JPH08100272A - Lubricated steel sheet having excellent conductivity and method for producing the same - Google Patents

Abstract

(57) [Summary] [Constitution] The surface of a galvanized steel sheet or a zinc-based plated steel sheet has a chromate film with an adhesion amount of 20 to 100 mg / m ² in terms of Cr, and the chromate film has a melting point of 80. ~ 160 ℃
It is a modified polyolefin wax that is
A colloidal silica having a weight ratio of 0.1 to 2 and a silica-modified polyolefin wax containing a silane coupling agent having a weight ratio of 0.2 to 5 with respect to the colloidal silica are contained in a ratio satisfying the following formula (1). , The total SiO ₂ / Cr weight ratio in the chromate film is 2 or less, and
Chromate film Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ ) ratio is 0.3 to 0.9
Lubricated steel sheet. Cr amount in chromate film: wax amount (weight ratio) = 1: (0.5 to 4) (1) This steel sheet can be easily manufactured by the method of the present invention. [Effect] It is excellent in conductivity, lubricity and corrosion resistance, and has fingerprint resistance, and is particularly suitable for use as a box for precision electronic equipment requiring electromagnetic wave shielding properties.

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 used for automobiles, home electric appliances, building materials and the like, and more particularly to a lubrication-treated steel sheet having excellent conductivity and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, in order to prevent environmental pollution and reduce manufacturing costs, manufacturers of home electric appliances, automobiles, etc., have a lubricating property instead of applying a press oil to the surface of a plated steel plate during forming. Oilless press working using the applied surface-treated steel sheet is performed.
This eliminates the need for a degreasing process and further eliminates the painting process after processing.

As a lubricated steel sheet used for such a purpose, various coating compositions have been developed.
At present, what is often used is one in which a chromate-treated layer is provided on a zinc-based plated steel sheet, and an organic resin film containing a solid lubricant is formed on it (see, for example, Japanese Patent Laid-Open No. Hei 10 (1999) -135242).
1-301332).

However, as the scope of application of lubricated steel sheets has expanded, it has become necessary to have functions other than lubricity. In particular, there are rapidly increasing applications in which a lubricated steel sheet having conductivity is required. This is because, in recent years, it is necessary to satisfy the electromagnetic wave shielding property required for particularly precision electronic devices.

An example of a member requiring an electromagnetic wave shield is a box of electronic equipment.

The box is required not to leak the electromagnetic waves generated from the oscillation circuit, the switching circuit, etc. inside the electronic device to the outside and to prevent the electromagnetic noise from the outside to enter the inside. Conventionally, untreated plated steel sheets or plated steel sheets that have only been subjected to chromate treatment have been used, so it is possible to maintain electrical conductivity between the steel sheets that make up the box by caulking, screwing, etc. during box forming. It was possible to secure the electromagnetic wave shielding property by grounding the box.

However, by using a lubricated steel sheet having both a chromate film and an organic film, the contact resistance between the steel sheets increases, and the electromagnetic wave shielding property cannot be secured.

As a countermeasure against this, a lubricated steel sheet having electrical conductivity has been demanded. For example, Japanese Patent Application Laid-Open No. 3-2709
Japanese Unexamined Patent Publication No. 32 discloses a lubricated steel sheet having a resin film with an electrically conductive resin added as an upper layer. Although a certain degree of conductivity can be obtained by using this steel sheet, its electrical conductivity is not sufficient because it has an organic film on the upper layer like the conventional lubricated steel sheet. Further, the conductive resin used is a very special resin such as a doped polyacetylene resin or polyaniline resin, which is not generally available,
Moreover, since the manufacturing cost thereof is extremely high, it cannot be said that it is a versatile lubricated steel sheet.

[0009]

SUMMARY OF THE INVENTION In view of such circumstances, the present invention has been made to provide a lubricated steel sheet having excellent conductivity, and a method for inexpensively producing the steel sheet. is there.

[0010]

[Means for Solving the Problems] Having conductivity and lubricity,
In order to obtain a surface-treated steel sheet with excellent corrosion resistance, it is the most practical method to form only a highly corrosion-resistant chromate film on the surface of the base steel sheet and to add a solid lubricant to this chromate film. Is. The inventors of the present invention conducted a study based on this idea, and as a result, if a predetermined amount of a polyolefin-based wax can be uniformly dispersed in a chromate film having high corrosion resistance, lubricity, conductivity and corrosion resistance can be improved. It was found that a good lubricated steel sheet can be obtained in all cases.

