JP2001262371A - Laminated seamless cans - Google Patents

Abstract

(57) [Problem] To provide a high-quality film-coated steel two-piece can with high productivity. SOLUTION: The amount of adhesion on one side to both sides of a steel sheet is 20 to 2
000 mg / m ² , and the amount of C in the upper layer is 1 to 100 m
g / m ² having a chemical conversion coating mainly composed of an organic resin,
Further, a laminated seamless can obtained by drawing and ironing a laminated steel sheet having a polyester resin film thereon. The film on the inner surface of the can has (A) thickness 1
0 to 45 μm, melting point: 215 to 245 ° C., cold crystallization heat: 8.5 to 35.0 J / g, (B) thickness: 5 to 20 μm, melting point: 235 to 260 ° C. It is coated so as to be in contact with the steel plate, and the entire film is amorphized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester resin-coated seamless can made of steel.

[0002]

2. Description of the Related Art Metal cans and containers made of steel or aluminum are roughly classified into three-piece cans and two-piece cans according to their shapes. Three-piece cans,
Since it is made of a canopy, it is called a three-piece can. Since the method of body making is currently mainly seam welding and bonding, inexpensive steel is used. On the other hand, a two-piece can is an integrated body with a canopy and a can body.It is also called a two-piece can or a seamless can because there is no joint in the can body because it consists of a canopy. Is used. In the case of metal cans, those coated on the inner surfaces of the cans in order to ensure corrosion resistance are used. In recent years, laminated cans having laminated thermoplastic resin films have been developed and are on the market. Laminated cans are mainly ones in which a metal material is coated with a thermoplastic resin film and then can body molding is performed. In particular, a highly sophisticated molding technique is required to obtain a seamless can.

[0003] In this sense, a technology relating to a seamless laminate can is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-2241.
Japanese Patent Application Laid-Open Nos. Hei 7-195615 and Hei 8-24475
No. 0 publication and the like have been proposed and disclosed. The merits of laminated cans, from the consumer's point of view, depend on the thermoplastic resin film to be applied, but the primary point is that they have excellent content resistance, especially excellent flavor, such as the taste and flavor of the contents. Has been raised. On the other hand, as a disadvantage, this time from the can manufacturer side, as described above, in the case of a two-piece can, the degree of processing (or degree of deformation) of the thermoplastic resin film-coated metal plate is large, so the inner side of the can at the time of molding. If the resin film is damaged, the quality of the inner surface of the can cannot be ensured.Therefore, it is necessary to strictly inspect the quality of the can body, and the product yield is inferior to the current painted can. Can be raised. Particularly, in the case of a laminated seamless can using a steel material, the above tendency is large.

[0004] Such a film defect of the resin film on the inner surface side of the laminated can is caused during the can forming process as described above.
Needless to say, this is an important technical issue in terms of product yield. On the other hand, in order to reduce the total can cost, reduction in the number of metal plates to be used and reduction in the diameter of an easy open end (EOE), which is a can lid, are being promoted. Speaking of the easy opening can lid, for example, when the can body is a 350 ml beer can, it is generally called 211, the inner diameter of the can body is about 65.9 mm, and of course, the can lid to be wound is also for 211. Currently, can lids used for the can body are for 206 and 204, and further attempts are being made to use 202.

[0005] This inevitably results in a so-called diameter reduction in which the opening of the can body is reduced to a smaller diameter, so that not only the metal used for the can body but also the resin film coated on the surface thereof is reduced. It will be subjected to very severe processing. However, in the two-piece can forming process involving ironing, it is difficult for the thermoplastic resin film on the inner surface to peel off, scratch or other defects, especially when the processing rate is high, and neck processing and flange processing for high diameter reduction At present, there is no suitable film laminate material that can be formed without peeling the resin film and without forming any scratches or other defects.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a high-corrosion-resistant, high-quality resin-coated steel two-piece can having no film defects with a high yield. .

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method for producing a steel sheet having a Ni content of 20 to 2000 mg / m ^{2 on} both sides of a steel sheet.
1 to 100 as the amount of C deposited on one side of the plating layer and the upper layer
mg / m ² of a chemical conversion coating layer mainly composed of an organic resin, a polyester resin film on at least a side serving as an inner surface of the can, and a polyester resin film having a thickness of 10 to 45 μm and a melting point (ATm) of 215 to 245 ° C. (A) having a thickness of 5 to 20 μm and a melting point (BTm) of 235 to 260
° C, and the relation between the melting point (ATm) of the polyester resin film (A) and the melting point (BTm) of the polyester resin film (B) satisfies the relation of ATm <BTm. Total thickness is 1
A 5 to 50 μm two-layer polyester resin film, wherein the average density of the polyester resin film (A) and the polyester resin film (B) is less than 1.36 g / cm ³ ;
The polyester resin film (A) is drawn and ironed from a laminated steel sheet of a polyester resin film that is coated so as to be in contact with the steel sheet, and the molded body is heated and quenched to a temperature equal to or higher than the melting point of the polyester resin film, It is a laminated seamless can in which a polyester resin film is made amorphous. More preferably, the plate thickness of the can wall is 50 to 70 with respect to the plate thickness of the can bottom (original plate thickness).
%, And the molded body is heated and quenched to a temperature equal to or higher than the melting point of the polyester resin film, and the average density of the coated polyester resin film is 1.3.
It is a laminated seamless can which is less than 6 g / cm ³ and is amorphous.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the laminated seamless can of the present invention will be described in detail. First, the steel sheet according to the present invention will be described. The steel sheet in the present invention has a single-sided adhesion amount of 20 to 2000 mg / m on both sides.
² Ni plating layer, 1-sided C amount on one side
It has a chemical conversion coating layer mainly composed of 100 mg / m ² of an organic resin. The steel sheet before the Ni plating and the chemical conversion treatment is not particularly limited, and a steel sheet usually used as a steel sheet for cans is applied. However, when selecting, it is necessary to pay attention to the strength of the can body, especially the bottom pressure resistance.
If the carbonated beverage can is 18 kPa or more and the bottom pressure is not more than 686 kPa in a carbonated beverage can such as a cola, a phenomenon in which the bottom of the can protrudes outside the dome occurs.

In order to avoid this phenomenon, there is a relationship between the hardness and the bottom shape of the steel plate used, but it is difficult at present under the condition that the steel plate thickness is 0.15 mm or less. On the other hand, if the thickness of the steel plate is 0.22 mm, even if the hardness of the steel plate used is low, the phenomenon that the dome at the bottom of the can projects outward does not occur.
Therefore, the thickness of the steel sheet is preferably 0.15 to 0.22 mm. Next, the surface treatment of the Ni plating or the chemical conversion coating applied to the surface of the steel sheet will be described.

