JP3018049B2 - Method for manufacturing easy-open can lid with no repair on inner and outer surfaces using resin laminated steel sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to is a method of manufacturing a metal container closure, in particular a part of the can lid or nearly steel easy Hirakikanfuta the entire surface thereof can be easily opened by hand, the
The easy-open can made of steel plate manufactured according to the present invention is used for beverage cans, general food cans, and a wide variety of other uses.

[0002]

2. Description of the Related Art An easy-open can lid, which can easily open a part or substantially the entire surface of a container lid by hand, is of a tear-off type in which a handle and an opening piece are torn off and separated from a can body, and both a handle and an opening piece are opened. A stay-on tub method that remains fixed to the can body after the can has been put to practical use. In either system, most easy-open can lids are manufactured from aluminum plates for manufacturing technology reasons, and steel plates are currently used for some limited applications.

[0003] As a typical example of the prior art, a coated aluminum or steel plate is used as a material, and after punching into a basic lid shape, the lid body is placed on a flat lower mold, and has a required contour shape from the upper surface thereof. By pressing the sharp blade and cutting the blade into the lid main body, an opening piece shape surrounded by a cutting guide groove having a V-shaped cross section (FIG. 5) has been formed.

[0004] The basic feature of the steel material itself is its high strength. In order to form a cutting guide groove that can be easily opened manually, a sharp blade having a thickness of about half to 2/3 of the plate thickness before processing is required. Intense pressing is needed. When the depth of the cutting guide groove is too shallow, the can opening property is poor, and when the depth is too deep, the impact strength against external shocks is insufficient. Therefore, considerable accuracy is required.

[0005] Therefore, although a considerable accuracy is required for a working tool, there is a drawback that the tool life cannot be maintained in the case of a steel plate which requires a sharp pressing of a sharp blade. In addition, in order to ensure corrosion resistance to the contents or to prevent the occurrence of rust on the outer surface, it is necessary to repair and coat a portion where the metal surface is exposed by processing the cutting guide groove. As measures for extending the tool life, Japanese Patent Application Laid-Open Nos. Sho 55-70434 and
As disclosed in Japanese Patent Publication No. 175034 and the like, a method of forming a cutting guide groove by composite extrusion has been proposed.
This known method was premised on the use of steel sheets, and was an effective measure for extending tool life,
Since the cross-sectional structure of the cutting guide groove is complicated, the coating does not spread to all parts in the cutting guide groove by the ordinary spray coating method, and there is a defect that sufficient corrosion resistance cannot be obtained even when repair painting is performed.

[0006]

In the prior art using a sharp blade, aluminum is considered to be preferable as a material thereof, and a material using a steel plate is used only for very limited applications. Is as described above. The main reasons are the strong resistance of the steel plate to the intense pressing of the sharp blade, the very short tool life, the breakage of the coating on the steel plate surface due to the processing, the entire circumference of the cutting guide groove or the swaged part of the handle, etc. On the other hand, it was necessary to apply repair painting, and there was concern about corrosion resistance.

On the other hand, in response to the increasing awareness of global environmental issues in recent years, it has been required to focus on products suitable for recycling. Even in metal cans, the can body and can lid are formed of the same material. In addition, the importance of so-called “monometal cans” has been emphasized. At present, most metal cans use steel body cans, which have excellent openability and do not require repair painting of the inner and outer surfaces.
The emergence of measures that can be manufactured with high productivity has been eagerly awaited. Naturally, the steel sheet itself is excellent in economic efficiency, and it is expected that by using steel plates for both the can body and the can lid, the product will be more economical and easy to reuse as resources.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems at once, and the gist thereof is as follows . (1) Elongation at break 50-300%, tensile modulus 60 kg /
mm ² or more, a resin laminate steel sheet having a resin film having a thickness of 10~80μm on both sides, on the periphery of the opening piece, the main constituent of the thin portion thinnest portion has a thickness of 1/2 or less of the unprocessed portion thickness the cutting guide groove of an element, be formed by a composite extrusion
Inner and outer surfaces free repair of easy Hirakikanfuta manufacturing method of a resin laminated steel plate, characterized in that that. (2) The composite extrusion corresponds to the opening piece of the lid body 1
The thickness of the connecting piece 7, which is the thinnest part, is the thickness before processing.
Pre-push upward or downward to a thickness of 1/2 or less
Processed part extruded upwards or downwards after extrusion processing
Extrusion process that pushes back to the level before processing.
The resin laminated steel sheet according to the above (1),
Method for manufacturing easy-to-repair can openable inner and outer can lids. (3) In the pre-extrusion process, the bite groove 16 is
The laminated steel sheet according to the above (2), which is provided.
Manufacturing method of easy-open can lid with no repair of inner and outer surface by using.

