JP2000190964A - Easily unsealable can lid and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an easily unsealable can lid useful for application to a can lid for a can to be filled with foodstuffs, beverages, etc., by surely controlling the contact of a cut end face at an opening portion of the can with contents, and provide the manufacture of the can lid, capable of simplifying and reducing manufacturing processes, having high productivity, and reducing the manufacturing cost of the can lid. SOLUTION: An easily unsealable can lid is composed of an easily peelable tape sealing material 8 allowed to adhere to the outer face side of a panel sheet 2 having coated film layers 2a, 2b formed on both faces thereof, respectively, and having holes defined in advance, in such a manner as to cover the holes from above the coated film layers 2a, 2b and to closely contact with the surrounding parts of the holes. In this can lid, the innermost layer of the tape sealing material 8 is made up of a PP film 8e having thermally adhesive properties, and is so formed that the PP film 8e covers the cutting end faces 7 of the holes and covers even the coated film layer 2b on the inner face side of the panel sheet 2 at the surrounding part of each hole to be allowed to adhere to the coated film layer 2b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easy-to-open can in which a previously opened opening of a metal can lid is closed with a tape (opening piece) provided with a thermoplastic resin layer on at least the surface of the metal can lid. Regarding the lid.

[0002]

2. Description of the Related Art An opening piece which covers a previously opened opening of a metal can lid with an opening piece and a peripheral portion of which has at least a surface of the tape on the metal can lid side made of a heat-welding resin. It is well known that a can lid that can be easily opened by heat welding is known, for example, from JP-B-56-43940.
JP (hereinafter referred to as Conventional Example 1), JP-A-59-93639 (hereinafter referred to as Conventional Example 2), JP-A-59-93640 (hereinafter referred to as Conventional Example 3), and JP-B-60-42101 ( Hereinafter, it is disclosed in Conventional Example 4).

[0003] In Conventional Example 1, an opening provided in a can lid has a large number of small holes, and a film or tape having a thermo-adhesive thermoplastic resin layer covering and closing these openings is provided. An easy-open can lid having a projection in which the opening piece is fitted in these small holes is disclosed.

[0004] Further, the prior art 2 protects the cut end face of the opening provided in the can lid, does not peel off even when subjected to pressure-resistant adhesion between the periphery of the opening and the unsealing piece and a drop impact of the can. In order to obtain an easy-to-open can lid with good adhesiveness, the cut end surface of the opening is covered with a thermoplastic resin in a U-shaped cross section to protect it. This prevents the metal of the can lid from being eroded by the liquid to dissolve in the content liquid), and also bonding the unsealing piece through the thermoplastic resin coating having a U-shaped cross section. .

[0005] Further, the prior art 3 discloses an invention for the same purpose as the above-mentioned prior art 2, but FIGS. 4 and 6 cover the opening and are provided in advance around the opening. An opening piece that is thermally bonded to the adhesive layer that is provided, and a peripheral portion thereof is adhered to the periphery of the opening opposite to the adhesive surface of the opening piece, and the center portion is fitted into the opening and the opening piece. An easy-open can lid provided with a protective resin layer made of a pressure-sensitive adhesive that is adhered to the cover is disclosed.

In addition, the publication of Conventional Example 4 discloses an easy-open can lid in which most of the cut edges of the opening of the lid member are covered with a thermoplastic resin or a resin composition.

[0007]

First, the easy-open can lid described in the prior art 1 is corroded by the liquid contained in the can because the cut end surface of the opening is not covered with resin or the like. In addition, since the metal of the can lid may dissolve in the content liquid and change the taste of the content liquid, it cannot be used as a can lid for filling foods, beverages, and the like that may corrode the can lid.

Next, in the easy-to-open can lid disclosed in Conventional Example 2, after the cut end surface of the opening is covered with a thermoplastic resin having a U-shaped cross section, an opening piece is welded to the coated resin. , From the cut end of the opening metal dissolves in the content liquid,
Although the cut end does not corrode, it is complicated and multi-step (thermoplastic resin film bonding process with opening to the inside and outside of the can lid, pressing process into the opening of the resin film, thermal bonding of the opening piece to the outside of the can lid) Step) of covering the cut end face of the opening with a thermoplastic resin in a U-shaped cross section is required, and the manufacturing process is complicated and multi-step, resulting in an increase in the manufacturing cost of the can lid. is there.

