JP2010018829A - Lubricated steel sheet and treatment liquid for forming lubricant film - Google Patents

Abstract

Rust rusting is prevented even when a long period of time elapses after a lubrication treatment and / or press processing is performed without additional lubrication treatment in a wet environment, and a stable lubricant film Thus, a lubricated steel sheet having good film-removability and good film removal and chemical conversion properties is provided.
A film-forming component comprising an alkali metal borate and / or alkali metal silicate (especially lithium silicate), a lubricating component comprising a mixture of zinc stearate and wax, oxygen of phosphate and vanadium. A lubricating film is formed on the surface of a steel sheet, particularly a steel strip, using a treatment liquid containing at least one rust preventive component selected from acid salts, oxyacid salts of molybdenum and mercapto compounds.
[Selection figure] None

Description

  The present invention is excellent in film removal after processing, and hence in chemical conversion treatment, and in addition to sufficient lubrication performance, has a rust preventive property, and a lubricating film excellent in stability over time of the film performance is a surface of the steel sheet. The present invention relates to a lubricated steel sheet formed on the surface and a treatment liquid for forming a lubricating film used for forming the lubricating film.

  In this specification, “steel plate” means to include “steel strip”. That is, “steel plate” means a steel plate in a narrow sense cut from a steel strip (including a cut steel plate and a steel plate blanked for press work) and a steel strip before being cut (eg, wound on a coil). Any form of steel strip taken) may be used.

  Regardless of hot-rolled steel sheets or cold-rolled steel sheets, recently, high-tensile steel sheets have been widely adopted for various applications in order to improve strength or reduce weight. Since a high-tensile steel plate is originally not sufficiently formable, mold seizure tends to occur when a high-tensile steel plate is formed. Therefore, it is required to take measures to improve the formability of the steel sheet and to prevent seizure of the mold.

  As a means for improving the formability of the steel sheet, for example, there is a method of applying an organic lubricating film typified by mill bond to the steel sheet surface. An organic lubricating film has a great effect of improving moldability, but since the thickness of the film is large, it is inevitable that press debris is generated due to peeling of the lubricating film during press working.

  The generated press dust has a problem that it contaminates the processed surface and causes surface defects. In particular, in precision equipment such as automotive torque converter parts, press debris, dirt, etc. remaining after processing can cause internal machine malfunctions and are not allowed.

  Further, steel plates for automobile bodies, particularly steel plates for vehicle outer layers, are required to have a beautiful appearance even after intense pressing. However, in the organic lubricating film such as the above-mentioned mill bond, the peeled debris becomes an indentation defect after press working, and the appearance quality after processing is significantly impaired. Therefore, the application of milbon could not be performed.

  From such a background, there has been a demand for processing steel sheets that can reduce press dust and ensure good formability. In response to this demand, several proposals have been made regarding a lubrication treatment in which a lubricant film based on an inorganic material is formed on a steel sheet surface as follows.

  Japanese Patent Application Laid-Open No. 2002-307613 (Patent Document 1) discloses a lithium silicate film as a lubricated steel sheet having excellent chemical conversion properties and formability. Specifically, the lithium content of the lithium silicate is Li / Si (atomic ratio) = 0.4 to 0.7, and the lubricant / lithium silicate mass ratio is 0.1 to 2.0. Good chemical conversion processability and moldability can be obtained.

  Japanese Unexamined Patent Publication No. 2000-309793 (Patent Document 2) discloses a combination treatment of “inorganic salt + metal soap + wax” as an aqueous lubricant for plastic working of a metal material after chemical conversion treatment.

  In JP-A-2004-99949 (Patent Document 3), the surface of the metal material for plastic working was selected from phosphate, sulfate, borate, silicate, molybdate and tungstate. After contacting at least one inorganic compound with an aqueous treatment liquid mainly composed of at least one lubricant selected from metal soap, wax, polytetrafluoroethylene, molybdenum disulfide and graphite, and drying, It is disclosed to form a two-layer lubricating film separated into a base layer mainly composed of the inorganic compound located on the interface side with the metal and a lubricant layer principally composed of the lubricant located on the surface side. .

  Lubricating films using these inorganic compounds as film forming components are not necessarily satisfactory. In particular, the mold galling resistance and the film removal property, which were good in the case of a mill bond which is an organic film, are insufficient. In applications where coating is applied after press processing, such as steel sheets for automobile bodies, after the press processing is finished, the lubricating film is removed by degreasing treatment, and after chemical conversion treatment such as zinc phosphate treatment is applied as a coating base treatment Painting is done. If the film removal property of the lubricating film at the time of degreasing is insufficient, the chemical conversion film formed in the chemical conversion treatment to be performed next becomes non-uniform, and a beautiful coating cannot be applied.

  The present applicants have disclosed alkali metal borates or lithium and lithium as a lubricated steel sheet capable of ensuring stable film removal and chemical conversion treatment, and exhibiting good press formability and mold galling resistance. Japanese Patent Application Laid-Open No. 2007-275706 (Patent Document 4) forms a lubricating film in which a lubricating component composed of a mixture of zinc stearate and a wax is contained in a film forming component composed of a mixture with silicate. And it proposed to Unexamined-Japanese-Patent No. 2006-240157 (patent document 5).

  The lubricated steel sheet needs to be transported, stored, etc. before being subjected to processing such as pressing, and rusting is a problem depending on the external environment. In order to improve the efficiency of press work, there has been a strong demand for steel materials that can be pressed as they are without pre-treatment such as bonde and bonderube to provide the high level of lubricity required for strict press work. Yes.