However, the stability of the chromate treatment liquid must be improved before it can be used industrially. Coating type chromate treatment liquids generally have a pH of 1-2.
In contrast to the strong acid, the aqueous dispersion of polyolefin wax is adjusted to be alkaline in order to stabilize the dispersion of particles, so when the chromate treatment liquid and the aqueous dispersion of wax are mixed, the wax This is because it loses stability and solidifies immediately.

In order to stabilize the wax, it is possible to add a surfactant or a water-dispersible or water-soluble resin. However, since the surfactant lowers the water resistance of the chromate film and thus the corrosion resistance, and the water-dispersible or water-soluble resin lowers the conductivity, their use is not preferable.

Therefore, as a result of further studies, the present inventors have found that by modifying a polyolefin wax with a silane coupling agent and colloidal silica, it can be stably mixed with a chromate treatment liquid which is a strong acid. The present invention has been completed.

The gist of the present invention is to provide the following lubricated steel sheet,
And a method of manufacturing the steel sheet as described below.

A galvanized steel sheet or a zinc-based galvanized steel sheet is a lubricated steel sheet having a chromate film having an adhesion amount of 20 to 100 mg / m ² in terms of Cr, the chromate film having a melting point of 80 to A modified polyolefin wax at 160 ° C, which contains silica-modified polyolefin wax satisfying the following formulas (2) and (3) in a ratio satisfying the following formula (1). The total SiO ₂ / Cr weight ratio in
^{Moreover, the} ratio of Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ ) in the chromate film is 0.3.
A lubricated steel sheet with excellent conductivity, which is characterized by a value of up to 0.9.

Cr amount: Wax amount (weight ratio) = 1: (0.5 to 4) (1) where Cr amount: Cr content in the chromate film Wax amount: Silica-modified polyolefin wax in the chromate film Content Silica-modified polyolefin wax amount: Colloidal silica amount (weight ratio) = 1: (0.1 to 2) ... (2) Colloidal silica amount: Silane coupling agent amount (weight ratio) = 1: (0.2 to 5) ・ ・ ・ (3) The amount of chromate treatment liquid deposited on the surface of galvanized steel sheet or galvanized steel sheet converted to Cr is 20-100 mg / m ²
A method for producing a lubricated steel sheet, in which the chromate treatment liquid is Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ )
A chromate-treated solution partially reduced to a ratio of 0.3 or more and less than 0.6 and silica-modified polyolefin wax prepared as described below in a weight ratio of 0.5 to 0.5 with respect to a Cr content of 1 to
The ratio of 4 and the total SiO ₂ / Cr in the chromate film
A method for producing a lubricated steel sheet having excellent electrical conductivity, which is characterized in that the weight ratio is a mixture of 2 or less.

[Preparation of Silica-Modified Polyolefin Wax] A weight ratio to colloidal silica to which a silane coupling agent is added later in an aqueous dispersion of a polyolefin wax having a melting point of 80 to 160 ° C. and containing no surfactant.
0.2 to 5 is added and stirred, and then colloidal silica is added to the silica-modified polyolefin wax in a weight ratio of 0.1 to 2 and stirred.

The method for producing a lubricated steel sheet having excellent conductivity as described above, further comprising adding a reducing agent to the partially reduced chromate treatment liquid in an amount of 0.5 to 2 molar equivalents relative to unreduced Cr ⁶⁺ .

[0019]

The present invention will be described in detail below.

Zinc-plated steel sheet or zinc-based plated steel sheet which is the base material of the lubricated steel sheet of the present invention (above invention), and zinc used as the base material of the method of manufacturing a lubricated steel sheet of the present invention (above invention). The plated steel sheet or zinc-based plated steel sheet is not particularly limited. For example,
Electric sub-galvanized steel sheet, hot-dip galvanized steel sheet, zinc-13%
A nickel electroplated steel sheet, a zinc-5% aluminum hot-dip galvanized steel sheet, a zinc-55% aluminum hot-dip galvanized steel sheet, etc. may be used.

Prior to the chromate treatment, the plating surface may be subjected to activation treatment, displacement plating, electrolytic treatment or the like. Examples of the activation treatment include alkaline degreasing and electrolytic degreasing.As an example of the displacement plating, adhesion and flash plating of cobalt or nickel performed to improve corrosion resistance, and as an example of the electrolytic treatment, ,
There is blackening treatment by anodic oxidation.

A lubricated steel sheet of the present invention is a steel sheet having a chromate film containing a silica-modified polyolefin wax satisfying the above-mentioned predetermined conditions formed on the surface of the base steel sheet.

