JP2001064486A - Resin composition for steel plate coating use and steel plate and tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly corrosion-resistant steel plate exhibiting high inner surface corrosion resistance to a gasoline mixed with an alcohol, esp. methanol itself or formic acid formed by oxidation of methanol, and also exhibiting excellent press workability, seam weldability and outer surface corrosion resistance in tank manufacturing process using the steel plate. SOLUTION: This steel plate for highly corrosion-resistant tanks is obtained by providing one side of a steel plate with a metallic powder-contg. organic resin coating film comprising metallic Al powder and metallic Ni powder, an epoxidized diene-based block copolymer or amine-modified epoxidized diene- based block copolymer, and polyolefin wax and providing the other side with a silica-contg. organic resin coating film consisting mainly of an epoxidized diene-based block copolymer, silica and polyolefin wax.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly corrosion-resistant steel sheet, and more particularly to a resin composition which is excellent in corrosion resistance, press workability and seam weldability and is suitable as a tank material for gasoline containing alcohol or a mixture of alcohol and formic acid. The present invention relates to a steel plate using the same.

[0002]

2. Description of the Related Art In North America, Central and South America, and Europe, there are many countries in which energy policy is a national policy of reducing the oil dependence.
Alcohol (methanol, ethanol) itself or alcohol in gasoline
The introduction ratio of so-called gasohol mixed with 20% is increasing year by year.

[0003] However, these alcohols or gasohols (hereinafter referred to as “alcohol-based fuels”) are more likely to contain (a) water than ordinary gasoline fuels, and (b)
Separates layers by increasing the amount of mixed water and lowering the temperature. (C)
The alcohol may be oxidatively degraded to produce an organic acid (for example, it changes to formic acid in the case of methanol and acetic acid in the case of ethanol). (D) Turn (Pb / Sn alloy) plated steel sheet, which is the mainstream of the current tank material, is used for normal gasoline fuel, such as the plating layer being dissolved by a mixture of alcohol and gasoline containing 40% or more of methanol. It has the feature that it is more strongly corroded.

[0004] However, the tank of the automobile is one of the various parts constituting the automobile JP-A-10-235787.
It is positioned as the most important part in terms of ensuring safety.There is no defect in the seam weld, no holes are formed on the inside and outside of the tank due to corrosion, and the filter is clogged in the fuel circulation system. It is required that no significant floating corrosion products are generated.

At present, ordinary tank materials for automobiles include, for example, Pb-Sn alloy hot-dip coated steel sheet as disclosed in Japanese Patent Publication No. 57-61833, and Japanese Patent Publication No.
Japanese Patent Application Laid-Open No. 19981 discloses a Zn-plated steel sheet which has been subjected to a thick chromate treatment.

[0006] The corrosion resistance of these conventional materials to gasoline and alcohol fuels (hereinafter referred to as "inner corrosion resistance")
In view of the above, the Pb-Sn alloy has a disadvantage that it is very easily dissolved in methanol, and it is considered that practical use is difficult for methanol-mixed gasoline. On the other hand, electricity Z
The inner corrosion resistance of a material obtained by subjecting an n-plated steel sheet to a thick chromate treatment suppresses the occurrence of slight red rust and perforation due to the sacrificial corrosion prevention effect of Zn. However, the elution rate of Zn is high, a large amount of floating white precipitate is generated, and the filter is clogged in the fuel circulation system. Further, after the Zn is eluted, the base steel has a disadvantage that red rust and perforation are apt to occur, and is insufficient as a steel plate for a tank.

[0007] Instead of the above-mentioned electro-zinc plated steel sheet, Zn
Alloy-plated steel sheet mainly containing, for example,
No. 110791 discloses a Zn-Ni alloy-plated steel sheet, and Zn-C disclosed in Japanese Patent Publication No. 57-33347.
o alloy-plated steel sheet, Zn-Fe alloy-plated steel sheet disclosed in JP-B-57-61831, JP-B-54-332
No. 22, Zn-Al-alloy plated steel sheet, and JP-A-57-70288, Zn-Ni-Cr
In the case of using an alloy-plated steel sheet and a Zn-Co-Ni alloy-plated steel sheet disclosed in Japanese Patent Publication No. 57-33347, the dissolution rate of each of the alloy plating layers is considerably suppressed as compared with the Zn plating layer. Corrosion is suppressed on both outer surfaces. However, it still cannot solve the problem of filter clogging and hole corrosion due to perforated corrosion on the outer surface of the tank or floating white precipitate on the inner surface of the tank.

Therefore, in order to solve the above-mentioned drawbacks, excellent internal corrosion resistance is exhibited for alcohol alone or alcohol-mixed gasoline, particularly gasoline in which highly corrosive alcohol and formic acid are mixed, and the outer surface of the tank is exposed to the external environment. High corrosion resistance tank steel sheets that exhibit excellent corrosion resistance (hereinafter referred to as “corrosion resistance to the external environment” as “outside corrosion resistance”), and also exhibit excellent press workability and resistance weldability in the tank manufacturing process -18981, JP-B-2-18982 and JP-B-3-25349
No., published in Japanese Unexamined Patent Publication No. Japanese Patent Publication No. 2-18981 describes a steel plate having a metal plating layer containing a Pb / Sn alloy or Sn as a main component and an organic resin film containing a metal powder as an upper layer. JP-B-2-18982 and JP-B-3-25349 disclose Zn or Z.
A steel plate having a metal plating layer containing n as a main component and an organic resin film containing a metal powder as an upper layer is described.

However, in the organic resin film containing a metal powder described in the above three publications, 40 to 90% of the organic resin is occupied by a phenoxy resin. For this reason, when used as a gasoline tank, the properties of the outer surface side are such that the affinity of the hydroxyl group of the phenoxy resin with the metal powder is insufficient, and the metal powder may be detached from the film during press working. For this reason, peeling of the plating occurs on the outer surface side, and press formability deteriorates.

[0010] Further, on the inner surface side when used as a gasoline tank, the inner surface corrosion resistance of the portion damaged by the desorption of the metal powder and the peeling of the plating layer is deteriorated. Even in a flat part that has not been damaged, the corrosive liquid tends to stay between the resin and the metal powder in the film, and the inner surface corrosion resistance is poor.

