JPH0813156A - Colored lubrication-treated galvanized steel sheet having high edge face corrosion resistance and its production - Google Patents

Abstract

PURPOSE:To produce a colored lubrication-treated steel sheet excellent in lubricity, corrosion resistance including edge face corrosion resistance and designing properties without adding pigments by subjecting a galvannealed steel sheet to chromating treatment and thereafter forming a specified lubricating resin film contg. silica particles and a basic additive thereon. CONSTITUTION:This steel sheet is a one in which the surface of a galvannealed steel sheet is applied with a chromate film of 10 to 150mg/m<2> coating weight expressed in terms of Cr, and the surface is applied with a resin film. This resin film is a one contg., by weight, 5 to 30% silica particles as SiO2, 0.5 to 30% lubricating function imparting agent and 1 to 10% basic alkali metal salt and contg. no pigments, and in which the weight of the dry film is regulated to 0.1 to 5g/m<2>. Furthermore, the alloying degree of the galvanized steel sheet is preferably regulated to 7 to 13%. Moreover, preferably, as the color tone after the treatment, the color system of L*a*b* in JIS-Z8729 is used, and 50<=L*<=62, -1<=a*<=0 and -2<=b*<=0 are regulated.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a colored lubrication having a surface appearance suitable for use as an exterior for automobiles, home appliances, building materials, etc., and having excellent lubricity and corrosion resistance, particularly end face corrosion resistance. A treated zinc-based plated steel sheet.

[0002]

2. Description of the Related Art In recent years, preventive measures against the destruction of the global environment have been taken up as a global problem, and prevention of the destruction of the ozone layer, which protects us from intense ultraviolet rays, is an important issue. The use of organic solvents such as chlorofluorocarbons and trichlene, which causes water pollution, has been regulated, including the adoption of the CFC regulation protocol in Montreal in September 1987 and the enactment of domestic laws in 1988 in Japan. It has become.

Generally, when processing a steel sheet, press oil is applied to reduce frictional resistance. The applied press oil is degreased in the degreasing step after processing. Trichloroethane, which is often used in this degreasing process, is an ozone depleting substance, and is scheduled to be completely abolished in 1995.

Further, from the viewpoint of improving the environment of the press work workplace and reducing the cost by omitting the degreasing process, there is an increasing need for a lubricated steel sheet which has been subjected to a lubrication process in advance and which can omit the press oil application-degreasing process. From such circumstances, as described in the following publications,
Various lubricated steel sheets have been proposed so far.

Japanese Unexamined Patent Publication No. 3-96337: A resin-coated steel sheet excellent in press workability in which a resin film containing fluororesin particles and silica particles in an acrylated epoxy resin is formed on the surface of a chromate-treated electrogalvanized steel sheet. . Japanese Unexamined Patent Publication No. 3-17190: Lubricity in which a film of montan wax oxide containing fluororesin particles and silica particles is formed on the surface of a zinc-plated steel sheet that has been chromated.
Surface-treated steel sheet with excellent corrosion resistance. JP-A-3-17189: A resin-coated steel sheet having excellent lubricity and corrosion resistance, in which a resin coating containing fluorine resin particles and silica particles in a urethane-modified polyolefin resin is formed on the surface of a chromate-treated galvanized steel sheet.

JP-A-3-28380: A coating layer of a carboxylated polyethylene-based dispersion containing a chromate film formed on the surface of a zinc-based (= zinc or zinc alloy) electroplated steel sheet and containing a fluororesin thereon. Surface-treated steel sheet with excellent lubricity and corrosion resistance. JP-A-3-16726: Forming a chromate film on the surface of a zinc-based electric or hot dip plated steel sheet, and a resin film containing silica and polyolefin wax in the resin having a hydroxyl group and / or a carboxyl group on the chromate film Lubricant resin treated steel sheet with excellent properties. These are all electrogalvanized and / or
Alternatively, a hot-dip galvanized steel sheet is used as a base material, and the color tone is inferior in design due to the metallic luster peculiar to the underlying zinc-based plating.

[0007] In recent years, from the viewpoint of cost reduction, there has been an attempt to apply these lubricated steel sheets to exterior steel sheets, which have conventionally used precoated steel sheets. Was difficult to apply.