In the present invention, the reason why Ni is first adhered to the steel sheet surface will be described. In the case of a two-piece can obtained by drawing and ironing a steel sheet coated with a resin film as in the present invention, a metal plating film or a chemical conversion coating formed on the steel sheet surface is destroyed according to the degree of processing, and before processing. The characteristics of are reduced. As a surface-treated steel sheet when forming from a steel sheet having a resin film laminated thereon as in the present invention, TFS- which has been subjected to electrolytic chromic acid treatment for forming a metal chromium on a steel sheet and a hydrated chromium oxide on an upper layer thereof.
CT (tin-free steel chromium type) is well known, but even with such surface-treated steel sheets,
After the drawing-ironing process, a part of the surface treatment film is broken. As a result, thread-like corrosion may occur starting from a portion where iron is exposed, such as an opening of a can. Naturally, cans with thread-like corrosion lose their value as products, which is a problem.

[0011] Thread-like corrosion is named because the corroded portion grows in a thread-like manner, and it occurs in iron and aluminum, and the growth of the corrosion is driven by the reduction reaction of oxygen. Since the electrolytic chromic acid-treated film applied to the steel sheet described above is a film in which the reduction reaction of oxygen hardly occurs, if the film is sound, thread-like corrosion is extremely unlikely to occur. However, after the drawing-ironing process, a part of the surface treatment film is destroyed, so that thread-like corrosion occurs. Ni is known as a metal that does not cause thread-like corrosion, and coating an iron base with such a metal is effective in preventing thread-like corrosion of a steel sheet. However, similar to the electrolytic chromic acid-treated film described above, drawing and ironing are performed. After processing, the integrity of the film is no longer ensured,
In the present invention, the adhesion amount of Ni plating is ²⁰ to 2000 mg / m ² as the adhesion amount on one side.

If the lower limit is less than 20 mg / m ² , even at 50%, which is the minimum value of the reduction rate of the thickness of the can of the present invention, thread-like corrosion occurs, which is not preferable. In addition, the aforementioned 204
(About 54.9 mm inside diameter) and 202 (about 52.4 m inside diameter)
m) and the like, the coated polyester resin film may peel off during the necking process with a large diameter, which is not preferable. Further, when the Ni adhesion amount is less than the lower limit of 20 mg / m ² ,
Should a defect occur in the coating film on the inner side of the can,
Depending on the contents, there is a risk that the base iron is melted to form a perforated can, which is not preferable.

On the other hand, if the upper limit is more than 2000 mg / m ² , the effects such as the occurrence of thread-like corrosion and the securing of adhesion are saturated even at the maximum value of 70% of the reduction rate of the thickness of the can of the present invention. Therefore, it is necessary that the amount of Ni adhered is 20 mg / m ² or more.
The effect of the above is fully exhibited when the adhesion amount on one side is 10
It is desirable to apply Ni plating of 0 mg / m ² or more.
In addition, the presence of Ni on the steel plate surface of the outer surface of the can slightly improves the whiteness, the amount of white pigment mixed in the polyester resin film covering the outer surface side of the can, and the whiteness that occurs during printing and painting. There is also an economical effect that the amount of coating and white ink applied can be reduced. Considering these facts comprehensively, the optimal amount of Ni deposition is 20-2000 mg / m ² , preferably 100-2000 mg / m ^2.
Is preferred. As a method for adhering Ni to the steel sheet, a known electroplating or electroless plating method can be applied.

Next, the chemical conversion coating will be described. The steel sheet of the present invention has a chemical conversion coating mainly composed of an organic resin as an upper layer of Ni plating. The chemical conversion coating mainly composed of an organic resin is polymerized during drying, and uniformly covers the Ni plating surface. Therefore, first, it is necessary to strengthen the adhesion with the polyester resin coating laminated on the Ni plating surface. it can. Secondly, since the reduction reaction of oxygen, which is a driving force for the filamentous corrosion, can be suppressed, excellent performance such as prevention of filamentous corrosion is exhibited. Further, since the chemical conversion coating layer mainly composed of an organic resin has particularly good adhesion to a polyester resin film, even if it is subjected to a high degree of drawing-ironing, film peeling caused by insufficient adhesion ( A good can body can be obtained without the occurrence of a broken body caused by severe delamination.

[0015] The amount of the chemical conversion film deposited is, for example, TOTAL ORGANIC manufactured by Shimadzu Corporation as C amount.
CARBON ANALYZER TOC-5000
And is 1 to 100 mg / m ² . If it is less than the lower limit of 1 mg / m ² , the coatability will be poor, and both the anticorrosive action and the adhesion will be insufficient. Further, even in the case of 50% which is the minimum value of the reduction rate of the thickness of the can of the present invention, the resin film is locally peeled after the molding, so-called delamination occurs, or the can body after the molding has a thread-like shape from the opening. Corrosion occurs and is not preferred. However, by applying a chemical conversion coating mainly composed of an organic resin at a C content of 1 mg / m ² or more, the adhesion is improved, and sufficient adhesion is secured at 5 mg / m ² or more.

On the other hand, if it exceeds the upper limit of 100 mg / m ² , no thread-like corrosion occurs, but the chemical conversion coating itself coagulates in the forming process of 70% which is the maximum value of the reduction rate of the thickness of the can of the present invention. In some cases, peeling of the film which is considered to be caused by destruction occurs, which is not preferable. By setting the amount of the chemical conversion coating mainly composed of an organic resin to 100 mg / m ² or less in terms of the amount of C, it is possible to prevent a decrease in adhesion during molding. Therefore, the amount of chemical conversion coating mainly composed of organic resin is C
Although the amount is in the range of 1 to 100 mg / m ² , considering the stability as an industrial product, the C amount is 5 to 50 mg / m ^2.
The range of mg / m ² is preferred and optimal.

Examples of the method for treating a steel sheet include phosphoric acid compounds such as phosphoric acid and salts thereof, condensed phosphoric acid and salts thereof, zirconium phosphate and titanium phosphate, and vinyl ethoxysilane and aminopropyltriethoxy. An aqueous solution mainly composed of an organic silicon compound such as a silane coupling agent such as silane and a water-soluble organic resin such as a water-soluble phenol resin and a water-soluble acrylic resin is spray-coated with the treatment liquid onto a Ni-plated steel sheet. A method of adjusting the amount of adhesion with a squeezing roll, followed by drying and curing, a method of immersing a Ni-plated steel sheet in a treatment liquid, adjusting the amount of adhesion with a squeezing roll, and then drying and curing can be appropriately applied. As the drying and curing method, methods such as drying with hot air and drying in an electric furnace can be applied. The temperature is 150 to 250 ° C., and the drying time is 1 hour.
It is about 0 seconds to 2 minutes.

Next, the polyester resin film on the inner surface of the can applied to the present invention will be described. In the present invention, a thermoplastic polyester resin film is used as the polyester resin film. In the present invention, the reason why the resin film to be coated is limited to the thermoplastic polyester resin film is that heat resistance is good, and the flavor of the contents is secured for the inner surface of the can, for example, a polyolefin such as polyethylene or polypropylene. This is because it has characteristics suitable for can use, which are not present in the base resin film.