In the chromate film, the content of Cr and the content of silica-modified polyolefin wax in the film must satisfy the following formula (1).

Cr amount: Wax amount (weight ratio) = 1: (0.5 to 4) (1) where Cr amount: Cr content in the chromate film Wax amount: Silica-modified polyolefin wax in the chromate film Content If the content of the silica-modified polyolefin wax in the chromate film is less than 0.5 by weight ratio with respect to the Cr content in the chromate film, the lubricity of the steel sheet is insufficient,
When it exceeds 4, the conductivity of the chromate film becomes insufficient.

The silica-modified polyolefin wax contains colloidal silica in a weight ratio of 0.1 to 2 with respect to the wax, and a silane cup with a weight ratio of 0.2 to 5 in the colloidal silica. It is necessary to include a ring agent. If the content of at least one of the colloidal silica and the silane coupling agent is out of this range, the desired effect cannot be obtained, as described later.

Further, the total SiO ₂ / in the chromate film
The weight ratio of Cr, that is, the total amount of SiO _{2 with} respect to the amount of Cr in the chromate film must be 2 or less by weight.

When this ratio exceeds 2, cohesive failure of the chromate film is apt to occur, corrosion resistance is deteriorated, and excessive silica causes deterioration of lubricity.

The silica-modified polyolefin wax is
It is necessary to use a modified polyolefin wax having a melting point of 80 to 160 ° C. In the case of a steel sheet obtained by using a polyolefin wax having a melting point of less than 80 ° C., the wax particles are too soft to prevent direct contact between the metal mold and the metal during press working, resulting in galling. Further, in the case of a steel sheet using a polyolefin wax having a melting point of more than 160 ° C, the wax particles are too hard to be deformed during processing, so that lubricity is not exhibited.

The attached amount of the chromate film is converted to Cr.
It is necessary to be 20 to 100 mg / m ² . 20 mg adhered amount
If it is less than / m ² , the corrosion resistance is insufficient and the adhesion amount is 100
If it exceeds mg / m ² , not only the conductivity becomes insufficient, but
The film is colored and a good appearance cannot be obtained.

The Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ ) ratio of the chromate film must be 0.3 to 0.9. The lubricated steel sheet of the present invention is produced by a coating method, as described below, but the corrosion resistance of the coating type chromate includes a barrier effect of a film made of oxides and hydroxides of Cr ³⁺ and contained in the film. It is considered that this is caused by the self-repairing action of the film by Cr ⁶⁺ . Therefore, if the Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ ) ratio is less than 0.3, a robust film will not be formed,
Corrosion resistance decreases. Also, the Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ ) ratio is
If it exceeds 0.9, Cr ⁶⁺ will be insufficient and it will be impossible to self-repair scratches on the film.

The lubricated steel sheet of the present invention can be manufactured by the method of the present invention as described above or.

The chromate treatment liquid used in the method of the present invention (the chromate treatment liquid before the addition of the silica-modified polyolefin wax) has a Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ ) ratio within a predetermined range described later. It is an ordinary coating type chromate treatment liquid that is partially reduced.

The method for producing the chromate treatment liquid before adding the wax is not particularly limited. Polyhydric alcohol,
Those prepared by reducing chromic acid with a polycarboxylic acid or the like are preferable. As the polyhydric alcohol, ethylene glycol, propylene glycol, glycerin or the like may be used, and as the polyhydric carboxylic acid, succinic acid, adipic acid or the like may be used. Alternatively, a commercially available partially reduced chromate treatment liquid may be used.

Cr in the chromate treatment liquid before adding wax
^{The 3 +} / (Cr ³⁺ + Cr ⁶⁺ ) ratio can be controlled by adjusting the addition amount of these reducing agents. In the coating type chromate treatment, if the drying temperature is about 100 ° C., the treatment liquid of ^{Cr 3+ / (Cr 3+ + Cr} 6+) ratio and Cr ³⁺ of the formed film
The / (Cr ³⁺ + Cr ⁶⁺ ) ratio is considered to be almost the same. Therefore,
The Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ ) ratio specified in the above invention is 0.3.
To form a chromate film of ~ 0.9, control the Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ ) ratio in the chromate treatment solution to 0.3 or more. However, Cr ³⁺ / (Cr ³⁺ + C in the treatment liquid
When r ⁶⁺ ) is increased to 0.6 or more, the pot life of the treatment liquid becomes extremely short and gelation occurs in a few days. Therefore, the value should be less than 0.6 in the above method. In addition, in the chromate film
To increase the Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ ) ratio to 0.6 or more, the method described below may be used.