Further, the easy-to-open can lid described in Conventional Example 3 is
Although it is excellent in preventing corrosion of the cut end surface of the opening and elution of the metal of the can lid into the content liquid, after bonding a thermal adhesive layer around the opening, the opening piece is bonded to this adhesive layer. In order to include a step of heat bonding and then bonding a film made of a sticky adhesive to the surface on the opposite side of the opening and projecting the center part of the film to the opening, and bonding the film to the unsealing piece, the method also requires multiple steps. It is a process, and there is a problem that productivity is poor and the manufacturing cost of the can lid increases.

[0010] Further, the easy-open can lid described in Conventional Example 4 is
Since a step of covering the cut end surface of the opening with a thermoplastic resin and a step of heat-bonding the opened piece to the coated resin are required, the cans described in the above two patent publications (conventional examples 2 and 3). Although it is not as good as the lid, the production process is still many and the production cost of the can lid is high. Also, like the can lid described in Conventional Example 2, the can lid is coated in a U-shaped cross section with a thermoplastic resin. Instead, only the part that is flush with the cut end face is covered with thermoplastic resin, so the impact of transporting the can lid during can manufacturing and can manufacturing causes the coating on the metal surface to There is a risk of peeling off from the joint with the resin layer, the penetration of the canned contents liquid from this joint, causing peeling, and corrosion of the metal.

The present invention solves the above-mentioned problems of the prior art, that is, by reliably suppressing the contact between the cut end surface of the opening and the contents, the can lid of a can filled with foods and beverages. An object of the present invention is to provide an easy-to-open can lid useful for application to a container. It is another object of the present invention to provide a method for manufacturing an easily-openable can lid that has simple and few steps, has good productivity, and can be manufactured at low cost.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a first aspect of the present invention is to provide a metal film having a coating film layer formed on both sides and a pre-formed opening. An easy-open can lid comprising a can lid and an easy-to-peel-off opening piece that covers the opening on the outer surface side of the can lid and adheres so as to be in close contact with the periphery of the opening. The opening piece is formed at least on the side facing the outer surface side of the can lid from a thermo-adhesive thermoplastic resin layer, and the thermoplastic resin layer covers the cut end surface of the opening,
In addition, the coating film layer on the inner surface side of the can lid around the opening is also covered, and is adhered to the coating film layer on the inner surface side of the can lid. In the invention according to claim 1, the thermoplastic resin layer constituting the opening piece not only thermally adheres to the coating film layer on the outer surface of the can lid around the opening, but also covers the cut end surface of the opening, Furthermore, the coating film layer on the inner side of the can lid at the periphery of the opening is covered and is thermally bonded to this coating film surface, so that the cut end surface of the opening is completely covered, and the can manufacturing process and the canning manufacturing process are completed. It does not peel off due to impact during transportation. Therefore, the cut end face of the opening of the can lid is not corroded by the solution in the can, and the metal of the can lid is not eluted in the can content liquid, thereby deteriorating the taste, color, aroma, etc. of the content liquid.

According to a second aspect of the present invention, in the easy-open can lid according to the first aspect, the thermoplastic resin layer portion covering the coating film layer on the inner surface side of the can lid has at least a peripheral portion thereof. Is characterized in that it becomes thinner as the distance from the opening increases.

According to the second aspect of the present invention, the portion of the thermoplastic resin layer covering the coating film layer on the inner surface side of the can lid becomes thinner at least at the peripheral portion as the distance from the opening increases. Even when other can lids or machine parts come into contact with the periphery of the opening on the inner side of the can lid when stacking the can lid, transporting the can lid, manufacturing cans, etc., it covers the periphery of the opening on the inner surface side of the can lid. Since the applied thermoplastic resin layer is not subjected to a force in the direction of peeling from the coating film surface, this portion does not peel.

