JPH09323376A - Colored lubricatively treated steel sheet and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a weldable colored lubricatively treated steel sheet which has lubricity for enabling the press molding without the use of lubricant and is applicable as exterior cladding and further, is erosion-inhibitive on the end face and after the treatment and also is ornamental, and a resin solution containing pigment used for this steel sheet with a pot life free from gelation for at least, 30 days at 30 deg.C as high storage stability. SOLUTION: A chromate coat weighting 10-150mg/m<2> of deposit amount in terms of chromium and a lubricative resin coat of 1-6g/m<2> of dry coat weight are formed on the surface of cold-rolled steel sheet or galvanized or zinc alloy plated steel sheet. The lubricative resin coat contains 3-30 pts.wt. of polyethylene wax or fluororesin particle, 5-25 pts.wt. of alkali metal compound (e.g. lithium silicate) and 10-90 pts.wt. of colored pigment based on 100 pts.wt. of base resin but does not contain silica.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a surface appearance suitable for use as an exterior for automobiles, home electric appliances, building material products, etc., and presses such as drawing and bending without applying press oil. TECHNICAL FIELD The present invention relates to a colored and lubricated steel sheet excellent in corrosion resistance, which is capable of forming and has sufficient lubricity even in an end face portion and a processed portion, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Generally, when a steel sheet is processed by press forming or the like, press oil is applied to prevent damage to the steel sheet or press die due to insufficient slippage. The applied press oil is degreased in a degreasing step after processing. For this degreasing, an organic solvent such as specific CFC 1,1,1-trichloroethane has been used. Regarding the use of these specific halogenated organic solvents, a regulation protocol was adopted in Montreal in September 1987 in order to prevent the ozone layer from depleting any further, and in Japan, the national law was enacted in 1988 and the specified CFCs have already been released. It can no longer be used.

Therefore, a lubricated steel sheet having a resin film containing a lubricating component formed on the surface of the steel sheet in advance and capable of being processed without applying pressing oil has appeared. With this lubricated steel sheet, the press oil application-degreasing process can be omitted, the ozone layer can be prevented from depleting due to the use of CFCs during degreasing, and it is advantageous in terms of cost reduction by improving the environment of the press work workplace and simplifying the process. Therefore, the needs are increasing.

The following are examples of patent publications proposed for lubricated steel sheets. Japanese Patent Laid-Open No. 63-35798: A zinc-plated steel sheet is subjected to a chromate treatment, and then a urethane type epoxy ester resin, silica powder, a hydrophilic polyamide resin, and a polyethylene wax as a lubricant, which are solvent-based. An organic composite steel sheet excellent in cationic electrodeposition coating property, which is obtained by applying 0.3 to 5 μm of a coating composition.

Japanese Unexamined Patent Publication (Kokai) No. 2-124997: A chromate film is formed on a zinc alloy-plated steel sheet, and a film layer containing a composite or mixture of urethane resin and SiO ₂ as a main component is formed as an upper layer on the chromate film, and the chromate film is formed on the chromate film. 1-50% of fine silica particles
A lubricated steel sheet having a wax film contained therein.

Japanese Unexamined Patent Publication (Kokai) No. 3-96337: Chromate-treated electrogalvanized steel sheet with a resin coating containing a fluorine-based resin and silica fine particles in an acrylated epoxy resin. steel sheet.

JP-A-3-17190: A surface-treated steel sheet having excellent lubricity and corrosion resistance, which is obtained by coating a chromate-treated galvanized steel sheet with an emulsion paint of montan wax oxide containing fluorine-based resin particles and silica fine particles.

Japanese Unexamined Patent Publication (Kokai) No. 3-17189: A chromate-treated galvanized steel sheet is formed with a resin film containing fluorine-based resin particles and silica fine particles in a urethane-modified polyolefin-based resin, which is excellent in lubricity and corrosion resistance. Resin coated steel sheet.

JP-A-3-28380: Lubricity and corrosion resistance having a chromate film on a surface of a zinc-based electroplated steel sheet and a coating layer of a carboxylated polyethylene-based dispersion containing a fluororesin thereon. Excellent surface treated steel sheet.