Further, in any steel sheet, since the resin film on the inner and outer surfaces of the tank contains a hardening agent as an essential component, when the degree of hardening is high, it is difficult to thermally decompose, and it is difficult to remove the film during the nugget formation process. Seam weldability decreases.
That is, even if the energization point is secured by the inclusion of metal powder,
Since the base metal around the remaining film causes poor welding, sufficient wrap between nuggets cannot be obtained, and fuel leakage occurs.
In some cases, sufficient welding strength cannot be obtained and peeling occurs. In addition, when the curing degree is low and an unreacted curing agent is contained, the cohesive force of the part is low, corrosion factors (acids, chloride ions, etc.) easily enter, and the corrosion resistance of the inner and outer surfaces is reduced. As described above, the conventionally proposed materials have problems in various performances required as tank materials, and have not yet been put to practical use.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the disadvantages of previously used or proposed tank materials, and to mix alcohols, especially methanol itself, or a mixture of formic acid formed by the oxidation of methanol. It is an object of the present invention to provide a highly corrosion-resistant steel sheet which exhibits excellent internal corrosion resistance to gasoline and exhibits excellent press workability, seam weldability and external corrosion resistance in a tank manufacturing process.

[0013]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive studies and provided an organic resin film containing a metal powder having lubricity on one surface of a steel sheet,
By providing an organic film containing polyethylene wax and silica on the other surface, a new finding that these problems can be solved at once was obtained, and the present invention was completed.

That is, according to the present invention, A
a metal powder-containing organic resin film containing a metal powder and a Ni metal powder, an epoxidized diene-based block copolymer or an amine-modified epoxidized diene-based block copolymer, and a polyolefin wax; An object of the present invention is to provide a highly corrosion-resistant tank steel sheet having a silica-containing organic resin film containing a diene-based block copolymer, silica and a polyolefin wax as main components.

The present invention also provides a steel plate having on both surfaces Zn or Zn as a lowermost layer or a metal plating layer mainly composed of Fe as an upper layer, and a chromate film on the metal plating layers on both sides thereof. And a metal powder-containing organic resin film containing an Al metal powder and a Ni metal powder, an amine-modified epoxidized diene-based block copolymer, a polyolefin wax, and a curing agent on the upper layer of the chromate film on one surface. Has, on the upper layer of the chromate film on the other side,
An object of the present invention is to provide a steel plate for a highly corrosion-resistant tank having a silica-containing organic resin film mainly composed of an epoxidized diene-based block copolymer, silica and a polyolefin wax.

The present invention also provides a resin composition for coating a steel sheet.

The present invention also relates to a method for preparing a metal powder of 30 to 1 with respect to 100 parts by weight of an epoxidized diene-based block copolymer or an amine-modified epoxidized diene-based block copolymer.
It consists of 10 parts by weight and 5 to 20 parts by weight of a polyolefin wax, the content ratio of Ni metal powder / Al metal powder is 80/20 to 30/70 (weight ratio), and the Al metal powder has a major axis of 8 to 18 μm and a minor axis. 1-10 μm, thickness 1-5
An object of the present invention is to provide the above-mentioned metal powder-containing organic resin film having a scale shape of μm and a Ni metal powder having a particle size of 1 to 9 μm.

In the present invention, the amine-modified epoxidized diene-based block copolymer is used in an amount of from 0.2 to 1.0 equivalent per equivalent of epoxy group in the epoxidized diene-based block copolymer.
A composite resin obtained by adding 0 mol of an alkanolamine, wherein the polyolefin wax has a softening point of 70 to 1
An object of the present invention is to provide the metal powder-containing organic resin film having an average particle diameter of 1 to 7 μm at 50 ° C. and a metal powder-containing organic resin film having a thickness of 2 to 10 μm. Here, the amine-modified epoxidized diene-based block copolymer of the present invention may be a product cured with a curing agent.

Further, the present invention relates to 100 parts by weight of an epoxidized diene block copolymer, 5 to 80 parts by weight of silica, a softening point of 70 to 150 ° C. and an average particle size of 1 to 7 μm.
m and a glass transition temperature (T) of the silica-containing organic resin.
g) is 0 to 90 ° C., and the silica-containing organic resin film has a thickness of 0.5 to 1.5 μm.

Further, in the present invention, the metal plating layer containing Zn as a main component is formed of a Zn—Ni alloy plating, a Zn—Co alloy plating, a Zn—Fe alloy plating, a Zn—Ni—Cr alloy plating, a Zn—Ni alloy plating. -Co alloy plating or Zn-
An Al alloy, the basis weight of Zn or a metal plating layer mainly composed of Zn is 10 to 200 g / m 2, or the metal plating layer mainly composed of Fe is
The present invention provides a highly corrosion-resistant steel sheet for a tank, which is Zn plating or Fe-P plating and has a basis weight of an Fe-based plating layer of 3 to 8 g / m 2.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the steel sheet for a highly corrosion-resistant tank of the present invention (hereinafter referred to as “the steel sheet for a tank of the present invention”) will be described in detail.

(Metal Plating Layer) First, the steel sheet for a tank of the present invention has Zn or Zn as a lowermost layer on both surfaces of the steel sheet or a metal plating layer containing Fe as a main component on the lower layer. Since the metal plating layer is a metal layer having a lower potential than an iron base in alcohol and an alcohol-mixed fuel, Z is applied even in a pressed portion where the plating layer is damaged.
By the sacrificial anticorrosive action of n or Fe, the occurrence of red rust and perforation can be suppressed, and the outer corrosion resistance of the tank can be improved. On the other hand, the inner surface can prevent permeation of the formic acid aqueous solution by the barrier effect of the organic film, and can suppress the elution of Zn, which is weak against acid, and the formation of a floating white precipitate due to this.

Further, when the metal plating layer is an alloy plating layer containing Zn as a main component, the elution rate of the plating layer during the sacrificial anticorrosion action is slowed down, so that the weight per unit area is lower than that in the case of a Zn-only plating layer. The amount can extend the perforated life of the tank. Further, the corrosion resistance when combined with an upper chromate layer or an organic resin film containing a metal powder described later is further improved. In the present invention, Zn-Ni alloy plating, Zn-C
o alloy plating, Zn-Fe alloy plating, Zn-Al alloy plating, Zn-Ni-Cr alloy plating, Zn-Ni-C
Any of the o-alloy plating is suitable.

In the steel sheet for tanks of the present invention, the coating weight of Zn or a metal plating layer containing Zn as a main component is as follows:
It is preferably from 10 to 200 g / m2, more preferably from 2 to 200 g / m2.
0 to 100 g / m2. 10 g / m plating weight
If it is less than 2, the effect of hiding the steel sheet surface becomes insufficient, and the corrosion resistance required for the lower layer is insufficient. If it exceeds 200 g / m 2, the corrosion resistance of the lower layer is saturated.

