JP2022158349A - Galvanized steel sheet having surface treatment film and method for manufacturing the same - Google Patents

Abstract

To provide a galvanized steel sheet having a surface treatment film excellent in plane part corrosion resistance and lubricity while having excellent conductivity without including any pollution control substance, such as hexavalent chrome and excellent in worked part corrosion resistance, skid resistance during lamination and coil crush resistance.SOLUTION: A galvanized steel sheet includes a surface treatment film on a galvanized layer. The surface treatment film includes: an elastomer component (a) including butadiene rubber in at least a part of particles having an average particle size of 20-500 nm; a wax component (b) having a flat shape; a silicon compound (c); a phosphorus compound (d); a vanadium compound (e); and a titanium compound (f). The area ratio of a region where the wax component (b) exists on the surface of the surface treatment film is 2-40%, and the area ratio of the elastomer component (a) in a region where the wax component (b) does not exist is 5-50%.SELECTED DRAWING: Figure 4

Description

The present invention is used in automobiles, home appliances, building materials, etc., and is an environmentally friendly zinc that has undergone a surface treatment that does not contain any pollution control substances such as hexavalent chromium in the surface treatment film formed on the surface of a zinc-based plated steel sheet. In particular, it is suitable for applications where it is necessary to prevent electromagnetic leakage (EMI), such as electrical and electronic equipment, and has excellent electromagnetic shielding properties. The present invention relates to a zinc-based plated steel sheet with a surface treatment film, which is excellent in durability, resistance to side slipping during lamination, and resistance to coil crushing.

In recent years, with the progress of digitization of home electric appliances and the speeding up of CPUs, etc., the problem of electromagnetic interference, which adversely affects peripheral devices and the human body, is being emphasized. In response to such problems, the "Voluntary Control Council for Interference by Information Processing Equipment (VCCI)" was established in Japan, and in recent years there has been an increasing trend toward self-regulation of electromagnetic interference problems in the industry in order to comply with VCCI standards. is getting stronger. As a countermeasure against electromagnetic noise generated from an electronic board or the like in an electric/electronic device, one example is a technique of enclosing the electronic board or the like with a shield box made of a metal (conductor) material to shield the electromagnetic wave.

The shield box shields electromagnetic waves by reflecting the electromagnetic waves with a conductive material forming the shield box. In addition, the higher the conductivity of the material forming the shield box, the higher the reflectance of electromagnetic waves, and the better the electromagnetic wave shielding performance. Therefore, in order to secure the electromagnetic wave shielding property of the shield box, it is important that the metal plate forming the shield box has high conductivity.

In addition, since the shield box is manufactured by molding a metal plate, it has discontinuous portions (seams and joints), and electromagnetic waves are likely to leak or enter through the discontinuous portions. Therefore, in a shield box, a gasket with good conductivity is usually inserted in the discontinuous portion to prevent leakage and intrusion of electromagnetic waves.

Here, in order to ensure the shielding performance of the shield box, it is necessary to have a structure that allows a desired current to pass through the entire shield box. However, since the contact pressure between the metal body and the gasket is usually low, the electrical conductivity (hereinafter simply referred to as "conductivity") between the metal body and the gasket is poor, and the amount of current flowing through the contact portion is low. tend to become Therefore, in addition to ensuring the electrical conductivity of the metal plate that constitutes the shield box, it is important to ensure the electrical conductivity between the metal plate and the gasket in order to further improve the performance of the shield box.

On the other hand, in light of the fact that electrical and electronic devices are used in all kinds of environments today, the materials that make up the shield box must not corrode even in harsh operating environments. is also required. For this reason, zinc-based plated steel sheets that have undergone chromate treatment with a treatment solution containing chromic acid, dichromic acid, or salts thereof as a main component have been widely used as materials for shield boxes.

As described above, the metal body (zinc-based plated steel sheet) forming the shield box is required to have high electrical conductivity, particularly electrical conductivity with the gasket. Here, the film formed on the surface of the zinc-based plated steel sheet by chromate treatment is inferior in conductivity to the base steel sheet, but even if it is a thin film, it is possible to exhibit rust prevention performance. Therefore, in the galvanized steel sheet subjected to chromate treatment, electrical conductivity comparable to that of the galvanized steel sheet (without surface treatment) can be obtained by making the film having poor electrical conductivity as thin as possible. That is, since the conductivity with the gasket is sufficiently ensured, it was possible to achieve both antirust performance and electromagnetic wave shielding performance. However, due to recent global environmental problems, there is an increasing demand for adopting a zinc-based plated steel sheet with a pollution-free surface treatment film that does not require chromate treatment, that is, a so-called chromium-free treated steel sheet.

Moreover, in many cases, the metal body (zinc-based plated steel sheet) that constitutes the shield box is turned into a product after undergoing some processing such as bending, press forming, roll forming, and the like. As a result, galling may occur during processing, resulting in damage and falling off of the metal surface, and cracks may occur in the base material due to insufficient lubricity in more severe processing. In order to solve these problems, it is necessary to have excellent lubricity.

Many technologies related to chromium-free treated steel sheets have already been proposed. For example, Patent Document 1 discloses a zirconium compound, a tetraalkoxysilane, a compound having an epoxy group, a chelating agent, a vanadic acid compound, and a specific metal compound. in a specific ratio, and a second layer surface treatment liquid containing an organic resin and a lubricant to form a two-layer film.

Patent Document 2 discloses a surface treatment containing a specific resin emulsion, a tetraalkoxysilane, a specific silane coupling agent, a chelating agent, a vanadate compound, a titanium compound, and a lubricant in a specific ratio. Techniques for forming a film using a liquid have been disclosed.

In Patent Document 3, after forming a base film containing Zr and F using a treatment agent containing hexafluorozirconic acid and an inorganic acid, a specific urethane rubber, a carbodiimide resin, and an organic titanium compound are applied thereon. and a technique of forming an upper layer film using a treatment agent containing colloidal silica and polyethylene wax in a specific ratio.

In Patent Document 4, a surface treatment liquid having a specific pH and a specific free acidity and containing a specific metal ion, phosphoric acid, an organic resin, a solid lubricant, and a specific additive is used. A technique for forming a coating on the surface is disclosed.

In Patent Document 5, an acidic inorganic coating agent containing a zirconium compound, water-dispersible silica, a magnesium compound, a vanadium compound and a fluorine compound, a urethane resin, a silicate, a titanium compound, and a polycarbodiimide resin are coated on a zinc-based plated steel sheet. and an alkaline organic-inorganic composite coating containing a silane coupling agent to form a two-layer coating.

Coatings formed by these techniques achieve both corrosion resistance and electrical conductivity in a thin film by adding organic or inorganic components in combination. Further, by adding a lubricant such as wax to the film, lubricity is enhanced, and in addition to corrosion resistance and electrical conductivity, it is aimed at obtaining a film excellent in lubricity.

Japanese Patent No. 5754102 JP 2012-092443 A Japanese Unexamined Patent Application Publication No. 2011-017082 JP 2007-284710 A WO2013/161621A1

Steel sheets to which lubricity has been imparted according to the above-described conventional techniques are often shipped in the form of coils because the steel sheets are extremely long when manufactured by steel manufacturers. In that case, the problem is that the coil is crushed or the winding becomes loose. In addition, when the steel sheet is used for applications such as automobiles, home appliances, and building materials, it is difficult to process the steel sheet directly from the coil. . In that case, the cut steel sheets are stacked and stored, but in that case, the problem is that the stacked body tends to slide sideways. In either case, the problem of handling after production remains. Therefore, there is a demand for a galvanized steel sheet with a surface treatment film, which is excellent in lubricity and less likely to cause problems such as side slippage and coil crushing during lamination.

Furthermore, as mentioned above, the metal body (zinc-based plated steel sheet) that makes up the shield box is often subjected to some kind of processing during use. Corrosion resistance of processed parts is now required. Therefore, there is a demand for a zinc-based plated steel sheet with a surface treatment film that is excellent in corrosion resistance of processed parts in addition to general corrosion resistance of flat parts.

The present invention solves the above-mentioned problems that have not been solved by the prior art. It is an object of the present invention to provide a zinc-based plated steel sheet with a surface treatment film, which is excellent in corrosion resistance of worked parts, resistance to sideslip during lamination, and resistance to coil crushing, together with its production method.

The present inventors have made intensive studies to solve the above problems. It was found that a film having relatively excellent electrical conductivity and flat surface corrosion resistance can be obtained.

In addition, the present inventors have found that by realizing a state in which an elastomer component containing butadiene rubber is dispersed as fine particles in a film made of inorganic components (silicon compound, phosphorus compound, vanadium compound, titanium compound), corrosion resistance, especially processing, can be improved. We paid attention to the possibility of improving the corrosion resistance of the parts. The present inventors have found that, for the first time in the above composition system, an inorganic component (silicon compound, It was confirmed that a film in which the elastomer component containing butadiene rubber is dispersed as fine particles can be obtained in the film of phosphorus compound, vanadium compound, titanium compound). They have also found that when the area ratio of the elastomer component containing the butadiene rubber is within a specific range, the corrosion resistance of the processed parts is greatly improved, and the corrosion resistance of the flat parts is also improved. rice field. In other words, the inventors have found a method that achieves a high level of both conductivity, corrosion resistance of flat portions, and corrosion resistance of processed portions.

Furthermore, the inventors have also found that by adding a wax component to the coating described above and allowing the coating to exist as flat particles occupying a specific area ratio, it is possible to achieve both lubricity, side-slip resistance during lamination, and coil crush resistance.
Based on the above knowledge, zinc with a surface treatment film that satisfies all of the corrosion resistance of flat parts, corrosion resistance of processed parts, lubricity, side slip resistance during lamination, and coil collapse resistance while having good conductivity. We succeeded in obtaining a system plated steel sheet.
That is, the gist of the present invention is as follows.