Japanese Unexamined Patent Publication (Kokai) No. 3-16726: A chromate film and a resin film containing silica and a polyolefin wax in a resin having a hydroxyl group and / or a carboxyl group are formed on the surface of a zinc-based plated steel sheet.
Lubricant resin treated steel sheet with excellent formability.

[0011]

All of the lubricated steel sheets described above have lubricity capable of being processed without applying press oil, but their corrosion resistance is insufficient, and the end face portion and the processed portion cannot be processed. There is a problem that it is not possible to prevent the generation of rust.

An object of the present invention is to provide lubricity that can be processed without applying a press oil (thus, a degreasing step is unnecessary), and
It is an object of the present invention to provide a colored and lubricated steel sheet that has corrosion resistance and designability that enable application as an exterior, and that is also weldable.

Another object of the present invention is to have a colored resin film formed from a resin composition which is excellent in storage stability even if it contains a coloring pigment and can be stored for a long period of time without gelation. A colored lubricated steel sheet is provided.

[0014]

As seen in the above-mentioned prior art, after forming a chromate film, preferably on the surface of a steel sheet or a zinc-based plated steel sheet, silica and a lubrication component (lubrication function impartation) are contained in the resin. By forming a lubricating resin film containing an agent), it is possible to impart lubricity and a certain degree of corrosion resistance. However, its corrosion resistance is at a level insufficient to effectively prevent the generation of rust at the end face portion and the processed portion.

The inventors of the present invention have studied the means for ensuring the corrosion resistance of the resin film, especially the corrosion resistance of the end face portion and the processed portion while taking advantage of the advantages of the prior art. As a result, silica and a lubricating function imparting agent are contained in the resin film. It has been found that it is effective to add a small amount of an alkali metal compound in addition to the above, and if a pigment is further added, a colored lubricated steel sheet excellent in corrosion resistance and lubricity, which has a design property similar to that of a precoated steel sheet, can be obtained. .

However, when silica, an alkali metal compound and a pigment coexist in the resin liquid used for forming the resin film,
The stability of resin liquids, especially emulsion type aqueous resin liquids suitable for coating work in the plating line, deteriorates and gels during storage, and the usable life of the resin liquids is, for example, less than 15 days at 30 ° C. And turned out to be very short. When the storage stability of the resin liquid is low as described above, it is difficult to apply it to industrial production.

Then, as a result of further examination, even if silica, which has been generally considered necessary to be added in order to secure corrosion resistance, is not used, only an alkali metal compound is added to the resin, and the end face portion or the processed portion is simply added. It was found that sufficient corrosion resistance including the above can be secured. As a result, at least 30 ℃
It has become possible to obtain a colored lubricated steel sheet with good corrosion resistance, lubricity, designability, and weldability using a resin solution that can be stably stored for 30 days or longer.

In the present invention, a cold-rolled steel sheet or a zinc- or zinc-based alloy-plated steel sheet has a chromate film, preferably having a Cr equivalent of 10 to 150 mg / m ² , and a dry film weight of 1 A lubricated steel sheet having a lubricating resin film of up to 6 g / m ² , wherein the lubricating resin film is a base resin.
(A) 3 to 30 parts by weight of the lubricating function imparting agent (B) with respect to 100 parts by weight.
Excellent corrosion resistance, characterized by containing 5 to 25 parts by weight of an alkali metal compound (C) and 10 to 80 parts by weight of a coloring pigment (D), and being a silica-free colored resin film. It is a colored lubrication treated steel plate.

The colored and lubricated steel sheet of the present invention has the same lubricating performance as that of the above-mentioned conventional lubricated steel sheet (that is, it sufficiently withstands extreme pressure and die temperature rise during heavy working). Therefore, the press oil application-degreasing step can be omitted and the product can be directly processed. Further, sufficient corrosion resistance that can prevent rust generation at the end surface portion and the processed portion of the steel sheet is secured, and welding is also possible. Furthermore, by adding a pigment, it is possible to impart a desired color tone such as gray, black or brown, and it has excellent designability similar to that of a precoated steel sheet, and can be applied as an exterior.
In addition, since the resin liquid used to form the colored resin film does not contain silica, it has excellent storage stability even if it contains a relatively large amount of pigment, and can be stored for a long period of time, making it suitable for industrial production. ing.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The colored and lubricated steel sheet of the present invention will be described in detail below. Base material steel plate In the present invention, a cold rolled steel plate or a zinc or zinc-based alloy plated steel plate (hereinafter, these plated steel plates are collectively referred to as a zinc-based plated steel plate) is used as a base material. From the viewpoint of formability, it is desirable that the coating weight of the zinc-based plated steel sheet be 90 g / m ² or less per side.

