JP7154784B2 - Two-piece can manufacturing method and can body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a two-piece can obtained by drawing and ironing a metal plate, and a can body .

A two-piece can formed by drawing and ironing a metal plate is known as a steel can that is a beverage container. Such a two-piece can is used as a container for a canned beverage by molding a bottomed cylindrical can body having a bottom, filling the can body with a beverage, and then winding up a can lid.

The metal plate used in two-piece cans is made of steel-based steel plate with a thermoplastic resin laminated on its surface to prevent corrosion caused by contact with the beverage inside. things are used. In the metal plate, a plated layer of Sn or the like is provided on the surface of the base material in order to provide corrosion resistance, and a resin material is laminated thereon.

In addition, as a method for manufacturing such a two-piece can, the can body is heated for a predetermined period of time at a temperature equal to or higher than the melting temperature of the resin material, and then rapidly cooled before forming the concave-convex bead or bottle rim on the can body. There is also known a technique for improving corrosion resistance by preventing peeling of a resin material laminated to the surface (see, for example, Patent Document 1).

WO2015/037074

In such a two-piece can, during the drawing and ironing process, a large force is applied to the surface of the metal plate that forms the inner surface of the can. For this reason, when the metal plate is drawn and ironed, the Sn plated layer existing in a sea-island pattern on the base material before processing becomes striped. If the Sn plating layer becomes striped, the corrosion resistance of the can body is lowered, which is a problem.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing a two-piece can and a can body capable of improving corrosion resistance.

According to one aspect of the present invention, a method for manufacturing a two-piece can includes a Sn plating layer of 100 mg/m ² or more and 1500 mg/m ² or less provided on a steel base material, and a 6 mg Sn plating layer provided on the Sn plating layer. /m ² or more and 100 mg/m ² or less of a Cr plating layer , a coating layer laminated on the Cr plating layer and composed of a thermoplastic resin , and a Ni plating layer between the base material and the Sn plating layer A punching step of punching a metal plate that has not been heat-treated into a disk shape, and a step of punching the disk-shaped metal plate into a bottomed cylindrical can body so that the coating layer is the inner surface and a forming step of performing drawing and ironing, wherein the forming step is performed when Tw is the plate thickness of the thinnest portion of the cylindrical wall portion of the can body and Tb is the plate thickness of the bottom portion of the can body. , the plate thickness reduction rate from the disk-shaped metal plate to the can body ((Tb-Tw) / Tb) × 100, 35% ≤ ((Tb-Tw) / Tb) × 100 (% )≦60%.

According to one aspect of the present invention, the can body is a can body for a two-piece can, wherein a Sn plating layer of 100 mg/m 2 or more and 1500 mg/m 2 or less provided on a ^{steel base} material, the Sn plating A Cr plating layer of 6 mg/m ^{2 or more and 100 mg/m 2 or} less provided on the layer, a coating layer laminated on the Cr plating layer and composed of a thermoplastic resin , and the base material and the Sn plating layer A plate at the thinnest part of the cylindrical wall, which has a Ni-plated layer provided between and is formed into a bottomed cylindrical shape using a disc-shaped metal plate that has not been heat-treated When the thickness is Tw and the plate thickness of the bottom is Tb, the plate thickness reduction rate from the cylindrical metal plate ((Tb−Tw)/Tb)×100 is 35%≦((Tb− Tw)/Tb)×100(%)≦60%.

ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the manufacturing method and can body of a two-piece can which can improve corrosion resistance.

BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows typically the structure of the two-piece can which concerns on one Embodiment of this invention. FIG. 4 is a cross-sectional view showing a part of the configuration of a metal plate forming the can body of the two-piece can. Sectional drawing which shows a part of structure of the other example of the same metal plate. The flowchart which shows an example of the manufacturing method of the same two-piece can. The flow chart which shows typically an example of the manufacturing method of the same can body. Explanatory drawing which shows the result of the evaluation test of the same can body. Explanatory drawing which shows the result of the evaluation test of the same can body. Explanatory drawing which shows the result of the evaluation test of the same can body. Explanatory drawing which shows the result of the evaluation test of the same can body. Explanatory drawing which shows the result of the evaluation test of the same can body. Explanatory drawing which shows the result of the evaluation test of the same can body.

