JPS62208347A - Molding cover for sealed vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a lid for a sealed container, particularly to a lid formed by drawing a laminate sheet.

Conventional technology Conventionally, sealed containers for non-carbonated beverages have been made by rolling a laminate sheet made by laminating metal foil and heat-sealing resin N/I on a paper base, and using synthetic resin on an aluminum foil base. Paper-based containers have been proposed in which a molded lid is heat-sealed by laminating a coated and peat-sealing resin and then drawing a laminated sheet.

Furthermore, in detail, as for the above-mentioned sub-drawing molded lid material, the inner layer is usually low-density polyethylene with a thickness of 30 to 100 μm, the middle layer is soft aluminum foil with a thickness of 80 to 130 μm, and the outer layer is 5 μm thick.
The laminate sheet is mainly made of aluminum foil coated with an epoxyphenol-based coating.

The reason why aluminum foil-based laminate sheets are conveniently used as the draw-formed lid material is that aluminum foil has excellent draw-formability and has excellent barrier properties that block contents such as juice from the outside air. It is from.

DISCLOSURE OF THE INVENTION The container is intended to replace metal cans. However, since aluminum foil-based molded M tends to be permanently deformed by weak force, it must be handled in the same way as metal cans. If the containers are transported at high speeds, the following problems will occur and the molded lids will be crushed as soon as they come into contact with guides, etc. during transportation on the filling line. It's difficult. On the other hand, during the distribution stage of containers, there is a problem in that the lids can be easily deformed due to containers colliding with each other during transportation, falling over or falling on display shelves, etc. Furthermore, when the container is applied to a vending machine, there is a drawback that the lid is deformed due to the impact of dropping when the vending machine is put in or taken out.

If the lid is deformed to a large extent, the sealing portion will be partially stretched and the sealing interface will peel off, causing aluminum corrosion and leakage.

The present inventor conducted a drop test on the conventional can, and found that when the can was dropped in a water drop state, the lid panel bent and deformed at a height of 15 cm, exceeding the product limit. When dropped vertically, many creases appeared around the periphery of the can lid at a height of only 50 m, exceeding the product limit.In this way, the conventional hermetically sealed container can be closed with a weak force. Since it causes permanent deformation, it is weak against impact force and loses its marketability.

As a countermeasure against the deformation of the conventional aluminum molded lid, it may be possible to make the aluminum foil even thicker, but this has the drawback of increasing costs due to the high cost of raw materials.

It is also conceivable to make the plastic layer of the molded lid thicker, but this poses a problem in that plastic has a large amount of spring back and poor drawability.

The present invention has been devised in view of the above-mentioned circumstances, and its purpose is to overcome the drawbacks of the conventional draw-formed lid mainly made of aluminum foil, and to have high strength, excellent formability, and low cost. We also offer cheap plastic-based molded lids.

Means for Solving the Problems In order to overcome the strength disadvantages of the conventional draw-formed lids mainly made of aluminum foil, the present inventors focused on a lid material mainly made of synthetic 1-liquor fat, and developed various 1-configuration lids. As a result of prototyping a laminate sheet and conducting intensive research, we determined the thickness of each layer, the thickness ratio of the metal foil layer to the reinforcing layer, and its bending stiffness in a laminate sheet consisting of a reinforcing material layer, a metal foil layer, and a thermal adhesive layer. The inventors have discovered that, by doing so, a draw-formed lid that is unprecedentedly superior in terms of strength, formability, and cost can be obtained, and the present invention has been achieved.

That is, the present invention provides a lid for a sealed container formed by drawing a laminate sheet containing at least (5) a reinforcing layer, (1) a metal foil layer, and (C) a thermal adhesive layer, in which (A) is a thermal adhesive layer with a relatively high modulus of elasticity. It is made of plastic resin and its thickness is in the range of 15 to 50 μm. It is in the range of 20 to 100μ. And a molded lid for a sealed container, characterized in that the thickness ratio of () and (4) is 0.06 or more, and the taper bending stiffness of the lid material is within the range of 20 to 300 gf@c@. .

The reinforcing layer A of the present invention occupies most of the lid material layer, and is made of a material with a relatively high elastic modulus among plastic resins in order to promote shape retention and high strength during drawing. Moreover, it is necessary to use relatively inexpensive materials.