In the present invention, the method of forming Zn or the metal plating layer containing Zn as a main component is not particularly limited, and it can be formed by a known electroplating method or hot-dip plating method. For example, the Zn plating layer is ZnSO4.
Using a mixed solution of 410 g / l 7H2 O, 20 g / l AlCl3 and 75 g / l Na2 SO4,
-5, temperature 20-30 ° C, current density 1-10A / dm2
Can be formed by a method of electroplating.
The metal plating layer containing Zn as a main component is made of Zn-Ni
In the case of alloy plating, ZnSO4.7H2O 300g /
and a mixed solution of 200 g / l of NiSO2.6H2 O, and in the case of Zn--Co alloy plating, ZnSO
4.7H2O 200g / l, CoSO4.7H2O
A mixed solution of 200 g / l and 45 g / l of Na2 SO4 was used. In the case of Zn-Fe alloy plating, ZnSO
4.7H2O 110g / l, FeSO4.7H2O
100 g / l, (NH4) 2 SO4 20 g / l, KC
120 g / l, and 60 g of second antimony citrate /
In the case of Zn-Ni-Cr alloy plating, a mixed solution of ZnSO4.7H2O 160 g / l, NiSO
4.6H2O 240g / l and CrO 32g /
In the case of Zn-Ni-Co alloy plating, 100 g / l of ZnSO4.7H2O, NiSO
4.6H2O 60 g / l, CoSO4.7H2O60
g / l, (NH4) 2 SO4 5 g / 1, and H2 SO4
It can be formed using a mixed solution of 10 g / l. At this time, the plating baths each had a pH of 2.0 to 4.0.
5, and can be performed under the conditions of a current density of 5 to 50 A / dm 2 and a room temperature to 60 ° C. Further, Zn-A
In the case of 1 alloy plating, Al 4-5 wt%, Zn 9
Hot-dip bath consisting of 5-96 wt% or Al
It can be formed by a hot-dip plating bath composed of 50 to 60 wt% and 50 to 40 wt% of Zn.

The steel sheet for a tank of the present invention may have an Fe-based plating layer on the metal plating layer on both sides of the steel sheet. This Fe-based plating layer has a different reactivity between the chromate film provided on the upper layer and the plating surface due to the oxide film of Al or the like present on the surface of the metal plating layer containing Zn or Zn as a main component, and the chromate film becomes uneven. To prevent the adhesion of the organic resin film to deteriorate and the corrosion resistance of the inner and outer surfaces to decrease, and to make the chromate film adhere evenly.
It is provided to improve the adhesion of the organic resin film.

In the present invention, the Fe-based plating layer is also effective in preventing so-called flaking or powdering in which the plating layer is pulverized when the plating layer is peeled off during press working. Furthermore, since Fe has a higher specific resistance than zinc, it also contributes to improvement in spot welding and seam weldability. Therefore, the steel sheet for a tank of the present invention in which the Fe-based plating layer is provided on the metal plating layer containing Zn or Zn as a main component, compared with the case where Zn or Zn is used alone as a press-forming material, It is effective in improving resistance weldability and corrosion resistance of the inner and outer surfaces.

As the Fe-based plating layer, for example, F
Examples include those made of e-Zn plating, Fe-P plating, and the like. Among these, Fe-Zn plating or Fe-Zn plating
What consists of -P plating is preferable. The coating weight of the Fe-based plating layer is preferably 3 to 8 g / m2. If it is less than 3 g / m 2, the hiding effect of the underlying Zn or the metal plating layer containing Zn as a main component is insufficient. 8
If it exceeds g / m2, the amount of red rust generated increases and the corrosion resistance deteriorates. The Fe-based plating layer is not particularly limited, and can be formed according to a known electroplating method or hot-dip plating method.

(Chromate Layer) Next, the steel sheet for a tank of the present invention has a chromate film on the metal plating layers on both surfaces. The amount of chromium deposited on the chromate film is 5 to 200 mg / m 2, more preferably 10 to 100 mg / m 2, in terms of chromium metal. When the amount of adhesion is less than 5 mg / m 2, the adhesiveness with the organic film on the upper layer is insufficient, so that the film on the sliding portion is peeled off during press working, and in some cases, even the plating layer is peeled off. In addition, since the amount of adhesion is small, the hexavalent chromium component to be used for self-repair may be insufficient, and in addition to the peeling of the plating layer, the corrosion resistance of the processed portion on the inner and outer surfaces may be insufficient. If the adhesion amount exceeds 200 mg / m2, the chromate film itself becomes very brittle, and the chromate film is peeled off at the sliding work portion, and the accompanying organic resin film or layer is also peeled off. The corrosion resistance of the processed part may be insufficient.

The formation of the chromate film can be performed according to a usual processing method, and is not particularly limited.
For example, immersion chromate treatment, electrolytic chromate treatment, or the like may be performed in an aqueous solution mainly containing chromic anhydride, chromate, dichromic acid, or the like, or a treatment solution in which colloidal silica or the like is mixed with the aqueous solution may be applied to a plated steel sheet. A coating mainly composed of chromium hydrate may be formed by performing a coating-type chromate treatment for coating on the surface. After the plated steel sheet is treated with the 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 or a drying step such as hot air drying.

The steel sheet for a tank according to the present invention comprises metal powder, a terminal amine-modified epoxidized diene-based block copolymer, a curing agent and a polyolefin wax as main components on the upper layer of the chromate film and as the uppermost layer. Having a metal powder-containing organic resin film containing a metal powder having lubricity, containing a curing agent as required, and having a silica-containing organic resin film containing resin, silica and polyolefin wax on the outer surface side Things. Since the inner surface of the steel plate for a tank of the present invention is excellent in weldability, gasoline resistance, lubricity and the like, it is preferably used as the inner surface of the gasoline tank (that is, the side in contact with gasoline). The outer surface is preferably used as the outer surface of a gasoline tank because of its excellent corrosion resistance and lubricity.

(Metal Powder-Containing Organic Resin Film) The metal powder-containing organic resin film provided on the uppermost layer on the inner surface side of the steel plate for a tank of the present invention contains alcohol, particularly methanol itself, or formic acid generated by oxidization of methanol. Consists of a resin composition containing a metal powder having excellent corrosion resistance and durability to gasoline, and plays a role of an anticorrosion layer for preventing direct contact between the lower metal plating layer and the chromate layer and the alcohol fuel. Layer.

