JP2008069413A - Lubricant steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricant steel sheet having excellent formability by singly coating with only a water base coating agent for a lubricant film without performing chromate treatment. <P>SOLUTION: The lubricant steel sheet is composed of a steel sheet and a lubricant film formed at least on one side of the steel sheet. The steel sheet is a stainless steel sheet, a stainless steel-aluminum plated steel sheet or an aluminum plated steel sheet. The lubricant film is formed by coating a water base coating agent, so as to be dried. The water base coating agent comprises a resin, polyolefin wax and fluorozirconate, and also has a pH of 4.5 to 8. The resin includes a polyester resin, and the content of the polyester resin in the solid component in the water base coating agent is ≥70 mass%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lubricated steel sheet having excellent formability.

  In recent years, the application of stainless steel plates with excellent corrosion resistance has been spreading to home appliances, building materials, automobile parts, and the like. For example, as an automobile exhaust system material such as a muffler that requires strict corrosion resistance, a stainless-aluminum-plated steel sheet is developed in which a stainless steel sheet is subjected to aluminum plating to improve corrosion resistance.

  For these stainless steel plates and stainless-aluminum-plated steel plates, in order to produce automotive fuel tanks and oil supply pipes that require deep-drawing press work with severe workability, elongation at break and work hardening rate when processed by uniaxial tension Steel plates having excellent properties such as the Rankford value (r value) have been developed (see Patent Documents 1 and 2).

Thus, in deep drawing press working with severe workability, the conventional lubrication method using oil has poor lubricity, and the degree of processing is limited and its application is limited. In order to improve the lubricity, Patent Document 3 discloses a lubricated stainless steel plate and a lubricated stainless steel pipe coated with a lubricant film. The lubricated stainless steel sheet and the lubricated stainless steel pipe disclosed in Patent Document 3 are preliminarily applied as a lower layer of the lubricating paint to provide adhesion to the steel sheet and improve the wettability of the coated surface when the lubricating film is applied. A so-called chromate treatment is applied.
JP 2003-221660 A JP 2003-27792 A Japanese Patent Laid-Open No. 2001-140080

  However, as the chromate film, an electrolytic reduction chromate film mainly composed of trivalent chromium hydrated oxide is applied and an etching chromate liquid mainly composed of trivalent chromium and hexavalent chromium hydrated oxide is applied and dried. A wash-type coated chromate film is used. Since trivalent chromium and hexavalent chromium have a high environmental impact, and there is a social demand for reduction of environmentally hazardous substances, development of a steel sheet having a lubricating film that does not contain trivalent chromium or hexavalent chromium is desired. ing.

  The present invention has been made in view of the problems as described above, and its purpose is to perform lubrication with excellent molding processability by applying only an aqueous coating agent for a lubricating film without performing chromate treatment. It is to provide a steel sheet.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have determined that a predetermined aqueous coating agent, specifically, a resin containing a polyester resin, on a stainless steel plate, a stainless steel-aluminum steel plate, or an aluminum plating steel plate. And applying an aqueous coating agent containing polyolefin wax and fluorozirconate and having a pH of 4.5 to 8 and a polyester resin content in the solid content of 70% by mass or more, and drying. It has been found that the above problem can be solved by forming a lubricating film, and the present invention has been completed. More specifically, the present invention provides the following.

  (1) A lubricating steel plate comprising a steel plate and a lubricating film formed on at least one surface of the steel plate, wherein the steel plate is a stainless steel plate, a stainless-aluminum steel plate, or an aluminum plating steel plate, and the lubrication The film is formed by applying and drying an aqueous coating agent, and the aqueous coating agent contains a resin, a polyolefin wax, and a fluorozirconate salt, and has a pH of 4.5 to 8, and the resin. Is a lubricating steel plate containing a polyester resin, wherein the content of the polyester resin in the solid content of the aqueous coating agent is 70% by mass or more.

  (2) The lubricated steel sheet according to (1), wherein the resin further contains a polyurethane resin and / or a polyolefin resin.

(3) The lubricating steel sheet according to (1) or (2), wherein a dry film amount per one side of the lubricating film is 0.5 g / m ² or more and 4 g / m ² or less.