The zinc-based plated steel sheet may be produced by any plating method such as hot dipping, electroplating, vapor phase plating (including vapor deposition plating, sputtering and the like). Zinc-based alloy-plated steel plates are Zn-Ni, Zn-
Al, Zn-Fe and the like are typical, but not limited to these, and any zinc alloy plating species containing Zn and containing one or more alloy elements may be used. For example, Zn−
Zn alloy plating containing a small amount of Zn, such as 55% Al-plated steel sheet, may be used. Further, a multi-layer plated steel sheet whose upper layer is a zinc-based plated layer can also be used as a base material.

One of the galvanized steel sheets suitable for use as a base material in the present invention is an alloyed hot-dip galvanized steel sheet (hereinafter abbreviated as GA steel sheet). GA steel sheet is formed by heat treating hot dip galvanized steel sheet after plating to diffuse Fe from the base material into Zn in the coating film to form the coating film.
It is a Zn-Fe alloy. The GA steel sheet more preferable as the base material has a degree of alloying (average Fe% in the plating film) of 7 to 13%, more preferably 9 to 11%, from the viewpoint of corrosion resistance and workability. The GA steel sheet tends to have larger irregularities on the plated surface and larger surface roughness as the alloying progresses and the alloying degree of the plating film increases. If necessary, skin pass rolling after alloying heat treatment
(Reduction ratio of 3% or less) can be performed to adjust the surface roughness.

When it is sufficient to provide only the chromate film lubricity, it is not necessary to form a chromate film as a lower layer of the lubricative resin film, but when corrosion resistance is required, cold rolling of the base material is required. It is preferable to first form a chromate film on the surface of the steel plate or the zinc-based plated steel plate.

In the chromate film, the hexavalent chromium compound is Cr
It is a film formed by being reduced to ³⁺ and being hardly soluble, and can be formed by using any conventionally known chromate treatment liquid (eg, coating type, reaction type, electrolytic type). The chromate treatment liquid to be used may contain colloidal silica and other known additive components in addition to the hexavalent chromium compound (eg, chromic acid anhydride, chromate salt, dichromate salt, etc.) as the main component. Good.

Particularly preferred as the chromate film is
A coating-type chromate treatment solution with excellent corrosion resistance, especially a partially reduced type that enables rapid film formation (a part of Cr ⁶⁺ is Cr ³⁺
(Reduced to the above). The application can be carried out by dipping, spraying or the like. If necessary, heating is performed after coating to form a chromate film.

In the present invention, the amount of chromate film deposited is
10 to 150 mg / m ^{2 in} terms of metal Cr, preferably 30 to 90 mg / m ²
Range. If the adhered amount is less than 10 mg / m ² , sufficient corrosion resistance cannot be exhibited for exterior purposes. Meanwhile, 15
When it exceeds 0 mg / m ² , the corrosion resistance improving effect is almost saturated, the surface appearance is deteriorated, and the thick chromate film easily causes cohesive failure of the chromate film during press working, resulting in poor press formability. .

[0027] surface of the cold-rolled steel sheet or galvanized steel sheet of the lubricating resin film base material, preferably after the formation of the chromate film as described above, to form the lubricating resin film. In the present invention, the lubricating resin film contains 3 to 30 parts by weight of the lubricating function-imparting agent (B) and 5 parts by weight of the alkali metal compound (C) with respect to 100 parts by weight of the base resin (A).
25 parts by weight, and coloring pigment (D) contains 10 to 80 parts by weight, the colored resin film without silica, the coating weight is 1 to 6 g / m ² on a dry film weight. Each component (A) ~
As (D), one or more kinds can be used. Further, this resin film can be formed on one side or both sides.

