JPH06122438A - Easy opening can lid with resin laminated steel plate without repair on the inner and outer surfaces - Google Patents

Abstract

(57) [Summary] [Object] The present invention forms a cutting guide groove in a steel sheet having a resin film having a specific mechanical property and a thickness by a composite extrusion process, and an opening without repair painting of the inner and outer surfaces is required. The purpose is to obtain a steel plate easy-open can lid having excellent can property. [Structure] Breaking elongation 50-300%, tensile elastic modulus 60k
A resin film having a thickness of g / mm ² or more and a thickness of 10 to 80 μm is laminated on both sides of the steel sheet with good adhesion. In this steel sheet, a cutting guide groove having a thin portion having a thinnest portion thickness of ½ or less of a thickness before processing as a main constituent element is formed on the peripheral edge portion of the opening piece by complex extrusion molding. [Effect] Since pressing processing with a sharp blade unlike the conventional method is not performed, a laminated film having excellent workability can be expected to have excellent corrosion resistance without causing film breakage during processing. By controlling the thickness of the thinnest part, it is possible to obtain a lid having good can openability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal container lid, and more particularly to a steel plate easy-open can lid which can easily open a part or almost the entire can lid by hand. Used in a wide range of applications.

[0002]

2. Description of the Related Art An easy-opening can lid that allows a part or almost the entire surface of a container lid to be opened easily by hand is a tear-off system in which the handle and the opening piece are torn off and the can body is separated, and both the handle and the opening piece are opened. The Steintab method, which remains fixed to the can body even after the can is put into practical use, has been put into practical use. In any of the methods, most of the easy-open can lids are manufactured from aluminum plates for the reasons of manufacturing technology, and steel plates are currently used for some limited purposes.

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 die, and a desired contour shape is provided from the upper surface thereof. By pressing a sharp blade and causing the blade edge to bite into the lid body, an opening piece shape surrounded by a cutting guide groove (FIG. 5) having a V-shaped cross section was formed.

The basic characteristic of the steel material itself is that it has a high strength, and in order to form a cutting guide groove that can be opened easily by hand, a sharp blade that reaches half to 2/3 of the thickness before processing can be used. Vigorous pressure is required. If the depth of this cutting guide groove is too shallow, the can openability will be poor, and if it is too deep, it will result in insufficient impact strength against shocks from the outside, etc. Therefore, considerable precision is required.

Therefore, although the machining tool is required to have a considerable accuracy, it has a drawback that the tool life cannot be maintained in the case of a steel plate which requires a sharp pressing by a sharp blade. Further, in order to secure the corrosion resistance to the contents or prevent the rusting of the outer surface, repair painting is required for the portion where the metal surface is exposed by the processing of the cutting guide groove. As measures for extending the tool life, JP-A-55-70434 and JP-A-57-
As seen in Japanese Patent No. 175034, a method of forming a cutting guide groove by composite extrusion molding has been proposed.
This known method was made on the premise of using a steel plate, and was an effective measure for extending the tool life,
Since the cross-sectional structure of the cutting guide groove is complicated, the conventional spray coating method has a drawback in that the paint does not spread to all the portions in the cutting guide groove and sufficient corrosion resistance cannot be obtained even if repair coating is performed.

[0006]

In the prior art using a sharp blade, aluminum is preferred as a material for its characteristics, and a material made of a steel plate is used only for extremely limited purposes. Is as described above. The main reasons are that the steel plate has a strong resistance to the sharp pressing force of the sharp blade, the tool life for machining is very short, the coating film on the steel plate surface is destroyed by machining, and the entire circumference of the cutting guide groove or the caulking part of the handle etc. On the other hand, there was a need for repair painting, and there was concern about corrosion resistance.

On the other hand, in response to the recent increase in awareness of global environmental problems, it is necessary to aim for products suitable for recycling. Even in metal cans, the can body and the can lid are made of the same material. In addition, the so-called "monometal can" has been emphasized. At present, most metal cans are made of steel plate, and they have excellent corrosion resistance.The easy-to-open steel plate lid has excellent corrosion resistance and does not require repair coating on the inner and outer surfaces.
It is eagerly awaited for the emergence of a productive method. Naturally, the steel sheet itself is highly economical, and it is expected that the steel sheet for both the can body and the can lid will be a more economical product that can be easily reused as a resource.

