The present invention relates to a surface treated steel sheet having a coating on the surface.
BACKGROUND
[0002]
　Conventional, zinc-plated steel sheets, household appliances, building materials, have been used in various fields such as automobiles. As a method of improving resistance to corrosion, and the like of the galvanized steel sheet, a technique of forming a film on the surface of the galvanized steel sheet is widely used (for example, see Patent Documents 1 to 6).
CITATION
Patent Document
[0003]
Patent Document 1: JP 2011-183307 Patent Publication
Patent Document 2: JP 2003-13252 JP
Patent Document 3: Japanese Patent No. 5642082 discloses
Patent Document 4: JP 2012-92444 JP
Patent Document 5: WO 2011 / 122119 Patent
Patent Document 6: JP 2011-225967 Patent Publication
Summary of the Invention
Problems that the Invention is to Solve
[0004]
　Is resistant condensation whitening One of the important characteristics required for the surface appearance quality of the surface treated steel sheet used in unpainted. The condensation whitening (white rust), the contact portion between the dew condensation water generated on the surface of the surface treated steel sheet is a phenomenon in which whitening. However, galvanized steel sheet having a coating on a conventional surface was not sufficiently suppressed condensation whitening. Further, in the galvanized steel sheet having a coating on the conventional surface, it has been required to further improve the corrosion resistance.
[0005]
　The present invention has been made in view of such circumstances, and an object thereof is to provide a surface treated steel sheet having excellent resistance to condensation whitening resistance and corrosion resistance.
Means for Solving the Problems
[0006]
　The present inventors, in order to solve the above problems, intensive studies. The present inventors first conducted a study about the components constituting the film, P, Ti, V, coatings formed using the process agent containing Si and polyurethane resins to improve the resistance to condensation whitening resistance and corrosion resistance heading was.
[0007]
　Furthermore, the present inventors have polyurethane resin as a finely particulate, by uniformly dispersing in the film, V, by uniformly dispersed coating of a component having a corrosion inhibiting effect of Ti or the like, further It focused on the possibility of improving the resistance to condensation whitening resistance and corrosion resistance made. Then, the present inventors have found that by employing a special method of using acetic acid as a component of the processing agent, was confirmed for the first time coating prepared by uniformly dispersing the polyurethane resin in the form of particles in the composition system. Furthermore, surprisingly, the present inventors have found that this so-formed film is not only possible to express excellent condensation whitening resistance and corrosion resistance, the stack whitening occurring in a completely different environment from the condensation whitening It was found to exhibit a high tolerance even for.
　The gist of the present invention is as follows.
[0008]
(1) and the steel plate, and the plating layer containing zinc formed on the surface of the steel sheet, and a film formed on the plating layer,
　the coating, the average particle diameter of 20nm or 200nm or less of the polyurethane resin a resin component comprising a resin particle composed, and a P and Ti and V and Si,
　wherein a phosphate conversion 2.5% by weight or more 7.5 wt% or less of P in the coating during,
　the in the cross section of the coating area ratio of the resin component is not less than 80% to 35%,
　it said has film the resin particles in the dispersion, and the maximum value of the distance between the centers of gravity of the resin particles, the average particle diameter of the resin particles it is 3.0 times or less, surface-treated steel sheet.
[0009]
(2) the surface roughness of the film (Ra) is 1nm or more 10nm or less, surface-treated steel sheet according to (1).
(3) surface roughness of the steel sheet (Ra) is 0.1μm or more 2μm or less, surface-treated steel sheet according to (1) or (2).
(4) The plating layer containing antimony, surface treated steel sheet according to any one of (1) to (3).
(5) the resin component comprises an olefinic wax and / or a phenolic resin, a surface treated steel sheet according to any one of (1) to (4).
[0010]
(6) said Si in the coating SiO 2 40 wt% 10 wt% or more in terms of
　less, the Ti or 1.7 wt% 2.4 wt% or less,
　V to 0.70 mass% to 0.90 mass% hereinafter
　wherein, the mass ratio between Ti and V (Ti / V) is 2.1 to 2.9 or less, surface-treated steel sheet according to any one of (1) to (5).
Effect of the invention
[0011]
　Above, the surface treated steel sheet of the present invention have excellent resistance to condensation whitening resistance and corrosion resistance.