Hard vinyl chloride, polyester, polystyrene, polypropylene, etc. are suitable as materials that meet these conditions. The optimum layer thickness is in the range of 100 to 400μ, preferably in the range of Fi150 to 350μ.

Metal foil layer B1-1, in order to suppress the springback of the reinforcing layer during drawing and improve drawing formability, and gas
Necessary for maintaining light barrier properties. In the present invention, in order to reduce costs, 15 to 50μ, preferably 4
Aluminum foil, electrolytic iron foil, and steel foil with a thickness of around 0μ are used.

Heat @ adhesion layer C, heat-sealing resin medium-density modified polyethylene, ethylene vinyl acetate, polypropylene,
Hot melt is used, and its layer thickness is suitably in the range of 20 to 100 microns.

The thickness ratio of the metal foil B and the reinforcing layer A is set to 005 or more in order to eliminate shape instability due to springback during molding.

In addition, if the taper bending stiffness of the laminate sheet lid material is less than 20 gf"0m, the strength will be weakened, and the strength will be lower than 300 gf".
If the gf11CWI or more is used, the cost will be high, and it will not be easy to crush, making it difficult to dispose of. Therefore, the range of taper bending stiffness from 20 to 300 gf*cg is i
ll 1. ing.

The order in which the reinforcing layer A and the metal foil layer B are laminated in the laminate sheet having the above layer structure does not matter, except that the thermal adhesive layer C is the inner layer. That is, the laminate sheet of the present invention is
The 111 layer structure is as follows from the outside: (a) Reinforcement layer, metal foil layer, thermal adhesive layer Iff) Metal foil layer, reinforcement layer, thermal adhesive layer (c) Metal foil layer, reinforcing layer, metal foil layer, thermal adhesive layer This includes each laminate sheet that is a layer. Said,
In the case of the NI layer structure (middle) and (c), since the extra foil layer is the outer layer, it is necessary to provide a coating film or a thin film of biaxially oriented polyester, nylon, etc. on the metal foil layer. Lamination of each of the above layers is performed by conventional dry lamination or extrusion lamination.

The laminate sheet having the above-mentioned structure is subjected to press molding and drawing processing to obtain a molded lid 1 as shown in FIG. 1.

The molded lid IVi obtained as described above had a small amount of return due to springback during the drawing process, and the desired molding depth could be obtained.

The draw-formed lid of the present invention can be applied to aseptic packaging containers, hot pack containers, and retort containers.

When applied to cylindrical, cup-shaped, or tray-shaped paper or plastic-based aseptic packaging containers, the rigidity of the containers was increased and strength was improved. When applied to a hot-pack container similar to the above-mentioned sterile packaging container, in addition to the above-mentioned effects, the volumetric contraction after hot-packing can be absorbed by pressing the outwardly bulging lid inward with a push tool. Kadesa was able to restore the deformation of the container. Furthermore, when applied to a cylindrical, cup, or tray-shaped plastic retort container, the diaphragm effect of the lid prevents the container from deforming due to internal pressure changes during the retort. The molded lid can be easily heat-sealed to each container by high-frequency induction heating or ultrasonic heating. 52 Clarification: A laminate sheet was prepared by laminating the examples of * configurations shown in Table 1 using a dry lamination method using urethane adhesive. The laminate sheet was drawn by press molding to form a molded product with a depth h of 8fl and a lid diameter d5.
With three dragons in mind, a molded lid l as shown in Figure 1 was created.The resulting molded lid is as shown in Figure 2. A can body 2 (B = 132-250 g) consisting of a layer, a low-density polyethylene layer, an aluminum foil layer, and a medium-density modified polyethylene layer was hot-packed, and a molded lid 1 was similarly heat-sealed to the top of the can body. The heat sealing method was a conventional method as described in, for example, Japanese Unexamined Patent Publication No. 13637/1983.

The limit height at which the container filled with the contents 3 above will be dropped vertically and lose its marketability due to deformation is 5j for each! Measurements were made on the lid material of the example.

Similarly, the lid materials of each comparative example were drawn under the same conditions as described above, and the same drop test was conducted using the same can body KiM.

The above results are shown in the table below.