  The bonde-bonderube treatment is a treatment in which a zinc phosphate layer is formed by a chemical reaction and then a metal soap is applied, and a high level of lubricity that enables severe press working can be imparted to the steel sheet surface. However, the film formed by this treatment has high water absorption, and rust is likely to be generated when exposed to a humid environment for a long time. For this reason, Bonde-Bondalube processing is virtually impossible to store the processed steel sheet for a long time, so it is assumed that it will be applied in batch processing to the blanked steel sheet. It was causing a decrease in efficiency.

  Even if the stock is extended, if the rust preventive property of the lubricated steel sheet can be secured, the schedule can be made free, which is advantageous for the press operator because the degree of freedom of the work process is increased. Accordingly, there is a strong demand for a lubricated steel sheet that has rust prevention properties in addition to a high level of lubricity that can be subjected to severe pressing without pretreatment such as bonde-bonderube processing.

  In particular, in the case of a lubricated steel strip that has been subjected to a lubrication treatment that can be pressed directly on the steel strip before blanking, a very long time elapses from the manufacture and shipment to the press processing by the user. Having a lubricating film is essential. The organic lubrication treatment such as the above-mentioned mill bond also has a high water absorption of the film, its rust prevention property is insufficient, and is inferior to the steel plate coated with only the rust prevention oil. Therefore, when shipped as a steel strip that has been subjected to lubrication treatment, rust cannot be completely prevented depending on the external environment.

  In addition, even if it is not stored for a long time, it is said that the steel plates treated with bonde and bonderube are often subjected to press cracking during the rainy season, and there is a problem that pressability deteriorates in a short period in a humid atmosphere. . There is a strong demand for a lubricated steel sheet or steel strip that can ensure good rust prevention and exhibit stable lubricity even when the external environment during pressing changes.

  Japanese Patent Laid-Open No. 10-36876 (Patent Document 6) discloses a lubricant for plastic working of a metal material to which a rust preventive agent is added. Alkanolamine is exemplified as a rust preventive agent, but the rust preventive effect is manifested integrally with other film forming components and lubricating components, so that even if a known rust preventive component is added, the effect can be obtained. Can not. Moreover, it is necessary that the physical properties such as film removal property, chemical conversion property, and moldability are not inhibited by the rust preventive component, and it is necessary to consider that the above-described change with time is not caused.

In Patent Document 6, although the object is widely described as a lubricant composition and a lubricious metal material, it is substantially for wire drawing, and does not target the pressing of a steel plate or a steel strip. Since the physical properties required for the film are different between the wire drawing and the steel plate pressing, the composition for wire drawing cannot be directly applied to the pressing.
JP 2002-307613 A JP 2000-309793 A Japanese Patent Laid-Open No. 2004-99949 JP 2007-275706 A JP 2006-240157 A Japanese Patent Laid-Open No. 10-36876

  The present invention exhibits high lubricity that can be applied to severe press work as it is without pre-treatment such as bonde and bonderube treatment, and at the same time has good anti-rust properties, transportation and storage, etc. Rust generation is prevented even if the period is prolonged, and the lubrication treated steel sheet that can ensure stable breathability without deterioration of lubricity over time, and lubricity and rust prevention that can be used in its production Provided is a treatment solution for forming a lubricating film having excellent properties and stability over time.

  More specifically, the present invention has a film-removing property and a chemical conversion property required as a steel plate for an automobile body, and also has a rust prevention property in addition to a high formability necessary for press working of an automobile body. Lubricated hot-rolled and cold-rolled steel sheets, and a lubricating film forming treatment liquid for use in the production thereof are provided.

  According to the present invention, based on the lubricating film proposed in Patent Documents 4 and 5 and having good lubricity, mold galling resistance, film removal property, and chemical conversion treatment property, it contains a specific rust preventive component. By doing so, the above-mentioned problems can be solved.

  The present invention relates to a lubricated steel sheet in the form of a steel plate or steel strip provided with a lubricating film containing a lubricating component in the film forming component, wherein the film forming component is an alkali metal borate, an alkali metal A silicate or a mixture of both, wherein the lubricating component is a mixture of zinc stearate and wax, and the lubricating coating comprises phosphate, vanadium oxyacid salt, molybdenum oxyacid salt and mercapto compound It is a lubricated steel plate characterized by further containing at least one rust preventive component selected from:

  From another aspect, the present invention provides a film-forming component comprising an alkali metal borate, an alkali metal silicate, or a mixture of both, a lubricating component comprising a mixture of zinc stearate and wax, and a phosphate. And a rust preventive component comprising at least one rust selected from vanadium oxyacid salt, molybdenum oxyacid salt and mercapto compound.

Illustrative preferred embodiments of the invention are as follows:
The alkali metal silicate is lithium silicate;
The film-forming component is a mixture of an alkali metal borate and lithium silicate, the Li / Si atomic ratio of the lithium silicate is in the range of 0.5 to 4.0, and the alkali metal borate / The solid content mass ratio of the lithium silicate is 2/3 or more;
The rust preventive component is one or more selected from magnesium phosphate, ammonium phosphate, ammonium vanadate, ammonium molybdate tetrahydrate, and mercaptoethanol;
-The mass ratio of the solid content of the lubricating component / film-forming component is within the range of 0.1 to 2.0, and the mass ratio of zinc stearate / wax is within the range of 0.3 to 5.0, and is rust-proof. The mass ratio of component / film-forming component is in the range of 0.001 to 2.0.

