JPH0585424B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to various cans such as beverage coffee cans, soup cans, motor oil cans, edible oil/seasoning cans, and similar containers, that is, can-like containers. The present invention relates to a lid constituting a can-like container lid made mainly of synthetic resin, and relates to a technology that can improve the opening (opening) characteristics particularly at high temperatures and the strength to break the can when the can is dropped.

[Conventional technology]

The present inventors previously proposed the following can-like container lids mainly made of synthetic resin as described above.

For example, an Al foil having an unstretched, easily heat-sealable synthetic resin layer on both sides can be reformed into a desired lid shape in a flat state or without substantially stretching the Al foil. and set it in the injection molding machine mold in advance.
A can-like container lid is constructed by injecting resin into this and simultaneously (integrating) injection molding.

According to this, since the molten resin produced by injection is laminated on the easily heat-sealable resin layer on the Al foil, the adhesion strength is high, and even if subjected to heat history such as retort treatment, the above-mentioned injection resin layer part of the molded product will peel off. It has the advantage that it does not cause any damage, and the final molded product has high drop strength.It also has the advantage that the number of steps can be reduced and the cost can be reduced by simultaneous integral molding. .

In the above-mentioned injection-molded upper lid, the surrounding flap portion is attached to the can-like container body having a surface of a similar non-stretched, easily heat-sealable synthetic resin layer.
The unstretched, easily heat-sealable synthetic resin layer on the side opposite to the side on which the injection resin layer is laminated on the surface of the Al foil allows it to be attached by heat sealing, and also on the inner side of the flap around the lid. In the lid panel part of , no injection resin layer is laminated, that is, Al foil (multilayer base material) having non-stretched, easily heat-sealable synthetic resin layers on both sides is exposed.
A score part (cutout part) is formed in a band shape and, for example, an elliptical shape, and one end of the handle part is fixed to a pedestal part made of an injection resin layer on the inside of this score part. By lifting the other end of the handle upward, the multilayer base material of the score part is torn apart, and by pulling the handle, the score part is cut, thereby opening the can with the injection-molded lid. (opening).

However, in such a can-like container in which a lid is attached to the body by simultaneous injection molding, the multilayer base material in the score part contains an unstretched film of an unstretched easily heat-sealable synthetic resin, such as an olefin resin. Because of this, when trying to open a hot can of coffee or soup, for example, the resin layer of the score part may cause the elongation of the cut part, which is characteristic of cutting and tearing metal foil. As a result, it tends to stretch easily, and hairs tend to form on the cut ends, making it impossible to produce clean cut ends, giving an unhygienic feel. Furthermore, since metal foil is used as the barrier material, its elasticity against bending is low, so there is a drawback that it is easily damaged by attacks.

[Problem to be solved by the invention]

The present invention aims to solve such problems and provide a lid for a can-like container with improved opening characteristics, and also to provide a lid for a can-like container made of synthetic resin such as the one covered by the present invention. It is also an object of the present invention to improve the can drop strength of the score section, which is required to be provided.

[Means to solve the problem]

The present invention is a lid made by laminating synthetic resin layers by injection molding on a multilayer base material comprising a barrier base material made of metal foil and an easily heat-sealable non-stretchable layer made of synthetic resin on both sides, and a can-like container lid comprising a score portion in which the multilayer base material is exposed on the panel portion of the lid, at least one of the easily heat-sealable unstretched layer of the multilayer base material and the barrier base material. The present invention relates to a can-like container lid characterized in that a layer made of a stretched synthetic resin film is interposed between the layers.

[Effect]

Describing the effects of the present invention with examples,
When a layer made of a stretched film is interposed, the stretched film inherently has high tensile strength and edge tearing strength, so when the can is opened at high temperatures and when the can is dropped, the edges or center of the stretched film are If there is no tear, tear propagation will hardly occur, but once
When a tear occurs, the tear propagates easily, and there is no elongation at the cut end unlike in the case of metal foil, so the unstretched easily heat-sealable layer in the multilayer base material can be used at the same time as the stretched film. The lid can be torn and cut without stretching or creating whiskers, making it easier to open the lid. In addition, by interposing a layer made of such a stretched film, damage to the metal can be reduced.
That is, the can-drop strength when the product is dropped is also improved, and in particular, can-opening characteristics at high temperatures are improved.

〔Example〕

Next, embodiments of the present invention will be described based on the drawings.

FIG. 3 shows a plan view of an example of the upper lid main body before attachment of the handle, which was previously proposed by the present inventors, and FIG. 4 shows a sectional view taken along the line of FIG. 3.

The upper lid body 1 has a flap portion 2 at its peripheral end.
and a panel part 3 inside thereof.

The upper lid main body 1 includes an injection resin layer 5 on a multilayer base material 4.
It is made up of layers.