[One embodiment]
A two-piece can 1 according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG.
FIG. 1 is a cross-sectional view schematically showing the configuration of a two-piece can 1 according to an embodiment of the present invention, and FIG. FIG. 3 is a cross-sectional view showing another example of the metal plate 100 forming the can body 11, showing the inner surface side of the can body 11, and FIG. A flowchart showing an example of the method, FIG. 5 is a flowchart schematically showing an example of the method for manufacturing the can body 11 .

The two-piece can 1 has a can body 11 and a top lid 12 which is wound around the can body 11. - 特許庁The two-piece can 1 is constructed by filling a can body 11 with a content 90 such as a beverage and winding a top lid 12 around the can body 11 .

The can body 11 is configured in a bottomed cylindrical shape having a bottom 21 forming the bottom of the can body 11, a body 22 forming a cylindrical wall, and a neck 23 having a reduced diameter at the upper end of the body 22. The can body 11 has a flange 24 at the upper end of the neck 23 . The can body 11 is formed by forming a disk-shaped metal plate 100 by drawing and ironing.

When the thickness of the thinnest part of the body portion 22 of the can body 11 is Tw, and the thickness of the bottom 21 of the can body 11 is Tb, the can body 11 extends from a disc-shaped metal plate 100 to the can body 11. ((Tb−Tw)/Tb)×100, which is the plate thickness reduction rate when molded,
35%≦((Tb−Tw)/Tb)×100(%)≦60%
is set to

The metal plate 100 includes a base material 101, a Sn plated layer 120 provided on the base material 101, a Cr plated layer 130 provided on the Sn plated layer 120, and a resin material provided on the Cr plated layer 130. and a covering layer 140 composed of 2, the metal plate 100 has a Ni-plated layer 110 between the base material 101 and the Sn-plated layer 120, and is a steel plate that has not been heat-treated, or 1, the steel sheet has no Ni plating layer 110 and is heat-treated. Here, the heat treatment is a process of reflowing Sn.

The base material 101 is composed of a general steel material for can manufacturing. A CL material, for example, is used as the base material 101 used for the metal plate 100 having the Ni plating layer 110 . As the base material 101 used for the metal plate 100 without the Ni plating layer 110, for example, an LTS material is used. Here, the CL material is CANLITE (registered trademark), and the LTS material is LowTinSteel.

The Ni plating layer 110 is provided on at least one main surface of the base material 101, more specifically on the inner surface of the can body 11, and has a basis weight of less than 200 mg/ ^m2 .

Sn plated layer 120 is provided on at least one main surface of base material 101 . In the metal plate 100 provided with the Ni plating layer 110, the Sn plating layer 120 is provided on the Ni plating layer 110, and in the metal plate 100 without the Ni plating layer 110, the Sn plating layer 120 is provided on the base material 101. be done. In the Sn plating layer 120, Sn is uniformly distributed on the base material 101 in a granular form, and the coverage of the main surface of the base material 101 is 44% or more and 63% or less. Also, the Sn plating layer 120 is set to have a basis weight of 100 mg/m ² or more and 1500 mg/m ² or less. A part of the Sn plated layer 120 is alloyed with Fe of the base material 101 to form an Fe—Sn alloy between the base material 101 and the Sn plated layer 120 .

The Cr plated layer 130 is provided on the Sn plated layer 120 provided on at least one main surface of the base material 101 and has a basis weight of 6 mg/m ² or more and 100 mg/m ² or less.

The coating layer 140 is made of a thermoplastic resin material that is amorphized and has excellent dent resistance. Here, the thermoplastic resin material includes, for example, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, ethylene terephthalate/isophthalate copolymer, butylene terephthalate/isophthalate copolymer, polyethylene, polypropylene, ethylene- Propylene copolymers, olefinic resins such as modified olefins, polycarbonates, nylon resins, etc., or mixtures thereof may be used. The melting temperature of the thermoplastic resin material is 200°C to 260°C.

Preferably, the thermoplastic resin material is a polyester resin. The coating layer 140 is formed by laminating a film made of this polyester resin onto the Cr plated layer 130 via an adhesive layer made of an adhesive.

Such a metal plate 100 is composed of a base material 101, a Ni plating layer 110, a Sn plating layer 120 and a Cr plating layer 130, and has an original plate thickness of 0.15 mm to 0.30 mm. The thickness of the coating layer 140 provided on the surface is set to 2 μm to 40 μm, and the thickness of the coating layer provided on the main surface which is the outer surface side of the can body 11 is set to 10 μm to 30 μm. Also, the thickness of the adhesive layer provided on each coating layer is set to 0.5 μm to 5 μm.

