JPH01295843A - Precoated steel plate for two-piece can - Google Patents

Abstract

PURPOSE:To form a film excellent in a stopping property generating no release or damage even when DI molding is performed at a high speed, by forming a film composed of thermosetting paint containing an internal lubricant to one surface to become the outer surface of a can while forming a film composed of aluminum powder-containing thermosetting paint to the other surface to become the inner surface of the can. CONSTITUTION:When a film composed of thermosetting paint containing an internal lubricant is formed to one surface to become the outer surface of a can of a steel plate, a lubricating property is imparted to the film by the internal lubricant and excellent DI moldability can be imparted to the steel plate by said film. When a film composed of aluminum powder-containing thermosetting paint is formed to the other surface having to become the inner surface of the can of the steel plate, the softening temp. and hardness of the film are enhanced and, therefore, even when ironing is applied at a high molding speed of 100m/min or more and processing or friction heat is generated, the film is not softened and, as a result, the release or damage of the film is prevented and a stopping properly can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a pre-coated steel sheet for two-piece cans, which is used to manufacture a two-piece can body consisting of a can body and an upper lid.

[Conventional technology]

The body of a DI can, which is a type of two-piece can, is conventionally manufactured by DI molding, which includes the following steps. A circular plate cut out from a metal plate is forced to pass through a die using a punch to form a cup by drawing the circular plate, and then the thus formed cup is separately The cup is redrawn and ironed by forcing and successively passing it through a plurality of separate dies using a cutter, thus
To obtain a can body having a wall thickness thinner than that of a circular plate.

Similarly, the can body of a grained can, which is a type of two-piece can, has conventionally been manufactured by DRD molding, which is a method for molding grained cans, for example, by DRD molding, which includes the following steps. A circular plate cut from a metal plate is forced to pass through a die using a punch to form a cup by drawing the circular plate.The thus formed cup is then passed through a die using another punch. 6. Redraw the cup by forcing it through a plurality of separate dies, thus obtaining a can body with a wall thickness approximately equal to that of the circular plate.

Two-piece cans, such as the DI cans or shiboshi cans mentioned above,
Compared to so-called three-piece cans, which consist of a top lid, a bottom lid, and a body prepared by soldering or welding, the can body can be made thinner, making it lightweight, and there is no seam in the body. Therefore, the contents inside the can will not leak due to corrosion of the can body. Because of these advantages, two-piece cans are in high demand, and their uses are expected to expand.

As the metal plate for two-piece cans, a tin-plated steel plate or an aluminum plate is generally used. Tin plated steel plate is
Demand for two-piece cans made of tin-plated steel sheets is expected to increase because they are cheaper than aluminum sheets.

However, due to the recent shortage of tin supply and the rise in the price of tin, an increase in the manufacturing cost of tin-plated steel sheets and two-piece cans made of tin-plated steel sheets is unavoidable.

Therefore, it is strongly desired to reduce the manufacturing cost of tin-plated steel sheets.

The reduction rate of the wall thickness of the side wall of the DI can body is extremely large, about 70%, due to the effect of ironing.

Therefore, it is necessary to provide lubricity to the surface of the steel plate in advance. The tin plating layer of the tin-plated steel sheet provides excellent lubricity to the steel sheet. However, if the amount of attached tin plating layer is reduced in order to reduce the manufacturing cost of tin-plated steel sheets, the lubricity decreases, resulting in poor DI formability. For this reason, when the can body passes through the die during ironing, the can body may seize on the die due to frictional heat, or the can body may warp. -Furthermore, rust is likely to occur on the surface of the DI can body after removing oils and fats such as external lubricants that adhere to the surface of the DI can body during ironing.

[Problem to be solved by the invention]

The following method has been disclosed as a method for solving the above-mentioned problem.

(1) JP-A-51-63,787 Any one of epoxyphenol-based, epoxy-urea-formaldehyde-based, and vinyl organosol-based paints, or an internal lubricant such as wax or lanolin added to the above paints. A can body (hereinafter referred to as prior art 1) made of a pre-coated metal plate formed by coating a paint on at least one surface of the metal plate and then partially baking it.

(2) JP-A No. 60-4,753 An epoxyphenol paint or a paint prepared by adding an internal lubricant such as a fatty acid ester, wax, or a polymer compound to the above paint is applied to both surfaces of the surface-treated steel sheet. After coating,
DI can manufacturing method C, which consists of partially baking, then DI forming a pre-coated steel plate having such a coating, and then completely baking the coating. Below, Prior Art 2
).