Note) 1) Numbers are thickness μ, PVC: Hard PVC, PET
: Unstretched polyester, PC=polycarbonate, O
PS: Biaxially oriented polystyrene (magnification 9), CPP: Unoriented polypropylene LDPE: 4-density polyethylene A
t: Soft aluminum foil, PE: Medium density polyethylene 2) According to JISP-8125 method, 38.1 width x 7
The 15 bending moment of 0 length is determined, and the average value of MD, TD, front bending, and back bending is shown. Room temperature measurement 3) 7 Lunge refers to the state shown in Figure 3, and distortion refers to the state of being bent in one direction as shown in Figure 4. These have a large springback property and are likely to occur if there is no shape retention property.

4) Judgment by manually applying force to the joint between the body and the lid in the radial direction As is clear from Table 1, the conventional molded lid mainly made of aluminum foil has good formability and crushability. , the critical height due to falling is low considering the bending stiffness (see Comparative Examples 11-14). In addition, the moldability differs depending on the reinforcing layer that does not contain aluminum foil, the lid material of the thermal adhesive layer, and the Netsucho plastic resin, but LDPJ
Materials that can hardly be formed into CPP shapes and biaxially stretched PS
(ops) stretched to crazing (ops)
Although it can be molded to some extent like #), PVClPET, and PC, which have cracks), the molded lid is unstable and undesirable, such as flange standing and distortion.

Compared to these comparative examples, the moldability of the present invention is good by setting the thickness ratio of the metal foil to the reinforcing layer to 006 or more.

Moreover, when the taper bending stiffness exceeds 300gf11cm, the crushability is poor (see Comparative Example 4). It is thought that there is a correlation between taper bending stiffness and container drop strength.
From the point of view of the practical drop strength of the container, the taper bending stiffness is 2.
0gf11C1n or more is inevitable.

FIG. 5 is a graph showing the results of measuring the relationship between the bending stiffness of the lid material and the limit height of the container by the taper method for the example of the present invention and the conventional aluminum-based container. As is clear from the figure, the bending stiffness of the lid of the present invention is several times higher than that of the conventional lid for both water drop and vertical drop, and it is clear that the lid has particularly excellent drop resistance. .

As described above, the draw-molded lid of the present invention has excellent moldability even though the lid material is mainly made of plastic, so it is possible to obtain the desired molding depth and prevent flange distortion. A molded lid is obtained. Furthermore, by applying it to a sealed container, the container's resistance to drop impact can be greatly improved, and the deformation caused by impact, which has traditionally been the biggest problem with this type of container, can be eliminated. Furthermore, since it has excellent crushability, used containers can be easily crushed and are easy to dispose of. Furthermore, since a low-cost general-purpose thermoplastic resin having a relatively high elastic modulus can be used, an inexpensive lid can be provided. The lid of the present invention has appropriate elasticity and light resistance.
Since it has gas barrier properties, it can be applied to all types of containers such as sterile packaging, hot packs, retort containers, etc.

As described above in detail, according to the present invention, it is possible to provide a molded lid with high marketability that is superior to conventional ones in all aspects including moldability, impact resistance, and cost.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of an embodiment of the draw-formed lid of the present invention, and FIG.
The figure is a side sectional view of a container to which a molded lid has been applied, Figure 3 is a side view of a molded lid with 7 lunges formed during molding, Figure 4 is a side view of an unshaped lid with distortion during molding, and Figure 5 The figure is a graph showing the relationship between the bending stiffness of the lid material and the critical fall height. 1: Molded lid 2: Can body 3: Liquid content Patent applicant Toyo Seikan Co., Ltd. Patent attorney Patent attorney Yoshifumi Sa (and 2 others)
Figure 1 Figure 2 Figure 3 Figure 5

Claims (1)

[Claims] A lid for a sealed container formed by drawing a laminate sheet lid material comprising at least a reinforcing layer, a metal foil layer, and a thermal adhesive layer,
The reinforcing layer is made of a thermoplastic resin having a relatively high modulus of elasticity and has a thickness of 100 to 400μ, the gold foil layer has a thickness of 15 to 50μ, and the thermal adhesive layer is arranged as the innermost layer. Composed of heat-sealable resin with a layer thickness of 20~
100μ, a layer thickness ratio of the total metal foil layer to the reinforcing layer is 006 or more, and a tapered bending stiffness of the lid material is 20 to 300 gf·cm.