[0008]

The present invention has been made to solve the above problems all at once. The gist of the present invention is that the breaking elongation is 50 to 300% and the tensile elastic modulus is 6%.
Using a resin laminated steel sheet having a resin coating of 0 kg / mm ² or more and a thickness of 10 to 80 μm on both sides, the peripheral edge of the opening piece,
The inner and outer surfaces of the resin laminated steel sheet are characterized in that the cutting guide groove whose main constituent element is a thin-walled portion whose thickness at the thinnest portion is ½ or less of the thickness before processing is formed by composite extrusion. It is on the easy-to-repair can lid.

The present invention will be described in detail below. The steel plate used in the present invention has a plate thickness t ₀ : 0.150 to 0.300.
A material having a mechanical property of hardness ( _HR30T ) of 54 to 68 and elongation of 10 to 40% is used in the range of mm. On the surface of this steel sheet, Sn, Cr, Ni, Al,
One or more Zn metal plating is applied, and a resin film having excellent adhesion, workability, and corrosion resistance is laminated through a chromate-treated film to eliminate the need for repair coating after processing.

Specifically, the adhered amount is 0.5 to 3.0 g / m.
²Tin-plated steel sheet that has undergone chemical conversion treatment after tin-plating
0.3-2.0 g / m²Nickel plating after chemical conversion treatment
The applied nickel plated steel plate, Sn and Ni adhesion amount
0.5 to 2.0 g / m ², 0.01 to 0.5 g /
m²Sn plated with Ni and Sn in this order and then subjected to chemical conversion treatment
/ Ni plated steel plate, metal Cr adhesion amount 50-200 mg /
m², Oxide Cr5-30mg / m²Normal TFS (Ti
Kromku called n Free Steel)
For example, it is a steel sheet treated with romate.

A breaking elongation of 50 was measured on both surfaces of the surface-treated steel sheet.
~ 300%, tensile modulus 60kg / mm ² or more, thickness 1
The presence of a resin film of 0 to 80 μm is necessary. This resin film, when processing the cutting guide groove by composite extrusion molding,
Since it adheres well to the base material and the coating itself has excellent workability, it completely covers the base material even after processing, and it is an important factor that eliminates the need for conventional repair coating. Also, when opening the can, a specific resin is used to prevent the resin from locally remaining on the end face of the cutting guide groove (film remaining phenomenon, hereinafter referred to as feather) and impairing the appearance impression. There is a need.

As the physical properties of the resin film required for the present invention, it is important that the breaking elongation is in the range of 50 to 300%. If the elongation at break is less than 50%, a large number of defects will occur in the resin film due to insufficient elongation in forming the thin portion during the composite extrusion process described below, which is not preferable. On the other hand, if the elongation at break of the resin film exceeds 300%, a problem occurs when opening the can. That is, it is necessary to break the laminated resin film along the cutting guide groove at the time of opening the can. If the elongation is too high, the film stretches long before breaking, and a film residual phenomenon is likely to occur. It is necessary to keep the growth rate below. It is necessary that the elongation property satisfying both workability and feathering property is in the range of 50 to 300%, and more preferably in the range of 70 to 200%.

The elongation characteristics of the laminated resin film are measured by a method according to JIS C2318 after peeling the resin film from the base material. The second important point as the physical properties of the resin film is that the tensile modulus of elasticity is 60 kg / mm ² or more, more preferably 90
This is where a resin film having a tensile elastic modulus of at least kg / mm ² is required. The tensile modulus is the ratio of the tensile stress within the tensile proportional limit and the corresponding strain, and when there is no linear part in the stress-strain curve in the tensile test,
It is obtained from the slope of the tangent line at the deformation start point. This elastic modulus indicates the degree of hardness of the resin itself, and a material having a large elastic modulus is more elastic, and it is expected that excellent workability is imparted by keeping the strength difference with the base steel sheet small. . By adopting a resin film having a tensile elastic modulus of 60 kg / mm ² or more, more preferably 90 kg / mm ² or more, the resin film is scraped by the R part of the mold during the composite extrusion process, and build-up is performed. It is possible to effectively prevent flaws and the like in the friction portion with the mold, prevent the occurrence of film defects during processing, and open the way to non-repair of the inner and outer surfaces.

The laminated film thickness of the present invention is 10 to 10.
Although it is in the range of 80 μm, the range of 16 to 60 μm is particularly effective in consideration of the stability of performance and economy. Obviously, if the thickness is too thin, processing defects are likely to occur, but it is not necessary that the thickness be thick. 6
When the film thickness exceeds 0 μm, especially 80 μm or more, the corrosion resistance after processing progresses in a better direction, but when the cutting guide groove is broken (when the can is opened), the film stretches long before breaking and the film remains. It is disadvantageous to use an excessively thick film because the phenomenon easily occurs.

