JPH0329768A - Easily unsealable container package - Google Patents

Abstract

PURPOSE:To bring the title package to a predetermined sealing strength and to make the package easily unsealable by providing a container, which is obtained through continuously thinning the innermost layer plastic film layer of the inside annular part of a flange, with a cover material. CONSTITUTION:The tile package is constituted in such manner that easily cohesive failing plastic 4-2 and plastic film 4-3 having no easily cohesive failing properties adhere in a fused state to a container base material 4-1. When a container 1 is made from these multi-layer sheets and films, a projected stripe 3-2, which is recessed on the base material 4-1 and projected on the innermost layer 4-3 side, is provided in the inside annular part 3-1 in a flange 11. Then, the innermost layer plastic film layer 4-3 is thinned, when the tip of the projected stripe 3-2 is hot-pressed by a heat embossing board. After that, the container 1 is filled with contents and covered with a cover material 2 and a heat-seal ring 7. When the end 8 of the cover material is pulled up at the time of unsealing, an intermediate layer 4-2 cohesiveness fails in the position indicated by a two-dot chain line while cutting occurs in the thinnest part (h) of the innermost layer plastic film 4-3 to perform unsealing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an easily openable container packaging body used in the industry of sealing and packaging foods. Specifically, in a package consisting of a lid and a container, after the container is filled with contents, the container and the lid are sealed by heat sealing, and then the contents can be easily removed by hand. A container package that can be opened by peeling off the heat-sealed part. (Prior Art) Some conventional easy-open packages are sealed by heat sealing and can be opened with sufficient force by the human hand. For example, a so-called hot melt adhesive is a mixture of ethylene-vinyl acetate copolymer plastic and rosin, an adhesion agent such as polyterpene resin, petroleum wax, etc., or a mixture that is appropriately formulated to have easy peelability after heat sealing. A so-called heat seal lacquer or the like, which is prepared by dissolving the resulting composition in a suitable solvent, is applied to the base material of the lid material and dried to form a film, which can be used for lid materials and containers, such as polyvinyl chloride, polyethylene, polyester. , polypropylene, polycarbonate, etc., extrusion lamination using a method commonly used in the industry, or easily peelable film casting using an extrusion casting machine using a sealant resin designed to be peelable after heat sealing. These containers and packages are made by heat-sealing the lid material onto the lid material base material using a dry lamination method using an adhesive, and then heat-sealing the lid material to a container made of various materials. Furthermore, there are proposals for technologies that increase the heat seal strength to achieve a seal strength that exceeds the legal standard value of 2.3 kg/15 av+ for retort food containers, and also provide easy-opening properties. For example, in Japanese Patent Application Laid-Open No. 62-251363, a cut is provided in the innermost plastic film of an easily peelable sealant, and the outer layer is combined with an adjacent plastic layer adjusted to be peelable between the eyebrows. However, in the easy-open container produced by such a method, the innermost layer of the easy-open sealant and the adjacent layer plastic film are
Since it has a so-called interlayer peeling structure that peels off at the interface, if the innermost layer plastic film is not sufficiently incised, the intended purpose will not be achieved, so it is likely that cutting debris will be generated during the incision. It is difficult to completely remove this substance, and there is a risk that the substance may contaminate the food contents. Furthermore, due to the uneven thickness of the multilayer plastic sheet, it is impossible to make cuts of uniform depth around the flange edge, resulting in disadvantages such as variations in peeling force. (Problem to be Solved by the Invention) The heat seal strength between the lid material and the container of these easy-to-open packages is 0.5, which is within the range that can be peeled off appropriately with the force of human hands.
kg/15 ■Organic or 1.5 kg/l! It has been adjusted to about +++m. Furthermore, the heat sealing strength has been increased, for example, the legal standard value for retort food containers is 2.3 kg/
Many technologies have been proposed in terms of composition, structure, etc. that extend the range to 15 mm or more and are easy to open, but all of them have a narrow range of heat sealing conditions and lack stability, or are structurally dependent on the material. Due to technical restrictions, it is not possible to use polypropylene or heat-resistant polyester, and at most only high-density polyethylene can be used.
It has drawbacks in terms of appearance and cost, such as the inability to retort sterilize at temperatures above 0°C, and the need to make a notch in the flange, making the flange wider than necessary. The ideal form of an easy-to-open package is that when peeling the heat-sealed lid from the container, the sealing strength is as weak as possible from the outside of the flange, that is, from the opening direction, so that it can be opened easily; In other words, the seal must be as strong as possible from the direction of the contents, and the structure must be sufficient to protect the contents. To achieve this, it is necessary that there be a difference in seal strength from both the inner and outer circumferences of the flange. Some of the conventional techniques mentioned above are based on this viewpoint, but they have drawbacks as mentioned above.

