. When the adhesion amount is 180 mg/m ² or less, cohesive failure of the phosphate compound particles is unlikely to occur when the surface-treated steel sheet according to the present embodiment is formed. From the above viewpoint, the adhesion amount of the phosphate compound particles is more preferably 36 mg/m ² or more and 180 mg/m ² or less, and even more preferably 60 mg/m ² or more and 140 mg/m ² or less. The amount of attached phosphate compound particles can be measured using an elemental analyzer such as a fluorescent X-ray analyzer or an ICP analyzer.

Further, it is preferable that the phosphate compound particles cover 11% or more of the surface of the Al-containing Zn-based plating layer on the surface on which the phosphate compound particles are formed. When the coverage of the surface of the plating layer is 11% or more, the effects of improving anti-glare properties and improving corrosion resistance due to the phosphate compound particles can be more fully exhibited. The upper limit of the coverage is not particularly limited, but from the viewpoint of suppressing cohesive failure of the phosphate compound particles during molding, it can be set to 98%. From the above viewpoint, the coverage is more preferably 11% or more and 60% or less, even more preferably 15% or more and 40% or less, and particularly preferably 15% or more and 25% or less. The coverage rate of the surface of the Al-containing Zn-based plating layer by the phosphate compound particles can be measured by image analysis of a scanning electron microscope (SEM) photograph of the surface of the Al-containing Zn-based plating layer.

[Inorganic film]
In the surface-treated steel sheet according to the present embodiment, an inorganic film formed by the treatment liquid may be disposed on the surface of the Al-containing Zn-based plating layer. Typically, the surface-treated steel sheet according to this embodiment has the above-mentioned inorganic film as a continuous film disposed on the surface of the Al-containing Zn-based plating layer, and the inorganic film is disposed on the surface of the Al-containing Zn-based plating layer. The phosphate compound particles are formed inside the inorganic coating or protruding from the surface of the inorganic coating.

The inorganic film is made of valve metals such as titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), molybdenum (Mo), and tungsten (W). , preferably contains one or more metal elements. These valve metals are contained in the inorganic film as salts such as oxides, hydroxides, or fluorides.

In the present embodiment, it is preferable that the inorganic film contains Ti or Zr, since these are particularly effective in improving corrosion resistance.

Further, on the surface of the Al-containing Zn-based plating layer, the ratio of the amount of P deposited by the phosphate compound particles to the amount of Ti and Zr deposited by the inorganic film (P/(Ti+Zr)) is a mass ratio, It is preferable that it is 1.2 or more. When the amount of P relative to Ti and Zr is within the above range, a more sufficient amount of the phosphate compound particles is formed by applying the treatment liquid, so that the phosphate compound particles have an effect of improving anti-glare properties. is played well. From the above viewpoint, the ratio (P/(Ti+Zr)) is more preferably 1.2 or more and 3.0 or less, particularly preferably 1.5 or more and 2.5 or less.

The amount of Ti and Zr deposited by the inorganic film is preferably 30 mg/m ² or more in terms of Ti and Zr atoms. When the amount of adhesion is 30 mg/m ² or more, the effect of improving corrosion resistance due to Ti or Zr acting as a resistor against electron movement can be more fully exhibited. From the above viewpoint, the amount of Ti deposited is more preferably 30 mg/m ² or more and 70 mg/m ² or less, and even more preferably 30 mg/m ² or more and 60 mg/m ² or less. The amount of Ti and Zr deposited can be measured using a fluorescent X-ray analyzer, an ICP analyzer, or the like.

[Organic film]
The surface-treated steel sheet according to the present embodiment may have an organic film containing an organic resin as a main component, covering the phosphate compound particles (and the inorganic film).

The organic resin may be any organic resin commonly used for surface treatment of zinc-plated steel sheets, and can be appropriately selected from, for example, urethane resins, fluororesins, acrylic resins, polyester resins, and the like. An organic film containing these organic resins can improve the corrosion resistance and workability of the coated steel sheet.

Among these, from the viewpoint of further improving corrosion resistance and processability, the organic resin is preferably a urethane resin or a polyester resin, and more preferably a urethane resin.

Preferably, the organic film contains one or more metal elements among the valve metals. These valve metals are contained in the organic film as salts such as oxides, hydroxides, or fluorides.

The thickness of the organic film is preferably 3.0 μm or more. When the film thickness is 3.0 μm or more, it becomes difficult for corrosion factors that have penetrated the organic film to reach the plating layer, and the corrosion resistance of the surface-treated steel sheet can be sufficiently improved. Although the upper limit of the thickness of the organic film is not particularly limited, it can be set to 15 μm.