As a lubricated steel sheet having a colored appearance, Japanese Unexamined Patent Publication (Kokai) No. 2-263633 discloses an organic material containing a zinc-based plated steel sheet on which a chromate film is formed, on which silica, polyethylene wax and a color pigment are contained. A highly corrosion-resistant colored thin film-coated steel sheet coated with a solvent-based coating composition has been proposed. This coated steel sheet has a high manufacturing cost because the resin film is colored with a pigment. Furthermore, since it is difficult to disperse the pigment uniformly in the paint, it is difficult to form a uniformly colored resin film in a stable manner. Becomes

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to apply as an exterior, which can be processed by omitting the press oil application-degreasing step, and is colored to have a preferable appearance without using a pigment. It is to provide a surface-treated steel sheet having excellent lubricity, corrosion resistance, and designability.

A more specific object of the present invention is to exhibit the same lubricating performance as that of the above-mentioned conventional lubricated steel sheet (that is, it has excellent lubricity and is effective for extreme pressure in strong working and temperature rise of molds). You can endure it enough), at the same time,
To provide a colored lubricated hot-dip galvanized steel sheet that is colored without using a pigment and has the same design characteristics as a pre-coated steel sheet, yet retains high corrosion resistance even after processing the end surface of the steel sheet and the steel sheet, and is also weldable. That is.

[0011]

[Means for Solving the Problems] As seen in the above-mentioned prior art, when a lubricating resin film containing a lubricating component is formed after chromate treatment on the surface of an electrogalvanized or hot-dip galvanized steel sheet, base metal plating is performed. The lubricity and corrosion resistance of the steel sheet can be improved.

The present inventor is keen to develop a lubricated steel sheet which has the design characteristics of a precoated steel sheet without adding a pigment and can be applied to the exterior, while taking advantage of these conventional techniques. As a result of examination, when a base material is a specific galvannealed steel sheet and chromate treatment is performed, and then a lubricative resin film containing silica particles and a lubricating component is formed, excellent lubricity and corrosion resistance are obtained. It was found that a surface-treated steel sheet having a calm gray color can be obtained (see Japanese Patent Application No. 5-174302). Then, as a result of further research, it was found that the addition of a specific basic additive in the resin film significantly improves the corrosion resistance especially on the end face and after processing.

The present invention has a chromate film having a Cr equivalent deposition amount of 10 to 150 mg / m ² and a resin film as an upper layer on the surface of a galvannealed steel sheet, wherein the resin film is a base resin. Silica particles (B) in (A) as SiO ₂ 5-30
% By weight, 0.5 to 30% by weight of a lubricating function-imparting agent (C), and 1 to 10% by weight of a basic alkali metal salt (D), containing no coloring pigment, and a dry film weight of 0.1 to 5 g / m ² The gist of the present invention is a colored and lubricated zinc-based plated steel sheet excellent in end face corrosion resistance, which is characterized by the above-mentioned lubricating resin film.

[0014] Preferably, this tinted lubricated zinc-based plated steel sheet has a surface color tone of JIS Z8729 in the L ^* a ^* b ^* color system of 50 ≤ L ^* ≤ 62, -1 ≤ a ^* ≤ 0,-. 2 ≤ b ^* ≤ 0
Is. In the L ^* a ^* b ^* color system, the L ^* value is a lightness index, and the larger the value, the brighter and the smaller the value the darker. a ^*
The value is the perceived chromaticity (chromaticity) index between red and green. The larger this value, the stronger the redness, and the smaller this value (the larger the absolute value of −), the stronger the greenness. The b ^* value is the perceived chromaticity index between yellow and blue. The larger the value, the stronger the yellowness, and the smaller (the larger the absolute value of −), the stronger the blueness. The color tone in which each value of L ^* a ^* b ^* is within the above range is substantially gray.

In a preferred embodiment, the lubricant function imparting agent
(C) is composed of a polyolefin wax having a softening point of 90 ° C. or higher and / or a fine powder of a fluorine resin having an average particle diameter of 5 μm or less.

This colored lubricated zinc-plated steel sheet is an alloyed hot-dip galvanized steel sheet with an alloying degree of 7 to 13% as a base material, and is first chromated to have a Cr-converted adhesion amount of 10 to 150 mg / after forming the chromate film of m ^2, 5 to 30 wt% of silica particles as SiO ₂ with respect to the nonvolatile content total amount, the lubricating function-imparting agent 0.5-30 wt%, and a basic alkali metal salt 1-10 It can be produced by forming a resin film having a dry film weight of 0.1 to 5 g / m ² on the chromate film by using a resin coating composition containing the pigment in an amount of 1% by weight and containing no coloring pigment.

