JPS63307073A - Easy-openable package and production thereof - Google Patents

Abstract

PURPOSE:To enhance sealing performance and openability while making the seal layer of the end part of a seal part thin, by making the interlayer release strength of a multilayer material lower than heat-sealing strength and forming a recessed seal layer to the inside end of the heat seal part of the multilayer material through other resin material layer. CONSTITUTION:The interlayer bonding strength of the multilayer sheet constituting a container main body is made lower than the heat-sealing strength of a resin material layer and a multilayer material and, when a lid material 4 is released, release is generated between the layers of the multilayer material to make the opening of the lid material 4 easy. The multilayer container main body and the lid material 4 are heat-sealed in a hardly released state at a flange part 3. Recessed seal parts 6, 7 are formed to the inside and outside ends of a heat-seal part 5. When a tab part 8 is raised, release is started between the innermost layer 1 and the layer 2 brought into contact therewith from the part of the recessed seal layer 7 and, in succession thereto, the innermost layer of the outer edge of the heat-seal part is cut and release advances between the innermost layer 1 and the layer 2 brought into contact therewith and the innermost layer is released up to the part of the recessed seal part 6 to release the lid material. Therefore, the lid material 4 and the multilayer material is good in sealing performance performance and the container can be easily opened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an easy-to-open package and a method for manufacturing the same. More specifically, the present invention provides an easy-to-open package that can be firmly heat-sealed and has excellent sealing properties, and is suitable for packaging foods, beverages, etc., particularly for heat-sterilized packaging. and its manufacturing method.

[Conventional technology]

Conventionally, for packaging foods, etc., contents are filled between two sets of resin materials, and then the two are sealed by heat sealing. However, when the heat-sealed package formed in this way is made to have high sealing strength by increasing the heat-sealing strength, it is difficult to open the package when the contents are used, and it becomes necessary to open the package with a knife. If you select a material with appropriate interlayer adhesion to improve unsealability, the sealing performance will vary greatly depending on heat sealing conditions such as temperature, pressure, and time, as well as contaminants such as fillers, making it difficult to obtain a certain level of adhesion. Since the sealing performance deteriorates, there is a problem in that it cannot be used particularly in packaging where the internal pressure is high, such as in retorts, etc., which are subjected to heat sterilization.

In order to solve this problem, Japanese Patent Application Laid-Open No. 61-190461
The publication describes a method of selecting a resin with appropriate internal cohesive strength as the sealing layer resin and achieving easy opening by utilizing cohesive failure of the sealing layer resin, but the sealing layer resin is limited. There is also the problem that the peeling surface is messy.

Furthermore, in JP-A-61-193848, a combination of a multilayer material consisting of an ethylene-vinyl acetate copolymer and an ionomer and a resin material consisting of an ionomer is selected as the resin material, heat-sealed, and the seal is easy to open. However, since the seal must be torn and opened, the combination of resin materials is limited to the above, and the opening side and the remaining side cannot be cut cleanly due to tearing and opening. There is a problem that it is aesthetically inferior.

Furthermore, Japanese Patent Application Laid-Open No. 54-143388 discloses that at least one of the resin materials to be heat-sealed is provided with a resin printed layer that is easy to break.
Publication No. 03372 describes a method of providing a releasable printed layer on at least one of the resin materials to be heat-sealed to facilitate peeling of the resin material and achieve easy opening, but both methods require a printing process. In addition, the process is complicated because it is necessary to match the printing part and the seal part, so it is not common.

Furthermore, Japanese Utility Model Application Publication No. 60-146077 describes a method of heat-sealing a lid material to a multi-layer container by penetrating the innermost layer of the multi-layer container to achieve easy opening. Since peeling occurs between the lid material and the innermost layer of the multilayer container, there is a problem that the opening force is not stable depending on the heat sealing conditions.

[Problem that the invention seeks to solve]

The present invention utilizes the glabellar peeling of a heat-sealed multilayer material to open the package, and thins the seal layer at the end of the sealed portion, thereby providing an easy-to-open package that has excellent sealing performance and excellent unsealability. It is.