As the polyester resin to be coated, terephthalic acid, isophthalic acid, adipic acid,
A polyester resin comprising an acid component such as sebacic acid and an alcohol component such as ethylene glycol and butylene glycol, for example, polyethylene terephthalate (PE
T), homopolymers such as polybutylene terephthalate (PBT) and polyethylene isophthalate (PEI), for example, copolymers which are copolymer resins of ethylene terephthalate and ethylene isophthalate, and blends and homopolymers of such homopolymers Blend resins such as a blend of a polymer and a copolymer, and a blend of copolymers are applied. The melting point (Tm) and the heat of cold crystallization (Hc) of the resin film can be obtained by appropriately selecting the acid component and the alcohol component, the degree of the copolymer, the selection of the blend resin, and the blend ratio thereof.

In the present invention, at least the inner surface of the can comprises a polyester resin film (A) coated from the steel plate side so as to be in contact with the steel plate and a polyester resin film (B) on the polyester resin film, and the polyester resin film (A) has a thickness of 10%. ４５45 μm, melting point (ATm) 215-245
C, the heat of cold crystallization (Hc) is preferably 8.5 to 35.0 J / g, and the polyester resin film (B) has a thickness of 5 to 20 J / g.
The melting point (BTm) is 235 to 260 ° C, the total thickness of the resin film is 15 to 50 µm, and the average density of the polyester resin film (A) and the polyester resin film (B) is less than 1.36. A two-layer polyester resin film is applied.

The reason for forming the two-layer film of the present invention will be described. As described above, the disadvantages of the seamless laminate can include: when the degree of processing (or the degree of deformation) of the thermoplastic resin film-coated metal plate is large; when the resin film on the inner surface of the can is damaged during molding; Since quality cannot be assured, it is necessary to strictly inspect the quality of the can body, and the product yield is inferior to the current painted can. Particularly, in the case of a laminated seamless can using a steel material, the above tendency is large. Such film defects of the resin film on the inner surface side of the laminated can enter into the can forming process, and it is needless to say that minimizing such defects is an important technical problem from the viewpoint of quality and product yield.

Researches by the inventors and others have clarified that the defects of the resin film which occur during the forming process are particularly likely to occur during the ironing process, and it is considered that the causes are roughly summarized in the following two points. . That is, the processing heat of the metal is generated during the forming process, and the characteristics of the resin film are largely changed.
(1) Softening of the resin film, (2) crystallization of the resin film, and the like. The softening of the resin film of (1) causes the resin film to adhere to the punch during ironing, making it difficult for the punch to come off, so-called poor releasability, and causing damage to the resin film on the inner surface side.

When the mold release property is severe, the vicinity of the opening of the can body may buckle, and a situation may occur in which a proper can body height cannot be obtained. In the crystallization of the resin film of (2), the resin film is oriented and crystallized due to the heat generated during the ironing process and the stretching process. As a result, the resin film cannot withstand high processing and causes cracks in the resin film. In any case, it is not preferable because it leads to the occurrence of defects in the film on the inner and outer surfaces of the can.

The two causes of the defects that occur during the ironing process are basically reciprocal in view of the thermal characteristics of the polyester resin film, and it is difficult to achieve the same with a single resin. For this purpose, it is necessary to strictly control the mold shape, the molding temperature, and the like, resulting in a large capital investment and a high manufacturing cost.
Thus, the present invention succeeded in making the two layers of the laminate film covering the steel sheet as in the present invention, and succeeding in avoiding the above-mentioned defect causes in each resin film.

Therefore, in the present invention, the polyester resin film (A) / the polyester resin film (B) is coated from the steel plate side, and the melting point of the coated polyester resin film is always the melting point of the polyester resin film (A). (ATm) is lower than the melting point (BTm) of the polyester resin film (B), and the relationship of ATm <BTm is satisfied. First, the upper polyester resin film (B) of the polyester resin film (A)
It is a resin film having a melting point (BTm) of 235 to 260 ° C. The polyester resin film (B) is as described in (1) above.
To prevent damage to the resin film on the inner surface due to poor releasability due to softening of the resin film, and to prevent the case where the opening of the can body buckles due to severe releasability and cannot obtain the proper can body height. It plays a role. Therefore, the higher the melting point (BTm) of the polyester resin film (B) is, the better the temperature is 235 to 260 ° C.

The melting point (BTm) of the resin film (B) is 2
When the temperature is lower than 35 ° C., the releasability is poor, and the inner film is damaged, leading to a decrease in the corrosion resistance. On the other hand, if the upper limit exceeds 260 ° C., no further effect of the releasability due to the increase in the melting point can be expected, and the effect is saturated. The melting point (BTm) of the polyester resin film (B) on the inner surface of the can is limited by the above-mentioned releasability, but the calorific value during ironing also has a relationship with the degree of processing described later. The moldability alone cannot determine the quality of the releasability, but it is basically advantageous that the melting point is higher, preferably 240 to 255 ° C, more preferably 245 to 255 ° C.

The thickness of the polyester resin film (B) is 5 to 20 μm. Polyester resin film (B)
Has a role in ensuring the releasability as described above, and it has been found that at least 5 μm is required in the studies by the inventors. 5μ
If it is less than m, particularly in the case of a high degree of processing, when a defect occurs due to crystallization of the polyester resin film (B), a phenomenon that the punch surface bites into the polyester resin film (A) and the releasability is inferior is observed. Not preferred.

On the other hand, when the thickness of the polyester resin film (B) is more than 20 μm, the releasability was good even at a high degree of processing, but the defects due to the crystallization of the polyester resin film (B) were poor. )
A phenomenon that the corrosion resistance of the can body is inferior may be observed, which is not preferable. When the rate of reduction in sheet thickness, which is the degree of processing according to the present invention, is in the range of 50 to 70%, the thickness of the polyester resin film (B) is optimally in the range of 5 to 20 μm.

The polyester resin film (A) in contact with the steel sheet plays the role of (2) suppressing the occurrence of defects due to crystallization of the resin film, and for that purpose, a polyester resin having low crystallinity is preferable. The heat of cooling crystallization (Hc) is an index indicating the crystallinity of the resin film, and indicates that the larger the heat amount, the higher the crystallinity of the resin film. In this sense, the polyester resin film has a cold crystallization heat (Hc) in the range of 8.5 to 35.0 J / g. In the case of a crystalline resin film, as described above, the heat generation during the ironing process and the stretching process cause the resin film to be oriented and crystallized. As a result, the resin film cannot withstand a high degree of processing and causes cracks.

In this sense, the present invention provides a heat of cold crystallization (H
If the cold crystallization heat (Hc) is less than 8.5 J / g, orientation crystallization is less likely to occur during molding, and crack-like defects are less likely to occur in the resin film, which is advantageous. However, on the contrary, such a resin is generally soft, and even if the polyester resin film (B) is laminated on the resin, it is not preferable because it causes poor releasability.