[0017]

The colored and lubricated zinc-based plated steel sheet and the method for producing the same according to the present invention will be described in detail below.

Base material plated steel sheet The base material of the colored and lubricated steel sheet of the present invention is an alloyed hot-dip galvanized steel sheet (hereinafter abbreviated as GA steel sheet), that is, a hot-dip galvanized steel sheet is plated to form a plating film. In
It is a zinc-based plated steel sheet in which a part of Zn is alloyed with Fe as a base material. It is desirable that the GA steel sheet used as the base material has an alloying degree of the plating film (average Fe% in the plating film) within the range of 7 to 13%. The degree of alloying is more preferably 9 to
11%. GA steel sheets have a tendency that as the alloying progresses and the degree of alloying of the plating film increases, the unevenness of the plating surface increases and the surface roughness increases. For example, the GA steel sheet may be alloyed with Fe and then rolled by a skin pass (rolling rate 0 to 3%).

The colored and lubricated steel sheet of the present invention is a resin containing a chromate film formed on the plating film of the GA steel sheet, containing silica, a lubricating component, and a basic alkali metal salt and containing no pigment. A film is formed.
Even though the upper resin film is a clear type that does not contain pigment, the appearance of the resin film becomes dark due to the coating of the resin film, the metallic luster of the GA steel sheet disappears, and the preferred gray color tone is obtained. To give the design characteristics of pre-coated steel sheets.

The reason why the color tone changes in this way is that by using an alloyed hot-dip galvanized steel sheet with large surface irregularities as the base material, irregularities on the underlying plating surface cause irregular reflection of light, and the optical path length in the resin is As the length increases, the proportion of light absorbed in the resin increases, and it is considered that the light appears darker than the base GA steel plate.

In other platings such as electrogalvanizing plating and hot dip galvanizing, the surface is relatively smooth, so when the chromate film and the transparent resin film are coated, the change in color tone to darkening as described above does not occur. unacceptable. That is, this change in color tone is peculiar to the plating film of the GA steel sheet whose surface roughness is increased by the heat treatment.

The color tone obtained by this darkening changes depending on the surface roughness of the plating film of the GA steel sheet. When the surface roughness becomes large, darkening progresses and the color tone becomes darker. When the alloying degree of the plating film is 7% or less, the surface roughness is small and the surface roughness of the plating film is insufficient, so that sufficient darkness cannot be obtained. However, the alloying degree of the plating film is 13
If it exceeds%, the color tone will be darker, but the unevenness of the surface will be too large and the plating film will become brittle, and as a result, the powdering phenomenon will easily occur during processing. When the degree of alloying of the GA steel sheet used as the base material is 7 to 13%, the workability is not deteriorated, and preferably 50 ≦ L ^* ≦ 62, −
It is possible to obtain an appearance of a gray color tone defined by 1 ≦ a ^* ≦ 0 and −2 ≦ b ^* ≦ 0.

When the chromate film and the resin film are formed on the plated surface of the base GA steel sheet according to the present invention, the surface has a gray color tone, preferably within the above range.
It is only necessary that the gray tone has L ^* value, a ^* value, and b ^* value, and the meaning is not particularly limited.
However, as explained above, the alloying degree of G is 7 to 13%.
Since the above-mentioned color tone is generally obtained when the A steel sheet is used as the base material, the GA steel sheet having such an alloying degree may be used as the base material when the colored lubricated steel sheet of the present invention is manufactured. Since the higher the degree of alloying, the darker the color tone, the degree of alloying of the base GA steel sheet can be selected according to the desired color tone (darkness).

Since the alloying degree of the plating film of the GA steel sheet correlates with the surface roughness as described above, instead of the alloying degree,
It is also possible to select the base GA steel plate by using the plating surface roughness of the GA steel plate as a scale. Generally, the surface roughness of the plating film is preferably within the range of Ra = 0.5 to 2.0 μm. Since the larger the surface roughness within this range is, the darker the color tone is, it is possible to select the base GA steel sheet by the plating surface roughness so as to obtain a desired color tone. A more preferable surface roughness range is 0.8 to
It is 1.5 μm.