(3) Japanese Patent Publication No. 5B-18229 A paint obtained by adding a specified ratio of olefinic hydrocarbon to a specific epoxyphenol paint is applied to at least one part of the steel plate.
A pre-coated steel plate for DI cans (hereinafter referred to as prior art 3), which is coated on one surface and completely baked.

(4) JP-A-57-168961 A pre-coating paint (hereinafter referred to as prior art 4) in which an internal lubricant such as wax, lanolin, or petrolatum is added to a specific vinyl chloride organosol paint.

According to the pre-coated steel sheets of Prior Art 1 to 3 and the pre-coated paint of Prior Art 4 described above, the DI formability can be improved to some extent by incorporating an internal lubricant.

However, in prior arts 1 to 4, DI is still not practical.
It cannot be said that the moldability is sufficient, the coating is damaged during DI molding, and deterioration of corrosion resistance is unavoidable.

As a means to solve the above-mentioned problem,
No. 51'72 discloses a two-piece precoated steel plate for cans (hereinafter referred to as prior art 5) consisting of the following.

(2) A precoated steel sheet for two-piece cans, on at least one surface of which a film of thermosetting paint containing an internal lubricant made of a hydrocarbon wax modified with a fluorine atom-substituted olefin is formed.

■ On one surface of the steel plate that will be the outer surface of the two-piece can,
A film of a thermosetting paint containing the internal lubricant is formed, and a film consisting only of the thermosetting paint not containing the internal lubricant is formed on the other surface of the steel plate that is to become the inner surface of the two-piece can. A pre-painted steel sheet for two-piece cans.

According to the prior art 5 described above, a precoated steel sheet for two-piece cans having excellent DI formability can be obtained.

However, the reason why such excellent DI formability is achieved is due to the forming speed (
This is a case where the punching speed) is, for example, as low as about 30 m/min.

If the molding speed is increased to, for example, 100m7 minutes or more and ironing is performed at high speed, the following problems will occur.

That is, the pre-coated film is softened by processing heat during ironing and frictional heat due to friction between the punch and the inner surface of the can body, and as a result, the softened film adheres to the punch. For this reason, when the punch is pulled out from the can body, the coating on the inner surface of the can body is peeled off or damaged, and as a result, the end of the can body gets caught on the stopper, compressing the can body, and buckling the side wall of the can body. occurs, and the so-called stripping property deteriorates. Additionally, the corrosion resistance of the molded two-piece can is degraded due to delamination or damage to the precoated coating.

Therefore, an object of the present invention is to form a film on its surface that has excellent DI moldability and corrosion resistance, does not cause peeling or damage even when DI molded at high speed, and has excellent strippability. , to provide a prepainted steel sheet for two-piece cans.

[Means to solve the problem]

From the above-mentioned viewpoints, the present inventors have developed a coating on the surface that has excellent DI moldability and corrosion resistance, does not cause peeling or damage even when DI molded at high speed, and has excellent stripping properties. We conducted extensive research to develop a pre-coated steel sheet for two-piece cans. As a result, a film of thermosetting paint containing an internal lubricant is formed on one surface, which is to become the outer surface of the can, and a thermosetting paint containing aluminum powder is formed on the other surface, which is to become the inner surface of the can. It has been found that the steel sheet on which the coating is formed is optimal as a pre-coated steel sheet for two-piece cans having the above-mentioned performance.

This invention was made based on the above-mentioned knowledge,
In a pre-coated steel plate for a two-piece can, in which a film of a thermosetting paint containing an internal lubricant is formed on at least one surface of the steel plate, one surface of the steel plate that is to become the outer surface of the two-piece can, A film of thermosetting paint containing the internal lubricant is formed, and a film of thermosetting paint containing aluminum powder is formed on the other surface of the steel plate, which is to become the inner surface of the two-piece can. It is characterized by the fact that it is

In this invention, the reason why a film of thermosetting paint containing an internal lubricant is formed on one surface of the steel plate, which is to be the outer surface of the can, is that the internal lubricant gives the film lubricity;
This is to impart excellent DI formability to the steel sheet.

Furthermore, the reason why a film of thermosetting paint containing aluminum powder was formed on the other surface of the steel plate, which was to become the inner surface of the can, was as follows. That is, the aluminum powder increases the softening temperature and hardness of the coating, thereby increasing the
Even when ironing is performed at a fast molding speed of 7 m or more and processing heat and frictional heat are generated, the film does not soften, thereby preventing peeling and damage of the film and improving stripping properties. be able to.