On the other hand, the heat of cold crystallization (Hc) is 35.0 J /
If it exceeds g, there is a relationship with the degree of processing, but the crystallinity is too high, and cracking of the resin film may occur during molding, which is not preferable. In particular, in high-forming processing,
There is a high risk of cracking defects. In the molding process, the degree of orientation crystallization of the resin film mainly at the time of the ironing process is also related to the molding process conditions described later, but basically depends largely on the crystallinity inherent to the resin. When the thickness reduction rate, which is the degree of processing, is in the range of 50 to 70%,
If the polyester resin film has a heat of cold crystallization (Hc) in the range of 8.5 to 35.0 J / g, a good can body can be obtained without generating crack-like defects in the resin film.

The melting point (ATm) of the polyester resin film (A) is 215 to 245 ° C. As described above, a chemical conversion coating containing an organic resin having good adhesion exists on the steel sheet surface in contact with the polyester resin film (A). It is necessary to have a low melting point (Tm) for ensuring adhesion. However, when the melting point (ATm) of the polyester resin film (A) is less than 215 ° C., the polyester resin film (A) is strongly softened by the processing heat during ironing, and the releasability of the punch may be inferior. .

When the melting point (ATm) of the polyester resin film (A) is higher than 245 ° C., the crystallinity becomes high. Therefore, at a high working degree, a defect caused by the crystallization of the polyester resin film (B) triggers the polyester resin film (B). Cracks may be generated up to the film (A), resulting in a large defect, which is not preferable because it causes a problem in corrosion resistance. Melting point of polyester resin film (A) (AT
m) is a sheet thickness reduction rate of 50 to 70, which is the degree of working of the present invention.
In the range of%, 220 to 240 ° C is suitable.

The thickness of the polyester resin film (A) is 10 to 45 μm. Basically, the thickness of the polyester resin film (A) is preferably thicker from the viewpoint of the soundness of the resin film after molding, but as described above, the heat of the polyester resin film (A) is increased by the processing heat during ironing. The release properties of the punch due to softening may be poor,
This phenomenon is more likely to occur as the degree of ironing becomes higher and the polyester resin film (A) becomes thicker.
Therefore, the thickness of the polyester resin film (A) is 45
If it exceeds μm, a phenomenon that the releasability of the punch is inferior is observed, which is not preferable.

On the other hand, if the thickness is less than 10 μm, the releasability of the punch is good, but if the degree of processing is high, a defect due to crystallization of the polyester resin film (B) triggers a crack to the polyester resin film (A). Moreover, the thickness of the polyester resin film (A) is too small, and the risk of reaching the steel sheet base is large, which is not preferable.
Regarding the thickness of the resin film, in the present invention, the total thickness of the polyester resin film is 15 to 50 μm.

The thickness of the film laminated on the steel plate surface corresponding to the inner surface of the can is limited in view of the corrosion resistance of the inner surface of the can. If it is less than 15 μm, it depends on the contents to be filled after the can is formed. It may be difficult to ensure good corrosion resistance. On the other hand, if the thickness exceeds 50 μm, the corrosion resistance of the contents is almost sufficiently secured, but the quality becomes substantially excessive, which is not economical. As film thickness, 18-40
μm is a preferable range in terms of quality and economy. An important factor in the selection of the film thickness when performing the method of the present invention is that there is a relationship with the degree of work for reducing the wall thickness of the can wall described later.

That is, when the degree of processing is high, the thickness of the film is naturally reduced according to the degree of processing, and as a result, the anticorrosion performance of the inner surface of the can is reduced. Therefore, when the degree of processing is high, it is desirable to apply a thick film in advance. On the other hand, when the degree of processing is low, a thin film can be applied in advance. The ratio of the film thickness of the polyester resin film (A) to the film thickness of the polyester resin film (B) is as follows: polyester resin film (A): polyester resin film (B) = 1: 1 to 1
9: 1 is preferable, and it is desirable to avoid that the film thickness of the polyester resin film (B) is larger than the film thickness of the polyester resin film (A).

The density of the polyester resin film used in the present invention is an average density of the polyester resin film (A) and the polyester resin film (B), that is, less than 1.36 as a two-layer film. The density is an index indicating the crystalline state of the resin. For example, when the crystallinity of a stretched resin film or the like is high, the density increases. The fact that the density is less than 1.36 g / cm ³ indicates that the crystalline state of the polyester resin film is substantially amorphous.

First, the reason why the resin film coated on the laminate plate is made amorphous is that the workability of the resin film is sufficiently ensured in the subsequent drawing of the cup, redrawing of the cup, and further ironing. If the density exceeds 1.36 g / cm ³ , even if the polyester resin film has low crystallinity, the film may not be able to withstand the molding process and crack defects may occur in the film, which is not preferable. In particular, when the degree of processing is large, the resin film is further oriented and crystallized by the elongation together with the heat generated during the ironing, and as a result, it becomes difficult to follow the processing, and the above-mentioned behavior appears remarkably. Often, the body's corrosion resistance cannot be sufficiently ensured. Therefore,
Forming from a crystallized state with a high density is extremely difficult and unsuitable, especially for a high degree of processing.

Furthermore, in the present invention, after the cup is drawn, the cup is drawn again, and the can is formed by ironing, the obtained can is heated and cooled to reduce the density of the resin film to 1. After reducing the weight to less than 36 g / cm ³ , neck processing and flange processing are performed. The can body obtained through drawing of the cup, redrawing of the cup, and further ironing, due to the processing at this time, the adhesion of the resin film has been significantly reduced, and in this state neck processing and flange processing When performed, the resin film is easily peeled. Therefore, in the present invention, the can body is heated and cooled, and the density of the resin film is again increased to 1.
When it is less than 36 g / cm ³ , it is used for neck processing and flange processing. 1. Increase the density of the resin film.
By setting it to less than 36 g / cm ³ , the resin film can be subjected to neck processing and flange processing with a large diameter without occurrence of peeling or cracking.

In particular, in order to cope with a high neck processing rate and a reduction in diameter, a higher processing adhesion of the resin film is further required. In this case, the lower the density of the resin film, the higher the degree of amorphization. Therefore, it becomes good. 1.36 g / c density
The reason for limiting to less than m ³ is from the above-mentioned reason. In particular, the state before drawing, necking and flange processing in the first step is preferably less than 1.35 g / cm ³ . As for the film on the outer surface side of the can, the polyester resin film used for the inner surface side of the can in the present invention may be applied.However, titanium oxide is inferior in printing appearance because of the blackness peculiar to steel in terms of appearance. Applying a polyester resin film containing a white pigment such as,
It is desirable from the viewpoint of securing the printed appearance. In this case, a film containing 10 to 20% by weight of a titanium oxide pigment having an average particle diameter of 0.1 to 3.0 μm is used.

