JPH09228074A - Surface treated steel sheet excellent in fingerprint resistance and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a surface treated steel sheet good in fingerprint resistance, in a surface treated steel sheet in which at least one side is provided with a covering layer for improving fingerprint resistance, by prescribing the total reflectivity of the covering face and the total reflectivity of the original sheet before surface treatment by an specified inequality. SOLUTION: For improving the fingerprint resistance of a steel sheet, at least one side thereof is provided with a covering layer composed of an organic resin film of polyolefine series such as polyethylene to produce a surface treated steel sheet. At this time, the covering layer is formed so as to satisfy the inequality of R1 <=0.80R, in the case the total reflectivity of the covering face in the surface treated steel sheet is defined as R1 and the total reflectivity of the original sheet before the surface treatment is defind as R0 . Thus, the surface treated steel sheet good in fingerprint resistance even in the case the surface treated covering layer does not perfectly cover the original sheet and small in the change of appearance even in the case fingerprints adhere thereto can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-treated steel sheet which can be applied to outer panels such as automobiles, household electric appliances, steel furniture, building materials, etc., and more particularly, particularly in processing or assembling. The present invention relates to a surface-treated steel sheet having excellent fingerprint resistance in which traces of fingerprints are not noticeable even when touched with bare hands. INDUSTRIAL APPLICABILITY The steel sheet of the present invention can be applied to a chromate-treated steel sheet having a chromate coating layer formed thereon and a steel sheet having a coating layer containing a silicate and / or an organic resin formed thereon, VTR, audio, computer, copying machine parts. It is particularly suitably used for parts such as chassis etc. that do not like to attach fingerprints in the assembly process after processing, parts for which processing such as deep drawing is performed, and the like.

[0002]

2. Description of the Related Art Conventionally, zinc-based plated steel sheets have been widely used as outer panel materials such as automobiles, household electric appliances, steel sheet furniture, and building materials. Since these zinc-based plated steel sheets are insufficient in corrosion resistance and paintability as they are, they are often subjected to chromate treatment or phosphate treatment, and when higher corrosion resistance and designability are required, Coating is performed by a method such as spraying, electrodeposition or powder coating. These untreated zinc-based plated steel sheets and treated zinc-based plated steel sheets may be assembled into unfinished finished products after processing, at which time the operator touches them during the assembly process. Fingerprints (traces of secretions from fingers) adhere,
There was a problem that the appearance was significantly impaired. Further, even when the product is commercialized on another line after coating, the value of the product before coating becomes low, or the fingerprint removal work is required, which results in high cost.

Further, even after the working process, scratches such as scratches may occur on the surface of the steel plate due to contact with the table during transportation of parts, or rubbing between the die and the steel plate during simple bending. Product appearance and coating performance are impaired, resulting in reduced commercial value. In particular, when the above steel sheet is subjected to severe processing such as deep drawing, the steel sheet surface of the sliding portion is markedly damaged, so that the product appearance and coating performance are further impaired.

Therefore, the improvement of the appearance deterioration due to the adhesion of fingerprints, and further the improvement of the lubricity for preventing the deterioration of the product appearance and the film performance due to the flaws caused by the deep drawing process, especially the deep drawing property Various studies have been made for the purpose of improvement.

For example, in Japanese Examined Patent Publication No. 61-36587,
Secretions from the skin fill the fine irregularities of the zinc plating, and this part absorbs light without scattering and reflection of light, so that the part where fingerprints are attached can be seen as a dark pattern and the fingerprint is said to be In order to make it inconspicuous, it is described that the unevenness of the zinc-plated crystal may be embedded in advance to make it smooth. Then, an aqueous liquid obtained by adding colloidal silica to a carboxylated polyethylene resin has a resin adhesion amount of 0.3 to 4 g / m ² (however, chromate film 1
It is disclosed that by applying it (the total amount is 0 to 60 mg / m ² ), stains due to fingerprint adhesion are not noticeable and a coating film excellent in corrosion resistance, paint adhesion and film hardness is obtained.

Further, in JP-A-59-140050, a chromium hydrate oxide film and a resin film of an organic polymer compound (100 to 3000 mg / m ² ) are formed on a zinc-based plated steel sheet.
It is possible to obtain a zinc-based plated steel sheet having excellent corrosion resistance, paintability, and fingerprint resistance by providing the above-mentioned material. JP-A-62-124297 discloses that a zinc-based plated steel sheet has a base chromate film and a coating type chromate. A surface-treated steel sheet having excellent corrosion resistance, which is formed with a coating and an organic resin coating (0.3 to ² g / m ² ) is disclosed.

The common idea of the fingerprint resistance in the prior art is to improve the fingerprint resistance by the organic resin layer. If the organic resin layer is too thin, the fingerprint resistance is not improved. That is, it is necessary to provide an organic resin layer with a specific thickness to fill the irregularities of the plated steel sheet.

However, it has been confirmed by the present inventors that even if the fine irregularities of zinc crystals on the plated steel sheet are previously filled with a resin film layer and smoothed, fingerprints are attached. This is because the level of roughness of the galvanized steel sheet itself is larger than the fine irregularities of the zinc crystal, so the irregularities of the galvanized steel sheet will not be filled unless the resin coating amount is increased and the resin film is made considerably thick. It is thought that this is due to a matter.
Therefore, it is considered that the organic resin may be simply applied thickly, but when the entire surface of the galvanized steel sheet is covered with the resin film, the electric insulation of the organic resin layer causes the VTR, audio, computer of household electric appliances. The grounding performance required for parts, cassette chassis, etc. is extremely deteriorated, and noises are newly generated due to accumulation of static electricity.

Further, sheath welding, projection welding, spot welding, etc. are performed depending on the parts, but at that time, there are problems such as sparks and explosion noise due to the resistance of the resin film, and shortening of the life of the welding electrode. Occurs.

On the other hand, as a material required to have deep drawability, JP-A-58-153785 and JP-A-58-1 are known.
Although an organic film-treated steel sheet is proposed in Japanese Patent No. 77476, all of them have the above-mentioned problem of earthing property.
Further, in order to solve the problem of earthing property, Japanese Patent Laid-Open No. 6-57
Japanese Patent Application Laid-Open No. 57-5744 discloses a film composed of an inorganic polymer compound, a solid lubricant and an aqueous resin.
Japanese Patent Laid-Open No. 2 (1993) proposes an inorganic polymerized coated steel sheet. The steel sheets disclosed in these publications improve the grounding property and the scratch resistance during deep drawing, but since both use an inorganic polymerized coated steel sheet, the treatment solution is applied to the steel sheet. There are problems such as cissing during application, black spot rust and white rust due to high water permeability of the coating, or deterioration of adhesion of the coating when applied. Occurs.

[0011]

Therefore, in the present invention, an organic resin film is simply provided as a layer to which fingerprints are hard to adhere.
We decided to investigate further from the viewpoint that fingerprints are difficult to attach and if they do not stand out as stains, it will not be a problem, and the surface treatment film does not completely cover the original plate. Provides a surface-treated steel sheet with unique characteristics that it has good fingerprint resistance, and its traces are not noticeable because the appearance change after fingerprints are attached is small, regardless of the surface roughness of the original plate. This is an issue. Furthermore, in addition to the fingerprint resistance described above, a surface-treated steel sheet having weldability such as earthing property, seam weldability, projection weldability, spot weldability, and also deep drawing workability, and the steel sheet efficiently. It is an object to provide a method that can be manufactured.

[0012]

In the surface-treated steel sheet of the present invention having excellent fingerprint resistance, which is capable of solving the above-mentioned problems, a coating layer for improving fingerprint resistance is provided on at least one surface. In the surface-treated steel sheet, the total reflectance R ₁ of the coated surface of the surface-treated steel sheet and the total reflectance R of the original sheet before the surface treatment
₀ has a gist when ₀ satisfies the following relational expression (1). R ₁ ≦ 0.80 R ₀ (1) Here, R ₀ : Total reflectance of original plate R ₁ : Total reflectance of surface-treated steel plate Further, in the present invention, as an evaluation criterion capable of clearly expressing fingerprint resistance. It is preferable that the total reflectance R ₂ of the coated surface when the artificial fingerprint liquid consisting of a saturated solution of white petrolatum-acetone at 50 ° C. is coated on the coated surface satisfies the following relational expression (2). R ₂ ≧ 0.90 R ₁ (2) where R ₁ : total reflectance of the surface-treated steel sheet R ₂ : total reflectance after application of the artificial fingerprint liquid

The "original plate before surface treatment" in the surface-treated steel sheet of the present invention is produced by a manufacturing method such as an electro-pure galvanized steel sheet, a hot dipping method, an electroplating method, or a vapor deposition plating method. Zinc or zinc alloy plated steel sheet (Zn-Ni plating, Zn-Fe plating, Zn-C
r-plating), and further, a zinc-based plated steel sheet that has been subjected to chemical conversion treatment such as phosphate treatment or chromate treatment.