In the lubricated steel sheet of the present invention, the total amount of the film forming component, the lubricating component, and the rust preventing component is preferably 10 to 1000 mg / m ² .
Moreover, the treatment liquid for forming a lubricating film of the present invention further contains at least one selected from polyacrylic acid and a nonionic surfactant as a dispersant, and / or has a pH in the range of 10 to 13. preferable.

  According to the present invention, a base steel plate is formed by forming a lubricating film on the surface of a steel plate using a treatment liquid comprising an alkali metal borate and / or silicate-zinc stearate-wax-specific antirust component. Lubrication with good film removal, chemical conversion, and formability of lubricating coatings required for automotive steel sheets that are coated after press forming, regardless of whether they are hot-rolled steel sheets or cold-rolled steel sheets A treated steel sheet can be manufactured.

  The obtained lubricated steel sheet exhibits excellent rust resistance characteristics that prevent rust generation even when transported or stored for a long period of time or in a wet environment. Accordingly, stable lubrication performance can be exhibited even after long-term storage or even when the environment during pressing is changed (for example, in an environment with high humidity). This can be realized by selecting a specific component as a rust preventive component to prevent deterioration of physical properties of the film such as lubricity and improving stability over time. When the rust preventive component is, for example, an alkanolamine disclosed in Patent Document 6 above, the stability over time of the lubricating coating is significantly reduced.

  Therefore, according to the present invention, by subjecting the steel strip to a lubrication treatment, it can be stored for a long time until press working, and stably exhibits a high degree of lubricity even if the usage environment changes. Lubricated steel sheets (steel strips) with good film removal properties and chemical conversion properties can be produced. This lubricated steel sheet can be subjected to severe press work such as for automobile bodies without blanking after pre-bending such as bonde and bonderube treatment after blanking, and the work efficiency of press work is remarkably improved. At the same time, the quality of the pressed product is stabilized because it can be stably pressed even under high humidity conditions.

  The base steel plate of the lubricated steel plate of the present invention is a steel plate of a wide range of steel types including not only high-strength steel but also general low-carbon, ultra-low-carbon soft steel, various alloy steels, etc. It can be selected according to the required performance. The base steel plate may be either a hot rolled steel plate or a cold rolled steel plate. Various surface-treated steel sheets such as zinc or zinc-based alloy plated steel sheets can also be used as the base steel sheet as long as improvement in workability is expected. However, since the lubricated steel sheet of the present invention can impart excellent press formability, a particularly excellent formability improving effect can be obtained when a high-strength steel sheet that is difficult to press form is used as a base steel sheet.

  As described above, the “steel plate” includes a steel strip. That is, the steel sheet includes any of a coiled or unrolled steel strip, a steel plate cut to a predetermined length from the steel strip, and a steel plate blanked into a predetermined shape by stamping before pressing. In order to make use of the excellent rust preventive ability exhibited by the lubricated steel sheet of the present invention and to increase the work efficiency of press working, the base steel sheet is preferably a steel strip.

  The use of the lubricated steel sheet of the present invention is intended for automobile structural materials such as an automobile body, but is not limited thereto, and the present invention can be applied to any steel sheet for press forming. In order to take advantage of the advantageous properties of the lubricated steel sheet of the present invention, applications requiring chemical conversion treatment and press formability are preferred.

  The lubricated steel sheet of the present invention is provided with a lubricating film in which a lubricating component and a rust preventive component are contained in a film forming component composed of an alkali metal borate and / or alkali silicate on the surface of a base steel sheet. The film forming component of the lubricating film does not substantially contain an organic resin such as an acrylic resin or a urethane resin that is contained as a film forming component in a conventional general lubricating film. That is, the film-forming component is substantially completely inorganic and consists essentially of an alkali metal borate, an alkali metal silicate, or both (a mixture thereof). However, if the amount is 10% by mass or less, preferably 5% by mass or less, more preferably 1% by mass or less of the film forming component based on the solid content, one or two of the other film forming components (organic or inorganic) are used. More than one species can coexist.

  As the alkali metal borate (hereinafter also simply referred to as borate) as a film forming component, potassium tetraborate, sodium tetraborate, and the like can be used, but are not limited thereto.

  On the other hand, sodium silicate, potassium silicate, lithium silicate (lithium silicate) and the like can be used as the alkali metal silicate (hereinafter, also simply referred to as silicate), and lithium silicate is particularly preferable.

  The combination of lithium silicate and a lubricating component forms a superior lubricating film that exhibits high lubricating performance, particularly high anti-galling resistance, with a thin film, and can suppress the occurrence of press debris. By using an alkali metal borate in combination with lithium silicate as a film forming component, the film removal property of the lubricating film is stabilized, for example, when using a degreasing liquid with reduced degreasing power, such as repeatedly used degreasing liquid In addition, since a good film-removing property can be obtained, the service life of the degreasing liquid is extended and the chemical conversion treatment property is stabilized. Furthermore, press formability is also improved. On the other hand, when the film-forming component is only an alkali metal borate, a film excellent in film removal property and chemical conversion treatment property can be obtained while ensuring sufficient moldability. Therefore, the film-forming component may be only borate, only silicate, or a mixture of both.