[Means for solving problems]

That is, the present invention provides a package formed by heat-sealing a set of resin material layers, at least one of which is a multilayer material, in which the delamination strength of the multilayer material is made smaller than the heat sealing strength, and the heat sealing of the multilayer material is A concave sealing layer is press-formed on the inner edge of the part through another resin material layer, and such an easy-to-open package includes, for example, a pair of sealing layers, at least one of which is made of a multilayer material. The resin material layer can be manufactured by heat-sealing the resin material layer using a seal ring having a convex portion at least on the inner peripheral edge.

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a cross-sectional explanatory diagram illustrating the easy-to-open package of the present invention and its manufacturing method, and illustrates the case where the present invention is applied to a package formed by heat-sealing a multilayer container and a lid. be.

In Fig. 1, l is the innermost layer of the multilayer container main body, 2 is the layer in contact with this (outer layer), 3 is the flange portion, which is filled with the contents, and then covered with a lid material 4, and this lid material is The innermost N1 of the container body and the flange portion 3 are tightly heat-sealed. 5 indicates the position of the heat-sealed portion, and the multilayer container main body and the lid material are heat-sealed with difficulty in peeling at the flange portion of the multilayer container main body. A concave sealing layer 6.7 is formed at the inner and outer ends of the heat-sealed portion. A seal ring 9 is used to press the seal layer through the lid material to form a concave seal layer. The concave seal N7 at the outer end of the heat-sealed portion is intended to facilitate the peeling of the innermost layer of the multilayer container main body when unsealing, and is not necessarily necessary if peeling of the innermost layer of the multilayer container is started by other means. The concave sealing layer 6 at the inner end of the lid is necessary for cutting and opening the innermost layer that has been peeled off together with the lid. In any case, it is preferable for the concave seal layer that the tip of the concave portion is in contact with the layer (outer layer) that is in contact with the innermost layer of the multilayer container, from the viewpoint of releasability of the innermost layer.

The seal ring is provided with a convex portion 10 having a height of usually 10 to 500 μm, preferably 20 to 300 μm, on the periphery. A concave sealing layer is formed on the outer edge. As shown in FIG. 1, the heat-seal ring is not particularly limited as long as it has a convex portion on the peripheral edge and can form a concave sealing layer at the end of the heat-sealed portion.

FIG. 2 shows another preferred embodiment of the heat seal ring used in the present invention, in which a concave portion is formed near the convex portion of the inner peripheral edge of the heat seal ring, and a concave portion is formed at the inner edge of the heat seal portion. A non-heat-sealed portion is formed outward from the sealing layer, usually 1 to 10 mm, preferably 1.5 to 5 mm. Reference numeral 11 indicates the position of this non-heat-sealed portion.

FIG. 3 shows another embodiment of the present invention, in which the flange portion of the multilayer container is heat-sealed to the outer end, and no outer concave seal portion is provided.

Figure 2 is a plan view showing a preferred embodiment of the shape of the heat-sealed portion of the present invention. , which makes opening even easier.

The concave seal layer 6 is for cutting the innermost layer of the multilayer container body at the inner periphery of the flange when the lid material is peeled off, and this concave seal layer allows the innermost layer to be easily cut when the lid material is peeled off. Any type of sealing layer may be used, and the concave sealing layer may be provided in an annular shape such as a circle, a triangle, or a square over the entire inner periphery of the flange, or a portion may be left. If the cover material is to be peeled off with part of it still attached, do not provide a concave sealing layer only in that part.

The shape of the multilayer container main body in the easy-to-open color 7 package of the present invention is not particularly limited, but is usually circular, square, etc., and the lid material is heat-sealed in an annular shape along the flange portion of this shape. be done. Moreover, it may be cup-shaped or tray-shaped, and ribs or curls may be provided on the periphery of the flange portion.

Although the case where the multilayer material is a multilayer container in the package of the present invention has been described above, the present invention can also be applied to a case where the multilayer material is sheet-shaped and the package is bag-shaped.

Next, the other resin material (which becomes the lid material in the case of a multilayer container) may be a single layer film or a multilayer film, and is not particularly limited. When using a multilayer film, a base material made of a plastic single-layer film, multilayer film, paper, aluminum foil, or a composite material thereof, and a base material made of polyethylene, polypropylene, ethylene-α-olefin copolymer, ethylene - A sealant layer made of a resin that is easily heat-sealable to the innermost layer of a multilayer material made of a vinyl acetate copolymer or the like is preferably used.