As a method for producing a laminated steel sheet coated with a polyester resin film, a resin film is supplied to the surface of a heated steel sheet, coated by thermocompression bonding between rolls, immediately quenched, and immediately cooled to an amorphous state. Method, extruding the molten resin, supplying it to the steel sheet and coating it, immediately quenching, and the method of making amorphous, for example, when applying a biaxially stretched film, once coated polyester resin, If necessary, a method of further heating to a temperature higher than the melting point of the resin and then immediately quenching to make it amorphous can be applied. As a method for heating the steel sheet, a heating method such as a method of heating in an electric furnace, a method of heating with hot air, a method of heating by contacting with a heating roll, and a method of induction heating at a high frequency can be adopted.

Next, the degree of processing of the can body of the present invention, that is, the reduction rate of the thickness of the can wall portion will be described. The degree of processing of the can body of the present invention is 5 as a value obtained from the following equation (1).
0 to 70%. Working ratio (%) = {(Tb−Tw) / Tb} × 100 (1) Tb: thickness of steel plate at bottom of can Tw: thickness of thinnest portion of steel plate at can wall It is in the category of DI cans currently manufactured from steel and aluminum materials and is not special, but if the working degree is less than 50%, there is no damage due to processing of the coated polyester resin film on the inner and outer surfaces, Although a good can body can be obtained, in particular, when the original steel plate thickness (corresponding to the thickness of the steel plate at the bottom of the can) is large, the can weight becomes heavy and is not economical.

On the other hand, when the degree of processing exceeds 70%, the releasability of the polyester resin film and the punch is poor on the inner surface, and it is often easy to secure corrosion resistance due to damage of the resin film. In addition, the polyester resin film on the outer surface also tends to be "galled", which is not preferable. Furthermore, in particular, when the base plate thickness of the steel plate (corresponding to the steel plate thickness at the bottom of the can) is thin, wrinkles are formed by neck processing described later, or the opening of the can body is broken by flange processing, so-called flange cracking occurs. Is not preferred. The limitation of the degree of processing is due to the above-mentioned reason, and 50 to 70% is optimal.

Next, the method for forming a can according to the present invention will be described. The can body of the present invention comprises a first step of forming a laminated steel sheet coated with a polyester resin film into a cup shape by drawing, and then further redrawing the cup obtained in the first step. The second step of forming a cup having a smaller can diameter and a higher can height than the cup obtained in the above step, and then passing the can wall of this cup between a punch and a ironing die to so-called ironing to thin the can wall thinly The third step to be performed, the fourth step to form the dome of the bottom of the can, and then the trimming for cutting the can body obtained in the fourth step to a regular can height, and then reducing the diameter of the can opening. The fifth step is to perform neck processing and flange processing necessary for tightening the canopy.

In the above-mentioned forming method, the drawing in the first step, the redrawing in the second step, and the ironing in the third step are all processings involving an increase or decrease in the thickness of the can wall. The dome forming of the can bottom in the fourth step and the necking / flanging in the fifth step are processings that do not substantially increase or decrease the plate thickness. Therefore, in the case of the seamless can, the can after the third step is the final can.
The processing method for obtaining the can of the present invention is not particularly different from the processing method for DI cans currently manufactured from steel materials and aluminum materials. However, in order to sufficiently ensure the performance of the can of the present invention. It is desirable to adopt the following means.

That is, in the drawing in the first step and the redrawing in the second step, the temperature of the laminated steel plate or cup or the temperature of the mold is changed to the glass transition temperature (T
It is preferable that the heat treatment be performed in the range from g) to the cold crystallization temperature (Tc) in order to ensure the soundness of the resin film at the bottom corner of the cup. Furthermore, in the drawing process in the first step and the redrawing process in the second step, in order to reduce the load of the coated resin film in the ironing process performed in the third step, a stretching process and a mild ironing process are added. It is desirable to draw or redraw.

In the ironing in the third step, the temperature of the cup obtained in the redrawing in the second step is set to 50 ° C. or less, and then the temperature of the working mold is set to 100 ° C. or less, preferably coated on the inner surface of the can. It is preferable to carry out the process while maintaining the temperature below the glass transition temperature (Tg) of the resin film in order to suppress the occurrence of defects due to crystallization of the resin film and to have good releasability from the punch. The ironing can be performed by one-step ironing with one ironing die or multi-step ironing with two or three ironing dies. However, considering the heat accumulation during processing, the number of ironing dies is smaller. One-step ironing, in which ironing dies are performed on one sheet, is preferable.

[0049]

EXAMPLES Hereinafter, the effects of the method of the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. The evaluation method used in this example is as follows. (1) The density of the resin film was measured by a density gradient tube method. (2) The heat of cold crystallization (Hc) and the melting point (T
m) is measured by a differential scanning calorimeter (DSC) at a heating rate of 10 ° C./min, and the area of the cold crystallization heat (Tc) peak is calculated as the cold crystallization heat, and the melting point (Tm) is calculated as the peak temperature. Melting point. (3) Intrinsic viscosity (IV) of the resin film was determined by an Ubbelohde viscometer with a weight ratio of phenol to tetrachloroethane of 6:
0.100 ± 0.003 g of the resin film was dissolved in the solution of No. 4 and measured at 30.0 ± 0.1 ° C.

(4) Microcracks at the bottom corners of the can after drawing of the cup were observed with an optical microscope to evaluate the degree. The evaluation was performed by setting evaluation criteria as follows. ：: good without cracks □: slight cracks generated △: clear cracks generated ×: severe cracks generated

(5) The releasability of the film and the processing punch is as follows:
The degree of buckling of the can body that occurred at the top of the molded can was observed and evaluated.
The releasability was evaluated by setting evaluation criteria as follows. ○: good without buckling of can opening □: slight buckling of can opening △: buckling about 1/3 of opening circumference ×: buckling of 1/3 or more of opening circumference

(6) Regarding the state of the resin film in the neck processing and the flange processing, the peeling state and the crack generation state were evaluated by observing with a naked eye or an optical microscope. The evaluation of the peeling state and the crack generation state was performed by setting evaluation criteria as follows. ：: good without peeling or cracking □: slight peeling or fine cracking △: partial peeling or cracking ×: peeling (7) Regarding the degree of damage to the resin film on the inner surface of the can,
Using an electrolytic solution obtained by adding 0.1% of a surfactant to 1.0% saline solution, using a can as an anode and a cathode as a copper wire, measure a current value after 3 seconds at an applied voltage of 6 V, and measure the current value of the resin film. The soundness was evaluated. (Hereafter, this evaluation method is referred to as QTV test)

(8) Regarding the evaluation of dent resistance, 35
After filling a 0 ml can with water and performing retort treatment at 125 ° C. for 30 minutes, cool at 5 ° C. for 1 day, drop the can bottom down at an angle of 60 ° from a height of 80 cm, and open and dry the can. Then, the portion other than the impact deformed portion is sealed with an insulating paint, and the degree of occurrence of defects in the resin film at the impact deformed portion is measured with an electrolytic solution used for a QTV test.
The current value after 3 seconds was measured for evaluation of the soundness of the film of the resin film. (Hereafter, the dent resistance shows the evaluation result by this method)