The surface-treated steel sheet of the present invention is specifically a steel sheet whose coating layer for improving fingerprint resistance is substantially made of organic resin (first surface-treated steel sheet of the present invention), A steel sheet comprising a silicate (the second surface-treated steel sheet of the present invention), an alkali metal silicate, or an alkali metal silicate and a silicic acid colloid, and further an organic resin and a solid lubricant, The alkali metal silicate is lithium silicate, and the atomic ratio of Li to Si in the coating layer: Li / Si is 0.2 to 0.6, and the content of the organic resin is 0.5 to 10 weight. %, Solid lubricant content 0.2
5 to 2% by weight of steel sheet (third surface-treated steel sheet of the present invention), steel sheet comprising a chromate coating layer (fourth aspect of the present invention)
Surface-treated steel sheet). Of these, the third surface-treated steel sheet of the present invention comprising the above-mentioned coating layer has an inorganic layer such as a silicate and an organic layer such as an organic resin coated on the original sheet before surface treatment. It can be said that it is an organic composite film-treated steel sheet, and this steel sheet is excellent in corrosion resistance, deep drawability, paintability, and groundability in addition to fingerprint resistance. Further, the fourth surface-treated steel sheet of the present invention comprising the above coating layer can be said to be a chromate-treated steel sheet because the chromate film is coated on the original plate before the surface treatment, and in addition to fingerprint resistance It has excellent corrosion resistance, paintability, and groundability.

In the first surface-treated steel sheet, the volume of the portion coated with the coating layer is 80% or more and less than 100% of the volume of the recesses on the surface of the original sheet, and the surface area of the coated portion is 70% or more and less than 100% of the total surface area of the surface-treated steel sheet after coating, in the second or third surface-treated steel sheet, the surface area of the portion covered by the coating layer is 70% or more and less than 100% of the total surface area, in the fourth surface-treated steel sheet, the surface area of the portion covered by the coating layer is 80% or more and less than 100% of the total surface area of the surface-treated steel sheet after coating. Some have electrical conductivity and can exhibit good fingerprint resistance.

Furthermore, in the above-mentioned third surface-treated steel sheet, the total content of Na and / or K present as impurities in the coating layer is suppressed to 1.0% by weight or less, or the amount of coating layer attached is reduced. , The Si weight is controlled to 0.025 to 0.5 g / m ^2, and the particle size of the solid lubricant contained in the coating layer is adjusted to 0.10 to 1 μm. Incorporating a coupling agent in an amount of 1.0 to 100% by weight; or, in the fourth surface-treated steel sheet, the amount of the chromate film deposited is 10 to 250 mg in terms of metal Cr.
/ M ² or the amount of the inorganic colloid compound in the chromate treatment liquid is 1.0 to 10 with respect to a chromic acid conversion value of 1,
Phosphoric acid compound, 0.05 to chromic acid equivalent value 1 ~
By adjusting 0.5 and the silane coupling agent to 0.5 to 5 with respect to the chromic acid conversion value of 1, it is possible to further improve fingerprint resistance, corrosion resistance, paintability, weldability and the like.

The fourth method for producing a chromate-treated steel sheet is as follows. Chromium reduction rate: Cr ³⁺ / (Cr ³⁺ + C
mainly composed of chromic acid having r ⁶⁺ of 0.10 to 0.5,
Further, the gist is that a chromate treatment liquid containing an inorganic colloid compound, a phosphoric acid compound, and a silane coupling agent is applied to the surface of the original plate and dried.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION In the surface-treated steel sheet of the present invention, the total reflectance R ₁ of the coated surface of the surface-treated steel sheet and the total reflectance R ₀ of the original sheet before the surface treatment satisfy the above relational expression (1). It has the greatest feature where it does. What this means is, in short, the original plate, in the surface-treated steel sheet consisting of the coating layer provided on at least one surface of the original plate for improving the fingerprint resistance, the total reflectance of the coating layer side after the surface treatment, This means that the total reflectance of the original plate is 80% or less.

Here, "total reflectance" means JIS-K71.
It is one of the physical properties of light defined by 05 etc., and its definition is the ratio of the amount of light in all directions reflected by the object to the amount of light incident on the object. The total reflectance can be measured by, for example, a color difference meter manufactured by Nippon Denshoku Co., Ltd. or a visible ultraviolet spectrophotometer manufactured by Shimadzu Corporation, and a method of collecting light reflected from a test object using an integrating sphere. it can.

As a result of a study conducted by the present inventors, it was found that the traces of the fingerprints are conspicuous as stains because the reflectance of the traces of the fingerprints is low. If the above expression (1) is satisfied, even if a fingerprint is attached, the total reflectance of the portion without the fingerprint is low, so the difference in reflectance between the portion without the fingerprint and the portion with the fingerprint attached. Is small, and as a result, it is clear that the traces of fingerprints are inconspicuous on the appearance, and the above requirements are defined as essential requirements. If the total reflectance of the coating layer exceeds 80% of the total reflectance of the original plate, there is a large difference in reflectance between the part where fingerprints are attached and the part where fingerprints are not attached, so the traces of fingerprints can be clearly seen. It is not preferable.

The surface-treated steel sheet of the present invention has such a characteristic that fingerprints are unlikely to adhere, and that the fingerprints are inconspicuous even if fingerprints adhere. As an evaluation criterion capable of clearly expressing such a unique fingerprint resistance, the total reflectance of the coated surface when an artificial fingerprint liquid consisting of a white vaseline-acetone saturated solution at 50 ° C. is applied to a surface-treated steel sheet is The requirement to satisfy the above relational expression (2) was set according to the configuration of the steel sheet.

The above formula (2) describes the essence of the property of being excellent in fingerprint resistance, and white petrolatum at 50 ° C.
When a fixed amount of artificial fingerprint solution (fingerprint simulation solution) consisting of acetone saturated solution is applied, the total reflectance of light passing through the fingerprint simulation adhesion material and the coating layer is relative to the total reflectance before the fingerprint simulation solution is applied. If it is 90% or more, the surface-treated steel sheet provided with this coating layer has a small difference in reflectance between a portion without fingerprints attached and a portion with fingerprints attached, and even if fingerprints are attached, it is visually recognized. Instead, it shows good fingerprint resistance.

The artificial fingerprint solution used here is an acetone saturated solution of white petrolatum at 50 ° C. When a surface-treated steel sheet is immersed in this saturated solution for 1 minute, the fingerprint imitation adhered to the steel sheet shows a change in appearance close to an actual fingerprint. Therefore, this method is a test method for evaluating fingerprint resistance. The above requirement in combination with the reflectance is a requirement set in the present invention in order to evaluate the characteristic of the present invention that “the fingerprint is not conspicuous even if it is attached”. The liquid composition of the artificial fingerprint liquid, the liquid temperature,
The evaluation test conditions such as the immersion time should be recognized as one condition used for comparing the fingerprint resistance, and the requirement set by the above relational expression (2) is the surface treatment included in the present invention. Among the steel sheets, the steel sheet having the best fingerprint resistance shows that this requirement is satisfied.

As described above, the surface-treated steel sheet of the present invention makes the traces of fingerprints inconspicuous by controlling the relationship between the reflectance of the original plate and the reflectance of the surface-treated steel sheet within a specific range, and as a result, The technical idea exists in an attempt to improve fingerprint resistance. Hereinafter, the surface-treated steel sheet to which this technical idea can be applied will be specifically described in detail.

In the first surface-treated steel sheet of the present invention, a coating layer consisting essentially of an organic resin is selected in order to satisfy the above requirements for reflectance. The total reflectance after providing a film made of an organic resin as the coating layer is 8% of that of the original plate.
It is considered that these films have a refractive index similar to that of fingerprints, which is 0% or less (regular requirement of reflectance described later).

The type of resin constituting the organic resin film is not particularly limited, and examples thereof include polyolefin type resins such as polyethylene, polyurethane type, polyester type, epoxy type and acrylic type resins, and one or two of these are used. Mixtures of one or more can be used. The state of the coating liquid when forming the resin film, organic solvent solution system, aqueous solution system,
Although not particularly limited, such as an aqueous dispersion system and a solventless system, an aqueous dispersion (emulsion) is used when two or more resins are mixed or when a silicate is further mixed with the resin.
Systems are preferred.

In preparing the coating solution, in order to enhance the performance of the coating layer, a pigment, a partial cross-linking agent, a diluting solvent, an anti-skinning agent and a leveling agent are used within a range that does not significantly change the appearance and color tone of the surface-treated steel sheet of the present invention. Agent, defoamer, penetrant,
Various additives such as film forming aids, thickeners and lubricants, and finely divided silica, colloidal silica, silane coupling agents and the like for improving adhesion and corrosion resistance can be appropriately added. Even if these additives are added, if the main component is an organic resin, the coating layer is “substantially made of an organic resin”.

Further, in the present invention, the compatibility between ensuring the electric conductivity and good anti-fingerprint property was examined, and when the volume of the covered portion is 80% or more and less than 100% with respect to the volume of the concave portion existing on the surface of the original plate. It was found that if the surface area of the coated portion is 70% or more and less than 100% of the total surface area of the surface-treated steel sheet after coating, good fingerprint resistance can be obtained while ensuring the energizing point. .