1. A zinc-based plated steel sheet having a surface treatment film on a zinc-based plating layer, the surface treatment film comprising:
an elastomer component (a) containing butadiene rubber as at least a portion of particles having an average particle size of 20 nm to 500 nm;
a wax component (b) having a flattened shape;
a silicon compound (c);
a phosphorus compound (d);
a vanadium compound (e);
a titanium compound (f);
including
The area ratio of the region where the wax component (b) exists on the surface of the surface treatment film is 2% to 40%, and the area of the elastomer component (a) in the region where the wax component (b) does not exist. A zinc-based plated steel sheet with a surface treatment film, wherein the ratio is 5% to 50%.

2. In the surface treatment film, the silicon compound (c) is 20.0% by mass to 50.0% by mass in terms of SiO ₂ , and the phosphorus compound (d) is 0.4% by mass to 8.0% by mass in terms of P. %, 0.1% by mass to 2.0% by mass of the vanadium compound (e) in terms of V, and 0.1% by mass to 2.0% by mass of the titanium compound (f) in terms of Ti, 2. The zinc-based plated steel sheet with the surface treatment film according to 1.

3. 3. The zinc-based plated steel sheet with a surface treatment film according to 1 or 2 above, wherein the valence of vanadium in the vanadium compound (e) is tetravalent.

4. 4. The surface according to any one of 1 to 3 above, wherein the elastomer component (a) exists in an area ratio of 5% or more in a square region of 1 μm×1 μm extracted from the region where the wax component (b) does not exist. Galvanized steel sheet with treatment film.

5. 5. The zinc-based plated steel sheet with a surface treatment film according to any one of 1 to 4 above, wherein the area ratio of the region where the wax component (b) is present in the surface treatment film is less than 1%. .

6. 6. The galvanized steel sheet with a surface treatment film according to any one of 1 to 5, wherein the elastomer component (a) further contains urethane rubber or polyurethane thermoplastic elastomer.

7. An elastomer emulsion (A) containing butadiene rubber as at least part of particles having an average particle size of 20 nm to 500 nm, a wax (B), and a silane compound (C) are applied to the surface of the zinc-based plating layer of a zinc-based plated steel sheet. , a phosphonic acid compound (D), a vanadium compound (E), a titanium compound (F), and water under the conditions of [I] and [II] below, and having a pH of 3.0 to 7 .0 surface treatment liquid is applied, and then heat-dried under conditions in which the temperature reached by the steel sheet is 10°C or more higher than the melting point of the wax (B) to form a surface treatment film, A method for producing a zinc-based plated steel sheet with a surface treatment film.
[I] The ratio (A _S )/(NV) of the mass (A _S ) of the solid content of the elastomer emulsion (A) containing the butadiene rubber to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0. .05 to 0.45
[II] The ratio (B _S )/(NV) of the solid content (B _S ) of the wax (B) to the total solid content (NV) of the aqueous surface treatment liquid is 0.003 to 0.050.

8. 8. The method for producing a zinc-based plated steel sheet with a surface treatment film according to 7 above, wherein the surface treatment liquid satisfies the following conditions [III] to [VI].
[III] The ratio (C _SiO2 )/(NV) of the mass (C _SiO2 ) of the silane compound (C) in terms of SiO ₂ to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.20. ~0.50
[IV] The ratio (D _P )/(NV) of the P-converted mass (D _P ) of the phosphonic acid compound (D) to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.004 to 0.080
[V] The ratio (E _V )/(NV) of the V-equivalent mass (E _V ) of the vanadium compound (E) to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.001 to 0. .020
[VI] The ratio (F _Ti )/(NV) of the Ti-equivalent mass (F _Ti ) of the titanium compound (F) to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.001 to 0. .020

9. 9. The method for producing a zinc-based plated steel sheet with a surface treatment film according to 7 or 8 above, wherein the vanadium compound (E) is a vanadyl compound.

10. 10. The method for producing a zinc-based plated steel sheet with a surface treatment film according to any one of 7 to 9 above, wherein the elastomer emulsion (A) further contains a urethane rubber or a thermoplastic polyurethane elastomer.

11. At least one silane coupling, wherein the silane compound (C) has a tetraalkoxysilane and/or at least one reactive functional group selected from active hydrogen-containing amino groups, epoxy groups, mercapto groups and methacryloxy groups. 11. The method for producing a zinc-based plated steel sheet with a surface treatment film according to any one of 7 to 10 above, wherein the surface treatment film is a coating agent.

According to the present invention, it is possible to provide a galvanized steel sheet with a surface treatment film, which is excellent in various performances such as conductivity, corrosion resistance, and lubricity, and is also excellent in resistance to sideslip during lamination and resistance to coil crushing.

It is a schematic front view showing a dynamic friction coefficient measuring device. It is a schematic perspective view showing the shape and dimensions of the beads used. It is a schematic front view showing a static friction coefficient measuring device at the beginning of slipping. No. 14 (invention example) surface SEM image in the range of 20 μm × 20 μm. No. 14 (invention example) surface SEM image in the range of 2 μm × 2 μm. No. 28 (comparative example) is a surface SEM image of an area of 20 μm×20 μm. No. 26 (comparative example) is a surface SEM image of a 2 μm×2 μm area.

Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In the present specification and drawings, constituent elements having substantially the same functional configuration are denoted by the same reference numerals, thereby omitting redundant description. Further, in this specification, the description of a numerical range such as "a to b" is intended to include not only the range between a and b, but also the upper and lower limits. That is, in this specification, for example, the description "a to b" means "a or more and b or less".

1. Zinc-based plated steel sheet with surface treatment film 1.1 Steel sheet The zinc-based steel sheet used in the present invention is not particularly limited as long as it has a zinc-based plating layer. The zinc-based plated steel sheet includes hot-dip galvanized steel sheet (GI) or alloyed hot-dip galvanized steel sheet (GA), hot-dip Zn-5% by mass Al alloy-plated steel sheet (GF), and hot-dip Zn-55 Examples include mass % Al alloy plated steel sheet (GL), electrogalvanized steel sheet (EG), and electrozinc-Ni alloy plated steel sheet (Zn-11 mass % Ni).

1.2 Surface Treatment Film In the present invention, a surface treatment film is formed on the zinc-based plated steel sheet. The surface treatment film of the present invention comprises particles having an average diameter of 20 nm to 500 nm, an elastomer component (a) containing butadiene rubber in at least a part of the particles, and a wax component (b) having a flat structure. ), a silicon compound (c), a phosphorus compound (d), a vanadium compound (e), and a titanium compound (f). The term “elastomer” as used herein refers to polymeric substances that exhibit rubber elasticity at room temperature, and includes thermosetting elastomers (butadiene rubber, isoprene rubber, polyurethane rubber, butyl rubber, etc.) and thermoplastic elastomers (polyurethane-based thermal elastomers). plastic elastomers, acrylic thermoplastic elastomers, etc.).

The area ratio of the region where the wax component (b) exists on the surface of the surface treatment film of the present invention is 2% to 40%. Further, the area ratio of the region where the elastomer component (a) exists in the region where the wax component (b) does not exist on the surface of the surface treatment film of the present invention is 5% to 50%, and the elastomer component ( a) is dispersed as particles.

In the film of the present invention, the silicon compound (c) is 20.0% by mass to 50.0% by mass in terms of SiO ₂ , and the phosphorus compound (d) is 0.4% by mass to 8.0% in terms of P. % by mass, the vanadium compound (e) is 0.1% by mass to 2.0% by mass in terms of V, and the titanium compound (f) is 0.1% by mass to 2.0% by mass in terms of Ti. preferable.

The surface treatment film of the present invention is obtained by applying an aqueous surface treatment solution containing each component contained in the film in a predetermined ratio onto a zinc-based plated steel sheet and drying it at a predetermined temperature. The mechanism by which the surface treatment film of the present invention is formed will be described below.

When the surface treatment liquid containing the above-described components in a predetermined ratio, which is contained in the surface treatment film of the present invention, is applied to a zinc-based plated steel sheet and dried at a predetermined temperature, the silicon compound (c) is the main component The phosphorus compound (d), the vanadium compound (e), and the titanium compound (f) are dispersed in the film, and the elastomer component (a) is dispersed as particles. Further, the wax component (b) is present as flat particles on the surface of the inorganic coating.

In order to realize the film structure described above, the surface energy of each component in the surface treatment solution should be properly balanced so that the elastomer component (a) can be easily dispersed in the film mainly composed of the silicon compound (c). Also, it is important to raise the temperature to a temperature higher than the melting point of the wax to promote melting of the wax and bonding between the waxes.

As will be described later, the surface treatment liquid in the present embodiment comprises an elastomer emulsion (A) containing butadiene rubber and a silane compound ( C) and a phosphonic acid compound (D) as a precursor of the phosphorus compound (d). It is presumed that the film-forming action of the elastomer emulsion (A) containing the silane compound (C) and butadiene rubber forms a structure in which the elastomer component is dispersed in the silicon compound (c). In addition, the phosphonic acid compound (D) is thought to act as an emulsifier to suppress aggregation and association between the butadiene rubber-containing elastomer emulsions (A). It is presumed that (a) can realize a structure in which fine particles are dispersed in the film. On the other hand, when the surface treatment liquid does not contain the silane compound (C) or does not contain the phosphonic acid compound (D), the elastomer component (a) is contained in the film mainly composed of the silicon compound (c). A structure dispersed as fine particles cannot be realized.

In the surface treatment film of the present invention, by including an elastomer component (a) containing butadiene rubber, a silicon compound (c), a phosphorus compound (d), a vanadium compound (e), and a titanium compound (f), Even with a thin film, excellent flat surface corrosion resistance can be achieved, and both excellent conductivity and flat surface corrosion resistance can be achieved. A structure in which the phosphorus compound (d), the vanadium compound (e), and the titanium compound (f) are dispersed in the film mainly composed of the silicon compound (c), and the elastomer component (a) is dispersed as particles. As a result, the corrosion resistance of the processed portion is improved, and it is possible to achieve a high level of both conductivity, corrosion resistance of the flat portion, and corrosion resistance of the processed portion. Furthermore, by allowing the flat-shaped wax component (b) to exist in the form of particles on the film surface in a specific area ratio, it is possible to achieve both lubricity during processing and anti-skidding properties during lamination. Although the principle of manifestation of such an effect is not clear, the presumed mechanism of manifestation of the effect will be described below.