The organic film may be a colored film containing an organic pigment, but when it is a clear film, the effect of improving anti-glare properties by the phosphate compound particles is remarkable.

The surface-treated steel sheet having the above configuration has a reduced gloss level due to the phosphate compound particles that are dispersed on the surface of the Al-containing Zn-based plating layer and partially cover the surface. As a result, the 60° gloss value of the surface-treated steel sheet is 80 or less. The 60° gloss value is preferably 60 or less, more preferably 50 or less, and even more preferably 40 or less. The above 60° gloss value is a value measured in accordance with JIS K 5600-4-5 (1999).

2. Method for manufacturing surface-treated steel sheet The above-mentioned surface-treated steel sheet includes applying a treatment liquid containing phosphate and having a pH of 1.5 to 3.0 to the surface of the Al-containing Zn-based plating layer, It can be manufactured by drying the applied treatment liquid.

The solvent of the treatment liquid is preferably an aqueous medium from the viewpoint of explosion protection during production of chemically treated steel sheets. The aqueous medium is a liquid medium containing water as a main component, and is, for example, water or a mixture of water and a water-soluble organic solvent. The content of the liquid medium can be appropriately determined within the above-mentioned solid content concentration range suitable for application of the chemical conversion treatment liquid.

The phosphoric acid of the phosphate salt contained in the treatment liquid may be a normal phosphoric acid such as orthophosphoric acid, or a complex phosphoric acid such as pyrophosphoric acid. Examples of phosphate cations include hydrogen ions, alkali metal ions, alkaline earth metal ions, ammonium ions, manganese ions, aluminum ions, titanium ions, zirconium ions, hafnium ions, and zinc ions.

The content of the phosphate in the treatment liquid is preferably 12/L or more and 30 g/L or less in terms of P atoms. By setting the content of the phosphate to 12 g/L or more, a sufficient amount of the phosphate compound particles can be formed, and the anti-glare properties of the surface-treated steel sheet to be produced can be more fully improved. . From the above viewpoint, the content of the phosphate is more preferably 15 g/L or more and 25 g/L or less.

Further, it is preferable that the treatment liquid contains the above-mentioned valve metal, particularly Ti or zirconium (Zr). The above valve metal may be added as a salt such as an oxide, hydroxide or fluoride. For example, when containing Ti, the above treatment liquid contains K _n TiF ₆ (K: alkali metal or alkaline earth metal, n: 1 or 2), K ₂ [TiO(COO) ₂ ], (NH ₄ ). ₂ Ti salts such as TiF ₆ , TiCl ₄ , TiOSO ₄ , Ti(SO ₄ ) ₂ and Ti(OH) ₂ or Zr salts such as (NH ₄ )ZrF ₆ may be added.

The content of the valve metal (particularly Ti and Zr) in the treatment liquid is preferably 5.0 g/L or more and 20.0 g/L or less in terms of valve metal atoms. By setting the content of the valve metal to 5.0 g/L or more, a sufficient amount of the inorganic film can be formed, and the corrosion resistance of the surface-treated steel sheet to be produced can be more fully improved. From the above viewpoint, the content of the valve metal is more preferably 7.0 g/L or more and 15.0 g/L or less.

When the treatment liquid contains a fluorine compound, Al ions can be easily eluted from the Al-containing Zn-based plating layer, and Al-containing phosphate compound particles can be more fully generated. From the above viewpoint, the content of fluorine (F) in the treatment liquid is preferably 5 g/L or more, more preferably 5 g/L or more and 50 g/L or less, and 10 g/L or more and 25 g/L or less. It is more preferable that The above-mentioned fluorine may be contained in the treatment liquid by adding a fluoride to the valve metal, or may be contained in a treatment liquid containing a fluoride other than these.

As described above, in this embodiment, unlike the conventional phosphate treatment that promotes crystallization of phosphate by nitrate ions, phosphate compound particles are treated by Al ions eluted from the Al-containing Zn-based plating layer. Promote formation. Therefore, the treatment liquid may have a reduced content of nitrate ions, for example, the content of nitrate ions can be 1 g/L or less, preferably 0.1 g/L or less.

Further, the pH of the treatment liquid is preferably 1.5 or more and 3.0 or less. Conventional processing solutions containing organic acids such as nitric acid usually have a pH smaller than this. On the other hand, the above treatment solution precipitates an Al-containing phosphate compound produced by the reaction between Al derived from the Al-containing Zn-based plating layer and phosphorus in the treatment solution, and deposits it on the surface of the plating layer. It is attached in the form of particles. When the pH is less than 1.5, the Al-containing phosphate compound is dissolved in the treatment liquid and does not precipitate, making it difficult to form phosphate compound particles. In addition, if the above-mentioned treatment liquid contains fluorine (F) in the above-mentioned content, Al ions will be easily eluted from the Al-containing Zn-based plating layer even if the pH is 1.5 or more and 3.0 or less. , a sufficient amount of phosphate compound particles can be produced.