[0012]
　The surface-treated steel sheet of the present invention is provided with the above configuration also has a better resistance to stack whitening resistance surprisingly. Here, coil or the like is transported in a high-temperature and high-humidity environment of the surface-treated steel plate is an "anti-stack whitening resistance" indicates the corrosion resistance when stored. Stack whitening high temperature governing the rate of reaction, whereas the amount of water is less a reaction field, condensation whitening is different in that water is a reaction field at a room temperature is large, it is possible to improve both resistance is a surprising effect was.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013]
It is a schematic diagram for explaining an example of a cross-sectional structure of the surface treated steel sheet of FIG. 1 embodiment.
FIG. 2 is a schematic cross-sectional view of a film for explaining a method of comparing the average particle size of the inter-centroid distance and the resin particles.
3 is a schematic cross-sectional view of a film for explaining a method of comparing the average particle size of the inter-centroid distance and the resin particles.
A [4] bright field obtained by observing the cross section of the surface-treated steel sheets of Examples 4 with a scanning transmission electron microscope (STEM) (STEM-BF) image.
5 is a high-angle scattering annular dark-field (STEM-HAADF) image obtained by observing a cross section of the scanning transmission electron microscope of the surface treated steel sheet of Example 4 (STEM).
6 is a high-angle scattering annular dark-field (STEM-HAADF) image obtained by observing a cross section of the scanning transmission electron microscope of the surface treated steel sheet of Example 4 (STEM).
7 is a bright-field (STEM-BF) image obtained by observing the surface treated steel sheet of the cross-section of the scanning transmission electron microscope of Comparative Example 11 (STEM).
8 is a bright-field (STEM-BF) image obtained by observing the surface treated steel sheet of the cross-section of the scanning transmission electron microscope of Comparative Example 11 (STEM).
DESCRIPTION OF THE INVENTION
[0014]
　Reference will now be described in detail preferred embodiments of the present invention. In the specification and the drawings, components having substantially the same function and structure are a repeated explanation thereof by referring to the figures. In the present specification, the description of "a ~ b" as numerical range, it is described that is intended to also include upper and lower limits not only the range between a and b. That is, in this specification, wherein comprising "a ~ b" is interpreted to mean "a higher b less".
[0015]
1. Surface treated steel sheet
　Figure 1 is a schematic diagram for explaining an example of a sectional structure of the surface treated steel sheet of the present embodiment.
　Surface treated steel sheet 10 shown in FIG. 1 has a steel plate 1, the plating layer 2 containing zinc formed on the surface 1a of the steel sheet 1, and a film 3 formed on the plating layer 2.
　In the surface treated steel sheet 10 shown in FIG. 1, will be described with reference to a case where only the surface 1a side of the one surface of the steel sheet 1 plating layer 2 and the film 3 is formed as an example, a surface treated steel sheet of the present invention, the steel sheet the plating layer and coating on both sides may be formed. The plating layer 2 is, when it is formed on both surfaces of the steel plate 1, coating 3 may be formed only on one side, may be formed on both surfaces.
[0016]
1.1 steel sheet
　in the present embodiment, the steel plate 1 formed of the plating layer 2 on the surface 1a, but is not particularly limited. For example, the steel plate 1, ultra-low C-type (ferrite-based tissue), Al-k type (tissue containing pearlite in the ferrite), 2-phase structure type (e.g., tissue including martensite in the ferrite, bainite in ferrite tissue including), strain-induced transformation type (tissue containing retained austenite in the ferrite), such a fine crystalline (ferrite-based organization), may be used any type of steel.
[0017]
　Surface roughness Ra of the steel sheet 1 (Test length: 1 inch) (. Hereinafter, also referred to as "Ra-S") is not particularly limited, preferably 0.1 ~ 2 [mu] m. Film 3 as a result of the polyurethane resin is uniformly dispersed, it has a uniform distribution of each component in the coating 3, diffused reflection of incident light is relatively suppressed in this order in the film 3. Further, the film 3, even when a relatively small thickness, for example 500nm thick, exhibits excellent corrosion resistance and condensation whitening resistance and stack whitening resistance. Thus uniform component distribution in a film 3, when a relatively thickness is small, depending on the composition of the film 3, the interference pattern on the surface treated steel sheet 10 may occur.