(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,
Examples thereof include acrylic resins, polyester resins, phenol resins, polyolefin resins, alkyd resins, melamine resins, polyvinyl butyral resins, and the like.

The base resin may be a solvent type resin dissolved in an organic solvent, but if possible, it is preferably an aqueous resin dissolved or dispersed (suspended or emulsified) in water, particularly an emulsion resin. As the water-based resin, commercially available products can be easily obtained from polyurethane, acrylic, polyester, and other resin types. Further, various compositions and manufacturing methods of the water-based resin are known, and the water-based resin can be prepared according to such known techniques. The preferred base resin in the present invention is an acrylic or urethane emulsion-based aqueous resin,
Acrylic water-based resin is particularly preferable.

(B) Lubrication function imparting agent: The lubrication function imparting agent is
Any solid powder that imparts a lubricating (friction coefficient reducing) function to the coating (that is, is generally known as a solid lubricant) and does not hinder the coloring of the resin coating may be used.

Lubricating function-imparting agents suitable for use in the present invention are, but are not limited to, polyolefin wax and / or fluororesin powder. The lubricating function-imparting agent (hereinafter, also simply referred to as wax) is preferably in the form of fine powder having an average particle size of 5 μm or less, for example 0.1 to 5 μm, more preferably 0.5 to 2 μm. If the average particle size is smaller than 0.1 μm, the effect of improving the lubricity is small relative to the wax content. Further, if the average particle size exceeds 5 μm, the protrusion rate of the wax from the resin film becomes large, and if the process with severe sliding is applied, the wax is peeled off and easily adheres to the mold. Occurs.

Since the mold temperature may reach close to 90 ° C. during continuous processing, the polyolefin wax has a softening point of 90 ° C. or higher, especially in order to prevent it from softening during continuous processing.
It is preferable to use one having a temperature of 100 ° C. or higher. A particularly preferred polyolefin wax powder has an average particle size of 0.6.
~ 3.0 μm, narrow particle size distribution and specific gravity (25 ℃) of 0.
It is a fine powder of an olefin polymer or copolymer such as polyethylene or polypropylene having a softening point of 95 to 0.98 and a softening point of 100 to 150 ° C.

Examples of the fluorine resin include tetrafluoroethylene resin (PTFE), trifluoroethylene chloride resin, vinylidene fluoride resin, vinyl fluoride resin, ethylene / tetrafluoroethylene copolymer resin, and tetrafluoroethylene. / Propylene hexafluoride copolymer resin and the like.

The lubricating function-imparting agent is used in the resin film in an amount of 100 parts by weight of the base resin (A) (herein, based on the solid content).
To 3 to 30 parts by weight. This amount is 3
If it is less than the weight part, the improvement of lubricity becomes insufficient. On the other hand, if this amount exceeds 30 parts by weight, the adhesion of the resin coating to the base material is lowered, the coating strength is lowered, and the appearance is also deteriorated. The preferred blending amount of the lubricating function-imparting agent is 5 to 25 parts by weight,
It is more preferably in the range of 8 to 20 parts by weight.

(C) Alkali Metal Compound The alkali metal compound is a component that contributes to the improvement of the corrosion resistance of the processed part and the cut end surface of the lubricated steel sheet. It is preferable that the alkali metal compound be basic. Examples of the alkali metal compound include hydroxides such as Li, Na, K, Rb, and Cs, carbonates (including hydrogen carbonate), silicates (M ₂ O · nSiO ₂ ), phosphates (hydrogen phosphate). Examples thereof include salts, pyrophosphates and the like), borates (including metaborates and the like), and the like.

As a specific example, NaOH, KOH, LiOH, CsOH,
Hydroxides such as RbOH; carbonates such as NaHCO ₃ , Na ₂ CO ₃ KHCO ₃ , LiHCO ₃ ; Na ₂ O ・ nSiO ₂ (sodium silicate), K ₂ O ・ nSiO
₂ (potassium silicate), silicates such as Li ₂ O ・ nSiO ₂ (lithium silicate); phosphates such as Na ₂ HPO ₄ and K ₂ HPO ₄ ; NaB
There are borates such as O ₂ and KBO ₂ .

