JPH0659907B2 - Easy-open container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an easily openable container. More specifically, the present invention is capable of firmly heat-sealing a lid material that is preferably used for packaging foods, particularly for heat sterilization packaging, has excellent sealing properties, and is easy to open even when the position of the heat seal is displaced. The present invention relates to an easy-open container that does not impair the property.

[Conventional technology]

2. Description of the Related Art Conventionally, a flanged container has been widely used for packaging foods and the like, and the container is filled with contents and then sealed by heat-sealing a lid member. However, in the heat-sealed container formed in this way, if the heat-sealing strength is increased and the sealing property is improved, the unsealing property when using the contents is poor, and it is necessary to open it with a knife or the like. If a material with an appropriate sealing strength is selected to improve the sealing performance, the sealing performance will change significantly due to heat sealing conditions such as temperature, pressure, time, etc. Since the property is deteriorated, there is a drawback that it cannot be used for packaging having a high internal pressure such as heat sterilization such as retort.

[Problems to be solved by the invention]

In order to solve this problem, the present applicant uses a multilayer container body as the container body, and does not perform the opening at the time of use between the commonly used seal layers, but uses the interlayer of the multilayer container as an opening and peeling surface, and heat. By making a cut in the innermost layer inside the seal portion, we proposed an easily openable container in which the lid material is peeled off together with the innermost layer while leaving the innermost layer in the multilayer container body inside the cut without being peeled off. However, although this container is excellent in easy-opening property, it is difficult to heat-seal correctly to the outside of the annular cutting line (cut) for opening and peeling, and it is heat-sealed to the inside of the cutting line due to the seal shift. Inconvenience such as was easy to occur. In addition, the sealing method of this method requires difficult peeling from the inside of the container when receiving internal pressure during retort treatment, etc. It is necessary to provide a gap of about 0.5 to 10 mm, but it was difficult to accurately control the heat seal position in the flat flange portion.

The present invention has improved these, and can perform heat sealing without causing a positional deviation of the sealing position, facilitates the sealing work, and is a strong seal capable of accurately controlling the gap between the cutting line and the inner end of the heat sealing portion. The present invention aims to provide an easy-open container having openness and easy-open property.

[Means for solving problems]

That is, the present invention is a container comprising a multi-layer container body and a lid material that is heat-sealed with a flange portion of the multi-layer container body, and the interlayer adhesive force of the multi-layer container body is calculated from the adhesive force between the flange portion and the lid member. The heat non-fusing layer is formed on at least one of the flange portion and the lid member inside the heat seal portion, and the annular cutting line is provided inside the heat seal portion of the flange portion. An easily openable container characterized by the above.

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 4 is a partial cross-sectional view of the easy-open container proposed by the present applicant. 1 is the innermost layer of the multilayer container body, and 2 is the layer in contact with it. After filling the contents of the flange portion 3 with a lid member (4, 5), the lid member 3 is tightly heat-sealed with the innermost layer 1 of the multilayer container body and the flange portion 3. Reference numeral 6 denotes a heat-sealing portion, and the multilayer container and the lid member are heat-seal-resistant with an opening flange portion of the multilayer container. 7 is a cutting line. A gap t of 0.5 to 10 mm is provided between the inner end of the heat seal portion and the cutting line.
The stress concentrates on the points, and the peel strength from the inside becomes larger than the peel strength from the outside. However, if the flange portion is flat, it is difficult to control the size of t by heat sealing.

FIG. 1 (a) is a partial sectional view of an embodiment of the easy-open container of the present invention. In this case, the flange portion 3 of the multi-layer container body
The heat non-fusion layer 8 is formed inside the heat seal portion 6, and even when the flange portion and the lid member are heat sealed by the heat seal ring, this portion is not sealed.
Therefore, a constant space can be provided between the inner end of the heat seal portion and the cutting line. In FIG. 1 (a), the thermal non-fusion layer is provided on the flange portion, but the thermal non-fusion layer may be provided on the lid member. The heat non-fusion layer is not limited in material as long as it prevents heat fusion between the flange portion and the lid material when heat sealing the flange portion and the lid material. A cutting line 7 is provided in advance on the heat-non-fusing portion of the innermost layer 1 of the flange portion. When heat sealing is performed using such a container, the length of t can be controlled to be constant even if the heat sealing is deviated, and sufficient sealing property and easy opening property can be exhibited. Reference numeral 9 is a knob for facilitating opening.

FIG. 1 (b) is a partial cross-sectional view showing the peeling of the heat-sealed cover material of FIG. 1 (a). After delamination of the multilayer container body occurs, the innermost layer is cut along the cutting line and the lid material is peeled off.