Specific examples of the resin film used include biaxially stretched polyester, biaxially stretched nylon, non-stretched polypropylene, biaxially stretched polypropylene and polyethylene. As a laminating method, the film itself is heat-bonded, or a thermosetting adhesive is applied and laminated on both surfaces of the steel plate described above. When the surface-treated steel sheet having the resin coating described in detail above is used to form an easily openable lid, the processing method is extremely important. That is,
The formation of the cutting guide groove by the pressing method of a sharp blade, which is a typical conventional technique, is not preferable because it also breaks the resin film and requires repair coating after molding. In order to form a cutting guide groove that ensures easy opening without breaking the resin film, it is important to extend the entire material by elongation deformation and form a thin wall part formed by a smooth plate thickness change. is there. At the peripheral edge of the opening piece, the thickness of the thinnest part is 1 / th of the thickness before processing.
By forming the cutting guide groove whose main constituent element is a thin portion having a thickness of 2 or less, it is possible to obtain a steel plate easy-open can lid that has excellent can openability and does not require repair coating on the inner and outer surfaces.

As a concrete processing method, an upper die and a lower die which substantially correspond to the shape and size of the opening piece are used to press the essential parts of the lid main body so that the portion corresponding to the opening piece shape is moved upward or downward. Extrude. At this time, the peripheral edge portion of the opening piece is stretched between the upper and lower molds so as to reach a desired thickness, thereby forming a thin portion having a smooth change in plate thickness. The thickness of the thinnest part needs to be 1/2 or less of the thickness before processing from the viewpoint of can openability.

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

In these series of processing steps, the resin film having the above-mentioned characteristics is uniformly stretched together with the base material, and no processing defects occur. Therefore, repair coating after processing is not required and good corrosion resistance is ensured. You can Further, since the press working such as extrusion or push back is the basic work, there is no problem of tool life seen in the pressing method of the sharp blade, and excellent productivity is guaranteed.

The present invention is mainly characterized by optimizing the cutting guide groove existing in the peripheral portion of the opening piece. The tear-off method in which the handle and the opening piece are torn off to separate from the main body of the can, and the handle and the opening. It is possible to apply both of the Stein-tab type methods in which both pieces remain fixed to the can body after opening the can.

[0020]

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

When a steel sheet having a biaxially oriented polypropylene resin film on both sides is used to form an easy-opening can lid as shown in FIG. 1, as shown in FIG. , 6 were used to press the essential parts of the lid main body to extrude the portion corresponding to the opening piece 2 upward. At this time, the peripheral edge portion of the opening piece 2, the lid body 1 and the connecting piece 7 were processed so as to form a thin portion which is downwardly expanded and inclined, and which has a smooth plate thickness change due to extension. Then, as shown in FIG. 3, the opening main body 2 is placed on the lower mold 9 having the recessed groove 8 in the portion corresponding to the peripheral portion of the opening piece 2 so that the opening piece 2 comes to the inside of the recessed groove 8. 1 was placed and pressed by the upper mold 10 having a flat lower surface.

By this operation, the connecting piece 7 having a gradual change in plate thickness is bent downward from the approximate middle portion into a V-shape and protrudes into the recessed groove 8. Thus, a thin cutting guide groove 4 having a V-shaped cross section is formed in the peripheral edge of the opening piece 2 on the upper surface of the lid body 1. The thus-formed easy-open can lid was subjected to an evaluation of the can openability by measuring the tearing force of the opening piece and an electric test for examining the degree of destruction of the resin film on the inside and outside of the can. The openability of the molded product (the force to pull up the handle and the force to tear off the opening piece) is 2.0k.
It was excellent as g or less, and the resin coating had an electric current of about 0.3 mA and was excellent in soundness, which satisfied the target. Further, no visually noticeable feather was observed around the cut edge of the cut guide groove.

Example 2 A two-layer structure polyester resin film having different melting points was used on the same plated steel sheet as in Example 1, and a low melting point resin was heat-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 using the steel plates having polyester resin coatings on both sides to prepare an easy-open can lid as shown in FIG. 1, as shown in FIG. 4 (a), upper and lower molds corresponding to the shape and size of the opening piece are formed. A portion corresponding to the opening piece 2 was extruded downward with 5 and 6. At this time, the peripheral edge portion of the opening piece 2, the lid body 1 and the connecting piece 7 are formed so as to form a thin wall portion which is inclined upward and spread and which has a smooth change in plate thickness due to extension. At the same time, a biting groove 16 is attached to the peripheral portion of the lower surface thereof, and then the opening piece is pressed upward, whereby a thin portion having a gentle change in plate thickness is V-shaped upward (FIG. 4 (b)). ) Was bent to form a cutting guide groove.
The presence of the bite groove 16 is intended to improve the can openability by forming a remarkably thin portion between the cutting guide groove 4 and the bite 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 also formed similarly to the steel plate, and the film thickness remaining on the surface of the thinnest part was about 6 μm.