  A lithium silicate having a Li content such that the Li / Si atomic ratio is in the range of 0.5 to 4.0 is used. The Li / Si atomic ratio is preferably in the range of 0.8 to 3.0. The Li / Si atomic ratio of lithium silicate can be adjusted by mixing a plurality of commercially available lithium silicates having different Li / Si atomic ratios and / or adding lithium hydroxide.

  When the Li / Si atomic ratio of lithium silicate is less than 0.5, the film removal property and the chemical conversion property are deteriorated. Even if the Li / Si atomic ratio of lithium silicate is higher than 4.0, the film-removing property and the chemical conversion property are saturated, there is no further improvement, the moldability is lowered, and the stability of the treatment liquid is extremely high. To drop.

  When the alkali metal borate and the lithium silicate are used in combination, the amount of the borate is preferably set so that the mass ratio in the solid content of borate / lithium silicate is 2/3 or more. When this solid content mass ratio is less than 2/3, when using a degreasing solution having reduced degreasing power, the film removal property of the treatment film may be lowered, and the remaining film may cause a problem with chemical conversion treatment. . The solid content mass ratio of borate / lithium silicate is more preferably 3/2 or more and 4/1 or less.

  In order to ensure press formability, a lubricating component is included in the lubricating film. As a lubricating component, a mixture of wax and metal soap, in particular zinc stearate, is used. Many waxes have a relatively low melting point (melting point ≦ 130 ° C.), and the effect of improving moldability is particularly large in the temperature range from room temperature to the melting point of the wax. However, the lubricity at high temperatures (≧ 130 ° C.) at which die seizure during strong processing is likely to occur is insufficient.

  Such lubricity at high temperatures can be ensured by a metal soap. By using a metal soap zinc stearate and a wax together as a lubricating component, it is possible to ensure good lubricity and, therefore, moldability improvement effect in a wide temperature range.

  Films composed of a combination of alkali metal borates and / or alkali metal silicates and lubricating components (metal soap + wax) exhibit high lubrication performance, especially high anti-galling resistance, and form excellent lubricating films. , Generation of press debris can be suppressed. In this case, it was found that when the metal soap used as the lubricating component is zinc stearate, the film removal property of the lubricating film is remarkably improved as compared with the case where other metal soaps are used. As a result, for example, when a degreasing liquid having a reduced degreasing power such as a repeatedly used degreasing liquid is used, a good film-removing property is obtained. Turn into. Therefore, in the present invention, zinc stearate is used as the metal soap.

  Examples of the wax that can be used in the present invention include polyethylene wax, carnauba wax, paraffin wax, and fluororesin wax. Since borate and silicate as film-forming components are water-soluble and the treatment liquid is aqueous, a wax having good dispersibility or solubility in water is suitable. Specifically, water dispersible polyethylene wax, Teflon (registered trademark) wax, or a mixture thereof can be suitably used.

  As the metal soap, zinc stearate is used as described above. However, other metal soaps may be used in combination as long as the amount is smaller than that of zinc stearate. When another metal soap is used in combination, the amount of the other metal soap is preferably 30% by mass or less, more preferably 10% by mass or less, based on the total metal soap.

  Lubricating components affect not only moldability but also chemical conversion properties. For this reason, the amount of the lubricating component (the total amount of wax and zinc stearate) is preferably such that the mass ratio of the lubricating component / film forming component is 0.1 to 2.0, and this mass ratio is more preferable. Is 0.5 to 1.5. When the amount of the lubricating component is within this range, it is possible to ensure the formability and chemical conversion property of the lubricated steel sheet. When the mass ratio exceeds 2.0, the moldability improving effect is saturated, or rather, the moldability tends to deteriorate with the weakening of the film. On the other hand, if the mass ratio is less than 0.1, the moldability becomes insufficient.

  The mass ratio of zinc stearate / wax is preferably 0.3 to 5.0, more preferably 0.5 to 3.0. Within this range, lubricity at high temperatures can be improved when emphasis is placed on mold galling resistance.

  Regarding the influence of the lubricating component on the chemical conversion property, when the addition amount of the lubricating component is increased, the film removal property is improved, and thus the chemical conversion property is improved. Also from the viewpoint of securing chemical conversion properties, it is preferable that the mass ratio of the lubricating component / film forming component is 0.1 or more and the mass ratio of zinc stearate / wax is 0.3 or more.

  In addition, when using another metal soap together with zinc stearate, it is preferable to satisfy the above-mentioned mass ratio of zinc stearate even when the total amount of metal soap is substituted for zinc stearate.

  The present invention is characterized in that the lubricating film further contains a specific antirust component in addition to the lubricating component. In order to enable long-term storage of a steel strip on which a lubricating film is formed, the present inventors aim to form a lubricating film that does not deteriorate rust prevention over a long period of time and that does not deteriorate workability even in a wet atmosphere. Various antirust components were examined. As a result, by selecting a specific lubricating component, good long-term rust prevention and stable workability can be secured, and the basic performance of the lubricating film, such as film removal, chemical conversion and moldability, is not impaired. I found out.

  Rust preventive components that satisfy the above requirements in the case where the film forming component is an alkali metal borate and / or silicate, and the lubricating component is zinc stearate + wax are phosphates, vanadium oxyacid salts, molybdenum oxygen Mention may be made of acid salts and mercapto compounds. In this invention, 1 type, or 2 or more types selected from these as an antirust component is used.