  (4) The content of the resin in the solid content of the aqueous coating agent is from 76% by mass to 98% by mass, and the content of the polyolefin wax in the solid content of the aqueous coating agent is 1.9. The content of the fluorozirconate in the solid content of the aqueous coating agent is from 0.1% by mass to 3.0% by mass (1) to (1) 3) The lubricated steel sheet according to any one of the above.

  (5) The lubricated steel sheet according to any one of (1) to (4), wherein the polyolefin wax is made of polyethylene particles having a particle size of 0.1 μm to 4 μm.

  (6) The lubricated steel sheet according to any one of (1) to (5), wherein the fluorozirconate is an ammonium fluorozirconate.

  The lubricated steel sheet according to the present invention has a lubricating film that can impart good lubricity on the surface of a stainless steel sheet, a stainless-aluminum plated steel sheet, or an aluminized steel sheet. This lubricating film is obtained by applying an aqueous coating agent and drying, and is not formed by reaction and precipitation by a dipping method using a strongly acidic treatment liquid. For this reason, the aqueous coating agent used for forming the lubricating coating of the present invention has a relatively high pH (4.5 or more and 8 or less). Further, the resin contains at least a polyester resin, a polyolefin wax, and a fluorozirconate, and the content of the polyester resin in the solid content is 70% by mass or more. And the lubricating steel plate which has a lubricating film excellent in process adhesiveness, slidability, and corrosion resistance by the effect | action of each of these components is obtained. That is, according to the present invention, it is possible to provide a single-layer lubricated steel sheet that does not require chromate treatment and has excellent lubricity.

  ADVANTAGE OF THE INVENTION According to this invention, the lubricated steel plate excellent in forming processability can be provided by apply | coating only the aqueous | water-based coating agent for lubricating films independently, without performing a chromate process.

  Hereinafter, embodiments of the present invention will be described in detail.

[Lubricated steel sheet]
The lubricated steel sheet according to the present embodiment includes a steel sheet and a lubricating film formed on the surface of the steel sheet.

[(Base material) Steel plate]
As the base steel plate, a stainless steel plate, a stainless-aluminum plated steel plate, or an aluminized steel plate is used.

[Pretreatment of base steel sheet (degreasing treatment)]
The base steel plate, stainless steel plate, stainless steel-aluminum steel plate, or aluminum plate steel plate is subjected to a cleaning process (degreasing process) to remove oil and dirt by alkaline degreasing, solvent washing, etc. before applying the aqueous coating agent. It is preferred that

[Stainless steel sheet]
The stainless steel plate that is the base steel plate (base material, basic material) of the lubricated steel plate according to this embodiment is iron or the like and alloy steel containing chromium or chromium and nickel. This stainless steel includes chromium-based stainless steel added with 10 to 30% by mass of chromium and nickel-based stainless steel added with 17 to 25% by mass of chromium and added with 5 to 20% by mass of nickel. is there.

[Stainless steel-aluminized steel sheet, aluminized steel sheet]
The stainless-aluminum-plated steel sheet and the aluminized steel sheet, which are the base steel sheets of the lubricated steel sheet according to the present embodiment, are the above-mentioned stainless steel sheet and Nippon Steel Technical Report No. 361 (1996) p. Aluminum plating is applied to a steel sheet mainly composed of iron with a chromium content of 5% or more added as shown in 52, or a steel sheet made of only iron. Examples of the form of the aluminum plating include Al-10% Si plating called type I or pure Al plating called type II, and the plating thickness is 10 to ²⁰⁰ g / m ² per side. .

[Lubrication film]
The lubricated steel sheet according to the present embodiment has a lubricating film formed on the surface of the steel sheet. The lubricating film is formed by applying and drying an aqueous coating agent.

[Aqueous coating agent]
The aqueous coating agent has a predetermined pH value and contains a resin, a polyolefin wax, and a fluorozirconate.

[PH of aqueous coating agent]
The pH of the aqueous coating agent is in the range of 4.5 or more and 8 or less. When the pH is less than 4.5, the dispersion stability of the polyester resin in the coating agent is lowered, and aggregates are generated or the whole is gelled. On the other hand, if it exceeds 8, the stability of the fluorozirconate is lowered, and a precipitate is easily generated. The pH is more preferably 5 or more and 7.5 or less.