[Flat part corrosion resistance]
First, by adding the elastomer component (a) containing butadiene rubber to the film mainly composed of the silicon compound (c), the film becomes more dense than when the silicon compound (c) is used alone. It is considered that the barrier property of the surface area is improved, and the corrosion resistance of the flat surface is improved. In addition, by including the phosphorus compound (d), vanadium compound (e), and titanium compound (f), even when part of the steel plate begins to corrode, the above components quickly elute and form a protective film. Therefore, progress of corrosion can be suppressed. A protective film formed by combining these phosphorus compound (d), vanadium compound (e), and titanium compound (f) has higher barrier properties than when these compounds exist alone. It is presumed that excellent flat corrosion resistance can also be realized. Therefore, even a thin film can achieve excellent planar corrosion resistance, and both conductivity and planar corrosion resistance can be achieved.

[Corrosion resistance of processed parts]
Furthermore, as found in the present invention, the film mainly composed of the silicon compound (c) contains the phosphorus compound (d), the vanadium compound (e), and the titanium compound (f) dispersed therein, and further contains butadiene rubber. The structure in which the elastomer component (a) is dispersed as particles makes it possible to obtain a coating excellent in corrosion resistance of processed parts. The reason for this is that the elastomer component (a) containing butadiene rubber is dispersed in the film mainly composed of the silicon compound (c), so that the elastomer component (a) containing butadiene rubber disperses the stress during processing. It is presumed that the same barrier effect is maintained in the processed part as in the flat part in order to suppress the damage of the film. In addition, since the phosphorus compound (d), the vanadium compound (e), and the titanium compound (f) are dispersed, even when the film is damaged and the barrier property is lost, the above components are quickly eluted, It is thought that there is also an effect of forming a protective film and suppressing the progress of corrosion.

[Lubricity]
In addition, in the surface treatment film of the present invention, by allowing the wax component (b) to exist as flat particles in a specific area ratio, lubricity can be ensured first. That is, for example, when a steel plate is subjected to bending, press forming, roll forming, or other processing, if the film receives a high load, the wax component (b) will come into contact with the mating material (die or jig for processing). However, the coefficient of friction is reduced by the effect of the wax.

[Slip resistance (and coil crush resistance) during lamination]
Furthermore, in the surface treatment film of the present invention, by allowing the wax component (b) to exist in the form of flat particles in a specific area ratio, it is possible to achieve both excellent lubricity and skidding resistance during lamination. In the film of the present invention, the elastomer component (a) is dispersed in the film as fine particles, some of which protrude from the surface of the film. Therefore, since the wax component (b) exists as flat particles, the elastomer component (a) is preferentially used as a counterpart when a low load is applied to the coating, such as when steel sheets with coatings are laminated and used. It is presumed that slippage is suppressed because the wax component (b) is in contact with the material (steel sheet or film in the steel sheets being laminated, the same applies hereinafter) and the wax component (b) does not contact the counterpart material. It is presumed that due to such a mechanism, it is possible to suppress sideslip and coil crushing during lamination while maintaining high lubricity during processing. On the other hand, if the wax component (b) does not have a flat shape, the wax will come into contact with the mating material even when a low load is applied to the film, such as when steel sheets are laminated, and its lubricating effect will appear, resulting in anti-skid resistance during lamination. presumed to deteriorate.

In addition, for example, coil collapse, which is a problem when steel sheets are coiled and shipped, is caused by slipping between steel sheets. can be evaluated.

Here, that the wax component (b) is flat-shaped particles means that the average aspect ratio AR of the wax component particles is 10 or more. Non-flat particles may be included as long as the average aspect ratio AR is 10 or more. The average aspect ratio AR in the film is calculated as follows. First, particles on the film surface are observed using a scanning electron microscope (SEM), and the length L of the longest line segment that can be drawn within the outline of the particle is determined. This operation is performed on 10 wax particles randomly extracted from the film surface, and the arithmetic mean Lav is obtained. Next, the film is observed from the cross section using SEM, the maximum thickness tmax and the minimum thickness tmin of the particles are measured, and the average value (tmax+tmin/2) is calculated. This operation is performed on 10 wax particles randomly extracted from the film cross section, and the arithmetic mean tav is calculated. Lav/tav, which is Lav divided by tav, is the average aspect ratio AR.

Next, the structure of the surface treatment film of the present invention will be described in detail.
On the surface of the surface treatment film of the present invention, it is essential that the area ratio of the region where the wax component (b) exists is 2% to 40%. If the area ratio is less than 2%, the lubricity improvement effect of the wax (b) does not appear, resulting in insufficient lubricity. On the other hand, if the area ratio is more than 40%, the slipperiness is too high, and side slippage and coil crushing during lamination are likely to occur.

The area ratio of the region where the wax component (b) exists on the surface of the surface treatment film of the present invention is calculated as follows. First, the film surface is observed using a scanning electron microscope (SEM), and SEM images in a range of about 20 μm×20 μm are randomly photographed in five fields. At this time, in order to obtain information on the film surface, the observation is performed under the condition of an acceleration voltage of 1 kV or less. In the resulting SEM image of the film surface, the wax component (b) is observed as flattened particles having a darker contrast than the surroundings. Therefore, the photographed SEM image is binarized by image processing, and the area ratio of the flat particles is calculated. Then, this is carried out for all five extracted fields of view, and by taking the average, it is possible to calculate the area ratio of the region where the wax component (b) exists on the surface of the surface treatment film.

More desirably, the area ratio of the region where the wax component (b) exists inside the surface treatment film of the present invention is less than 1%. When the area ratio is less than 1%, the inside of the coating becomes denser, and superior corrosion resistance can be obtained. Here, the inside of the surface treatment film can be defined as an SEM image obtained when the surface treatment film is observed with an SEM at an acceleration voltage of 2 to 5 kV.

The area ratio of the region where the wax component (b) exists inside the surface treatment film of the present invention is calculated as follows. First, the film surface is observed using a scanning electron microscope (SEM), and SEM images in a range of about 20 μm×20 μm are randomly photographed in five fields. At this time, in order to obtain information on the inside of the film, an SEM image obtained when observed under conditions of an acceleration voltage of 2 kV or more and 5 kV or less is taken. In the obtained SEM image of the inside of the film, the wax component (b) is observed as flattened particles having a darker contrast than the surroundings. Therefore, the photographed SEM image is binarized by image processing, and the area ratio of the flat particles is calculated.

In addition, it is essential that the area ratio of the elastomer component (a) in the region where the wax component (b) does not exist on the surface of the surface treatment film of the present invention is 5% to 50%. When the area ratio is 5% to 50%, the corrosion resistance of the processed portion and the side slip resistance during lamination are sufficient. If the area ratio is less than 5%, the corrosion resistance of the worked portion deteriorates, and the sideslip resistance during lamination also becomes insufficient. On the other hand, if the area ratio is more than 50%, the corrosion resistance of the plane portion and the corrosion resistance of the processed portion will be insufficient.

The area ratio of the area where the elastomer component (a) exists in the region where the wax component (b) does not exist on the surface of the surface treatment film can be calculated, for example, by the following method. First, the film surface was observed using a scanning electron microscope (SEM), and 5 SEM images of a range of about 2 µm × 2 µm from the region where the wax component (b), which is a flat particle, does not exist, were randomly selected. Take a picture of the field of view. At this time, in order to obtain information on the film surface, the observation is performed under the condition of an acceleration voltage of 1 kV or less. In the resulting SEM image of the coating surface, the elastomer component (a) is observed as particles with darker contrast than the surroundings. Therefore, the photographed SEM image is binarized by image processing, and the area ratio of dark particles is calculated. Then, this is carried out in all five extracted fields of view, and the average is taken to calculate the "area ratio of the area where the elastomer component (a) exists in the region where the wax component does not exist on the surface of the surface treatment film". be able to.

Further, in the present invention, it is more preferable that the elastomer component (a) is more uniformly dispersed in the film. The state of dispersion of the elastomer component (a) can be evaluated using the "area ratio of the elastomer component (a) present in a 1 μm×1 μm square region extracted from a region where the wax component (b) does not exist". In the surface treatment film of the present invention, the area ratio of the elastomer component (a) in an arbitrary square region of 1 μm×1 μm extracted from the region where the wax component (b) does not exist is preferably 5% or more. More preferably, it is 8% or more. When the area ratio is 5% or more, the elastomer component (a) is dispersed more uniformly in the film mainly composed of a silicon compound. Further excellent corrosion resistance of processed parts can be obtained.

In order to confirm that the area ratio of the elastomer component in an arbitrary square region of 1 μm×1 μm extracted from the region where the wax component (b) does not exist on the surface of the surface treatment film is 5% or more, the following steps are performed. Various methods can be used.
First, a scanning electron microscope (SEM) is used to observe the coating surface, and 10 square areas of 1 μm×1 μm are randomly extracted from the area where the wax component (b), which is a flat particle, does not exist. At this time, in order to obtain information on the film surface, the observation is performed under the condition of an acceleration voltage of 1 kV or less. In the resulting SEM image of the film surface, the elastomer component (a) is observed with a darker contrast than the surroundings. Calculate the area ratio of (a). Then, this is carried out in all of the extracted 10 fields of view, and if it is confirmed that the area ratio is 5% or more in all of the 10 fields of view, the "arbitrary 1 μm × 1 µm area extracted from the region where the wax component (b) does not exist The area ratio in which the elastomer component (a) exists in the square area of is 5% or more."

The thickness of the surface treatment film of the present invention is preferably 0.05 μm to 2.00 μm. That is, if the film thickness is less than 0.05 μm, the corrosion resistance may become insufficient. On the other hand, if the film thickness is larger than 2.00 μm, the conductivity may become insufficient.