(9) Thread Corrosion For the evaluation of the thread corrosion, a salt spray test (JIS-Z-2371) was performed for 1 hour after a cross cut reaching the base steel plate was cut into the can body of the can body with a cutter. After 30
Exposure was performed for 2 weeks in an environment of 85 ° C. and 85% RH, and the occurrence of filamentous corrosion was observed and evaluated. ：: Good without filiform corrosion □: Slightly filiform corrosion generated △: Medium degree of filiform corrosion ×: Large occurrence of filiform corrosion

(Example 1) On both sides of a steel plate having a thickness of 0.21 mm, the amount of Ni deposited on one side was 10 mg / m ² (No.
1), 35 mg / m ² (No. 2), 235 mg / m ²
(No. 3), 420 mg / m ² (No. 4), 780
^{mg / m 2 (No.5),} 1670mg / m 2 (No.
6) After preparing the Ni-plated steel sheet by an electroplating method in a Watt bath, a chemical conversion treatment solution containing a phenolic resin and condensed phosphoric acid is applied and dried, and the amount of C attached to one surface is 10 mg.
/ M ² . No. 1 to No. The Ni-plated steel sheet No. 6 was subjected to a chemical conversion treatment to prepare a surface-treated steel sheet.

Next, the above No. 1 to No. Heat the surface-treated steel sheet of No. 6 with a jacket troll, and the sheet temperature is 250 ° C.
A polyester resin film (A) having a thickness of 15 μm and a melting point of 232 ° C., a heat of cold crystallization of 23.4 J / g and a thickness of 10 μm and a melting point of 247 ° C. on the steel plate surface corresponding to the inner surface of the can
After coating the two-layer film composed of the polyester resin film (B) so that the polyester resin film (A) is in contact with the steel sheet, the steel sheet is further heated to 260 ° C. and immediately quenched, and then rapidly amorphized polyester resin film laminated steel sheet It was created. In addition, on the steel plate surface corresponding to the outer surface of the can,
A polyester resin film having a melting point of 248 ° C. and a titanium oxide content of 10% by weight was coated. The laminated steel sheet thus obtained was lubricated with a forming lubricant and then heated to a sheet temperature of 75 ° C.
Draw processing with stretch processing added.

The cup obtained at this time was examined for the occurrence of microcracks in the resin film at the corner of the bottom of the can. Next, the temperature of the cup obtained by drawing was set to 75 ° C., and redrawing with ironing was performed. After that, the die temperature was maintained at 40 ° C., and ironing was performed with a final processing degree of 67%. A can-sized two-piece can was made. With respect to the can thus obtained, the mold releasability of the resin film was examined. In addition, the above can body is regular 350ml
The opening was trimmed to the size of a beer can, quenched immediately after heating to 260 ° C. to make the polyester resin film amorphous, and then necked and flanged 204. With respect to the regular can thus obtained, the dent resistance, the film peeling state of the neck / flanged portion, the thread-like corrosion of the can, and the inner surface quality of the can were examined.

Table 1 shows the contents of the laminated steel sheet used in Example 1 and the evaluation results. As can be seen from Table 1, Examples 1 to 5 (No. 2 to No. 5) of the present invention have little or no occurrence of thread-like corrosion, have good adhesion of the inner and outer films, and have neck processing and flanges. Almost no film peeling during processing. Furthermore, the dent resistance and other performances of the inner film are also good, and a good performance is shown in a well-balanced manner. In contrast, Comparative Example 1 (No.
1) is inferior to the examples of the present invention, such as the occurrence of thread-like corrosion, film peeling during neck processing and flange processing of the inner and outer films, and dent resistance.

[0059]

[Table 1]

(Example 2) On both sides of a steel plate having a thickness of 0.21 mm, Ni of 530 mg / m ²
After making a plated steel sheet by electroplating in a watt bath,
A chemical conversion treatment solution containing a phenol resin and aminopropyltriethoxysilane was applied and dried, and the amount of C adhered to one side was 0.3 mg / m ² (No. 7) and 2 mg / m ² (N
o. 8), 8 mg / m ² (No. 9), 38 mg / m ²
(No. 10), 87 mg / m ² (No. 11), 12
A surface-treated steel sheet of 0 mg / m ² (No. 12) was prepared. Then, the above No. 8 to No. Thirteenth surface-treated steel sheet was coated with a polyester resin film used in Example 1 under the same conditions as in Example 1 to produce a laminated steel sheet. The steel sheet surface corresponding to the outer surface of the can has a melting point of 2
At 48 ° C., a polyester resin film having a titanium oxide content of 10% by weight was coated. The laminated steel sheet thus obtained was coated with a forming lubricant, heated, and then subjected to drawing at a sheet temperature of 75 ° C. with stretching.

The cup obtained at this time was examined for the occurrence of microcracks in the resin film at the corner of the bottom of the can. Next, the temperature of the obtained cup was set to 75 ° C., and redrawing with ironing was performed. Thereafter, the die temperature was maintained at 40 ° C., and ironing was performed with a final working degree of 68%.
A can of the size of a ml beer can was prepared. With respect to the can thus obtained, the mold releasability of the resin film was examined. Furthermore,
The opening of the can was trimmed to a regular 350 ml beer can size, immediately heated to 260 ° C. and immediately cooled to make the polyester resin film amorphous, and then necking and flange processing of 204 were performed. With respect to the regular can thus obtained, the dent resistance, the film peeling state of the neck / flanged portion, the thread-like corrosion of the can, and the inner surface quality of the can were examined.

Table 2 shows the contents of the laminated steel sheet used in Example 2 and the evaluation results. From Table 2, 6 to 9 (No. 8 to No. 11) of the examples of the present invention are satisfactory without any occurrence of thread-like corrosion. In addition, the adhesiveness between the inner and outer films is good, and film peeling during neck processing and flange processing is scarcely observed. Further, it can be seen that the film has good properties and well-balanced good performance. On the other hand, in Comparative Example 2 (No. 7), thread-like corrosion occurred, and in Comparative Example 3 (No. 12), the film was peeled off in the neck processing and the flange processing of the inner and outer films. It turns out that it is inferior to an example.

[0063]

[Table 2]

(Example 3) On both sides of a steel plate having a thickness of 0.21 mm, Ni of 455 mg / m ²
After making a plated steel sheet by electroplating in a watt bath,
Apply chemical conversion solution containing phenolic resin and phosphoric acid
After drying, a surface-treated steel sheet having a C adhesion amount on one side of 12 mg / m ² was prepared. Next, the surface-treated steel sheet was heated with a jacket roll to 245 ° C. on both sides of the steel sheet.
The polyester resin film (A) having a melting point of 232 ° C. and a heat of cold crystallization of 23.4 J / g was 5 μm thick (No. 1).
3), thickness 10 μm (No. 14), thickness 20 μm
(No. 15), thickness 30 μm (No. 16), thickness 40 μm (No. 17), thickness 50 μm (No. 1)
8) A two-layer film composed of each film and a polyester resin film (B) having a thickness of 10 µm and a melting point of 247 ° C is coated so that the polyester resin film (A) is in contact with the steel sheet. Immediately after heating to 265 ° C., the mixture was rapidly cooled to produce an amorphous polyester resin film-laminated steel sheet. The laminated steel sheet thus obtained was coated with a forming lubricant, heated, and then subjected to drawing at a sheet temperature of 75 ° C. with stretching.