A preferred alkali metal compound is lithium silicate (Li ₂ O.nSiO ₂ ) which has good compatibility with the pigment and has an effect of improving the dispersibility of the pigment in the resin liquid. Above all, n
Lithium silicate having a value of 3.5, 4.5 or 7.5 is preferred. It has been found that lithium silicate also has a large effect of improving the corrosion resistance. When the alkali metal compound is other than lithium silicate, it is preferable to use a resin having relatively high corrosion resistance, such as an acrylic resin, as the resin.

It is not clear why the addition of the alkali metal compound to the resin liquid improves the end face corrosion resistance and the post-working corrosion resistance, but especially at the end face and the site where the corrosive factors such as microscopic flaws generated during the work are likely to enter. alkali metal compound exerts the function as one inhibitor, Cl ^-
It is presumed that this is because it blocks corrosion factors such as.
Since the alkali metal compound has a high pH, the addition of the alkali metal compound causes the pH of the resin solution used for forming the resin film to generally have an alkalinity of 7.5 to 11.

The alkali metal compound is contained in the resin film in an amount of 5 to 25 parts by weight, preferably 10 to 25 parts by weight, based on 100 parts by weight of the base resin (A). If this amount is less than 5 parts by weight, the effect as an inhibitor as described above is small, and sufficient corrosion resistance cannot be obtained especially on the end face. On the other hand, if the amount exceeds 25 parts 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.

(D) Coloring Pigment A coloring pigment is contained in the resin film of the lubricated steel sheet of the present invention in order to completely conceal the color tone of the undercoat and to impart a colored appearance excellent in designability similar to that of a precoated steel sheet. Let The type of color pigment is not particularly limited as long as it has good dispersibility in the resin. For example, carbon black (CB), titanium oxide, iron oxide, phthalocyanine blue, phthalocyanine green,
One type or two or more types of organic red pigments are used, and the compounding ratio is changed to adjust to a gray type, a brown type, or any other desired color.

The amount of color pigment added is 100% of the base resin (A).
The amount is 10 to 80 parts by weight, preferably 20 to 60 parts by weight, based on parts by weight. If it exceeds 80 parts by weight, the ratio of the pigment exposed from the resin film increases, and the lubricity decreases. If the amount of the color pigment added is less than 10 parts by weight, the color tone of the base (cold rolled steel sheet or plated steel sheet of the base material, or chromate film) cannot be completely hidden, and the appearance deteriorates.

The components in the base resin (A) described above
(B) ~ (D), using a solvent, if necessary, by mixing so that the ratio of each component to 100 parts by weight of the solid content of the base resin (A) is within the above predetermined range, A resin liquid (resin composition) for forming a lubricious resin film is prepared. As described above, since the resin liquid does not contain silica, even if the emulsion type aqueous resin liquid contains a relatively large amount of pigment, gelation hardly occurs,
The resin liquid can be stably stored at 30 ° C. for 30 days or more.

The type of solvent may be water, alcohol or an organic solvent, and is selected according to the type of base resin used. As described above, it is preferable to use water as a solvent because the use of an organic solvent is avoided and the in-line coating directly connected to the plating line becomes easy.

If necessary, one or two kinds of various additives known to be added to the paint are added to the resin liquid.
More than one species can be added. Examples of such additives include a cross-linking agent, a defoaming agent, a rust preventive pigment, a pigment dispersant, a reaction accelerator, a leveling agent, and a thickener.

The resin solution is preferably applied to a chromate-treated cold rolled steel sheet or a zinc-based plated steel sheet and the coating film is dried to form a lubricating resin film, whereby the lubricated steel plate of the present invention is produced. . The coating method may be selected from various coating methods such as roll coating and curtain flow coating depending on the situation, and the drying temperature of the coating film after coating is selected according to the type of resin or solvent.