Subsequently, the components constituting the surface treatment film of the present invention will be explained in detail.
<Elastomer component (a)>
The elastomer component (a) contained in the surface treatment film of the present invention contains butadiene rubber in at least part of particles having an average diameter of 20 nm to 500 nm. In the surface treatment film of the present invention, the structure in which the elastomer component (a) is dispersed in the film mainly composed of a silicon compound provides the effect of densifying the film and improving the corrosion resistance of the planar portion. Furthermore, by including butadiene rubber as a part of the elastomer component (a), the effect of suppressing stress concentration during processing to improve the corrosion resistance of the processed part and the effect of suppressing side slip and coil collapse during lamination are exhibited. do. In addition, when the elastomer component (a) has an average particle size of 20 nm to 500 nm, the effect of improving the corrosion resistance of the processed part, the corrosion resistance of the flat part, and the skidding resistance during lamination is sufficiently exhibited. That is, when the average particle size of the elastomer component (a) is smaller than 20 nm, the effect of suppressing the contact between the wax and the mating material is lost, resulting in insufficient skidding resistance during lamination. On the other hand, if the average particle size of the elastomer component (a) is larger than 500 nm, the effect of suppressing stress concentration will be insufficient, and the corrosion resistance of processed parts will not be improved. Preferably, the average particle size is 50 nm to 300 nm.

The elastomer component (a) may contain elastomer particles other than butadiene rubber, but the ratio of the butadiene rubber elastomer particles to the entire elastomer component (a) is preferably 20% by mass or more. More preferably, it is 40% by mass or more. This is because if the proportion of the butadiene rubber elastomer in the elastomer component (a) is less than 20% by mass, the effect of improving the corrosion resistance of the processed part, the side slip resistance during lamination, and the coil crush resistance is reduced. be.

The average particle size of the elastomer component (a) in the surface treatment film can be calculated, for example, by the following method. First, the film surface is observed using a scanning electron microscope (SEM), and SEM images in the range of about 2 μm×2 μm are randomly photographed in five fields. In the resulting SEM image of the coating surface, the elastomer component (a) is observed as particles having a darker contrast than the surroundings (dark particles). Therefore, the particle diameters of all dark particles observed in the photographed SEM image are measured, and the area average is taken to calculate the average particle diameter. By calculating this average particle size for all five fields of view and averaging the three values, the average particle size of the elastomer component (a) in the film can be calculated.

The surface treatment film containing the elastomer component (a) is formed using an aqueous surface treatment liquid containing the elastomer emulsion (A) obtained by dispersing the elastomer component (a) in water.

In addition, the elastomer component (a) can contain elastomers other than butadiene rubber. More preferably, in addition to butadiene rubber, urethane rubber or polyurethane thermoplastic elastomer is also included. By containing the urethane rubber or polyurethane-based thermoplastic elastomer, the bonding strength between the base material and the surface treatment film is increased, and more excellent flat portion corrosion resistance and processed portion corrosion resistance can be obtained. When an elastomer other than butadiene rubber is included, the content ratio of the elastomer other than butadiene rubber is preferably less than 80% by mass. More preferably less than 60% by mass.

<Wax component (b)>
The wax component (b) contained in the surface treatment film of the present invention is present as flat particles in the film, thereby realizing excellent lubricity and skidding resistance. A surface treatment film containing a flattened wax component (b) is obtained by applying an aqueous surface treatment liquid containing wax (B) onto a zinc-based plated steel sheet, and further increasing the plate temperature to a temperature that is at least 10°C higher than the melting point of wax (B). It is obtained by drying under conditions such that the wax (B) is completely melted. The type of wax (B) used in the aqueous surface treatment liquid is not particularly limited, but polyethylene wax, oxidized polyethylene wax, oxidized polypropylene wax, paraffin wax, montan wax, microcrystalline wax and the like can be used.

<Silicon compound (c)>
The silicon compound (c) contained in the surface treatment film of the present invention is preferably 20.0% by mass to 50.0% by mass in terms of SiO ₂ . A surface treatment film containing 20.0% by mass to 50.0% by mass of the silicon compound (c) in terms of SiO ₂ is formed using an aqueous surface treatment liquid containing the silane compound (C). By containing 20.0% to 50.0% by mass of the silicon compound (c) in terms of SiO ₂ in the film, a film skeleton with high barrier properties is formed by siloxane bonds, resulting in excellent planar corrosion resistance. At the same time, excellent corrosion resistance of flat parts and corrosion resistance of processed parts can be obtained by a combined effect with the elastomer component (a). If the content of the silicon compound (c) is less than 20.0% by mass, the effect of improving the barrier properties of the film due to siloxane bonds may not be exhibited, and the corrosion resistance may become insufficient. On the other hand, when the content of the silicon compound (c) is more than 50.0% by mass, the combined effect with the elastomer component (a) is reduced, and there is a possibility that the flat portion corrosion resistance and the processed portion corrosion resistance may become insufficient.

<Phosphorus compound (d)>
The phosphorus compound (d) contained in the surface treatment film of the present invention is preferably 0.4% by mass to 8.0% by mass in terms of P. The phosphorus compound (d) in the surface treatment film of the present invention can be obtained by applying an aqueous surface treatment liquid containing a phosphonic acid compound (D) onto a zinc-based plated steel sheet and drying it. The phosphorus compound (d), being dispersed in the film, exerts a corrosion-inhibiting effect and improves the corrosion resistance of flat parts and the corrosion resistance of machined parts. Furthermore, it exerts a more excellent corrosion inhibiting action by interacting with the vanadium compound (e) and titanium compound (f) also contained in the film. If the phosphorus compound (d) contained in the film is less than 0.4% by mass in terms of P, the corrosion inhibiting action of the phosphorus compound (d) is not sufficiently exhibited, and the corrosion resistance of the flat part and the corrosion resistance of the processed part are poor. It is possible that it will be sufficient. On the other hand, when the phosphorus compound (d) is more than 8.0% by mass in terms of P, the elution property of the film increases, and there is a possibility that the corrosion resistance of the flat portion and the corrosion resistance of the processed portion deteriorate.

<Vanadium compound (e)>
The vanadium compound (e) contained in the surface treatment film of the present invention is preferably 0.1% by mass to 2.0% by mass in terms of V. The vanadium compound (e) in the surface treatment film of the present invention is obtained by applying an aqueous surface treatment liquid containing the vanadium compound (E) onto a zinc-based plated steel sheet and drying it. By being dispersed in the film, the vanadium compound (e) exhibits a corrosion-inhibiting action and improves the corrosion resistance of flat parts and the corrosion resistance of machined parts. Furthermore, the interaction with the phosphorus compound (d) and titanium compound (f), which are also contained in the film, exhibits a more excellent corrosion inhibiting action. If the vanadium compound (e) contained in the film is less than 0.1% by mass in terms of V, the corrosion inhibition effect of the vanadium compound (e) is not sufficiently exhibited, and the corrosion resistance of the flat part and the corrosion resistance of the processed part are insufficient. It is possible that it will be sufficient. On the other hand, if the vanadium compound (e) is more than 2.0% by mass in terms of V, the elution property of the film increases, and there is a possibility that the corrosion resistance of flat parts and the corrosion resistance of processed parts deteriorate.

Furthermore, the valence of vanadium in the vanadium compound (e) is more preferably tetravalent. When the valence of vanadium is tetravalent, the effect of suppressing the corrosion of the worked part is the highest, and the corrosion resistance of the worked part can be made more excellent. In order to suppress the corrosion of the processed part, it is necessary to ensure that vanadium is easily eluted from the film in a corrosive environment and that the eluted vanadium is precipitated at the damaged part of the film. The higher the valence of vanadium, the higher the elution of vanadium in a corrosive environment, but the lower the precipitation of eluted vanadium at the damaged portion of the film. The balance between the two is extremely good when vanadium is tetravalent, and it is considered that the corrosion inhibiting action of the processed portion is the highest. The valence of vanadium in the film can be measured using X-ray photoelectron spectroscopy or the like.

<Titanium compound (f)>
The titanium compound (f) contained in the surface treatment film of the present invention is preferably 0.1% by mass to 2.0% by mass in terms of Ti. The titanium compound (f) in the surface treatment film of the present invention is obtained by applying an aqueous surface treatment liquid containing the titanium compound (F) onto a zinc-based plated steel sheet and drying it. The titanium compound (f), being dispersed in the film, exhibits a corrosion-inhibiting effect and improves the corrosion resistance of the flat part and the corrosion resistance of the machined part. Furthermore, the interaction with the phosphorus compound (d) and vanadium compound (e), which are also contained in the film, exhibits a more excellent corrosion inhibiting action. If the titanium compound (f) contained in the film is less than 0.1% by mass in terms of Ti, the corrosion inhibiting effect of the titanium compound (f) is not sufficiently exhibited, and the corrosion resistance of the planar portion and the corrosion resistance of the processed portion are poor. It is possible that it will be sufficient. On the other hand, if the titanium compound (f) is more than 2.0% by mass in terms of Ti, the elution property of the film increases, and there is a possibility that the corrosion resistance of the flat portion and the corrosion resistance of the processed portion deteriorate.

The content of silicon compound (c) (in terms of _SiO2 ), phosphorus compound (d) (in terms of P), vanadium compound (e) (in terms of V), and titanium compound (f) (in terms of Ti) in the film is measured by fluorescence X It can be calculated by quantifying the amounts of Si, P, V, and Ti in the surface treatment film using line analysis. Also, the mass of the film can be calculated by peeling the film from the steel plate by acid treatment or the like and measuring the weight change before and after the peeling. As a result of examination by the present inventors, silicon compound (c) (in terms of _SiO2 ), phosphorus compound (d) (in terms of P), vanadium compound (e) (in terms of V), The amount of each component of the titanium compound (f) (in terms of Ti) is determined by the mass ratio of each component to the total solid content of the aqueous surface treatment liquid (silane compound (C) (in terms of _SiO2 ), phosphonic acid compound (D) (P conversion), vanadium compound (E) (V conversion), and titanium compound (F) (Ti conversion)). Therefore, the mass ratio of the silicon compound (c) (in terms of _SiO2 ), the phosphorus compound (d) (in terms of P), the vanadium compound (e) (in terms of V), and the titanium compound (f) (in terms of Ti) in the film is It can be regarded as the same as the mass ratio of each component to the total solid content of the aqueous surface treatment liquid.