The panel part 3 is provided with a score part (cutout part) 6 in which the injection resin layer 5 is not laminated and the multilayer base material 4 is exposed, as shown in FIG. Preferably, the entirety is formed into a curved shape. FIG. 3 shows an example of an elliptical shape.

As will be described later, the lid is opened along the outer peripheral edge 7 of the band-shaped score portion 6.

A semicircular pedestal part 8 for attaching a handle part is provided on the inner side of this score part 6 and on the left side in FIG. An existing part 9 is provided.

The square-shaped interior surrounded by the extension part 9 and the pedestal part 8 is an exposed part 10 of the multilayer base material 4, similar to the score part 6.

Although this rounded portion 10 is an exposed portion of the multilayer base material 4 in the above embodiment, the injection resin layer 5 may be laminated thereon.

A boss 11 is erected on the base portion 8.

FIG. 5 shows a handle part 12 attached to the upper lid main body 1 shown in FIG. 3.
An example plan view of the upper lid 13 with the upper lid 13 attached is shown. Also,
FIG. 6 shows a sectional view taken along the line of FIG.

The attachment of the handle portion 12 to the boss 11 is performed, for example, by
A number of circular holes, for example, corresponding to the number of bosses 11 are made in the tip of the handle part 12, the head part of the boss 11 is made to protrude from the hole, and the protruding head part is melted by ultrasonic welding to close the hole. This can be done by filling the

The handle portion 12 is made of resin, and is attached to the lid body 1 by post-fitting as described above.

FIG. 7 shows a plan view of a lid formed by attaching a handle 14 different from that shown in FIG. 5 to the upper lid main body 1 similar to that shown in FIG. A drinking straw can be inserted into the multilayer substrate 4 through this hole 140. FIG. 8 shows a sectional view taken along the line shown in FIG. 7, and FIG. 9 shows the lid 1 shown in FIG.
5 is attached to a body 16 constituting a can-like container through its flap portion 2, and a bottom lid 17 is further attached to the lower part of the body 16 to constitute a can-like container.

In addition, Fig. 10 is a plan view of the upper cover after opening, and the first
FIG. 1 shows a sectional view taken along the - line in FIG. 10.

That is, to explain an example of the opening of the upper lid with reference to FIG. 6, as shown by the arrow in FIG.
When the other end of the handle 12 is lifted, the tip of the handle 12 sinks into the multilayer base material 4 and breaks through, and when the handle 12 is continuously pulled, the lid breaks along the outer peripheral edge 7 of the score part 6. The opening is now done by cutting.

In the case of the can-like container lid of the present invention, the score portion 6
Therefore, the lid panel portion 3 may be separated into an open portion and other portions, the score portion 6 may be formed into a curved shape such as an ellipse with an appropriate width, or the score portion 6 may be formed as close to the upper lid flap as possible. Since the handle parts 9 and 14 are firmly attached to the boss 11 by ultrasonic welding, it is possible to provide a can-like container lid with excellent opening property. The multilayer base material 4 is made of I did it like that.

This will be explained with reference to FIGS. 1 and 2. These figures show an example of the multilayer base material 4 used in the present invention, and FIG. 1 shows the non-stretchable heat-sealable layer of the multilayer base material. FIG. 2 shows a cross-sectional example of a structure in which a layer of stretched film is interposed between the barrier layer and the barrier layer, and FIG. 2 similarly shows a cross-sectional example of a structure in which only one layer of the stretched film is interposed. .

In these figures, 18 is a layer made of a stretched film, 19 is a barrier base material, and 20 and 21 are unstretched heat-sealable synthetic resin layers.

Examples of the stretched film constituting the layer 18 made of the stretched film include a stretched polypropylene film, a stretched polyester film, and a stretched polyamide film.

The barrier base material 19 needs to have so-called gas and liquid barrier properties that prevent the permeation of oxygen, moisture, and the like.

Examples of the barrier base material 19 include metal foil, sheet, film, etc., but the present invention
In particular, it relates to a can-like container lid made of this aluminum foil as the barrier base material 19. Examples of other barrier substrates 19 include sheets and films of saponified ethylene-vinyl acetate copolymers, polyvinylidene chloride, polyamides, polyacrylonitrile, and the like.

As mentioned above, the can-like container lid according to the present invention is designed to be opened by cutting the multilayer base material 4 having the barrier base material 19, and is easy to open.
In view of the relationship with the drop strength, can breaking strength, and breaking strength during molding when used as a product, it is desirable that the thickness of the barrier substrate 19 such as aluminum foil is 50 μm or less, preferably 9 to 30 μm.

In addition, by having such a thickness, complete incineration is possible, and the incineration calories are 5000 ~
It can be reduced to 6000kcal/Kg and solve the problem of empty can disposal.