Hereinafter, the present invention will be described in detail. Steel sheet used in the present invention, the thickness t _0: 0.150 to .300
mm, having mechanical properties of hardness ( _HR30T ): 54 to 68 and elongation: about 10 to 40%. On the surface of this steel sheet, Sn, Cr, Ni, Al,
A metal coating of one or more types of Zn is applied, and a resin film having excellent adhesion, workability, and corrosion resistance is laminated via a chromate-treated film to eliminate the need for repair coating after processing.

[0010] Specifically, the adhesion amount is 0.5 to 3.0 g / m.
^TwoTin-plated steel sheet subjected to chemical treatment after tin plating
0.3-2.0 g / m^TwoConversion treatment after nickel plating
Nickel plated steel sheet, Sn and Ni adhesion amount
0.5 to 2.0 g / m each ^Two, 0.01-0.5 g /
m^TwoIs subjected to a chemical conversion treatment after plating in the order of Ni and Sn
/ Ni plated steel sheet, metal Cr adhesion amount 50-200mg /
m^Two, Cr oxide 5-30 mg / m^TwoNormal TFS (Ti
n Free Steel)
For example, a steel plate treated with a rote treatment.

The elongation at break is 50 on both sides of the surface-treated steel sheet.
300%, a tensile modulus of 60 kg / mm ² or more, thickness 1
The presence of a resin film of 0 to 80 μm is required. This resin film, when processing the cutting guide groove by composite extrusion molding,
By following the substrate with good adhesion and having excellent workability of the film itself, it completely covers the substrate even after processing, and is an important entity that eliminates the need for repair painting that has been required conventionally. When the can is opened, a specific resin is used to prevent only the resin from remaining locally on the cut end surface of the cutting guide groove (a film remaining phenomenon, hereinafter referred to as a feather) and impairing the appearance impression. There is a need.

It is important that the elongation at break is in the range of 50 to 300% as a physical property of the resin film required for the present invention. If the elongation at break is less than 50%, a large number of defects are generated in the resin film due to insufficient elongation, which is not preferable for the formation of a thin portion at the time of composite extrusion described later. On the other hand, when the elongation at break of the resin film exceeds 300%, a problem occurs when the can is opened. That is, when the can is opened, it is necessary to break the laminated resin film along the cutting guide groove. If the elongation is too high, the film elongates long before the breakage, and a film remaining phenomenon is easily generated. It is necessary to keep the elongation below. The elongation property satisfying both the workability and the feather property needs to be in the range of 50 to 300%, more preferably in the range of 70 to 200%.

The elongation characteristics of the laminated resin film are measured by peeling the resin film from the substrate and following a method according to JIS C2318. The second important point as the physical properties of the resin film is that the tensile elastic modulus is 60 kg / mm ² or more, more preferably 90 kg / mm ² or more.
This is where a resin film having a tensile modulus of not less than kg / mm ² is required. The tensile modulus is the ratio of the tensile stress within the tensile proportional limit to the corresponding strain.If there is no linear part in the stress-strain curve in the tensile test,
It is obtained from the inclination of the tangent at the deformation start point. This elastic modulus indicates the degree of hardness of the resin itself, and the greater the elastic modulus, the stronger the stiffness, and it is expected that excellent workability is imparted by keeping the difference in strength from the base steel sheet small. . By adopting a resin film having a tensile modulus of 60 kg / mm ² or more, more desirably 90 kg / mm ² or more, the resin film is shaved at the mold R portion during compound extrusion processing, and build-up is performed. It can effectively prevent the formation of flaws and the like in the frictional portion with the mold, prevent the occurrence of film defects during processing, and open the way to no repair of the inner and outer surfaces.