The present invention overcomes these drawbacks of the prior art, enables retort sterilization at temperatures above 120°C, and achieves sealing strength exceeding the legal standard value of 2.3 kg/15 mm for retort food containers, making it suitable for use even by the elderly and children. The object of the present invention is to provide an ideal easy-to-open container package that can be opened satisfactorily.

Means for Solving Problem C) The means of the present invention for achieving the above-mentioned object is as follows: In a container provided with a flange portion on the outer periphery of the opening for heat-sealing and sealing with a lid material, the flange portion Adjacent to the innermost plastic film having an interlayer strength of 2.5 kg/15III1 or more on the upper surface of the film, the film is adhered in a fused state and has an interlayer strength of 0.5 to 2.0 kg/1.
A lid material or container that can be heat-sealed to a container in which the innermost plastic film layer on the inner annular portion of the upper surface of the flange is continuously thinned by enclosing an easily peelable plastic sealant with a 5 mm cohesive failure property. This can be achieved by using a container with a structure in which the flange part on the outer peripheral side is heat-sealed by at least 2 mm from the thinned part. In addition, to explain the interlayer strength of the film, the plastic used for each layer was formed into a film with a thickness of 50 μm using an extrusion casting machine, and the thickness of each film and the stretched nylon film was 15 μm, as is commonly used in the industry. A sample is created by laminating the materials using a dry lamination method using an adhesive. After performing a fusion seal between the sealing surfaces of the sample using a hot plate sealer, a test width of 15
mm. Tensile speed 300m*/win, peeling angle 9
The peel resistance value between the film layers under the condition of 0° was defined as the film interlayer strength. Next, to explain the present invention with reference to the attached drawings, FIG. 1 is a cross-sectional view of a multilayer sheet for making a container 1 of the present invention, in which a container base material 4-1 is coated with a cohesively ruptureable plastic 4-2 and an easily cohesive failure plastic 4-2. It consists of a plastic film 4-3 that does not have cohesive failure properties and is adhered in a fused state. In addition,
Another barrier film, for example, a vinylidene chloride film, an ethylene-vinyl alcohol copolymer film, or a metal foil such as aluminum foil may be composited between the base layer 4-1 and the intermediate layer 4-2. ．． When making the container l according to the present invention from these multilayer sheets and films, first, as shown in FIG. Add a protrusion 3-2 that is convex on the side. Although the size of the protruding portion 3-2 of the innermost layer 4-3 is appropriate,
Generally, a width of about 1 m+a and a height of about 1 mm is appropriate.

The forming method can be thermoforming such as vacuum forming or pressure forming. The molding position of the protruding portion 3-2 is preferably a position approximately one inch from the opening periphery of the container l.

Next, as shown in FIG. 3, the protrusion 3-2 on the surface of the innermost plastic layer 4-3 of the inner annular portion 3-1 of the flange 1) is heated by heating the tip of the protrusion 3-2 with a hot press plate. By pressing, the innermost plastic film layer 4-3 is made thinner. Innermost plastic layer 4- of said part 3-2
Although the appropriate minimum thickness of No. 3 varies depending on the plastic material, for example, in the case of polypropylene, it is 15 μm or less, preferably 5 to 10 μm thick. 4-A and 4-B are plan views of round and square containers 1 of the present invention, in which a flange 1l is provided on the outer periphery of the opening, and a flange 1l is provided on the inner annular portion 3-1. The thinned part 3-2 of the uppermost (inner) plastic layer obtained by hot-pressing the uppermost protruding strip 3-2 and the unthinned part 3-1 are shown. The method for thinning the container 1 or the lid material 2 at a predetermined position is as follows. In the container forming process shown in FIG. 5, the multilayer plastic sheet of the present invention (a) is sufficiently plasticized on both sides by a thermoforming device such as a vacuum forming machine or a pressure forming machine, and by a sheet softening device (b) using infrared rays or the like. In this state, the inner annular part 3 of the flange 1) is inserted into the inner annular part 3 of the flange 1) as shown in FIG.
-1 is formed on the container 1 having a continuous protrusion 3-2. At the same time, the tip of the protruding part 3-2 is pressed by the embossing plate E to about 1/2 of the height of the formed protruding part 3-2. If the shape of the container or the positional relationship with the plug 2 is inconvenient, the container can be fitted into a special mold for embossing on stage B, and then the flange 11 can be plasticized and stamped again using a hot embossing board. Apply heat and pressure to an appropriate degree using E. Thereafter, it is punched into a container shape using a punching device to obtain a container chip of the present invention in which the flange 1) is thinned at a predetermined position.

