Easy-Open Packaging Body

This application is a Bypass Continuation of International Application No. PCT/JP2023/046007 filed Dec. 21, 2023, claiming priority based on Japanese Patent Application No. 2023-000621 filed Jan. 5, 2023, and JP 2023-193953 filed Nov. 14, 2023, the contents of all of which are incorporated herein by reference in their respective entireties.

The disclosure relates to an easy-open packaging body composed of a container including a flange portion, and a lid member that can be attached to the flange portion by heat sealing, and more specifically, to an easy-open packaging body with which the sealing position can be easily controlled, and the lid member can be attached by heat sealing with easy openability and sealability.

Resin containers in which a flexible lid member is heat-sealed to a flange portion are widely used as simple containers for food and beverages. In such resin containers, it is necessary to achieve the conflicting performances of high sealability and easy openability by means of heat sealing.

As a container addressing this requirement, for example, JP-A-2005-119692 discloses a multilayer container in which a flange portion is disposed around the periphery of an opening, at least one layer including the inner layer of the container is formed in a manner allowing peeling, two annular cuts are provided on the upper surface of the flange portion, and a portion lower than the upper surface of the flange portion is formed in connection with the outer one of the two annular cuts.

In JP-A-2005-119692, since a portion lower than the upper surface of the flange portion is formed, even if a seal ring is positioned on the outer lower portion, the lid member will not be heat-sealed at the outer portion of the flange portion due to the cut including the lower portion, or even if sealed, the sealing will be weak, thereby not impairing openability.

Japanese Patent No. 5878683 discloses an easy-open container including a container body including a flange portion at a periphery of an opening and formed from a layered body including at least a surface layer and an underlying layer, and a lid member including at least a seal layer capable of adhering to the surface layer, in which the surface layer of the flange portion and the seal layer of the lid member are annularly heat-sealed, and the lid member is made openable by cohesive failure occurring in at least one of the seal portion of the lid member and the container body, and a mound-shaped resin accumulation portion composed of the constituent resins of the surface layer and the underlying layer of the container body and the seal layer of the lid member is formed on the inner peripheral side of the seal portion on the flange portion, along the entire periphery of the opening, so as to satisfy the conditions represented by Equation (F1).

Japanese Patent No. 5878683 discloses that the lid member is opened by cohesive failure of the surface layer of the container body due to heat sealing of the lid member to the flange portion, thereby exhibiting excellent openability, and that high sealability is ensured by the formation of a resin accumulation composed of the constituent resins of the surface layer and the underlying layer of the container body and the seal layer of the lid member.

Further, in order to achieve both sealability and easy openability in containers with a flange, it has also been proposed to control the seal strength between the lid member and the flange portion. For example, JP-A-2013-100138 discloses a container in which the flange portion includes a flat portion where a seal portion is formed and an extended portion extending from the outer peripheral edge of the flat portion, in which the container body includes at least two layers including a seal layer and a base material layer; the seal layer has a thin portion or a missing portion on at least one of the outer peripheral side and the inner peripheral side of the flat portion, and has an easy-to-separate member on the other side; and in the flat portion, the thickness of the side having the thin portion or the missing portion is 20% to 98% relative to the thickness at the center.

JP-A-2013-100138 discloses that, by forming the flange portion that becomes thinner toward the inner edge, it is possible to eliminate the need for position control of the seal portion when sealing the lid member to the container body, thereby easily achieving both easy openability and sealability.

However, in JP-A-2005-119692, opening is started by pulling up the lid member, thereby causing stress concentration at the layer end portion between the inner layer and the adjacent layer of the container body, which poses a risk of unintentional opening during distribution or the like. Therefore, it is desirable to enable more reliable initiation of interlayer peeling at the time of opening. Further, since two annular cuts are provided on the upper surface of the flange portion, there is a concern that in containers with thin walls, a gas barrier layer or the like may be exposed, which makes it difficult to apply such barrier layers.

In addition, in Japanese Patent No. 5878683 described above, high sealability is achieved by forming a resin accumulation; however, since the lid member is peeled off by causing cohesive failure of the surface layer of the container during opening, a greater force is required compared to interlayer peeling, and thus the openability is still not fully satisfactory.