The top lid 12 has a panel portion 31 and a flange 32 . The panel portion 31 has tabs secured by rivets and score lines provided adjacent to the tabs. That is, the upper lid 12 is a so-called stay-on-tub lid or a full open-end lid.

Next, an example of a method for manufacturing the two-piece can 1 having such a structure will be described with reference to FIGS. 4 and 5. FIG. Also, in this embodiment, the two-piece can 1 will be described using an example in which a can having a capacity of 290 ml is formed.

First, a circular metal plate 100 is punched out from a flat metal plate by punching (step ST1). Next, the circular metal plate 100 is formed into a cup shape by drawing and ironing in which the metal plate 100 is repeatedly pressed with a mold such as a pump or die having an appropriate shape and size (step ST2). For example, as shown in steps ST2-1 to ST2-3 in FIG. 5, the drawing and ironing process is carried out in a plurality of steps, and the intermediate molded product 200 having a bottomed cylindrical shape having a predetermined depth from a disc shape is formed from metal. The plate 100 is molded, and for the next step, the bottom of the intermediate molding 200 is molded into a dome shape as shown in ST2-4.

Next, the bottom 21 is formed on the molded intermediate product 200 (step ST3). Next, the open end of the intermediate molded product 200 forming the bottom 21 is trimmed so that the intermediate molded product 200 has a predetermined height (step ST4). Next, clear coating is applied to the trimmed intermediate product 200 (step ST5), and the neck 23 is formed (step ST6). For example, as shown in steps ST6-1 to ST6-4 in FIG. 5, the neck 23 is formed on the upper end of the trunk portion 22 by gradually reducing the diameter of the open end of the intermediate molded product 200 .

Next, the flange 24 is formed on the upper end of the neck 23 (step ST7), and the can body 11 is formed. Next, an amorphization treatment is performed so that 35% or more and 100% or less of the coating layer 140 on the inner surface of the can body 11 is amorphized (step ST8). As a specific example, the can body 11 is heat-treated so that the surface temperature of the can body 11 is heated to the melting point temperature of the coating layer 140 or more and the melting point temperature +30° C. or less, and the temperature is maintained for a predetermined time. For example, when a polyester resin having a melting point of 240°C is used as the resin material forming the coating layer 140, the surface temperature of the can body 11 is heated to 250°C. After that, by rapidly cooling the can body 11, 35% or more and 100% or less of the polyester resin constituting the coating layer 140 is made amorphous.

Next, the can body 11 is filled with the beverage 90 (step ST9), and then the upper lid 12 is placed on the upper end of the can body 11, and the flange 24 of the can body 11 and the flange 32 of the upper lid 12 are rolled up. (step ST10). Thereby, the two-piece can 1 is manufactured.

According to the two-piece can 1 configured in this way, the coating layer 140 is provided on the metal plate 100 for forming the can body 11 , and drawing and ironing is performed on the coating layer 140 . The processing followability of the Sn plating layer 120 is improved, and the state in which Sn is uniformly distributed in the Sn plating layer 120 is maintained from before forming the can body 11 to after forming the can body 11 . That is, in the can body 11, the Sn plating layer 120 can prevent Sn from being present in a sea-island pattern and then forming the Sn in a striped pattern. As a result, the Sn in the Sn plated layer 120 after forming the can body 11 is maintained in a uniform state, resulting in high corrosion resistance.

After forming the can body 11 from the metal plate 100, the can body 11 is heat-treated at a temperature equal to or higher than the melting point of the coating layer 140, and then rapidly cooled to make the coating layer 140 amorphous, and the coating layer 140 is formed. It is possible to reset the damage caused by the applied stress. Therefore, the can body 11 can have even higher corrosion resistance.

Further, the can body 11 is further improved in corrosion resistance because Fe of the base material 101 and Sn of the Sn plating layer 120 form an Fe--Sn alloy by drawing, ironing and heat treatment.