Phosphoric acid, polyphosphoric acid or the like may be added to the chromate treatment solution as a film forming aid. Further, hydrosilicofluoric acid, hydrofluoric acid or the like may be added to accelerate the interfacial reaction.

The silica-modified polyolefin wax used in the method of the present invention is an ordinary polyolefin wax whose surface is treated with colloidal silica. The polyolefin is preferably polyethylene, polypropylene or the like, and has a spherical shape. The average particle size of polyolefins can range from submicron to several microns, but if the average particle size is less than 0.3 μm, lubricity may not be sufficient. In some cases, the dispersion stability is not sufficient, so that a particle size of about 0.3 to 5 μm is preferable.

As mentioned above, the polyolefin wax does not contain a surfactant and has a melting point of 80 to 160 ° C.
Use the one.

The average particle size of the colloidal silica added after adding the silane coupling agent to the aqueous dispersion of polyolefin wax is preferably 10 to 100 nm. Particle size
Those having a size of less than 10 nm are not only industrially inexpensive, are not easily available in large quantities, but tend to be aggregated. On the other hand, if the particle size exceeds 100 nm, it easily aggregates,
Further, the surface modification of the wax is difficult. As colloidal silica, there are Snowtex-O, Snowtex-OL and the like (both are Nissan Chemical Co., Ltd.).
Made).

There are a chemical method and a mechanochemical method for treating the surface of the polyolefin wax with colloidal silica. In the method of the present invention, the chemical method, that is, the wax surface is treated with a silane coupling agent. However, it is preferable to apply the method of reacting with colloidal silica after that. The method will be specifically described below.

As the aqueous dispersion of the polyolefin wax, a commercially available product may be used. However, it does not contain a surfactant for keeping the dispersion state stable. This not only causes the surfactant to reduce the water resistance of the chromate film, but also causes foaming during roll coating,
This is because the coatability is impaired.

Examples of the silane coupling agent added to the aqueous dispersion of polyolefin wax include vinyltriethoxysilane, vinyl-tris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane and γ-glyce. Sidoxypropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, N-β
-(Aminoethyl) -γ-aminopropyltrimethoxysilane or the like may be used. Preferred are epoxy silane coupling agents such as γ-glycidoxypropyltrimethoxysilane.

The above coupling agent is added to an aqueous dispersion of a polyolefin wax, and the mixture is stirred by a usual means such as a propeller stirrer and a stirring pump. A stirring time of about 10 to 30 minutes is sufficient. After that, add colloidal silica,
Stir further. The stirring method and time at this time may be the same.

The weight ratio of the silane coupling agent to the colloidal silica is 0.2 to 5, that is, colloidal silica: silane coupling agent (weight ratio) =
If the ratio is less than 0.2, sufficient silica particles cannot be adhered to the surface of the polyolefin wax, and the dispersibility of the wax cannot be ensured. If it exceeds, the silane coupling agent becomes excessive, and in order to promote the aggregation reaction between silica,
This is because the dispersion stability of the silica-modified wax is impaired.

The amount of colloidal silica added is 0.1 to 2 by weight with respect to the silica-modified polyolefin wax, that is, wax: colloidal silica (weight ratio) =
1: (0.1 to 2) If this ratio is less than 0.1, the effect of modifying the wax with silica is not sufficient and the wax cannot be dispersed in chromic acid. On the other hand, if it exceeds 2, the silica present on the surface of the wax becomes excessive and the silica itself agglomerates.

The silica-modified polyolefin wax prepared as described above was mixed with the above-mentioned Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ ) ratio.
Mix in the chromate treatment solution controlled to 0.3 or more and less than 0.6 and stir. Mix the Cr in the chromate treatment liquid
The silica-modified polyolefin wax is used in a weight ratio of 0.5 to 4 with respect to the content of 1. This is because, as described above, if it is less than 0.5, the lubricity of the steel sheet after the following steps is not sufficient, and if it exceeds 4, the electrical conductivity of the chromate film is insufficient. For the reasons described above, it is necessary to mix the chromate film so that the total SiO ₂ / Cr weight ratio is 2 or less.

The obtained chromate treatment liquid after the addition of the silica-modified polyolefin wax is applied to the surface of the base material by a usual method and dried to form a chromate film.
If the above chromate treatment liquid after the addition of wax is further coated with colloidal silica on the surface of the base material, this additional colloidal silica has fingerprint resistance that makes it difficult for fingerprints to adhere to the treated surface, and adhesion of the top coat. Contributes to the improvement of sex. However, as described above, it is necessary to suppress the addition amount so that the total SiO ₂ / Cr ratio becomes 2 or less.