[Resin contained in aqueous coating agent]
As content of resin in solid content of an aqueous coating agent, it is preferable that it is the range of 76 mass% or more and 98 mass% or less. When content is less than 76 mass%, the adhesiveness to a base steel plate falls and the film | membrane intensity | strength of the film | membrane formed falls. Furthermore, the polyolefin wax cannot be fixed to the film surface and inside. When the content exceeds 98% by mass, the lubricity is lowered and sufficient workability cannot be obtained. The content is more preferably in the range of 76% by mass to 90% by mass.

[Polyester resin]
The aqueous coating agent contains a polyester resin. The polyester resin has good adhesion to a stainless steel plate, a stainless-aluminum plated steel plate, or an aluminized steel plate, which is a base steel plate. Moreover, since the said polyester resin is large in film | membrane intensity | strength, drawing process adhesiveness is favorable and can also endure high degree process.

[Polyester resin content]
The content of the polyester resin in the solid content of the aqueous coating agent is 70% by mass or more. When the content of the polyester resin is less than 70% by mass, sufficient adhesion and drawing process adhesion cannot be obtained. The content of the polyester resin in the solid content of the aqueous coating agent is preferably 76% by mass or more and 90% by mass or less.

  Furthermore, the polyester resin can fix the polyolefin wax, which is a lubricating component, on the film surface and inside.

  Polyester resin is mainly composed of carbon, hydrogen, and oxygen, and since there is little decomposition into a substance with strong odor when pyrolyzed, the odor of gas generated by burning the film when welding a lubricating steel sheet is weak . On the other hand, for example, polyurethane resins contain nitrogen and generate nitrogen oxides during welding, and acrylic resins decompose into acid monomers during welding. Tend to emit. Thus, since the odor generated at the time of welding is weaker than that of other resin systems, the polyester resin can maintain a good working environment.

  The polyester resin is not particularly limited, and a normal polyester resin can be used as long as it is an aqueous polyester. Examples of such a polyester resin include water-soluble polyester resins and water-dispersed polyester resins, but those in a dispersion state are preferable.

  Moreover, what is marketed can also be used as it is as a polyester resin which can be contained in an aqueous coating agent and can improve the adhesiveness to a base steel plate. For example, “Eritel KZA-6034” (manufactured by Unitika), “Vironal MD-1100” (manufactured by Toyobo Co., Ltd.) and the like are commercially available polyester resins that can be contained in the aqueous coating agent. be able to.

[Molecular weight of polyester resin]
The number average molecular weight of the polyester resin is not particularly limited, but is preferably in the range of 5,000 to 100,000. If it is less than 5,000, the strength of the film is insufficient, and the film may be destroyed when the lubricating steel sheet is formed. On the other hand, when it exceeds 100,000, there is a risk of inhibiting film formation. The number average molecular weight is more preferably in the range of 5,000 or more and 30,000 or less.

[Glass transition temperature of polyester resin]
It is preferable that the glass transition temperature (Tg) of the said polyester resin exists in the range of 20 to 80 degreeC. When the glass transition temperature is less than 20 ° C., the hardness is insufficient, so that the film may be destroyed when the lubricating steel sheet is formed. On the other hand, if the glass transition temperature exceeds 80 ° C., the film-forming property may be deteriorated during the formation of the film, or the film may become too hard and become brittle. The glass transition temperature can be measured by a method well known to those skilled in the art. Moreover, when the said polyester resin is sold, the value described in the catalog etc. may be employ | adopted.

[Other resins]
In addition, when the performance of the film cannot be satisfied with the polyester resin alone, other resins and cross-linking agents may be blended in less than 30% by mass of the solid content of the aqueous coating agent. Since it becomes strong, it is not preferable. Examples of resins that can be blended include polyurethane resins, acrylic resins, polyolefin resins, phenol resins, epoxy resins, melamine resins, and the like, preferably polyurethane resins and polyolefin resins.

  Even if the polyester resin has a low molecular weight and the film strength is insufficient, the polyester resin film strength can be increased by using a crosslinking agent that can react with the carboxyl groups and hydroxyl groups of the polyester resin to polymerize the polyester resin. Thus, it is possible to provide a lubricated steel sheet in which the coating is not destroyed when forming. Although it does not specifically limit as said crosslinking agent, Specifically, a melamine resin, a polyfunctional epoxy compound, a phenol resin etc. can be mentioned.

