JPH0740503A - Lubricating resin treated steel panel excellent in press moldability, corrosion resistance and solvent resistance - Google Patents

Abstract

PURPOSE:To provide a surface-treated steel panel excellent in corrosion resistance, continuous moldability at the time of high speed press molding and solvent resistance. CONSTITUTION:Chromate films each containing vapor phase silica with an average particle size of 5-50nm in a wt. ratio (SiO2/Cr) of 0.1-5.0 with respect to total Cr are provided on both surfaces of a zinc plated steel panel, an aluminum plated steel panel or a cold rolled steel panel in an adhesion amt. of 10-200kg/m<2> per a single surface in terms of Cr and thermosetting resin films each having a resin compsn. consisting of 100wt.% of a resin having a hydroxyl group and/or a caboxyl group, 1-30wt.% of a curing agent, 1-20wt.% of polyolefin wax with an m.p. of 70 deg.C or higher and 10-80wt.% of silica and having a glass transition temp. (Tg) of -30 to 70 deg.C, are provided on both surfaces of the chromate films in an adhesion amt. of 0.1-3.0g/m<2> in terms of a dry wt. per a single surface.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a surface-treated steel sheet used for automobiles, home appliances, building material products, etc.
The present invention relates to a lubricating resin-treated steel sheet having excellent solvent resistance and corrosion resistance.

[0002]

2. Description of the Related Art Steel sheets used for automobiles, home appliances, building products, etc., especially plated steel sheets such as zinc or zinc-based alloy plated steel sheets, are used unpainted or painted. On the street, and in the meantime, it can be left unpainted for quite a long time. Therefore, there are problems that rust is generated during that period and that various substances are adsorbed and adhered to the surface of the plated steel sheet, resulting in poor adhesion of the coating.

Therefore, a chromate treatment is performed as a primary rust preventive treatment until the plated steel sheet is used by a consumer. However, the corrosion resistance of this chromate treatment is generally
It takes about 24 to 48 hours at most in the salt spray test, and 100 to 20 in the salt spray test even with the coating type chromate treatment which is a special chromate treatment containing silica sol.
Only 0 hours of corrosion resistance can be obtained. Therefore, products that are used in a severely corrosive environment for a long time have insufficient corrosion resistance.

Considering the case where the product is used in a severely corrosive environment, there is a method of preventing corrosion by applying a phosphate treatment instead of the chromate treatment and then applying a coating of about 20 μm thickness. However, when such a thick coating is applied, when the steel sheet is subjected to press working or the like, peeling or cracking of the coating film occurs, and local corrosion resistance is reduced at that portion. Further, with a coated plate, spot welding or the like becomes difficult or impossible, and therefore, it is necessary to remove the coating film in advance at the welded portion. Further, there is a problem that the thicker the coating film, the more paint is consumed, resulting in an increase in cost.

Therefore, it is desired to develop a surface-treated steel sheet which itself has excellent corrosion resistance without using a paint.

When press-forming a steel sheet,
Lubricating oil is applied to the surface of the steel sheet. Since this work involves a degreasing step, it is desired to develop a surface-treated steel sheet that can be pressed without the use of lubricating oil or the like during processing.

Further, when a consumer manufactures a product through various steps using a conventional surface-treated steel sheet, a stain such as a fingerprint adheres to the surface of the steel sheet due to the handling of an operator and the commercial value is increased. May significantly reduce. Therefore, it is desired to develop a surface-treated steel sheet that is less likely to be stained with fingerprints or the like during handling.

Against this background, as the prior art,
(1) A urethane-modified epoxy resin having a chromate coating on a zinc-based plated steel sheet, which further contains a composite aluminum phosphate, a chromium-based anticorrosive pigment, and a polyolefin wax, molybdenum disulfide, and silicone as a lubricant. Two-layer chromate-treated steel sheet having excellent corrosion resistance and lubricity (Japanese Patent Publication No. 62-24505) characterized by having 1 to 10 g / m ² layer, (2) having a chromate coating on a zinc-based plated steel sheet And an organic composite steel sheet excellent in cationic electrodeposition coating property, characterized by further having a urethane powdered epoxy ester resin layer containing silica powder, hydrophilic polyamide resin and polyethylene wax as a lubricant thereon in an amount of 0.3 to 5 μm. (JP-A-63-35798), (3) Chrome on a nickel-containing galvanized steel sheet consisting of a single γ-layer. Coating film containing iron phosphide as a conductive pigment, a polyolefin-based compound as a lubricant, a carboxylic acid ester-based compound, a polyalkylene glycol-based compound, and a coating resin thereon. A corrosion-resistant coating laminate (Japanese Patent Laid-Open No. 62-73938) is disclosed, which has a layer of 1 to 20 μm.