[0018]
　In contrast, the present inventors have found that the roughness of the surface of the steel plate 1 within a predetermined range, that control the shape of the reflecting surface of the plating layer 2 side of the film 3, to suppress the interference pattern heading was. Specifically, The surface roughness of the steel sheet 1 (Ra-S) (Test length: 1 inch) When is 0.1μm or more, it can avoid expressing the interference pattern on the surface treated steel sheet 10, good appearance can be obtained. Surface roughness of the steel sheet 1 (Ra-S) is more preferably 0.2μm or more, and still more preferably 0.3μm or more.
[0019]
　On the other hand, the surface roughness of the steel sheet 1 (Ra-S) (Test length: 1 inch) is the is 2μm or less, a part of the steel plate 1 due to the large surface roughness of the steel sheet 1 through the coating 3 from being exposed, it can be prevented more reliably. Accordingly, excellent corrosion resistance can be obtained more reliably. Surface roughness of the steel sheet 1 (Ra-S) is more preferably 1.5μm or less, more preferably 1.0μm or less.
　The surface roughness of the steel sheet 1 (Ra-S) (Test length: 1 inch) and the surface of the coating 3 the surface of the surface treated steel sheet 10 plated layer 2 and the film 3 on the surface 1a of the steel sheet 1 is formed roughness and (Ra). In the present specification, the surface roughness Ra is obtained on measuring in conformity with JIS B 0601.
[0020]
1.2 plating layer
　plated layer 2 contains zinc, is formed on one or both sides of the surface of the steel sheet 1. The plated layer containing zinc, and pure zinc plated layer, the zinc content is meant to include a 40% by mass or more of zinc alloy plating layer. The zinc alloy plating layer, for example, 55% Al-Zn alloy plating layer, 5% Al-Zn alloy plating layer, Al-Mg-Zn alloy plating layer, and a Ni-Zn alloy plating layer.
[0021]
　Plating layer 2 may include antimony. In the plating layer 2 containing an antimony, as compared with the case where an antimony-free, corrosion resistance of the surface treated steel sheet 10 tends to be low. In the present embodiment, the plating layer 2 has also comprise antimony, by coating 3 formed on the plating layer 2, excellent dew whitening resistance, stack whitening resistance and corrosion resistance can be obtained.
　Coating weight of the plating layer 2 is not particularly limited, and may be in a conventional general range.
[0022]
1.3 coating
　film 3 is formed on the plating layer 2.
　Film 3, as shown in FIG. 1, a first component 31 comprising a resin particle composed of an average particle diameter of 20 ~ 200 nm of the polyurethane resin (resin component), and a second component 32 which, except for the first component 31. The area ratio of the first component 31 in the cross section of the film 3 is 35 to 80%. The second component 32 includes a phosphorus (P) and titanium (Ti) and vanadium (V) and silicon (Si). During film 3 P is contained 2.5-7.5 wt% phosphoric acid conversion. During film 3, the first component 31 and second component 32 are substantially uniformly dispersed.
[0023]
　Film 3, the aqueous surface-treating agent including each component included in the coating 3 at a predetermined ratio, was coated on the plating layer 2 is obtained by drying. The following describes the mechanism of film 3 of this embodiment is formed.
[0024]
　When the aqueous surface-treating agent including each component included in the coating 3 at a predetermined ratio is coated on the plating layer 2, phosphorus aqueous surface-treatment in the drug (P) is deposited on the surface of the plating layer 2, the first component 31 (resin component) self-aligned manner substantially uniformly dispersed coating film is formed. This is a water-based surface treatment agent, and the balance of the surface energy of the plating layer 2 with phosphorus deposited in the aqueous surface treatment agent
, and is a proper balance between the specific gravity of the first component 31 present in the aqueous surface-treatment in drug It is presumed to be due to some. When drying the coating film obtained by applying the aqueous surface-treating agent, while maintaining a substantially uniform dispersion state of the first component 31 in the coating film, the first component 31 and the adjacent first component 31 to , film 3 in which the second component 32 is substantially uniformly arranged which exist between the 31 is presumed to be formed.