  Examples of the phosphate include magnesium phosphate, ammonium phosphate, aluminum phosphate, zinc phosphate, sodium phosphate, potassium phosphate, and calcium phosphate. Magnesium phosphate and ammonium phosphate are particularly preferable. It is. The phosphate includes salts of condensed phosphoric acid such as tripolyphosphoric acid, metaphosphoric acid, and pyrophosphoric acid.

  Examples of vanadium oxyacid salts include ammonium vanadate, sodium vanadate, potassium vanadate, strontium vanadate, and sodium hydrogen vanadate. Particularly preferred is ammonium vanadate.

  Examples of molybdenum oxyacid salts include ammonium molybdate tetrahydrate, calcium molybdate, and sodium molybdate dihydrate. Although barium molybdate can be mentioned, ammonium molybdate is particularly preferred.

  A mercapto compound is a compound (generally an organic compound) having a thiol group (—SH). Examples suitable for use in the present invention include mercaptoethanol, mercaptosuccinic acid, mercaptoacetic acid, mercaptobenzimidazole, and mercaptobenzothiazole, with mercaptoethanol being particularly preferred.

  The amount of the rust preventive component is preferably such that the mass ratio of the rust preventive component / film-forming component is 0.001 to 2.0, and this mass ratio is more preferably 0.01 to 1.0. . When the amount of the rust preventive component is within this range, the film-removing property, chemical conversion property and formability of the lubricated steel plate are good, and long-term rust resistance can be ensured. If the mass ratio exceeds 2.0, the stability of the liquid may deteriorate and rust resistance may deteriorate. On the other hand, when the mass ratio is less than 0.001, rust resistance is not sufficient.

  When the lubricated steel sheet is stored or transported in a humid atmosphere, the characteristics of the lubricating film, particularly the lubricity, may deteriorate. The reason for this is not fully understood, but is due to the fact that the metal soap (zinc stearate in the present invention) applied to the lubricant has deliquescence as described below. It is estimated to be. That is, since metal soap having deliquescence absorbs water, the metal soap partially ionizes to change the strength of the film, or the steel plate corrodes with time in a wet state through metal soap having high water absorption. This is thought to be due to a decrease in adhesion at the interface between the film and the steel sheet.

  In the present invention, since it is premised on the application of metal soap for the purpose of achieving both high workability and chemical conversion treatment, it is preferable that stable formability can be maintained even in the presence of metal soap. Addition of a rust inhibitor is necessary. In order to maintain stable lubricating characteristics over time even in a humid atmosphere, it is necessary to select a special rust preventive component. Among the above, it has been found that the use of vanadium oxyacid salt and a mercapto compound is particularly preferable, and specifically, ammonium vanadate or mercaptoethanol is preferable. However, even with phosphates and molybdates, sufficient performance can be obtained by selecting the amount and the amount of the lubricating film.

  In addition to the above-mentioned components, the lubricating film has at least one component selected from polyacrylic acid and a nonionic surfactant as a dispersant for the purpose of improving the stability of the treatment liquid and the moldability of the lubricating film. Furthermore, it is preferable to contain. The preferred dispersant is polyacrylic acid (PA), but conventional nonionic surfactants such as polyoxyethylene ethers such as polyoxyethylene lauryl ether (POLE) can also be used.

  When using a dispersant selected from polyacrylic acid and a nonionic surfactant, the amount of the dispersant in the lubricating film (and thus in the total solid content of the treatment liquid) is 0.1 to 5% by mass, preferably 0.5 to 2% by mass. If the amount is less than 0.1% by mass, the intended effect cannot be sufficiently obtained. If the amount is more than 5% by mass, the content of other components is relatively reduced, which adversely affects the adhesion and formability of the lubricating film. May have an effect.

  The lubricated steel sheet of the present invention is produced by applying a lubricating film forming treatment liquid containing the above-described components in a suitable solvent (usually aqueous as described later) to the steel sheet surface and drying. That is, the treatment liquid for forming a lubricating film comprises an alkali metal borate and / or alkali metal silicate as a film forming component, a wax and zinc stearate as a lubricating component, the rust preventive component as described above, and optionally the above. Contains other ingredients such as dispersants.

  The total amount of the lubrication components is preferably such that the mass ratio of the lubrication component / film forming component is 0.1 to 2.0. The zinc stearate / wax mass ratio of the lubricating component is preferably 0.3 to 5.0. It is preferable that the total amount of the rust preventive component is an amount such that the mass ratio of the rust preventive component / film forming component is 0.001 to 2.0. A preferred film-forming component is a mixture of an alkali metal borate and lithium silicate, in which case the Li / Si atomic ratio of the lithium silicate is within the range of 0.5 to 4.0, and the alkali metal borate / lithium. The solid content mass ratio of the silicate is preferably 2/3 or more.

  The pH of the lubricating film forming treatment liquid affects the stability of the treatment liquid. In the present invention, the treatment solution pH is preferably 10-13. If the pH is less than 10, the solubility of the alkali metal borate is lowered and a precipitate is easily generated. When the pH is 13 or more, the dispersibility of the lubricant is lowered, and separation becomes easy.

  The lubricating film-forming treatment liquid of the present invention includes, for example, an aqueous solution of an alkali metal borate and / or alkali metal silicate and a polyacrylic acid as a dispersant and / or a nonionic surfactant (when used). Add lubricant component wax and metal soap, add one or more selected rust preventive components, stir well, and disperse lubricant component and rust preventive component in liquid Can be prepared. Therefore, the solvent of the treatment liquid is water, but a mixed solvent obtained by mixing a small amount of a water-miscible organic solvent (eg, alcohol) with water can also be used.