All of (1) to (3) have a lubricating resin coating containing a polyolefin compound as a lubricant on the chromate coating, and corrosion resistance,
A two-layer coated steel sheet with excellent lubricity.

[0010]

The lubricity of the two-layer type coated steel sheet in the above-mentioned prior art is determined by low speed press forming (up to 5).
mm / sec), but under the severe molding conditions in high-speed press molding (about 250 mm / sec) such as actual press, the sliding surface is at a high temperature (70 mm) during pressing.
(° C. or higher), the resin coating layer is easily peeled off, and the resin peeling powder adheres to the surface of the mold and the press-formed product, impairing the continuous formability and the appearance after processing. The continuous formability refers to the formability when the temperature of the mold is raised to about 120 ° C. depending on the conditions when about 1000 pieces are continuously formed at such a high speed.

Recently, this type of steel sheet has been attracting attention due to the necessity of chlorofluorocarbon regulation. For example, when sticking a seal for indicating chlorofluorocarbon regulation, handling precautions, etc., the surface is often cleaned by alcohol and various solvents. However, if the resin does not form a cured film, there is still a problem that the appearance is impaired.

It is an object of the present invention to solve the above-mentioned drawbacks of the prior art and to provide a surface-treated steel sheet which is excellent in corrosion resistance, continuous formability during high speed press forming, and solvent resistance. .

[0013]

As can be seen from the above-mentioned prior art, the press formability and corrosion resistance of Zn or Zn-based alloy-plated steel sheet can be obtained by forming a lubricating resin-based coating film after chromate treatment on the steel sheet surface. Can be improved.

The present inventors have made use of the advantages of these prior arts and, at the same time, have good press formability even under high-speed press forming, excellent solvent resistance, and flat plate, especially an organic resin film having good corrosion resistance in the processed part. As a result of extensive studies on the chromate coating, the present invention has been achieved.

That is, according to the present invention, vapor phase silica having an average particle diameter of 5 to 50 nm is contained on a zinc or zinc-based plated steel sheet in a weight ratio (SiO ₂ / Cr) of 0.1 to 5% with respect to total Cr.
0 has a chromate layer containing 0 to 200 mg / m ^{2 on} one side in terms of metallic Cr equivalent on both sides, and a resin mixture or composite having the following composition on the chromate coating and glass of the resin mixture or composite. Press moldability, which has a thermosetting resin coating film having a transition temperature (Tg) of −30 to 70 ° C. and an attached amount of 0.1 to 3.0 g / m ² on a dry weight basis on one side. The present invention provides a lubricating resin-treated steel sheet excellent in solvent resistance and corrosion resistance. (Composition of Resin Mixture or Composite) Resin Having Hydroxyl Group and / or Carboxyl Group 100 parts by weight Curing agent capable of reacting with the above resin 1 to 30 parts by weight Polyolefin wax having a melting point of 70 ° C. or higher 1 to 20 parts by weight Silica 10 to 10 80 parts by weight

[0016]

The following is a detailed description of the lubricating resin-treated steel sheet of the present invention, which is excellent in press formability, solvent resistance and corrosion resistance. Examples of the material of the lubricating resin-treated steel sheet targeted by the present invention include various galvanized steel sheets such as electrogalvanized steel sheet, electrogalvanized-nickel plated steel sheet, hot-dip galvanized steel sheet, 5% aluminum-zinc hot-dip galvanized steel sheet. You can

The chromate coating on the above steel sheet such as a zinc-based plated steel sheet may be an ordinary coating, for example, a treatment in which vapor phase silica is mixed with an aqueous solution containing chromic anhydride, chromate salt, dichromic acid, etc. as a main component. This is a chromium hydrate-based coating obtained by treating a liquid on a steel plate such as a zinc-based plated steel plate by a conventional method.