[0015] The third aspect of the present invention is the first or second aspect.
In the easy-open can lid according to the above, the coating film layer formed on both sides of the metal plate is formed by painting and baking a paint in which a modified polyolefin resin powder is dispersed in a thermosetting resin solution. The heat-adhesive thermoplastic resin layer on the side of the opening piece facing the outer surface of the can lid is made of a polyolefin resin. According to the third aspect of the present invention, the coating film layer on the outer surface side of the can lid and the inner surface side of the can lid which are thermally bonded to the polyolefin resin layer constituting the opening piece are formed from a coating material in which a modified polyolefin resin powder is dispersed. Therefore, at the interface that was heat-bonded, the polyolefin-based resin and the modified polyolefin-based resin with improved adhesion were partially bonded,
The adhesive strength between the thermosetting resin coating film and the polyolefin resin is stronger than that of the ordinary resin, so it is difficult to peel off. Will be excellent.

According to a fourth aspect of the present invention, a can lid having an opening formed by punching an opening having a predetermined shape is formed from a metal plate coated on both sides, and the can lid is attached to the can lid. The number of openings provided is the same as the number of openings provided, and a projection having a diameter slightly smaller than the size of each opening is provided, and an annular depression is formed in a peripheral portion of the projection, and It is heated by placing it on a heated mold, and the thermoplastic resin layer side of an opening piece, at least one side of which is formed of a thermo-adhesive thermoplastic resin layer, is placed on the outer surface side of the can lid. Is placed facing the periphery of the opening, and then the opening piece on the side opposite to the thermoplastic resin layer is pressed by a heated pressing plate, so that the thermoplastic resin of the opening piece The layer is thermally bonded to the periphery of the opening on the outer surface side of the can lid, and the portion corresponding to the opening is removed. A resin of thermoplastic resin layer is softened and deformed, it is easy open can lid manufacturing method, characterized in that for covering an opening peripheral portion of the cutting edge and the can lid inner surface side of the opening by the resin.

In the invention according to claim 4, the resin covering the cut end surface of the opening is a thermo-adhesive thermoplastic resin constituting an opening piece on the side facing the outer surface of the can lid. When thermally bonding to the periphery of the opening on the outer surface of the lid, the heat is used to soften and deform the thermoplastic resin, and the softened resin is
Extruded into the gap between each opening and each projection, and further pushed into the depression, it is possible to cover the cut end face of the opening and the inner surface of the can lid, so the processing process does not increase so much Therefore, it does not significantly increase the cost of manufacturing the can lid.

[0018]

Embodiments of the present invention will be described below.

In FIG. 1 to FIG. 3, an easy-open can lid 1 having a panel plate 2 in the center portion is made of a metal such as an aluminum alloy material or a steel material (tin-plated steel plate, nickel-plated steel plate, electrolytic chromic acid-treated steel plate). The coating film layers 2a and 2b are formed on both sides, and the flange portion 6 provided on the outer periphery of the panel plate 2 is usually double-wound with the can body to be used as a beverage can. An annular groove 5 is formed on the outer periphery of the panel plate 2, and a large number of small discharge holes 3 (openings) are formed on the panel plate 2 near the annular groove 5, and the one shown in FIG. But can be in various forms. Also,
A vent hole 4 (opening) is provided on the side opposite to the center of the lid of the pouring hole 3. However, the vent hole 4 may be omitted, but when the diameter of the pouring hole 3 is extremely small, it is desirable to add it in consideration of the outflow time of the contents. The pouring hole 3 is
In FIG. 1, it is arranged circularly with one hole 3 as a center, and forms an opening 3a for pouring as a whole.