[0025]
　Incidentally, the water-based surface treatment agent in the present embodiment as described later, contains acetic acid component. Acetate component can stabilize the pH of the aqueous surface-treating agent by pH buffering action. Precursor of silicon (Si) in the aqueous surface-treatment in the drug, for example, to stabilize by suppressing condensation reaction of the silane coupling agent, as a result, it contributes to the suppression of aggregation and association of resin particles of the first component It is considered to have. By thus acetate component stabilizes the components in the aqueous surface-treating agent, even in the film 3 to be formed and it is possible to first component 31 is present as a relatively uniform and fine resin particles. In contrast, if the aqueous surface-treating agent does not contain acetic acid component, each component of such the aqueous surface-treating agent is not stable, the first component in the coating to be formed as a result are dispersed uniformly and fine it can not be.
[0026]
　In the film 3 first component 31 and second component 32 are substantially uniformly distributed, corrosion resistance of the first component 31 and second component 32, the effect of improving the resistance to condensation whitening resistance and stack whitening resistance in coating the entire surface substantially it is uniformly obtained. As a result, the surface treated steel sheet 10 of the present embodiment, excellent corrosion resistance and condensation whitening resistance and stack whitening resistance. Such expression principle effect is not clear, but illustrating the expression mechanism of effects expected below.
[0027]
　That is, first, the film forming effect of the silicon contained in the first component 31 and second component 32, the film 3 is uniformly formed, exhibits adhesiveness and excellent barrier properties. Therefore, in any location of the film 3, it is possible to suppress the penetration of water, oxygen and the like, each component of the surface treated steel sheet 10 from the film 3 is suppressed to be leached to the surface of the film 3 . As a result, as well as improved corrosion resistance film 3, resistance to dew whitening resistance and stack whitening resistance is improved.
[0028]
　On the other hand, titanium (Ti) and vanadium (V), since it is substantially uniformly distributed in the coating 3 the entire surface, even if corrosion in part of the surface treated steel sheet 10 is started, these components can access quickly that portion, you are possible to suppress the corrosion. Additionally, titanium (Ti) and vanadium (V), since it is substantially uniformly distributed in the coating 3 the entire surface, there in case of titanium in a part of the surface treated steel sheet 10 (Ti) and vanadium (V) is insufficient even, titanium (Ti) and vanadium (V) is supplied to the fast that portion.
[0029]
　Then, a film-forming effect of the silicon (Si) contained in the first component 31 and second component 32, the synergistic effect of the corrosion inhibition effect of titanium (Ti) and vanadium (V), excellent corrosion resistance, resistance condensation whitening resistance and stack whitening resistance.
[0030]
　In this embodiment, the dispersed state of the first component 31 in the film 3 is evaluated using the maximum value of the distance between the centers of gravity of the resin particles. In the present embodiment, the maximum value of the distance between the centers of gravity of the resin particles is not more than 3.0 times the average particle size, more preferably 2.5 times or less, further preferably 2.0 times or less. If the maximum value of the distance between the centers of gravity of the resin particles is 3.0 times or less, the effect of the first component 31 and second component 32 are uniformly arranged in the film 3 becomes higher, corrosion resistance, condensation whitening resistance and an excellent surface-treated steel sheet 10 to the resistance stack whitening resistance. On the other hand, in order to achieve both barrier properties and adhesion of the first component 31 improvement and the corrosion resistance improving effect by the second component 32 as a sufficiently excellent ones, the maximum value of the distance between the centers of gravity of the resin particles is preferably 1.0-fold of the average particle size, more preferably 1.25 times or more, further preferably 1.5 times or more.
[0031]
　The maximum value of the distance between the centers of gravity of the resin particles in the film 3 can be obtained as follows.
　First, cross-sectional TEM-EDX (Transmission Electron Microscope - Energy dispersive X-ray spectrometry) carbon element mapping or high-angle scattering annular dark-field (STEM-HAADF, High-angle Annular Dark Field Scanning TEM) of any of the coating 3 by image No. in three of the cross-section of the first component 31, to identify the resin particles, the outline is the outermost of the same resin particle. For nearly perfect circle resin particles to be measured, the particle diameter and the center of gravity of the resin particles, and the particle size, the center of gravity itself. Further, when the resin particles to be measured is not a perfect circle, the maximum diameter of the resin particles, and measuring the minimum diameter, it considered the section of the resin particles each major axis, and an ellipse to the minor axis. And then, after calculating the area of the ellipse, as a true circle of the area having the center of gravity of the maximum and minimum diameters intersect, to determine the resin particle diameter, the center of gravity.