2. Method for producing surface-treated steel sheet Next, a method for producing a zinc-based plated steel sheet with a surface-treated film according to the present embodiment will be described with an example. A zinc-based plated steel sheet with a surface treatment film is prepared by preparing a zinc-based plated steel sheet, and applying an aqueous surface treatment liquid containing each component contained in the surface treatment film of the present invention in a predetermined ratio on one or both sides of the zinc-based plated steel sheet. It is produced by forming a surface treatment film on a zinc-based plated steel sheet by applying it and drying it so that the sheet temperature reaches a predetermined temperature.

2.1 Water-Based Surface Treatment Liquid First, the water-based surface treatment liquid used in this embodiment will be described. In the present embodiment, for example, as the aqueous surface treatment liquid, an elastomer emulsion (A) containing butadiene rubber, a wax (B), a silane compound (C), a phosphonic acid compound (D), and a vanadium compound (E) , a titanium compound (F), and water under the following conditions [I] and [II] and having a pH of 3.0 to 7.0.

<Elastomer emulsion (A) containing butadiene rubber>
In order to incorporate the elastomer component (a) containing butadiene rubber into the surface treatment film, the elastomer emulsion (A) containing butadiene rubber is added to the aqueous surface treatment liquid of the present embodiment. The elastomer emulsion (A) containing butadiene rubber is dispersed as particles in the water-based surface treatment liquid. The average particle size of the elastomer emulsion (A) containing butadiene rubber in the aqueous surface treatment liquid is adjusted to 20 nm to 500 nm. For this adjustment, for example, in addition to an elastomer emulsion containing butadiene rubber having an average particle size of 20 nm to 500 nm, a surfactant such as polyoxyethylene fatty acid diester is added to aggregate the emulsion in the aqueous surface treatment liquid. can be done by suppressing

As a result, the average particle size of the elastomer component (a) contained in the film is also 20 nm to 500 nm, and excellent corrosion resistance of processed parts and anti-skidding property during lamination can be realized. The butadiene rubber in the elastomer emulsion (A) containing butadiene rubber includes at least one of styrene-butadiene rubber elastomer (SBR), methyl methacrylate-butadiene rubber elastomer (MBR), and acrylonitrile-butadiene rubber elastomer (NBR). preferably include

Furthermore, the elastomer emulsion (A) must be compounded under the following conditions [I].
[I] The ratio (A _S )/(NV) of the mass (A _S ) of the solid content of the elastomer emulsion (A) containing the butadiene rubber to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.0. 05 to 0.45
<(A _S )/(NV)>
The ratio (A _S )/(NV) of the solid content mass (A _S ) of the elastomer emulsion (A) containing the butadiene rubber to the total solid content mass (NV) of the aqueous surface treatment liquid is 0.05 to 0.45. Preferably, it is 0.10 to 0.40. That is, when (A _S )/(NV) is in the range of 0.05 to 0.45, the presence of the elastomer component (a) in the region where the wax component (b) does not exist on the surface of the film Since it is possible to realize a film having a "covering area ratio of 5% to 50%", the corrosion resistance of the flat part, the corrosion resistance of the processed part, and the side slip resistance during lamination are sufficient.

In addition to butadiene rubber, it is more desirable to add urethane rubber or polyurethane-based thermoplastic elastomer to the water-based surface treatment liquid of the present embodiment. The urethane rubber or polyurethane-based thermoplastic elastomer is added to the water-based surface treatment liquid as necessary, and may not be included. If urethane rubber or polyurethane thermoplastic elastomer is added to the aqueous surface treatment liquid, the urethane rubber or polyurethane thermoplastic elastomer will be included as an elastomer component in the film, further improving corrosion resistance. As the urethane rubber or polyurethane-based thermoplastic elastomer, particles having an average particle size of 20 nm to 500 nm in the water-based surface treatment liquid are used. As a result, the average particle size of the elastomer component (a) contained in the film is also 20 nm to 500 nm, and excellent corrosion resistance of flat portions, corrosion resistance of processed portions, and anti-skidding property during lamination can be realized.

<Wax (B)>
In order to make the surface treatment film contain the wax component (b), the wax (B) is added to the aqueous surface treatment liquid of the present embodiment. The type of wax (B) is not particularly limited, but polyethylene wax, oxidized polyethylene wax, oxidized polypropylene wax, paraffin wax, montan wax, microcrystalline wax and the like can be used. More preferably, wax having a melting point of 140° C. or less is used in order to promote melting of the wax and formation of flat particles on the film surface.

Furthermore, the wax (B) must be blended under the following conditions [II].
[II] The ratio (B _S )/(NV) of the solid content (B _S ) of the wax (B) to the total solid content (NV) of the aqueous surface treatment liquid is 0.003 to 0.050.
<(BS)/( _NV )>
The ratio (B _S )/(NV) of the solid content (B _S ) of the wax (B) to the total solid content (NV) of the aqueous surface treatment liquid is 0.003 to 0.050. . More preferably, it is 0.040 or less. That is, when (B _S )/(NV) is in the range of 0.003 to 0.050, "the area ratio of the region where the wax component (b) is present on the coating surface is 2% to 40%. As a result, sufficient lubricity and side-slip resistance during lamination can be achieved.

<Silane compound (C)>
As a precursor of the silicon compound (c) contained in the surface treatment film, the silane compound (C) is added to the aqueous surface treatment liquid of the present embodiment. The silane compound (C) is silanolized by hydrolysis in the process of applying the water-based surface treatment liquid to the zinc-based plated steel sheet and drying it, forming a siloxane-type film that is three-dimensionally crosslinked by siloxane bonds. Furthermore, when the silane compound (C) forms a film, the elastomer component ( Since a structure in which a) is dispersed as fine particles is formed, the corrosion resistance of the processed part can be improved.

As the silane compound (C), it is preferable to use at least one of a silane coupling agent and a tetraalkoxysilane, more preferably both a silane coupling agent and a tetraalkoxysilane. By using both the silane coupling agent and the tetraalkoxysilane, it becomes possible to obtain a denser film.

Silane coupling agents include, for example, N-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane. Silane, 2-(3,4 epoxycyclohexyl)ethyltrimethoxysilane, vinyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, p-styryltri Methoxysilane or the like can be used. Among them, it is preferable to use a trialkoxysilane having at least one reactive functional group selected from an active hydrogen-containing amino group, an epoxy group, a vinyl group, a mercapto group and a methacryloxy group, and further having three alkoxy groups. desirable from this point of view. Examples of such silane coupling agents include N-(aminoethyl)3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyl Methyldimethoxysilane, 2-(3,4 epoxycyclohexyl)ethyltriethoxysilane, vinyltriethoxysilane, 3-mercaptopropyltrimethoxysilane and the like can be used.

As tetraalkoxysilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and the like can be used. Among them, tetraethoxysilane and tetramethoxysilane are preferable from the viewpoint of more excellent corrosion resistance of plane portions.

<Phosphonic acid compound (D)>
As a precursor of the phosphorus compound (d) contained in the surface treatment film, a phosphonic acid compound (D) is added to the aqueous surface treatment liquid of the present embodiment. By using a surface treatment liquid containing a phosphonic acid compound (D), a structure in which the phosphorus compound (d) is dispersed in the film is formed, and the corrosion inhibition effect improves the corrosion resistance of the flat part and the corrosion resistance of the processed part.

In addition, when the phosphonic acid compound (D) is contained in the surface treatment liquid, its emulsifying action can realize a structure in which the elastomer component (a) is dispersed as fine particles in the film mainly composed of the silicon compound (c). . When the phosphonic acid compound (D) is not contained, the elastomer emulsion (A) containing butadiene rubber, which is the precursor of the elastomer component (a), is aggregated in the surface treatment liquid, so that the elastomer component (a) is A structure in which fine particles are dispersed in a film mainly composed of the silicon compound (c) cannot be realized.

The phosphonic acid compound (D) is not particularly limited, but in addition to phosphonic acid, aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, hexamethylenediaminetetramethylenephosphonic acid, 1-hydroxymethane-1,1-diphosphonic acid. , 1-hydroxyethane-1,1-diphosphonic acid, or salts thereof. Among these, 1-hydroxymethane-1,1-diphosphonic acid and 1-hydroxyethane-1,1-diphosphonic acid are particularly desirable because they are highly effective in dispersing the elastomer in the treatment liquid in the film due to their emulsifying action. .

<Vanadium compound (E)>
As a precursor of the vanadium compound (e) contained in the surface treatment film, the vanadium compound (E) is added to the aqueous surface treatment liquid of the present embodiment. Examples of the vanadium compound (E) include ammonium metavanadate, sodium metavanadate, vanadyl acetylacetonate, vanadyl sulfate and the like, and one or more of these can be used. Among these, it is particularly desirable to use vanadyl compounds such as vanadyl acetylacetonate and vanadyl sulfate. By using a vanadyl compound as the vanadium compound (E), the valence of the vanadium compound (e) contained in the film becomes tetravalent, resulting in better corrosion resistance of the worked part.

<Titanium compound (F)>
As a precursor of the titanium compound (f) contained in the surface treatment film, the titanium compound (F) is added to the aqueous surface treatment liquid of the present embodiment. Examples of the titanium compound (F) include titanyl sulfate, titanyl nitrate, titanium nitrate, titanyl chloride, titanium chloride, titania sol, titanium oxide, potassium oxalate titanate, titanium hydrofluoric acid, titanium ammonium fluoride, titanium lactate, titanium tetra Isopropoxide, titanium acetylacetonate, diisopropyl titanium bisacetylacetone and the like can be used. Also included are metatitanic acid obtained by thermally hydrolyzing an aqueous solution of titanyl sulfate, orthotitanic acid obtained by alkali neutralization, and salts thereof.