The coating is performed so that the amount of the lubricating resin film deposited after drying is 1 to 6 g / m ² , preferably ² to 4 g / m ² . If the amount of adhesion is less than 1 g / m ² , the effect of improving lubricity and corrosion resistance is small, and the base may not be completely covered even if a sufficient amount of pigment is added, especially the appearance after processing deteriorates. . If the adhesion amount exceeds 6 g / m ² , the corrosion resistance of the flat plate portion is improved, but the press formability is reduced and the cost is increased.

The lubricating resin film thus formed generally has a large dynamic storage elastic modulus (especially when a water-based resin is used), so that it can be applied to a die or a work material due to extreme pressure in strong processing or frictional heat in high-speed processing. Even if the temperature rises, the coating does not easily peel off, continuous molding is possible, and the appearance of the processed part can be maintained well. At the same time, since the alkali metal compound acts as an inhibitor, the corrosion resistance of the processed part and the end face is improved. In addition, the amount of the resin film attached is relatively small, and since it contains the alkali metal compound of the electrolyte, the resin film does not significantly impair the weldability,
The lubricated steel sheet of the present invention can be welded.

[0048]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples,% is% by weight unless otherwise specified. The materials used in the examples will be described first.

Base material steel sheet The base material steel sheet used is as follows (both have a thickness of 0.
8 mm). The symbols in parentheses are the ones used in Table 1.
The plated steel sheets are both double-sided plated steel sheets, and the adhesion amount is the amount per one side.

Cold-rolled steel sheet Hot-dip galvanized steel sheet (GI steel sheet) Adhesion amount 45g / m ² Electric Zn-12% Ni plated steel sheet (SZ steel sheet) Adhesion amount 20g / m ² Alloyed hot-dip Zn plated steel sheet (GA steel sheet) Adhesion amount 45g / m ² ,
Degree of alloying 9% Zn-5% Al plated steel plate (GF steel plate) Adhesion amount 45g / m ² Zn-55% Al plated steel plate (GL steel plate) Adhesion amount 45g / m ² Lubrication function imparting agent Polyethylene wax (softening temperature 100 ℃ , Average particle size 1μ
m).

Base Resin Acrylic-1: Kanebo NSC Co., Ltd., trade name "Iodozole 2D-423", acrylic emulsion, resin Tg
The point is about 105 ℃; Acrylic-2: Kanebo NSC Co., Ltd., trade name "Yodozol GD-900", acrylic emulsion, Tg of resin
The point is about 15 ° C. Urethane-1: manufactured by Dainippon Ink and Chemicals, Inc., trade name "HYDRAN HW-350", tolylene diisocyanate type hard type aromatic polyester polyurethane emulsion, solid content 30%, of resin Tg point (glass transition temperature) is about 11
0 ° C; Urethane-2: manufactured by Dainippon Ink and Chemicals, Inc., trade name "HYDRAN AP-60", isophorone diisocyanate type soft type polyester polyurethane emulsion, solid content 30%, Tg point of resin is about 30 ° C. .

Alkali metal compound Li-35 (lithium silicate in which n is 3.5 in the above formula) Li-45 (lithium silicate in which n is 4.5 in the above formula) Li-75 (lithium silicate in which n is 7.5 in the above formula) ) Na-2 (the above formula n is 2.5 sodium silicate in) Na-3 (sodium silicate n is 3 in the above formula) sodium hydrogen carbonate (NaHCO ₃₎ sodium hydroxide (NaOH) potassium hydroxide (KOH) .

Colored Pigment A water-dispersed pigment paste of the following four colors manufactured by Dainippon Ink and Chemicals, Inc. was blended in the following ratio to 100 parts by weight of the base resin to prepare a gray colored pigment paste. . DISPERSE HG-701 Titanium oxide 17.4 parts by weight DISPERSE HG-935 Carbon black 38.4 parts by weight DISPERSE HG-457 Yellow iron oxide 2.2 parts by weight DISPERSE HG-838 Red iron oxide 3.3 parts by weight.