That is, when the surface of the original plate is completely covered with the coating layer, the fingerprint resistance is of course improved, but the electrical conductivity is lost. However, by providing the coating layer so as to satisfy the above-mentioned requirements of the present invention, the uncoated portion becomes the current-carrying point because the original plate is exposed, and electrical conductivity can be secured. Moreover, since the total reflectance after coating is 80% or less with respect to the original plate, fingerprints are not noticeable.

FIG. 1 shows a sectional view for explaining the volume of the recess and the volume covered. The volume of the concave portion on the surface of the original plate is calculated by using a three-dimensional roughness meter and the volume of one concave portion is calculated as 10
It is a value obtained by averaging the results of the individual concave portions. When a laser microscope is used as a three-dimensional roughness meter, it is possible to obtain the roughness of minute irregularities on the surface of the original plate as compared with a stylus roughness meter, and the laser can be used even after being coated with a coating layer. When it is possible to reach the original plate through the coating, it is also possible to determine the roughness of the original plate after forming the coating layer. A specific measuring method using a laser microscope is to first measure the two-dimensional roughness in the XZ direction with respect to the sample surface, and then move the laser scanning step by submicron in the Y direction to the three-dimensional (X -Y-Z) A roughness curve is obtained, and the volume of the depression of the original plate is obtained by integrating the depression area of the two-dimensional roughness curve with the lowest point of the obtained three-dimensional roughness curve as a reference. Follow the procedure.

The surface coverage is a ratio of the coating layer film on the surface of the surface-treated steel sheet, and can be obtained by using an SEM and an image analyzer. That is, an image of a minute portion of the surface-treated steel sheet may be photographed using an SEM, and this SEM observation photograph may be applied to an image analyzer to obtain the areas of the covered portion and the uncoated portion. For reference, FIG. 2 shows a schematic view of the coated surface portion. However, when the boundary between the coated and uncoated portions is unclear in the photograph taken with the SEM, image analysis is difficult, so the component C and / or Si element of the coating layer E
The surface analysis by PMA is performed to clarify the boundary between the covered portion and the non-covered portion, and then the coverage is obtained by applying the image analysis device. The coverage is 1 × 10 ^-6 m ² per unit area
The average value is calculated by selecting 10 arbitrary arbitrary minute parts and measuring. It should be noted that although EPMA can also photograph a minute portion, SEM is used in the present invention because the resolution of SEM is superior.

In the present invention, "the volume of the coated portion is 80% or more with respect to the volume of the concave portion existing on the surface of the original plate 10"
The surface area of the coated portion is 70% or more and less than 100% of the total surface area of the surface-treated steel sheet after coating ", which is a surface having excellent fingerprint resistance and electrical conductivity. This is important when manufacturing a treated steel sheet, that is, a surface-treated steel sheet whose total reflectance after coating is 80% or less of the original sheet. If a coating layer is provided so as to satisfy the above requirements, fingerprints will not adhere. This shows that a surface-treated steel sheet that is inconspicuous and has electrical conductivity can be obtained. Such a surface-treated steel sheet can be preferably applied in a field such as a member such as a VTR chassis, which is required to have anti-fingerprint property and earth property.

Next, a method of manufacturing the above-mentioned surface-treated steel sheet according to the present invention will be described. The surface-treated steel sheet can be manufactured by applying a coating solution containing an organic resin as a main component to the surface of the original plate by an arbitrary coating method and drying the coating solution. There is no limitation on the method of applying the coating liquid. For example, a roll coater may be used on the surface of the long strip of the original plate that has been cleaned or pre-treated (for example, phosphate treatment or chromate treatment). A known coating means such as a coating method, a spray method, or a curtain flow coater method may be adopted.

Considering the uniformity of the coating thickness, the processing cost, the coating efficiency, etc., the most practically preferable method is the coating method using a roll coater. The coating layer can be formed on only one side or both sides of the original plate.

In the second surface-treated steel sheet of the present invention, a coating layer consisting essentially of silicate is selected in order to satisfy the above-mentioned requirements for reflectance. The total reflectance after providing a film made of silicate as a coating layer is 8% of that of the original plate.
It is considered that these films have a refractive index similar to that of fingerprints, which is 0% or less (regular requirement of reflectance described later).

Examples of the type of silicate include lithium silicate, sodium silicate, potassium silicate, and the like.
A single kind or a mixture of two or more kinds thereof can be used. Since these silicates are water-soluble, the coating layer can be easily formed on the original plate by using various coating methods in an aqueous solution state.

In preparing the coating solution, in order to enhance the performance of the coating layer, a pigment, a partial cross-linking agent, a diluting solvent, an anti-skinning agent and a leveling agent are used within a range that does not significantly change the appearance and color tone of the surface-treated steel sheet of the present invention. Agent, defoamer, penetrant,
Various additives such as film forming aids, thickeners and lubricants, and finely divided silica, colloidal silica, silane coupling agents and the like for improving adhesion and corrosion resistance can be appropriately added. Even if these additives are added, if the main component is silicate, the coating layer is “consisting essentially of silicate”.

In the present invention, "the surface area of the coated portion is 70% or more of the total surface area of the surface-treated steel sheet after coating and 100 or more.
The requirement "is less than%" is for producing a surface-treated steel sheet having excellent fingerprint resistance and electrical conductivity, that is, a surface-treated steel sheet whose total reflectance after coating is 80% or less of the original sheet. This is important, and it shows that if a coating layer is provided so as to satisfy the above requirements, a surface-treated steel sheet with less noticeable fingerprint adhesion and electrical conductivity can be obtained. Such a surface-treated steel sheet can be preferably applied in a field such as a member such as a VTR chassis, which is required to have anti-fingerprint property and earth property.

Next, a method for manufacturing the above-mentioned surface-treated steel sheet according to the present invention will be described. The surface-treated steel sheet can be produced by applying a coating liquid containing a coating liquid containing a coating layer constituent component as a main component to the surface of the original plate by an arbitrary coating method and drying the coating liquid. There is no limitation on the coating method of the coating liquid, and for example, the same method as that of the first surface-treated steel sheet of the present invention can be adopted. Considering the uniformity of the film thickness, the processing cost, the coating efficiency, etc., the most practically preferable method is the coating method using a roll coater. The coating layer can be formed on only one side or both sides of the original plate.

The third surface-treated steel sheet (inorganic / organic composite film-treated steel sheet) of the present invention has an alkali metal silicate salt, or an alkali metal silicate salt and a silicic acid colloid, in order to satisfy the above requirements for reflectance. Which further comprises an organic resin and a solid lubricant, wherein the alkali metal silicate is lithium silicate, and the atomic ratio of Li to Si in the film (Li / Si): 0.2. ~ 0.6, content of organic resin: 0.5 to 10% by weight, content of solid lubricant: 0.2
An inorganic / organic composite film consisting of 5 to 2% by weight is selected. The total reflectance after providing such an inorganic / organic composite coating as a coating layer is 80% or less of the reflectance of the original plate (the above-mentioned requirement for the reflectance) because these coatings are
It is considered that it has a refractive index similar to that of a fingerprint. A steel sheet satisfying such requirements is excellent in deep drawing workability, corrosion resistance, paintability, and groundability in addition to good deep drawing workability. Hereinafter, the reasons for the above definition will be sequentially described.

First, Li and Si in the glassy film
The atomic ratio (Li / Si) of is preferably 0.2 to 0.6.
If it is less than 0.2, the film-forming property of the film is deteriorated, and minute cracks are generated in the film, so that the film-forming property of the film is deteriorated, and the film having excellent adhesion cannot be formed. In addition to the remarkable deterioration of the properties, the corrosion resistance and the paintability also deteriorate. On the other hand, L
When i / Si exceeds 0.6, the adhesion of the coating film after coating is deteriorated, and the refractive index of the coating is reduced, so that the total reflectance with respect to the original plate tends to increase. The requirements cannot be satisfied, and the fingerprint resistance deteriorates.

Further, the glassy film may contain sodium silicate and / or potassium silicate as impurities. Compared with lithium silicate, these have poorer wettability with the steel plate, so when applying the treatment liquid to form the inorganic-organic composite film, cissing etc. occurs during the application of the treatment liquid and a uniform film is obtained. However, since the film has defects, fingerprint resistance, deep drawing workability, corrosion resistance and the like deteriorate. Therefore, in the present invention, Na contained in the film is
It is preferable to suppress the total content of and / or K to 1.0% by weight or less. More preferably 0.8% by weight
It suppresses to the following.

Further, the organic resin is added for the purpose of improving the film forming property of the film and the corrosion resistance. If the content of the organic resin is less than 0.5% by weight, the above-mentioned action cannot be effectively exhibited. More preferably, 4 wt% or more is added. On the other hand, if it exceeds 10% by weight, the resin peels off on the sliding surface to cause a blackening phenomenon during deep drawing,
Poor appearance after processing. It is more preferably 8% by weight or less.

The organic resin used in the present invention is not particularly limited, but urethane resins, acrylic resins, polyethylene resins, polystyrene resins and polyester resins are preferred.