Adhering amount of lubricating film (total amount of film forming component, lubricating component and rust preventive component, that is, in the case of the present invention, alkali metal borate and / or alkali metal silicate, wax, zinc stearate, , the total amount of the rust preventive component) is preferably in the range of 10 to 1000 mg / m ^2, more preferred range is 100 to 500 mg / m ^2. When the adhesion amount is less than 10 mg / m ² , it becomes difficult to ensure moldability similar to that of a highly lubricating antirust oil. On the other hand, when the adhesion amount exceeds 1000 mg / m ² , the lubricating film becomes too thick and the film removal by alkali degreasing tends to be incomplete, and the chemical conversion treatment property may be deteriorated.

With regard to formability, if the adhesion amount of the lubricating film is 100 mg / m ² or more, the formability more than the mill bond excellent in formability can be secured, and if it is less than 500 mg / m ² , the chemical conversion treatment property equivalent to that of the cold-rolled steel sheet is obtained. It can be secured.

  The lubricating coating is preferably formed on both sides of the base steel plate, but may be formed only on one side depending on the application. Needless to say, the amount of adhesion is the amount of adhesion per one side.

  The method of applying the treatment liquid is not particularly limited as long as a predetermined amount of lubricating film can be formed. Specific application methods include spraying a treatment liquid and a shower ringer method in which the treatment liquid is squeezed with a roll, a roll coating method in which a coating is applied with a roll, and the drying after application of the treatment liquid. It is desirable to dry immediately after application. This is because uneven coating is likely to occur if not immediately dried. Drying after the treatment is sufficient if the film is dry and can be handled by hot air drying, but may be heated in a heating furnace. The drying temperature is not particularly limited, but is preferably a temperature lower than the melting point of the wax used.

  In the case where the steel plate is a steel strip, the lubricating film can be formed on the rolled steel strip as described above, and then wound around a coil and stored. That is, for example, a steel strip manufacturer can lubricate a steel strip by continuous processing rather than batch processing as after blanking. When the steel strip is a surface-treated steel strip such as a zinc or zinc-based alloy-plated steel strip, the surface treatment may be followed by a lubrication treatment. Since the lubricating film formed by the present invention has good blocking resistance, blocking of the lubricating film does not occur even when the lubricated steel sheet is stored in a coil or stacked state.

  The lubricated steel sheet according to the present invention can be subjected to press working as it is without blanking, if necessary, without pretreatment such as bonde-bonderube processing. However, oils such as general processing oils mainly composed of mineral oil, which are commonly used in press processing, or cleaning oils for the purpose of removing dirt and foreign matter on the steel sheet surface are applied before pressing (ie, oiling). May be.

  When coating is performed after the press work is finished, degreasing and chemical conversion are usually performed before coating. The lubricated steel sheet of the present invention is excellent in film removal properties, and the lubricating film is removed by ordinary degreasing treatment, so that the growth of chemical crystals is not hindered in the subsequent chemical conversion treatment, and a good chemical film excellent in uniformity is obtained. Can be formed, and therefore a good paint appearance is obtained.

  Add the wax, metal soap, rust preventive component and dispersant to the aqueous solution of potassium tetraborate and / or lithium silicate that will be the film forming component, stir well and disperse it uniformly. Prepared. For comparison, a treatment liquid for forming a lubricating film containing no rust preventive component was prepared.

  The composition of each treatment solution is summarized in Table 1. In the table, borate means potassium tetraborate, which is an alkali metal borate, and silicate means lithium silicate, which is an alkali metal silicate. If necessary, the pH of the treatment liquid was adjusted to pH 10 or 11 using lithium hydroxide or potassium hydroxide as the alkaline solution and sulfuric acid or nitric acid as the acid solution, respectively.

The waxes, metal soaps, anticorrosive components and dispersants used were as follows (in parentheses are symbols used in Table 1).
Wax: Water-soluble polyethylene wax (PE).

Metal soap: Zinc stearate (St-Zn), calcium stearate (St-Ca, for comparison) or sodium stearate (St-Na, for comparison).
Antirust component:
-Rust preventive component of invention examples: magnesium phosphate (P-Mg), ammonium phosphate (P-Am), ammonium vanadate (VA), ammonium molybdate tetrahydrate (MA), mercaptoethanol (ME);
Rust preventive component for comparison: benzotriazole (BT), triethanolamine (TA), sebacic acid dihydrazide (SH), aminopolyacrylamide (AP).

  Dispersant: polyacrylic acid (PA).

  As will be described below, this treatment liquid is roll-coated on one side of a predetermined steel plate determined for each test so as to have a selected adhesion amount, dried with hot air (plate temperature = 50 ° C.), and lubricated. A film was formed.

  The formed lubrication film or lubricated steel sheet was evaluated for chemical conversion treatment property, film removal property, formability, mold galling resistance, press haze resistance, and rust resistance. The stability of the lubricating film over time when the lubricated steel sheet was held in a wet state was evaluated by the variation of the friction coefficient using a pin-on-disk type abrasion friction tester.

The test methods and criteria for each test are as follows. These test results are summarized in Table 2.
(Chemical conversion processability)
Japan Steel Federation standard 590MPa high yield ratio cold rolled steel sheet JSC590R (thickness = 1.0mm) is used as the processing base plate (base steel plate), and a lubricated steel plate with a lubricating coating to be tested on one side of this steel plate is formed. It used for the processability test. The reason for adopting high-strength steel in this test is that high-strength steel sheets are originally inferior in chemical conversion properties compared to general mild steel.