[0054]

Example 1 A commercially available partial reduction coating type chromate treatment liquid was applied to both sides of the base steel sheet by a spin coater,
It dried at 30 degreeC for 30 second (s), and formed the chromate film. Then, a resin liquid prepared by mixing polyethylene wax as a lubricating function-imparting agent, an alkali metal compound, and a coloring pigment in the above-mentioned one or two kinds of base resin was applied to a bar coater on the chromate film on one surface. Was applied to obtain a predetermined dry film adhesion amount, and dried at 120 ° C. for 30 seconds to form a lubricating resin film, and a colored lubricated steel sheet was produced. The following test items were investigated for the obtained colored lubricated steel sheet and the resin liquid used.

Test Method (Storage Stability) The resin solution used for coating was stored at 30 ° C., the gelling state of the resin solution was observed, and the stability was evaluated according to the following criteria.

◎ ・ ・ ・ Stable for 60 days or more ○ ・ ・ ・ Gel in 30 to 59 days △ ・ ・ ・ Gel in 15 to 29 days × ・ ・ ・ Gel in less than 15 days (appearance) Visual inspection of the colored lubricated steel sheet It was observed and judged whether or not there was unevenness in color tone.

(End face corrosion resistance) A salt water spray (SST) test (according to JIS Z-2371) was performed for 500 hours on a test piece obtained by cutting a lubricated steel plate, and the white rust generation width from the end face after 500 hours The following criteria evaluated. ◎ ・ ・ ・ 1 mm or less △ ・ ・ ・ 3 to 10 mm ○ ・ ・ ・ 1 to 3 mm × ‥ 10 mm or more (corrosion resistance after processing) For the flat plate part, after sealing the back surface and end surface of a 75 mm × 150 mm test piece with polyester tape ,
It was subjected to a salt spray test (JIS Z-2371) and evaluated by 5% white rust occurrence time (time until white rust generation with an area ratio of 5%). As for the processed portion, the test piece was subjected to 180 ° bending with a bending diameter of 10 mm, and then the 5% white rust occurrence time in the salt spray test was evaluated as in the flat plate portion.

(Lubricity) Evaluation was made by the friction coefficient by the Bowden friction test and the press formability by the hat forming test with beads.

Bowden friction test: The friction coefficient was measured under the following conditions using the measuring device shown in FIG. 1 (a).

Load: 1 kg, sliding speed: 4 mm / sec, sliding distance: 20 mm.

Hat forming test with beads: Using a crank press with beads shown in FIG. 1 (b), a test piece (blank) was deep-drawn into a hat shape under the following conditions, and the appearance of the ironing part of the molded product was observed. Then, the evaluation was made according to the following four stages. Blank size: 250 x 50 mm Bead height: 7 mm Molding height: 43 mm Molding speed: 70 mm / sec [Evaluation] ◎ No change in appearance ○ Small scratches △ Large scratches × Large scratches, large powdering.

Symbol of base material used, amount of chromate film deposited, composition of base resin of resin film, blending amount of polyethylene wax, alkali metal compound and pigment in resin film (parts by weight relative to 100 parts by weight of base resin), Tables 1 to 3 show the types of alkali metal compounds and the amounts of the resin films attached together with the test results. The silica used in the comparative example is colloidal silica having an average particle size of 20 nm.

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

[Table 3]

[0066]

Example 2 A lubricated steel sheet was produced in the same manner as in Example 1 except that the chromate treatment was not performed. Table 4 shows the symbols of the base materials used, the composition of the base resin of the resin film, the amount of polyethylene wax, alkali metal compound and pigment in the resin film (parts by weight relative to 100 parts by weight of the base resin), type of alkali metal compound. , And the adhesion amount of the resin film are shown together with the test results other than the corrosion resistance.

[0067]

[Table 4]

As can be seen from Tables 1 to 3, the lubricated steel sheet of the present invention having a chromate film formed on the lower layer of the lubricous resin film has good lubricity (friction coefficient and press formability) and silica. Despite not containing, a comparative example containing silica and an alkali metal compound (Test No. 58,
Similar to 60), it shows excellent end face corrosion resistance and post-processing corrosion resistance.

Moreover, in this comparative example, since the storage stability of the resin liquid is extremely poor because the silica is contained, and the storage period is less than 15 days, the storage stability of the resin liquid is good according to the present invention. there were. However, at least one of the performances deteriorated in Comparative Examples in which the amount of the added component added to the resin liquid or the amount of the resin film attached was outside the range of the present invention.