Also, the can body 11 is the thickness reduction rate when the thickness of the thinnest part of the body 22 is Tw and the thickness of the bottom 21 is Tb in forming the can body 11 from the metal plate 100 (( Tb−Tw)/Tb)×100 is set to 35%≦((Tb−Tw)/Tb)×100(%)≦60%. For example, the can body of the two-piece can 1 having a capacity of 300 ml is the thinnest of the can body 11 when the thickness of the metal plate 100 is 0.229 mm (the thickness excluding the coating layer 140 is 0.190 mm). The plate thickness Tw of the part is drawn and ironed to 0.108 mm. By setting such a plate thickness reduction rate, the can body 11 can be made into a container having pressure resistance even with a small amount of material.

Furthermore, by setting the Sn coating rate of the Sn plating layer 120 to 44% or more, the can body 11 can be provided with corrosion resistance to acidic beverages.

As described above, according to the two-piece can 1 according to one embodiment of the present invention, corrosion resistance can be improved.

The present invention is not limited to the above embodiment, and for example, the two-piece can 1 described above may have a shape having a capacity of 250 ml, 350 ml, or 500 ml in addition to the shape of 300 ml.

The present invention is not limited to the above-described embodiments, and can be variously modified in the implementation stage without departing from the scope of the invention. Moreover, each embodiment may be implemented in combination as much as possible, and in that case, the combined effect can be obtained. Furthermore, the above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiments, the problems described in the column of problems to be solved by the invention can be solved, and the effects described in the column of effects of the invention is obtained, the configuration from which this constituent element is deleted can be extracted as an invention.

In order to make the features of the present invention more specific, evaluation tests using each example and each comparative example will be described below. However, the scope of the present invention is not limited to the following examples.

[Example 1]
The can body 11 is subjected to a metal plate 100 having a Ni plating layer 110, a Sn plating layer 120, a Cr plating layer 130 and a coating layer 140 on a base material 101 without heat treatment, and the thickness reduction rate ((Tb-Tw) /Tb)×100 is 57%. The Ni plating layer 110 has a basis weight of 24 mg/m ² , the Sn plating layer 120 has a basis weight of 720 mg/m ² , and the Cr plating layer 130 has a basis weight of 23 mg/m ² . A polyester resin sheet having a melting point of 240° C. was used as the covering layer 140 and adhered onto the Cr plating layer 130 with an adhesive. The total thickness of the metal plate 100 was 0.175 mm, the thickness of the coating layer 140 was 25 μm, and the thickness of the adhesive layer was 2 μm.

[Example 2]
The can body 11 is provided with a Sn plating layer 120, a Cr plating layer 130, and a coating layer 140 on the base material 101, and is heat-treated. is 57%. The Sn plating layer 120 has a basis weight of 780 mg/m ² and the Cr plating layer 130 has a basis weight of 26 mg/m ² . A polyester resin sheet having a melting point of 240° C. was used as the covering layer 140 and adhered onto the Cr plating layer 130 with an adhesive. The total thickness of the metal plate 100 was 0.175 mm, the thickness of the coating layer 140 was 25 μm, and the thickness of the adhesive layer was 2 μm.

[Comparative Example 1]
The can body 11 is provided with a Ni plating layer 110, a Sn plating layer 120, a Cr plating layer 130 and a coating layer 140 on the base material 101, and the metal plate 100 subjected to heat treatment has a thickness reduction rate ((Tb-Tw) /Tb)×100 is 57%. The Ni plating layer 110 has a basis weight of 25 mg/m ² , the Sn plating layer 120 has a basis weight of 660 mg/m ² , and the Cr plating layer 130 has a basis weight of 22 mg/m ² . A polyester resin sheet having a melting point of 240° C. was used as the covering layer 140 and adhered onto the Cr plating layer 130 with an adhesive. The total thickness of the metal plate 100 was 0.175 mm, the thickness of the coating layer 140 was 25 μm, and the thickness of the adhesive layer was 2 μm.

[Comparative Example 2]
The can body 11 is provided with a Ni plating layer 110, a Sn plating layer 120, a Cr plating layer 130 and a coating layer 140 on the base material 101, and the metal plate 100 subjected to heat treatment has a thickness reduction rate ((Tb-Tw) /Tb)×100 is 57%. The Ni plating layer 110 has a basis weight of 25 mg/m ² , the Sn plating layer 120 has a basis weight of 1980 mg/m ² , and the Cr plating layer 130 has a basis weight of 22 mg/m ² . A polyester resin sheet having a melting point of 240° C. was used as the covering layer 140 and adhered onto the Cr plating layer 130 with an adhesive. The total thickness of the metal plate 100 was 0.175 mm, the thickness of the coating layer 140 was 25 μm, and the thickness of the adhesive layer was 2 μm.