Furthermore, in order to improve the stripping property, an aluminum-containing coating is uniformly present on the inner surface of the formed can, and the sacrificial anticorrosive action of this aluminum can improve the corrosion resistance of the can. .

The thermosetting paints that make up the films formed on both surfaces of the steel plate include vinyl chloride organosol paints, epoxy/phenol paints, epoxy/amino paints, polyester/amine paints, and epoxy/acrylic paints. and conventionally known can paints such as epoxy ester/amino paints.

Among the above, preferred paints are vinyl chloride organosol paints. This vinyl chloride organosol paint is
with a molecular weight of about 10,000 to 100,000 and 0.5
It is obtained by adding and dispersing fine particles of vinyl chloride resin having a particle size of ~10 μm into a solvent in which a phenol resin and/or an epoxy resin is dissolved at a predetermined ratio.

In addition to the above, epoxy/phenol paints containing bisphenol A type epoxy resins and epoxy/amine paints are also preferred as thermosetting paints for the film formed on the other surface of the steel plate, which is to become the inner surface of the can.

The internal lubricant contained in the thermosetting paint for the coating formed on one surface of the steel plate, which is to become the outer surface of the can, is as follows:
Any material may be used as long as it is solid at room temperature and can impart lubricity to the surface of a cured film when incorporated into a thermosetting paint, such as mineral waxes such as paraffin wax, Synthetic waxes such as polyethylene and animal or vegetable waxes are used.

A preferred internal lubricant is a polytetrafluoroethylene modified hydrocarbon wax. Polytetrafluoroethylene-modified hydrocarbon wax is produced by mixing hydrocarbon wax particles and polytetrafluoroethylene fine particles in a powerful mixer such as a jet mill. It is obtained by attaching fine particles of polytetrafluoroethylene to. Such polytetrafluoroethylene-modified hydrocarbon waxes are available under the trade names "Lanco Wax TKF177B and TKF
It is commercially available as l'i'80 j (manufactured by George M., Langer and Company).

The content of the internal lubricant in the thermosetting paint is preferably in the range of 0.1 to 30 parts by weight based on 100 parts by weight of the solid resin in the thermosetting paint.

If the content of the internal lubricant is less than 0.1 part by weight, the improvement in DI formability of the steel sheet will be insufficient. On the other hand, if the content of the internal lubricant exceeds 30 parts by weight, the chicken trobby property increases, which not only deteriorates the paintability of the paint, but also
It is also disadvantageous in terms of cost.

The aluminum powder contained in the thermosetting paint for the coating formed on the other surface of the steel plate, which is to become the inner surface of the can, is in the form of flakes and has an average particle size of 0.5 to 3.
It is preferably within the range of 5 μm. If the average particle size of the aluminum powder is less than 0.5 μm, the cost will be high and it is not practical. On the other hand, the average particle size of aluminum powder is 35μ
If the thickness exceeds m, the thickness of the coating greatly exceeds the preferred thickness described below, causing unevenness on the surface of the coating, difficulty in peeling off the coating during DI molding, and deterioration of corrosion resistance.

Flake-like aluminum powder consists of scale-like particles, and is classified into non-leafing type and leafing type depending on its properties. Leafing type aluminum powder has the property of gathering in large numbers near the surface of the coating and arranging parallel to the surface of the coating when it is blended into the coating. Therefore, in the present invention, it is preferable to use leafing type aluminum powder as the flaky aluminum powder. That is, if leafing type aluminum powder is used, stripping properties can be obtained with a small amount compared to non-leafing type aluminum powder, and favorable results such as excellent gloss after molding can be obtained.

The content of aluminum powder in the thermosetting paint is preferably in the range of 10 to 400 parts by weight based on 100 parts by weight of the solid resin in the thermosetting paint. If the content of aluminum powder is less than 10 parts by weight,
It is not possible to impart excellent stripping properties and corrosion resistance to steel sheets. On the other hand, if the content of aluminum powder exceeds 400 parts by weight, "streaks" or "scratches" will occur on the surface of the coating during eveninging during DI molding.
The coating will peel off easily. A preferred content ratio of aluminum powder is 10 to 200 parts by weight based on 100 parts by weight of resin as solid content in the thermosetting paint.

Even if the substrate of the prepainted steel sheet of this invention is a surface-treated steel sheet plated with tin, nickel, chromium, etc.,
Alternatively, a cold-rolled steel sheet without surface treatment may be used. In particular, chrome-plated steel sheets are preferable because they have good corrosion resistance and good adhesion of pre-coated films.