The thickness of the laminated film of the present invention is 10 to
Although it is within a range of 80 μm, a range of 16 to 60 μm is particularly effective in consideration of performance stability and economy. It is obvious that if the thickness is too thin, processing defects are likely to occur. 6
When the film thickness exceeds 0 μm, especially 80 μm or more, the corrosion resistance after processing proceeds in a better direction. However, when the cutting guide groove is broken (when the can is opened), the film elongates long before breaking, and the film remains. Adopting an excessively thick coating is disadvantageous because the phenomenon is likely to occur.

Specific examples of the resin film used include films of biaxially oriented polyester, biaxially oriented nylon, unoriented polypropylene, biaxially oriented polypropylene, polyethylene and the like. As a laminating method, the film itself is thermally bonded, or a thermosetting adhesive is applied, and the film is laminated on both surfaces of the steel plate as described above. When a surface-treated steel sheet having a resin film described in detail above is formed into an easily-openable lid, the processing method is extremely important. That is,
The formation of a cutting guide groove by a sharp blade pressing method, which is a typical prior art, is not preferable because it also breaks the resin film and requires repair painting after molding. In order to form a cutting guide groove that guarantees easy opening without breaking the resin film, it is important to stretch the entire material by elongation deformation and to form a thin portion formed with a gradual thickness change. is there. The peripheral edge portion of the opening piece, the thinnest part thickness of the unprocessed portion thickness 1
By forming a cutting guide groove whose main component is a thin-walled portion having a thickness of not more than / 2, it is possible to obtain an easy-open can lid made of a steel plate which has excellent can-opening property and does not require repair painting of inner and outer surfaces. .

As a specific processing method, a portion corresponding to the shape of the opening piece is upwardly or downwardly pressed by pressing an important portion of the lid body using an upper and lower die substantially corresponding to the shape and dimensions of the opening piece. Extrusion molding is performed. At this time, the peripheral edge portion of the opening is extended between the upper and lower dies so as to reach a desired thickness, thereby forming a thin portion having a gradual change in plate thickness. The thickness of the thinnest part is required to be 以下 or less of the thickness before processing from the viewpoint of openability.

By this processing, the breaking position at the time of opening the can is determined. However, in order to improve the opening property and to make the shape of the opening after the opening of the can desirable, the opening piece portion extruded upward or downward. Is pushed back to the level before processing.
At this time, the thin portion having a gentle plate thickness change formed by the extrusion process is bent into a V-shaped cross section to form a thin cutting guide groove. The depth or the thickness of the thinnest portion of the cutting guide groove can be set to a desired value according to the workability of the material by appropriately setting the processing conditions. Processing conditions are selected according to the processability.

In these series of processing steps, the resin film having the above-mentioned properties is uniformly stretched together with the substrate, and no processing defects are generated. Therefore, there is no need for repair coating after processing, and good corrosion resistance is ensured. Can be. In addition, since the processing is based on press working such as extrusion or push-back, there is no problem of tool life seen in the sharp blade pressing method, and excellent productivity is guaranteed.

The main feature of the present invention is to optimize a cutting guide groove present at a peripheral portion of an opening piece, and a tear-off system in which a handle and an opening piece are torn apart to be separated from a can body, a handle and an opening. It is possible to apply both types of the stay-on tub method in which both pieces remain fixed to the can body even after the can is opened.

[0020]

Embodiments of the present invention will be described below. Example 1 A thin steel plate having a thickness of 0.260 mm and a hardness of 63 (H _R30T ) was subjected to electrotin plating with an adhesion amount of 1.1 g / m ^{2 on} the surface. After tin is heated and melted to obtain a surface having a specular gloss, an electrolytic post-treatment is performed in a treatment bath mainly composed of chromic acid, and the metal chromium 8 mg / m ² and the hydrated chromium oxide 12 mg / m 2 A chromate film having ² (as Cr) was formed. After washing and drying, the steel sheet was heated, and a 50 μm biaxially stretched polypropylene resin film was laminated on both sides of the steel sheet using a modified polypropylene-polyethylene copolymer resin as an adhesive layer. The biaxially stretched polypropylene resin film used has an elongation of 90% and a tensile modulus of 26.
It was 0 kg / mm ² .