Next, in the cup sealer of FIG. 6, as shown in FIG. 2, the inner annular portion 3-1 of the flange 1l is
After a container container having a continuous protruding part 3-2 is received by the container receiver, the protruding part 3-2 of the flange 1) is suitably removed by a hot press plate in the C stage before filling the contents. After applying heat and pressure to a certain degree to reduce the thickness at a predetermined position, the container is filled with the contents using a filling machine to obtain a sealed container package in which the lid material has been punched out.

FIG. 7 shows a structural container 1 of the present invention covered with a lid 2 and a heat seal ring 7. As shown in the figure, from the thin-walled portion 3-2 to the flange l1
1a+m or more, preferably 2~m on the outside or corresponding outside part
It is best to heat seal the lid at the 4IIIIII+ position.

(Function) The present invention configured as described above has the following effects. Fig. 8 shows an enlarged view of the part of the innermost plastic layer 4-3 of the innermost plastic layer 4-3 of the inner annular portion of the flange 1) which has been heat-embossed. -3 is crushed, and the thickness of the adjacent layer of easily cohesive failure plastic layer 4-2 with the protrusion 3-2 becomes smaller, that is,
The layer 4-3 is thinned to a thickness h in the figure. FIG. 9-1 shows an enlarged view of the structural container of the present invention with the lid closed and heat sealed in the predetermined position b as described above.

When opening, by pulling up the end 8 of the lid,
At the position indicated by the two-dot chain line in FIG.
The plastic film progresses to the thinned protrusion forming portion 3-2 while undergoing cohesive failure, and the innermost plastic film 4- shown in FIG.
A cut occurs at the thinnest part h of No. 3 and the seal is opened.

Figure 9-2 shows an enlarged view of the unsealed part. The progress of cutting from the intermediate layer 4-2 to the thinnest portion h of the innermost layer 4-3 is smoothly performed because both layers are bonded together in a fused state.

If separation occurs between the eyebrows, cutting will not be done smoothly. In addition, in the container structure of the present invention, when the sealed portion is peeled from the inside by heat-sealing the lid at such a position, the point of peeling occurs at position 10 in Figure 9-1. Since it cannot be removed without cutting, the protection of the contents is greatly increased.

In the structure of the present invention, the peel strength inside the container can be four times or more than the peel strength from the outside. For example, in a polypropylene container, the peel strength from the outside is 1
kg/15mm, but a peeling force of 4 kg/15III1 can be obtained from the inside of the container, which means that the sealing strength for retort food stipulated by law is 2.3 kg.
/ 15m+a can be cleared sufficiently.

(Example) An example of an easy-to-open container package according to the present invention will be described below based on the drawings.

In FIG. 1, first, the innermost layer of the container 4-3, which does not have easy cohesive failure, has an MFR value of 9 g/10n+in and a melting point of 160°C. Tensile strength 450kg/cm", elongation 4
4-2 C MFR value 20g/10n+
in, melting point 150℃, tensile strength 300kg/cm”
, polypropylene with 100% elongation, MI value 7, specific gravity 0.
92, tensile strength 300kg/c+s”, elongation 50
0% polyethylene lOwt% and inorganic filler talc
(Using a blended resin mixed with Owt%) and base material layer 4i
MFR value 2 g/10a+in, melting point 165℃,
Using polypropylene with a tensile strength of 550 kg/cys" and an elongation of 500%), a multilayer sheet with a thickness of 800 μm (innermost layer film thickness of 80 μm, middle layer thickness of 4 μm) is produced by three-layer coextrusion.
0 μm diameter, 680 μm thick base material sheet) and molded the sheet into 5hm diameter, 30 mm depth, flange 1 using a vacuum forming machine.
) 41) Projection 3 with a width of 1 mm and a height of 1 mm in 10 mm
-2 was molded using a mold C that was continuously provided to the inner annular portion 3-1 of the flange 1) of the innermost layer 4-3. Next, the container is placed in the C stage of the cup sealer shown in FIG. 6, and the protruding portion 3-2 is removed by a hot press plate set at 180°C (the contact surface is mold release processed by baking Teflon). As a result of hot pressing to a height of .5 mm, the thinnest portion of the innermost plastic film 4-3 of the portion 3-2 was formed to have a thickness of 5 μm. After filling the structural container of the present invention with beef stew, a 15 μm thick stretched nylon film was used as the lid material, and a 60 μm thick polypropylene film, which is commonly used in block copolymer retort pouch packaging materials in the industry, was used as the lid material.
After sealing the container by heat-sealing the lid material laminated with a polyurethane adhesive by a width of 5a+m from the outside of the flange of the container, the container was retorted at 125°C for 30 minutes. When the package was opened after cooling, it peeled off smoothly and could be opened, as shown in Figure 9-2. No fluff or hangnails were observed on the peeled surface. Incidentally, cut this heat-sealed part to a width of 15a+m and cut it 300m from both the outside and inside of the flange.
Seal strength was measured by peeling speed of m/win. The measurement result is 1.2kg 715m from the outside of the flange.
m, but from the inside of the flange it was 4.5 kg/
It showed 15o+m.

