JPH01294466A - Easy open container - Google Patents

Abstract

PURPOSE:To allow the title container to withstand not only an increase in the internal pressure thereof at the time of retort sterilization but also a falling shock and to hold the release strength from the outside of the container to easy open heat seal strength, by increasing the release strength from the center of the container. CONSTITUTION:A container is constituted of a container main body 2 having a heat- sealable flange 1 and a lid 3. A multilayer intermediate material 7 having a hardly cuttable layer 4 on one surface side thereof, a easily cuttable layer 5 on the other surface side thereof and an easily releasable interface or easily coagulable destructive layer 6 between both layers is provided between the flange 1 and the lid 3. A tight seal part 8a is formed between the intermediate material 7 and the lid 3 while a tight seal part 8b is formed between the intermediate material 7 and the flange 1. The inner peripheral side end edge 9 of the tight seal part 8b is positioned on the center side from the inner peripheral side end edge 10 of the tight seal part 8a and the outer peripheral side a d the outer peripheral side end edge 12 thereof is positioned at the same position as the outer peripheral side end edge 13 of said tight seal part 8a or on the center side therefrom and large release strength or breaking strength is obtained against the release or breaking force from the inside and the release from the outside is generated by small force.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an easy-to-open container, and more specifically, the peel strength from the inside of the container increases due to an increase in internal pressure during retort sterilization, for example. The present invention relates to an easy-to-open container that is large enough to withstand drop impact, etc., and whose peel strength from the outside of the container is maintained at an easy-to-open seal strength so that it can be opened by hand.

(Prior art) Conventionally, heat-sealed packaging bodies have been widely used in many fields of food packaging, and in particular, those that can be peeled off at the heat-sealed interface are widely used as easy-to-open or retractable heat-sealed lids. It is used.

Among heat-sealed packages, the seal strength of the heat-sealed part is 2.3 for those whose contents have been subjected to retort sterilization treatment.
kg/width of 15 mm or more, and when the sealing strength between the container body and the lid reaches this value, it becomes difficult to manually peel off the heat-sealed interface between the two.

To solve this problem, a heat-sealable inner material layer is provided on the inner surface of the container body, and the inner layer and the inner layer are easily peelable, and this layer is placed closer to the center than the heat-sealed part. A score is provided to cut the inner material layer, and the heat seal strength from the center to the outside is 2.3Kg715mm.
A heat-sealed container has already been proposed that has a medium-sized container that can be opened easily from the outside.

Further, the container is a container in which opposing parts of the container material and the lid material are sealed by heat sealing, an intermediate material is provided between the container material and the lid material, and a tight seal is formed between the lid material and the intermediate material, There is an easy-to-open seal between the container material and the intermediate material,
There has also been proposed an easily openable hermetically sealed food container characterized in that the tight seal portion is located outside of the container than the easy openable seal portion.

(Problems to be Solved by the Invention) The above-mentioned easy-to-open heat-sealed container has a sealing strength of 2.
．． This is significant because it provides easy-opening properties to the package while maintaining the weight of 3Kg, 715mm or more, but the former easy-open heat-sealed container requires score processing on the container, etc. The problem is that manufacturing is restricted.

In addition, in order to score the inside of the peripheral area for heat sealing, there are restrictions on the container material that can be used, and the area of the container flange inevitably becomes larger, which increases the amount of container material used and reduces the packaging material. It is also unfavorable from the viewpoint of increased bulk and appearance characteristics.

Furthermore, although the latter easy-to-open sealed container is suitable for solving the above-mentioned problems, it has the disadvantage that the heat-sealing strength depends on the heat-sealing conditions.

Therefore, an object of the present invention is to have a high peel strength from the center side of the container, for example, 2.3 kg 715 mm or more, so that it can withstand the increase in internal pressure during retort sterilization and the impact of dropping. Another object of the present invention is to provide an easy-to-open container in which the peel strength from the outside of the container is maintained at the easy-to-open heat-seal strength.