The multilayer base material 4 has non-stretched easily heat-sealable synthetic resin layers 20 and 21 on each of the front and back surface layers.

The can-like container lid according to the present invention is attached to the body 16 of the can-like container, as described above. This torso 16
By using a material having a similar resin layer surface, heat sealing between the lid and the body can be easily performed.

The inner layer 20 is an easily heat-sealable layer on the side that is attached to the body of the lid, and the easily heat-sealable layer is on the side that is heat-sealed to the injection resin layer 5 that is laminated on the multilayer base material 5 by injection molding or the like. Assuming that the layer is the outer layer 21, it is preferable that the multilayer base material 4 according to the present invention has inner and outer layers 20 and 21 formed as shown in the above embodiment. Due to the presence of this outer layer 21, a lid with high adhesion can be formed by thermal fusion with the injection resin layer 5, and as mentioned above, the heat seal between the container body and the lid can be This can be achieved very easily by making the resin layer non-stretched.

As the resin constituting the easily heat-sealable layers 20 and 21, a polyolefin resin that can be melted and bonded by heat is typically used.

Both the inner and outer layers 20 and 21 may be made of the same resin, or may be made of different resins.

When forming the easily heat-sealable layers 20 and 21 on the gas barrier substrate 19, it is recommended that they be formed by extrusion lamination with or without an adhesive resin layer such as an adhesive or a film-like hot melt adhesive. can.

The thickness of the easily heat-sealable layers 20 and 21 is set to one side for the same reason as the barrier base material 19 described above.
It is preferably 100μ or less.

In this case, the inventors have found that if the inner layer 20 is made thinner than the outer layer 21, the can opening performance is further improved.

The can-like container lid according to the present invention can be obtained, for example, as follows.

This will be explained with reference to FIGS. 12 to 14. As shown in FIG. 12, the multilayer base material 4 is inserted into the guide member (stripper plate) 22. This may be done while adsorbing the multilayer base material 4 to the moving cylinder 23 of the robot.

As shown in Figure 13, the stripper plate 2
While fixing the multilayer base material 4 inside the mold 2 to prevent displacement, the mold is clamped as shown in FIG. By this mold clamping, the end of the flat (two-dimensional) multilayer base material 4 is bent in the mold (core mold, receiving mold) 24 as shown in FIG.
and a mold having a gate 26 (cavity mold,
The molten resin is injected from the gate 26 of the injection mold 27 into the cavity (mold space) 28 formed between the core mold 24 and the cavity mold 27, and a second layer of the molten resin is deposited on the surface of the multilayer base material 4. Resin layer 5
are laminated, and furthermore, a boss 11 is erected on the pedestal part 8 made of this resin layer 5, and an extension part 9 is further provided.
A lid main body 1 having the following is obtained.

In this way, by injecting the resin 5 onto the multilayer base material 4, the flap part 2 and the panel part 3 are formed.
It is made of the injection resin layer 5 and has an integrally molded pedestal part 8, a boss 11 erected on the pedestal part 8, and an extension part 9 extending from the pedestal part 8. It is possible to obtain a lid body 1 having a notch 6 which can be formed at the same time.

The handle portion 12 is preferably manufactured from the same resin in a separate process from the injection molding described above, and attached to the boss 11 by ultrasonic welding.

The lid main body 1 of the can-like container lid of the present invention can be obtained as described above, but when the lid is deep, the present invention has found that it is even better to do as follows through subsequent research on such injection molded lids. . This will be explained with reference to FIGS. 15 and 16.

A disc-shaped multilayer base material 4 as shown in FIG.
The female mold 3 is set between a male mold 31 having vertical grooves 29 and 30, respectively, and a female mold 32, which has a brim-like flat plate surface on the upper surface but is not shown.
The male mold 31 is inserted into the hollow part of 2, and the excess portion of the multilayer base material is absorbed in the longitudinal direction as wrinkles 33, thereby forming the flange part 34 and the body wall part 35 without substantially stretching the multilayer base material 4. a container-like preformed multilayer substrate 3 having a bottom portion 36 and a bottom portion 36;
Set it to 7.

The flange portion 34 is formed by a brim-shaped flat plate surface on the upper surface of the male mold 31.

This preformed multilayer base material 37 is set in an injection mold 38, and the injection resin 5 is injected.

During injection, the multilayer base material 37 is pressed against the mold 38 by the resin pressure of injection molding, and the wrinkles 33 are smoothed.

This prevents irregular large wrinkles that occur in the multilayer base material 4 that occurs in the flat insert molding method shown in FIGS. 12 to 14, and as shown in FIG. To prevent seaming defects from occurring when welding a flange part 2 made of a second resin layer to a body part 16 of a can-like container by high-frequency induction heating (high-frequency induction heating is possible due to the presence of an Al layer). The barrier base material 19 of the multilayer base material 4 can be formed by local heating.
Furthermore, since it is preformed without substantially stretching, thin Al foil can be used, and the resulting molded product has the advantage that the Al layer becomes a uniform thin layer. can. Various types of resins can be used for the injection resin 5 used in the present invention, including synthetic resins such as polyolefins such as polypropylene and ethylene polypropylene copolymer, which have excellent heat resistance against high temperatures during retort sterilization. Synthetic resins are exemplified.