(Metal Powder) In the steel sheet for a tank of the present invention, the metal powder to be added to the metal-powder-containing organic resin film is added to ensure resistance weldability. That is, since the organic resin film generally has high electric insulation and the thickness of the resin film is 2 to 10 μm, no exposure of the convex portion of the steel sheet can be expected at all, and resistance welding is difficult. . Accordingly, the present invention is to disperse a required amount of metal powder in an organic resin film on the inner surface side of a gasoline tank to enhance the conductivity of the film.

As for the metal powder used, the one having a higher specific resistance has a larger calorific value and is more useful.
Metal powders such as Al, Fe, and Cu can be used. Among these, Ni is most useful because it has excellent corrosion resistance and high specific resistance to methanol. Further, Al has a lower specific resistance and melting point than Ni, and is not necessarily optimal for welding. However, a flaky shape is useful for suppressing permeation of a formic acid aqueous solution in an organic film. Therefore, in the present invention, Al metal powder and Ni metal powder are combined,
It is effective to add an appropriate ratio to the organic resin film.

The shape of the metal powder may be any of a granular shape and a flake shape, but is appropriately selected so as to obtain a required inner surface corrosion resistance or resistance weldability. (As described above, the inner surface corrosion resistance and the resistance weldability slightly change depending on the shape.) For example, the Ni powder is preferably a granular one having a particle size of 1 to 9 µm, more preferably 2 to 7 µm. Particle size 1μm
If the particle size is less than 9 μm, the current-carrying point is insufficient, and if the particle size exceeds 9 μm, the current-carrying point is sufficiently provided, so that the addition of a small amount improves the resistance weldability. On the other hand, since the coating is porous, the corrosion resistance on the inner surface is deteriorated, and powdering of the coating at the time of press working is also a problem. Al metal powder has a major axis of 8 ~
18 μm, 1 to 10 μm in minor axis, 1 to 5 μm in thickness of scaly, more preferably the major axis of Al powder is 10 to 10 μm
The thickness is 15 μm, the minor axis is 5 to 8 μm, and the thickness is 2 to 4 μm. When the major axis and the minor axis of the Al metal powder are less than 8 μm and less than 1 μm, respectively, the area of the flakes becomes small, so that the ability to suppress the permeation of an aqueous solution such as formic acid is reduced, and the inner surface corrosion resistance is reduced. The same applies to the case where only the major axis or the minor axis alone is short. On the other hand, when the major axis and the minor axis exceed 18 μm and 10 μm, respectively, the organic resin film becomes too porous, resulting in insufficient strength of the film and brittleness.
For this reason, there is a possibility that powdering may occur or the inner surface corrosion resistance of the pressed portion may be reduced. The thickness is 1μm
If less, the life of the inner surface corrosion resistance is shortened. On the other hand, when the thickness exceeds 5 μm, the ratio of the Al powder exposed on the surface of the coating film becomes too large, so that the resistance weldability decreases.

The amount of the metal powder in the metal powder-containing organic resin film is 30 to 110 parts by weight, preferably 45 to 100 parts by weight, per 100 parts by weight of the amine-modified epoxidized diene block copolymer. Amount. If the amount is less than 30 parts by weight, the current-carrying point is insufficient and the conductivity is poor, so that the resistance weldability may be reduced. If the amount exceeds 90 parts by weight, the organic resin film itself becomes brittle, so that the powdering resistance at the time of pressing is reduced and the internal corrosion resistance may be reduced.

In addition, Ni in the metal powder-containing organic resin film
Content ratio of metal powder / Al metal powder is 80/20 to 30
/ 70 (weight ratio), more preferably 70 /
30 to 40/60. If the content ratio of Ni metal powder / Al metal powder is less than 30/70, the amount of Ni having a high specific resistance is insufficient, and the resistance weldability may be reduced. On the other hand, when the ratio exceeds 80/20, the amount of Al having a function of suppressing the penetration of alcohol-based fuel is insufficient, so that the internal corrosion resistance may be reduced.

(Epoxidized diene block copolymer)
The epoxidized diene-based block copolymer blended in the film of the present invention has excellent corrosion resistance and durability against fuel containing gasoline, alcohol, or formic acid, and has a base plate (steel plate + metal plating layer + It exhibits excellent properties in terms of coating film adhesion to the chromate layer) and press moldability. Further, the amine-modified epoxidized diene-based block copolymer is obtained by adding an amine to an epoxy group of an epoxidized diene-based block copolymer forming a main skeleton.

The epoxidized diene-based block copolymer is
It is obtained by epoxidizing a block copolymer composed of a polymer block mainly composed of a vinyl aromatic compound and a polymer block mainly composed of a conjugated diene compound. Here, in a block copolymer composed of a polymer block mainly composed of a vinyl aromatic compound and a polymer block mainly composed of a conjugated diene compound, the weight ratio of the vinyl aromatic compound to the conjugated diene compound (the block copolymer Is 5/95 to 80/20, especially 10/95.
A weight ratio of 90-60 / 40 is preferred. The number average molecular weight of the block copolymer used in the present invention is from 5,000 to
1,000,000, preferably 10,000-80
000, and the molecular weight distribution [ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / M
n)] is 10 or less. The molecular structure of the block copolymer may be linear, branched, radial, or any combination thereof.

For example, XYX, YXYX,
It is a vinyl aromatic compound (X) block-conjugated diene compound (Y) block copolymer having a structure such as (XY-) 4Si or XYXYX. Further, the unsaturated bond of the conjugated diene compound of the diene-based block copolymer may be partially hydrogenated.

Examples of the vinyl aromatic compound constituting the diene block copolymer include styrene, α-methylstyrene, vinyltoluene, p-tertiary butylstyrene, divinylbenzene, p-methylstyrene, 1,1-
One or more of diphenylstyrene and the like can be selected, and among them, styrene is preferable. As the conjugated diene compound, for example, butadiene, isoprene,
1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, piperylene, 3-butyl-1,3-octadiene, phenyl-1,3-butadiene, etc.
A species or two or more species are selected, and among them, butadiene, isoprene and a combination thereof are preferred.

As a method for producing the block copolymer used in the present invention, any production method having the above-mentioned structure can be adopted. For example,
23798, JP-B-47-3252, JP-B-48-
No. 2423, JP-A-51-33184, JP-B-46-
No. 32415, JP-A-59-166518, Japanese Patent Publication No. Sho 4
Nos. 9-36957, JP-B-43-17979, JP-B-46-32415, JP-B-56-28925, and the like. A compound-conjugated diene compound block copolymer can be synthesized. Further, hydrogenation in an inert solvent in the presence of a hydrogenation catalyst by a method described in JP-B-42-8704, JP-B-43-6636, or JP-A-59-133203, The partially hydrogenated block copolymer used in the present invention can be synthesized.