Next, the tape sealing material 8 will be described. A tape sealing material 8 (opening piece) covers the pouring opening 3a and the ventilation hole 4 from above the coating film layer 2a on the outer surface side of the panel plate 2, and a peripheral portion of the opening 3a, 4. It is an easily peelable member that is thermally bonded so as to be in close contact with.
FIGS. 3 and 4 show an example of the configuration of the tape sealing material 8.
As shown in the figure, the outermost layer includes a PET film 8a having a thickness of about 25 μm, a printing layer 8b having a thickness of about 2 μm (a printing ink layer and a primer layer thereunder), an aluminum foil 8c having a thickness of about 25 μm, About 1 μm primer layer 8d
(Adhesive layer) and the innermost layer has a thickness of about 130 μm
The polypropylene film 8e (PP film) was used. First, the PET film 8a was used for covering the aluminum foil 8c. For example, as an example, a biaxially stretched espet film T-4100 manufactured by Toyobo
And the like. Although the lower printed layer 8b may be omitted, it can be used for instructing an opening method or by giving an advertisement, thereby providing a can lid with high advertising effect. For example, as the printing ink, one that conforms to the “Self-regulation on printing ink for food packaging materials” of the Printing Ink Industry Association and the Printing Ink Varnish Industry Association is used. In addition, a pigment is used as a coloring agent. Further, the lower aluminum foil 8c is used because it has no gas permeability and a required strength is obtained. However, a film having low gas permeability may be used instead of the aluminum foil 8c. For example, regarding aluminum foil 8c, A1N30H of JIS-H4160
-O (99.3% aluminum soft foil). The lower layer is made of aluminum foil 8
As a primer layer 8d for bonding the c and the innermost PP film 8e, an olefin monomer such as ethylene, propylene, and butene and an ethylenically unsaturated carboxylic acid such as maleic acid, maleic anhydride, and acrylic acid are used. Modified polyolefin that has been copolymerized, or a modified polyolefin obtained by graft-polymerizing an ethylenically unsaturated carboxylic acid or an anhydride thereof to a polyolefin such as polyethylene, polypropylene, or polybutene, or a resin powder mainly composed of these modified polyolefins. (Preferably 0.1
(A powder having a particle size of about 50 μm) dispersed in a solvent, for example, Unistor R- manufactured by Mitsui Chemicals, which is a hydrocarbon solvent dispersion of non-chlorine modified polypropylene.
100K and the like. Finally, the innermost layer of the polypropylene film 8e is safe for food hygiene, excellent in heat resistance, strong in film strength even after retort treatment, and has an impact strength,
An unstretched PP film having improved low-temperature impact resistance and excellent oil resistance, chemical resistance, and water resistance was used. For example, TOCELLO CP film RXC-11 manufactured by TOCELLO can be used.

Each of the pouring holes 3 and the vent holes 4 is provided with a cut end face 7.
(See FIG. 3), but when the panel plate 2 is made of metal, the cut end surface 7 is coated to prevent corrosion of the panel plate 2 and flavor contamination of the contents in the can. That is, usually, the panel plate 2 is coated with a protective paint or the like on the inner surface of the lid so that the metal does not come into direct contact with the contents after molding,
The outer surface of the lid is similarly covered with a protective paint or the like. Such a coating process is usually in a state of a strip-shaped metal plate (or a flat plate cut to a predetermined size) before forming a lid,
The same applies to the present invention, and the coating film layers 2a, 2b
Is formed. Therefore, each pouring hole 3 and the vent hole 4 are also drilled after being covered with the coating layers 2a and 2b of the protective paint. This is because the cover is formed after the lid is formed and the holes 3 and 4 are opened, because the production method is different from the current one, new equipment is required, the running cost is increased, and it is not economical. Further, it is difficult to cover the cut end face of the small hole without leakage, and expensive equipment is required.