  The lubricated steel sheet to be tested was immersed in a commercial degreasing solution FC-E2001 (manufactured by Nihon Parkerizing) adjusted to pH = 10 for 120 seconds, and then degreased by washing with spray. Subsequently, using the commercially available zinc phosphate chemical treatment solution PB-WL35 (manufactured by Nippon Parkerizing Co., Ltd.), phosphate chemical conversion treatment was performed under the specified conditions. The microscopic scale state of the crystal was observed by observing the appearance of the chemical conversion film formed on the lubricated surface of the test steel sheet and SEM observation (magnification: × 500 times) of the chemical crystal growth state.

Judgment Criteria Evaluation was made according to the following criteria based on the percentage of occurrence of the scale (%) obtained by SEM of the chemical conversion coating:
A: Less than 1%, ◯: 1 to 5%, Δ: 5 to 10%, ×: more than 10%;
In order to obtain a uniform coating appearance, it is required that the scale generation area ratio is 0% (that is, the evaluation is ◎).

(Film removal)
The lubricated steel sheet to be tested is subjected to alkaline degreasing and water washing (water temperature is room temperature) using the treatment liquid having pH = 10 as described above, and then left for 30 seconds, and then the water wetted area on the surface of the lubricated steel sheet. The rate was measured and evaluated according to the following criteria:
Judgment criteria Water-wetting area ratio of steel sheet ◎: 90% or more, ○: 80% or more, less than 90%, ×: less than 80%.

○ Above, it is evaluated that degreasing by degreasing is sufficient.
(Press formability)
Using a mild steel plate JSC270D (plate thickness = 0.8 mm) of the Japan Iron and Steel Federation standard as a treated original plate, a lubricated steel plate having a lubricating film to be tested on one side of this steel plate was prepared. After applying 2 g / m ² of general rust preventive oil to the lubricated surface of this test steel plate, a cylindrical deep drawing test was performed in the manner shown in FIG. 1 so that the lubricated surface was outside the cylinder. The evaluation criteria are as follows.

Judgment Criteria Evaluation was performed as follows by the molding limit wrinkle suppression pressure (kN).
＋+: 425 kN or more, ：: 375 kN (mill bond or more) or more, ○: 150 to 375 kN (high lubricating rust preventive oil or more), ×: less than 150 kN.

(Die galling resistance, press dust)
A 490 MPa class general-purpose hot-rolled steel sheet JSH440W (thickness = 3.2 mm) of the Japan Iron and Steel Federation standard was used as a processing original sheet, and a lubricated steel sheet having a lubricating film to be tested was formed on one side thereof. After applying 2 g / m ² of general rust preventive oil to the lubricated surface of this test steel plate, evaluation of die squeezing by crank press bending (bending so that the lubricated surface becomes the outer surface) was performed. The processing conditions and the evaluation method at that time were as shown in FIG. After five continuous sheets were formed at a clearance of -50%, the normal part remaining rate on the outer surface of the side wall part, which is the sliding part of the test, in the fifth sample was evaluated.

As a criterion for judgment, the remaining ratio of the normal part under the same conditions of mill bond (MC560J, coating amount = 1.2 g / m ² ) having good mold galling resistance is 75%. The one that did not occur was the best.

Processing conditions:
Sample size: 50 x 300 mm; clearance; -50%;
Number of moldings: 5 consecutive sheets Criteria for determining galling resistance:
Normal part remaining rate, A: 100%, B: 75-100% (mill bond or more), X: less than 75%.

  In addition, by observing the appearance of the processed side wall portion in the fifth sample after continuous molding, the occurrence of press debris at the sliding portion was evaluated. In the mold galling test, the lubricating film rubs and peels off, and the film builds up on the mold and reattaches to the steel sheet, so that press debris reattaches to the galling part, but it is a problem if it can be removed by steam degreasing. Judged to be none.

Criteria for press residue:
In the side wall appearance observation,
A: No blackening occurs due to press residue,
○: Blackening occurs due to press debris but can be removed by steam degreasing.
×: Blackening occurs due to press debris and cannot be removed by steam degreasing.

(Rust resistance)
Using a mild steel plate JSC270D (plate thickness = 0.8 mm) of the Japan Iron and Steel Federation standard as a treated original plate, a lubricated steel plate having a lubricating film to be tested on one side of this steel plate was prepared. After applying 2 g / m ² of general rust preventive oil to this test steel sheet, it was placed in a wet test machine at 50 ° C. and 90% relative humidity, and kept for 60 days while spraying water vapor. It was evaluated as follows.

Judgment criteria Red rust occurrence rate (%)
A: No occurrence of red rust, B: Less than 10%, B: 10% or more, less than 30%, X: 30% or more.

(Lubrication stability of lubricating film)
A lubricated steel plate (shape: 70 × 150 mm, original plate: mild steel plate JSC270D (plate thickness = 0.8 mm)) formed with a lubricating coating to be tested on one side is held for 7 days in a wet testing machine at 50 ° C. and 90% relative humidity. After that, the friction coefficient was measured using a pin-on-disk type abrasion friction tester (manufactured by Takachiho). The measurement conditions were 110 ° C., a load of 150 N, a test of up to 500 rpm under the conditions of 30 rpm, and an evaluation was made based on the number of revolutions until the friction coefficient increased to 0.2 or more.