[Polyolefin wax]
The polyolefin wax contained in the aqueous coating agent is important for reducing the coefficient of friction on the surface of the lubricating steel sheet and imparting lubricity. That is, the polyolefin wax can impart lubricity to the lubricated steel sheet and improve workability. Examples of the polyolefin wax include polyethylene wax, polypropylene wax, and polytetrafluoroethylene wax, and a polyethylene-based aqueous dispersion is preferable.

[Polyolefin wax content]
The polyolefin wax content in the solid content of the aqueous coating agent is preferably in the range of 1.9% by mass to 23.9% by mass. When the content is less than 1.9% by mass, the lubricity is lowered and the workability is lowered. When the content exceeds 23.9% by mass, the friction coefficient of the obtained film is too low and handling becomes difficult, and adhesion with the base metal is reduced. The content is more preferably in the range of 8% by mass to 22% by mass.

[Softening point of polyolefin wax]
The softening point of the polyolefin wax is preferably 100 ° C. or higher and 150 ° C. or lower. When the softening point is less than 100 ° C., it softens and melts during processing, and excellent properties as a solid lubricant additive are not exhibited. On the other hand, when the softening point exceeds 150 ° C., hard particles are present on the surface and the friction characteristics are lowered, so that good workability cannot be obtained.

[Particle diameter of polyolefin wax]
The particle diameter of the polyolefin wax is preferably 0.1 μm or more and 4 μm or less. If it is less than 0.1 μm, the effect of reducing the friction coefficient on the surface of the film cannot be sufficiently obtained, and the workability is not improved. When it exceeds 4 μm, it becomes a white powder state when it is formed into a film, and the wax is easily detached from the film, which is not preferable. The particle diameter is more preferably 0.5 μm or more and 3 μm or less. In the present specification, “particle diameter” means “average particle diameter” by the Coulter counter method. The average particle diameter can be measured using a commercially available Coulter counter. Moreover, when the said polyolefin wax is marketed, you may employ | adopt the value described in the catalog etc.

[Fluorozirconium salt]
The fluorozirconate contained in the aqueous coating agent acts on the surface of the base steel sheet and can improve adhesion and corrosion resistance. In particular, in an aluminum-plated steel sheet, the effect of improving adhesion and corrosion resistance is remarkable.

The fluorozirconate is not particularly limited, but tetrafluorozirconate is preferable. Examples of the tetrafluorozirconate include lithium, sodium, potassium, and ammonium salts (Li ₂ ZrF ₆ , Na ₂ ZrF ₆ , K ₂ ZrF ₆ , (NH ₄ ) ₂ ZrF ₆ ) of fluorozirconic acid. Can do. Of these, ammonium salts having high solubility in water are preferable.

[Content of fluorozirconate]
The content of the polyfluorozirconium salt in the solid content of the aqueous coating agent is preferably in the range of 0.1% by mass to 3.0% by mass. When the content is less than 0.1% by mass, adhesion and corrosion resistance are lowered. When the content exceeds 3.0% by mass, the stability of the aqueous coating agent is impaired. The content is more preferably in the range of 0.2% by mass or more and 2.0% by mass or less.

[Other ingredients]
The aqueous coating agent can contain a solvent, an antifoaming agent, a surface wetting agent, and the like for the purpose of improving workability during coating in addition to the above-described resin, polyolefin wax, and fluorozirconate.

  Since the aqueous coating agent is water-based, when a predetermined amount is applied to the base steel plate, the surface tension is higher than that of the solvent-based paint, so that the surface wettability is inferior and uniform coating properties may not be obtained. Therefore, it is preferable to add a surface wetting agent to the aqueous coating agent for the purpose of improving wettability. Examples of the surface wetting agent include known surfactants such as fluorine, silicon, glycol, and alcohol that reduce the surface tension.

[Application method of aqueous coating agent]
The method of applying the aqueous coating agent to a stainless steel plate, stainless-aluminum plated steel plate, or aluminum plated steel plate, which is a base steel plate, is not particularly limited. For example, roll coating, bar coating, curtain flow coating, Air spray, airless spray, etc. can be mentioned, but application by roll coating is preferred.