The solid lubricant improves lubricity between the die and the steel sheet during deep drawing by imparting lubricity to the coating, and prevents the inorganic / organic composite coating from being scratched by the die. It is added to reduce the damage of the coating. When the addition amount of the solid lubricant is less than 0.25% by weight, the ratio of the solid lubricant to the surface area of the coating becomes small, and the effect of improving lubricity cannot be sufficiently obtained. More preferably 0.4% by weight
The above is added. On the other hand, if it exceeds 2% by weight, the corrosion resistance and paintability of the film deteriorate. It is more preferably at most 1% by weight.

The particle size of the solid lubricant added is 0.1.
It is preferably 0 to 1 μm. Particle size is 0.10 μm
If it is smaller than the above range, the lubricant is buried in the film, and the lubricating performance improving effect cannot be sufficiently obtained. More preferably, 0.
It is 4 μm or more. On the other hand, when it exceeds 1 μm, the uniform dispersibility of the solid lubricant in the treatment liquid and the liquid stability deteriorate,
It becomes difficult to apply it uniformly to the steel sheet. More preferably, it is 0.8 μm or less.

The type of the solid lubricant is not particularly limited,
Among the commonly used solid lubricants such as polyethylene wax, polyethylene oxide wax, polypropylene oxide wax, carnauba wax, paraffin wax, montan wax, rice wax, Teflon wax, molybdenum disulfide, carbon disulfide and graphite, 1
One kind or two or more kinds can be arbitrarily selected. Considering the lubricating performance and the dispersion state in the treatment liquid, it is recommended to add the above-mentioned wax type lubricant to the coating liquid in the state of water dispersion type wax.

The amount of the inorganic / organic composite coating deposited is preferably in the range of 0.025 to 0.5 g / m ² in terms of Si weight. If the amount of coating adhered is less than 0.025 g / m ^2, the thickness of the formed coating will be too thin to satisfy the requirement of the above formula (1), and the adhered fingerprints can be easily visually observed. In addition to being conspicuous, deep drawing workability is significantly deteriorated because a vitreous film that is tough and hard enough to withstand die sliding cannot be obtained. More preferable adhesion amount is 0.0
It is 5 g / m ² or more. On the other hand, although the corrosion resistance improves with the increase in the amount of adhesion and does not adversely affect the regulation of the above formula (1), when it exceeds 0.5 g / m ² , the film resistance value increases and the earthing property deteriorates. Resulting in. A more preferable adhesion amount is 0.4 g / m ² or less.

If a silane coupling agent is contained in the coating layer of the steel sheet of the present invention, not only the adhesiveness after coating (primary adhesiveness) but also the coating adhesion after immersion in boiling water after coating. It is also possible to improve the property (secondary adhesion).
Although the mechanism for improving coating film adhesion of such a silane coupling agent has not been completely clarified,
Alcohol group and silanol group are generated by hydrolysis of the alkoxy group bonded to silicon in an aqueous solution,
It is presumed that the generated silanol groups strengthen the binding force with the coating film after coating.

The silane coupling agent is generally an alkoxy group such as a methoxy group or an ethoxy group; an alkyl group such as a methyl group or an ethyl group; a functional group such as a vinyl group, a glycidoxy group, a methacryloxy group, an amino group or a mercapto group. Is bonded to Si via an alkylene group or not, and the silane coupling agent used in the steel sheet of the present invention is a silane coupling agent represented by the above formula (3) or (4). Is recommended, and one or more of these can be used in combination.

The alkoxy group bonded to silicon in the silane coupling agent is hydrolyzable because the effect of improving the coating adhesion is presumed to be the silanol group produced by the hydrolysis of the alkoxy group. It is preferably a lower alkoxy group such as a methoxy group or an ethoxy group. Of these, a methoxy group having a low boiling point is more preferable in view of the fact that the alcohol produced after hydrolysis adversely affects the film-forming property of the film. Specific examples include β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropylmethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, and γ-aminopropyltriethoxysilane. .

As described above, the present invention does not limit the type of the silane coupling agent to be contained, but from the viewpoint of dispersibility and compatibility in an aqueous solution, the above formula (5) or ( It is preferable to use a silane coupling agent having a glycidoxy group at the terminal as shown in formula (6), and these can be used alone or in combination of two or more. Specific examples include γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropylmethyldimethoxysilane.

However, when the content of the silane coupling agent is less than 1.0%, the effect of improving the adhesion of the coating film is insufficient, and the adhesion of the coating film after coating, especially the secondary adhesion If a steel sheet having excellent properties is not obtained, and if it exceeds 10% on the other hand, the effect of improving coating film adhesion, especially secondary adhesion, is saturated, and the formed film becomes brittle and adversely affects workability. Therefore, the content of the silane coupling agent is recommended to be 1.0 to 10%.

As described above, the silane coupling agent has a remarkable effect on the improvement of the secondary adhesion of the coating film after coating, but the addition of the silane coupling agent does not give a sufficient effect. For the first time, lithium silicate is selected as the alkali metal silicate, and the Li / Si ratio in the film is controlled, and the contents of Na and K contained in the alkali metal silicate are optimized. It goes without saying that a surface-treated metal plate having excellent primary and secondary adhesion after coating can be obtained.

Such an inorganic / organic composite film-treated steel sheet of the present invention has the characteristic that fingerprints are hard to attach and the unique characteristic that even if fingerprints are attached, it is inconspicuous. Since it forms a harder and tougher film, it has excellent workability, especially deep drawing workability, and also has contradictory properties such as corrosion resistance, paintability, and groundability.

In the present invention, "the surface area of the portion coated with the above-mentioned coating layer (inorganic / organic composite coating) is 70% or more and less than 100% of the total surface area of the coated inorganic / organic composite coated steel sheet. The requirement is that the steel plate is excellent in fingerprint resistance and deep drawing workability, and also has good corrosion resistance, paintability, groundability, and weldability, that is,
Total reflectance after coating with inorganic / organic composite film is 8 against the original plate
It is important when manufacturing an inorganic / organic composite film-treated steel sheet with a content of 0% or less, and if an inorganic / organic composite film that satisfies the above requirements is formed, the adhered fingerprints will be inconspicuous and deep drawability will be improved. This shows that an inorganic / organic composite film-treated steel sheet that is excellent and can satisfy contradictory properties such as corrosion resistance, paintability, and earthing property can be obtained. Such an inorganic / organic composite coated steel sheet is, for example, a VTR.
It can be preferably applied in the field of home electric appliances such as chassis for audio and audio, and computer-related members required to have a grounding property.

Next, a method of manufacturing the above-mentioned inorganic / organic composite coating-treated steel sheet according to the present invention will be described. In the present invention, lithium silicate or a mixture of lithium silicate and silicic acid colloid is applied to the surface of the original plate with an inorganic / organic composite coating solution containing the above-mentioned organic resin and solid lubricant, and then heated to a predetermined temperature. Then, by drying, it is possible to form a glassy film made of a strong dry gel of fine silica particles.

Lithium silicate is commercially available as lithium silicate, and commercially available products such as lithium silicate 35, lithium silicate 45 and lithium silicate 75 [manufactured by Nissan Kagaku Co., Ltd.] can be preferably used.

Also, silicic acid colloids are commercially available as colloidal silica and colloidal sol. Snowtex 30, Snowtex 40, Snowtex UP, Snowtex N, Snowtex XS, Snowtex K, PC-500 [NISSAN CHEMICAL ( A commercial product such as a product manufactured by K.K. can be preferably used.

The inorganic / organic composite film obtained by applying and drying such an inorganic / organic composite film treatment liquid on the surface of the original plate is
In addition to satisfying the requirement of the above formula (1), the inorganic-organic composite film-treated steel sheet has good deep drawability, corrosion resistance, paintability, and earthing property in addition to excellent fingerprint resistance.

In the fourth surface-treated steel sheet (chromate-treated steel sheet) of the present invention, a coating layer made of a chromate film is selected in order to satisfy the above reflectance requirement, and the chromate film is provided as the coating layer. It is considered that the total reflectance after the coating becomes 80% or less of the reflectance of the original plate (the above-mentioned requirement for the reflectance) because the film has a refractive index similar to that of a fingerprint.

The amount of the chromate film deposited is preferably 10 to 250 mg / m ^{2 in} terms of metallic Cr. 1 coating amount
When the amount is less than 0 mg / m ^2, the total reflectance R ₁ of the chromate-treated steel sheet satisfying the above formula (1) cannot be obtained, and the attached fingerprints are conspicuous, and the desired excellent fingerprint resistance is obtained. In addition, the corrosion resistance and paintability also deteriorate significantly.
It is more preferably 15 mg / m ² or more. On the other hand, when the amount of adhesion exceeds 250 mg / m ² , the reflectance R ₁ satisfying the above formula (1) is obtained, so that the effect of improving corrosion resistance and paintability is remarkably observed, but the amount of film adhesion increases. Along with this, the content of the inorganic colloid compound (described later) also increases, so that the film resistance increases and the grounding property and the weldability deteriorate significantly. More preferably 150 m
g / m ² or less.