Next, the protective coating on the outer and inner surfaces of the panel plate 2 will be described. As an example of the protective paint, an epoxy-phenol resin paint or an epoxy-urea resin paint (epoxy-amino resin paint, epoxy-acrylic resin, amino In the present invention, carbonized non-chlorine-modified polypropylene, which is a primer used in bonding the aluminum foil 8c of the tape seal material 8 to the PP film 8e, may be used. Hydrogen solvent dispersion,
On the outer surface of the lid, 5 to 25 wt% of the epoxy-urea resin coating solution is mixed and applied, and on the inner surface of the lid, the epoxy-phenolic resin is applied. The coating solution is mixed and applied at a rate of 15 to 25% by weight. In addition, not only the modified polypropylene (modified polyolefin) powder but also the polypropylene (polyolefin) powder may be dispersed in the dispersion (dispersion liquid) mixed with the coating solution. In addition, about application amount,
The application amount was almost the same as that of the current SOT lid. For example, the outer surface coating amount is 40 to 60 mg / dm2, and the inner surface coating amount is 100
１２０120 mg / dm2. The coating film in which the primer was mixed was a low peel strength type, ie, PP film 8
e and the panel plate 2 to provide a strong bond, but in order to open the pouring hole 3 and the vent hole 4 in order for the consumer to drink the contents liquid, the panel portion around these holes is used. When the tape sealing material 8 is to be peeled, it is desirable that the tape sealing material 8 can be easily peeled from the panel plate 2.
From that viewpoint, the solid content of the modified polypropylene in the coating film is preferably 0.1 to 8 wt%. In the present embodiment, the aluminum foil 8c of the tape sealing material 8 is used.
Is bonded to the PP film 8e with a primer (PP) mixed with a thermosetting resin coating solution for thermal bonding between the PP film 8e of the tape sealing material 8 and the panel plate 2.
The same primer was used alone as in the case where a modified polypropylene powder having good heat adhesion to the film was dispersed in a solvent.
The bonding between the PP film 8e and the tape sealing material 8
Is required to be stronger than the bond between the PP film 8e and the panel plate 2. If not, the tape sealing material 8 may peel off between the aluminum foil 8c and the PP film 8e when peeling off.

Then, the tape sealing material 8 is adhered to the panel plate 2 by the heat seal molding described below, so that the PP film layer 8e is cut off at the cut end face of each of the pouring holes 3 and the vent holes 4 as shown in FIG. 7 and the coating film layer 2b on the inner surface side of the panel plate 2 around each of the pouring holes 3 and the ventilation holes 4 (inner coating portion 8e ').
Is adhered to the coating film layer 2b on the inner surface side.

Next, a method of manufacturing the easy-open can lid 1 will be described.

FIG. 5 is a schematic view showing a method of manufacturing the easily-openable can lid 1. First, before the heat seal molding shown in FIG.
The panel plate 2 on which the tape sealing material 8 is placed (preferably, the flange portion 6 is preferably formed on the outer periphery in advance) is placed on the heated lower mold 10. The shape of the lower mold 10 is smaller than the diameter of each of the pouring holes 3 and the ventilation holes 4 (for example, when the diameter of the hole is 5.5 mm, the diameter is 4.8 mm) and the height is a panel. Protrusions 12 having substantially the same thickness as the plate 2 are provided so as to correspond to all the pouring holes 3 and the vent holes 4 (the center of each protruding portion 12 and the center of each of the pouring holes 3 and the vent holes 4). When the panel plate 2 is placed on the lower mold 10 around each convex portion 12, the diameter is slightly larger than the diameter of each hole 3, 4 (for example, the diameter of the hole). Is 5.5 mm, the diameter is 6.2 mm.), And the deepest portion has a depth of 0.05 ± 0.02 mm in the form of an annular recessed portion 13.
Moreover, it is desirable that each annular concave portion 13 has an inclined surface that becomes gradually shallower from the center of the convex portion 12 toward the outer peripheral portion at least in the outer peripheral portion. The reason why the depth of the deepest portion was set to 0.05 ± 0.02 mm is that the thickness of the thermoplastic resin layer thermally bonded to the inner surface of the can lid around each of the holes 3 and 4 (this The thickness of the thermoplastic resin layer on the inner surface side of the can lid is smaller than the value in this range (the thickness of the deepest portion of the annular recess 13). If the depth is shallower than the value in this range), the coating on the edge of the cut end face of each hole 3, 4 is too thin, and the performance of preventing corrosion by the content liquid is reduced. It is difficult for the thermoplastic resin layer (PP film) of the tape sealing material 8 melted by heat at the time of heat sealing with the sealing material 8 to flow into the annular recessed portion 13, so that the cut end face is covered and the can lid inner surface is thermally bonded. If the thickness of the thickest part is thicker than this range,
This is because feathering occurs when the tape seal material 8 is peeled off. In addition, the provision of the annular recessed portion 13 having the above structure surrounding the convex portion 12 allows the tape sealing material 8 to be formed.
The innermost PP film layer 8e of the tape sealing material 8, which has been melted by the heat of the heat bonding, easily flows to the inner surface side of the panel plate 2, and completely covers the cut end faces of the holes 3, 4. A portion on the inner surface side of the can lid around each of the holes 3 and 4 can be covered.