The cup obtained at this time was examined for the occurrence of microcracks in the resin film at the corner of the bottom of the can. Next, the temperature of the cup obtained by drawing was set to 75 ° C., and redrawing with ironing was performed. After that, the die temperature was maintained at 40 ° C., and ironing was performed with a final processing degree of 67%. A can-sized two-piece can was made. With respect to the can thus obtained, the mold releasability of the resin film was examined. In addition, the above can body is regular 350ml
Trim the opening to a beer can size, 260-26
Immediately after heating to 5 ° C., the mixture was rapidly cooled to make the polyester resin film amorphous, and then neck processing and flange processing of 204 were performed. With respect to the regular can thus obtained, the dent resistance, the film peeling state of the neck / flanged portion, the thread-like corrosion of the can, and the inner surface quality of the can were examined.

Table 3 shows the contents of the laminated steel sheet used in Example 3 and the evaluation results. From Table 3, 10 to 13 (No. 14 to No. 17) of the present invention have no film crack at the bottom corner portion of the cup can, and have a neck /
It can be seen that there was no film peeling even in the flange processing, and the film was good. Further, it can be seen that there is no thread-like corrosion, the QTV value of the can body is low, the dent resistance is good, and the can body has good and balanced performance. In contrast, Comparative Example 4
(No. 13) had a film crack at the bottom corner of the cup can, the QTV value of the can was high, and the dent resistance was poor. Further, it can be seen that Comparative Example 5 (No. 18) is inferior to Comparative Example 5 in that the mold release property and the film peeled off during neck processing and flange processing.

[0067]

[Table 3]

(Example 4) On both sides of a steel plate having a thickness of 0.19 mm, Ni of 455 mg / m ²
After making a plated steel sheet by electroplating in a watt bath,
A chemical conversion treatment solution containing a phenolic resin and condensed phosphoric acid was applied and dried to prepare a surface-treated steel sheet having a C adhesion amount on one side of 12 mg / m ² . As the film to be coated, the polyester resin film (A) has a thickness of 20 μm.
m, melting point: 208 ° C., heat of cold crystallization: 8.7 J /
g film (No. 19), melting point 217 ° C., film having a cold crystallization heat of 15.8 J / g (No. 20), melting point 225 ° C., film having a cold crystallization heat of 17.8 J / g (N
o. 21), melting point: 232 ° C., heat of cold crystallization: 22.8 J
/ G film (No. 22), film with a melting point of 243 ° C, heat of cold crystallization of 32.7 J / g (No. 23), film with a melting point of 248 ° C, film of a heat of cold crystallization of 40.0 J / g A two-layer film was prepared by combining each film of (No. 24) and a film having a thickness of 10 μm and a melting point of 252 ° C. as the polyester resin film (B), and heating the surface-treated steel sheet with a jacket roll, . 19 ~
No. After coating the polyester resin film (A) on both sides of the steel sheet at a sheet temperature 10 to 15 ° C. higher than the melting point of each polyester resin film (A) of No. 24,
Further, the steel sheet was immediately cooled after being heated to 265 ° C. to prepare an amorphous polyester resin film-laminated steel sheet. The laminated steel sheet thus obtained was coated with a forming lubricant, heated, and then subjected to drawing at a sheet temperature of 75 ° C. with stretching.

The cup obtained at this time was examined for the occurrence of microcracks in the resin film at the corner of the bottom of the can. Next, the temperature of the cup obtained by drawing was set to 75 ° C., and redrawing with ironing was performed. After that, the die temperature was maintained at 40 ° C., and ironing was performed with a final processing degree of 63%. A can-sized two-piece can was made. With respect to the can thus obtained, the mold releasability of the resin film was examined. In addition, the above can body is regular 350ml
The opening was trimmed to the size of a beer can and immediately cooled after heating to 265 ° C. to make the polyester resin film amorphous, followed by necking and flange processing of 204. With respect to the regular can thus obtained, the dent resistance, the film peeling state of the neck / flanged portion, the thread-like corrosion of the can, and the inner surface quality of the can were examined.

Table 4 shows the contents of the laminated steel sheet used in Example 4 and the evaluation results. Table 4 shows that Examples 14 to 17 (Nos. 20 to 23) of the present invention also have good mold release properties and other properties, and have well-balanced and good performance. . In contrast, Comparative Example 6 (N
o. 19) is inferior in mold release property, and Comparative Example 7 (No.
24) indicates that both the QTV value and the dent resistance of the obtained can were inferior to those of the examples of the present invention.

[0071]

[Table 4]

(Example 5) On both sides of a steel plate having a thickness of 0.17 mm, Ni of 455 mg / m ²
After making a plated steel sheet by electroplating in a watt bath,
A chemical conversion treatment solution containing a phenolic resin and condensed phosphoric acid was applied and dried to prepare a surface-treated steel sheet having a C adhesion amount on one side of 12 mg / m ² . As the film to be coated, the polyester resin film (A) has a thickness of 20 μm.
m, the melting point is 238 ° C., the heat of cold crystallization is the same as 28.5 J / g, and the melting point of the polyester resin film (B) is 25.
A film having the same thickness as 5 ° C. and a thickness of 3 μm (No. 2)
5), a film having a thickness of 6 μm (No. 26), a film having a thickness of 12 μm (No. 27), a film having a thickness of 18 μm (No. 28), and a film having a thickness of 24 μm (No. 29). After preparing a combined two-layer film, the surface-treated steel sheet is heated with a jacket roll, and coated on both sides of the steel sheet so that the polyester resin film (A) is in contact with the steel sheet at a sheet temperature of 255 ° C.
Further, the steel sheet was rapidly cooled immediately after being heated to 265 to 270 ° C. to prepare an amorphous polyester resin film-laminated steel sheet. The lamination steel sheet thus obtained was coated with a forming lubricant, heated, and then subjected to drawing at a sheet temperature of 80 ° C. with stretching.

The cup obtained at this time was examined for the occurrence of microcracks in the resin film at the corner of the bottom of the can. Next, the temperature of the cup obtained by drawing was set to 80 ° C., and redrawing with ironing was performed. After that, the die temperature was maintained at 40 ° C., and ironing was performed with a final working degree of 56%. A can-sized two-piece can was made. With respect to the can thus obtained, the mold releasability of the resin film was examined. In addition, the above can body is regular 350ml
The opening was trimmed to the size of a beer can, quenched immediately after heating to 260 ° C. to make the polyester resin film amorphous, and then necked and flanged 204. With respect to the regular can thus obtained, the dent resistance, the film peeling state of the neck / flanged portion, the thread-like corrosion of the can, and the inner surface quality of the can were examined.