The amount of coating on the GA steel sheet is not particularly limited, but from the balance of corrosion resistance and workability, it is 30 to 30 per side.
A range of 60 g / m ² is preferred. As described above, the coloring of the colored and lubricated steel sheet of the present invention is not obtained by adding the coloring pigment in the resin film of the uppermost layer, so that it is not necessary to worry about the dispersibility and stability of the pigment, and the uniform It is possible to obtain a stable color tone. Moreover, since an expensive coloring pigment is not used, it is advantageous in terms of cost.

Chromate coating The chromate coating formed on the plating surface of alloyed hot-dip galvanizing (usually both sides, but may be one side) may be a known ordinary chromate coating, and a hexavalent chromium compound may be used. It is a film formed by being reduced to Cr ³⁺ and becoming insoluble. As the chromate treatment liquid, for example, an aqueous solution-type chromate treatment liquid containing a hexavalent chromium compound such as chromic anhydride, chromate salt, and dichromic acid as a main component, or a mixture of the above aqueous solution with colloidal silica is known. Any type of can be used, the treatment method is dipping,
Application, electrolysis, spraying, etc. are not particularly limited.

Particularly preferred as the chromate film is
A coating type chromate treatment liquid with excellent corrosion resistance, a partial reduction type that enables rapid film formation (part of Cr ⁶⁺ is Cr ³⁺
(Reduced to the above).
If necessary, heating is performed after the treatment to form a chromate film.

In the present invention, the amount of the chromate film deposited is in the range of 10 to 150 mg / m ² , preferably 30 to 90 mg / m ² in terms of metallic Cr. If the adhesion amount is less than 10 mg / m ² , sufficient corrosion resistance as an exterior cannot be exhibited. On the other hand, 15
If it exceeds 0 mg / m ² , the effect of improving the corrosion resistance with respect to the rate of increase of the adhered amount will be less, the surface appearance will be deteriorated, and the chromate film will become thicker, causing cohesive failure of the chromate film during press working. , The press formability decreases.

Lubricating Resin Film A substantially transparent lubricating resin film containing no pigment is formed on the chromate film. This resin film consists of a base resin (A) with silica particles (B) as SiO _{2 in an amount} of 5-30
% By weight, 0.5 to 30% by weight of a lubricating function-imparting agent (C), and 1 to 10% by weight of a basic alkali metal salt (D), and the adhesion amount is 0.1 to 5 g / m ² in dry film weight. . Each component (A) ~
Each of (D) may be used alone or in combination of two or more.

(A) Base resin: The base resin for the resin film is not particularly limited as long as it has a sufficient strength to withstand processing and can form a transparent film. Suitable resins include polyurethane resins, epoxy resins,
Acrylic resins, phenol resins, polyolefin resins, alkyd resins, melamine resins, polyvinyl butyral resins and the like can be mentioned.

(B) Silica particles: Silica particles are added to the resin film in order to improve the corrosion resistance of the lubricated steel sheet. The silica particles include colloidal silica (aqueous silica) such as Snowtex C to N (all manufactured by Nissan Chemical Co., Ltd.), and gas phase silica powder such as hydrophobic silica AEROSIL R-811 and hydrophilic silica AEROSIL 200V. Can also be used. An organic silicate that produces silica by hydrolysis (eg, ethyl silicate) is also a precursor of silica particles, but can be used in the present invention as silica particles. The average primary particle diameter of the silica particles is 5 to 100 nm, preferably 10 to 50 nm.
The range of is preferable.

The amount of silica particles in the resin coating is
O ₂ is in the range of 5 to 30% by weight, preferably 15 to 25% by weight. When silica is less than 5% by weight as SiO ₂ , the corrosion resistance is insufficient and it is difficult to apply it as an exterior. On the other hand, if it exceeds 30% by weight, the hardness of the resin film is increased, and mold galling occurs during molding, resulting in deterioration of press moldability. A small amount of a silane coupling agent may be used in combination with the silica particles in order to improve the adhesion between the resin and the silica particles.

(C) Lubricating function-imparting agent: As a lubricating function-imparting agent, a solid that exerts a lubricating (friction coefficient reduction) function (that is, generally known as a solid lubricant) and does not impair the transparency of the resin film. Use powder. For example, graphite blackens the coating and is not used in the present invention.

Lubricating function-imparting agents suitable for use in the present invention are powders of polyolefin wax and fluororesin, which are preferably in the form of fine powder having an average particle diameter of 5 μm or less. Since the mold temperature may reach close to 90 ° C during continuous processing, it is preferable to use a polyolefin wax with a softening point of 90 ° C or higher, especially 100 ° C or higher so that it will not soften during continuous processing. .