Another object of the present invention is to provide an easy-to-open container in which the above-mentioned peel strength anisotropy does not leave a score on the container or container lid, and the heat seal strength is not influenced by heat seal conditions. It is about providing.

(Means for Solving the Problems) According to the present invention, in a container in which opposing portions of a plurality of container materials are sealed by heat sealing, at least an unsealing start portion of the sealed portions is connected to the plurality of container materials. It has a laminated structure with an intermediate material inserted between them, and the intermediate material has a hard-to-cut layer on one side, an easy-to-cut layer on the other side, and an easily peelable interface or easy cohesive failure between the two. The inner edge of the seal between the easily cuttable layer and one container material is located closer to the center than the inner edge of the other seal, and There is provided an easily openable container characterized in that the outer edge of the former seal part is located at the same position as the outer edge of the latter seal part or closer to the center.

According to the present invention, in a container in which opposing portions of a plurality of container materials are sealed by heat sealing, at least an opening initiation portion of the sealing portions is connected to the plurality of container materials and an intermediate material inserted therebetween. The intermediate material has a laminated structure, and the intermediate material is a multilayer intermediate material having a hard-to-cut layer on both sides and an easily peelable interface or an easily cohesive failure layer between the two surfaces, and the inner edge of the intermediate material has a hard-to-cut layer on both sides. Provided is an easy-to-open container characterized in that the intermediate member is located closer to the center than the inner edge of the seal portion, and the outer edge of the intermediate member is at the same position as the outer edge of both seal portions at the opening start position. Ru.

(Function) In FIG. 1 showing an example of the container of the present invention, this container is composed of a container body 2 having a flange 1 for a heat sheet 1 and a lid 3. Between the flange 1 and the lid 3, there is a hard-to-cut layer 4 on one surface, an easy-to-cut layer 5 on the other surface, and an easily peelable interface or an easily cohesive failure layer 6 between the two. A multilayer intermediate material 7 is provided. In the specific example shown in FIG. 1, a tight seal portion 8a is formed between the intermediate material 7 and the lid 3, and a tight seal portion 8b is formed between the intermediate material 7 and the flange l.

The inner peripheral edge 9 of the tight seal portion 8b is located closer to the center than the inner peripheral edge IO of the tight seal portion 8a. Further, at the opening start position 11, the outer peripheral edge 12 of the tight seal portion 8b is connected to the outer edge 13 of the tight seal portion 8a.
It is located at the same position as or towards the center. In FIG. 2, which shows a state in which the internal pressure of the container is acting on this sealing part, the lid 3 is lifted upward from the center side to the outside, and a peeling force or breaking force P is applied to the sealing part from the center side to the outside.
acts. In this case, the inner circumferential edge 9 of the tight seal portion 8b between the multilayer intermediate material and the flange 1 is more centered than the inner circumferential edge lO of the tight seal portion 8b between the multilayer intermediate material and the lid 3. Therefore, even if the lid 3 is lifted upward, the multilayer intermediate material remains bonded to the flange l, and eventually the peeling force or breaking force P is concentrated on the inner peripheral edge 10 of the tight seal portion 8a. I will do it. However, the tight seal portion 8a naturally has sufficient peel strength to withstand peeling, and since the tight seal with the multilayer intermediate material is also performed on the surface of the hard-to-cut layer 4, it is difficult to cut. A large peel strength or breaking strength of, for example, 2.3 Kg or more for a width of 715 mm can be obtained against a peeling force or breaking force from the inside without breaking the adhesive layer.