Table 5 shows the contents of the laminated steel sheet used in Example 5 and the evaluation results. From Table 5, it can be seen that Examples 20 to 20 (Nos. 26 to 28) of the present invention also have good mold release properties and other characteristics, and have well-balanced and good performance. . In contrast, Comparative Example 8 (N
o. 25) shows the mold release property and the QTV value and the dent resistance of the obtained can body, and Comparative Example 9 (No. 29) shows that the obtained can body has both the QTV value and the dent resistance of the present invention. It turns out that it is inferior to.

[0075]

[Table 5]

(Example 6) On both sides of a 0.17 mm thick steel plate, 455 mg / m ² Ni
After making a plated steel sheet by electroplating in a watt bath,
A chemical conversion treatment solution containing a phenolic resin and condensed phosphoric acid was applied and dried to prepare a surface-treated steel sheet having a C adhesion amount on one side of 12 mg / m ² . As the film to be coated, the polyester resin film (A) has a thickness of 20 μm.
m, the melting point is 225 ° C., the heat of cold crystallization is the same as 17.8 J / g, and the polyester resin film (B) has a thickness of 10
μm and a melting point of 232 ° C. (No. 3)
0), a film having a melting point of 238 ° C. (No. 31), a film having a melting point of 248 ° C. (No. 32), and a melting point of 252 ° C.
A film (No. 33) and a film (No. 34) having a melting point of 260 ° C. were prepared in combination with each other to prepare a two-layer film, and the surface-treated steel sheet was heated with a Jacketrol to reach 240 ° C. After the resin film (A) is coated on both sides of the steel sheet so as to be in contact with the steel sheet, the steel sheet is further heated to a temperature 15 ° C. higher than the melting point of each film of the polyester resin film (B), immediately quenched, and amorphized. A polyester resin film laminated steel sheet was prepared. The laminated steel sheet thus obtained was coated with a forming lubricant, heated, and then subjected to drawing at a sheet temperature of 75 ° C. with stretching.

The cup obtained at this time was examined for the occurrence of microcracks in the resin film at the corner of the bottom of the can. Next, the temperature of the cup obtained by drawing was set to 75 ° C., and redrawing with ironing was performed. After that, the die temperature was maintained at 40 ° C., and ironing was performed with a final processing degree of 56%. A can-sized two-piece can was made. With respect to the can thus obtained, the mold releasability of the resin film was examined. In addition, the above can body is regular 350ml
The opening is trimmed to the size of a beer can, heated to a temperature 15 ° C. higher than the melting point of each of the polyester resin films (B), immediately quenched, and the polyester resin film is made amorphous. Processing was performed. In addition, the above-mentioned No. Regular 3 from 32
Even in a state where the polyester resin film of the can body obtained by trimming the opening to the size of a 50-ml beer can was not made amorphous, neck processing and flange processing of 204 were performed (No. 35).

Table 6 shows the contents of the laminated steel sheet used in Example 6 and the evaluation results. From Table 6, it can be seen that 21 to 24 (Nos. 31 to 33) of the examples of the present invention also have good mold release properties and other characteristics, and have well-balanced good performance. . In contrast, Comparative Example 10 (N
o. 30) is the mold release property, and Comparative Example 11 (No. 3)
In the case of 5), it can be seen that the comparative example is inferior to the example of the present invention, for example, the film is peeled off in the neck processing and the flange processing.

[0079]

[Table 6]

[0080]

As described above, since the polyester resin film on the inner surface of the can obtained by carrying out the present invention has excellent film soundness, a highly corrosion-resistant film-laminated two-piece can is obtained. Is obtained. Therefore, various contents can be filled, and since it is possible to safely cope with the unification of varieties, it is economically advantageous and has great social significance.

Continued on the front page (72) Inventor Hideki Utsunomiya 5-5-1 Nishihashimoto, Sagamihara City, Kanagawa Prefecture Inside the Daiwa Seikan Co., Ltd. (72) Inventor Kazuhiro Tsujimoto 5-5-1 Nishihashimoto, Sagamihara City, Kanagawa Prefecture Inside the Technology Development Center, Daiwa Seikan Co., Ltd. (72) Inventor Hirokazu Yokoya 1-1, Hibata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka New Nippon Steel Corporation Inside Yawata Works (72) Inventor Shigeru Hirano No. 1-1 Tobata-cho, Tobata-ku New Nippon Steel Corporation Yawata Works F-term (reference) 3E033 AA06 BA08 BA17 BB08 CA14 EA12 4F100 AA21 AA21H AB03A AB16B AK01C AK33 AK41D AK41E AK42 BA05 BA06 BA07 BA10C BA10E BAH EJ50 EJ68C GB16 GB23 JA04D JA04E JA11D JA12D JA12E JA13D JA13E JA20A JA20D JA20E JB02 JK14 JL01 JL02 YY00A YY00B YY00C YY00D YY00E 4K044 AA02 AB02 BA06 BA17 BB02 BC16 CA15 CA16

Claims (3)

[Claims] 1. A seamless can obtained by drawing and ironing a film-laminated metal sheet, wherein both sides of the steel sheet are
Ni plating of ^{20 to} 2000 mg / m ² as one-side adhesion amount, and 1 to 100 mg / cm ² as one-side adhesion C amount on the upper layer
m ² , a chemical conversion coating layer mainly composed of an organic resin, a polyester resin film on at least the inner layer side of the chemical conversion coating layer, a thickness of 10 to 45 μm and a melting point (ATm) of 215
A polyester resin film (A) having a thickness of 5 to 20 μm and a melting point (BTm) of 235 to 260 ° C. and a melting point (ATm) of the polyester resin film (A). And the melting point (BTm) of the polyester resin film (B) satisfies the relationship of ATm <BTm.
A 50 μm two-layer polyester resin film, wherein the average density of the polyester resin film (A) and the polyester resin film (B) is less than 1.36 g / cm ³ , and the polyester resin film (A) is coated so as to be in contact with the steel sheet. It is drawn and ironed from a laminated steel sheet of a polyester resin film, and the can body after the forming process is further heated and quenched to a temperature higher than the melting point of the polyester resin film, whereby the polyester resin film is made amorphous. And laminated seamless cans. 2. The laminated seamless can according to claim 1, wherein the heat of cold crystallization (Hc) of the polyester resin film (A) is 8.5 to 35.0 J / g. 3. The thickness (T) of the thinnest portion of the steel plate in the can wall portion.
3. The laminate according to claim 1, wherein w) falls within a range of the following expression (1) as a sheet thickness reduction rate (working degree) in relation to a sheet thickness (Tb) of the bottom of the can. Seamless cans. {(Tb−Tw) / Tb} × 100 = 50-70% (1)