In addition, in the container described in JP-A-2013-100138, a tight seal that cannot be peeled off is formed between the lid member and the inclined surface of the flange portion. However, when severe sealing conditions occur, a resin accumulation containing the seal layer is formed on the inner edge side. If there is a large circumferential variation in the thickness of the flange, the areas with greater thickness are subjected to harsher sealing conditions. As a result, when the internal pressure increases and the lid is deformed into a dome shape, unintended interlayer peeling may start from the inner edge side of a thin sealing portion formed near the resin accumulation containing the seal layer, thus leading to a decrease in seal strength (burst strength). In addition, the burst strength significantly varies depending on the sealing temperature, and as a result product-to-product variation may result, which may complicate product management.

In addition, when the upper surface of the flange portion is formed as an inclined surface simultaneously with the formation of the flange portion, the mold processing becomes more complicated compared to the case where the upper surface of the flange portion is formed as a flat surface. As a result, the cost of mold production may be increased, which is also unsatisfactory in terms of economic efficiency.

An object of the disclosure is to provide an easy-open packaging body that has excellent sealability through heat sealing, and can be easily opened with a smaller opening force using a resin accumulation resulting from heat sealing.

Another object of the disclosure is to provide an easy-open packaging body with excellent sealability and easy openability that is applicable also to a thin container.

Still another object of the disclosure is to provide an easy-open packaging body capable of facilitating product management by reducing variations in burst strength even under the same sealing condition, or sealing conditions that are different in the circumferential direction.

An easy-open packaging body according to the disclosure includes: a container; and a lid member, the container including a flange portion at a periphery of an opening, and a surface seal layer formed at least on a top surface of the flange portion, the surface seal layer being joinable to the lid member and easy to peel off from a base material of the container, the lid member being configured to seal the container by joining to the surface seal layer of the flange portion, wherein in the flange portion, a side wall portion extending in a container axial direction is formed on an outer side of an outer peripheral edge of a joining position with the lid member, and the surface seal layer includes a resin accumulation protruding outward from the outer peripheral edge of the joining position, and a surface seal layer having a small thickness serving as an opening start portion on a lower or inner side of the resin accumulation.

Preferably, in the easy-open packaging body according to the disclosure,

The easy-open packaging body of the disclosure includes the resin accumulation protruding outward from the outer peripheral edge of the joining position of the lid member and the flange portion, and the thin surface seal layer serving as the opening start portion disposed on the lower or inner side of the resin accumulation. As a result, at the start of opening, the resin accumulations of the lid member and the container integrally move up with the lid member, and the thin surface seal layer adjacent to the interface with the base material layer that serves as the opening start portion can be easily fractured, thus easily causing interlayer peeling between the surface seal layer and the base material layer. In this manner, it can be opened without requiring a large opening force.

In addition, since a step portion or an inclined portion including a surface seal layer as thin as possible or no surface seal layer is provided on the outer circumference side of the joining position, it can be easily fractured and can provide excellent openability.

Further, since the lid member is firmly heat-sealed at the joining position, excellent sealability is ensured, and unintended opening is also prevented.

In addition, the first joining portion that is located on the outer peripheral edge side, and the second joining portion that is located on the inner peripheral edge side and is lower in height than the first joining portion in the container axial direction are formed at the joining position of the flange portion serving as the sealing position with the lid member, such that during the heat sealing, the pressure of the seal head is easily exerted on the first joining portion, while the pressure is less exerted on second joining portion. As a result, the resin accumulation composed of the container surface seal layer is easily formed on the outer side of the first joining portion in the radial direction, which is bonded to the resin accumulation composed of the lid member seal layer, thus improving easy openability. On the other hand, at the second joining portion, the resin accumulation composed of the container surface seal layer is less formed on the inner side of the second joining portion in the radial direction, that is, formation of the initiation point of the cohesive failure can be suppressed, and thus unintentional peeling from the inner side due to internal pressure increase can be effectively prevented.

In addition, in this aspect, since the resin accumulation composed of the container surface seal layer on the inner side of the second joining portion in the radial direction can be easily controlled as described above, it is possible to reduce variations in the strength (burst strength) that causes interlayer peeling from the inner side due to an increase in internal pressure, and to control the burst strength in accordance with the sealing temperature. Thus, it is possible to provide containers with stable quality, thereby facilitating product management.

Further, since the top surface of the joining portion is flat, the pressure received at the joining portion from the seal head during the heat sealing can be received by the entirety of the top surface of the joining portion, and the influence on the base material making up the container can be suppressed to prevent deformation of the base material. In addition, since the mold (locator) used for forming the first joining portion, the second joining portion and the coupling portion can be processed using a tool for forming a flat shape, the processing is easy and economical.

is a perspective view of an example of the container used in the disclosure,illustrates a layer structure,is a cross-sectional view illustrating an enlarged view of the flange portion of the container illustrated in, andis a cross-sectional view illustrating an enlarged view of the flange portion with a lid member heat-sealed to the container illustrated in.