FIG. 2 (a) and FIG. 2 (b) are cross-sectional explanatory views showing an example of simultaneously performing heat-sealing and forming a cutting line of the easy-open container of the present invention. The heat seal ring 10 is integrally provided with a seal portion 11 for performing heat seal and a ring body 12 for heat pressing at a distance t from the seal portion. When heat sealing and cutting line formation are performed simultaneously in this manner, t can be kept constant, work can be performed efficiently, and heat sealing and cutting line formation can be performed without impairing the shape of the container. Is possible. However,
In this example, when setting the pressure for pressing the heat seal ring, the length of the annular body 12, and the like, it is necessary to set the conditions such that the lid member is not damaged when the cutting line is formed. Further, it is preferable that the material of the layer 2 in contact with the innermost layer has a higher melting point and softening point than the material of the innermost layer 1 so as not to impair the shape of the multilayer container body.

FIG. 3 is a sectional view of an embodiment in which a reinforcing rib 13 is provided on the outer edge portion of the flange portion of the easy-open container of the present invention. In order to facilitate the peeling, the cutting line 14 is also provided on the innermost layer of the outer edge portion of the flange portion. Curls may be provided for reinforcement instead of the ribs.

In the present invention, the cutting line 7 provided on the flange portion is for cutting the inner layer at the inner peripheral portion of the flange portion when the lid material is peeled off, and this cutting line is usually provided as an annular notch. Any material may be used as long as it can easily cut the innermost layer when the material is peeled off, and may be cut up to the layer in contact with the innermost layer or only a part of the innermost layer. Also, this cutting line is a circle, a triangle,
It may be provided in an annular shape such as a quadrangle around the entire inner circumference of the flange, or a part thereof may be left. If the lid material is to be peeled off while it is still attached, do not insert cutting lines only in that portion.

The cutting line can be formed by pressing the heated annular body as described above, by pressing the annular blade, by cutting with a cutting blade, by ultrasonic processing, by laser processing, or by shearing force. Or a combination thereof.
The cutting line is formed at the step of heat-sealing the lid material to the multilayer container body described above, at the step of forming sheet, at the step of forming multilayer container body, and at the step after forming multilayer container body. (Normal container molding and sealing state) can be performed at a stage after heat sealing the lid member to the multilayer container body.

The length t from the inner edge of the heat seal to the cutting line is usually 1 mm
-10 mm, preferably 1.5 mm to 5 mm.

The shape of the container of the present invention is not particularly limited,
Usually, it is a circle, a square, or the like, and is heat-sealed annularly along the flange portion of this shape. Further, it may be cup-shaped or tray-shaped.

Although the lid members 4 and 5 are two-layer films in FIG. 1,
It may be either a single-layer film or a multi-layer film, and there is no particular limitation. Explaining the case of using a multi-layer film, a plastic single-layer film, a multi-layer film, a paper, an aluminum foil, or a base material composed of a composite material of these, polyethylene, polypropylene, ethylene-α-olefin copolymer, ethylene A sealant layer made of a resin having an easy heat sealability with the innermost layer of the multilayer container body made of a vinyl acetate copolymer or the like is preferably used.

Explaining the multilayer structure of the multilayer container body, the interlayer adhesive force of the multilayer container body is smaller than the heat seal strength between the lid material and the multilayer container body, and when peeling the lid material, peeling occurs between the layers of the multilayer container body, There is no particular limitation as long as the material can be easily opened, but the delamination strength is 200 to 15
00 g / 15 mm (pulling speed 300 mm / min, the same applies hereinafter), preferably about 300 to 1200 g / 15 mm, and may be appropriately determined depending on the field of use of the container. The thickness of the inner layer of the flange is usually 5 to 150 μm, preferably 10 to 100 μm.

The material of such a multi-layer container body is not particularly limited, polyolefin resin, polystyrene resin, polyamide resin, polyester resin, thermoplastic elastomer, etc., or a mixture thereof, and further various additive-containing resins, Resins in which an inorganic filler is mixed in an amount of 5 to 70% by weight are available. A resin suitable for the intended peel strength may be selected by combining the layers made of these resin mixtures.

Next, as the material of the main body of the multi-layer container for retort, preferably used is a combination of (a) a mixed resin layer of polypropylene resin and polyethylene resin and (b) a high-density polyethylene resin layer. The polypropylene-based resin used in this mixed resin layer includes, in addition to a highly crystalline propylene homopolymer, ethylene, butene-1,
Examples thereof include random copolymers with α-olefins such as pentene-1,3-methylbutene-1,4-methylpentene-1, and mixtures thereof. The random copolymer may be a mixture with homopolypropylene obtained by multistage polymerization. In the above copolymer, it is preferable that the proportion of the copolymerized monomer is 10 mol% or less. Further, these polypropylene-based resins preferably have a melt index (MI) in the range of 0.1 to 20.