In the above-described steel sheet of the present invention, the requirement that "the surface area of the portion coated with the chromate film is 80% or more and less than 100% of the total surface area of the chromate-treated steel sheet after coating" is excellent in fingerprint resistance. At the same time, it is important in producing a chromate-treated steel sheet having improved corrosion resistance, paintability, groundability and weldability, that is, a chromate-treated steel sheet whose total reflectance after coating with a chromate film is 80% or less of the original sheet. Yes, if a chromate treatment film is formed to satisfy the above requirements, the adhered fingerprints will not be noticeable, and the chromate treatment can satisfy the contradictory characteristics such as corrosion resistance, paintability, groundability, and weldability. This shows that a steel sheet can be obtained. Such a chromate-treated steel sheet can be preferably applied in the field of home electric appliances such as chassis for VTRs and audios, computer-related members that are required to have a grounding property.

Next, a method for manufacturing the above-described chromate-treated steel sheet of the present invention will be described. In the present invention, in order to satisfy the above reflectance requirements, the reduction rate of chromium: Cr ⁺³
It is necessary to use a chromate treatment liquid containing chromic acid whose // (Cr ³⁺ + Cr ⁶⁺ ) is 0.10 to 0.5 as a main component and further containing an inorganic colloid compound, a phosphoric acid compound and a silane coupling agent. is there.

The reduction ratio of chromium described above is 0.10 to 0.
The chromic acid solution of No. 5 is an aqueous solution of chromic anhydride or a reduced chromic acid solution having a reduction rate of 0.5, and the reduction rate is adjusted by reducing with a commonly used inorganic reducing agent or organic reducing agent. can do. When the reduction rate of chromium is less than 0.10, the color tone of the formed chromate film is yellow due to Cr ⁺⁶ , and the fingerprints attached tend to be inconspicuous, but the Cr ⁺⁶ in the film in a wet environment tends to be inconspicuous. Absorbs and dissolves water and locally corrodes the zinc plating, so that fine green spot-like stains occur. On the other hand, when the reduction rate of chromium exceeds 0.5, the stability of the chromate treatment agent is significantly deteriorated, and it becomes difficult to uniformly apply it to the steel sheet, and the requirement of the above formula (1) cannot be obtained.
It is more preferably 0.4 or less.

In addition, it is necessary to add an inorganic colloidal compound to the chromate treatment liquid. This is for improving the corrosion resistance of the chromate film and for preventing the repelling (uneven coating) of the chromate treatment liquid on the steel sheet. As the inorganic colloidal compound, colloidal silica is preferable, but alumina sol, titania sol, zirconia sol and the like can also be used, and these can be used in combination. The inorganic colloid compound is preferably contained in a ratio of 1.0 to 10 with respect to a chromic acid conversion value of 1. When the content ratio of the inorganic colloid compound is less than 1.0 with respect to the chromic acid equivalent value 1, the effect of improving the corrosion resistance is not recognized, and the repellency preventing effect of the chromate treatment liquid on the steel sheet cannot be effectively exhibited. That is, when a chromate treatment liquid having poor wettability with the surface of the original plate is applied to the surface of the original plate, the surface tension causes aggregation and repellency, but if an inorganic compound is contained in the chromate treatment liquid, it will be contained in the processing liquid. It is considered that the dispersed inorganic colloidal compound can suppress aggregation due to surface tension and prevent the occurrence of cissing. It is more preferably 1.5 or more.
On the other hand, when the ratio of the inorganic colloid compound is more than 10 with respect to the chromic acid equivalent value of 1, the film forming property of the chromate film is deteriorated, the corrosion resistance is deteriorated, and the requirement of the above formula (1) cannot be obtained. .

Further, the phosphoric acid compound added to the chromate-treating solution has a function of further improving the corrosion resistance, and in order to effectively exhibit such a function, it is 0 for 1 of the chromic acid conversion value. It is preferable to add 0.05 or more. More preferably, it is 0.08 or more. On the other hand, 0.5
If it exceeds, the hygroscopicity of the chromate film increases, and the effect of improving corrosion resistance cannot be obtained. The type of the phosphoric acid compound added in the present invention is not particularly limited, and orthophosphoric acid, various condensed phosphoric acids, their ammonium salts, alkaline earth metal salts and the like are preferably used.

Further, the silane coupling agent added to the chromate-treating solution is 0.1% with respect to a chromic acid conversion value of 1.
The range of 5 to 5 is preferable. If the chromic acid equivalent value is less than 0.5, the soluble Cr ⁶⁺ in the chromate film
Elutes and causes uneven stains on the surface of the original plate,
The appearance of the chromate treated steel sheet is significantly deteriorated. It is more preferably 0.8 or more. On the other hand, if more than 5 is added to the chromic acid equivalent value, the effect of preventing soluble Cr ⁶⁺ from eluting is saturated, which is economically wasteful. As the silane coupling agent used in the steel sheet of the present invention,
In terms of its excellent effect of preventing dissolution of soluble Cr ⁶⁺ ,
It is preferable to use a silane coupling agent having a methoxy group. Specific examples include vinyltrimethoxysilane, γ- (methacryloxypropyl) trimethoxysilane, γ-glycidoxypropyltrimethoxysilane,
Examples thereof include N-β (aminoethyl) γ-aminopropyltrimethoxysilane and γ-mercaptopropyltrimethoxysilane, and these can be used alone or in combination of two or more.

A chromate film can be produced by applying the chromate treating agent having the above-mentioned composition to the surface of the original plate by an arbitrary method and drying it. still,
The method for applying the chromate treatment agent is not particularly limited, and for example, a known application method such as a roll coater method, a spray method, or a curtain flow coater method may be adopted.

The present invention will be described in more detail with reference to the following examples, but the following examples are not intended to limit the present invention, and any modification that is made without departing from the spirit of the preceding and the following will be within the technical scope of the present invention. Included in.

[0071]

EXAMPLES The evaluation methods used in the following examples are as follows. (1) Change in total reflectance before and after surface treatment Using a color difference meter manufactured by Nippon Denshoku Co., Ltd., JIS-K7105
Based on the above, the total reflectance of the test material was measured. The total reflectance at 560 nm of the standard white surface of a sample formed by molding barium sulfate powder (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) was determined as 100% standard. In order to represent the change in total reflectance before and after the surface treatment of the test material, the ratio of the total reflectance R ₁ after coating to the total reflectance R _o of the original plate was defined as the total reflectance change degree: R ₁ / R _o . In Examples 2 and 3, a galvanized steel sheet having a total reflectance of about 83% was used as the original plate, and in Examples 1 and 4 to 6, a reactive chromate-treated steel sheet having a total reflectance of about 72% was used as the original plate. I was there.

(2) Degree of change in total reflectance before and after application of artificial fingerprint liquid A part of the surface-treated steel sheet after the coating layer was cut out was cut into 50 pieces.
White vaseline at ℃ (Wako Pure Chemical Industries, Ltd. reagent first grade)
Total reflectance R ₂ after immersion in saturated acetone (Wako Pure Chemical Industries, Ltd. reagent special grade) saturated solution (artificial fingerprint liquid) for 1 minute in the same manner as in the above (1), the artificial fingerprint The change rate R ₂ / R ₁ of the total reflectance was calculated as an index showing the change in the total reflectance before and after the liquid application.

(3) Coverage of coating layer (3-1) Coverage of surface recess (volume fraction) The coverage of the surface recess is the volume of how much the coating layer covers the surface recess of the original plate. It is a fraction. First, the original plate was observed for irregularities per 1 × 10 ⁻⁶ m ² with a scanning laser microscope manufactured by Lasertec at a magnification of 392 times, and the average total volume V ₀ m ³ of the 10-point concave portions in the three-dimensional sectional curve was obtained. I asked. Since the adhesion amount Wg / m ² is obtained from the weight difference between the original plate and the surface-treated steel plate after the coating treatment, the specific gravity of the organic resin is 1.1 × 10 ⁻⁶ g / m ³ , and the specific gravity of the silicate is 2.
2 g / m ³ , the composition of the coating layer was calculated, the volume V ₁ m ³ of the coated portion was calculated, V ₁ / V ₀ was calculated, and the coverage of the surface recesses (volume fraction:%) And

(3-2) Surface Area Coverage (Area Ratio) The surface area coverage was observed with a scanning electron microscope JSM-T200 manufactured by JEOL Ltd. at a magnification of 100 times.
Further, for the unit area of 1 × 10 ^-6 m ² Carl
-By performing analysis at 10 locations using Zeiss image analyzer IBAS, 1
The area ratio per unit area of 0-point average was calculated and used as the surface area coverage.

Whether or not a coating was applied to that portion was confirmed using an electron beam microanalysis apparatus (EPMA) JXA-8621MX manufactured by JEOL Ltd. When the main component of the coating layer is silicic acid, the Si element strength is
In the case of an organic resin, the C element strength was examined for both mixed coatings, and divided into a coated portion and a non-coated portion. With EPMA, the accelerating voltage was 20 KV, and the detection levels of the elements were adjusted so that the coated portions could be represented by white dots and the uncoated portions by black dots.