[0032]
　Then, in three of the cross-section of the first component 31 in the cross section of the film 3, the center of the case adjacent, and the distance between the centers of gravity of the contact and non resin particles (the cross-sectional shape of each of the resin particles was considered circular with each other to each other calculates the maximum value between a distance), the average value of the values obtained from the three cross sections, the maximum value of the distance between the centers of gravity of the resin particles.
　Incidentally, the specific gravity of the resin particles is regarded as constant, it is possible to calculate such as the center of gravity.
[0033]
　2 and 3 are schematic cross-sectional view of a film for explaining a method of comparing the average particle size of the inter-centroid distance and the resin particles. In FIG. 2, an example maximum value of the distance between the centers of gravity is less than 3.0 times the average particle diameter of the resin particles, in FIG. 3, the maximum value of the distance between the centers of gravity of the resin particles is an average particle size of examples are 3.0 times greater, respectively shown. Note that the plating layer and steel sheet 1 was omitted.
　In FIG. 2, first, adjacent to each other in the film 3, and obtains the distance between the centers of gravity l of resin particles 311 each other not in contact with each other. Then, as compared with an average particle size of the resin particles 311, obtains the ratio of the average particle size of the maximum value of the distance between centroids l of the resin particles 311. Incidentally, it showed a virtual resin particles 312 having an average particle size by a broken line.
[0034]
　In FIG. 3, first, adjacent to each other in the film 3A, and obtains the distance between the centers of gravity lA resin particles 311A ​​to each other not in contact with each other. Then, as compared with an average particle size of the resin particles 311A, obtains the ratio of the average particle size of the maximum value of the distance between centroids lA resin particles 311A. Incidentally, it showed a virtual resin particles 312A having an average particle size by a broken line.
[0035]
　Also, smoothness of the surface 33 of the film 3 has a correlation with the dispersion state of the resin particles 31 in the coating 3. Therefore, even using the surface roughness of the film 3 (Ra), to assess the state of dispersion of the resin particles in the coating 3. Moreover, the dispersion state of the resin particles in the film 3, the surface roughness of the film 3 with (Ra), or in place of the surface roughness of the film 3 (Ra), maximum cross-sectional height of the roughness curve (Rt) and / or root mean square roughness (Rq) may be assessed using the.
[0036]
　Surface roughness of the film 3 (Ra) (hereinafter, also referred to as "Ra-F".) Is preferably 1 ~ 10 nm. When the surface roughness of the film 3 (Ra-F) is at 1nm or more, it can be easily produced and excellent productivity. When the surface roughness of the film 3 (Ra-F) is at 10nm or less, effect of the first component 31 and second component 32 are uniformly arranged in the film is made more higher, more corrosion resistance, an excellent surface treated steel sheet 10 to withstand condensation whitening resistance and stack whitening resistance. Surface roughness of the film 3 (Ra-F) is preferably 5nm or less.
[0037]
　The same reason as preferable surface roughness of the film 3 (Ra-F) is at 1 ~ 10 nm, preferably maximum section height of the roughness curve of the film 3 (Rt) is 20 ~ 200 nm, root mean square roughness of the film 3 (Rq) is more preferably 1 ~ 10 nm. Note that scans an arbitrary rectangular region of the four sides 1μm using an atomic force microscope, and calculates the arithmetic mean roughness from the measured data (Ra), the maximum section height (Rt) Root Mean Square Roughness (Rq) be able to.
[0038]
　The area ratio of the first component 31 (resin component) in the cross section of the film 3 is 35 to 80%. In the present embodiment, the area ratio of the first component 31 of the film 3, since 35% or more, the film forming function of the first component 31 is sufficiently obtained, and the film 3 which is excellent in barrier property and adhesion. Therefore, corrosion resistance, excellent surface treated steel sheet 10 to withstand condensation whitening resistance and stack whitening resistance. The area ratio of the first component 31, in order to further improve the barrier properties and adhesion improving effect of the first component 31 is preferably 40% or more. Further, in the present embodiment, since the area ratio of the first component 31 of the film 3 is 80% or less, the corrosion resistance improvement effect by the second component 32 is sufficiently obtained, resulting excellent corrosion resistance. The area ratio of the first component 31, in order to further improve the corrosion resistance improving effect by the second component 32 is preferably 60% or less.