In general, the container, the entirety of which is indicated by, includes a bottom portion, a barrel portion, a flange portionextending outward from the upper end of the barrel portionin the container radial direction, and an annular skirt portionextending downward from the outer peripheral edge of the flange portion. As is clear from, the containeris integrally molded from a layered body composed of a base material layerand a surface seal layersuch that the surface seal layeris the top surface located to face the lid member (not illustrated) at the flange portion.

Note that, the base material layerand the surface seal layerare formed of resin that is easy to peel off, thus allowing easy peeling between the base material layerand the surface seal layerwhen the lid member is opened, thus improving the openability.

As is clear from, at the top surface of the flange portion, an annular joining portion, which is the joining position (heat seal position) of the lid member, is formed at the center portion, and an outer step portionis formed on the outer side of the annular joining portion. In addition, in the specific example illustrated in, an inner step portionis formed with an inclined portiontherebetween on the inner side of the annular joining portion.

The outer step portionis lower than the axial height of the top surface of the annular joining portionby L, and a side wall portionserving as a step is formed between it and the annular joining portion. In the side wall portion, a surface seal layerthinner than a surface seal layerof the annular joining portionis formed. A grooveis formed at the boundary of the side wall portionand the outer step portion. Similarly, also in the outer step portion, a surface seal layerwith a thickness smaller than that of the surface seal layerof the annular joining portionis formed.

As illustrated in, the container is sealed by heat-sealing a lid memberto the annular joining portionof the flange portionof the container. As is clear from, the lid memberis composed of a base material layer, and a heat seal layercomposed of a heat-sealable resin that can be heat-sealed to the surface seal layerof the container.

As illustrated in, when the lid memberis pressed and heated at the annular joining portionof the containerby a publicly known method using a heat-sealing head and the like, the surface seal layerof the containerand the heat seal layerof the lid memberare melted and joined at the annular joining portion. During the heat sealing, the heat seal layerof the lid memberand the surface seal layerof the containerare melted, and protruded from an outer peripheral endof the annular joining portion (heat sealing portion)to form a lid member side resin accumulationand a container side resin accumulation. In general, during the heat sealing, heating is performed from the lid member side, and therefore the heat seal layerof the lid membermelts more than the surface seal layerof the container. As a result, the lid member side resin accumulationis larger than the container side resin accumulation, and the lid member side resin accumulationand the container side resin accumulationare integrated with each other such that the lid member side resin accumulationcovers the upper portion of the container side resin accumulation, with the lower portion of the container side resin accumulationbeing continuous from a thin heat seal layer of the side wall portion.

In this manner, when the lid memberis pulled up for opening, as illustrated in, the lid membercan be pulled up while reinforcing the lid memberbecause the lid member side resin accumulationwith a large volume is present at the point of action of an opening force P, and moreover the container side resin accumulationalso easily moves up together with the lid member side resin accumulationbecause the lid member side resin accumulationand the container side resin accumulationare integrated with each other. In this manner, the thin surface seal layerlocated at the lower portion of the container side resin accumulation, or the surface seal layerof the outer peripheral end of the joining portion thinned by heat sealing that is located on the inner side of the container side resin accumulationis easily fractured (cohesive failure). Since the surface seal layeror the surface seal layeris located near the interface with the base material layer, the interlayer peeling of the surface seal layerand the base material layercan easily proceed, thereby making it possible to easily perform an initial opening operation with a small opening force.

In addition, opening can be easily achieved as long as the lid member side resin accumulationand the container side resin accumulationprotruding from the outer peripheral endof the annular joining portion (heat sealing portion)are integrated with each other, and the lower portion of the container side resin accumulationis continuous from the thin surface seal layer of the side wall portion. However, as illustrated in, it is preferable to provide a protruding portionwhose shape of the annular joining portion as viewed from the container top surface is a shape in which the outer step portion protrudes outward in the container radial direction (so-called beak-like shape), because the stress exerted during the opening is further concentrated, and the fracture of the surface seal layerof the inner step portiondescribed later easily occurs. Alternatively, the protruding shape of the annular joining portion may be a U-shape, an L-shape, or a wave-like shape formed of a series of these shapes, for example.