Further, the treatment liquid may further contain tannic acid, a silane coupling agent, and colloidal silica in order to further improve the corrosion resistance of the surface-treated steel sheet. Further, the treatment liquid may further contain pigments, metal flakes, etc. in order to adjust the appearance of the surface-treated steel sheet.

Further, the treatment liquid may further contain a rheology control agent, an etching agent, a phosphate or an inorganic compound other than the valve metal, a lubricant, and the like.

The etching agent activates the surface of the plated steel sheet and contributes to improving the adhesion of the chemical conversion film to the plated steel sheet. Examples of etchants include fluoride. The above-mentioned inorganic compound densifies the chemical conversion coating and contributes to improving the water resistance of the chemical conversion coating. Examples of inorganic compounds include oxides or phosphates of Mg, Ca, Sr, W, Mn, B, Si or Sn. The above lubricant enhances the lubricity of the chemical conversion coating and contributes to improving the workability of the chemical conversion treated steel sheet. Examples of lubricants include inorganic lubricants such as molybdenum disulfide and talc.

The treatment liquid is preferably applied to the surface of the Al-containing Zn-based plating layer by a method such as a roll coating method, a spin coating method, or a spray method. Immersing the plated steel sheet in the treatment liquid is not preferable because a large amount of the plating layer is dissolved and a large amount of sludge is added to the treatment liquid.

Drying of the chemical conversion treatment liquid applied to the surface of the plated steel sheet can be carried out at room temperature, but from the viewpoint of productivity (continuous operation), it is preferably carried out at a temperature of 50°C or higher, and it is preferably carried out at a temperature of 100°C or higher. It is more preferable. The drying temperature is preferably 300° C. or lower from the viewpoint of preventing thermal decomposition of the components in the chemical conversion treatment liquid.

Thereafter, if necessary, the organic film may be further formed to cover the formed phosphate compound particles (and the inorganic film).

Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited by these Examples.

1. Experiment 1
[Production of plated steel sheets A to plated steel sheets C]
A hot-dip Zn-plated steel sheet (plated steel sheet A), which is a cold-rolled steel sheet (SPCC) subjected to hot-dip zinc plating with hot-dip Zn, was prepared. The hot-dip Zn-plated steel sheet usually contains about 0.1% by mass of Al. In addition, a hot-dip 6% Al-3% Mg-Zn plated steel sheet (plated steel sheet B) obtained by applying hot-dip alloy plating of a hot-dip Zn-6% by mass Al-3% by mass Mg alloy to SPCC was prepared. In addition, a hot-dip 11% Al-3% Mg-Zn plated steel sheet (plated steel sheet C) obtained by applying hot-dip alloy plating of a hot-dip Zn-11% by mass Al-3% by mass Mg alloy to SPCC was prepared. The plate thicknesses of plated steel plates A to plated steel plates C were all 3.2 mm, and the coating weight on one side of plated steel plates A to plated steel plates C was all 60 g/m ² .

[Preparation of treatment liquid]
A processing solution containing the P source and Ti source listed in Table 1 and other additives was prepared.

Any one of treatment liquids 1 to 7 was applied to the surface of the plating layer of plated steel sheets A to C using a roll coater. Thereafter, the plated steel plate was dried at 140° C. without washing with water to form phosphate compound particles on the surface of the plated layer. Surface-treated steel sheets with different amounts of phosphate and Ti or Zr compounds deposited were produced by varying the amount of each treatment liquid applied using a roll coater.

[evaluation]
(1) Coverage rate of surface by phosphate compound particles The surface of each surface-treated steel sheet was imaged with a scanning electron microscope (SEM), and the obtained image was analyzed using image analysis software (ImageJ) to determine whether the plating The proportion of particulate matter (coverage) on the surface of the layer was determined.