Next, as shown in FIG. 5B, pressure is applied to the tape sealing material 8 by using a heated pressurizing upper mold 11.
Is heat-seal-molded to the panel plate 2, the innermost PP film 8e of the tape sealing material 8 is allowed to flow to the inner surface side of the panel plate 2, and the cut end face 7 of each hole is set to the PP film 8e.
To cover. In this heat seal molding, the upper mold 1
1 is attached to a device to which pressure is applied, such as a press. On the other hand, a heated lower mold 10 is arranged below the panel plate 2. The shape of the upper mold 11 is provided with a step in the thickness direction so that only the periphery of each of the holes 3 and 4 can be pressed strongly. The reason is that, when the entire surface is flat, according to the method of the present invention, in order to extrude the PP film 8e into the groove of the lower mold 10, the peel strength between the tape sealing material 8 and the panel plate 2 other than the holes 3 and 4 is required. Is too high, which is not desirable. In addition, it facilitates the flow of the innermost PP film 8e of the tape seal material 8 along the shape of the annular recess 13 of the lower mold 10, and also reduces the PP. Another reason is that the film 8e is economical because the film 8e can be made thinner than when it is entirely flat.

As a result, as shown in FIG. 5B, the cut end faces 7 of the holes 3 and 4 can be covered with the PP film 8e. In addition, in the case of this manufacturing method, not only the covering of the cut end faces 7 of the holes 3 and 4 but also the inner surface of the panel plate 2 can be covered.
By the way, as described above, since the holes 3 and 4 were opened after coating on the metal plate of the panel plate 2, the cut end face 7 had poor adhesion to the tape sealing material 8 at the holes 3 and 4 where the metal surface was exposed. The outer and inner surfaces of the panel plate 2 are coated with a thermosetting resin paint containing a thermoplastic resin (PP film) in the innermost layer of the tape seal material 8 and a primer (modified polypropylene) having high adhesiveness dispersed therein. The outer surface of the panel plate 2 and the innermost layer of the tape sealing material 8 and the inner surface of the panel plate 2 and the innermost layer of the tape sealing material 8 are bonded and bonded by primer (modified polypropylene) particles and thermoplastic resin (polypropylene), respectively. That is, there is no possibility that the coating on the cut end face 7 existing between the two may be peeled off. Further, since the cut end face 7 covered with the innermost layer of the tape sealing material 8 does not come into direct contact with the content liquid, the content liquid is safe. Furthermore, not only the number of processing steps for covering the cut end faces of the holes 3 and 4 is small, but also the material cost is small, so that it is economical.

Next, with reference to FIGS. 6, 7 and 8, how the manufacturing method of the above easy-open can lid 1 is applied to manufacture of a can lid in an actual mass production system will be described.

First, in the basic end molding step, generally, a substantially circular disk punching molding from a strip-shaped metal plate or a flat plate, an annular groove 5 molding, and a flange portion 6 around the lid are formed by press molding. In the present embodiment, the normal S
Basic end molding is performed using the same manufacturing equipment as the OT lid manufacturing equipment. In the subsequent steps, molding is performed using another press while intermittently moving.

In the end piercing step, each of the pouring holes 3 and the vent holes 4 are formed by punching.

In the preheating step, the panel panel 2 having a basic end that has undergone the end piercing step is heated by being sandwiched between the heated upper and lower molds.

In the seal cutting and pre-sealing step, a part (a part corresponding to a lifting part) is punched out of a sealing material formed in advance in a predetermined shape into a required shape, and a set position for closing each of the pouring holes 3 and the ventilation holes 4. The tape sealing material 8 punched out is adhered. The reason why the raised portion of the sealing material is formed by embossing is to make it easier to lift up (to make it less slippery when picking with a finger and applying force). As shown in FIG. 6, the basic end and the seal material in this step are obtained by intermittently moving the circular basic end having the coating layers 2a and 2b in one direction, and cutting and sealing the seal end. At the pre-seal process position, the sealing material is intermittently moved in a direction orthogonal to the plate material.
In addition, a belt, a slide bar, a turret method, or the like is adopted as a feed method for a can lid (basic end). The feed method of the sealing material is coil feed, and scrap (skeleton) is wound.