In addition, in the specific example illustrated in the drawing, as described above, the inner step portionis formed inside the annular joining portionwith the inclined portiontherebetween. The surface seal layerof the inner step portionis thinner than the surface seal layerof the annular joining portion, or more preferably not formed. In the case where a groove (notch)is formed in the outer peripheral side edge portion (the lower end of the inclined portion) of the inner step portion, the surface seal layeris not formed inside the groove, or it is formed as thin as possible.

Note that, preferably, a lid member side resin accumulation′ and a container side resin accumulation′ are not formed at an inner peripheral endof the annular joining portion. Specifically, the reason for this is that if there is an integration of such resin accumulations when the internal pressure of the container increases, they are pulled up along with the lift of the lid member, and the surface seal layerunder the resin accumulation at the inner peripheral endis fractured, thus resulting in a risk of opening from the inside. As such, it is preferable that at the outer peripheral end, the container side resin accumulationand the lid member side resin accumulationare integrated, and whereas at the inner peripheral end, the resin accumulation is not formed or only the lid member side resin accumulationis present.

A simplest method of integrally forming the container side resin accumulationand the lid member side resin accumulationat the outer peripheral endis, for example, forming the annular joining portion of the container prior to heat sealing that has a high height on the outer circumference side and a low height on the inner peripheral side. In this manner, when the lid memberis heat-sealed with a flat seal head, the highest outer circumference side is preferentially melted, and the container side resin accumulationand the lid member side resin accumulationare integrally formed at the outer peripheral end, while only the lid member side resin accumulationis formed at the inner peripheral end. In addition, in the case where the annular joining portion prior to heat sealing has a flat shape with the same height on the outer circumference side and the inner peripheral side, the same effect can be achieved by using a seal head with a tapered shape. Further, even when a flat seal head is used in the case where the annular joining portion prior to heat sealing has a flat shape with the same height on the outer circumference side and the inner peripheral side, the same effect can be achieved by adopting a cantilevered structure for the flange support of the container, thereby making it difficult for pressure to be applied to the inner peripheral side.

are diagrams illustrating another aspect of the easy-open packaging body of the disclosure.is a partially enlarged cross-sectional view illustrating an enlarged view of the flange portion of an example of the container to be used,is a partially enlarged cross-sectional view illustrating a state where the lid member is set to the container flange portion illustrated infor heat sealing, andis a partially enlarged cross-sectional view illustrating a state where heat sealing has been performed from the set state illustrated in.

Also in this aspect, in general, the container includes the bottom portion (not illustrated), the barrel portion, the flange portionextending outward from the upper end of the barrel portionin the container radial direction, and the annular skirt portionextending downward from the outer peripheral edge of the flange portion. In addition, also in this aspect, the containeris integrally molded from a layered body composed of the base material layerand the surface seal layersuch that the surface seal layeris the top surface located to face the lid member (not illustrated) at the flange portion.

As is clear from, in this aspect, the flange portionforms an outer protruding portionprotruding upward on the outer circumference side, and includes an outer inclined surfacewith the outer diameter that increases toward the lower side at the boundary portion of the outer peripheral end of the outer protruding portionand the upper portion of the annular skirt portion. In addition, also on the inner peripheral side relative to the center portion, an inner protruding portionprotruding upward is formed from the center portion with an inner inclined surfacetherebetween.

As is clear from, the surface seal layerformed on the surface of the flange portionhas substantially the same thickness as the thickness of the surface seal layerof the layered body used in the range of the outer protruding portionof the container to the joining position (an installation position of a heat-sealing head)at the center portion, but its thickness decreases as it extends inward in the range of a distance Lfrom the inner peripheral endof the joining positionto the lower end of the inner inclined surfaceof the inner protruding portion. In addition, at the boundary portion between the outer peripheral end of the outer protruding portionand the upper portion of the annular skirt portion, the surface seal layerwith a very small thickness is formed (or the surface seal layer is not formed) also at the outer inclined surface. Further, also at the inner inclined surface, the surface seal layerwith a very small thickness is formed (or the surface seal layer is not formed).

As illustrated in, when the lid memberis pressed and heated at the joining position (heat sealing portion)of the containerby a publicly known method using a heat-sealing head and the like, the surface seal layerof the containerand the heat seal layerof the lid memberare melted and joined at the joining position. Also in this aspect, during the heat sealing, the heat seal layerof the lid memberand the surface seal layerof the containerare melted and protruded from the outer protruding portionin the direction of the outer inclined surfaceto form the lid member side resin accumulationand the container side resin accumulation, and the lid member side resin accumulationand the container side resin accumulationare integrated with each other such that the lid member side resin accumulationcovers the upper portion of the container side resin accumulation, with the lower portion of the container side resin accumulationbeing continuous from a thin heat seal layer of the outer inclined surface.