[Comparative Example 3]
The can body 11 is provided with a Ni plating layer 110, a Sn plating layer 120, a Cr plating layer 130 and a coating layer 140 on the base material 101, and the metal plate 100 subjected to heat treatment has a thickness reduction rate ((Tb-Tw) /Tb)×100 is 57%. The Ni plating layer 110 has a basis weight of 25 mg/m ² , the Sn plating layer 120 has a basis weight of 1210 mg/m ² , and the Cr plating layer 130 has a basis weight of 22 mg/m ² . A polyester resin sheet having a melting point of 240° C. was used as the covering layer 140 and adhered onto the Cr plating layer 130 with an adhesive. The total thickness of the metal plate 100 was 0.175 mm, the thickness of the coating layer 140 was 25 μm, and the thickness of the adhesive layer was 2 μm.

[Comparative Example 4]
The can body 11 is provided with the Ni plating layer 110, the Cr plating layer 130 and the coating layer 140 on the base material 101, and is processed by the metal plate 100 that has not been heat-treated, and the thickness reduction rate ((Tb-Tw)/Tb) × Molded so that 100 is 57%. Note that the Sn plated layer 120 is not provided. The Ni plating layer 110 has a basis weight of 553 mg/m ² and the Cr plating layer 130 has a basis weight of 5 mg/m ² . A polyester resin sheet having a melting point of 240° C. was used as the covering layer 140 and adhered onto the Cr plating layer 130 with an adhesive. The total thickness of the metal plate 100 was 0.175 mm, the thickness of the coating layer 140 was 25 μm, and the thickness of the adhesive layer was 2 μm.

[Comparative Example 5]
The can body 11 is provided with the Ni plating layer 110, the Cr plating layer 130 and the coating layer 140 on the base material 101, and is processed by the metal plate 100 that has not been heat-treated, and the thickness reduction rate ((Tb-Tw)/Tb) × Molded so that 100 is 57%. Note that the Sn plated layer 120 is not provided. The Ni plating layer 110 has a basis weight of 574 mg/m ² and the Cr plating layer 130 has a basis weight of 59 mg/m ² . A polyester resin sheet having a melting point of 240° C. was used as the covering layer 140 and adhered onto the Cr plating layer 130 with an adhesive. The total thickness of the metal plate 100 was 0.175 mm, the thickness of the coating layer 140 was 25 μm, and the thickness of the adhesive layer was 2 μm.

[Comparative Example 6]
The can body 11 is coated with a non-heat-treated metal plate 100, which is a chromium-plated steel plate (TFS) having a Cr-plated layer 130 on a base material 101 and a coating layer 140 laminated thereon. It was molded so that Tw)/Tb)×100 was 57%. Note that the metal plate 100 does not have the Ni plated layer 110 and the Sn plated layer 120 . Also, the basis weight of the Cr plating layer 130 was set to 120 mg/m ² .

A polyester resin sheet having a melting point of 240° C. was used as the covering layer 140 and adhered onto the Cr plating layer 130 with an adhesive. The total thickness of the metal plate 100 was 0.175 mm, the thickness of the coating layer 140 was 25 μm, and the thickness of the adhesive layer was 2 μm.

[Comparative Example 7]
The can body 11 is provided with the Cr plating layer 130 and the coating layer 140 on the base material 101, and the metal plate 100 that has not been heat-treated has a plate thickness reduction rate ((Tb−Tw)/Tb)×100 of 69%. molded to be Note that the Ni plating layer 110 is not provided. The Sn plating layer 120 has a basis weight of 5600 mg/m ² and the Cr plating layer 130 has a basis weight of 0.5 to 2.0 mg/m ² . Epoxy paint was used for the coating layer 140 . The total thickness of metal plate 100 was 0.240 mm, and the thickness of coating layer 140 was 4 μm.

[Evaluation Test 1]
As evaluation test 1, the surface of the metal plate 100 used for forming the can body 11 of Examples 1 and 2, Comparative Examples 1 to 3, and Comparative Example 7 from which the coating layer 140 was removed was Sn-plated. The distribution of Sn in the layer 120 and the Sn in the Sn plating layer 120 on the surface from which the coating layer 140 on the inner surface of the can body 11 was removed after molding the can body 11 were confirmed using an electron microscope.