To explain the multilayer structure of the multilayer material, the interlayer adhesive strength of the multilayer sheet is smaller than the heat seal strength between the resin material layer and the multilayer material, and when the resin material layer is peeled off, the multilayer material peels between the eyebrows and the lid material is opened. There is no particular restriction as long as the delamination is easy, but the delamination strength of this multilayer material is 200
~1500g/15mm (tensile speed 300 m/m i
n, the same applies hereinafter), preferably 300 to 1200 g/1
It is approximately 5W, and may be appropriately determined depending on the field of use of the package. The thickness of the innermost layer of the heat-sealed part of the multilayer material is usually 5 to 150 μm, preferably 10 to 100 μm.
It is.

There are no particular restrictions on the material for such multilayer materials;
Polyolefin resin, polystyrene resin, polyamide resin, polyester resin, polycarbonate resin, a mixture thereof, or a thermoplastic elastomer, various additives, or inorganic filler to these resins.
There are resins and metal foils containing 701i in an amount of %. Depending on the combination of layers made of these materials, materials suitable for the desired peel strength may be selected.

The innermost layer material and the outer layer material are the outer layer material and resin material 1' because it is easy to form a concave sealing layer. (lid material) heat-resistant temperature (
It is preferable to use a material whose melting point, softening point, etc.) is higher than that of the innermost layer material.

Preferred combinations of the innermost layer material (A) and the outer layer material (B) include, for example, the following combinations.

(A) polyethylene resin such as high-density polyethylene and low-density polyethylene, (B) mixed resin of polypropylene resin and polyethylene resin, (A) low-density polyethylene and (B) high-density polyethylene resin, (A) ethylene-vinyl acetate co-existence Polymer and (B) mixed resin of polypropylene resin and polyethylene resin, (A) mixed resin of ethylene-vinyl acetate copolymer and (B) ethylene-propylene random copolymer resin, (A) mixed resin of polypropylene resin and polyethylene resin Mixed resin and (B) mixed resin of inorganic filler-containing polypropylene resin and polyethylene resin, (A) mixed resin of polypropylene resin and polyethylene resin and (B) inorganic filler-containing high-density polyethylene resin, (A) random polymerized polypropylene resin and ( B) High-density polyethylene resin containing inorganic filler, (A) unsaturated carboxylic acid-modified polypropylene resin, and (B) aluminum. The multilayer material of the present invention may be a two-layer material made of the above-mentioned materials, but gas barrier properties A multi-layer material with three or more layers of other materials may be used for the purpose of improving the water resistance and reducing deformation when used as a container. - Examples include those with excellent gas barrier properties such as resin layers such as -vinyl alcohol co-11 combination, polyvinylidene chloride, nylon, and polyethylene terephthalate, and aluminum vapor-deposited layers.The layer made of these other materials may be only IF! However, it may be a multilayer body consisting of two or more layers, or it may include a resin layer containing 10 to 80% by weight of an inorganic filler.

The layer configuration of the multilayer material is appropriately selected depending on the sealant layer resin of the resin material layer (lid material). For example, when the resin material layer is a polyethylene sealant layer, in the above combination of resin layers, the high density polyethylene layer is preferably the innermost layer of the multilayer material.

In addition, in the easy-to-open package of the present invention, as long as the multilayer material has the feature of the present invention of having a peelable M layer, other layers such as a sealing layer may be added inside the innermost layer of the multilayer material as necessary. It may have. This container can be obtained by molding a coextruded multilayer sheet or a laminate sheet by vacuum forming, pressure forming, etc. using the combination of resins described above, or by multilayer injection molding, multilayer injection blow molding, multilayer blow molding, etc. can. Furthermore, it can also be obtained by thermoforming a multilayer film on the inside of a container such as paper.

As the lamination process, methods such as extrusion lamination, hot melt lamination, dry lamination, and wet lamination can be used.

[Effect]

A product is enclosed in the easy-to-open package of the present invention, and the resin material layer (
When opening a heat-sealed lid (lid material), you can easily open it by following the steps below.