Preferred compounding ratios of the silane compound (C), phosphonic acid compound (D), vanadium compound (E) and titanium compound (F) components contained in the aqueous surface treatment liquid used in the present embodiment are as follows [III ] to [VI].
[III] The ratio (C _SiO2 )/(NV) of the mass (C _SiO2 ) of the silane compound (C) in terms of SiO ₂ to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.20 to 0.50
[IV] The ratio (D _P )/(NV) of the P-converted mass (D _P ) of the phosphonic acid compound (D) to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.004 to 0.080
[V] The ratio (E _V )/(NV) of the V-equivalent mass (E _V ) of the vanadium compound (E) to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.001 to 0. .020
[VI] The ratio (F _Ti )/(NV) of the Ti-equivalent mass (F _Ti ) of the titanium compound (F) to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.001 to 0. .020

<( _CSiO2 )/(NV)>
The ratio (C _SiO2 )/(NV) of the SiO ₂ equivalent mass (C _SiO2 ) of the silane compound (C) to the total solid mass (NV) of the aqueous surface treatment liquid is 0.20 to 0.50. is preferably By blending the silane compound (C) such that (C _SiO2 )/(NV) is 0.20 to 0.50, "the elastomer component (a) is dispersed as particles in the film, Furthermore, since a film containing 20.0% by mass to 50.0% by mass of the silicon compound (c) in terms of SiO ₂ can be realized, the corrosion resistance of the planar portion and the corrosion resistance of the processed portion are sufficient. When (C _SiO2 )/(NV) is less than 0.20, the silicon compound (c) contained in the film has a SiO ₂ equivalent mass of less than 20% by mass, and the siloxane bond has the effect of increasing the barrier properties of the film. Since it will not be exhibited, there is a possibility that the corrosion resistance of the flat part will be insufficient. On the other hand, if (C _SiO2 )/(NV) is greater than 0.50, the silicon compound (c) contained in the film will have a mass equivalent to SiO ₂ of more than 50.0% by mass. The combined effect of the above is lost, and the corrosion resistance of the flat portion and the corrosion resistance of the processed portion may become insufficient.

<( _DP )/(NV)>
The ratio (D _P )/(NV) of the P-converted mass (D _P ) of the phosphonic acid compound (D) to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.004 to 0.080. is preferably Since (D _P )/(NV) is 0.004 to 0.080, the P conversion mass of the phosphorus compound (d) contained in the film is 0.4% to 8.0% by mass. , excellent corrosion resistance of flat parts and processed parts can be realized due to its corrosion suppression effect.

<(EV)/( _NV )>
The ratio (E _V )/(NV) of the V-converted mass (E _V ) of the vanadium compound (E) to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.001 to 0.020. Preferably. Since (E _V )/(NV) is 0.001 to 0.020, the V conversion mass of the vanadium compound (e) contained in the film is 0.1% to 2.0% by mass. , excellent corrosion resistance of flat parts and processed parts can be realized due to its corrosion suppression effect.

<( _FTi )/(NV)>
The ratio (F _Ti )/(NV) of the Ti-converted mass (F _Ti ) of the titanium compound (F) to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.001 to 0.020. Preferably. When (F _Ti )/(NV) is 0.001 to 0.020, the Ti-equivalent mass of the titanium compound (f) contained in the film is 0.1 mass% to 2.0 mass%. Therefore, due to its corrosion suppression effect, it is possible to realize excellent flat surface corrosion resistance and machined portion corrosion resistance.

<pH>
The pH of the aqueous surface treatment liquid should be 3.0 to 7.0. More preferably, it is 4.0 to 6.0. When the pH of the surface treatment liquid is in the range of 3.0 to 7.0, the elastomer particles are dispersed in the film, so excellent corrosion resistance of the processed part can be obtained. Further, when the pH is in the range of 4.0 to 6.0, the elastomer particles are dispersed more uniformly in the film, so that better flat part corrosion resistance and processed part corrosion resistance can be obtained. In the present invention, the alkali used for pH adjustment is preferably ammonium, amines, amine derivatives and aminopolycarboxylic acids, and the acid used for pH adjustment is preferably volatile acids such as formic acid and acetic acid.

Moreover, the water-based surface treatment liquid of the present invention can be obtained by mixing the above components in water such as deionized water or distilled water. The solid content ratio of the surface treatment liquid may be appropriately selected. The water-based surface treatment liquid of the present invention includes surfactants and thickeners called wettability improvers for forming a uniform film on the surface to be coated, conductive substances for improving conductivity, design A coloring pigment for improving properties, a solvent for improving film-forming properties, and the like may be appropriately added as necessary. Alcohol, ketones, cellosolve-based water-soluble solvents, surfactants, antifoaming agents, leveling agents, antibacterial and antifungal agents, colorants, and the like may be added to the aqueous surface treatment liquid, if necessary. By adding these, the drying properties, coating appearance, workability, storage stability (storage stability), and design properties of the surface treatment liquid are improved. However, it is important to add these to such an extent that the quality obtained in the present invention is not impaired, and the amount added is at most less than 5% by mass based on the total solid content of the surface treatment liquid.

2.2 Film Formation Method In the present embodiment, the aqueous surface treatment liquid thus obtained is applied onto a zinc-based plated steel sheet and dried by heating to form a surface treatment film. Examples of the method for applying the surface treatment solution to the zinc-based plated steel sheet include a roll coating method, a bar coating method, an immersion method, and a spray coating method. is selected. More specifically, for example, if the galvanized steel sheet to be treated is in the form of a sheet, a roll coating method, a bar coating method, or a surface treatment liquid is sprayed on the galvanized steel sheet and then rolled or gas is sprayed at high pressure. to adjust the coating amount. If the zinc-based plated steel sheet is a molded product, a method of immersing it in the surface treatment solution and pulling it up, depending on the case, blowing off excess surface treatment solution with compressed air to adjust the coating amount is selected. .

In addition, before applying the surface treatment liquid to the galvanized steel sheet, if necessary, the galvanized steel sheet may be pretreated for the purpose of removing oil and dirt on the surface of the galvanized steel sheet. good. Zinc-based plated steel sheets are often coated with antirust oil for the purpose of rust prevention, and even when they are not coated with antirust oil, there is oil and dirt attached during work. These oils, oils, and stains inhibit the wettability of the surface of the zinc-based plating layer and interfere with the formation of a uniform first layer coating. The surface of the plating layer is cleaned and uniformly wettable. If the surface of the zinc-based plated steel sheet is free from oil and stains and is evenly wetted with the surface treatment liquid, the pretreatment step is not particularly necessary. The pretreatment method is not particularly limited, and examples thereof include hot water washing, solvent washing, alkaline degreasing washing, and the like.

The heating temperature (maximum plate temperature) when heat-drying the surface treatment solution applied to the surface of the zinc-based plating layer is a temperature higher than the melting point of the wax (B) by 10° C. or more, more preferably the wax (B). at least 20°C higher than the melting point of By setting the temperature to 10° C. or more higher than the melting point of the wax (B), the wax (B) melts and forms flat particles on the surface of the coating, resulting in a coating with excellent lubricity. However, in order to evaporate the moisture in the film, it should be dried at least at 60°C or higher. When using a plurality of kinds of waxes, it is preferable that the melting point is higher than the melting point of the wax having the highest melting point.

Also, the optimum heating time is appropriately selected depending on the type of zinc-based plated steel sheet to be used. From the viewpoint of productivity, the time is preferably 0.1 to 60 seconds, more preferably 1 to 30 seconds.
Through the above steps, the surface-treated steel sheet of the present embodiment is obtained.

Next, examples of the present invention will be described. In addition, the present invention is not limited to the examples shown below.
1. Method of preparing test plate 1.1 Test plate (material)
The following commercially available materials were used as test plates.
(I) Electrogalvanized steel sheet (EG): sheet thickness 0.8 mm, basis weight 20/20 (g/m ² )
(II) Hot-dip galvanized steel sheet (GI): sheet thickness 0.8 mm, basis weight 60/60 (g/m ² )
(III) Galvannealed steel sheet (GA): plate thickness 0.8 mm, basis weight 40/40 (g/m ² )
In addition, the basis weight indicates the basis weight on the main surface of each steel plate. For example, in the case of an electrogalvanized steel sheet (20/20 (g/m ² )), it means that each of both sides of the steel sheet has a coating layer of 20 g/m ² .

1.2 Pretreatment (washing)
As a method for preparing the test piece, first, the surface of the above test material was treated using Palclean N364S manufactured by Nihon Parkerizing Co., Ltd. to remove oil and dirt on the surface. Next, after washing with tap water and confirming that the surface of the test plate is 100% wet with water, pure water (deionized water) was poured over it, and the moisture was dried in an oven at 100°C, and the test was performed. used as pieces.

1.3 Preparation of surface treatment liquid Each component was mixed in water in the composition shown in Table 1 (mass ratio to total solid content) to obtain a surface treatment liquid for a galvanized steel sheet. In addition, A _S , B _S , C _SiO2 , D _P , E _V and F _Ti in Table 1 are the mass of the solid content of the butadiene rubber-containing elastomer emulsion (A) and the solid content of the wax (B), respectively. Mass, mass of silane compound (C) converted to _SiO2 , mass of phosphonic acid compound (D) converted to P, mass of vanadic acid compound (E) converted to V, and mass of titanium compound (F) converted to Ti. . Also, the pH of the surface treatment liquid was adjusted to the value shown in Table 1 using acetic acid or ammonia.

The compounds used in Table 1 are described below.
<Elastomer (A) containing butadiene rubber>
A1: Styrene-butadiene rubber elastomer (average particle size 180 nm)
A2: Methyl methacrylate-butadiene rubber elastomer (average particle size 150 nm)
A3: Acrylonitrile-butadiene rubber elastomer (average particle size 130 nm)
A4: Styrene-butadiene rubber elastomer (average particle size 700 nm)
A5: Urethane rubber elastomer (average particle size 10 nm)
A6: Urethane rubber elastomer (average particle size 60 nm)

<Wax (B)>
B1: Polyethylene wax (melting point 120°C)
B2: Microcrystalline wax (melting point 90°C)

<Silane compound (C)>
C1: γ-glucidyltriethoxysilane C2: 3-mercaptopropyltrimethoxysilane C3: N-(2-aminoethyl)-3-aminopropyltrimethoxysilane C4: tetraethoxysilane C5: colloidal silica

<Phosphonic acid compound (D)>
D1: 1-hydroxymethane-1,1-diphosphonic acid D2: phosphonic acid
D3: disodium hydrogen phosphate

<Vanadium compound (E)>
E1: ammonium metavanadate E2: vanadyl acetylacetonate (V: 19.2%)

<Titanium compound (F)>
F1: titanium ammonium fluoride F2: titanium acetylacetonate (Ti: 12.5%)

1-4. Treatment method Using the above surface treatment solution for zinc-based plated steel sheets, each test plate is coated with a bar coat, and then placed in an oven as it is without washing with water, and dried at the drying temperature shown in Table 2. It was dried to form a surface treatment film having a film amount shown in Table 2. The drying temperature was adjusted by the ambient temperature in the oven and the time in the oven. The drying temperature is shown as the temperature reached on the surface of the test plate (ultimate plate temperature). A specific method of bar coat coating is as follows.