As a method for applying the chromate treatment liquid, any method such as a roll coating method, a spray method and a dipping method may be used, and the drying may be carried out in a hot air oven, an infrared oven or the like.

The above-mentioned method is applied to Cr ³⁺ in the chromate film.
The method used to increase the / (Cr ³⁺ + Cr ⁶⁺ ) ratio to 0.6 or more, the Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ ) ratio used in the method
This is a method in which a reducing agent is further added to the chromate treatment solution partially reduced to about 0.3 to 0.6 before coating. The addition amount of the reducing agent in the second stage is 0.5 to 2 molar equivalent with respect to unreduced Cr ⁶⁺ . If it is less than 0.5 molar equivalent, the effect of reduction strengthening is small, and if it is added in excess of 2 molar equivalent, not only the effect of reduction strengthening is saturated, but also the corrosion resistance is deteriorated. The second-stage reducing agent may be added before or after the addition of the silica-modified polyolefin wax. Also, the method is the same as the method except that the reducing agent in the second stage is added. By this method, the Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ ) ratio is high (0.6 to 0.9)
A chromate film can be formed.

As described above, the method of the present invention is a method of coating the surface of the steel sheet only with the chromate film. Therefore,
It can be manufactured at a lower cost than a conventionally used zinc-plated steel sheet provided with a chromate treatment layer on which an organic resin film containing a solid lubricant is formed.

[0050]

[Embodiment] Electrogalvanized steel sheet (sheet thickness:
0.8 mm, coating weight: 40 g / m ^{2 on} one side, the lubrication-treated steel sheet obtained by applying the method of the present invention was tested for stability of chromate treatment liquid, lubricity of chromate film, conductivity, corrosion resistance and corrosion resistance. The fingerprint property was investigated.

[Preparation of Silica-Modified Polyolefin Wax] The polyolefin wax used is polyethylene wax (PE) and polypropylene wax (PP) having different melting points, which are spherical and have an average particle diameter of 1 μm.

The aqueous dispersion of polyolefin wax was assumed to contain no surfactant. For comparison, a nonionic surfactant added with 20% by weight based on the wax solid content was also used.

Colloidal silica has an average particle size of 20 nm.
I used the one.

As the silane coupling agent, γ-glycidoxypropyltrimethoxysilane (A) and γ-
Glycidoxypropylmethyldimethoxysilane (B) was used.

The above coupling agent was added to the above aqueous dispersion of polyolefin wax, and the mixture was stirred for 30 minutes with a propeller stirrer. After that, add colloidal silica,
The mixture was further stirred for 30 minutes to obtain a silica-modified polyolefin wax.

[Preparation of Chromate Treatment Liquid] The chromate treatment liquid before addition of wax was an aqueous solution of chromic acid to which ethylene glycol was added as a reducing agent, and a solution left standing for 24 hours after addition of the reducing agent was used.

The Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ ) ratio in the treatment liquid was controlled by changing the amount of ethylene glycol added.

A silica-modified polyolefin wax was added to this chromate treatment liquid to prepare a wax-containing chromate treatment liquid. Further, additional colloidal silica and a reducing agent (ethylene glycol) for two-step reduction were added as needed.

[Chromate Treatment] After the base steel sheet is degreased with alkali, the above wax-containing chromate treatment solution (hereinafter simply referred to as chromate treatment solution) is applied by a bar coater, and a predetermined steel sheet (baking) is performed using an electric oven. It was dried to the temperature.

Table 1 and Table 2 collectively show the preparation of the silica-modified polyolefin wax and the chromate treatment liquid, and the chromate treatment conditions.

The following tests were conducted on the obtained lubricated steel sheet.

[Stability of Chromate Treatment Solution] The treatment solution immediately after preparation was placed in a test tube, allowed to stand for 24 hours, and then examined by visual observation. The evaluation criteria are as follows, and in case of ○, it was considered good.

◯: No change Δ: Precipitation, but redispersion possible by stirring X: Precipitation and gelation [Lubricity] Dynamic friction coefficient and draw formability were evaluated. Dynamic friction coefficient was measured using a Bowden tester with a weight of 500 g and a diameter of 5 mm.
The steel balls of No. 2 were used and measured under the condition without oiling. The drawability was investigated by using a cylindrical drawing tester by observing the external appearance of the wall when the wrinkle pressing pressure was 1 ton, the punch speed was 5 mm / min, and the drawing ratio was 2.2 without oiling. The evaluation criteria are as follows:
In the case of the mark, it was considered good.