[Drying method of aqueous coating agent]
After the aqueous coating agent is applied, it is immediately dried to form a film. The drying method is not particularly limited, and examples thereof include general methods such as a hot air drying furnace, a direct-fired furnace, and an induction heating furnace. The ultimate temperature of the steel sheet is preferably 70 ° C. or higher and 300 ° C. or lower, and more preferably 100 ° C. or higher and 230 ° C. or lower. If it is less than 70 ° C., the film formation becomes incomplete and the film strength is reduced. If the temperature exceeds 300 ° C., the film components are likely to be thermally decomposed, causing the film to become brittle. In addition, when using a crosslinking agent, it is necessary to raise plate | board temperature to the temperature suitable for bridge | crosslinking.

[Dry film amount of lubricating film]
The amount of the dry film per one side of the lubricating film according to this embodiment is preferably in the range of 0.5 g / m ² or more and 4 g / m ² or less. If it is less than 0.5 g / m ² , a uniform film cannot be obtained, and good adhesion may not be obtained. On the other hand, if it exceeds 4 g / m ² , no further effect is obtained, which is economically disadvantageous. The dry film amount of the lubricating film is more preferably in the range of 0.7 g / m ² or more and 3 g / m ² or less.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited only to these Examples. Moreover, unless otherwise indicated, a compounding quantity represents a mass part.

Table 1 shows the trade names, manufacturers, and remarks (solid content, molecular weight, glass transition temperature (Tg)) of the polyester resin, polyurethane resin, polyolefin resin, and polyolefin wax blended in each Example and Comparative Example. Further, polyester resins, polyurethane resins, polyolefin resins, polyolefin waxes, lithium lithium zirconate (Li ₂ ZrF ₆ ), sodium fluorozirconate (Na) contained in the aqueous coating agent prepared for Examples and Comparative Examples ₂ ZrF ₆ ), fluorozirconic acid potassium salt (K ₂ ZrF ₆ ), and fluoro zirconate ammonium salt ((NH ₄ ) ₂ ZrF ₆ ) are shown in Table 2 and Table 3.

The base steel plate is a 0.6 mm thick Cr stainless steel SUH409 steel plate (11% Cr steel), a 0.8 mm thick Cr stainless steel SUS436L steel plate (17% Cr steel), and a 1.5 mm thick Ni stainless steel SUS304. Steel plate (18% Cr-8% Ni steel), 0.7 mm thick Ni-based stainless steel SUS316 steel plate (18% Cr-12% Ni-2.5% Mo steel), Al-10% Si on these stainless steel plates the per side 50 to 120 / ^{m 2} plating stainless - aluminum plated steel, low C steel further has per side 80 to 200 g / ^{m 2} plating Al is low C steel having a thickness of 1.4 mm - use of aluminum-plated steel sheet It was.

[Degreasing treatment]
Using a 2% aqueous solution of “Surf Cleaner 155 (trade name)” (manufactured by Nippon Paint Co., Ltd.) as an alkaline degreasing agent, the base steel plate was spray washed at 60 ° C. for 30 seconds and rinsed with deionized water.

[Coating process]
Before applying the base steel sheet, an aqueous coating agent was prepared. The coating conditions will be specifically described using Example 1. As shown in Tables 1 and 2, the polyester resin “Elitel KZA-6034 (trade name)” (manufactured by Unitika Ltd., solid content 30%, molecular weight 6,500, Tg 72 ° C.) and polyolefin wax “Chemical W-640” (Trade name) ”(polyethylene wax, manufactured by Mitsui Chemicals, polyethylene particles having a solid content of 40%, particle size of 1.0 μm), and (NH ₄ ) ₂ ZrF ₆ (manufactured by Stella Chemifa) as fluorozirconate % Aqueous solution was mixed, and the aqueous coating agent was adjusted so that the respective solid content mass% would be 79.0%, 20.0%, and 1.0%. The pH was 6.8. This adjusted aqueous coating agent was applied to a base steel sheet dried after degreasing using a bar coater. The aqueous coating agent was applied so that the dry film amount was 1.0 g / m ² . The dry coating amount of the lubricating coating was calculated from the weight loss before and after peeling and the test plate area by peeling off the obtained coating using methylene chloride (manufactured by Wako Pure Chemical Industries, Ltd.) as a peeling solution. Other examples and comparative examples were also tested based on the conditions shown in Table 1, Table 2, and Table 3.