When a surface-treated steel sheet is used as a substrate, the plating layer is protected by a pre-coated film, so the plating layer does not come into direct contact with the die during DI molding. Therefore, even after DI molding, the plating layer is maintained in a uniform state.

The coating is formed on the surface of the steel plate by applying the above-mentioned paint to the surface of the steel plate and then baking it. The conditions for baking the film are not particularly limited.
For example, heating the coating by blowing hot air at a temperature of 150 to 400°C for 10 seconds to 10 minutes,
The coating may be baked completely.

The thickness of the coating formed on each of both surfaces of the steel plate is preferably within the range of 1 to 10 μm per side of the steel plate. If the thickness of the coating is less than 1 μm, the coating will break during DI forming of the steel plate, and the continuity of the coating will not be maintained. Therefore, D of the steel plate
I moldability is poor, and in the worst case, "galling" occurs during DI molding. On the other hand, if the thickness of the coating exceeds 10 μm, not only is a so-called build-up phenomenon likely to occur during DI forming of a steel plate, but it is also disadvantageous in terms of cost.

In a can manufactured using the pre-coated steel sheet of the present invention, the pre-coated film can be uniformly present on the inner and outer surfaces of the can due to the improved DI formability of the steel sheet. Therefore, depending on the contents to be filled in the can, it is not necessary to form a top coating on the inner and outer surfaces of the can.

If the contents to be filled in the can are liquids that corrode the can, or if the taste and aroma are particularly important, a well-known top coat containing a vinyl chloride resin is applied to the inner surface of the can. You may also apply paint. In addition, in the paint for the coating formed on one surface of the steel plate that is to become the outer surface of the can,
A pigment such as titanium white may be added for coloring.

Next, the prepainted steel sheet of the present invention will be explained in more detail by way of examples, while being compared with a prepainted steel sheet that is outside the scope of the present invention.

〔Example〕

A paint NILI~18° for preparing a precoated steel sheet according to the present invention and a precoated steel sheet outside the scope of the present invention was prepared as follows.

1. Paint N11l The following materials were prepared as materials for Paint Ugly 1.

(1) Thermosetting paint (vinyl chloride resin organosol paint) (a) Vinyl chloride paste resin: 4 oti part Product name: Sumiritz) Ex-13 (Sumitomo Chemical Co., Ltd. (b) Phenol resin: 16 overlap Product name: Hytanol 4
020 (Hitachi Chemical Co., Ltd. (c) Vinyl chloride/vinyl acetate/maleic acid copolymer: 40 parts by weight Product name: Vinylye) VMCC (manufactured by Union Carbide) (d) Bisphenol A epoxy resin: 4 parts by weight Product name : Ebicoat 828 (manufactured by Yuka Shell Epoxy Co., Ltd.) (2) Aluminum powder: Solid content in thermosetting paint 10
30 parts by weight per 0 parts by weight (Product name: Alpace) 55-574 (manufactured by Toyo Aluminum Co., Ltd.) (Non-leafing type aluminum lamb powder approximately 66 wt, high content) Of the above (1), phenolic resin, vinyl chloride・Vinyl acetate-maleic acid copolymer and bisphenol A type epoxy resin were mixed with 40 vt, % xylene, 30
wt,% selonlupe acetate and 30vt,%
The vinyl chloride paste resin of (1) above and the aluminum powder of (2) above are added to the resulting solution while stirring at high speed, and these are dissolved in a mixed solvent consisting of diisobutyl ketone. Thus, a paint grade 1 having a solids content of about 4 owt.% and a viscosity of about 100 seconds (measured temperature: 25° C., Ford cup: floor 4) was prepared.

2. Paint height 2 (vinyl chloride resin organosol paint) In the paint level 1 mentioned above, the content of aluminum powder was 50 parts by weight per 100 parts by weight of solid content in the thermosetting paint. Paint Ugly 2 having the same component composition as Ugly 1 was prepared.

3. Paint N15 (vinyl chloride resin-based organosol paint) The paint N Paint Taki 3 having the same component composition was prepared.

4. Paint level 4 (vinyl chloride resin organosol paint) Paint N mentioned above
Paint F&L4 having the same component composition as Paint No. 1 except that the content of aluminum powder in a1 was 200 parts by weight based on 100 parts by weight of solid content in the thermosetting paint.
was prepared.

5. Paint Nf15 (vinyl chloride resin organosol paint) Paint NIL1 was used in paint No. 1 mentioned above, except that the content of aluminum powder was 400 parts by weight based on 100 parts by weight of the solid content in the thermosetting paint. Paint Na5 having the same component composition as
was prepared.