The gas phase silica to be added has an average particle size of 5 to 50 n.
It suffices to add 0.1 to 5.0 of m to the total Cr in a weight ratio (SiO ₂ / Cr), and all of them have the same performance. This is because if the addition amount is less than 0.1, the effect of improving the adhesion between the chromate layer and the resin layer cannot be expected.
If it exceeds 5.0, the coating strength will be high, and not only galling will occur during press molding but also the stability of the chromate solution itself will decrease. The average particle size of vapor phase silica is 5 to 5
The limitation to 0 nm is that dispersion is difficult if it is less than 5 nm.
This is because uniform adhesion between the chromate layer and the resin layer cannot be obtained, and when it exceeds 50 nm, galling is likely to occur during press molding.

Thus, the coating amount of the chromate solution to which the vapor phase silica is added is 10 to 200 m per one surface in terms of metallic Cr.
g / m ² is preferred. This is because if it is less than 10 mg / m ² , the adhesion between the steel sheet surface and the resin and the corrosion resistance are not sufficient. Further, even if it exceeds 200 mg / m ² , the effect of improving the corrosion resistance is small with respect to the increase in the amount of adhesion, and the deterioration of the treatment liquid is severe, the surface appearance is deteriorated, and the coating film becomes thick, so the press formability deteriorates. Because it does.

The lubricating resin-treated steel sheet having excellent corrosion resistance according to the present invention has an organic resin coating film having the following composition and adhesion amount on the chromate coating film.

That is, a resin having a hydroxyl group and / or a carboxyl group, 1 to 30 parts by weight of a curing agent capable of reacting with 100 parts by weight of the resin, and a polyolefin wax having a melting point of 70 ° C. or higher as a solid lubricant. 1 to 20 parts by weight, further 10 to 80 parts by weight of silica, and the glass transition temperature (Tg) of the resin mixture or composite is −.
The lubricating resin coating film has a temperature of 30 to 70 ° C. and a coating amount of 0.1 to 3.0 g / m ^{2 as} a dry weight on one side.

The base resin used in the lubricating resin mixture of the present invention is a resin having a hydroxyl group and / or a carboxyl group, and examples of such a resin include epoxy resin, alkyd resin, acrylic resin, urethane resin, polyester resin. , Polyvinyl butyral resin and the like. Examples of the curing agent capable of reacting with the base resin include phenol, melamine, isocyanate, amine and the like.

The utility of these resin / hardener combinations in the present invention lies in the following points. That is, the lubricating resin-treated steel sheet is formed by forming an inorganic-organic composite coating of silica-resin in order to improve corrosion resistance, but it is possible to form a highly corrosion-resistant coating by reacting with hydroxyl groups on the silica surface. This is because a hydroxyl group or a carboxyl group is desirable as the group.

Silica is added to improve the corrosion resistance of the lubricating resin-treated steel sheet. Colloidal silica, such as Snowtex-O and Snowtex-N (both manufactured by Nissan Chemical Co., Ltd.), organosilica sol, For example,
Ethyl cellosolve silica sol (manufactured by Nissan Chemical Co., Ltd.) and silica powder, for example, vapor phase silica powder (manufactured by Aerosil)
Etc., or an organic silicate such as ethyl silicate may be used. The particle size of the silica powder is preferably 5 to 70 nm.

A silane coupling agent may be used as a reaction accelerator for the base resin and silica. Examples of the silane coupling agent include γ- (2-aminoethyl) aminopropyltrimethoxysilane and γ-glycidoxypropyltrimethoxysilane.

However, in order to form a crosslinked coating film sufficient for improving the solvent resistance although a highly corrosion resistant coating film is formed by the reaction of the above silica and the base resin, phenol, melamine, isocyanate, amine are further added as curing agents. Etc. must be added in advance.

It is preferable but rather preferable to add general additives such as a reaction accelerator, a stabilizer, and a dispersant to the base resin as long as they do not impair the gist of the present invention.

Next, the lubricity imparting agent will be described. Generally, dry lubricants include wax, molybdenum disulfide, organic molybdenum, graphite, carbon fluoride,
Metal soap, boron nitride, fluororesin, and the like are known, and these are used as lubricants for bearings, or added to plastics, oils, greases, etc. to improve lubricity. Therefore, studies were conducted to obtain a resin-treated steel sheet having excellent lubricity using these lubricants.