A particularly preferred polyolefin wax powder has an average particle size of 0.6 to 1.1 μm, a small particle size distribution width, a specific gravity (25 ° C.) of 0.95 to 0.98 and a softening point of 100 to 150 ° C.
Is a fine powder of a polyolefin-based polymer or copolymer such as polyethylene or polypropylene.

As the fluorine-based resin, tetrafluoroethylene resin (PTFE), trifluoroethylene chloride resin, vinylidene fluoride resin, vinyl fluoride resin ethylene / tetrafluoroethylene copolymer resin, tetrafluoroethylene / Examples include hexafluoropropylene copolymer resin. The average particle size of the fluororesin powder is preferably 0.1 to 5 μm, and particularly preferably 0.5 to 2 μm.

The lubricant function-imparting agent is present in the resin film in a proportion of 3 to 30% by weight. When this amount is less than 3% by weight, the lubricity is not improved so much, and when it exceeds 30% by weight, the adhesion to the substrate is lowered, the resin film strength is lowered, and the appearance is also deteriorated. The preferred blending amount of the lubricating function-imparting agent is in the range of 8 to 20% by weight.

(D) Basic Alkali Metal Salt The presence of a basic alkali metal salt in the resin film further improves the corrosion resistance of the lubricated steel sheet, particularly the corrosion resistance of the end faces and after working. That is, when performing severe processing or continuous processing, it is not possible to obtain sufficient corrosion resistance with the silica particle (B) component alone, and it is not possible to secure corrosion resistance on the end surface where the resin film is not formed, but basic By blending the alkali metal salt, such a problem is solved.

As the basic alkali metal salt, various basic alkali metal salts such as alkali metal hydroxides, carbonates, silicates, phosphates, borates and organic acid salts can be used. For example, hydroxides such as NaOH, KOH, LiOH, CsO
H and RbOH are carbonates such as NaHCO ₃ , Na ₂ CO ₃ and KHCO.
₃ , K ₂ CO ₃ , LiHCO _3, etc., and silicates such as sodium silicate (Na ₂ O.xSiO ₂ ), potassium silicate (K ₂ O.xSiO ₂ ), lithium silicate (Li ₂ O.xSiO ₂ ), etc. , As a phosphate, Na ₂ HPO ₄ ,
K ₂ HPO _{4 and the} like, and examples of the borate include NaBO ₂ and KBO ₂ . As the alkali metal silicate, for example, Na salt (sodium silicate) has an x value of 2 (No. 1), 2.5 (No. 2), 3 (3
No.) and the Li salt has an x value of 3.5 (lithium silicate 3
5), 4.5 (lithium silicate 45) and 7.5 (lithium silicate 5).

The reason why the addition of the basic alkali metal salt improves the corrosion resistance on the end surface and the corrosion resistance after processing is as follows.
Although it is not clear, this alkali metal salt exerts its function as an inhibitor, especially at a site where a corrosion factor such as an end surface or a fine flaw generated by processing easily enters, and blocks a corrosion factor such as Cl ^−. It is supposed that there is. By the addition of the basic alkali metal salt, the pH of the coating composition used for forming the resin film generally exhibits an alkalinity of 7.5 to 12.

The basic alkali metal salt is contained in the resin film at 1 to
It is contained at a rate of 10% by weight. If this amount is less than 1% by weight, the effect as an inhibitor as described above is small, and sufficient corrosion resistance cannot be obtained especially at the end face. On the other hand, if it exceeds 10% by weight, the resin film tends to gel, resulting in unevenness during coating, which not only deteriorates the quality of the appearance but also causes the coating film to become non-uniform. Corrosion resistance deteriorates. The preferable blending amount of the basic alkali metal salt is 3 to 7% by weight.

The lubricating resin film containing the components (B) to (D) in the base resin (A) is formed in an amount of 0.1 to 5 g / m ² as the dry film weight on one surface. This adhesion amount
When it is less than 0.1 g / m ² , the effect of improving the lubricity and corrosion resistance is small, and when it exceeds 5 g / m ² , the corrosion resistance is improved, but the press formability is lowered and the cost is increased. In particular, in order to obtain a good appearance even after processing, it is preferable that the adhesion amount is 1.0 g / m ² or more. A more preferable range of the adhesion amount is 2.0 to 4.0 g / m ²
Is.