From Table 4, it can be seen that even when the chromate film is not formed, a colored and lubricated steel sheet having good lubricity and uniform color tone can be obtained. Fluororesin powder (eg PTFE) instead of polyethylene wax powder
It was confirmed that the same results as those in Tables 1 to 4 were obtained when the above was used.

[0071]

As described above, the colored and lubricated steel sheet according to the present invention has excellent lubricity and can sufficiently withstand extreme pressure during strong working and temperature rise of the die. It is possible to perform the pressing as it is without using a lubricating oil such as a pressing oil during the pressing. Therefore, it is possible to omit the press oil application work and the degreasing process for removing the press oil, which have been conventionally performed by the customer, thereby reducing the cost and avoiding the use of a harmful solvent such as trichloroethane. Therefore, it helps to protect the global environment.

Further, the appearance has a calm color tone such as gray series or brown series depending on the added pigment, and has a design property similar to that of a precoated steel sheet. Therefore, since it can be applied to automobiles, home electric appliances, building materials, and the like for exterior use, the cost of these products can be significantly reduced. Moreover, since it does not contain silica, the coloring is uniform and stable, and the resin liquid can be stored for a long period of time, so that the coating operation can be easily carried out industrially. Furthermore, the thin resin film containing the alkali metal compound imparts high corrosion resistance to the end face and the processed part without impairing the weldability and press workability. The colored and lubricated steel sheet of the present invention is suitable for being used as it is as an exterior, but may be coated and used.

[Brief description of drawings]

FIG. 1 shows an apparatus used for evaluating lubricity in an example,
FIG. 1A is an explanatory view of a Bowden friction tester used for measuring a friction coefficient, and FIG. 1B is an explanatory view showing a shape of a crank press in a hat forming test with beads.

Claims (5)

[Claims] 1. A cold-rolled steel sheet or a zinc- or zinc-based alloy-plated steel sheet having a chromate coating with a Cr equivalent of 10 to 150 mg / m ² and a dry coating of 1 to 6 g / m ^{2 on} top of the chromate coating. And a lubricating resin film, wherein the lubricating resin film contains 3 to 30 parts by weight of the lubricating function imparting agent (B) and 5 to 5 parts of the alkali metal compound (C) with respect to 100 parts by weight of the base resin (A). 25 parts by weight and 10 parts of color pigment (D)
A colored and lubricated steel sheet having excellent corrosion resistance, which is a colored resin film containing up to 80 parts by weight and containing no silica. 2. A cold-rolled steel sheet or a surface of a zinc or zinc-based alloy plated steel sheet has a dry resin weight of 1 to 6 g / m ² of a lubricating resin film, and the lubricating resin film is a base resin (A). 3 to 30 parts by weight of the lubricant function-imparting agent (B), 5 to 25 parts by weight of the alkali metal compound (C), and 10 to 100 parts by weight of the coloring pigment (D).
A colored and lubricated steel sheet containing up to 80 parts by weight and not containing silica. 3. The colored lubricant according to claim 1, wherein the lubricant function-imparting agent (B) is a fine powder of polyolefin wax and / or fluorine resin having a softening point of 90 ° C. or higher and an average particle diameter of 5 μm or less. Treated steel plate. 4. The alkali metal compound (C) is Li ₂ O.nSiO.
The colored and lubricated steel sheet according to any one of claims 1 to 3, which is lithium silicate represented by ₂ (n is 3.5, 4.5 or 7.5). 5. A cold-rolled steel sheet, a zinc- or zinc-based alloy-plated steel sheet, or a Cr-equivalent deposition amount of 10 to the surface of these steel sheets.
On the surface of the steel sheet with a chromate film of 150 mg / m ² ,
100 parts by weight of base resin (A) and 3 parts of lubricating function imparting agent (B)
~ 30 parts by weight, 5 to 25 parts by weight of the alkali metal compound (C),
And a resin composition containing 10 to 80 parts by weight of a coloring pigment (D) and not containing silica, and a dry film weight of 1 to 6 g / m ²
Forming a colored resin film of the above.