[0039]
　The area ratio of the first component 31 (resin component) in the cross section of the film 3 can be obtained as follows.
　First, a carbon film is deposited as a protective film on the surface of the surface treated steel sheet 10, further using a FIB (focused ion beam processing apparatus), forming a carbon film of a few [mu] m. Then, the acceleration voltage 30kV using FIB (finishing; 5 kV) was carried out micro-sampling in which the a sample of the film 3 section is thinned. The obtained sample was observed using an EDS TEM with (energy dispersive X-ray spectrometer) (transmission electron microscopy) or SEM (scanning electron microscope), the film 3 of each surface treated steel sheet 10, 3 go EDS analysis of a cross section of the portion (the element mapping) to give C, P, Ti, V, each element map of Si. The resulting elemental map is divided into 100 squares (10 × 10), binarizes the C and other elements to calculate the area ratio of the resin component in the cross section of the coating.
[0040]
　The thickness of the coating 3 does not but is preferably 0.99 ~ 900 nm is not limited to this. If the thickness of the film 3 is 0.99 ~ 900 nm, the corrosion resistance improving effect by coating 3 becomes prominent, even better corrosion resistance can be obtained.
[0041]
　It will be described in detail with the first component 31 constituting the film 3 and the second component 32.
(I) a first component
　first component 31 comprises a resin particle composed of an average particle diameter of 20 ~ 200 nm of the polyurethane resin. Polyurethane resin, the balance of tensile strength and elongation to form a good film. Therefore, film 3 comprising a first component 31 comprising a polyurethane resin is excellent in barrier property and adhesion. Therefore, the surface treated steel sheet 10 of the present embodiment has excellent corrosion resistance, resistance to dew whitening resistance and stack whitening resistance.
[0042]
　The content of the polyurethane resin in the coating 3 is preferably 25 to 45 mass%. The content of the polyurethane resin is 25 mass% or more, and more preferably is 30 wt% or more, barrier properties and arrive improving effect by the polyurethane resin, a coating 3 obtained more effectively. Less than 45% by weight content of the polyurethane resin, and more preferably is 40 wt% or less, since the content of the other components can be sufficiently ensured, better corrosion resistance is obtained.
[0043]
　When the average particle diameter of the polyurethane resin is less than 20 nm, the resin particles of polyurethane resin tends to agglomerate, the resin particles are hardly uniformly dispersed in the coating 3. As a result, there is a possibility that next film 3 in which the resin particles are arranged unevenly, corrosion resistance of the surface treated steel sheet 10, resistance to dew whitening resistance and stack whitening resistance is insufficient. In the present embodiment, the average particle size of the polyurethane resin is 20nm or more, excellent corrosion resistance and condensation whitening resistance and stack whitening resistance. When the average particle diameter of the polyurethane resin is 50nm or more, more excellent corrosion resistance and condensation whitening resistance and stack whitening resistance. Further, in the present embodiment, the average particle diameter of the polyurethane resin because it is 200nm or less, by forming the film 3 by the method described below, the film 3 in which the resin particles are substantially uniformly distributed are formed. The average particle diameter of the polyurethane resin is more preferably 100nm or less.
[0044]
　The average particle size of the resin particles of polyurethane resin in the coating can be calculated by a method of observing the coating section below. First, depositing a carbon film as a protective film on the surface of the steel sheet. Then, FIB (focused ion beam processing apparatus, SMI3050SE: Hitachi High-Tech Science Co., Ltd.) is used to deposit a carbon film of a few [mu] m. Then, the acceleration voltage 30kV using FIB (finishing; 5 kV) was carried out micro-sampling in which the a sample of the film cross-section is thinned. The resulting sample is observed using a TEM (transmission electron microscopy) or SEM (scanning electron microscope). It observed a large resin particles of circle equivalent diameters of resin particles selected 10 pieces, and the average value as the average particle size of the resin particles made of polyurethane resin.
　The present inventors have examined, the results of the average particle size of the resin particles made of a polyurethane resin which is calculated by the above method, in the present embodiment, an average particle diameter of the polyurethane resin used as a material for water-based surface treatment agent almost it was confirmed to match. Therefore, the average particle size of the resin particles of polyurethane resin in the coating can be regarded as the same as the average particle size of the polyurethane resin used as the material of the aqueous surface-treating agent.