As in the present invention, a resin-treated steel sheet having a high degree of lubricity which can be continuously formed without causing film peeling under severe press forming conditions involving heat generation in the sliding portion under high-speed press forming is obtained. For this purpose, a lubricant having a small friction coefficient and a high melting point is required to be uniformly present on the surface of the resin coating. In the steel sheet treated with such a coating, the lubricant on the surface of the resin coating on the steel sheet reduces friction with the die, prevents damage to the resin coating, and improves continuous formability.

The lubricant, the base resin, and the combination thereof which are suitable for the above purpose have been thoroughly studied. As in the present invention, under severe press molding conditions accompanied by heat generation of the sliding portion under high-speed press molding, in order to obtain a resin-treated steel sheet having high lubricity capable of continuous molding without causing film peeling, Generally, the glass transition temperature of the base resin is 70 ° C.
Although it must be as high as or higher, it has been found that a resin coating containing a lubricant having a small friction coefficient and protruding from the surface of the resin coating is also effective. By using such a lubricant, the lubricant absorbs the frictional impact with the mold, and the glass transition temperature of the base resin can be lowered.

However, when the base resin is a thermoplastic resin, when the wall temperature exceeds the glass transition temperature, the resin softens and peels off, and the continuous moldability is deteriorated, so an examination with a thermosetting type was tried. . In the thermoset resin film, even if the wall temperature during pressing exceeds the glass transition temperature, the resin does not extremely soften or flow, and the continuous moldability does not deteriorate.

As a result of earnest studies on a lubricant suitable for such a purpose, it was found that a polyolefin wax having an average particle size of 1 to 7 μm is suitable. The sliding surface becomes hot during high-speed press molding. At this time, the polyolefin wax works effectively as a lubricant. The polyolefin wax may be any wax as long as it is a wax made of a polymer of olefinic hydrocarbon such as polyethylene, polypropylene and polybutene, and these waxes may be used in combination.

Although various melting points of polyolefin wax are known, any one may be used as long as it has a melting point of 70 ° C. or higher. A low melting point and a high melting point may be used in combination, in which case the workability is further improved.

Next, the reasons for limiting the numerical values such as the film adhesion amount and the blending amount of the blending components will be described. Further, the compounding ingredients in the resin mixture or composite used in the present invention are preferably contained in the following proportions.

As a curing agent for making the base resin a thermosetting type, it is preferable to add 1 to 30 parts by weight to 100 parts by weight of the resin having a hydroxyl group and / or a carboxyl group. If it is less than 1 part by weight, it is not heat-cured, and if it exceeds 30 parts by weight, it is inferior in corrosion resistance and adhesion due to the unreacted curing agent.

Silica for improving the corrosion resistance is preferably added in an amount of 10 to 80 parts by weight with respect to 100 parts by weight of the resin having a hydroxyl group and / or a carboxyl group.
If it is less than 10 parts by weight, the effect of improving the corrosion resistance is small, and if it exceeds 80 parts by weight, the embrittlement of the coating film is increased and mold galling occurs at the time of molding to deteriorate the press moldability.

The addition amount of the lubricity-imparting agent depends on the hydroxyl group and /
Alternatively, 1.0 to 20 parts by weight of the polyolefin wax is desirable with respect to 100 parts by weight of the resin having a carboxyl group. If it is less than 1.0 part by weight, the effect of improving the lubricity is small and the press formability is poor, and if it exceeds 20 parts by weight, the strength of the resin film is lowered and the press work appearance is deteriorated. Also,
The polyolefin wax may be any wax as long as it has a melting point of 70 ° C. or higher and is made of a polymer of olefinic hydrocarbon. When the melting point is less than 70 ° C, the effect of improving continuous moldability under high-speed press molding is small.

It is preferable that the above-mentioned components are contained in the above-mentioned proportions, and the essential components such as the base resin and other additives are combined.

It is preferable to combine the essential components such as the base resin and other additives so that the glass transition temperature (Tg) of the above resin mixture or composite is -30 to 70 ° C. If the Tg is less than -30 ° C, the coating film is thermally decomposed and peeled off due to the temperature rise of the processed surface during high-speed press molding, and peeling resin powder is deposited, which deteriorates continuous moldability. Tg is 70 ° C
If it exceeds, the dynamic friction coefficient at around room temperature becomes extremely high and the press formability becomes poor. In addition, the continuous formability means the formability when the temperature of the mold is raised to about 120 ° C. depending on the conditions when forming continuously (about 1000 pieces) in actual operation at such a high speed. Say.