In the heat sealing step, as described above, pressure is applied using the heated lower mold 10 and upper mold 11 so that the cut end faces 7 of the holes 3 and 4 and the panel around the holes 3 and 4 are pressed. The inner surface of the plate 2 is covered with the PP film 8e. Note that the preheating step and the heat sealing step may be one step, but the number of steps may be increased to increase the number of steps to increase the speed.

FIGS. 7 and 8 show a seal cutting and pre-sealing apparatus arranged in the seal cutting and pre-sealing step. 7 and 8, 20 is a can lid, 21 is a sealing material,
22 is a lower mold, 23 is a punch cutter, 24 is a bush (ceramic), 25 is a bush holder, 26 is a punch stripper, 27 is a die cutter, 28 is a first coil spring, 29 is a second coil spring, and 30 is a stripper push. The pin 31 is a third coil spring. The lower mold 22 has a flat upper surface in the pre-sealing step, and is provided with a heater and a thermocouple (for temperature control). In the above embodiment, since polypropylene having excellent heat resistance was used as the thermoplastic resin of the innermost layer of the tape sealing material, modified polypropylene powder was mixed in the paint applied to the inner and outer surfaces of the can lid. However, in the case of a can that does not require high heat resistance, as the thermoplastic resin of the innermost layer of the tape sealing material, for example, polyethylene can be used, in which case it is mixed in the paint applied to the inner and outer surfaces of the can lid Needless to say, as the thermoplastic resin powder, modified polyethylene or a mixture of modified polyethylene and polyethylene is preferable to modified polypropylene.

[0035]

According to the first aspect of the present invention, a metal can lid having a coating film layer formed on both surfaces thereof and having an opening formed in advance, and a metal can lid provided on the outer surface side of the can lid. An easy-to-open can lid comprising an easy-to-peel-off opening piece that covers the opening from above the paint film layer and is adhered so as to be in close contact with the periphery of the opening, wherein the opening piece has at least an outer surface side of the can lid. The facing side is formed from a thermo-adhesive thermoplastic resin layer, the thermoplastic resin layer covers the cut end surface of the opening, and a coating film layer on the inner side of the can lid around the opening. And can adhere to the coating film layer on the inner surface side of the can lid, so that contact between the cut end surface of the opening and the contents is reliably suppressed, so that cans for filling foods, beverages, etc. The effect of being able to provide an easy-to-open can lid useful for application to the lid is obtained.

According to the second aspect of the present invention, there is provided the first aspect.
In the easy-open can lid according to the, the thermoplastic resin layer portion covering the coating film layer on the can lid inner surface side, at least in the peripheral portion, because it becomes thinner away from the opening, In addition to the effects of claim 1, even when other can lids or mechanical parts contact the can lid inner surface side opening peripheral portion at the time of can lid stacking or can lid transportation and can manufacturing, etc.
This has the effect of providing an easy-open can lid in which this portion does not peel off.

In the invention according to claim 3, claim 1 is
Or in the easy-open can lid according to 2, wherein the coating layer formed on both surfaces of the metal can lid is formed by coating and baking a paint obtained by dispersing a modified polyolefin-based resin powder in a thermosetting resin solution. The thermo-adhesive thermoplastic resin layer on the side of the opening piece facing the outer surface of the can lid is made of a polyolefin-based resin. , When opening the opening piece,
An appropriate peeling easiness can be obtained, and the effect of having a high cut end face covering property before peeling the opened piece can be obtained.