The epoxidized diene block copolymer in the present invention can be obtained by reacting the above block copolymer with an epoxidizing agent such as hydroperoxides and peracids in an inert solvent. Examples of peracids include formic acid, peracetic acid, and perbenzoic acid. In the case of hydroperoxides, a catalytic effect can be obtained by using a mixture of tungstic acid and caustic soda with hydrogen peroxide, an organic acid with hydrogen peroxide, or molybdenum hexacarbonyl with tertiary butyl hydroperoxide. .

There is no strict limit on the amount of epoxidizing agent,
The optimal amount in each case will depend on variables such as the particular epoxidizing agent used, the degree of epoxidation desired, the particular block copolymer used, and the like.

The obtained epoxidized diene copolymer is isolated by an appropriate method, for example, a method of precipitating with a poor solvent, a method of pouring the polymer into hot water with stirring and distilling off the solvent, or a method of directly removing the solvent. It can be performed by a desolvation method or the like.

The epoxy equivalent of the obtained epoxidized (hydrogenated) diene block copolymer is preferably from 300 to 1
It is in the range of 0000.

In the amine-modified epoxidized diene-based block copolymer, the amine to be added to the epoxy group of the epoxy resin includes monoalkanolamines such as ethylethanolamine and ethanolamine, diethanolamine, dipropanolamine and dibutanolamine. Alkanolamines such as dialkanolamines are mentioned. To further increase the low-temperature reactivity with the curing agent described below,
Dialkanolamine which can introduce more primary hydroxyl groups is preferable. In the amine-modified epoxidized diene-based block copolymer, the number of moles of the alkanolamine added to one equivalent of the epoxy group of the epoxidized diene-based block copolymer as the main skeleton is from 0.1 to 1.0 mol. When the number of moles of the added alkanolamine is less than 0.1, the degree of amine modification is insufficient, so that the affinity between the metal powder and the amine-modified epoxidized diene-based block copolymer is reduced, and the metal powder during press working is reduced. May be detached from the film.

When the degree is severe, the plating layer is peeled off, and the press formability may be deteriorated. For the same reason, the corrosive liquid tends to stay between the resin and the metal powder in the film, and sufficient hydrophobicity cannot be obtained, and formic acid aqueous solution is easily introduced into the film. The internal corrosion resistance to methanol-based fuel having high strength may be insufficient.

(Polyolefin Wax) In the steel sheet for a tank of the present invention, a polyolefin wax is blended in order to impart lubricity to the metal powder-containing organic resin film formed on the inner surface. Generally, in order to obtain a film having a high degree of lubricity that can be continuously formed, the film does not peel off even under severe press forming conditions accompanied by heat generation of sliding parts such as high-speed press forming. It is desirable to use a base resin component having a glass transition temperature. here,
When using a lubricant with a low coefficient of friction and protruding from the resin film surface, the lubricant absorbs the frictional impact with the mold during press working, and is comparable to the case of using a base resin component having a low glass transition temperature. This is effective because lubricity can be obtained. That is, by using a lubricant projecting to the surface of the resin film, even if a base resin having a glass transition temperature as low as about 40 ° C. is used, required lubricity can be obtained, which is effective. In the steel sheet with this metal powder-containing organic resin film, the lubricant projected onto the resin film surface during press molding reduces friction with the mold, prevents damage to the resin film, and improves continuous productivity during industrial production. Can be achieved.

The polyolefin wax preferably has an average particle size of 1 to 7 μm, more preferably 2 to 6 μm. When the average particle size is less than 1 μm, the amount of the lubricant projecting from the metal powder-containing organic resin film is small, and sufficient press workability cannot be obtained. On the other hand, when the average particle size exceeds 7 μm, the metal powder-containing organic resin film becomes too brittle and the powdering resistance of the film is reduced, so that the press formability is poor.

This polyolefin wax has a melting point of 7
Any material may be used as long as it is in the range of 0 to 150 ° C. Preferred are polymers of olefinic hydrocarbons such as polyethylene, polypropylene and polybutene. Further, a combination of a material having a low melting point and a material having a high melting point may be used in combination, whereby better press workability can be obtained. When a polyolefin wax having a melting point of less than 70 ° C. is used, under severe pressing conditions involving heat generation, the elasticity of the wax layer is significantly reduced, so that lubricity is reduced and press formability is poor. When a polyolefin wax having a melting point of more than 150 ° C. is used, the softening of the wax is insufficient and the wax layer is too strong, so that the lubricity is reduced and the press formability is poor.

In the metal powder-containing organic resin film, the amount of the polyolefin wax is preferably 5 to 20 parts by weight, more preferably 10 to 15 parts by weight, based on 100 parts by weight of the amine-modified epoxy resin. It is the amount which becomes the ratio of. If the amount is less than 5 parts by weight, the amount of wax particles protruding from the surface of the metal powder-containing organic resin film is insufficient, and the lubricity is insufficient. If it exceeds 20 parts by weight, the brittle polyolefin wax component becomes unnecessarily large, and the film strength and lubricity are reduced.

(Curing Agent) The metal powder-containing organic resin film of the present invention can also contain a curing agent. By adding a curing agent, the inner surface corrosion resistance can be further improved. Examples of the curing agent used include, for example, isocyanate-based curing agents, amine-based curing agents, melamine-based curing agents, dicyandiamide-based curing agents, hydrazide-based curing agents, phenol-based curing agents, boron-based curing agents, and imidazole-based curing agents. Can be mentioned. Such a curing agent is blended so as to react with the resin component.

The mixing ratio of the curing agent in the metal powder-containing organic resin film is from 2 to 20 parts by weight based on 100 parts by weight of the epoxidized diene-based block copolymer or the amine-modified epoxidized diene-based block copolymer (solid content). Parts by weight, preferably 4 to 10 parts by weight. If the compounding ratio of the curing agent is less than 2 parts by weight, the degree of curing is too low, so that the ability to suppress formic acid permeation is insufficient and the internal corrosion resistance is reduced. In addition, since the toughness of the film is insufficient, press formability is reduced. on the other hand,
If the amount exceeds 20 parts by weight, the unreacted curing agent makes the resin film brittle, so that the press formability decreases. Further, the unreacted curing agent induces a corrosion factor (acid, chloride ion, etc.), and the internal corrosion resistance is reduced.