6. Ugly paint 6 The following materials were prepared as materials for paint Na6.

(1) Thermosetting paint (epoxy/phenol paint) (a) Bisphenol A epoxy resin: 8 (4f
Product name: Epicoat 1009 (manufactured by Yuka Shell Epoxy Co., Ltd.) (b) Phenol resin: 20 parts by weight Product name: Hytanol 4020 (manufactured by Hitachi Chemical Co., Ltd.) (2) Aluminum powder: Solid content in thermosetting paint 30 parts by weight per 100 parts by weight Product name: Alpace) 55-574 (manufactured by Toyo Aluminum Co., Ltd.) (Aluminum powder approximately 66 wt, containing q6) Above (1
) of bisphenol A type epoxy resin and phenolic resin in l 2 vrL% xylene, 55vt, %
of selonlupe acetate, low weight, % N-butanol and 23 wt, % cyclohexanone, and in the resulting solution, the above (2) was dissolved.
of aluminum powder was added while stirring at high speed to disperse it into the solution, thus reducing the solids content to about 35 wt.
, %, and a viscosity of 70 seconds (measured temperature: 25° C., 1 Ford cup grade 4). Paint N[16 was prepared.

7. Paint N117 The following materials were prepared as materials for paint Na7.

(1) Thermosetting paint (epoxy/amine paint) (a) Bisphenol A type epoxy resin: 90 parts by weight Product name: Epicoat 1007 (manufactured by Yuka Shell Epoxy Co., Ltd.) (b) Urea formaldehyde resin: 10 parts by weight Product name: Melan 11E (manufactured by Hitachi Chemical Co., Ltd.) (2) Aluminum powder 30 parts by weight per 100 parts by weight of solid content in the dithermosetting paint Product name: Alpaste 55-574 (manufactured by Toyo Aluminum Co., Ltd.) ) (Aluminum powder containing about 66 vrt, %) The bisphenol A type epoxy resin and urea formaldehyde resin of (1) above were mixed with l 5 wt, % diacetone alcohol, 7 wt, % calpitol and 75 wt,
% ethyl cellosolve, dissolved in a mixed solvent consisting of
The aluminum powder described in (2) above was added to the obtained solution while stirring at high speed and dispersed in the solution, so that the solid content was approximately 35 wt, the viscosity was 60 seconds (measured temperature: Paint No. 7 was prepared at 25° C. in a food cup.

8 Paint Ugly 8 (Vinyl chloride resin-based organosol paint) Paint 8 having the same composition as Paint No. 1 was prepared, except that no aluminum powder was added.

9. Paint magnetic 9 (epoxy/phenol paint) Paint N11 except that aluminum powder is not added
Paint Na9 having the same component composition as Example 6 was prepared.

10, Paint Na 10 (epoxy/amine paint) Paint F&L except that aluminum powder is not added
Paint No. 10 having the same component composition as '7 was prepared.

11.Paint MILLI The following materials were prepared as materials for Paint No. 11.

(1) Thermosetting paint (vinyl chloride resin-based organosol paint) (a) Vinyl chloride paste resin: 45 parts by weight Product name: Sumilit EX-13 (Juju Kagaku Co., Ltd. (b) Phenol resin: 10 parts by weight Product name: Hytanol 4020
(Hitachi Chemical Co., Ltd. (c) Oil-free alkyd resin: 25 parts by weight Product name: Almatex P-646 (
(manufactured by Mitsui Toatsu Co., Ltd.) (d) Polyester plasticizer: 20 parts by weight (
2) Internal lubricant polytetrafluoroethylene modified polyethylene wax: 10 parts by weight per 100 parts by weight of solid content in thermosetting paint Product name: Lanco Wax TF l Tsuma 8 (Joke M
・Made by Langer & Co.) Melting point: 100-110°C (3) Organotin stabilizer: Vinyl chloride paste resin 10
1.6 parts by weight per 0 parts by weight Of the above (1), the phenol resin, oil-free alkyd resin, and polyester plasticizer, and the organotin stabilizer of the above (3) were combined at 40 wt%. xylene, 3o
wi, % cellosolve acetate and 30wt,
The above (1) vinyl chloride paste resin and the above (2) polytetrafluoroethylene modified polyethylene wax were dissolved in a mixed solvent consisting of diimbutyl ketone (96%) and stirred at high speed into the resulting solution. to disperse them in solution, thus
Solid content approximately 45 wt, viscosity 90 seconds (measurement temperature = 25
℃, Ford Cup Ugly 4) Paint No. 11 was prepared.