On the other hand, as the polyethylene-based resin used in the mixed resin layer, low density (high pressure method low density polyethylene, linear low density polyethylene, etc.), medium density and high density polyethylene can be used. In addition to ethylene homopolymer, propylene, butene-1, pentene-1, 3-methylbutene-1, 4-methylpentene-
A crystalline or low crystalline or amorphous random or block copolymer with an α-olefin such as 1 or vinyl acetate, or a mixture thereof can also be used. In the above copolymer, the proportion of the copolymerized monomer is preferably 20 mol% or less. In addition, these polyethylene-based resins have a melt index of 0.02 to
It is preferably in the range of 50 and density of 0.850 to 0.980 g / cm ³ .

The ratio of the polypropylene resin to the polyethylene resin is preferably 50:50 to 97: by weight.
3, more preferably 60:40 to 95: 5.

Furthermore, if desired, a third resin component can be added to the resin mixture to improve its compatibility. Examples of such a third resin component include modified polyolefins modified with unsaturated carboxylic acids or their derivatives, ethylene-vinyl acetate copolymers, ethylene-
Acrylate copolymer, ethylene-propylene rubber, ethylene-propylene-diene rubber, polybutene, polyisobutylene, polybutadiene rubber, polyisoprene rubber, atactic poly-4-methylpentene-1,
Examples thereof include styrene-butadiene rubber, acrylonitrile-butadiene rubber, and ion-crosslinked olefin copolymer (ionomer). These may be used alone or in combination of two or more. These third components are 100 parts by weight of polypropylene resin,
It is preferably used in an amount of 30 parts by weight or less.

Examples of the high-density polyethylene resin used for the high-density polyethylene resin layer of the other layer of the multilayer container body of the present invention include ethylene homopolymer, propylene, butene-1, pentene-1,3-methylbutene- Examples thereof include copolymers with α-olefins such as 1,4-methylpentene-1. In this copolymer, the proportion of the copolymerization monomer is preferably 10 mol% or less. This high-density polyethylene resin has a density of 0.940 to 0.975 g / cm ³
Is preferable, and a mixture of those having different densities and molecular weight distributions may be used.

The multilayer container body of the present invention comprises the resin layer as described above.
Although it may be a layered container, a multilayered container having three or more layers in which layers of other materials are further laminated may be used for the purpose of improving gas barrier properties and reducing deformation of the container. Examples of other materials include those having excellent gas barrier properties such as ethylene-vinyl alcohol copolymer, polyvinylidene chloride, nylon, polyethylene terephthalate, and other resin layers, and alum vapor deposition layers. 2 layers of other materials
It may be a laminated body composed of layers, or may be a multilayer laminated body composed of three or more layers, and inorganic fillers 10 to 8
It may have a resin layer containing 0% by weight.

The layer structure of the multilayer container body is appropriately selected depending on the sealant layer resin of the lid material. For example, when the lid material is a polyethylene sealant layer, in the combination of the above resin layers, the high-density polyethylene layer is the innermost layer of the container. And When the cutting line is formed by heating means, it is preferable that the material of the layer in contact with the innermost layer has a higher melting point and softening point than the material of the innermost layer so as not to damage the shape of the multilayer container body. . For example, it is preferable that the material of the innermost layer is polyethylene resin and the material of the layer in contact with the innermost layer is a resin mixture of polyethylene resin and polypropylene resin.

In the multilayer container body of the present invention, as long as the multilayer container body has the feature of the present invention having a release layer, other layers such as a seal layer may be provided inside the innermost layer of the multilayer container body, if necessary. You may have.

Further, the material used for forming the heat-non-fusing layer is not particularly limited as described above and is a high melting point thermoplastic resin or thermosetting resin, for example, polyamide resin, polyester resin, polyamide -A nitrified cotton copolymer, a nitrified cotton-silicon resin copolymer, a silicone resin, a urethane resin, an aminoalkyd resin, a wax and the like can be used, and the thickness thereof is preferably about 1 to 5 μm. The thermal non-fusing layer is formed by coating, printing, especially gravure printing, sticking and the like.

This multilayer container body is obtained by molding a coextruded multilayer sheet or a laminated sheet by vacuum molding, pressure molding, etc. using the above-mentioned combination of resins, or by multilayer injection molding, multilayer injection blow molding, multilayer blow molding, etc. be able to. Further, it can be obtained by thermoforming the multilayer film inside a container such as paper.