On the other hand, in FIG. 3, which shows a state in which a peeling force from the outside is applied to the unsealing starting part 11 of the sealing part, when the end part 14 of the lid 3 is grasped and pulled upward, the tight seal part 8b
The outer peripheral edge 12 of the tight seal portion 8a is located closer to the center than the outer peripheral edge 13 of the tight seal portion 8a or at the same position, and the tight seal portion 8b is also located on the easily cutable layer 5 side of the multilayer intermediate material. The tight seal portion 8a is made of a hard-to-cut layer 4 of a multilayer intermediate material.
Since the peeling force P' is provided on the side, the peeling force P' is concentrated on the easily cuttable layer 5 at the position of the outer peripheral edge 12 of the tight seal portion 8b, and first the easily cuttable layer 5 is cut, and then the easily peelable interface Alternatively, interfacial peeling or cohesive failure in the easily cohesive failure layer 6 progresses, making it easy to open the package by hand. Of course, the cutting of the easily cuttable layer 5 and the peeling of the layer 6 are carried out at a rate of, for example, 2 Kg/l.
It is natural that this occurs with a relatively small force of less than 5 mn+width.

In the heat-sealed structure shown in FIG.
A part or more of the layer 6, which is susceptible to cohesive failure, remains.

In FIG. 4, which shows another aspect of the invention, the container is
It has the same layered structure as the container described above, and is composed of a container body 2 having a heat sealing flange 1 and a lid 3.

Between the flange 1 and the lid 3, there is a hard-to-cut layer 4 on both sides.
, and a multilayer intermediate material 7 having an easily peelable interface or an easily cohesive failure layer 6 between the two. In the specific example shown in FIG. 4, a tight seal portion 8a is formed between the intermediate material 7 and the lid 3, and a tight seal portion 8b is formed between the intermediate material 7 and the flange 1. Inner peripheral side edges 9 of both tight seal portions 8a, 8b. lO is located outside the inner peripheral edge 15 of the multilayer intermediate material 7.

Also, both tight seal portions 8a, 8 at the opening start position.
The outer peripheral edges 12 and 13 of b are located at the same position as the outer peripheral edge 16 of the multilayer intermediate material 7. That is, in the specific example shown in FIG. 4, all the outer circumferential edges including the intermediate material are regulated at the same position over the entire circumference. This ensures that the lid and container are in close contact even on the outer periphery, and prevents the lid from turning over at the edges.

In FIG. 5, which shows a state in which a peeling force or a destructive force is applied from the inside to this sealing portion, the inner circumferential edge 15 of the multilayer intermediate material 7 is attached to the inner side of both tight sealing portions, for example, 8a and 8b. Edge 9. Since it is located closer to the center than IO and extends toward the center in a free state from both tight seal parts 8a and 8b, even if internal pressure acts on the lid 3 and M3 is lifted upward, , the peeling force or breaking force at this time does not act on the easily peelable interface or the easily cohesive failure layer 6 at the inner peripheral edge 15 of the multilayer intermediate material 7, and the inner peripheral edge lO of the tight seal portion 8a Or, it concentrates on the inner circumferential edge 9 of the tight seal portion 8b. Since the seal portions of both tight seal portions 8a and 8b are strong, and both of these tight seals are formed between the hard-to-cut layer 4,
For the same reasons as mentioned in relation to Figure 2, for example:
A large peel strength or breaking strength of 2.3 g/15 cm width or more can be obtained.

On the other hand, in FIG. 6, which shows a state in which a peeling force from the outside is applied to the unsealing start part 11 of the sealing part, when the end part 14 of the lid 3 is held and pulled upward, the tight seal part 8b
, the tight seal portion 8a and the outer peripheral edge of the intermediate material 7 are all at the same position, so this peeling force P° is concentrated on the easily peelable interface of the intermediate material 7 or the layer 6 that is easily cohesively fractured. This results in a peel strength of, for example, 2 Kg/15 mm width or less, making it easy to peel and open the package by hand.

The intermediate material 7 may be provided around the entire circumference of the sealed portion, but the opening starting portion 1
It may be only 1. When opening, the opening strength is greatest at the part where the peeling is widest in the sealed part, which is the opening start part 11 for fishing on a boat. Therefore, even if the combination of the container 2 and the lid 3 has a strong sealing strength, for example, 0 to 3 kg/15 mm width, the multilayer intermediate material 7 described above is inserted only into the opening start part IJ, and the lid is By forming a tight seal between 3 and flange 1 and regulating their position, the same effect as described above can be obtained, and the maximum value of the opening strength is reduced, making opening easier.