The can openability of the molded product was 1.8 kg or less and the product was opened without problems, and the energization value of the resin film was 0.8 on the inner surface side.
mA and 0.9 mA on the outer surface side were sufficiently satisfactory for practical use. Further, no visually noticeable feather was observed around the cut edge of the cut guide groove. Example 3 Plate thickness 0.180 mm, hardness ( _HR30T ) 64, elongation 24%
A nickel plate having an adhered amount of 0.58 g / m ² was plated on both surfaces of the steel sheet having C., and a chromate treatment consisting of metal chromium 5 mg / m ² and hydrated chromium oxide 12 mg / m ² (as Cr) was performed. After washing with water and drying, this steel plate was heated to laminate a 40 μm biaxially stretched nylon film with a thermosetting epoxy adhesive. This nylon film had an elongation of 90% and a tensile elastic modulus of 130 kg / mm ² .

The steel sheet having a biaxially stretched nylon resin coating on both sides was processed by the same processing method as in Example 2 so that the thinnest portion had a steel sheet thickness of 50 μm. The resin film is also formed like a steel plate, and the film thickness remaining on the surface of the thinnest part is about 11
was μm. The can openability of the molded product is 1.6 kg or less and the product can be opened without problems, and the energization value of the resin film is 0.
The values of 1 mA and 0.08 mA on the outer surface side were sufficiently satisfactory for practical use. Further, no visually noticeable feather was observed around the cut edge of the cut guide groove.

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

Using this steel plate as a 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 the important parts of the lid body with the upper and lower molds corresponding to the shape and size of the opening piece, the mold corner R
The phenomenon that the resin film was scraped off on the part and the resin built up was observed. The molded product's can openability (the force to pull up the handle and the force to tear off the opening piece) is excellent at 2.0 kg or less, and the amount of electricity applied to the resin film is about 1.5 mA, which is judged to be practical in terms of corrosion resistance However, the film remained severely around the cut edge of the cutting guide groove that was broken at the time of opening, giving an unpleasant appearance and leaving a problem in practicality.

Comparative Example 2 On the same plated steel sheet as in Example 1, a polystyrene film having a thickness of 40 μm was laminated via a thermosetting epoxy adhesive. This film had an elongation at break of 40% and a tensile elastic modulus of 120 kg / mm ² . When this steel sheet was processed in the same manner as in Example 2, the energization value of the resin film was 540 mA, which was a very large value, and many defects were found in the resin film inside the cutting guide groove. It was not there.

[0030]

As described above, in the easy-open can lid according to the present invention, the raw material and the processing method are specified, that is, the resin film having the characteristics matching the processing method of the present invention and the composite extrusion without using the sharp blade. It is constructed by adopting a processing method. Therefore, it is possible to completely eliminate the problems of the tool life for machining, the problem of requiring repair coating, and the anxiety in terms of corrosion resistance, which were the major problems of the prior art.

If a steel plate easy-open can lid is put into practical use, it will be possible to make it into a "monometal can", so that it is possible to provide the market with products suitable for recycling in response to recent global environmental problems. Is. Naturally, the steel sheet itself is highly economical, and it is expected that the steel sheet for both the can body and the can lid will be a more economical product that can be easily reused as a resource.

[Brief description of drawings]

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

FIG. 2 is a vertical cross-sectional view showing the procedure of the present invention in process order.

FIG. 3 is a vertical cross-sectional view showing the procedure of the present invention in process order.

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

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

[Explanation of symbols]

 1 Lid body 2 Opening piece 4 Cutting guide groove 5 Upper mold 6 Lower mold 7 Continuous piece 8 Recessed groove 9 Lower mold 10 Upper mold 16 Biting groove

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Keiji Taniuchi 2-6-7 Nishikojiya, Ota-ku, Tokyo Inside Tanikei Manufacturing Co., Ltd.

Claims (1)

[Claims] 1. A breaking elongation of 50 to 300% and a tensile modulus of elasticity of 6.
Using a resin laminated steel sheet having a resin coating of 0 kg / mm ² or more and a thickness of 10 to 80 μm on both sides, the peripheral edge of the opening piece,
The inner and outer surfaces of the resin laminated steel sheet are characterized in that the cutting guide groove whose main constituent element is a thin-walled portion whose thickness at the thinnest portion is ½ or less of the thickness before processing is formed by composite extrusion. Easy to repair can open lid.