Further, the amount of such a lubricating resin coating adhered is preferably 0.1 to 3.0 g / m ^{2 as} dry weight on one side. If the adhesion amount is less than 0.1 g / m ² , the unevenness on the surface of the steel sheet cannot be completely filled, and the effect of improving corrosion resistance and pressability is small. On the other hand, if it exceeds 3 g / m ² , the corrosion resistance is improved, but the thicker the coating, the lower the press formability and the more economical.

Next, the method for producing a lubricating resin-treated steel sheet having excellent corrosion resistance according to the present invention will be described in detail. Examples of the material of the lubricating resin-treated steel sheet targeted by the present invention include various galvanized steel sheets such as electrogalvanized steel sheet, electrogalvanized-nickel plated steel sheet, hot-dip galvanized steel sheet, 5% aluminum-zinc hot-dip galvanized steel sheet. be able to.

In the production of the lubricating resin-treated steel sheet having excellent formability according to the present invention, the chromate treatment applied to the plated steel sheet may be carried out according to a usual treatment method, for example, chromic anhydride, chromate salt, and dichromic acid. You may form the coating film which consists mainly of chromium hydrate by performing the coating type chromate process etc. which apply | coats the processing liquid which mixed the vapor phase silica in the aqueous solution which made these etc. the main ingredients on a plated steel plate. After treating the plated steel sheet with a chromate treatment liquid, a chromate film is formed on both sides of the steel sheet through a step of squeezing with a flat rubber roll or the like and a drying step such as hot air drying.

Subsequently, an organic resin film made of the above-mentioned resin mixture or composite is formed on the above chromate film.
It is formed by the following method. Prepare a prescribed amount of each component,
Mix and disperse them to make them physically uniform. Next, preferably, a silane coupling agent is added and mixed and dispersed again to form a physically uniform resin mixture or composite. The resin mixture or the composite is applied to a predetermined thickness by a known ordinary method such as roll coating, spray coating, dip coating, and brush coating, and usually 50 to 1
It is usually dried at 80 ° C. for 3 to 90 seconds.

[0044]

EXAMPLES Next, the present invention will be described more specifically based on examples. (Example of the present invention) Under the following conditions, the test piece No. of the lubricating resin-treated steel sheet of the present invention was determined. 1 to 17 were produced. 1) Types of plated steel sheets A. Electrogalvanized steel sheet Thickness 0.8 mm Zinc coating amount 20 g / m ² B. Electrolytic zinc-nickel plated steel sheet 0.8 mm thickness Zinc-nickel plating adhesion amount 20 g / m ² Nickel content 12% C.I. Hot-dip galvanized steel sheet Plate thickness 0.8 mm Zinc coating amount 60 g / m ² 2) Chromate treatment CrO ₃ 20 g / L, Na ₃ AlF ₆ 4 g / L Chromate treatment liquid with composition of vapor phase silica (eg Nippon Aerosil Co., Ltd.) ) Was applied to a steel sheet and then baked. 3) Resin coating treatment The treatment liquid having the composition shown in Table 1 was applied on both sides by roll coating so that the dry weight on one side would be the adhesion amount shown in Table 1,
It was dried at 150 ° C. for 40 seconds to form a resin film. As the polyolefin wax, a polyethylene wax having an average diameter of 3 μm was used. The notes in the table are as follows. (Note 1) A: Polyurethane resin Tg = 20 ° C. B: Polyurethane resin Tg = −25 ° C. C: Epoxy-urethane resin Tg = 70 ° C. (Note 2) a: Blocked isocyanate (Desmodur APs manufactured by Sumitomo Bayer Urethane Co., Ltd.) Table) b: Methylated melamine (Cymel 303 manufactured by Mitsui Cyanamid Co., Ltd.) (Note 3) Silica powder manufactured by Aerosil (average particle size: 20 nm)

Comparative Example Chromate treatment was applied to each of the plated steel sheets in the same manner as in the present invention, and the treatment liquid having the composition shown in Table 1 was applied thereon so that the amount of adhesion shown in Table 1 was obtained. , A resin film is formed, and the test piece No. 18-33 was produced.