The easily openable sealed container of the present invention has the advantage that the heat sealing strength is not affected by heat sealing conditions. For heat sealing, for example, high frequency induction heating can be used as a power source, and a high frequency of 10 KHz to 50 Mlfz can be used, and the pressure during heat sealing is 0.5 to 5 kHz.
Kg/cm2, and the heating temperature of the heat-sealing surface is above the melting point of the resin and below its thermal deterioration temperature. ing.

In conventional easy-open containers, one layer close to the heat-sealing surface forms a tight seal and the other layer forms an easy-open seal, and when heat-sealing conditions suitable for either one are adopted, The disadvantage is that the peel strength may be weak or too strong. However, according to the layer structure of the heat-sealed portion of the easy-to-open container of the present invention, both the amphoteric layers close to the heat-sealed surface form a tight-sealed portion, and the easy-to-open layer is located inside. In addition, even if heat sealing is performed under conditions such as heat sealing temperature and pressure suitable for the tight seal layer close to the heat sealing surface, the easy open layer inside is not easily affected by this, and easy openability may be impaired. Therefore, the peel strength from the inside of the container is high enough to withstand retort sterilization, and the peel strength from the outside of the container is maintained at an easy-to-open seal strength that can be opened by hand.

(Description of Preferred Embodiments) In the present invention, forming a difficult-to-cut layer or an easy-to-cut layer in the intermediate material is accomplished most simply by changing the thickness of each layer. For example, in the case of resins such as isotactic polypropylene or high-density polyethylene, the thickness should be 20 μm or more, preferably 30 μm.
With the above configuration, a hard-to-cut layer can be obtained. On the other hand, in order to obtain an easily cuttable layer, the thickness should be 15 μm or less, preferably 10 μm or less. Another method for forming the easily cuttable layer is to form the easily cuttable layer to such an extent that peeling at the time of opening does not result in interface failure between the easily cuttable layer and the container material bonded to this layer, or to such an extent as not to cause cohesive failure of this layer. Other resins or inorganic fillers may be blended into the easily cuttable layer.

In addition, in order to form an easily peelable interface or an easily cohesive failure layer between the hard-to-cut layer and the easy-to-cut layer, or between the hard-to-cut layer and the hard-to-cut layer, each The adhesion between the layers or the cohesive force of the layer that should become a layer that can easily fail cohesively is utilized. For example, one of the hard-to-cut layer and the easy-to-cut layer is an isotactic polypropylene layer, a crystalline propylene-ethylene random copolymer, and 15% by weight of low-density polyethylene.
By forming a two-layer system consisting of a blended layer of about 30% by weight and the other layer being a high-density polyethylene layer, an easily peelable interface is formed between the blend layer and the high-density polyethylene layer. In addition, by replacing the high-density polyethylene layer with a crystalline propylene/ethylene random copolymer and further blending 1 to 5% by weight of ethylene/propylene rubber into the blend layer to increase the blending ratio of low-density polyethylene, It is possible to form an easily peelable interface between the tactical polypropylene layer and the blend layer, and to make the blend layer itself a layer that is prone to cohesive failure. Furthermore, when the blend layer is made of a modified polyolefin resin obtained by chemically modifying with a polymerizable resin, such as styrene-modified polypropylene, or when a blend layer of these resins and other resins is used. A similar effect can be obtained if These examples apply to heat-sealable resins such as other polyolefin resins, propylene/α-olefin copolymers, ethylene/α-olefin copolymers, polyesters, copolyesters, polyamides, and copolyamides.