When a steel plate having a biaxially stretched polypropylene resin film on both sides is formed into an easy-open can lid as shown in FIG. 1, as shown in FIG. , 6 were pressed into key portions of the lid body, thereby extruding a portion corresponding to the opening piece 2 upward. At this time, the peripheral edge of the opening piece 2, the lid main body 1, and the connecting piece 7 were processed so as to form a thin portion which was inclined downward and widened and had a gradual change in plate thickness due to elongation. Next, as shown in FIG. 3, the lid main body is placed on a lower mold 9 having a recessed groove 8 at a portion corresponding to the peripheral edge of the opening piece 2 so that the opening piece 2 comes inside the recessed groove 8. 1 was placed and pressed by an upper mold 10 having a flat lower surface.

By this operation, the continuous piece 7 having a gradual change in plate thickness is bent downward substantially in a V-shape from the middle portion, and protrudes into the concave groove 8. Thus, a thin cutting guide groove 4 having a V-shaped cross section is formed at the periphery of the opening piece 2 on the upper surface of the lid main body 1. The easy-open can lid thus formed was subjected to an evaluation of can-opening property by measuring a tearing force of the opening piece and an electric current test for examining the degree of destruction of the resin film on the inner and outer surfaces of the can. The openability of the molded product (the force to raise the handle and the force to tear off the opening piece) is 2.0k
g or less, and the amount of current supplied to the resin film was about 0.3 mA, which was excellent in soundness and satisfied the target. In addition, no feather was noticeable visually around the cut end of the cut guide groove.

Example 2 Using a two-layer polyester resin film having a different melting point on the same plated steel sheet as in Example 1, a low-melting-point resin was thermally bonded to the steel sheet side to form a polyester resin film on both sides. Laminated. At this time, the total thickness of the film used was 25 μm, and the upper polyester resin layer having stretch orientation had an elongation of 110% and a tensile modulus of 40%.
It was 0 kg / mm ² .

When a steel plate having a polyester resin film on both sides is used to form an easy-open can lid as shown in FIG. 1, the upper and lower molds corresponding to the shape and size of the opening piece are formed as shown in FIG. With portions 5 and 6, a portion corresponding to the opening piece 2 was extruded downward. At this time, the peripheral portion of the opening piece 2, the lid main body 1 and the connecting piece 7 are formed so as to form a thin portion which is inclined upward and wide and has a gradual change in plate thickness due to elongation. At the same time, a biting groove 16 is provided in the peripheral edge of the lower surface, and then the opening piece is pressed upward, so that the thin portion having a gradual change in plate thickness is V-shaped upward (FIG. 4B). ) To form a cutting guide groove.
The presence of the biting groove 16 is intended to improve the openability by forming a remarkably thin portion between the cutting guide groove 4 and the biting groove 16, and the steel plate thickness of the thinnest portion is 6
It was adjusted to be 0 μm. The polyester resin film was formed in the same manner as the steel plate, and the film thickness remaining on the surface of the thinnest portion was about 6 μm.

The openability of the molded product is 1.8 kg or less and the can is opened without any problem.
mA and 0.9 mA on the outer surface side were satisfactory enough for practical use. In addition, no feather was noticeable visually around the cut end of the cut guide groove. Example 3 Sheet thickness 0.180 mm, hardness ( _HR30T ) 64, elongation 24%
Was plated on both sides of a steel sheet having a thickness of 0.58 g / m ² and subjected to a chromate treatment comprising 5 mg / m ^{2 of} metallic chromium and 12 mg / m ^{2 of} hydrated chromium oxide (as Cr). After washing and drying, the steel sheet was heated, and a 40 μm biaxially stretched nylon film was laminated via a thermosetting epoxy adhesive. This nylon film had an elongation of 90% and a tensile modulus of 130 kg / mm ² .

A steel sheet having a biaxially stretched nylon resin film on both surfaces was worked in the same manner as in Example 2 so that the thickness of the thinnest steel sheet became 50 μm. The resin film is formed in the same manner as a steel plate, and the film thickness remaining on the thinnest part surface is about 11
μm. The openability of the molded product is 1.6 kg or less and the can is opened without any problem.
1 mA and 0.08 mA on the outer surface side were satisfactory enough for practical use. In addition, no feather was noticeable visually around the cut end of the cut guide groove.

Comparative Example 1 A 50 μm non-stretched polypropylene resin film was laminated on both sides of the same steel plate as in Example 1 using a modified polypropylene-polyethylene copolymer resin as an adhesive layer. The unstretched polypropylene resin film used was
It had an elongation of 470% and a tensile modulus of 50 kg / mm ² .