(4) Anti-fingerprint property An acetone solution saturated with white petrolatum at 50 ° C. was used as an artificial fingerprint liquid, and the test material was immersed in the artificial fingerprint liquid for 1 minute. In Example 1, the change in color tone due to immersion was visually observed and evaluated according to the following criteria. <Evaluation of fingerprint resistance> Excellent: The fingerprint (artificial fingerprint liquid) is not noticeable at all. ○ Good: Fingerprints are hardly noticeable. × Inferior: Adhesion of fingerprints is noticeable. In Examples 2 to 5, changes in color tone due to immersion were measured with a color difference meter manufactured by Nippon Denshoku Co., Ltd., and ΔE was calculated based on the following calculation formula.
The value was calculated and the fingerprint resistance was evaluated.

[0077]

[Equation 1]

<Evaluation of fingerprint resistance> Excellent: ΔE = less than 1 → Fingerprint adhesion is not noticeable at all. ○ Good: ΔE = 1 to less than 1-3 → Fingerprint adhesion is hardly noticeable. × Inferior: ΔE = 3 or more → Fingerprint adhesion is noticeable.

(5) Corrosion resistance Regarding the edge-sealed test material, JIS-Z2371
The salt spray test of the flat plate was conducted according to the above. <Evaluation of Corrosion Resistance> ◎ Excellent: White rust is generated 1% at a salt spray time of 168 hours.
Below ○ Good: White rust occurred 1% after 120 hours of salt spraying
Below × Inferior: 1% of white rust occurred after 120 hours of salt spraying
that's all

(6) Paintability (primary adhesion) After bar-coating an acrylic paint under the following conditions,
The coating film adhesion was evaluated according to the following criteria. <Coating conditions> -Coating: Magicron 1000 (manufactured by Kansai Paint Co., Ltd.)-Coating film thickness: 20 ± 1 μm-Baking conditions: 160 ° C x 20 minutes <Evaluation of adhesion of coating film> -1 mm with a cutter on a 1 mm coated plate Base of 100
After the mass was put in and subjected to Erichsen extrusion molding with a height of 6 mm as it was, a tape peeling test was carried out, and the residual mass after peeling the coating film was measured and evaluated according to the following criteria. ◎ Excellent: 100% of the number of remaining coating squares ○ Good: 90% or more and less than 100% of the number of remaining coating layers × Inferior: Less than 90% of the number of remaining coating layers

(7) Coatability (Secondary Adhesion) After coating, each test piece was immersed in boiling water for 1 hour and allowed to stand at room temperature for 1 hour, after which the residual coating rate was measured by the same method as for the primary adhesion. Then, the secondary adhesion was evaluated according to the following criteria. ◎: coating film residual rate 100% ○: coating film residual rate 80% or more and less than 100% Δ: coating film residual rate 40% or more and less than 80% ×: coating film residual rate less than 40% In the following description, simply coatability When described as, it means the coating property (primary adhesion).

(8) Earthing property The surface resistance of the test material was measured with a surface resistance meter, Lorester MP, manufactured by Mitsubishi Chemical Corporation, and evaluated according to the following criteria. <Evaluation of groundability> ◎ Excellent: Surface resistance value = less than 0.5Ω ○ Good: Surface resistance value = 0.5 to less than 1.0Ω × Inferior: Surface resistance value = 1.0Ω or more

(9) Weldability Dome type (tip diameter 6 mm, 40 mmR), material: 1% C
Using an r-Cu electrode, a pressing force of 2156N (220kg
f), current 8kA, energizing time 12 cycles (60Hz)
1000 spot welding test under the conditions of
The percentage ratio of good welding points to all welding points was used as a measure of weldability. In addition, the occurrence of surface scattering (surface spark) at all hit points was visually evaluated. <Evaluation of weldability> ◎ Excellent: 100% good welding point, very little surface scattering. ○ Good: Good Welding point 95 to less than 100%, less occurrence of surface scattering. × Inferior: Good Welding point less than 95%, occurrence of surface scattering.

(10) Deep drawing workability A single press test was carried out using an 80 ton crank press to check the galling and blackening phenomenon (blackening resistance) of the sliding surface of the molded product after molding. It was visually observed and the deep drawing workability was evaluated according to the following criteria. <Evaluation of deep drawability> ◎ Excellent: No mold galling or blackening phenomenon on the sliding surface of the molded product. ○ Good: Mold galling and blackening on the sliding surface of the molded product occurred slightly. × Inferior: Mold galling and blackening phenomenon on the sliding surface of the molded product remarkably occurred.

(11) Friction coefficient Using a sliding tester, the pulling load was measured when the test was conducted at a pressing force of 46 kgf / cm ² and a pulling speed of 300 mm / min, and the dynamic friction coefficient was measured from the pulling load. . The dynamic friction coefficient was measured on both sides at the same time, and the measurement results were expressed as the average of both sides.

Example 1 In this example, the first and second surface-treated steel sheets of the present invention were examined. Table 1 for forming the coating layer
Coating liquids A to D having the compositions shown in were prepared. Among them, the steel sheet obtained by using the coating liquids B and C corresponds to the first surface-treated steel sheet of the present invention, and the steel sheet obtained by using the coating liquids A and D is the second surface-treated steel sheet of the present invention. Equivalent to.
As the silicate aqueous solution, SiO ₂ as solid content is 20
% By weight, SiO ₂ / Na ₂ O ratio of 10/1 to 4 /
An aqueous sodium silicate solution of No. 1 was used. An emulsion having a solid content of 20% by weight was used for both the polyethylene resin and the polyurethane resin.

[0087]

[Table 1]

Next, an electrogalvanized steel sheet (amount of zinc deposited:
Chromate treatment (20 g / m ² ) (Cr deposit: 20 m
g / m ² ) was performed to obtain a master plate. The total reflectance of the original plate is 8
It was 3%. The various coating liquids A to D shown in Table 1 were coated on the surface of the original plate with a roll coater while changing the amount of coating so as to have various coverages, and then transferred in a hot air drying oven to be dried. . Regarding the performance evaluation results of the various steel sheets obtained, Table 2 shows the results of the first surface-treated steel sheet of the present invention, and Table 3 shows the results of the second surface-treated steel sheet of the present invention.

[0089]

[Table 2]

From Table 2, the following can be considered. Nos. 1 to 5 and 8 to 12 are examples in which the degree of change in total reflectance after surface treatment satisfies 0.80 or less, which is the range defined by the present invention, and total reflection after application of the artificial fingerprint liquid. The rate change rate is 0.90 or more, which is the range defined by the present invention, and it is understood that the film has excellent fingerprint resistance. However,
When the coverage is 100% as in No. 5 or 12, the earth property becomes poor.

On the other hand, in Nos. 6, 7, 13, and 14,
This is a comparative example in which the degree of change in total reflectance after surface treatment exceeds 0.80, the coverage is out of the range defined by the present invention, and the degree of change in total reflectance after application of the artificial fingerprint liquid is also less than 0.90. It can be seen that the fingerprint resistance is inferior.

[0092]

[Table 3]

From Table 3, the following can be considered. Nos. 1 to 5 and 8 to 12 are examples in which the degree of change in total reflectance after surface treatment satisfies 0.80 or less, which is the range defined by the present invention, and total reflection after application of the artificial fingerprint liquid. The rate change rate is 0.90 or more, which is the range defined by the present invention, and it is understood that the film has excellent fingerprint resistance. However,
When the coverage is 100% as in No. 5 or 12, the earth property becomes poor.

On the other hand, Nos. 6, 7, 13, and 14 are
This is a comparative example in which the degree of change in total reflectance after surface treatment exceeds 0.80, the coverage is out of the range defined by the present invention, and the degree of change in total reflectance after application of the artificial fingerprint liquid is also less than 0.90. It can be seen that the fingerprint resistance is inferior.

Example 2 In this example and Example 3 described later, the fourth surface-treated steel sheet of the present invention was examined. The chromate treatment liquid shown in Table 4 was prepared for forming a coating layer. As the inorganic colloidal compound, colloidal silica “Snowtex 40” manufactured by Nissan Chemical Industries, Ltd., orthophosphoric acid as a phosphoric acid compound, and β- (produced by Shin-Etsu Chemical Co., Ltd. as a silane coupling agent). 3,4 epoxycyclohexyl) ethyltrimethoxysilane was used, respectively.
The content of the inorganic colloidal compound in the chromate treatment liquid is represented by the ratio of SiO _{2 to} chromic acid, and the content of the phosphoric acid compound in the chromate treatment liquid is represented by the ratio of H ₃ PO ₄ to chromic acid. .

Next, electrogalvanized steel having a total reflectance of about 83%.
Plated steel plate (Zinc coverage: 20 g / m ^Two ) As the original plate,
Apply the above chromate treatment liquid and apply the chromate coating layer.
Deposition amount is 5 to 300 mg / m in terms of metallic Cr^Two In the range of
After controlling so that it will dry for 1 minute at 100 ℃ in a hot air drying oven.
A test material was prepared by drying. Of the obtained test material
The performance evaluation is shown in Table 5.