A method for producing the intermediate material includes a method of coextrusion using a multilayer tie. Incidentally, a method of extrusion coating a necessary layer on a preformed base material may also be mentioned. However, in consideration of interlayer releasability and thickness structure of each layer, coextrusion is preferred.

It is also known that polyolefin films have heat-sealing properties for certain coating films. That is, a polyolefin film exhibits excellent heat-sealability compared to a coating film in which oxidized polyethylene or acid-modified olefin resin is dispersed. By providing this coating on the inner surface of the lid or container and adjusting the amount of dispersed polyethylene oxide or acid-modified olefin resin, a phytoseal is formed on one side of the polyolefin film and an easy-to-open seal is formed on the other side. I can do it. This tendency also applies to resins such as polyester and polyamide that exhibit heat sealability with paints.

The positions of the inner and outer edges of the easy-to-open seal portion and the inner and outer edges of the tight seal portion can be controlled by any means. Most simply, by regulating the shape and position of the heat seal head on the lid or container flange of the intermediate material, the positions of the inner and outer edges can be controlled.

Alternatively, a non-adhesive coating defining the inner and outer edges of the heat-sealed portion may be applied to the flange surface and inner surface of the lid by printing, coating, vapor deposition, welding, or other known thin film forming techniques. Alternatively, it can be applied to an intermediate material to regulate the position of the inner and outer edges of the heat-sealed portion.

Furthermore, as another method, in order to control the position in the opening start part 11, in the container shown in FIG.
By providing the intermediate material 7 so as to protrude outward from the flat part for heat sealing as shown in b) and (c),
During heat sealing, the positions of the outer edges of the tight seal parts 8a and 8b between the intermediate material 7, the lid 3, and the flange 1 can be easily controlled. In addition, in FIGS. 8(a) and 8(b), the outer periphery of the flange has an outer periphery recessed part 1 that is more recessed than the flat part 18.
7 is provided. In addition, in the container shown in FIG. 4, after the intermediate material 7 is bonded to the flange 1,
By cutting the flange 1 and the intermediate member 7 on the inner side of the edge at the same time, the outer edges of each are placed at the same position, thereby making it easier to regulate the position. Furthermore, FIGS. 8(b) and (C)
When the intermediate material is provided with a portion 19 protruding inward from the sealing flat portion of the flange as shown in the figure, and this protruding portion 19 of the intermediate material is heat-sealed to the container side,
The position of the inner edge of the tight seal portions 8a, 8b between the intermediate member 7, the lid 3, and the flange 1 can also be easily controlled.

The container body and lid may be made of any container-forming material known per se, such as resin, metal, paper, glass, ceramic, or a laminate thereof. Suitable container bodies and lids are made of a resin having heat-sealing properties at least on the inner surface, such as low- to medium-high density polyethylene, tactical polypropylene, propylene-ethylene copolymer, ethylene-vinyl acetate copolymer. Olefin resins such as olefin resins graft-modified with polymerized or ethylenically unsaturated carboxylic acids or their anhydrides: Coating films made by dispersing oxidized polyethylene or acid-modified polyolefin resins: Comparatively low melting point or low softening point Polyamide or copolyamide resin: Consists of polyester or copolyester resin having a relatively low melting point or low softening point. These resins or coatings may contain inorganic fillers.

The lid body is made of metal foil such as aluminum foil, tin foil, steel foil, or tin foil, high oxygen barrier resin film such as ethylene vinyl alcohol copolymer, vinylidene chloride resin, or nylon resin, biaxially oriented polyethylene terephthalate film, or biaxially oriented polyethylene terephthalate film. A thermoplastic resin film such as an axially stretched nylon film or a polycarbonate film, various compositions, or a laminate thereof may be used as a base material, and the above-mentioned heat-sealable resin layer may be laminated thereon as an inner material.