Judgment criteria The number of revolutions until the friction coefficient increases to 0.2 or more,
A: More than 500 revolutions,
○: 200 times or more, less than 500 times,
Δ: 100 times or more, less than 200 times,
X: Less than 100 times.

  As shown in Table 2, the lubricated steel sheet (test Nos. 1 to 29) according to the present invention containing a specific antirust component in the lubricating film is excellent in performance balance and does not contain a rust inhibitor component. While maintaining film removal property, chemical conversion property, formability, and mold galling resistance equivalent to the lubricated steel plate of the example, rust resistance and stability over time of lubrication performance were remarkably improved. The reason why the stability of the lubricating film with time in Test No. 13 was low was that the content of the rust preventive component was small.

  According to the present invention, a steel plate in a steel strip state is preliminarily lubricated to produce a lubricated steel plate, and after storing it for a long period of time, even if the press processor performs blanking and pressing, Rust prevention and lubricity can be secured stably over time without performing conventional bonde / bonderube treatment. As a result, the work efficiency of press working and the degree of freedom of work are significantly improved.

  On the other hand, in Test Nos. 36 to 38 in which the lubricating film did not contain a rust preventive component, the rust resistance of the lubricating film and the stability over time of the lubricity were remarkably low. On the other hand, even if the lubricating film contains a rust-preventing component, in test Nos. 30 to 35 in which the rust-preventing component was outside the scope of the present invention, the rust resistance of the lubricating coating was still low. Lubricating stability over time did not improve at all compared to the case where no rust preventive component was contained. Also in Test No. 31, where the metal soap was other than zinc stearate, the stability over time of the lubricity was low. That is, it can be seen that the rust resistance and lubrication stability of the lubricating film of the present invention are achieved only by a specific combination of a film forming component, a lubricating component, and a rust preventing component.

It is a schematic diagram of the moldability evaluation method by cylindrical deep drawing. It is a schematic diagram which shows the evaluation test method and its measuring method of mold-proof galling resistance.

Claims (14)

  Lubricated steel sheet in the form of a steel plate or steel strip provided with a lubricating film containing a lubricating component in the film forming component, wherein the film forming component is an alkali metal borate, alkali metal silicate or A mixture of the two, the lubricating component is a mixture of zinc stearate and wax, and the lubricating coating is at least selected from phosphate, vanadium oxyacid salt, molybdenum oxyacid salt and mercapto compound A lubricated steel sheet characterized by further containing one kind of rust preventive component.   The lubricated steel sheet according to claim 1, wherein the alkali metal silicate is lithium silicate.   The film forming component is a mixture of an alkali metal borate and lithium silicate, the Li / Si atomic ratio of the lithium silicate is in the range of 0.5 to 4.0, and the alkali metal borate / lithium The lubricated steel sheet according to claim 1, wherein the solid content mass ratio of the silicate is 2/3 or more.   The rust preventive component is one or more selected from magnesium phosphate, ammonium phosphate, ammonium vanadate, ammonium molybdate tetrahydrate, and mercaptoethanol. Lubricated steel sheet as described in 1.   The solid content mass ratio of the lubricating component / film-forming component is in the range of 0.1 to 2.0, and the mass ratio of zinc stearate / wax is in the range of 0.3 to 5.0, and the rust preventive component / Lubricated steel sheet according to any one of claims 1 to 4, wherein the mass ratio of the film-forming component is in the range of 0.001 to 2.0. Film-forming component, the total amount of the lubricating component and anticorrosive component is 10 to 1000 mg / ^{m 2,} lubricated steel sheet according to claim 1.   The lubricated steel sheet according to any one of claims 1 to 6, wherein the steel sheet is a steel strip.   Film-forming component consisting of alkali metal borate, alkali metal silicate or a mixture of both, lubricating component consisting of a mixture of zinc stearate and wax, phosphate, vanadium oxyacid salt, molybdenum oxygen A treatment liquid for forming a lubricating film, comprising a rust-preventing component comprising at least one selected from acid salts and mercapto compounds.   The treatment liquid for forming a lubricating film according to claim 8, wherein the alkali metal silicate is lithium silicate.   The film forming component is a mixture of an alkali metal borate and lithium silicate, the Li / Si atomic ratio of the lithium silicate is in the range of 0.5 to 4.0, and the alkali metal borate / lithium The treatment liquid for forming a lubricating film according to claim 8, wherein the solid content mass ratio of the silicate is 2/3 or more.   The said rust preventive component is either 1 type (s) or 2 or more types chosen from magnesium phosphate, ammonium phosphate, ammonium vanadate, ammonium molybdate tetrahydrate, and mercaptoethanol, Any one of Claims 8-10. A treatment liquid for forming a lubricating film as described in 1.   The solid content mass ratio of the lubricating component / film-forming component is in the range of 0.1 to 2.0, and the mass ratio of zinc stearate / wax is in the range of 0.3 to 5.0, and the rust preventive component 12. The treatment liquid for forming a lubricating coating according to any one of claims 8 to 11, wherein the mass ratio of the coating forming component is in the range of 0.001 to 2.0.   The processing liquid for lubricating film formation in any one of Claims 8-12 which further contains at least 1 sort (s) chosen from polyacrylic acid and a nonionic surfactant as a dispersing agent.   The processing liquid for lubricating film formation in any one of Claims 8-13 whose pH is the range of 10-13.

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