[0097]

[Table 4]

[0098]

[Table 5]

From Table 5, the following can be considered. Nos. 1 to 6 are Examples in which the degree of change in total reflectance after surface treatment satisfies 0.80 or less, which is the range defined by the present invention, and the degree of change in total reflectance after application of the artificial fingerprint liquid is It is 0.90 or more, which is the range specified in the present invention, and it is understood that the film has excellent fingerprint resistance.

On the other hand, in No. 7, since the amount of the chromate coating layer deposited was small, the degree of change in total reflectance after the surface treatment exceeded 0.80, indicating that fingerprint resistance was poor. In No. 8, the degree of change in total reflectance after surface treatment satisfies the range specified in the present invention, but the amount of chromate coating layer adhered is large, and thus the groundability is poor.

Example 3 Using the same original plate as in Example 2, the ratio of each component of the chromate treatment liquid shown in Table 4 was variously changed, and the coverage was 85 to 90.
%, Adhesion amount: A test material coated with a chromate coating layer in the range of 100 mg / m ² was prepared. Tables 6 to 9 show the performance evaluations of the obtained test materials.

[0102]

[Table 6]

Table 6 shows the reduction ratio of chromium: Cr ³⁺ / (Cr ³⁺
+ Cr ⁶⁺ ) was investigated, and the composition of the chromate treatment liquid other than that was the same as in Table 3. No. 9-13
Is an example in which the reduction rate of chromium satisfies the preferred range of the present invention, and since the degree of change in total reflectance after chromate treatment is 0.80 or less, it is excellent in fingerprint resistance, corrosion resistance, paintability, and Good groundability and weldability.

On the other hand, N, which has a low reduction rate of chromium,
O.14 had excellent fingerprint resistance, but was inferior in paintability and could not have all the desired performance. In addition, No. 15 is an example in which the reduction rate of chromium is high,
Inferior in fingerprint resistance, corrosion resistance and paintability.

[0105]

[Table 7]

Table 7 shows an inorganic colloid compound (SiO ₂ /
The influence of the chromic acid ratio) was investigated, and the composition of the chromate treatment liquid other than that was the same as in Table 3. No. 16 ~
No. 20 is an example in which the addition ratio of the inorganic colloidal compound satisfies the preferred range of the present invention, and since the degree of change in total reflectance after chromate treatment is 0.80 or less, it is excellent in fingerprint resistance and corrosion resistance, Good paintability, groundability, and weldability.

On the other hand, No. 21, in which the addition ratio of the inorganic colloidal compound is small, has good fingerprint resistance, but is inferior in corrosion resistance and paintability. Further, No. 22 is an example in which the addition ratio of the inorganic colloidal compound is large, and is inferior in all the performance.

[0108]

[Table 8]

Table 8 shows the effect of phosphoric acid, and the composition of the chromate treatment solution other than that was the same as that in Table 4. Nos. 23 to 27 are examples in which the addition ratio of phosphoric acid satisfies the preferable range of the present invention, and the degree of change in total reflectance after chromate treatment is 0.80 or less, and therefore, the fingerprint resistance is excellent and It also has good corrosion resistance, paintability, groundability, and weldability.

On the other hand, N containing a large proportion of phosphoric acid was added.
No. 28 of o.29 has good fingerprint resistance, but is inferior in corrosion resistance and paintability, and has a small addition ratio of phosphoric acid.
Is also inferior in earthing property.

[0111]

[Table 9]

Table 9 shows the effect of the silane coupling agent, and the composition of the chromate treatment liquid other than that is the same as that in Table 4. Nos. 30 to 34 are Examples in which the addition ratio of the silane coupling agent satisfies the preferred range of the present invention, and the change rate of total reflectance after chromate treatment is 0.
Since it is 80 or less, it has excellent fingerprint resistance, corrosion resistance,
Good paintability, groundability, and weldability.

On the other hand, No. 35 with a small addition ratio of the silane coupling agent had unevenness, was inferior in corrosion resistance and paintability, and had a large addition ratio of the silane coupling agent No. 36. Then, it can be seen that the performance improving effect is saturated.

Embodiment 4 This embodiment, and Embodiments 5 and 6 described later are the third embodiment of the present invention.
This is an examination of the surface-treated steel sheet of. Chromate-treated steel sheet obtained by subjecting electrogalvanized steel sheet (zinc deposit: 20 g / m ² ) to reactive chromate treatment (Cr deposit 2
0 mg / m ² , total reflectance about 72%) was used as a master plate. As the treatment liquid applied to the original plate, an inorganic / organic composite coating treatment liquid having the composition shown in Table 10 was used. The lithium silicate used as the silicate is “lithium silicate 45” manufactured by Nissan Chemical Industries, Ltd., and the colloidal silicate is colloidal silica “Snowtex 4” manufactured by Nissan Chemical Industries, Ltd.
0 ”was used. As the organic resin, "Superflex 110" manufactured by Daiichi Kogyo Seiyaku Co., Ltd., and as the solid lubricant, "Chemipearl W95 manufactured by Mitsui Petrochemical Co., Ltd."
0 ”(particle diameter 0.6 μm) was used for each. The Na concentration and K concentration in the inorganic / organic composite film were measured by acid dissolution / ICP emission spectrometry.

[0115]

[Table 10]

The above original plate was coated with this inorganic / organic composite coating solution to obtain a coating layer with a Si deposition amount of 0.02 to 0.6 g.
/ M ² After controlling so as to be in the range, 1 in a hot air drying oven
A test material was prepared by drying at 00 ° C for 1 minute. Table 11 shows the performance evaluation of the obtained test materials. The coverage of the inorganic / organic composite coating was controlled by variously changing the roughness of the original plate.

[0117]

[Table 11]

Nos. 1 to 6 are Examples in which the degree of change in total reflectance after surface treatment satisfies 0.80 or less, which is the range defined by the present invention, and the total reflectance after application of the artificial fingerprint liquid is The degree of change is 0.90 or more, which is the range specified in the present invention,
It can be seen that it has excellent fingerprint resistance.

On the other hand, Nos. 7 and 8 are comparative examples in which the degree of change in total reflectance after surface treatment exceeds 0.80 because the amount of Si deposited in the coating layer is small, and the artificial fingerprint liquid coating is applied. It can be seen that the degree of change in total reflectance after that is less than 0.90, and the fingerprint resistance is poor. Further, Nos. 9 and 10 are excellent in fingerprint resistance, but are inferior in earthing property due to a large amount of Si attached in the coating layer. In Nos. 11 and 12, since the reflectance ratio does not satisfy the requirements of the present invention, the total reflectance change degree after the surface treatment is 0.
It exceeds 80 and is inferior in fingerprint resistance.

Example 5 Using the same original plate as in Example 4, the composition ratio of the inorganic-organic composite coating solution shown in Table 10 was variously changed to obtain a coverage of 85.
A test material coated with an inorganic / organic composite coating layer in the range of ˜90% and Si attachment amount of 0.1 g / m ² was prepared. Tables 12 to 16 show the performance evaluations of the obtained test materials.

[0121]

[Table 12]

Table 12 shows the influence of the Li / Si ratio, and the composition of the treatment liquid other than that is the same as that of Table 10. Nos. 13 to 17 are Examples in which the Li / Si ratio satisfies the preferred range of the present invention, and since the degree of change in total reflectance after the composite film treatment is 0.80 or less, the fingerprint resistance is excellent and Good deep drawability, dynamic friction coefficient (lubricity), corrosion resistance, paintability, and earthing property.

On the other hand, No. 1 having a small Li / Si ratio.
No. 18 was found to be excellent in fingerprint resistance because the degree of change in total reflectance after the composite coating treatment satisfied the requirements of the present invention, but was inferior in all performances except groundability. In addition, Li / S
In No. 19 having a large i ratio, the degree of change in total reflectance after the composite film treatment does not satisfy the requirements of the present invention, so that the fingerprint resistance is lowered,
The deep drawability and paintability were also poor.

[0124]

[Table 13]

Table 13 shows the effect of the addition concentration of the organic resin, and the composition of the treatment liquid other than that is the same as that of Table 10. Nos. 20 to 24 are examples in which the addition concentration of the organic resin satisfies the preferred range of the present invention, and the degree of change in total reflectance after the inorganic / organic composite film treatment is 0.80 or less, and thus the fingerprint resistance. In addition to excellent properties, it also has good deep drawability, lubricity, corrosion resistance, paintability, and groundability.

On the other hand, No. 25, in which the concentration of the organic resin added was low, was good in fingerprint resistance but inferior in corrosion resistance and paintability. Further, No. 26 is an example in which the organic resin concentration is high, and it is inferior in deep drawing workability, paintability, and groundability.

[0127]

[Table 14]

Table 14 shows the effect of the addition concentration of the solid lubricant, and the composition of the treatment liquid other than that is the same as that of Table 10. Nos. 27 to 31 are examples in which the addition concentration of the solid lubricant satisfies the preferable range of the present invention, and the degree of change in total reflectance after the inorganic / organic composite coating treatment is 0.80 or less, It has excellent fingerprint properties, deep drawability, lubricity, corrosion resistance, paintability, and groundability.

On the other hand, No. 33, which has a high solid lubricant addition concentration, has good fingerprint resistance, but is inferior in corrosion resistance and paintability, and has a low solid lubricant addition concentration N.
O.32 is inferior in deep drawing workability and lubricity because the lubrication improving action is not sufficiently obtained.