(2) Appearance The 60° specular gloss G ₆₀ of the surface-treated side of each surface-treated steel sheet was measured in accordance with the "Specular gloss - measurement method" specified in JIS Z8741, and was determined by Co., Ltd. Measurement was performed using a gloss meter GMX-203 manufactured by Murakami Color Research Institute. Based on the measured glossiness, the appearance of the surface-treated steel sheet was evaluated according to the following criteria.
◎: _G60 is less than or equal to 60 ○: _G60 is more than 60 and less than 80 △: _G60 is more than 80 and less than 100 ×: _G60 is more than 100

(3) Corrosion resistance The end faces of each surface-treated steel plate were sealed, and a 5% NaCl aqueous solution at 35° C. was continuously sprayed on the surface-treated surface in accordance with JIS Z 2371 (year). After continuing the salt water spraying for 120 hours, the surface of the sprayed surface-treated steel sheet was observed, and the area ratio of the area where white rust was generated was measured. Based on the measured area ratio, the corrosion resistance of the flat portion of the surface-treated steel sheet was evaluated according to the following criteria.
◎: The area ratio where white rust has occurred is 5% or less. ○: The area ratio where white rust has occurred is more than 5% and no more than 10%. △: The area ratio where white rust has occurred is more than 10% and no more than 20%. Yes ×: The area ratio where white rust has occurred is over 20%

FIG. 1 shows surface-treated steel sheet No. These are the AES measurement results of granules (phosphate compound particles) formed on the surface of the Al-containing zinc-based plating layer of No. 9. As is clear from FIG. 1, it can be seen that this particulate material is a phosphate containing Al and Zn. In addition, as a result of AES measurement, it was found that other particulates formed in this experiment were also phosphates containing Al and Zn.

FIG. 2A shows surface-treated steel sheet No. 2B is an enlarged photograph of the surface of No. 9, and FIG. 2B is an enlarged photograph of the surface of No. 9. 24 is an enlarged photograph of the surface of an inorganic film formed by No. 24. As is clear from FIGS. 2A and 2B, the surface-treated steel sheet produced in this experiment had granules that partially covered the surface of the Al-containing zinc-based plating layer, which resulted in a decrease in _G60 . I understand.

Furthermore, as is clear from Table 2, by adjusting the composition and application amount of the treatment liquid, the G ₆₀ of the surface-treated steel sheet can be reduced to 80 or less, and the anti-glare properties of the surface-treated steel sheet can be sufficiently improved. Ta.

The chemical conversion treated steel sheet has sufficiently improved anti-glare properties and is therefore useful in various uses such as exterior building materials and interior building materials. For example, the above-mentioned chemically treated steel sheets can be used for roofing materials and exterior materials of buildings, steel pipes and sections for vinyl greenhouses or agricultural greenhouses, supports, beams, etc., transportation members, sound insulation walls, soundproof walls, sound absorption walls, snow prevention walls, etc. It can be suitably used for various purposes such as guardrails, handrails, protective fences, supports, railway vehicle parts, overhead wire parts, electrical equipment parts, safe environment parts, structural parts, solar mounts, and air conditioner outdoor units. .

Claims (9)

steel plate and
an Al-containing Zn-based plating layer disposed on the surface of the steel plate;
Al-containing phosphate compound particles that are distributed over the entire surface of the Al- containing Zn-based plating layer and partially cover the surface of the Al-containing Zn-based plating layer. ,
The 60° gloss value of the surface is 80 or less,
Surface treated steel plate. The surface-treated steel sheet according to claim 1, wherein the phosphate compound particles cover an area of 11% or more of the surface of the Al-containing Zn-based plating layer. The surface-treated steel sheet according to claim 1 or 2, wherein the phosphate compound particles contain Zn. further comprising an inorganic film containing Ti or Zr, which is a continuous film disposed on the surface of the Al-containing Zn-based plating layer,
The phosphate compound particles are formed inside the inorganic coating or protruding from the surface of the inorganic coating,
The surface-treated steel sheet according to any one of claims 1 to 3. The ratio of the amount of phosphorus (P) attached to the amount of titanium (Ti) and zirconium (Zr) attached on the surface of the Al-containing Zn-based plating layer (P/(Ti+Zr)) is 1.2 or more in terms of mass ratio. The surface-treated steel sheet according to claim 4. The surface-treated steel sheet according to claim 4 or 5, wherein the amount of titanium (Ti) and zirconium (Zr) deposited on the surface of the Al-containing Zn-based plating layer is 30 mg/m ² or more. A step of preparing a plated steel sheet in which an Al-containing Zn-based plating layer is arranged on the surface of the steel sheet;
A treatment liquid containing phosphate and having a pH of 1.5 or more and 3.0 or less is applied to the surface of the Al-containing Zn-based plating layer to coat the surface with Al-containing phosphate compound particles. a step of forming the
A method for manufacturing a surface-treated steel sheet, comprising: The method for manufacturing a surface-treated steel sheet according to claim 7, wherein the treatment liquid further contains Ti or Zr. The surface-treated steel sheet according to claim 8, wherein the ratio of the mass of phosphorus (P) to the mass of titanium (Ti) and zirconium (Zr) in the treatment liquid (P/(Ti+Zr)) is 1.2 or more. Production method.