It was determined whether the Sn in the Sn plated layer 120 on the surface of the can body 11 from which the coating layer 140 was removed after molding the can body 11 was uniformly distributed or whether it was distributed in stripes.

[Evaluation test 2]
As evaluation test 2, the can body 11 of Example 1, Example 2, and Comparative Examples 1 to 6 in which heat treatment and rapid cooling treatment were performed at 228 ° C. to make the coating layer 140 amorphous after molding, and An accelerated test was performed on the can bodies 11 of Examples 1 and 2 and Comparative Examples 1 to 3 which were subjected to heat treatment and rapid cooling treatment at 250°C. As conditions for the accelerated test, the can body 11 was placed at a temperature of 55° C., and after 240 hours had elapsed, the can body 11 was taken out and the state of the inner surface of the can body 11 was checked.

As evaluation criteria, ◯ indicates no corrosion on the inner surface of the can body 11, □ indicates slight corrosion on the inner surface of the can body 11, Δ indicates corrosion on the inner surface of the can body 11, and Δ indicates the inner surface of the can body 11. X indicates that there is general corrosion on the can body 11, XX indicates that there is severe corrosion on the inner surface of the can body 11, and XXX indicates that many severe corrosion occurs on the entire inner surface of the can body 11.

[Evaluation test 3]
As evaluation test 3, the can body 11 of Example 1, Example 2, and Comparative Examples 1 to 6 in which heat treatment and rapid cooling treatment were performed at 228 ° C. to make the coating layer 140 amorphous after molding, 250 ° C. Example 1, Example 2, and Comparative Examples 1 to 3 in which heat treatment and quenching treatment were performed at , and the can body 11 of Comparative Example 7 in which heat treatment was performed at 205 ° C. for hardening the coating layer 140 . After the beverage 90 was put in and the upper lid 12 was rolled up, sterilization was performed, and then the condition of the inner surface of the can body 11 was checked.

As evaluation criteria, ⊚ indicates that there is no corrosion on the inner surface of the can body 11, ∘ indicates that there is corrosion on the inner surface of the can body 11, and from the inner surface of the can body 11 to a depth of about 10% of the plate thickness. □ indicates corrosion, ◇ indicates corrosion from the inner surface of the can body 11 to a depth of about 25% of the plate thickness, and ◇ indicates corrosion from the inner surface of the can body 11 to a depth of about 50% of the plate thickness. Δ indicates that there is some corrosion, ▲ indicates that there is corrosion from the surface of the inner surface of the can body 11 to a depth of about 75% of the plate thickness, and x indicates that there is a lot of corrosion and piercing corrosion on the inner surface of the can body 11 .

For the beverage 90, a malt-based carbonated alcoholic beverage and an acidic carbonated beverage were used. For malt-based carbonated alcoholic beverages, the two-piece can 1 was warmed after being cold-packed, and for acidic carbonated beverages, the two-piece can 1 was warmed after being cold-packed.

[Results of evaluation test]
As results of the evaluation tests 1 to 3, the results of the evaluation tests are shown in FIGS. 8 to 10 show the outline of the state of the inner surface of the can body 11 in addition to the judgment results based on the evaluation criteria of the evaluation test 2. FIG.
As shown in FIGS. 6 and 7, in the evaluation test 1, in Examples 1 and 2, Sn was uniformly distributed on the inner surface of the can body 11 before and after the can body 11 was formed. On the other hand, in Comparative Examples 1 to 3, Sn is distributed in a sea-island pattern on the inner surface of the can body 11 before molding, and Sn is distributed in stripes on the inner surface of the can body 11 after molding. was In Comparative Example 7, Sn was uniformly distributed on the inner surface of the can body 11 before molding, but Sn was distributed in stripes on the inner surface of the can body 11 after molding. From this, according to the can bodies 11 of Examples 1 and 2 according to the present embodiment, Sn is uniformly distributed on the inner surface of the can body 11 even after molding. It was found that the entire inner surface was in a state of having corrosion resistance.