This value is for retort food packaging containers stipulated by law.
It passed the standard sealing strength of 2.3kg/15a+m. (Comparative example) (A test similar to that of the example was conducted in the case where the intermediate layer 4-2 of the multilayer container of the al example was omitted from the inorganic filler talc which has the effect of imparting cohesive failure property. Because it does not have cohesive failure properties, no fracture occurred at the point where it should have broken, and although it barely broke at the opening, it could not be broken uniformly. (b) The intermediate layer 4-2 was replaced with the innermost layer 4- 3 and a formulation that can be interfacially peeled, for example, high-density polyethylene (specific gravity 0.95)
50wt% and ethylene-propylene rubber (specific gravity 0.
88) A test similar to the above example was conducted using a 50 wt% blend, but since the intermediate layer was not adhered to the innermost layer in a fused state, the comparative example (a) ), the point where it was supposed to break did not break, resulting in a very dirty peeling surface and no commercial value. (c) II from the thin-walled molded part of the multilayer container flange of the example
For the lid material heat-sealed to the II1 position,
The seal strengths from the inner and outer circumferential directions of the flanges were measured, and both showed a seal strength of 1.2 kg/15 mm, so the protection strength of the contents was uncertain.

When the product was retorted at 125°C for 30 minutes, some parts of the seal part peeled off, causing seal leakage. (Effects of the Invention) The easy-to-open container package of the present invention exhibits good easy-to-open properties because the container flange is easily opened from the opening direction, that is, from the outside. That is, in a container that has excellent sealing protection strength because the seal strength is strong from the inside and it is difficult to open, there is no generation of cut debris due to the structure of conventional products, which is one of the objects of the present invention. A cutting and opening action can be obtained by forming a uniform thin wall portion that is not affected by uneven thickness of the flange portion.

Additionally, since the lid sealant and the container flange are sealed with a fusion seal, it has excellent contaminant sealing properties. The peeling mechanism upon opening is achieved by interlayer peeling of the easily cohesive failure film, allowing a wide range of sealing conditions and stable sealing strength. Furthermore, if it is applied to polypropylene or polyester-based containers with high heat resistance, the legal standard values for retort food can be achieved.

It can also be widely applied to other polystyrene, polyethylene containers, etc.

It has unique effects such as

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view showing a state in which a multilayer sheet is formed. Second
The figure is a cross-sectional view of the container flange after the protrusion is bulged. Figure 3 is an enlarged cross-sectional view showing the state in which the protrusion is hot-pressed. 4-A and 4-B are plan views of containers related to the present invention. Figures 5 and 6 are explanatory diagrams showing the molded state of the container. Figure 7 is a longitudinal sectional front view showing the molded state of the package. Figure 8 is an enlarged view of the protrusion after it has been hot-pressed. FIG. 9-1 is an enlarged sectional view showing the fused state of the seal portion. FIG. 9-2 is an enlarged front view showing the peeled state of the same as above. In the figure, 1 is a container. 2 is the lid material. 3-1 is 1l flange
Annular parts on the inner and outer peripheries. 3-2 is the protrusion. 4-3 is the innermost plastic layer that does not have cohesive failure properties. 4-2 is a plastic intermediate layer with easy cohesive failure property. 4-1 is a base material layer. There are two pressing means. The heat pressure means is E. l No. +8 9-4 2 No. 5e

Claims (4)

[Claims] (1) A film adhering in a fused state adjacent to the innermost plastic film having an interlayer strength of 2.5 kg/15 mm or more, an interlayer strength of 0.5 to 2.0 kg.
/15 mm of plastic having a cohesive failure property as an easily releasable sealant.A container having a lid and a flange for sealing by heat sealing on the outer periphery of an opening manufactured from a multilayer plastic sheet using an easily releasable sealant. An easily openable container package characterized in that a lid material is applied to a container in which the innermost plastic film layer of the inner annular portion is continuously thinned. (2) The container according to claim (1), wherein a ridge is formed by pressing from below with a pressing means on the upper surface of the flange of the container, and the ridge is thinned by flattening the ridge with a heat-pressing means. Easy-open container packaging. (3) A claim characterized in that the position of heat-sealing to the container flange is such that the innermost plastic film of the easily peelable sealant is heat-sealed 2 mm or more outward from the continuously thinned inner annular portion. The easy-open container package according to item (1) or (2). (4) The peeling structure of the sealant starts from interlayer peeling between the easily cohesively fractured plastic films in the intermediate layer at the outer cross-sectional end of the container flange, and cutting in the cross-sectional direction of the innermost plastic film in the thinned part of the structure of the present invention Claim (1) or (2) or (
3) The easy-to-open container package described above.