The resin coating composition used for forming the resin film contains, in addition to the base resin (A), components (B) to (D) in an amount within the above-mentioned predetermined range based on the total amount of non-volatile components. . You may add additives, such as a crosslinking agent and a defoaming agent, to this coating composition as needed. The type of solvent is water,
Either alcohol or organic solvent may be used, and it is selected according to the resin species used. The coating method may be selected from various coating methods such as roll coating and curtain flow coating depending on the situation. The drying temperature of the coating film after painting is
Select according to the type of resin and solvent.

Thus, the colored and lubricated zinc-based plated steel sheet having the chromate film and the lubricating resin film formed on the alloyed hot-dip galvanized steel sheet has a gray color tone, and preferably L ^* a ^*. b ^* color system, 50 ≦ L ^* ≦ 62,
-1 ≦ a ^* ≦ 0, has a surface color that -2 ≦ b ^* ≦ 0. More preferably, 52 ≦ L ^* ≦ 56, −0.5 ≦ a ^* ≦ −
0.1, -0.5 <= b ^* <-0.1. This surface color is
Specifically, it is a calm gray color, and at first glance it looks like a painted steel sheet painted with gray paint (that is, it has a design property similar to that of a precoated steel sheet), and the metallic luster is substantially lost. .

Further, in the colored and lubricated zinc-based plated steel sheet of the present invention, the resin film of the uppermost layer exhibits a sufficient friction reducing effect, and continuous press forming or severe processing can be performed without applying lubricating oil. Moreover, the corrosion resistance after processing and on the end face is sufficiently high.

[0046]

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited to the examples.

A hot dip galvanized steel sheet (plate thickness 0.6 mm, double-sided plating, coating amount 45 g / m ² per side) produced in an existing hot-dip galvanizing line is changed in temperature and / or treatment time in a salt bath. Then, the steel sheets were dipped in and heat treated to produce GA steel sheets having different alloying degrees. A commercially available partial reduction coating type chromate treatment liquid was applied to one plating surface of each GA steel plate (300 × 200 mm) by a spin coater and dried at 80 ° C. for 30 seconds to form a chromate film. Next, on this chromate film, silica particles (colloidal silica with an average particle size of 20 nm) and polyethylene wax (average particle size of 1μ
m), and a basic alkali metal salt-free pigment-free clear resin coating composition are applied by a bar coater so as to have a predetermined adhesion amount, and dried at 120 ° C. for 30 seconds to form a resin film. Was formed to obtain a colored and lubricated GA steel sheet.

Table 1 shows the alloying degree (Fe%) and surface roughness (Ra value) of the plating film of the base GA steel sheet used, the amount of chromate film deposited, the base resin of the resin film, and the silica in the resin film. The content of particles and polyethylene wax, the type and amount of basic alkali metal salt, and the amount of resin film adhered are shown together.

Regarding the obtained colored and lubricated GA steel sheet,
The properties of color tone, corrosion resistance, post-processing corrosion resistance, and lubricity were examined in the following manner. [Test method] Color tone : Using a color difference meter (CR-300 manufactured by Minolta Co., Ltd.)
L ^* value, a ^* value, and b ^* value were measured. Corrosion resistance : Corrosion resistance was evaluated by the white rust occurrence time by a salt spray (SST) test (according to JIS Z-2371).

The end face corrosion resistance was measured by the above SST test.
The following criteria evaluated based on the measured value of the white rust generation width from the end surface of the test piece at the time of white rust generation. ◎: 1 mm or less ○: 1 to 3 mm △: 1 to 10 mm ×: 10 mm or more Corrosion resistance after processing : The test piece was subjected to 180 ° bending with a bending diameter of 10 mm, and then subjected to a salt spray test in the same manner as the corrosion resistance, The white rust generation time was examined.