As shown in FIGS. 8 to 10, in the evaluation test 2, the can body 11 subjected to the heat treatment at 228° C., which is lower than the melting point of the coating layer 140, for amorphization after molding, had an inner surface There was a lot of corrosion on the On the other hand, the can body 11 subjected to heat treatment at 250° C., which is higher than the melting point of the coating layer 140, for amorphization after molding had only mild corrosion on the inner surface. From this, it has been clarified that the corrosion resistance is improved by performing the heat treatment at the melting point temperature of the coating layer 140 or higher to make the coating layer 140 amorphous.

Further, as shown in FIG. 11, as a result of the evaluation test 3, the can bodies 11 of Examples 1, 2, Comparative Examples 1 to 3, and Comparative Example 7 are malt-based carbonated alcoholic beverages and acidic carbonated beverages. In both cases, the corrosion was from the surface of the inner surface of the can body 11 to a depth of about 10% of the plate thickness at the maximum, and good results were obtained as a whole. When the can bodies 11 of Comparative Examples 4 to 6 were filled with malt-based carbonated alcoholic beverages, numerous corrosion and perforation corrosion were observed on the inner surface of the can bodies 11 .

From the results of the evaluation tests 1 to 3 described above, it was shown that by configuring the can body 11 according to the embodiment described in Examples 1 and 2, high corrosion resistance can be obtained.
The description equivalent to the invention described in the original claims of the present application is added below.
[1] A Sn plating layer of 100 mg/m2 or more and 1500 mg/m2 or less provided on a steel base material, a Cr plating layer of 6 mg/m2 or more and 100 mg/m2 or less provided on the Sn plating layer, and the above Laminated on the Cr plating layer, having a coating layer made of a thermoplastic resin, having a Ni plating layer between the base material and the Sn plating layer, and not subjected to heat treatment or A punching step of punching a metal plate heat-treated without having the Ni plating layer on the base material into a disc shape;
A molding step of drawing and ironing the disc shape to a bottomed cylindrical can body so that the coating layer is on the inner surface;
with
In the forming step, the thickness of the thinnest part of the cylindrical wall of the can body is Tw, and the thickness of the bottom of the can body is Tb. ((Tb-Tw)/Tb) × 100, which is the thickness reduction rate to the barrel,
35%≦((Tb−Tw)/Tb)×100(%)≦60%
A method for manufacturing a two-piece can, wherein the drawing and ironing process is performed.
[2] The Sn plated layer of the metal plate is uniformly coated on the base material in a granular form and has a coverage of 44% or more and 63% or less, and a part of the Sn plated layer is the The method for producing a two-piece can according to [1], wherein the can is alloyed with Fe of the base metal.
[3] The method of manufacturing a two-piece can according to [1], wherein the metal plate has the Ni plating layer of less than 200 mg/m 2 between the base material and the Sn plating layer.
[4] The method for producing a two-piece can according to [1], wherein the coating layer is composed of an amorphized polyester resin film having a thickness of 2 μm or more and 14 μm or less and a melting point of 200° C. or more and 260° C. or less. .
[5] After the molding step, further comprising a heating step of heating the can body to the melting point of the coating layer and then rapidly cooling the coating layer to make the coating layer amorphous to 35% or more and 100% or less, [ 4] method for manufacturing a two-piece can.
[6] A Sn plating layer of 100 mg/m2 or more and 1500 mg/m2 or less provided on a steel base material, a Cr plating layer of 6 mg/m2 or more and 100 mg/m2 or less provided on the Sn plating layer, and the above Laminated on the Cr plating layer, having a coating layer made of a thermoplastic resin, having a Ni plating layer between the base material and the Sn plating layer, and not subjected to heat treatment or Molded into a cylindrical shape with a bottom using a metal plate heat-treated without having the Ni plating layer on the base material,
The thickness reduction rate from the cylindrical metal plate ((Tb−Tw)/Tb), where Tw is the thickness of the thinnest portion of the cylindrical wall portion and Tb is the thickness of the bottom portion. ×100 is
35%≦((Tb−Tw)/Tb)×100(%)≦60%
This is the can barrel.
[7] The Sn-plated layer of the metal plate is uniformly coated on the base material in a granular form and has a coverage of 44% or more and 63% or less, and a part of the Sn-plated layer is the The can body of [6], which is alloyed with Fe of the base material.
[8] The can body of [6], wherein the metal plate has the Ni plating layer of less than 200 mg/m 2 between the base material and the Sn plating layer.
[9] The can body of [6], wherein the coating layer is made of an amorphized polyester resin film having a thickness of 2 μm or more and 14 μm or less and a melting point of 200° C. or more and 260° C. or less.
[10] The can body of [9], wherein the coating layer is amorphous to 35% or more and 100% or less.
[11] a steel base material;
a Sn plating layer of 100 mg/m2 or more and 1500 mg/m2 or less provided on the base material;
a Cr plating layer of 6 mg/m2 or more and 100 mg/m2 or less provided on the Sn plating layer;
A coating layer laminated on the Cr plating layer and made of a thermoplastic resin;
A metal plate with
[12] The Sn-plated layer is uniformly coated on the base material in a granular form and has a coverage of 44% or more and 63% or less. The metal plate of [11], which is alloyed with
[13] The metal plate according to [11], which has a Ni plating layer with a basis weight of less than 200 mg/m 2 between the base material and the Sn plating layer.
[14] The metal plate of [11], wherein the coating layer is made of a polyester resin film having a thickness of 2 μm or more and 25 μm or less and a melting point of 200° C. or more and 260° C. or less.