12. Paint m 12 (Vinyl chloride resin-based organosol paint) Paint N1112 having the same component composition as Paint Floor 11 was prepared, except that no internal lubricant was added.

13. Paint 1 @ 13 (Vinyl chloride resin organosol paint) The following internal lubricant was used instead of polytetrafluoroethylene modified polyethylene wax in the paint hall.
Paint store 13 having the same component composition as paint store 11 was prepared.

Internal lubricant; Polyethylene wax; 10 parts by weight per 100 parts by weight of solid content in thermosetting paint Product name: AC polyethylene 68o (manufactured by Allied Corporation) 14, Paint flat 14 (vinyl chloride, resin-based organosol paint) Paint Haruka 14 had the same composition as Paint Boiled 1, except that the following was used as the aluminum powder in Paint A1 described above.
was prepared.

Aluminum powder product name: Alpaste 0200M (manufactured by Toyo Aluminum Co., Ltd.) (Leafing type aluminum powder approximately 65 wt, high content) 15. Paint boiled 15 (vinyl chloride resin organosol paint) Paint A mentioned above
The leafing type aluminum powder used in Paint A14 was used as the aluminum powder in No. 1, and the aluminum powder content was 50 parts by weight based on 100 parts by weight of the solid content in the thermosetting resin. Paints &15 were prepared with the same component composition.

16, Paint l616 (vinyl chloride resin organosol paint) Paint A mentioned above
In addition to using the aluminum powder in paint & 14 as the aluminum powder in 1 and using flying type aluminum powder, and setting the content of aluminum powder to 100 parts by weight based on 100 parts by weight of solid content in the thermosetting resin, Paint boiler 16 having the same component composition as paint store 1 was prepared.

The following surface-treated steel plates and non-surface-treated steel plates were prepared as steel plates to be coated with the above-mentioned paint.

1 Surface treated steel sheet A (electrolytic chromate treated steel sheet) Both surfaces of a low carbon cold rolled steel sheet with a plate thickness of 0.3W were cleaned by ordinary electrolytic degreasing and electrolytic pickling, and then,
The above-mentioned steel plate was subjected to cathodic electrolytic treatment under the following conditions, and a layer of 50 m97n per side was applied to each of both surfaces of the steel plate.
15 per side on the metallic chromium layer.
a;)/lr? of hydrated chromium oxide layer was formed.

(1) Bath composition Chromic anhydride (cro): toy/11
Ammonium fluoride (NH4F): 2°02/1
(2) Bath temperature: 50°C (3) Current density: 30A/drr? (4
) Processing time: 1 second Surface-treated steel sheet B (electro-nickel-plated steel sheet) Both surfaces of a 0.3-thick low-carbon cold-rolled steel sheet were cleaned by ordinary electrolytic degreasing and electrolytic pickling, and then the following conditions were applied. Then, the above-mentioned steel plate was subjected to electro-nickel plating treatment,
A nickel plating layer was formed on each of both surfaces of the steel plate in an amount of No. 50/9 on each side.

(1) Composition of the bath Nickel sulfate: 240 liters/liter Nickel chloride: 45 liters/liter oxalic acid
: 3 (1/ tartaric acid :
309/l Ammonium fluoride: 159/l
1 (2) Bath temperature: 50'C (
3) Current density: 5A/di (4
) Treatment time: 1 second Next, the low carbon cold rolled steel sheet with nickel plating layers formed on both surfaces as described above was subjected to cathodic electrolysis treatment under the following conditions,
On the surface of the nickel plating layer, 15In9/- per side
Formed an amount of water-containing chromium oxide layer.

(1) Bath composition Chromic anhydride (CrO8): 30 f/
L (2) Bath temperature: 50°C (3)
Current density: 10 A/dnl (4) Processing time: 1 second Surface treated steel sheet C (electro-tin plated steel sheet) Both surfaces of a low carbon cold rolled steel sheet with a thickness of 0.3 mm were subjected to regular electrolytic degreasing and electrolytic pickling. Then, the above-mentioned steel plate was subjected to electro-tinning treatment under the following conditions to form a tin plating layer of a, 3 cy/rrl per side on each of both surfaces of the steel plate.