As the laminating process, for example, a method such as extrusion laminating, hot melt laminating, dry laminating or wet laminating can be used.

[Action]

When the product is enclosed in the container of the present invention and the lid member is heat-sealed, the container can be easily opened by the following operation.

For example, in FIG. 1, when the knob portion 9 is lifted upward, peeling occurs between the innermost layer 1 of the multilayer container body and the layer 2 in contact therewith, and the peeling of the innermost layer reaches the cutting line 7,
The innermost layer is cut at the cutting line, and the lid member is peeled off. Further, since the peeling is possible even if the peel strength of the heat seal is increased, the container has excellent pressure resistance and heat resistance that can withstand boiling and retort treatment.

Further, since the heat non-fusion layer is provided, when heat sealing the lid member and the multilayer container main body, the length of t can be made constant, and the heat sealing work can be performed extremely easily.

Further, because of the heat-non-fusion layer, a cutting line can be formed at the same time as the heat-sealing of the lid material, or even after the heat-sealing, and it is possible to adopt a packaging form which does not change from the conventional one.

〔Example〕

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 The following multilayer sheet was formed by coextrusion.

Inner layer: High-density polyethylene resin layer 70 μm [Idemitsu Petrochemical Co., Ltd., Idemitsu Polyech 440M, density 0.96 g / cm
³ , MI 0.9 g / 10 min, small molecular weight distribution] Outer layer: polypropylene resin layer 200 μm polypropylene [Idemitsu Petrochemical Co., Ltd. Idemitsu Polypro E-10
0G, MI 0.6 g / 10 min] 80% by weight and low density polyethylene resin [Toyo Soda Industry Co., Ltd., Petrosene 1
72, density 0.92 g / cm ³ , MI 0.3 g / 10 min] 15% by weight and high density polyethylene resin [Idemitsu Petrochemical Co., Ltd. Idemitsu Polyethylene 530B] 5% by weight Mixture of 60 mmφ from this sheet by vacuum and pressure molding X40
A multilayer container body with a mm (height) flange was molded. On the inside of the flange portion of this multilayer container body, a thermal non-fusion layer of silicone resin as shown in FIG. 2 was provided. The multi-layer container body is covered with a lid material made of oriented nylon / polyvinylidene chloride / linear low-density polyethylene (15 μ / 20 μ / 40 μ), and a heat seal ring (t = 3 mm, extrusion ring width 1 mm) is used. Temperature 170-190 ℃, Pressure 2kgf /
A pressing line was formed by pressing at cm ² for 1 second.

When the lid material was peeled off from the container thus formed, it was peeled off between the layers of the multilayer sheet of the multilayer container body, and then the innermost layer of the multilayer container body was cut at the cutting line, which could be easily opened. Also, the opening force was stable.

〔The invention's effect〕

The present invention has excellent features such as high sealing strength, excellent sealing property, easy opening, stable opening force, good heat resistance, and boil or retort treatment. It is possible to obtain an easily openable container which has the practical value thereof.

[Brief description of drawings]

FIG. 1 (a) is a partial cross-sectional view of an embodiment of the easy-open container of the present invention, and FIG. 1 (b) is a view of peeling the lid material of the easy-open container shown in FIG. 1 (a). 2 is a partial sectional view showing
Drawing (a) and Drawing 2 (b) are sectional explanatory views showing an example of formation of a cutting line of an easy-open container of the present invention, and Drawing 3 is an outer edge of a flange part of an easy-open container of the present invention. FIG. 4 is a cross-sectional view of an embodiment in which a rib is provided on the portion, and FIG. 4 is a partial cross-sectional view of the easily openable container previously proposed by the applicant. In the figure, reference numeral 1 is the innermost layer of the multilayer container body, 2 is a layer in contact with the innermost layer of the multilayer container body, 3 is a flange portion, 4 and 5 are lid members, 6 is a heat seal portion, 7 is a cutting line, and 8 is A heat non-fusion layer, 9 is a knob portion, 10 is a heat seal ring, 11 is a seal portion, 12 is an annular body, 13 is a rib, and 14 is a cutting line.

Claims (1)

[Claims] 1. A container comprising a multi-layer container body and a lid member which is heat-sealed at a flange portion of the multi-layer container body,
The multi-layer container main body is configured to have an interlayer adhesive force smaller than an adhesive force between the flange portion and the lid member, and at least one of the flange portion and the lid member inside the heat seal portion is not thermally fused. And an annular cutting line provided inside the heat-sealing portion of the flange portion.