[0130]

[Table 15]

Table 15 shows the influence of the particle size of the solid lubricant, and the composition of the treatment liquid other than that is the same as that of Table 10. Nos. 34 to 38 are examples in which the particle size of the solid lubricant satisfies the preferred range of the present invention, and the degree of change in total reflectance after the inorganic / organic composite film treatment is 0.80 or less, It has excellent fingerprint properties, deep drawability, lubricity, corrosion resistance, paintability, and groundability. On the other hand, the solid lubricant has a small particle size No. 39 and a large particle size No.
40 is inferior in deep drawing workability, lubricity, corrosion resistance, and paintability.

[0132]

[Table 16]

Table 16 shows the effects of Na and K existing in the film, and the compositions of the other processing solutions are shown in Table 1.
Same as 0. Nos. 41 to 45 are Examples in which the concentrations of Na and K satisfy the preferred range of the present invention.
Since the degree of change in total reflectance after the organic composite film treatment is 0.80 or less, the fingerprint resistance is excellent, and the deep drawing workability, lubricity, corrosion resistance, paintability, and earthing property are also good.

On the other hand, No. 46 having a slightly high concentration of Na and K is inferior in corrosion resistance and paintability, and No. 47 having a higher concentration as compared with No. 46 has a fingerprint resistance and a deep fingerprint resistance. The drawability was also adversely affected.

Example 6 In this example, the effect of the addition of a silane coupling agent was examined. In Example 4, the Si adhesion amount was 0.2.
A test material was produced in the same manner as in Example 4 except that the amount was 5 g / m ² . Table 17 shows the performance evaluation of the obtained test materials.

[0136]

[Table 17]

First, as is clear from the results shown in the table, no influence of the addition of the silane coupling agent on the fingerprint resistance was observed. Nos. 1 to 8 are examples in which the content of the silane coupling agent satisfies the preferred range of the present invention, and the degree of change in total reflectance after the composite film treatment is 0.80 or less, and thus fingerprint resistance. It is also excellent in deep drawing workability and paintability.

On the other hand, No. 9 containing no silane coupling agent and No. 10 containing a small amount of silane coupling agent satisfy the requirements of the present invention for the degree of change in total reflectance after the composite film treatment, and thus the fingerprint resistance. It was found that the secondary adhesion was inferior although the excellent property was obtained. Further, in Nos. 11 to 13 containing a large amount of the silane coupling agent, the deep drawing workability was deteriorated.

[0139]

EFFECTS OF THE INVENTION The present invention is configured as described above, and has good fingerprint resistance even if the surface treatment coating layer does not completely cover the original plate, and the fingerprint is obtained regardless of the surface roughness of the original plate. It has been possible to provide a surface-treated steel sheet having a unique characteristic that the traces thereof are inconspicuous due to a small change in the appearance after the adherence.

As a result, in the case of the surface-treated steel sheet provided with the chromate coating layer, it has not only fingerprint resistance but also excellent corrosion resistance, paintability, groundability and weldability, and In the case of a surface-treated steel sheet provided with an inorganic / organic composite coating containing an acid-alkali metal salt and an organic resin, in addition to the fingerprint resistance, corrosion resistance, etc. described above, excellent workability, especially deep drawing workability, is required. I was able to prepare.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for explaining a volume of a recess and a covered volume.

FIG. 2 is a schematic diagram for explaining a coated surface portion.

Claims (23)

[Claims] 1. A surface-treated steel sheet having a coating layer for improving fingerprint resistance on at least one surface, the total reflectance R ₁ of the coated surface of the surface-treated steel sheet and the total reflectance of the original sheet before the surface treatment. A surface-treated steel sheet excellent in fingerprint resistance, characterized in that R ₀ satisfies the following relational expression (1). R ₁ ≦ 0.80 R ₀ (1) where R ₀ : total reflectance of original plate R ₁ : total reflectance of surface-treated steel sheet 2. The total reflectance R ₂ of the coated surface when an artificial fingerprint liquid consisting of a saturated solution of white petrolatum-acetone at 50 ° C. is coated on the coated surface satisfies the following relational expression (2). The surface-treated steel sheet according to claim 1. R ₂ ≧ 0.90 R ₁ (2) where R _{1 is} the total reflectance of the surface-treated steel sheet R ₂ : The total reflectance of the coated surface after applying the artificial fingerprint liquid to the surface-treated steel sheet 3. The surface-treated steel sheet according to claim 1, wherein the original sheet before surface treatment is a zinc or zinc alloy plated steel sheet, or a chemical conversion treatment steel sheet obtained by subjecting the steel sheet to chromate treatment. 4. The surface-treated steel sheet according to claim 1, wherein the coating layer for improving fingerprint resistance is substantially made of an organic resin. 5. The volume of the portion covered by the coating layer is 80% or more and 100% or more of the volume of the concave portion on the surface of the original plate.
The surface-treated steel sheet according to claim 4, which is less than 70% and less than 100% of the total surface area of the surface-treated steel sheet after coating. 6. The surface-treated steel sheet according to claim 1, wherein the coating layer for improving fingerprint resistance is substantially made of silicate. 7. The surface area of the portion covered by the coating layer is 70% or more of the total surface area of the surface-treated steel sheet after coating 10
The surface-treated steel sheet according to claim 6, which is less than 0%. 8. The coating layer for improving fingerprint resistance contains an alkali metal silicate, or an alkali metal silicate and a silicic acid colloid, and further contains an organic resin and a solid lubricant. The acid alkali metal salt is lithium silicate, and the atomic ratio of Li to Si in the coating layer: Li / Si is 0.
2 to 0.6, the content of the organic resin is 0.5 to 10% by weight,
The surface-treated steel sheet according to claim 1, wherein the content of the solid lubricant is 0.25 to 2% by weight. 9. The surface area of the portion covered by the coating layer is 70% or more of the total surface area of the surface-treated steel sheet after coating 10
The surface-treated steel sheet according to claim 8, which is less than 0%. 10. The surface-treated steel sheet according to claim 8, wherein the total content of Na and / or K present as impurities in the coating layer is suppressed to 1.0% by weight or less. 11. The surface-treated steel sheet according to claim 8, wherein an amount of the coating layer attached is 0.025 to 0.5 g / m ² in terms of Si weight. 12. A solid lubricant having a particle size of 0.10 to 1 μm.
The surface-treated steel sheet according to any one of claims 8 to 11. 13. The surface-treated steel sheet according to claim 8, wherein the coating layer contains a silane coupling agent in an amount of 1.0 to 10% by weight. 14. The surface-treated steel sheet according to claim 13, wherein the silane coupling agent is one or more selected from the group consisting of silane coupling agents represented by the following formula (3) or (4). Embedded image (In the formula, A ₁ and A ₅ represent a lower alkyl group, and A ₂ , A ₃ and A ₄ represent a lower alkoxy group) 15. The surface-treated steel sheet according to claim 13, wherein the silane coupling agent is one or more selected from the group consisting of silane coupling agents represented by the following formula (5) or (6). Embedded image (In the formula, A ₀ represents a glycidoxy group, A ₆ represents a lower alkylene group, and A ₂ , A ₃ , A ₄ and A ₅ have the same meanings as described above.) 16. The surface-treated steel sheet according to claim 1, wherein the coating layer for improving fingerprint resistance is a chromate coating layer. 17. The surface area of the portion covered by the coating layer is 80% or more of the total surface area of the surface-treated steel sheet after coating.
The surface-treated steel sheet according to claim 16, which is less than 00%. 18. The amount of the chromate coating layer deposited is metallic Cr.
The surface-treated steel sheet according to claim 16 or 17, which has a conversion of 10 to 250 mg / m ² . 19. The chromate coating layer is mainly composed of chromic acid having a reduction ratio of chromium: Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ ) of 0.10 to 0.5, and further comprises an inorganic colloid compound and phosphoric acid. The surface-treated steel sheet according to any one of claims 16 to 18, which is formed by applying a chromate treatment liquid containing a compound and a silane coupling agent onto the surface of the original plate and drying it. 20. The surface-treated steel sheet according to claim 19, wherein the inorganic colloid compound in the chromate treatment liquid is contained in an amount of 1.0 to 10 with respect to a chromic acid conversion value of 1. 21. The surface-treated steel sheet according to claim 19, wherein the phosphoric acid compound in the chromate treatment liquid solution is contained in an amount of 0.05 to 0.5 with respect to a chromic acid conversion value of 1. 22. The surface-treated steel sheet according to claim 19, wherein the silane coupling agent in the chromate treatment liquid is contained in an amount of 0.5 to 5 with respect to a chromic acid conversion value of 1. . 23. Reduction rate of chromium: Cr ³⁺ / (Cr ³⁺ +
Cr ⁶⁺ ) is mainly 0.10 to 0.5, and a chromate treatment liquid containing an inorganic colloid compound, a phosphoric acid compound, and a silane coupling agent is applied to the original plate surface and dried. 23. The method according to claim 16,
A method for producing a surface-treated steel sheet according to any one of 1.