It is necessary to consider the thickness of the metal powder-containing organic resin film depending on the place where the steel sheet for a tank of the present invention is used. The inner surface preferably has a thickness of 2 to 10 μm, and if the thickness is less than 2 μm, the inner surface required for the outer layer has insufficient corrosion resistance. If it exceeds 10 μm, the corrosion resistance is saturated, and the press workability and the seam weldability are reduced.

If necessary, additives such as a lubricant, a coupling agent, a pigment, a thixotropic agent, and a dispersant may be added to the metal powder-containing organic resin film.

In the present invention, the metal powder-containing organic resin film is formed, for example, by adding an alkanol to an epoxidized diene-based block copolymer having an epoxy equivalent of 300 to 10,000. It is obtained by adding an amine and reacting at room temperature to 100 ° C. for 4 to 5 hours. Next, with a sand mill or an attritor, the metal powder, polyolefin wax and a curing agent, and additives that are added as necessary, are added and dispersed in the amine-modified epoxidized diene-based block copolymer, and a predetermined ratio is added. An organic resin paint containing a metal powder is prepared and applied on a chromate film to form a film.

(Silica-Containing Organic Resin Film) In the steel sheet for a tank of the present invention, the silica-containing organic resin film formed on the outer surface side contains an epoxidized diene-based block copolymer, silica, and a polyolefin wax.
This is effective because the epoxidized diene-based block copolymer reacts with hydroxyl groups on the surface of the silica particles to form an inorganic-organic composite film having high corrosion resistance and can improve the corrosion resistance of the outer surface of the tank.

(Silica) Silica is blended in order to impart corrosion resistance to the silica-containing organic resin film on the outer surface side. As the silica used, colloidal silica (for example,
Snowtex-O, Snowtex-N manufactured by Nissan Chemical Co., Ltd., organosilica sol (for example, Nissan Chemical Co., Ltd.)
Ethyl cellosolve silica sol), silica powder (for example, gas-phase silica powder made by Aerosil Co., Ltd.), and organic silicate which becomes silica by self-condensation (for example, ethyl silicate or the like is used in combination with an acid catalyst).
The particle size of the silica is preferably in the range of 5 to 70 nm from the viewpoint that the silica can be uniformly dispersed.

The amount of silica and polyolefin wax in the silica-containing organic resin film is 5 to 8 parts by weight based on 100 parts by weight of the base resin.
0 parts by weight, preferably 20 parts by weight.
６０60 parts by weight. If the amount is less than 5 parts by weight, the corrosion resistance is reduced. If the amount is more than 80 parts by weight, the silica-containing organic resin film becomes brittle, and the mold is seized at the time of molding to deteriorate the pressability. In addition, since silica has poor thermal decomposability, resistance weldability decreases.

A silane coupling agent may be used as a reaction accelerator between the epoxidized diene-based block copolymer and silica. Examples of the silane coupling agent used include γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and the like. Further, general additives such as a reaction accelerator, a stabilizer and a dispersant may be appropriately added to the base resin within a range that does not impair the gist of the present invention.

(Polyolefin Wax) In the present invention, a polyolefin wax is added to impart lubricity to the silica-containing organic resin film. The polyolefin wax preferably has an average particle size of 1 to 7 μm, more preferably 2 to 6 μm. When the average particle size is less than 1 μm, the amount of the polyolefin wax projecting from the organic film is small, and the press workability is reduced.
If it exceeds 7 μm, the silica-containing organic resin film becomes too brittle and the powdering resistance of the film is reduced, so that the press formability may be reduced.

This polyolefin wax has a melting point of 7
Any material may be used as long as it is in the range of 0 to 150 ° C. Preferred are polymers of olefinic hydrocarbons such as polyethylene, polypropylene and polybutene. Further, a combination of a low melting point and a high melting point may be used, and depending on the combination, better press workability can be obtained. When a polyolefin wax having a melting point of less than 70 ° C. is used, under severe pressing conditions involving heat generation, the elasticity of the wax layer is significantly reduced, so that lubricity is reduced and press formability is poor. When a polyolefin wax having a melting point of more than 150 ° C. is used, the softening of the wax is insufficient and the wax layer is too strong, so that the lubricity is reduced and the press formability is poor.

The compounding amount of the polyolefin wax is preferably 1 to 40 parts by weight, more preferably 5 to 40 parts by weight, based on 100 parts by weight of the epoxidized diene-based block copolymer.
30 parts by weight. If the amount exceeds 40 parts by weight, the strength of the resin layer decreases, and the lubricity decreases. On the other hand, if it is less than 1 part by weight, lubricity is insufficient.

The silica-containing organic resin constituting the silica-containing organic resin film obtained by blending the above-mentioned base resin, silica and polyolefin wax, and additives added as required, has a glass transition temperature (Tg). 0 to
90 ° C. When the glass transition temperature is out of this range, the press workability of the obtained steel sheet for a tank is poor, and the corrosion resistance of the pressed portion is also poor.

In the steel sheet for a tank of the present invention, the thickness of the silica-containing organic resin film is 0.5 μm in dry film thickness on one side.
It is preferably 1.5 μm. 0.5 μm thick
If it is less than 3, the unevenness of the steel sheet surface cannot be filled, and the corrosion resistance is reduced. If it exceeds 1.5 μm, the corrosion resistance is improved, but the resistance weldability is significantly reduced. Further, the wettability of the metal brazing is remarkably poor, and the brazing property is also remarkably reduced.

In the steel sheet for a tank of the present invention, the metal powder-containing organic resin film on the inner surface is mainly composed of the above-mentioned amine-modified epoxidized diene-based block copolymer, and an appropriate amount of an organic solvent or a curing agent, metal powder. Furthermore, it can be formed by coating and drying as a coating composition containing other commonly used additive components.

This resin mixture or composite is applied on the outer layer of the chromate film by roll coating, spray coating,
Coating is performed so as to have a predetermined thickness by a known general method such as dip coating, and is usually performed at 50 to 180 ° C., usually 3 to 9
It can be performed by drying for 0 seconds.

In the steel sheet for a tank of the present invention, a lubricating oil may be applied to the inner surface and the outer surface according to the degree of difficulty of the press working at the time of press forming, and it is rather effective from the viewpoint of preventing damage to the film. .