[Drying process]
After applying the aqueous coating agent, it was immediately put in a hot air drying furnace having an atmospheric temperature of 500 ° C. and dried until the plate temperature reached 150 ° C. As soon as it reached 150 ° C., it was cooled with water and then dried. The back surface of the surface coated with the aqueous coating agent was coated and dried in the same procedure to obtain a test plate.

[Evaluation methods]
Processing adhesion, drawing adhesion, dynamic friction coefficient, and heating odor were evaluated (measured), and the results are shown in Tables 2 and 3. Each evaluation (measurement) was performed by the following method.

[Processing adhesion]
The steel plate surface coated with a lubricant film is pressed into a 30 mm diameter steel hole, and the steel plate is pushed into the hole with a 15 mm diameter steel ball centered on the axis of the steel hole. An overhanging process of 8 mm was performed, and the coating film peeling state at the tip of the convex portion was evaluated according to the following criteria. The evaluation results are shown in Tables 2 and 3.
◎: No peeling ○: Peeling area less than 5% Δ: Peeling area 5% or more ×: Peeling area 10% or more (reference area: 15 mm diameter circular area)

[Drawing adhesion]
The test piece is cut to a width of 30 mm, sandwiched with a jig with a length of 30 mm in the tensile direction, a draw bead test is performed at a tip radius of 2 mm, a molding height of 4 mm, a pressure load of 0.5 ton, and a drawing speed of 240 mm / min. Evaluation was made according to the following criteria. The evaluation results are shown in Tables 2 and 3.
A: Peeling area less than 5% B: Peeling area less than 10% Δ: Peeling area 10% or more ×: Peeling area 30% or more (reference area: 20 mm width × 100 mm)

[Dynamic friction coefficient]
A load of 1000 g was applied to a 12 mm diameter steel ball, the tensile speed on the surface of the test piece was 500 mm / min, the length was 50 mm, the number of times of sliding was 50 times, and the force required to pull the 50th steel ball was 1000 g. A value divided by the load was obtained, and this value was compared as a dynamic friction coefficient. The measurement results are shown in Tables 2 and 3.

[Odor when heated]
The steel plate was heated to 800 ° C., and the smoke and odor generated were judged according to the following evaluation criteria. The evaluation results are shown in Tables 2 and 3.
◎: weak odor ○: obvious odor △: pungent odor or bad odor ×: strong pungent odor or bad odor

  As shown in Tables 2 and 3, the lubricating film produced in this example gave good results with respect to work adhesion, drawing work adhesion, dynamic friction coefficient, and odor during heating. On the other hand, the performance of the lubricating film produced in the comparative example was not sufficient. Thus, it was confirmed that the lubricated steel sheet according to the present example was excellent in formability as compared with the lubricated steel sheet according to the comparative example.

Claims (6)

A lubricating steel plate composed of a steel plate and a lubricating film formed on at least one side of the steel plate,
The steel plate is a stainless steel plate, a stainless-aluminum plated steel plate, or an aluminum plated steel plate,
The lubricating film is formed by applying and drying an aqueous coating agent,
The aqueous coating agent contains a resin, a polyolefin wax, and a fluorozirconate salt, and has a pH of 4.5 or more and 8 or less,
The lubricating steel sheet, wherein the resin contains a polyester resin, and the content of the polyester resin in the solid content of the aqueous coating agent is 70% by mass or more.   The lubricated steel sheet according to claim 1, wherein the resin further includes a polyurethane resin and / or a polyolefin resin. 3. The lubricated steel sheet according to claim 1, wherein an amount of the dry film per one surface of the lubricating film is 0.5 g / m ² or more and 4 g / m ² or less. The content of the resin in the solid content of the aqueous coating agent is from 76% by mass to 98% by mass,
Content of the said polyolefin wax in solid content of the said aqueous coating agent is 1.9 mass% or more and 23.9 mass% or less,
The lubricating steel sheet according to any one of claims 1 to 3, wherein a content of the fluorozirconium salt in a solid content of the aqueous coating agent is 0.1 mass% or more and 3.0 mass% or less.   The lubricated steel sheet according to any one of claims 1 to 4, wherein the polyolefin wax comprises polyethylene particles having a particle diameter of 0.1 µm or more and 4 µm or less.   The lubricated steel sheet according to any one of claims 1 to 5, wherein the fluorozirconate is ammonium fluorozirconate.