The intermediate material consists of a hard-to-cut layer on one side, an easy-to-cut layer on the other side, and an easy-to-peel interface or an easy-to-cohesive failure layer between the two, or a hard-to-cut layer on both sides. and a film having a layer structure consisting of an easily peelable interface or an easily cohesive failure layer between the two, the thickness of which must be at least resistant to breakage when the package is opened, -M is 15 to 1000 μm, In particular, a thickness in the range of 30 to 150 μm is desirable.

The present invention is particularly useful for applications in which the contents are sterilized by retort or boiling, or by hot filling.In this case, from the standpoint of heat resistance, the inner material of the container and lid may be made of polypropylene resin. is common. As an intermediate material particularly suitable for this application, the total thickness is between 20 and 1000 mm.
μm, especially in the range of 30 to 150 μm, the thickness of the hard-to-cut layer is 20 to 60 μm, the thickness of the easy-to-cut layer is 1 to 15 μm, and when the peeling is due to a cohesive failure layer, the thickness of this layer is 1 to 30 μm. It is desirable that it falls within the range of . Furthermore, the hard-to-cut layer is made of tactical polypropylene, the easy-to-cut layer is made of a crystalline propylene/ethylene random copolymer, and there is an easily peelable interface or The materials that themselves become a cohesive failure layer include 10 to 65% by weight of crystalline propylene/ethylene random copolymer, 34 to 89% by weight of low density polyethylene, and 1 to 1% by weight of ethylene/propylene rubber.
Examples include a three-layer coextruded film or a laminate film consisting of 10% by weight blended layers.

Although the present invention has been described above with respect to a sealed container consisting of a cup-shaped container and a lid, the present invention can also be applied to a container formed by sealing three pieces of pouch-constituting material around the circumference by heat sealing. In FIG. 7, which shows an example of this container, pouch constituent materials 2' and 2' are heat-sealed through an intermediate material 7, and tight seals 8a are formed on both sides of the intermediate material.

8b and the intermediate layer of intermediate material forms an easy-to-open seal. The positional relationship of the edges of these seal parts is the same as in the case of the container described above. The intermediate material may be provided around the entire circumference of the pouch, or may be provided only in the portion of the pouch that is to be opened.

(Effects of the Invention) According to the present invention, a multilayer intermediate material having a hard-to-cut layer on one side, an easy-to-cut layer on the other side, and an easily peelable interface or an easily cohesive failure layer between the two By providing tight seal portions on both sides of the container and regulating the positions of the inner and outer edges thereof, the container or the score is not engraved.

It becomes possible to provide a predetermined difference between the peel strength from the center side of the container and the peel strength from the outside of the container, thereby providing an easy-to-open container that can be opened by hand.

Further, according to the present invention, a constant peel strength can be obtained regardless of heat sealing conditions.

(Examples) Example 1 Specifications of the lid material, cup-shaped container, and intermediate material used in Example 1 are shown below.

A 70 μm crystalline propylene/ethylene random copolymer film (ethylene 3.6%) laminated with urethane adhesive.

40 μm on one side of a 75 μm surface-treated steel foil in a cup-shaped container and 7 μm on the other side.
A 0 μm unstretched polypropylene film was laminated with a urethane adhesive, and the laminate was deep drawn so that the 70 μm film side became the heat sealing surface.
A sentence-shaped container with an outer diameter of 75 mm and a flange for heat sealing.

An isotactic polypropylene layer (EA layer with an intermediate material of 44 μm) and a crystalline propylene/ethylene random copolymer (
Ethylene content: 3.6% by weight) and 48% by weight.
Propylene rubber (ethylene content 49% by weight) 2% by weight
and 50% by weight of low-density polyethylene [layer B], and a further 3μm of crystalline propylene/ethylene random copolymer (ethylene content 3.6%).
) layer [C layer].

A sealed container of the type shown in FIG. 1 was made using these lid materials, cup-shaped containers, and intermediate materials.

The intermediate material 7 was provided around the entire circumference of the heat sealing surface, and the intermediate material 7 protruded outward from the flange 1 by 3 mm. Heat sealing is performed by heat sealing 8b between the molded container 2 and the intermediate material C layer side 5.
was first performed, and after filling about 90% of the total volume with water, the intermediate material A layer side 4 and N3 were heat-sealed 8a to seal.