DESCRIPTION OF SYMBOLS 1... Two-piece can, 11... Can body, 12... Upper lid, 21... Bottom (bottom part), 22... Body part (wall part), 23... Neck, 24... Flange, 31... Panel part, 32... Flange, 90... Beverage (Contents) 100... Metal plate 101... Base material 110... Ni plating layer 120... Sn plating layer 130... Cr plating layer 140... Coating layer 200... Intermediate molding.

Claims (8)

A Sn plating layer of 100 mg/m ² or more and 1500 mg/m 2 or less provided on a steel base material, a Cr plating layer of ^{6 mg/m 2 or more and 100 mg/m 2 or less} provided on the Sn plating layer , the Cr A metal plate having a coating layer composed of a thermoplastic resin laminated on the plating layer , and a Ni plating layer between the base material and the Sn plating layer, and not subjected to heat treatment, is a disk. A punching process of punching out into a shape,
A forming step of drawing and ironing the disc-shaped metal plate into a bottomed cylindrical can body so that the coating layer is on the inner surface;
with
In the forming step, the thickness of the thinnest part of the cylindrical wall of the can body is Tw, and the thickness of the bottom of the can body is Tb. ((Tb-Tw)/Tb) × 100, which is the thickness reduction rate to the barrel,
35%≦((Tb−Tw)/Tb)×100(%)≦60%
A method for manufacturing a two-piece can, wherein the drawing and ironing process is performed. The Sn-plated layer of the metal plate is uniformly coated on the base material in a granular form and has a coverage of 44% or more and 63% or less, and a part of the Sn-plated layer covers the base material. 2. A method of making a two-piece can according to claim 1, which is alloyed with Fe. 2. The method of claim 1 , wherein the Ni plating layer is less than 200 mg/m< ² >. 1 to 1, further comprising a heating step of heating the can body to the melting point of the coating layer after the forming step and then rapidly cooling the can body to make the coating layer amorphous to 35% or more and 100% or less. 4. A method of manufacturing a two -piece can according to any one of claims 3 . A can body for a two-piece can,
A Sn plating layer of 100 mg/m ² or more and 1500 mg/m 2 or less provided on a steel base material, a Cr plating layer of ^{6 mg/m 2 or more and 100 mg/m 2 or less} provided on the Sn plating layer , the Cr A disc-shaped plate having a coating layer made of a thermoplastic resin laminated on the plated layer , and a Ni plated layer provided between the base material and the Sn plated layer, and not subjected to heat treatment. formed into a bottomed cylindrical shape using a metal plate of
The thickness reduction rate from the cylindrical metal plate ((Tb−Tw)/Tb), where Tw is the thickness of the thinnest portion of the cylindrical wall portion and Tb is the thickness of the bottom portion. ×100 is
35%≦((Tb−Tw)/Tb)×100(%)≦60%
This is the can barrel. The Sn-plated layer of the metal plate is uniformly coated on the base material in a granular form and has a coverage of 44% or more and 63% or less, and a part of the Sn-plated layer covers the base material. 6. The can body of claim 5 , which is alloyed with Fe. 6. The can body of claim 5 , wherein the Ni plating layer is less than 200 mg/m< ² >. The can body according to any one of claims 5 to 7, wherein the coating layer is amorphized to 35% or more and 100% or less.

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