Bar coat coating: The treatment solution was dropped onto the test panel and coated with a #3-8 bar coater. The thickness of the coating was adjusted to a predetermined thickness depending on the number of the bar coater used and the solid content concentration of the treatment liquid. The film thickness was obtained by observing the cross section of the steel sheet after the formation of the surface treatment film with a scanning electron microscope (SEM).

2. Evaluation The surface-treated steel sheets of Examples and Comparative Examples thus obtained were evaluated according to the following items (1) to (11).

2.1 Film property evaluation (1) Presence and content of each component in the film Silicon compound (c) (in terms of _SiO2 ), phosphorus compound (d) (in terms of P), vanadium compound (e) (V As described above, the mass ratio of the titanium compound (f) (in terms of Ti) and the titanium compound (f) (in terms of Ti) is the same as the mass ratio to the total solid content of the aqueous surface treatment liquid. ) to (1-4).
(1-1) SiO ₂ conversion mass ratio of silicon compound (c) in the film 1: less than 20.0 mass% or more than 50.0 mass% 2: 20.0 mass% to 50.0 mass% Contained in the range of 0% by mass 3: Not contained in the film (1-2) The mass ratio of phosphorus compound (d) in the film in terms of P 1: less than 0.4% by mass or 8.0% by mass Contained in the range exceeding 2: Contained in the range of 0.4 mass% to 8.0 mass% 3: Not contained in the coating (1-3) V-converted mass ratio of vanadium compound (e) in the coating 1: Contained in the range of less than 0.1 mass% or more than 2.0 mass% 2: Contained in the range of 0.1 mass% to 2.0 mass% 3: Not contained in the coating (1-4 ) The Ti-equivalent mass ratio of the titanium compound (f) in the film is 1: less than 0.1% by mass or more than 2.0% by mass, 2: in the range of 0.1% to 2.0% by mass Included in 3: Not included in the film

In addition, the film was peeled off from each steel plate by acid treatment, and infrared spectroscopic analysis and pyrolysis GC-MS (gas chromatograph-mass spectrometer) analysis were performed. Then, from the result of analysis from the attribution of the observed absorption derived from the resin component in the infrared absorption spectrum of the film obtained by infrared spectroscopic analysis and the result of pyrolysis GC-MS, the presence of butadiene rubber in the film and urethane The presence of rubber or urethane thermoplastic elastomer was confirmed and evaluated according to the following items (1-5).
(1-5) Presence of butadiene rubber in film 1: Film does not contain butadiene rubber 2: Film contains butadiene rubber but does not contain urethane rubber or urethane thermoplastic elastomer 3: Film Contains butadiene rubber, urethane rubber or urethane thermoplastic elastomer

(2) Area ratio of flattened wax particles on film surface The surface of the film was observed using a scanning electron microscope (SEM) at an accelerating voltage of 0.5 kV, and the SEM in the range of 20 µm × 20 µm was observed. Images were taken randomly in 5 fields. In the SEM image of the obtained film surface, the presence or absence of flat-shaped wax particles observed with dark contrast was confirmed. Furthermore, when flat-shaped wax particles were present, the photographed SEM image was binarized by image processing, and the area ratio of the flat-shaped particles was calculated. Then, this was carried out in all of the extracted five fields of view, and by taking the average, the area ratio of the region where the wax component was present on the surface of the surface treatment film was calculated and evaluated as follows.
1: Flat-shaped wax particles are not observed 2: Flat-shaped wax particles are observed and the area ratio on the coating surface is less than 2% 3: Flat-shaped wax particles are observed and the area ratio on the coating surface is more than 40% 4: Flat-shaped wax particles are observed, and the area ratio on the film surface is 2% or more and 40% or less

(3) Average particle size of elastomer particles on film surface Using a scanning electron microscope (SEM), the film surface was observed at an accelerating voltage of 0.5 kV. SEM images in the range of 5 were randomly photographed. The presence or absence of elastomer particles having a darker contrast than the surroundings was confirmed in the SEM image of the resulting film surface. Then, when elastomer particles having a dark contrast were present, the particle diameters of all the dark particles observed in the photographed SEM image were measured and averaged to calculate the average particle diameter. The average particle size of the elastomer component in the film was calculated by calculating the average particle size for all five fields of view and averaging the three values. Based on these results, evaluation was made as follows.
1: Elastomer particles are not observed 2: Elastomer particles are observed and the average particle size is less than 20 nm 3: Elastomer particles are observed and the average particle size is more than 500 nm 4: Elastomer particles are present and the average particle size is 20 nm or more and 500 nm Less than

(4) Area ratio occupied by elastomer particles in regions where no wax component exists on the film surface Observe the film surface under conditions of an acceleration voltage of 0.5 kV using a scanning electron microscope (SEM) to obtain flattened wax particles. SEM images in the range of 2 μm×2 μm were randomly photographed from 5 fields of view from the region where there was no . In the obtained SEM image of the film surface, the SEM image taken was binarized by image processing, and the area ratio of dark particles corresponding to the elastomer component was calculated. Then, this was carried out for all five extracted fields of view, and the average was taken to calculate "the area ratio of the elastomer particles in the region where the wax component does not exist on the surface of the surface treatment film". Based on the obtained values, evaluation was made as follows.
1: Area ratio occupied by elastomer particles is less than 5% 2: Area ratio occupied by elastomer particles exceeds 50% 3: Area ratio occupied by elastomer particles is 5% or more and 50% or less

(5) Dispersion state of elastomer particles on the film surface Using a scanning electron microscope (SEM), the film surface was observed at an acceleration voltage of 1 kV, and a square area of 1 μm × 1 μm was randomly selected from the area where no flat wax particles were present. 10 fields of view were extracted. In the obtained SEM image of the film surface, the SEM image taken was binarized by image processing, and the area ratio of dark particles corresponding to the elastomer component was calculated. Then, this was performed in all of the extracted 10 fields of view, and the calculated values were used for evaluation as follows.
The area ratio of the elastomer particles is less than 5% in any of the 1:10 visual fields, and the above area ratio is 5% or more in all of the 2:10 visual fields.

(6) Area ratio of wax component inside the film The surface of the film was observed with a scanning electron microscope (SEM) at an acceleration voltage of 3 kV, and 5 SEM images in the range of 20 µm × 20 µm were randomly selected. Field of view photographed. In the SEM image of the obtained film surface, the presence or absence of flat-shaped wax particles observed with dark contrast was confirmed. Furthermore, when flat-shaped wax particles were present, the photographed SEM image was binarized by image processing, and the area ratio of the flat-shaped particles was calculated. Then, this was carried out in all of the extracted five fields of view, and by taking the average, the area ratio of the region where the wax component was present inside the surface treatment film was calculated and evaluated as follows.
1: The area ratio of the region where the wax component exists inside the surface treatment film is 1% or more 2: The area ratio of the region where the wax component exists inside the surface treatment film is less than 1%

2.2 Performance evaluation (7) A test piece with a size of 70 mm × 150 mm was cut out from each test plate on which the flat part corrosion-resistant film was formed, and the back and edges of each cut test piece were sealed with vinyl tape, and JIS- A salt spray test (SST) according to Z-2371-2000 was performed. Corrosion resistance was evaluated based on the following evaluation criteria by visually observing the area ratio of white rust after 144 hours of the salt spray test.
Evaluation criteria:
◎: less than 1% white rust area rate +: 1% to less than 5% white rust area rate ○: 5% to less than 20% white rust area rate △: 20% to less than 40% white rust area rate ×: white rust generation area ratio of 40% or more

(8) A test piece of size 70 mm × 150 mm was cut out from each test plate on which a corrosion-resistant film was formed on the processed part, and the back and ends of each cut test piece were sealed with vinyl tape. It was bent 180° so as to be sandwiched between the two (made by the manufacturer), and tightened using a vise. The bent sample was subjected to a salt spray test (JIS-Z-2371-2000), and the area ratio of white rust generated on the outside (front) side of the bent portion after 72 hours was evaluated.
Evaluation criteria:
◎ : less than 1% white rust generated area ratio of bent portion ○ + : 1% or more and less than 5% white rust generated area ratio of bent portion ○ : 5% or more and less than 10% white rust generated area ratio of bent portion △ : 10% or more and less than 80% of the white rust occurrence area ratio of the bent portion ×: 80% or more of the white rust occurrence area ratio of the bent portion

(9) Continuity The surface resistance value of the above test piece was measured using Loresta GP and ESP terminals manufactured by Mitsubishi Chemical Analytic Tech. The surface resistance value was measured by increasing the load applied to the terminal by 50 g intervals, and the continuity was evaluated by determining the minimum load that can reduce the surface resistance value to 10 −4 Ω or less.
Evaluation criteria:
◎: Average load of 10-point measurement is less than 300g ○: Average load of 10-point measurement is 300g or more and less than 750g △: Average load of 10-point measurement is 750g or more and less than 950g ×: Average load of 10-point measurement is 950g or more

(10) Lubricity Lubricity was evaluated using the dynamic friction coefficient μ of each test material obtained as follows. FIG. 1 is a schematic front view showing a dynamic friction coefficient measuring device. As shown in the figure, a friction coefficient measurement sample 1 (hereinafter referred to as sample 1) taken from a test material is fixed to a sample table 2, and the sample table 2 is fixed to the upper surface of a horizontally movable slide table 3. It is A vertically movable slide table support 5 having a roller 4 in contact with the slide table 3 is provided on the lower surface of the slide table 3. By pushing this up, a pressing load N A first load cell 7 for measuring is attached to the slide table support base 5 . A second load cell 8 for measuring the sliding resistance force F for moving the slide table 3 in the horizontal direction with the pressing force applied is placed above the rail 9 at one end of the slide table 3. installed.