[0070]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

(Examples 1 to 12, Comparative Examples 1 to 7) A steel plate for a high corrosion resistant tank of the present invention and various comparative materials were obtained by using a cold rolled steel plate (SPCC) having a thickness of 0.8 mm as an original plate. In manufacturing, after performing pretreatment (electrolytic degreasing, electrolytic pickling), galvannealed steel sheet (Fe10 wt.
%).

On the above-mentioned plated steel sheet, 40 mg /
An m2 chromate film and a resin film were formed by roll coating, drying and baking to obtain a steel plate for a tank. The amount of alkanolamine added in the examples is 0.5 with respect to 1 equivalent of epoxy group in the epoxidized diene block copolymer. The epoxidized diene block copolymer used in the examples was prepared as follows.

Preparation Example 1 300 g of a block copolymer of polystyrene-polybutadiene-polystyrene [styrene / butadiene weight ratio = 40/60] was placed in a jacketed reactor equipped with a stirrer, a reflux condenser, and a thermometer, and ethyl acetate. 1500 g was charged and dissolved. Then 3 of peracetic acid
165 g of a 0 wt% ethyl acetate solution was continuously dropped, and an epoxidation reaction was performed at 40 ° C. for 3 hours with stirring. The reaction solution was returned to room temperature and taken out of the reactor, and a large amount of methanol was removed.
Then, a polymer was precipitated by filtration, filtered, washed with water and dried to obtain an epoxy-modified polymer. The obtained epoxidized diene-based block copolymer is referred to as a copolymer A (epoxy equivalent of the copolymer is 490).

Preparation Example 2 300 g of a block copolymer of polystyrene-polybutadiene-polystyrene [styrene / butadiene weight ratio = 20/80] 300 g and cyclohexane 3000 g were placed in a jacketed reactor equipped with a stirrer, a reflux condenser, and a thermometer. The mixture was dissolved at a temperature of 60 ° C., and 40 ml of a di-P-tolylbis (1-cyclopentadienyl) titanium / cyclohexane solution (concentration: 1 mmol / l) as a hydrogenation catalyst and an n-butyllithium solution (concentration: 5 mmol) / Liter) at 0 ° C. under a hydrogen pressure of 2.0 kg / cm 2, and reacted at a hydrogen partial pressure of 2.5 kg / cm 2 for 60 minutes. The solvent was removed from the obtained partially hydrogenated polymer solution by drying under reduced pressure (the hydrogenation rate of the entire butadiene portion was 80%).
%). 300 g of this partially hydrogenated polymer, 1 part of cyclohexane
500 g was charged and dissolved. Then 30% by weight of peracetic acid
200 g of ethyl acetate solution was continuously dropped, and the mixture was stirred at 40 ° C.
For 3 hours. The reaction solution was returned to room temperature, taken out of the reactor, and a large amount of methanol was added to precipitate a polymer. The polymer was separated by filtration, washed with water, and dried to obtain an epoxy-modified polymer. The obtained epoxidized diene-based block copolymer is referred to as a copolymer B (an epoxy equivalent of the copolymer is 460).

Preparation Example 3 300 g of a block copolymer of polystyrene-polyisoprene-polystyrene [styrene / isoprene weight ratio = 30/70] was placed in a jacketed reactor equipped with a stirrer, reflux condenser, and thermometer, and cyclohexane. 2500 g were charged and dissolved, a nickel catalyst was added as a hydrogenation catalyst, and the mixture was reacted at a hydrogen partial pressure of 15 kg / cm 2 and a temperature of 150 ° C. for 3 hours. The solvent was removed from the obtained partially hydrogenated polymer solution by drying under reduced pressure (the degree of hydrogenation of the entire isoprene part was 85%). This partially hydrogenated polymer 300
g of cyclohexane and 1500 g of cyclohexane. Subsequently, 150 g of a 30% by weight solution of peracetic acid in ethyl acetate was continuously dropped, and an epoxidation reaction was carried out at 40 ° C. for 3 hours with stirring. The reaction solution was returned to room temperature, taken out of the reactor, and a large amount of methanol was added to precipitate a polymer. The polymer was separated by filtration, washed with water, and dried to obtain an epoxy-modified polymer. The obtained epoxidized diene-based block copolymer is referred to as a copolymer C (epoxy equivalent of the copolymer is 750).

The composition of the rubber-modified epoxy resin used in the comparative example is as follows. Rubber-modified epoxy resin a: Novolak type epoxy resin 7
Butadiene / acrylonitrile copolymer rubber 2 in 5 parts by weight
A blend of 5 parts by weight. Rubber-modified epoxy resin b: novolak type epoxy resin 8
Butadiene / acrylonitrile copolymer rubber 1 in 5 parts by weight
A blend of 5 parts by weight.

With respect to the steel sheets for tanks obtained in Examples and Comparative Examples, press workability, resistance weldability, external shochu, internal corrosion resistance, and brazing properties were evaluated according to the evaluation methods described below. . The results are shown in Tables 1 and 2.

(A) Evaluation of press formability Evaluation of powdering resistance of the coating by a cylindrical molding test: 1 g / m 2 of rust preventive oil Z5 manufactured by Idemitsu Oil Co., Ltd. was applied and evaluated under the following press conditions. Was. Punch diameter and shape ・ ・ ・ 33mmφ Flat bottom cylindrical clearance ・ ・ ・ 1mm Blank size ・ ・ ・ 66mm Wrinkle holding load ・ ・ ・ 2t Drawing speed ・ ・ ・ 60mm / sec Under the above press conditions, cylindrical steel sheet, steel sheet after forming The degree of powdering of the coating on the outer surface was evaluated by visual observation. The evaluation criterion was evaluated as レ ベ ル when the powdering of the film was not visually observed, and as X when the powdering amount was large.

(B) Evaluation of resistance weldability Seam welding conditions: Electrode: chrome-copper alloy, trapezoidal electrode (tip R: 15 m
mφ) Welding method: Double upset, lap seam welding Pressure: 400 kg Energizing time: 2 cycles on, 1 cycle off Cooling: Internal and external water cooling Welding speed: 2.5 m / min Welding current: Various changes Under the above welding conditions, two steel plates were welded to each other to prepare a test piece. The test piece was subjected to a T-peel tensile test to check for breakage of the base material, and a range of an appropriate welding current (kA) was determined from the degree of nugget wrap to evaluate seam weldability.