Note that the molded container 2 and the intermediate material C layer side 5 are heat-sealed 8.
b uses a Teflon-coated heat seal head,
The test was conducted at 180°C for 0.8 seconds. Further, the heat sealing part 8a between the intermediate material A layer side 4 and the lid 3 is a heat sealing part 8a.
The inner edge 10 of the molded container 2 and the side of the intermediate material C layer are positioned 1.5 mm outside the inner edge 9 of the heat-sealed portion 8b of the container, and the outer edge 13 is outside the flange. This was done by regulating the shape and position of the heat seal head. At this time, each heat seal portion 8a.

The width of the overlap of 8b was 3 mm. The heat sealing conditions were 200° C. for 1.5 seconds twice.

The sealing performance and unsealing performance of the thus obtained sealed and filled container were measured using a tensile tester after retort sterilization at 120°C for 30 minutes. To measure the sealing performance, cut out a 15 mm wide strip perpendicular to the direction of heat sealing, hold the lid side of the strip in the upper chuck and the side wall of the cup in the lower chuck, and move it up and down at a speed of 300 mm/min. I pulled it. In addition, the opening strength can be determined by fixing the container on a cross head at a 45° angle and holding the grip for opening the lid between the upper chuck (the angle between the top surface of the container and the grip of the lid is 45"). (state), and was pulled up and down at a speed of 300 mm/min.The peeling or breaking strength from the inside of the container was 3.
It had a width of 2Kgf/15mm and an opening strength of 1.5Kgf.

Example 2 and Comparative Example 1 The lid material used in Example 1 was a 12 gm biaxially stretched polyethylene terephthalate film, a 15 μm biaxially stretched nylon-6 film, and a 20 gm biaxially stretched polyethylene terephthalate film.
A 15 μm maleic anhydride-modified polypropylene layer and a crystalline propylene/ethylene random copolymer (ethylene content 3.6%) are attached to the aluminum side of the base material, which is made by laminating μm soft aluminum foil with a urethane adhesive. The intermediate material and cup-shaped container used in Example 1 were used instead of the packaging material coated with a 35-μm blend layer of 20% by weight of low-density polyethylene by co-extrusion, and the intermediate material 7 was replaced with the cup-shaped container 2. A sealed and filled container was produced under the same conditions as in Example 1 by applying it only to the opening start part 11 (Comparative Example 1). The sealing performance and unsealing performance of each sealed filled container were evaluated in the same manner as in Example 1.

In a container (Example 2) in which the intermediate material 7 was applied only to the opening start part 11 of the heat-sealed surface, the peeling or breaking strength from the inside of the container was 3.
．． The width was IKgf/15mm, and the width was 2.7Kgf/15mm in the part where intermediate material 7 was not applied, and the opening strength was 1.8Kgf. In addition, in a container that does not use the intermediate material 7 (Comparative Example 1), the peel strength from the inside of the container is 2.
The width was 8Kgf/15mm, and the opening strength was 4.3Kgf.

Example 3 The use of the lid material, cup-shaped container, and intermediate material used in Example 3 will be shown below.

Lid material The same lid material as used in Example 1.

Cup-shaped container A round container with an outer diameter of 77 mm and a heat-sealing flange with a width of 6 mm, made by vacuum forming an 800 μm polypropylene sheet.

An isotactic polypropylene layer (EA layer with an intermediate material of 40 μm) and a crystalline propylene/ethylene random copolymer (
48% by weight (ethylene content 3.6%), 2% by weight ethylene-propylene rubber (ethylene content 40%), and a further 15 μm crystalline propylene-ethylene random copolymer layer (ethylene content 3.6%). EC layer]
Layered coextruded film.

A sealed container of the type shown in FIG. 4 was produced using these lid materials, cup-shaped containers, and intermediate materials.