Using this steel sheet as a raw material, an easy-open can lid having a thin cutting guide groove having a V-shaped cross section was prepared in the same manner as in Example 1. When pressing important parts of the lid body with the upper and lower dies corresponding to the shape and dimensions of the opening piece, the die corner R
A phenomenon in which the resin film was scraped off at the portion and the resin was built up was observed. The openability of the molded product (the force to raise the handle and the force to tear off the opening piece) is excellent at 2.0 kg or less, and the electric current of the resin film is about 1.5 mA, which is judged to be practical in terms of corrosion resistance. However, the film remained sharply around the cut guide groove which was broken at the time of opening, giving an uncomfortable appearance, and there was a problem in practicality.

Comparative Example 2 A polystyrene film having a thickness of 40 μm was laminated on the same plated steel plate as in Example 1 via a thermosetting epoxy adhesive. This film had a breaking elongation of 40% and a tensile modulus of 120 kg / mm ² . When this steel sheet was processed in the same manner as in Example 2, the current value of the resin film showed a very large value of 540 mA, and many defects were found in the resin film inside the cutting guide groove, and the practicality was improved. There was nothing.

[0030]

As described above, the manufacturing method of the easy-open can lid according to the present invention specifies a material and a processing method, that is, uses a resin film having characteristics conforming to the processing method of the present invention and a sharp blade. It is constructed by adopting a complex extrusion processing method. Therefore, it is possible to completely eliminate the problems of the service life of the working tool, the problem that requires repair painting, and the uneasiness of the corrosion resistance, which are the major problems of the prior art.

If a steel plate easy-open can lid is put to practical use, it will be possible to make it into a “monometal can”, and it will be possible to provide the market with products suitable for recycling in response to recent global environmental problems. It is. Naturally, the steel sheet itself is excellent in economic efficiency, and it is expected that by using steel plates for both the can body and the can lid, the product will be more economical and easy to reuse as resources.

[Brief description of the drawings]

FIG. 1 is a perspective view of a can lid having a tear-opening piece formed according to the present invention.

FIG. 2 is a longitudinal sectional view showing the procedure of the present invention in the order of steps.

FIG. 3 is a longitudinal sectional view showing the procedure of the present invention in the order of steps.

FIG. 4 (a) is a longitudinal sectional view showing a state in which a dish-shaped opening piece having a biting groove on the lower peripheral edge is formed on the entire lid;
(B) is a longitudinal sectional view showing a state where a cutting guide groove is formed from the state of (a).

FIG. 5 is a sectional view showing a cutting guide groove having a V-shaped cross section by a conventional sharp blade pressing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lid body 2 Opening piece 4 Cutting guide groove 5 Upper die 6 Lower die 7 Connecting piece 8 Recessed groove 9 Lower die 10 Upper die 16 Biting groove

──────────────────────────────────────────────────続 き The continuation of the front page (72) Inventor Keiji Taniuchi 2-6-7 Nishikojiya, Ota-ku, Tokyo Limited company Tani Kei Seisakusho (56) References JP-A-64-83328 (JP, A) 56-117843 (JP, A) JP-A 64-15235 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B65D 1/12 B21D 51/44

Claims (3)

(57) [Claims] An elongation at break of 50 to 300% and a tensile modulus of elasticity of 6
0 kg / mm ² or more, using a resin laminated steel sheet having a resin film with a thickness of 10 to 80 μm on both sides, on the periphery of the opening piece,
A cutting guide groove having a thin portion having a thickness of 1/2 or less of a thickness of an unprocessed portion or less as a main component is formed by a composite extrusion process. A method for manufacturing an easily-openable can lid. 2. The method according to claim 1, wherein the composite extrusion is performed by opening the lid body.
The part corresponding to the piece is processed by the thickness of the connecting piece 7 which is the thinnest part.
Upper or lower so that the thickness is less than 1/2 of the front plate thickness
Pre-extrusion, then extruded upward or downward
Extrusion that pushes back the processed part to the level before processing
The resin-laminated steel according to claim 1, wherein the steel is processed.
A method for manufacturing an easy-open can lid with no inner and outer surfaces that requires repair. 3. In the pre-extrusion process, a bite
The resin product according to claim 2, wherein a groove (16) is provided.
Manufacturing method of easy-open can lid with no repair on inner and outer surfaces using multi-layer steel plate.