According to the present invention, a can lid having an opening formed by punching an opening having a predetermined shape is formed from a metal plate having both sides coated. The number of openings provided in the lid is the same as the number of openings, and the projections have a slightly smaller diameter than the size of each opening, and an annular depression is formed around the projection. Heating by placing on a pre-heated mold, at least one side of the opening portion of the thermoplastic resin layer side of the thermoplastic resin layer of the thermo-adhesive thermoplastic resin layer, the can lid of the It is placed in a state facing the periphery of the opening on the outer surface side, and then the opening piece on the side opposite to the thermoplastic resin layer is pressed by a heated pressing plate, so that the heat of the opening piece is A plastic resin layer is thermally bonded to the periphery of the opening on the outer surface side of the can lid, and a portion corresponding to the opening is formed. Since the resin of the thermoplastic resin layer is softened and deformed, and the resin is used to cover the cut end face of the opening and the periphery of the opening on the inner surface side of the can lid, the process is simple and less, and good productivity and The effect of being able to provide a method of manufacturing a can lid that is easy to open and that can be manufactured at low cost is obtained.

[Brief description of the drawings]

FIG. 1 is a plan view showing an easy-open can lid according to an embodiment of the present invention.

FIG. 2 is a bottom view showing the easy-open can lid according to the embodiment of the present invention.

FIG. 3 is an enlarged sectional view of a hole of the easy-open can lid according to the embodiment of the present invention.

FIG. 4 is a view showing a configuration of a tape sealing material of the easily-openable can lid according to the embodiment of the present invention.

FIG. 5 is a schematic view showing a method (heat-sealing step) of manufacturing the easily-openable can lid according to the embodiment of the present invention.

FIG. 6 is a process chart in a case where the method for manufacturing an easily-openable can lid according to the embodiment of the present invention is applied to an actual can lid manufacturing line.

FIG. 7 is a view showing a seal cutting and pre-sealing apparatus for opening a mold used in a seal cutting and pre-sealing step of the method for manufacturing an easy-open can lid according to the embodiment of the present invention.

FIG. 8 is a view showing a seal cutting and pre-sealing apparatus at the time of shutting a mold used in a seal cutting and pre-sealing step of the method for manufacturing an easy-open can lid according to the embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 can lid 2 panel plate 2 a, 2 b coating layer 3 pouring hole 4 vent hole 5 annular groove 6 flange portion 7 cut end face 8 tape seal material 8 a PET film 8 b printing layer 8 c aluminum foil 8 d primer layer 8 e PP film (thermoplastic Resin layer)

Claims (4)

[Claims] 1. A coating film layer is formed on both sides,
A metal can lid having a preformed opening, and an easy-peeling adhesive which is attached to the outer surface of the can lid so as to cover the opening from above the coating layer and adhere closely to the periphery of the opening. An easy-open can lid comprising an opening piece, wherein the opening piece has at least a side facing the outer surface of the can lid formed of a thermoplastic resin layer having a thermo-adhesive property, and the thermoplastic resin layer has Covering the cut end surface of the can lid, and also covering the coating film layer on the inner surface side of the can lid around the opening,
An easy-open can lid, which is adhered to the coating layer on the inner surface side of the can lid. 2. The thermoplastic resin layer portion covering the paint film layer on the inner surface side of the can lid is thinner at least at the peripheral portion as the distance from the opening increases. Item 4. An easy-open can lid according to Item 1. 3. The coating film layer formed on both surfaces of a metal plate is formed by painting and baking a paint in which a modified polyolefin resin powder is dispersed in a thermosetting resin solution, and 3. The easy-open can lid according to claim 1, wherein the heat-adhesive thermoplastic resin layer on the side of the piece facing the outer surface of the can lid is made of a polyolefin resin. 4. A can lid having an opening formed by punching an opening of a predetermined shape from a metal plate coated on both sides, and the can lid is provided with a number of openings provided in the can lid. The number of the protrusions is the same as the number of the protrusions, the protrusions have a diameter slightly smaller than the size of each opening, and an annular recess is formed around the protrusions, and the mold is heated in advance. The thermoplastic resin layer side of the opening piece, in which at least one side is formed of a thermo-adhesive thermoplastic resin layer, is placed around the opening on the outer surface side of the can lid. Then, the thermoplastic resin layer of the opened piece is placed on the outer surface of the can lid by pressing the opened piece on the side opposite to the thermoplastic resin layer with a heated pressing plate. And heat-bonded to the periphery of the opening, and the resin of the thermoplastic resin layer corresponding to the opening is A method for manufacturing an easily-openable can lid, wherein the can end is softened to cover the cut end surface of the opening and the periphery of the opening on the inner surface side of the can lid.