FIG. 2 is a schematic perspective view showing the shape and dimensions of the beads used. The lower surface of the bead 6 slides against the surface of the sample 1 . The shape of the bead 6 shown in FIG. 2 has a width of 10 mm, a length of 12 mm in the sliding direction of the sample 1, lower portions of both ends in the sliding direction are curved surfaces having a curvature of 4.5 mmR, and a lower surface of the bead against which the sample 1 is pressed has a width of 10 mm. It has a plane with a length of 3 mm in the sliding direction.

The friction coefficient measurement test was performed using the bead shown in FIG. 2 under the conditions of a pressing load N of 400 kgf and a sample withdrawal speed (horizontal movement speed of the slide table 3) of 100 cm/min.

The dynamic friction coefficient μ between the test material and the bead was calculated by the formula: μ=F/N. It can be evaluated that the smaller the coefficient of dynamic friction μ, the better the lubricity. Specifically, evaluation was made according to the following criteria.
Evaluation criteria:
◎: friction coefficient μ is less than 0.15 ○: friction coefficient μ is 0.15 or more and less than 0.20 △: friction coefficient μ is 0.20 or more and less than 0.25 ×: friction coefficient μ is 0.25 or more

(11) Side-slip resistance during lamination The side-slip resistance during lamination was evaluated using the coefficient of static friction μ ₀ at the beginning of slipping of each test material, which was obtained by the following method. FIG. 3 is a schematic front view showing a static friction coefficient measuring device at the start of slipping. As shown in the figure, three sheets of friction coefficient measurement samples taken from the test material are stacked. Samples 10-1, 10-2, and 10-3 are hereinafter referred to from the left. The sample 10-1 and the sample 10-3 are fixed by a holding jig 11. FIG. Beads 12-1 and 12-2 are arranged on the left side of the sample 10-1 and the right side of the sample 10-3. A first load cell 13 for measuring the pressing load N is attached. The size of the portion where the beads 12-1 and 12-2 contact the samples 10-1 and 10-3 is a plane with a width of 30 mm and a length of 35 mm in the sliding direction. A second load cell 14 is attached to the top of the sample 10-2 in order to measure the sliding resistance force F when the sample 10-2 is pulled upward while the pressing load N is applied.

The coefficient of static friction μ ₀ at the start of sliding of each sample is calculated by the formula: μ ₀ = F ₀ /N using the pressing load N and the sliding resistance force F ₀ when the sample 10-2 starts to slide. did. It can be evaluated that the larger the coefficient of friction μ ₀ at the start of slipping, the better the side-slip resistance during lamination. Specifically, evaluation was made according to the following criteria.
Evaluation criteria:
◎: friction coefficient μ ₀ at the start of sliding is 0.15 or more ○: friction coefficient μ ₀ at the start of sliding is 0.10 or more and less than 0.15 △: friction coefficient μ ₀ at the start of sliding is 0.08 or more and less than 0.10 ×: Friction coefficient μ ₀ at the beginning of slipping is less than 0.08

Tables 3 and 4 show the above results.

As shown in Tables 3 and 4, the zinc-based steel sheets with the surface treatment film of the present invention all exhibit excellent performance in terms of corrosion resistance, conductivity, lubricity, side slip resistance during lamination, and coil crush resistance. have. On the other hand, in the comparative examples in which any of the requirements deviated from the appropriate range of the present invention, any of the corrosion resistance, adhesion, conductivity and lubricity, side slip resistance during lamination and coil crush resistance was insufficient. there were.

Also, No. The surface of the surface-treated steel sheet No. 14 (Invention Example) was observed with a scanning electron microscope (SEM) at an acceleration voltage of 0.5 kV to obtain an SEM image of the coating surface. FIG. 14 (invention example) surface SEM image in the range of 20 μm × 20 μm, FIG. 14 (invention example) surface SEM image in the range of 2 μm × 2 μm.

From FIG. In 14 (Invention Example), flat wax particles with dark contrast are present on the surface of the surface treatment film, and the area ratio of the region in which the wax component exists on the surface of the surface treatment film is 2% to 40%. One thing has been confirmed. Also, from FIG. In 14 (Invention Example), elastomer particles with dark contrast are present and have an average particle diameter of 20 nm to 500 nm, and the region where the elastomer component exists among the regions where the wax component does not exist on the surface of the surface treatment film. was confirmed to be 5% to 50%.

Furthermore, No. 28 (comparative example) and No. The surface of the surface-treated steel sheet No. 26 (comparative example) was observed with a scanning electron microscope (SEM) at an acceleration voltage of 0.5 kV to obtain an SEM image of the coating surface. FIG. 28 (comparative example) surface SEM image in the range of 20 μm × 20 μm, FIG. 26 (comparative example) is a surface SEM image of a 2 μm×2 μm area.

From FIG. 6, No. In No. 28 (comparative example), it was confirmed that the area ratio of dark-contrast flattened wax particles on the film surface was less than 2%. From FIG. In 26 (comparative example), the area percentage of dark contrast elastomer particles was found to be less than 5%.

1 Sample 2 Sample table 3 Slide table 4 Roller 5 Slide table support 6 Bead 7 First load cell 8 Second load cell 9 Rails 10-1, 10-2, 10-3 Sample 11 Holding jigs 12-1, 12-2 Bead 13 1st load cell

Galvanized steel sheet that does not contain pollution control substances such as hexavalent chromium in the coating, has excellent conductivity, corrosion resistance, and lubricity, and is also excellent in anti-side slip and anti-coil collapse resistance during lamination. can provide. Therefore, the zinc-based plated steel sheet produced by the production method of the present invention is extremely useful as parts for automobiles, home appliances, OA equipment, and the like.

Claims (11)

A zinc-based plated steel sheet having a surface treatment film on a zinc-based plating layer, the surface treatment film comprising:
an elastomer component (a) containing butadiene rubber as at least a portion of particles having an average particle size of 20 nm to 500 nm;
a wax component (b) having a flattened shape;
a silicon compound (c);
a phosphorus compound (d);
a vanadium compound (e);
a titanium compound (f);
including
The area ratio of the region where the wax component (b) exists on the surface of the surface treatment film is 2% to 40%, and the area of the elastomer component (a) in the region where the wax component (b) does not exist. A zinc-based plated steel sheet with a surface treatment film, wherein the ratio is 5% to 50%. In the surface treatment film, the silicon compound (c) is 20.0% by mass to 50.0% by mass in terms of SiO ₂ , and the phosphorus compound (d) is 0.4% by mass to 8.0% by mass in terms of P. %, 0.1% by mass to 2.0% by mass of the vanadium compound (e) in terms of V, and 0.1% to 2.0% by mass of the titanium compound (f) in terms of Ti. Item 1. A zinc-based plated steel sheet with a surface treatment film according to item 1. The zinc-based plated steel sheet with a surface treatment film according to claim 1 or 2, wherein the vanadium in the vanadium compound (e) has a valence of 4. 4. The area ratio of the elastomer component (a) according to any one of claims 1 to 3, in a square region of 1 μm×1 μm extracted from the region where the wax component (b) does not exist, is 5% or more. Galvanized steel sheet with surface treatment film. The zinc-based plating with a surface treatment film according to any one of claims 1 to 4, wherein the area ratio of the region where the wax component (b) exists in the surface treatment film is less than 1%. steel plate. The zinc-based plated steel sheet with a surface treatment film according to any one of claims 1 to 5, wherein said elastomer component (a) further contains urethane rubber or polyurethane-based thermoplastic elastomer. An elastomer emulsion (A) containing butadiene rubber as at least part of particles having an average particle size of 20 nm to 500 nm, a wax (B), and a silane compound (C) are applied to the surface of the zinc-based plating layer of a zinc-based plated steel sheet. , a phosphonic acid compound (D), a vanadium compound (E), a titanium compound (F), and water under the conditions of [I] and [II] below, and having a pH of 3.0 to 7 .0 surface treatment liquid is applied, and then heat-dried under conditions in which the temperature reached by the steel sheet is 10°C or more higher than the melting point of the wax (B) to form a surface treatment film, A method for producing a zinc-based plated steel sheet with a surface treatment film.
[I] The ratio (A _S )/(NV) of the mass (A _S ) of the solid content of the elastomer emulsion (A) containing the butadiene rubber to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0. .05 to 0.45
[II] The ratio (B _S )/(NV) of the solid content (B _S ) of the wax (B) to the total solid content (NV) of the aqueous surface treatment liquid is 0.003 to 0.050. The method for producing a zinc-based plated steel sheet with a surface treatment film according to claim 7, wherein the surface treatment liquid satisfies the following conditions [III] to [VI].
[III] The ratio (C _SiO2 )/(NV) of the mass (C _SiO2 ) of the silane compound (C) in terms of SiO ₂ to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.20. ~0.50
[IV] The ratio (D _P )/(NV) of the P-converted mass (D _P ) of the phosphonic acid compound (D) to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.004 to 0.080
[V] The ratio (E _V )/(NV) of the V-equivalent mass (E _V ) of the vanadium compound (E) to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.001 to 0. .020
[VI] The ratio (F _Ti )/(NV) of the Ti-equivalent mass (F _Ti ) of the titanium compound (F) to the mass (NV) of the total solid content of the aqueous surface treatment liquid is 0.001 to 0. .020 The method for producing a zinc-based plated steel sheet with a surface treatment film according to claim 7 or 8, wherein the vanadium compound (E) is a vanadyl compound. The method for producing a zinc-based plated steel sheet with a surface treatment film according to any one of claims 7 to 9, wherein said elastomer emulsion (A) further contains urethane rubber or polyurethane-based thermoplastic elastomer. At least one silane coupling, wherein the silane compound (C) has a tetraalkoxysilane and/or at least one reactive functional group selected from active hydrogen-containing amino groups, epoxy groups, mercapto groups and methacryloxy groups. The method for producing a zinc-based plated steel sheet with a surface treatment film according to any one of claims 7 to 10, which is an agent.

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