[0045]
　The first component 31 (resin component), not only a polyurethane resin particles may include olefin wax and / or a phenolic resin.
　Olefin wax is contained as necessary, it may not be included. Olefin wax, in order to impart lubricity to the film 3, it is preferably contained in the resin component. The olefin wax, such as polyethylene wax, polyethylene wax oxide, and polypropylene oxide wax. Olefin wax is preferably a resin particle having an average particle diameter of 20 ~ 200 nm.
[0046]
　When the first component 31 comprises an olefin-based wax, the content of the olefin wax in the coating 3 is preferably 3.5 to 6.0 wt%. The content of the olefin wax is 3.5% by mass or more, more preferably If it is 4.0% by mass or more, next film 3 lubricity improving effect by olefin wax can be sufficiently obtained, excellent processability the surface-treated steel sheet 10. 6.0 wt% content of the olefin wax less, and more preferably is 5.5 wt% or less, since the content of the other components can be sufficiently ensured, better corrosion resistance is obtained.
[0047]
　The first component 31 may contain a phenol resin as necessary. When a phenol resin is contained in the film 3, the adhesiveness of the film 3 can be further improved.
[0048]
(Ii) a second component
　second component 32 includes a P and Ti and V and Si.
　Phosphorus contained in the second component 32 (P) is to prevent the zinc as a white rust caused in film 3 is eluted from the plating layer 2 suppresses the occurrence of white rust.
[0049]
　P content in the film 3 is 2.5 to 7.5 wt% phosphoric acid conversion. P content in the film 3 film 3 is 2.5 wt% or more phosphoric acid translation are formed sufficiently using an aqueous surface treatment agent containing phosphorus. Therefore, at the stage of the aqueous surface-treating agent coated on the plating layer 2, phosphorus in aqueous surface-treating agent is deposited on the surface of the plating layer 2, the surface energy of the plating layer 2 becomes a proper, first component 31 self-aligned manner substantially uniformly dispersed coating film is formed. As a result, by drying the coating film, coating 3 the first component 31 and second component 32 are substantially uniformly arranged is formed. Further, in the present embodiment, since the P content in the film 3 is 2.5 wt% or more, good resistance stack whitening resistance and filament tape can be obtained. P content in the coating 3, thereby improving the resistance to stack whitening resistance and filament tape resistance, since the first component 31 and second component 32 is a film 3 which is more uniformly arranged, phosphate conversion it is preferably 3.0 mass% or more. 7.5 wt% P content in the 3 phosphate conversion coating less, preferably If it is 7.0 wt% or less, with good blackening is obtained, the content of the other ingredients sufficiently It can be ensured, better corrosion resistance is obtained.
[0050]
　Titanium (Ti) and vanadium (V) is a component having a corrosion inhibiting effect, to improve the corrosion resistance of the surface treated steel sheet 10. Ti and V, the corrosion environment is different to function as each corrosion inhibitor is effectively exhibited. Therefore, as a corrosion inhibitor, in that it contains two of Ti and V, by the synergistic effect of Ti and V can inhibit corrosion under various corrosive environments, better corrosion resistance is obtained.
[0051]
　Ti content in the coating 3 is preferably 1.7-2.4 mass%. Ti content of 1.7 mass% or more, and more preferably is 1.9 mass% or more, becomes film 3 corrosion resistance improving effect by containing Ti can be sufficiently obtained, superior in corrosion resistance surface treated steel sheet of 10. Ti content of 2.4 wt% or less, more preferable to be 2.3 wt% or less, since the content of the other components can be sufficiently ensured, better corrosion resistance is obtained.
[0052]
　V content in the coating 3 is preferably 0.70 to a 0.90 mass%. V content is 0.70 mass% or more, and more preferably is 0.75 mass% or more, becomes film 3 corrosion resistance improving effect by the vanadium can be sufficiently obtained, the surface treated steel sheet 10 having more excellent corrosion resistance. When V content is 0.90 mass% or less, since the content of the other components can be sufficiently ensured, better corrosion resistance is obtained.
[0053]
　It is preferred mass ratio between Ti and V in the film 3 (Ti / V) is 2.1 to 2.9. (Ti / V) is 2.1 or more, and more preferably is 2.2 or more, a surface treated steel sheet 10 having next film 3 corrosion resistance improving effect by the titanium can be sufficiently obtained, excellent processability. (Ti / V) is 2.9 or less, and more preferably is 2.8 or less, the corrosion resistance improving effect by the vanadium can be sufficiently obtained, superior corrosion resistance is obtained.