Lubricity : Evaluated by the friction coefficient by the Bowden friction test and the press formability by the hat forming test with beads. Bowden friction test: Using the measuring device shown in Fig. 1 (a),
The friction coefficient was measured under the conditions of a load of 1 kg, a sliding speed of 4 mm / sec, and a sliding distance of 20 mm. Hat forming test with beads: Using a crank press with beads shown in FIG. 1 (b), 250 × 50 mm test pieces were deep-drawn into a hat shape. The bead height was 7 mm, the molding height was 43 mm, and the molding speed was 70 mm / sec. Observing the appearance of the ironing part of the molded product, ◎ (good, no change in appearance) →
The evaluation was made in four grades: ○ → △ → × (impossible, large galling, large powdering). The results of these tests are shown in Table 2.
Are shown together.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

As can be seen from Table 1, each of the lubricated steel sheets of the present invention exhibits a good gray color within the preferable color tone range, and exhibits corrosion resistance (including end face and post-processing corrosion resistance) and lubricity ( The friction coefficient and press formability) were also good. It was confirmed that the same results as in Table 1 were obtained when a fluororesin powder (eg, PTFE) was used instead of the polyethylene wax powder. On the other hand, in the comparative example including the condition (*) outside the scope of the present invention, at least one performance deteriorated.

In the colored lubricated zinc-plated steel sheet according to the present invention, the metallic luster of the GA steel sheet disappears even though the resin coating of the uppermost layer is a transparent coating containing no coloring pigment.
The appearance is a calm gray color, and it has the same design as pre-coated steel sheets. Therefore, since it can be applied as it is to automobiles, home electric appliances, building materials, etc., it is possible to significantly reduce the cost of these products.

Further, since it is excellent in lubricity and can sufficiently withstand extreme pressure during strong working and temperature rise of the die, it is possible to use a lubricating oil such as a press oil during the press working, It can be directly pressed. Therefore, it is possible to omit the press oil application work and the degreasing process for removing the press oil, which were conventionally performed by the customer, thereby reducing the cost and avoiding the use of harmful solvents such as trichloroethane. Therefore, it also leads to the prevention of environmental damage.

Further, since the steel sheet of the present invention is colored without using a pigment, the coloring is uniform and stable,
It is easy to apply the paint when forming the resin film, and it is inexpensive because no pigment is used. In addition, since the resin film is thin, desirable properties such as the weldability and press workability of the GA steel sheet are maintained, and high corrosion resistance can be exhibited even at the end face and after processing. As described above, the steel sheet of the present invention is suitable for being used as it is for the exterior, but of course, it may be coated and used.

[Brief description of drawings]

FIG. 1 shows an apparatus used for evaluation of lubricity in Examples,
FIG. 1 (a) is an explanatory view of a Bowden friction tester used for measuring a friction coefficient, and FIG. 1 (b) is an explanatory view showing a shape of a crank press in a hat forming test with beads.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // C10M 125/26 159/06

Claims (4)

[Claims] 1. The surface of the galvannealed steel sheet is coated with Cr
It has a chromate film having a converted adhesion amount of 10 to 150 mg / m ² and a resin film as an upper layer thereof, wherein the resin film is a silica resin (B) in the base resin (A).
5 to 30% by weight as SiO ₂ and 0.5 to the lubricating function imparting agent (C)
~ 30 wt%, and 1-10 basic alkali metal salt (D)
Weight content of dry film 0.1%
A colored and lubricated zinc-based plated steel sheet having excellent corrosion resistance on the end face, which is characterized by having a lubricating resin film of up to 5 g / m ² . 2. The surface color tone of JIS Z8729 is L ^* a ^* b ^*.
In color system, 50 ≦ L ^* ≦ 62, −1 ≦ a ^* ≦ 0, −2 ≦ b ^*
The colored and lubricated zinc-based plated steel sheet according to claim 1, wherein ≦ 0. 3. The colored lubricant according to claim 1, wherein the lubricating function-imparting agent (C) comprises a polyolefin wax having a softening point of 90 ° C. or higher and / or a fine powder of a fluororesin having an average particle size of 5 μm or less. Treated galvanized steel sheet. 4. A total of non-volatile components after chromate treatment of an alloyed hot-dip galvanized steel sheet with an alloying degree of 7 to 13% to form a chromate film with a Cr equivalent deposition amount of 10 to 150 mg / m ^{2 on} the plating surface. A resin coating composition containing 5 to 30% by weight of silica particles as SiO ₂ , 0.5 to 30% by weight of a lubricating function-imparting agent, and 1 to 10% by weight of a basic alkali metal salt, and containing no coloring pigment. A method for producing a colored lubricated zinc-plated steel sheet excellent in end face corrosion resistance, which comprises forming a resin film having a dry film weight of 0.1 to 5 g / m ² on a chromate film by using a material.