For example, in FIG. 1, the knob 8 is lifted upward. Then, peeling starts between the innermost layer 1 and the layer 2 in contact with it from the concave sealing part 7, and then 8% of the innermost layer outside the heat-sealed part is cut, and as it goes, the innermost layer 1 and this layer are separated. Peeling progresses between the layers 2 that are in contact with the innermost layer, and the innermost layer is peeled off until the concave seal portion 6 is reached, and the lid material is peeled off. Therefore, even if the resin material layer (lid material) and the multilayer material are heat-sealed with good sealing properties and are difficult to peel off, the seal can be easily opened. Further, sealing conditions such as seal width can be freely set, and even if the seal is misaligned, ease of opening will not be impaired.

As a result, it is easy to open and can be peeled off even if the peel strength of the heat seal is increased.
This provides an excellent easy-to-open package that can withstand retort processing. In particular, if the seal ring shown in FIG. 2 is used, the peel strength from the inside of the container will be much higher than the peel strength from the outside, making it useful as a food package to be subjected to boiling or retort processing. Moreover, the appearance of the peeled surface after opening is also beautiful.

〔Example〕

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

Example 1 The following multilayer sheet was formed by coextrusion molding.

Inner layer: High density polyethylene resin layer 70μm [Idemitsu Petrochemical ■, Idemitsu polyethylene 440M, density 0.96g
/aa%Ml 0.9g/10min, molecular weight distribution small] Outer layer: Polypropylene resin layer 500μm Polypropylene [Idemitsu Petrochemical ■ Idemitsu Polypro E-1000,
Ml 0.6 g/10 min] 80% by weight and low density polyethylene resin [Toyo Soda Kogyo ■, Petrocene 172, density 0.92 g/al, M 10.3 g/10 min]
A mixture of 15% by weight and 5% by weight of high-density polyethylene resin (Idemitsu Polyethylene 530B manufactured by Idemitsu Petrochemical Co., Ltd.).

From this sheet, by vacuum and pressure forming, 60m1φ×4
A multilayer container with a flange of 0n (height) was molded.

As a lid material for this container, oriented nylon/polyvinylidene chloride/linear low density polyethylene (15 μ/20 μ/4
0μ)] and using a heat seal ring at the flange, the temperature was 180℃ and the pressure was 2K.
Heat sealing was performed at g/aJ. Note that a 40 μm annular convex portion was provided on the inner peripheral edge of the seal ring, and heat sealing was performed up to the outer end of the flange portion. The thickness of the inner end of the concave container sealing layer obtained by heat sealing (the thickness of the container inner layer) was substantially zero.

When the lid material of the thus obtained sealed container was peeled off, the container layers at the flange part were separated, and the innermost layer of the container was cut at the inner end of the sealing part and could be easily opened.

〔Effect of the invention〕

The present invention provides an easy-to-open package that has excellent characteristics such as high seal strength (high sealing performance, easy opening, good appearance on the peeling surface, and the ability to be boiled or retorted). In addition, it is easy to manufacture as it only requires sealing with a heat seal ring, and no special equipment is required. The practical value of the present invention is extremely large because the seal width is not limited (and the seal width can be set arbitrarily).

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional explanatory view showing heat sealing in one embodiment of the easy-to-open package of the present invention, and FIGS. 2 and 3 show other easy-to-open packages of the present invention. FIG. 4, a partial cross-sectional view of the embodiment, is a plan view showing a preferred shape of the heat-sealed portion. In the figure, numeral 1 is the innermost layer of the multilayer material, 2. 3 is a flange portion, 4 is a lid member, 5 is a heat seal portion, 6 and 7 are concave sealing layers, 8 is a knob portion, 9 is a seal ring, and 10 is a convex portion.

Claims (1)

[Claims] 1. In a package formed by heat-sealing a set of resin material layers, at least one of which is a multilayer material, the interlayer peel strength of the multilayer material is made smaller than the heat sealing strength, and the multilayer material An easy-to-open package characterized in that a concave sealing layer is press-formed on the inner end of the heat-sealed part through another resin material layer. 2. The easy-open package according to claim 1, wherein the multilayer material is a multilayer container. 3. A method for producing an easy-to-open package, characterized in that a set of resin material layers, at least one of which is a multilayer material, is heat-sealed using a seal ring having a convex portion on at least the inner peripheral edge. 4. The method for producing an easy-to-open package according to claim 3, wherein the multilayer material is a multilayer container.