In this manner, as in the case illustrated in, when the lid memberis pulled up for opening, the lid membercan be pulled up while reinforcing the lid memberbecause the lid member side resin accumulationwith a large volume is present at the point of action of the opening force, and moreover the container side resin accumulationalso easily moves up together with the lid member side resin accumulationbecause the lid member side resin accumulationand the container side resin accumulationare integrated with each other. In this manner, the thin surface seal layerof the outer inclined surfacethat is present at the lower portion of the container side resin accumulationis easily fractured (cohesive failure), and then the interlayer peeling of the base material layerand the surface seal layercan proceed, thereby making it possible to easily perform an initial opening operation with a small opening force. Further, when the peeling between the base material layerand the surface seal layerhas proceeded and the inner peripheral endof the heat sealing portionhas been reached, the surface seal layersmoothly separates from the base material layerbecause the thickness of the surface seal layergradually decreases and the surface seal layeronly has a very small thickness or no surface seal layer is present at the inner inclined surface, thus making it possible to remove the lid memberfrom the container.

In the disclosure, preferably, the step (L) of the outer step portion illustrated inis, but not limited to, within a range of 0.1 mm to 0.5 mm, more preferably within a range of 0.25 mm to 0.5 mm. When the value is within the above-mentioned ranges, the contact of the resin accumulation with the outer step portion can be effectively prevented. In addition, in the second aspect, the distance Lfrom the inner peripheral endof the joining positionto the inner inclined surfaceis preferably 0.5 mm to 5.0 mm, with which the surface heat seal layer can be finally smoothly separated from the container after the interlayer peeling of the surface seal layer and the base material layer.

is a diagram illustrating another aspect of the flange portion in the container used in the easy-open packaging body of the disclosure.

As is clear from, at the top surface of the flange portion, the annular joining portion, which is heat-sealed and joined to the lid member, is formed at the center portion, and the inner step portionis formed on the inner side of the annular joining portion. In addition, in the specific example illustrated in, the outer step portionis formed on the outer side of the annular joining portion.

In the specific example illustrated in, the annular joining portionis composed of a first joining portionlocated on the outer side of the container radial direction and a second joining portionlocated on the inner side of the container radial direction. The top surface of the second joining portionis located lower than the top surface of the first joining portionby a distance Lin the container axial direction, and a width (D) of the second joining portionin the container radial direction is greater than a width (D) of the first joining portionin the container radial direction. In addition, between the first joining portionand the second joining portion, a step (side wall portion) is formed by a height difference (L) between them to form a coupling portion

In addition, as described above, in the case where the container is composed of a layered body in which the base material layerand the surface seal layerare easy to peel off, a surface seal layer′ of the side wall portionbetween the first joining portionand the outer step portionand a side wall portionbetween the second joining portionand the inner step portionare formed with a smaller thickness compared to the surface seal layerin other portions. In addition, the groove (notch)is formed at the lower end of the side wall portion, and the groove (notch)is formed at the lower end of the side wall portionor the outer peripheral side of the inner step portion.

is a partially enlarged cross-sectional view illustrating a sealed state of a packaging body in which the lid memberis joined to the container illustrated in.

As illustrated in, the container is sealed when the lid memberis heat-sealed and joined to the annular joining portionof the flange portionof the container. Specifically, the lid memberand the flange portionof the containerare not joined at the inner step portionformed on the inner side of the annular joining portionand the outer step portionformed on the outer side of the annular joining portion. As is clear from, the lid memberis composed of the base material layer, and the heat seal layercomposed of a heat-sealable resin that can be heat-sealed to the surface seal layerof the container.

As illustrated in, when the lid memberis pressed and heated at the annular joining portionof the containerby a publicly known method using a heat-sealing head and the like, a large amount of the pressure from the heat-sealing head (not illustrated) is exerted on the top surface of the first joining portion, while the pressure is less exerted on the second joining portion. As a result, at the first joining portion, the surface seal layerof the containerand the heat seal layerof the lid memberare melted and joined to a greater extent than at the second joining portion, and the resin accumulationcomposed of the surface seal layeris formed at an outer peripheral endof the first joining portion. In general, during the heat sealing, heating is performed from the lid member side and as a result, a larger amount of the heat seal layerof the lid memberis melted, thus forming a resin accumulationcomposed of a lid member heat seal layer larger than the resin accumulationcomposed of the container surface seal layer.