Intermediate material 7 was applied to the entire circumference of the heat-sealed surface. Heat sealing is performed first by heat sealing 8b between the molded container 2 and intermediate material C layer side 4b, and after filling approximately 90% of the total volume with water, heat sealing 8a between intermediate material A layer side 4a and lid 3. It was sealed by doing this.

The molded container 2 and the intermediate material C layer side 4b are heat-sealed using a Teflon-coated heat seal head.
The test was carried out at 5°C for 0.8 seconds. After heat-sealing, the intermediate material 7 and the flange l are trimmed all around so that the outer edges of the intermediate material 7, the heat-sealed part 4b, and the flange l are at the same position, and the outer diameter is reduced to 75 m.
It was set as m.

The shape and position of the heat seal head were controlled so that it overlapped with the A layer side 4a of the intermediate material by a width of 3 mm from the outside. At this time, the A layer side 4a of the intermediate material 7 and the lid 3
The inner edge lO of the heat-sealed portion 8a with the molded container 2
It was located 1.8 mm outside the container from the inner edge 9 of the heat-sealed portion 8b between the intermediate material C layer side 4b and the intermediate material C layer side 4b. The heat sealing conditions were 200° C. for 1.5 seconds twice.

The sealing performance and unsealing performance of the thus obtained sealed and filled container were evaluated in the same manner as in Example 1. The peeling or breaking strength from the inside of the container was 3.8 Kgf.

Note that in Examples 1, 2, and 3, the peeling was due to internal destruction of the intermediate material, and it was easy to open the package by hand, whereas in Comparative Example 1, it was difficult to open the package by hand.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a container according to the present invention. 2 is a diagram showing a state in which a peeling force is applied from the inside to the container shown in FIG. 1, and FIG. 3 is a diagram showing a state in which a peeling force is applied to the container shown in FIG. 1 from the outside. FIG. 4 is a diagram showing another example of the container of the present invention, and FIG. 5 is a diagram showing a state in which a peeling force is applied to the container shown in FIG. 4 from the inside. FIG. 6 is a diagram showing a state in which a peeling force is applied from the outside to the container shown in FIG. 4, and FIG. 7 shows another example of the container of the present invention. FIG. 8 is a diagram showing a preferred example of application of the intermediate material. 1... Flange for heat sealing, 2... Container body,
3... Lid, 4... Hard-to-cut layer, 5... Easy-to-cut layer, 6... Easy-to-peel interface or easy-to-cohesive failure layer, 7...
・Intermediate material, 8a, 8b...tight seal part, 9.10
... Outer circumference side edge, 12.13... Inner circumference side edge.

Claims (2)

[Claims] (1) In a container in which opposing portions of a plurality of container materials are sealed by heat sealing, at least the opening initiation portion of the sealing portions has a laminated structure of the plurality of container materials and an intermediate material inserted therebetween. The intermediate material is a multilayer intermediate material having a hard-to-cut layer on one surface, an easy-to-cut layer on the other surface, and an easily peelable interface or an easily cohesive failure layer between the two,
The inner edge of the seal between the easy-cut layer and one container material is located closer to the center than the inner edge of the other seal, and the outer edge of the former seal at the opening start position is An easy-to-open container characterized by being located at the same position as the outer edge of the latter seal part or at the center side. (2) In a container in which opposing portions of a plurality of container materials are sealed by heat sealing, at least the opening initiation portion of the sealing portions has a laminated structure of the plurality of container materials and an intermediate material inserted therebetween. The intermediate material is a multilayer intermediate material having a hard-to-cut layer on both sides and an easily peelable interface or an easily cohesive failure layer between the two surfaces, and the inner edge of the intermediate material is on the inside of both seal parts. An easy-to-open container characterized in that the intermediate material is located closer to the center than the edges, and the outer edge of the intermediate material is at the same position as the outer edges of both seal parts at the opening start position.