An inorganic filler may be mixed with the injection resin. Mixing an inorganic filler has the following advantages.

The dimensional stability of the can-like container is improved and the shrinkage rate is reduced, which is advantageous.

The heat resistance is improved and the heat distortion temperature is increased, which is advantageous for retorting.

Burned calories are reduced and combustion furnaces are not damaged, which is advantageous for empty can disposal.

It can provide rigidity, which is advantageous in terms of product distribution.

Heat conduction becomes good, which is advantageous for retorting.

Cost can be reduced.

As the inorganic filler, any filler that is widely used in the fields of synthetic resins and rubbers may be used. These inorganic fillers are preferably inorganic compounds that have good food hygiene properties, do not react with oxygen and water, and do not decompose during kneading and molding. Examples of the inorganic filler include compounds such as metal oxides, hydrates (hydroxides), sulfates, carbonates, and silicates;
It is broadly classified into these double salts and mixtures thereof. Typical examples of such inorganic fillers include aluminum oxide (alumina), its hydrates, magnesium oxide (magnesia), zinc oxide (zinc oxide), lead oxides such as red lead and lead white, magnesium carbonate, and carbonate. Calcium, basic magnesium carbonate,
White carbon, asbestos, mica, talc, glass fiber, glass powder, glass beads, clay, diatomaceous earth, silica, wollastonite, iron oxide, antimony dioxide, titanium oxide (titania), lithopone, pumice powder, aluminum sulfate (gypsum) ), silica zirconium, zirconium oxide, barium carbonate, dolomite, molybdenum sulfide, and iron sand. Among these inorganic fillers, those in powder form preferably have a diameter of 20 microns or less (preferably 10 microns or less).
In addition, fibrous materials have a diameter of 1 to 500 microns (preferably 1 to 300 microns) and a length of 0.1 microns.
-6 mm (preferably 0.1-5 mm) is desirable.
Furthermore, it is preferable that the diameter of the flat plate is 30 microns or less (preferably 10 microns or less). Among these inorganic fillers, those in the form of flat plates (flake) and those in the form of powder are particularly suitable.

In addition, various additives such as pigments may be added to the injection resin.

〔Effect of the invention〕

According to the present invention, by interposing a layer made of a stretched film (stretched layer) between at least one layer of the non-stretchable heat-sealable layer and the barrier material of the multilayer base material, the tear propagation characteristics of the stretched layer can be improved. At the same time as the stretched layer is cut, the entire multilayer base material is cut while forming a clean cut portion, and the lid can be opened even more easily. In addition, by making the layer non-stretched, it is separated from the characteristics of the stretched layer, eliminating the difficulty of heat sealing unlike the stretched layer.

Furthermore, the presence of the stretched layer made it possible to supplement and improve the drop strength of the metal foil.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a multilayer base material for a can-like container lid showing an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a multilayer base material for a can-like container lid showing another embodiment of the present invention. FIG. 3 is a plan view of the upper lid body showing an embodiment of the present invention;
FIG. 4 is a sectional view taken along the line - - in FIG. 3, FIG. 5 is a plan view of the top cover showing an embodiment of the present invention, FIG. 6 is a sectional view taken along the line - FIG. 8 is a cross-sectional view taken along the line -- in FIG. 7, FIG. 9 is a perspective view of a can-like container showing an embodiment of the present invention, and FIG. 10 is an embodiment of the present invention. FIG. 11 is a sectional view taken along the - line in FIG. 10, FIGS. 12 to 14 are explanatory diagrams of the lid forming process, and FIG. FIG. 16 is an explanatory cross-sectional view of the lid forming process. 1... Lid main body, 2... Panel part, 4... Multilayer base material, 5
...Injection resin layer, 6...Score part, 13...Top lid, 1
5... Upper lid, 16... Body part, 17... Lower lid, 18... Stretched film, 19... Barrier base material, 20, 21...
Easy heat sealing layer.

Claims (1)

[Claims] 1 A lid made by laminating synthetic resin layers by injection molding on a multilayer base material comprising a barrier base material made of metal foil and an easily heat-sealable non-stretchable layer made of synthetic resin on both sides, and In a can-like container lid having a score part in which the multilayer base material is exposed in the panel part of the lid, a composite material is formed between at least one of the easily heat-sealable non-stretchable layer of the multilayer base material and the barrier base material. A can-like container lid characterized by having a layer of stretched resin film interposed therebetween.