(Test / Evaluation Method) 1) Lubricity Test An uncoated oil test piece was processed with an Erichsen cup drawing tester while changing the drawing ratio, and the limiting drawing ratio was determined. In addition, the powdering resistance at that time was evaluated by collecting the peeling powder adhering to the die with a cellophane tape and from the degree thereof. Press conditions ・ Wrinkle pressing pressure 2 tons ・ Punch diameter 33 mmφ ・ Blank diameter 59 to 79 mmφ ・ Drawing speed 5 mm / sec, 500 mm / sec Evaluation criteria ◎: No die attached ○: Some die attached △: Some die attached ×: Die attached slightly ×: Die attached 2. Adhesiveness 2) Flat plate corrosion resistance test A salt spray test (JIS Z-2371) was performed, and the time required for the occurrence of white rust was evaluated. 3) Corrosion resistance test after processing An uncoated oil test piece was drawn under the following conditions with an Erichsen cup drawing tester, and a salt spray test (JIS Z-2371) was performed on the drawn surface of the cup. . The time required until the occurrence of white rust was evaluated. Press conditions ・ Wrinkle pressing pressure 2 tons ・ Punch diameter 33mmφ ・ Blank diameter 59mmφ ・ Squeezing ratio 1.78 ・ Squeezing speed 500mm / sec 4) Solvent resistance 1k with ethanol-impregnated gauze
Rubbing is performed by applying a pressure of g / cm ² , and the superiority or inferiority is evaluated by the number of times of reciprocation until a chromate surface appears.

Test piece No. prepared by the above method 1
~ 33, by the above method, lubricity, flat plate corrosion resistance,
After processing, corrosion resistance and solvent resistance were tested and evaluated. The results are shown in Table 2.
It was shown to. As is clear from Table 2, the lubricating resin-treated steel sheet of the present invention has excellent solvent resistance and good lubricity during high-speed press molding, and therefore, not only flat plate corrosion resistance but also corrosion resistance after processing is good. Is.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

[Table 3]

[0051]

[Table 4]

[0052]

[Table 5]

[0053]

[Table 6]

[0054]

[Table 7]

[0055]

[Table 8]

[0056]

[Table 9]

[0057]

According to the present invention, the corrosion resistance is excellent,
And because the lubricity during high-speed press molding is good,
There is an effect that it is possible to provide a lubricated resin-treated steel sheet that can be directly pressed without using a lubricating oil such as a press oil at the time of press working and is less likely to be stained with fingerprints or the like at the time of handling, and a manufacturing method thereof. In addition, there is an effect that a plated steel sheet with less rust can be obtained before the customer uses it. Further, in order to improve the lubricity during press working, there is an effect that it is possible to omit the lubricating oil application work and degreasing treatment which have been conventionally performed in the consumer, and therefore, there is an effect that the cost can be reduced. is there. Further, there is an effect that it is also excellent in resistance to various solvents such as alcohol when sticking various seals such as a global environment countermeasure seal and a handling caution seal, which accompany recent needs.

Claims (2)

[Claims] 1. A chromate layer containing 0.1 to 5.0 by weight ratio (SiO ₂ / Cr) of vapor phase silica having an average particle size of 5 to 50 nm on zinc or a zinc-based plated steel sheet. Adhesion amount is 10-200mg per side calculated as metallic Cr
/ M ² chromate coating on both sides, and a resin mixture or composite having the following composition on it, and the glass transition temperature (Tg) of the resin mixture or composite is −30 to 70 ° C. Dry weight per unit is 0.1 to 3.0 g / m
Press formability, characterized in that it comprises a thermosetting resin film which is ² to both surfaces, solvent resistance, lubricating resin-treated steel sheet excellent in corrosion resistance. (Composition of Resin Mixture or Composite) Resin Having Hydroxyl Group and / or Carboxyl Group 100 parts by weight Curing agent capable of reacting with the above resin 1 to 30 parts by weight Polyolefin wax having a melting point of 70 ° C. or higher 1 to 20 parts by weight Silica 10 to 10 80 parts by weight 2. The average particle size of the polyolefin wax is 1 to
The press formability and corrosion resistance according to claim 1, which is 7 μm.
Lubricant resin treated steel sheet with excellent solvent resistance.