(1) Bath composition Tin (Sn”): 309/L Free acid (converted to sulfuric acid): 15 f/L Ethoxynaphthol sulfonic acid: 59/1 (2) Bath temperature: 40°C (3) Current density
:6A/dm” (4) Processing time
: 1 second Next, the low carbon cold rolled steel sheet with tin plating layers formed on both surfaces as described above was subjected to cathodic electrolytic treatment under the following conditions, so that on the surface of the tin plating layer,
15 m9/n per side? A layer of hydrated chromium oxide was formed in an amount of .

(1) Bath composition Chromic anhydride (cro3): 30 y
/L (2) Bath temperature: 50℃ (
3) Current density: 10 A/a
n? (4) Processing time: 1 second■
Surface treated steel sheet D (Electro tin plated steel sheet) Under electric tin plating treatment conditions, current density is 30A/dF71
A surface-treated steel sheet that is the same as surface-treated steel sheet C, except that the treatment time is 2 seconds and the amount of tin plating layer formed on each of both surfaces of the steel sheet is 5.6 f/m per side. A sample was prepared.

■ Steel plate (E) without surface treatment (low-carbon cold-rolled steel plate with a plate thickness of 0.3 m) Using the above-mentioned paints N11l to 16 and the above-mentioned steel plates A to E, pre-coated steel plate C of the present invention was prepared. Examples 1 to 14 (hereinafter referred to as "inventive steel sheets") and Nos. 1 to 7 (hereinafter referred to as "comparative steel sheets") which were outside the scope of the present invention were prepared as shown in Table 1.

In addition, each of the above-mentioned steel sheet of the present invention and steel sheet for comparison,
Any of the above-mentioned paints is applied to a thickness of 5 μm on both surfaces of a steel plate using a roll, and then the paint film thus formed is heated at 205°C in a box-shaped heating furnace.
It was prepared by baking for 10 minutes at a temperature of .

Table 1 The DI formability, stripping property, and corrosion resistance of each of the steel plates of the present invention Ugly 1 to 14 and comparative steel plates Nnl to 7 shown in Table 1 were evaluated by the performance tests described below. The results of the evaluation are shown in Table 2.

(1) DI formability First, according to the conventional DI forming described above, the steel sheet I of the present invention was formed.
Can bodies of DI cans were prepared from circular plates having a diameter of 123 m cut from each of &L1 to 11 and comparative steel plates N111 to 7. That is, by forcing the circular plate through a die using a punch, draw ink was applied to the circular plate to form an inner diameter of 72 m and a diameter of 36 w.
A cup with a height of l1 was formed. The cup thus formed is then punched 1o' using another punch.
The cup was redrawn and ironed in three stages by forcing and successively passing through several separate dies at a punch speed of 52+ m/min and a punch stroke of 500 m/min. A can body of a DI can was obtained having an inner diameter and a height of 130 cm. The reduction rate in each of the three stages of ironing is 30%.
, 28 chi and 24%.

During redrawing and ironing,
A conventional external lubricant at a temperature in the range of 00° C. was supplied to the gap between the die and the cup outer surface, and the gap between the punch and the cup inner surface.

DI formability is determined by measuring the forming load at each reduction in the three stages of ironing during DI forming of a can body using a load cell attached to the punch, and then measuring the forming load at each reduction in each of the three stages of ironing from the punch stroke. The energy is calculated by the following formula, W = f P, f, ds However, in the above formula, E: forming energy, P: forming load, t: gravitational acceleration, and ds: variation amount of punch stroke. Then, calculate The values of forming energy (E) calculated in this way in the three steps of reduction of ironing are summed, and the total amount of forming energy (g) obtained in this way is used as a reference. It was evaluated by using It goes without saying that the smaller the total amount of forming energy mentioned above is, the better the DI formability is.

(2) Stripping property Stripping properties are defined as the pullout load applied to the punch when the punch is pulled out from the molded can body when the can body is prepared according to the DI molding described in (1) above. was detected and evaluated based on the detected pull-out load. It goes without saying that the smaller the pull-out load, the better the stripping properties.

(3) Corrosion resistance A normal degreasing solution at pH 8.5, concentration 2 Vt,%, temperature 50°C was sprayed for 2 minutes on both the inner and outer surfaces of the can body prepared according to DI molding described in (1) above. External lubricant deposited on both surfaces of the can body was removed. Next, a 20 vrt, % solution of top coat paint (vinyl chloride/vinyl acetate/maleic acid copolymer, trade name: Vinyrite VMCH, manufactured by Union Carbide) (solvent: 1:1 mixed solvent of methyl ethyl ketone and xylene) was added. ), 205
Baked for 3 minutes at a temperature of °C.