○: No galling △: Partial galling ×: All galling or unmoldable [Conductivity] Resistance value when the treated surfaces (surface area 1 cm ² ) are brought into contact with each other at a surface pressure of 150 g / cm ^2. Was measured. The evaluation criteria are as follows, and in case of ○, it was considered good.

○: 15 milliohms or less △: 15 milliohms or more and 25 milliohms or less ×: 25 milliohms or more [corrosion resistance] of the test surface (flat plate portion) by a salt spray tester
The time until white rust was generated on 10% was measured. The evaluation criteria are as follows, and in case of ○, it was considered good.

○: Exceeded 150 hours Δ: 100 to 150 hours ×: Less than 100 hours [Fingerprint resistance] Artificial sweat was applied to the test surface with a stamp, and the portion was visually observed. The evaluation criteria are as follows:
In the case of the mark and the mark of Δ, the result was good.

◯: Almost not visible Δ: Unclearly visible ×: Clearly visible The results of the investigation are shown in Tables 3 and 4. As is clear from this result, all chromate treatment liquids produced under the conditions specified in the present invention have good stability, and the formed chromate film has lubricity, conductivity, corrosion resistance and fingerprint resistance. It was good.

[0068]

[Table 1]

[0069]

[Table 2]

[0070]

[Table 3]

[0071]

[Table 4]

[0072]

INDUSTRIAL APPLICABILITY The lubricated steel sheet of the present invention is not only excellent in conductivity, lubricity and corrosion resistance, but also has fingerprint resistance, and in particular, it is used as a box for precision electronic equipment which requires electromagnetic wave shielding properties. And so on. This steel sheet can be easily and inexpensively manufactured by the method of the present invention.

Claims (3)

[Claims] 1. A lubrication-treated steel sheet having a chromate film having an adhesion amount of 20 to 100 mg / m ² in terms of Cr on the surface of a galvanized steel sheet or a zinc-based steel sheet, the chromate film having a melting point of This is a modified polyolefin wax at 80 to 160 ° C, and the following formula (2) and (3
) The silica-modified polyolefin wax satisfying the formula is contained in a ratio satisfying the formula (1) below, and the total SiO ₂ / Cr weight ratio in the chromate film is 2 or less and the chromate film contains Cr ³⁺ / (Cr ³⁺ + Cr ⁶⁺ ) ratio is 0.3 ~
A lubricated steel sheet with excellent conductivity, which is 0.9. Cr amount: Wax amount (weight ratio) = 1: (0.5 to 4) (1) where Cr amount: Cr content in chromate film Wax amount: Silica-modified polyolefin wax content in chromate film Silica Modified polyolefin wax amount: Colloidal silica amount (weight ratio) = 1: (0.1 to 2) ... (2) Colloidal silica amount: Silane coupling agent amount (weight ratio) = 1: (0.2 to 5) .. (3) 2. The amount of the chromate treatment liquid deposited on the surface of the galvanized steel sheet or the zinc-based steel sheet is 20 to 10 in terms of Cr.
A method for manufacturing a lubricated steel sheet, which comprises applying 0 mg / m ² and drying, wherein the chromate treatment liquid is Cr ³⁺ / (Cr ³⁺
+ Cr ⁶⁺ ) ratio of the silica-modified polyolefin wax prepared as follows in a chromate treatment solution partially reduced to a ratio of 0.3 to less than 0.6 at a weight ratio of 0.5 to 4 with respect to a Cr content of 1, And all in the chromate film
A method for producing a lubricated steel sheet having excellent conductivity, which is a mixture of SiO ₂ / Cr in a weight ratio of 2 or less. [Preparation of silica-modified polyolefin wax] 0.2 to 5 by weight ratio to colloidal silica to which a silane coupling agent is added later in an aqueous dispersion of a polyolefin wax having a melting point of 80 to 160 ° C and containing no surfactant. Of the colloidal silica is added to the silica-modified polyolefin wax in a weight ratio of 0.1 to
Add in a ratio of 2 and stir. 3. A lubricated steel sheet having excellent conductivity according to claim 2, wherein a reducing agent is further added to the partially reduced chromate treatment liquid in an amount of 0.5 to 2 molar equivalents relative to unreduced Cr ⁶⁺ . Manufacturing method.