[0054]
　Silicon (Si) has a film-forming effect, by exerting a barrier and adhesion, corrosion resistance, improve anti condensation whitening resistance and stack whitening resistance.
　Si content in the film 3, SiO 2 is preferably 10 to 40 mass% in terms of. Si content in the film 3, SiO 2 in terms of 10 mass% or more, preferably film 3 is not less than 20 mass% is formed sufficiently using an aqueous surface treatment agent containing Si. Therefore, by drying by applying a water-based surface treatment agent, a film 3 having excellent barrier properties three-dimensional cross-linking is formed by a siloxane bond. As a result, it obtained either film 3 having more excellent corrosion resistance improvement effect. Si content in the film 3, SiO 2 40% by mass in terms of less, preferably If it is 30 mass% or less, since the content of the other components can be sufficiently ensured, better corrosion resistance is obtained.
[0055]
　The content of P in the coating 3, Ti, V, Si is a film 3 fluorescent X-ray analysis can be calculated by regarding the P in the coating 3, Ti, V, Si is present as an oxide. The present inventors have studied, P (phosphate equivalent) in the film was calculated by the above method, Ti, V, Si (SiO 2 each component equivalent), the mass ratio to the total solid content of the aqueous surface-treating agent (phosphoric acid, Ti, V, Si (SiO 2 may correspond with conversion)) was confirmed. Therefore, P in the coating 3 (phosphoric acid conversion), Ti, V, Si (SiO 2 content conversion) (% by mass), and shows the mass ratio to the total solid content of the aqueous surface-treating agent as a percentage it can be considered.
[0056]
　Film 3, may contain fluoride ions. Fluoride ions in the coating 3, for example, the aqueous surface-treating in a drug to be used in forming the film 3, from the component containing the fluoride ions contained as necessary. Component containing a fluoride ion may each component as a coating 3, which is used to water-solubilizing or solubilization in an aqueous surface treatment in the drug. The content of fluoride ions in the film 3 is not particularly limited, for example, 0.3 mg · m -2 is less than, the occurrence of condensation whitening due to the inclusion of fluoride ions can be prevented more reliably. More specifically, the content of fluoride ions is 0.3 mg · m -2 is less than, the fluoride ion content to elute condensation water becomes small. Therefore, fluoride ions on film 3 in the drying process of the condensed water be concentrated and precipitation, it remains in trace amounts that do not appear as a condensation whitening. Accordingly, deterioration of the appearance due to condensation whitening (white rust) can be prevented.

WE claims

Steel plate and a plated layer containing zinc formed on the surface of the steel sheet, and a film formed on the plating layer,
　wherein the coating consists of an average particle diameter of 20nm or 200nm or less of the polyurethane resin resin particles and a resin component containing, and a P and Ti and V and Si,
　P to the coating during comprises a phosphate conversion 2.5% by weight or more 7.5 wt% or less,
　of the resin component in the cross section of the coating area ratio is 80% or less than 35%,
　and the resin particles are dispersed in the coating in, and the maximum value of the distance between the centers of gravity of the resin particles, the average particle diameter of the resin particles 3.0 fold or less, surface-treated steel sheet.
[Requested item 2]
　The surface roughness of the film (Ra) is 1nm or more 10nm or less, surface-treated steel sheet according to claim 1.
[Requested item 3]
　The surface roughness of the steel sheet (Ra) is 0.1μm or more 2μm or less, surface-treated steel sheet according to claim 1 or 2.
[Requested item 4]
　Surface treated steel sheet according to any one of the plating layer comprises antimony, claims 1 to 3.
[Requested item 5]
　Wherein the resin component comprises an olefinic wax and / or a phenolic resin, a surface treated steel sheet according to any one of claims 1 to 4.
[Requested item 6]
　Wherein the Si in the coating SiO 2 40 wt% 10 wt% or more in terms of
　less, the Ti or 1.7 wt% 2.4 wt% or less,
　includes a V 0.70 wt% to 0.90 wt% or less,
　mass ratio between Ti and V (Ti / V) is 2.1 to 2.9 or less, surface-treated steel sheet according to any one of claims 1 to 5.