Regarding corrosion resistance, the inner surface of the can body is
Cutting corrosion resistance (hereinafter referred to as “U resistance”)
(referred to as “CC property”) and 1ron pickup resistance.
The properties (hereinafter referred to as "IP resistance") were evaluated by the performance test described below.

(a) under cutting corros
ion test under cutting corros
The ion test was conducted as follows. From each of the can bodies prepared as described above, 50 + m x 70
A specimen with dimensions of rms was taken. A cross-shaped notch reaching the substrate was made on one side of the test piece corresponding to the inside surface of the can body, and adhesive tape was applied to the other side of the test piece corresponding to the outside surface of the can body and the edges of the test piece. The other side and edges of the pieces were sealed. Next, the test piece was 1.
It was immersed for 96 hours in a test solution containing 5 wt.% citric acid and 1.5 wt.% sodium chloride at a temperature of 38°C. Next, adhesive tape was applied to the cross-shaped notches on one side of the test piece, and then the adhesive tape was peeled off. The UCC resistance was evaluated by examining the corrosion width of the cross-shaped notches and the peeling state of the pre-coating and top coating. The evaluation standard is a first-order standard.

◎: Very good O: Excellent Δ: Slightly poor (b) 1ron pickup test: 1ron p
The ickup test was conducted as follows. In each of the can bodies prepared as described above, 250 cc.
amount of Pepsi cola was filled into the can, and a top lid was attached to the can body to airtightly seal the can. The cans filled with Pebsi Cola were then left at a temperature of 38°C for 6 months, and
The amount of Fe ions eluted from the can into Pepsi-Cola was measured by atomic absorption spectrometry to evaluate IP resistance.

Table 2 As is clear from Table 2, paint N [1
Comparative steel plates Ugly 1 to 3 and Grade 5 on which coatings of 8 to 10 and m12 were respectively formed, on the other surface of the steel plate,
ml of paint containing internal lubricant instead of aluminum powder
Comparative steel sheets N [L4 and Ugly 6 were formed with coatings of L and Nn13, respectively, both of which had poor stripping properties, and the comparative steel sheets of 1 m2 to 6, which were special cases, buckled and formed when the punch was pulled out. I couldn't. Comparative steel plate N117, which is an electro-tin plated steel plate on which no paint film is formed, has poor DI formability, stripping property, and UCC resistance.

On the other hand, steel plates Nos. 1 to 14 of the present invention were all excellent in DI formability, stripping property, and corrosion resistance.

Although the above-mentioned embodiment describes the case where DI cans are manufactured by DI forming, the precoated steel sheet of the present invention can also be used when manufacturing squeezed cans by squeezed forming, and excellent effects are exhibited.

〔Effect of the invention〕

As detailed above, the pre-coated steel sheet for two-piece cans of the present invention has excellent DI formability and corrosion resistance, and the pre-coated film will not peel or be damaged, especially even when DI formed at high speed. It has excellent stripping properties. As described above, the present invention brings about many industrially useful effects.

Claims (1)

[Claims] 1. A pre-coated steel plate for a two-piece can, in which a film of thermosetting paint containing an internal lubricant is formed on at least one surface of the steel plate, which is to be the outer surface of the two-piece can. A film of thermosetting paint containing the internal lubricant is formed on one surface of the steel plate, and a film of thermosetting paint containing aluminum powder is formed on the other surface of the steel plate, which is to become the inner surface of the two-piece can. A precoated steel sheet for two-piece cans, characterized by being coated with a curable paint. 2. The content ratio of the aluminum powder is 10 parts by weight based on 100 parts by weight of the resin as solid content in the thermosetting paint.
The precoated steel sheet for a two-piece can according to claim 1, wherein the amount is in the range of 400 parts by weight. 3. Claim 1, wherein the aluminum powder is in the form of flakes.
A pre-coated steel plate for two-piece cans as described in . 4. The precoated steel sheet for a two-piece can according to claim 3, wherein the flaky aluminum powder is of a leafing type. 5. The content ratio of the internal lubricant is 0.1 to 3 parts by weight based on 100 parts by weight of the resin as solid content in the thermosetting paint.
The precoated steel sheet for two-piece cans according to claim 1, wherein the precoated steel sheet is within the range of 0 parts by weight. 6. The precoated steel sheet for a two-piece can according to claim 1, wherein the internal lubricant is a polytetrafluoroethylene-modified hydrocarbon wax. 7. The thickness of the coating formed on each surface of the steel plate is
The precoated steel sheet for a two-piece can according to claim 1, wherein the thickness is within the range of 1 to 20 μm per side of the steel sheet.