(C) Method for evaluating outer surface corrosion resistance A steel sheet was coated with a topcoat paint (Emaron, manufactured by Dainippon Paint Co., Ltd.).
Was applied to a dry film thickness of 10 μm and baked in a furnace at 120 ° C. for 20 minutes. Thereafter, JASO (salt spray 2 hours → 60 ° C., 20-30 RH% drying 4 hours → 50)
(C, 98 RH% for 2 hours), the flat portion was subjected to a CCT test of 300 cycles, and the others were subjected to a CCT test of 100 cycles, and the residual plate thickness (mm) of the flat portion and the cross cut of the flat portion was measured. ) The residual plate thickness (mm) of the side wall of the molded product press-molded under the condition (2) was measured and used as an index for evaluation. The plate thickness before the test was 1.0 mm.

(D) Method of Evaluating Inner Surface Corrosion Resistance The corrosion resistance was evaluated for the flat surface and the inner surface of the flat-bottomed cylindrical cup formed under the conditions of (A) (2). The evaluation of the corrosion resistance of the flat part was performed by using unleaded gasoline / 500 ppm formic acid aqueous solution as 1 /
In fuel prepared by mixing at a ratio of 1 (weight), 20 m
A test piece of mx 100 mm is immersed for a length of 80 mm,
After performing a one-month immersion test at room temperature, the degree of rusting was evaluated in terms of area ratio (%). For the evaluation of the corrosion resistance of the inner surface of the flat-bottomed cylindrical cup, a test piece of a cylindrical cup having a bottom radius of 33 mmφ and a height of 30 mm was formed. Next, the above-mentioned fuel was charged up to 80% of the internal volume of the test specimen, and immersed for one month at room temperature.
The degree of rusting on the inner surface of the cup was determined by the total area ratio (%) of red rust and white rust. When the fuel was allowed to stand, a formic acid aqueous solution was separated in the lower layer and an unleaded gasoline in the upper layer from the permutation of specific gravity. Therefore, the red rust and white rust generation area ratio at each site was evaluated.

(E) Brazing properties Two test pieces having a size of 15 mm × 200 mm were prepared, and steel plates were overlapped with each other at a size of 15 mm × 15 mm, and brazing was performed between them (IS-344 manufactured by Ishifuku Metal Industry Co., Ltd. (JIS)). Standard name: King Solder # 101) and flux (Ishifuku Flux # 6 manufactured by Ishifuku Metal Industries Co., Ltd.) were used, and the heating time was fixed at 10 seconds to perform gas heating and brazing. Thereafter, a shear tensile test was performed, and the case where the base material was broken was evaluated as ○, the case where the base material was separated between the base material and the wax was evaluated as x, and the middle between the two was evaluated as Δ.

[0083]

[Table 1]

[0084]

[Table 2]

[0085]

The steel sheet for a high corrosion resistant tank according to the present invention has excellent corrosion resistance, press workability, resistance weldability, and brazing properties, and is particularly useful as a steel sheet for alcohol and alcohol-mixed gasoline tanks.

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C08K 3/36 C08L 23/00 C08L 23/00 C09D 5/10 C09D 5/10 153/00 153/00 163/00 163 / 00 C23C 28/00 C C23C 28/00 B60K 15/02 ZF term (reference) 3D038 CA04 CA06 CB01 4F100 AA20A AA20H AA22E AB01D AB02D AB03B AB10A AB10C AB10H AB16A AB16C AB16H AB18D AK03C AK11A28A AK03A AK11A AL05A AL05C AL06A AL06C BA02 BA03 BA05 BA10A BA10C BA13 CA23A CA23C DA01 DE01A DE01C DE01H EH71D EJ69E GB16 GB32 JB02 JB20A JB20C JL01 YY00A YY00C YY00H 4J002 BB002 CD18 DA076 FA0FA0 012 076 DA086 FA09 016 NA03 NA23 PB04 PB07 PC02 4K044 AA02 AB02 BA06 BA10 BA14 BA15 BA21 BB03 BB04 BB05 BB09 BB11 BC02 BC05 BC08 CA11 CA16 CA53 CA62

Claims (14)

[Claims] 1. An epoxidized diene-based block copolymer or an amine-modified epoxidized diene-based block copolymer,
A resin composition comprising a polyolefin wax, Al metal powder and Ni metal powder. 2. An epoxidized diene-based block copolymer or an amine-modified epoxidized diene-based block copolymer 1.
100 parts by weight, consisting of 30 to 110 parts by weight of metal powder and 5 to 20 parts by weight of polyolefin wax.
i metal powder / Al metal powder content ratio is 80 / 20-3
The resin composition according to claim 1, wherein the ratio is 0/70 (weight ratio). 3. An amine-modified epoxidized diene block copolymer obtained by adding 0.2 to 1.0 mol of alkanolamine to 1 equivalent of epoxy group in the epoxidized diene block copolymer. The resin composition according to claim 1, wherein the resin composition is a resin composition. 4. An epoxidized diene-based block copolymer,
A resin composition comprising silica and a polyolefin wax. 5. An epoxidized diene block copolymer 1.
The resin composition according to claim 4, comprising 5 to 80 parts by weight of silica and 1 to 40 parts by weight of a polyolefin wax based on 00 parts by weight. 6. An epoxidized diene-based block copolymer comprising a polymer block mainly composed of vinyl aromatic in the same molecule and a polymer block mainly composed of a conjugated diene compound partially containing epoxy. The resin composition according to any one of claims 1 to 5, comprising a polymer block mainly composed of a hydrogenated conjugated diene compound containing epoxy. 7. The resin composition according to claim 1, wherein the epoxy equivalent of the epoxidized diene-based block copolymer is from 320 to 8,000. 8. A steel sheet having a resin film comprising the resin composition according to claim 1. 9. The resin composition according to claim 1, wherein one surface of the steel sheet is coated with a film comprising the silica-containing resin composition of the resin composition according to claim 1; Of which
A steel sheet having a coating made of a resin composition containing metal powder. 10. The steel sheet having a resin film according to claim 1, wherein a steel sheet having a metal plating layer is used. 11. The steel sheet having a resin film according to claim 10, wherein the metal plating layer has Zn or Zn as a lowermost layer or a metal plating layer mainly composed of Fe as an upper layer. 12. The steel sheet having a resin film according to claim 1, further comprising a chromate film as an upper layer of the metal plating layer. 13. A tank using a steel sheet having the resin film according to claim 8. 14. The resin composition according to claim 1, which has a coating made of a resin composition containing silica on the outer surface, and the resin composition according to claim 1 on the inner surface. A tank using a steel sheet, characterized by having a coating made of a resin composition containing metal powder.