JPH02166066A - Easily openable container - Google Patents

Abstract

PURPOSE:To obtain a hygienic easily operable container by making a peeling strength from the inner side of the container flange stronger than a peeling strength from the outer side of the container flange. CONSTITUTION:A container 4 is composed of a basic material 5, an intermediate layer 6 which has an easily cohesion fracturing property, and an innermost layer 7 which does not have the easily cohesion fracturing property. The outer peripheral side part of the flange is made of a plastic, which has an easily cohesion fracturing property, with a film interlayer strength of 0.5-2.0kg/15mm. The inner peripheral side part of the flange is made of a plastic, which does not have an easily cohesion fracturing property, with a film interlayer strength of 2.5kg/15mm or more. When a tab 9 of a lid 1, which is protruding outside from the outer edge of the container 4, is pulled up, the easily cohesion fracturing film, which is the intermediate layer 6 of the multi-layer container 4, peels while giving cohesion fracture between its own layers, to the heat sealing final point of the container flange. Opening is performed by the cutting of a film for the innermost layer 7 at the mentioned final point, at a position of 10.

Description

[Detailed description of the invention]

A1 Objective of the invention (industrial application field) The present invention is an easy-to-open container. Specifically, in a package consisting of a lid and a container, after the contents are filled, the lid is sealed with a heat seal, and then the heat seal can be easily peeled off and opened by hand to remove the contents. Containers that can be used for (Prior Art) Some conventional easy-open containers can be heat-sealed and then opened with sufficient force by human hands. For example, so-called hot-melt adhesives are a mixture of ethylene-vinyl acetate copolymer plastics, rosin, adhesion promoters such as polyterpene resins, and petroleum waxes, or plastics formulated to have easy peelability after heat sealing are used. A so-called heat seal lacquer or the like dissolved in an appropriate solvent is coated on the base material of the lid material and dried to form a film, which is used to form a film between the lid material and the container, for example, a container made of materials such as polyvinyl chloride, polyethylene, polypropylene, etc. A sealed package, an extrusion laminate using a method commonly used in the industry using a sealant resin designed to be peelable after heat sealing as a lid material base material, or a film cast using an extrusion casting machine as an adhesive. The lidding material is bonded to the lidding base material by dry lamination using a dry lamination method, and the lidding material is hermetically packaged in a container made of each material by heat sealing. The heat seal strength of these easy-to-open containers with the lid material is 5001 J/15, which is within the range that can be peeled off with the force of a human hand.
It is adjusted to about m5 to 15,000/15 dust. (Problem H that the invention seeks to solve) However, in all cases, the seal strength is uniform over the container flange width, and those with weak seal strength have weak seal strength over the entire flange width, and those with strong seal strength Similarly, the seal strength is usually strong over the entire flange width. The ideal form for an easy-to-open container is to have a seal that is as weak as possible from the outer periphery of the flange when the lid is unsealed, that is, to be easily peeled off, and a seal from the inner periphery of the flange that contains the contents. It can be said that the sealing strength from both directions of the flange is differentiated so that the sealing strength is as strong as possible from both directions, that is, sufficient protection strength is obtained. In addition, it is preferable to heat seal the entire flange portion of the container from the viewpoint of sealing strength and safety. In addition, if there is an unsealed part on the container 7 lange, for example, if there is an unsealed part on the outside of the seal, there is a risk of contamination from the outside to this part, and if there is an unsealed part inside the sealed part, there is a risk of contamination from the outside. After the package is opened, the contents often stick to the unsealed flange, giving it a very unhygienic appearance and making it inconvenient to eat. However, at present, there is no known easy-to-open container that has a large difference in peel strength from the inside of the container and peel strength from the outside of the container when the container flange is heat-sealed to the lid material. The present invention was made in accordance with this current situation, and the present invention has been made in accordance with this current situation.
, even at Z, the peel strength from the inside of the container flange is the same as that from the outside of the container flange! (By becoming stronger than the separation strength,
The purpose is to provide a hygienic and easy-to-open container that increases the protection strength of the contents, and conversely, reduces the peel strength from the opening direction, making it easier to open and having no unsealed parts on the flange. It is said that 1. Structure of the Invention (Means for Solving Problems) The means of the present invention for achieving the above-mentioned object includes a flange portion of a plastic molded container having a flange portion that can be heat-sealed around the outer periphery of the opening; By heat-sealing the lid, in a fusion-sealed sealed container, the outer peripheral side of the flange has a film interlayer strength of 0°5 to 2.
．． The structure of an easy-to-open container is made of a plastic that has a cohesive failure property of 0 kg/15r+III, and the inner peripheral side of the flange part is made of a plastic that does not have a cohesive failure property of 2.5 kg/15 nm or more with a film interlayer strength. It is in. If the details of the structure of this container are explained based on the drawings, the lid material 1 consists of a base material 2 and a sealant 3.
For flat lid 1, stretch polyester film,
Examples include stretched nylon film. If further gas barrier properties are required, aluminum foil, metallized film,
Polyvinylidene chloride, ethylene-vinyl alcohol copolymer film, etc. are composited. In the case of the molded lid 1, the base material 2 is made of a material that can be molded, that is, cold forming (drawing) with aluminum foil with a thickness of 30 μm or more, lightly stretched or unstretched polyester, polypropylene, or unstretched polycarbonate. Can be used. The sealant 3 of the lid 1 must have the ability to fuse and seal with the plastic forming the container flange, as described above. For example, if the container flange plastic is polypropylene-based, a polypropylene-based sealant that has fusion-sealing properties to the polypropylene-based plastic is also required. This also applies to polystyrene and polyester. The container 4 has a multi-layered structure, and the one shown in the figure is composed of a base material 5, an intermediate layer 6 having a cohesive failure property, and an innermost layer 7 not having a cohesive failure property. Depending on the intended use of the container 4, an intermediate layer 6 and an innermost layer 7 of polypropylene, polystyrene, or polyester type, for example, are employed, and both are fused and sealed with the same type of plastic. The base material 5 of the container 4 can be paper, metal, plastic, etc., but the base material 5 may not be necessary in some cases. If necessary, similar to the lid material 1, other gas barrier materials 1 such as polyvinylidene chloride, ethylene-vinyl alcohol copolymer film, etc. are composited together with the base material 5. Intermediate M6, which has easy cohesive failure, usually has a film interlayer strength of 0.5 to 2.0 kg/15 mm, and can be used depending on the purpose. For example, when it is necessary to obtain as much storage strength as possible after filling the contents, such as in the case of retort food, it is preferable that the interlaminar strength of the film is 1.0 kg/15 kg or more. The innermost layer 7 that does not have easy cohesive failure property is at least the middle layer 6
It is necessary that the interlayer strength of the film is stronger than 2.5.
kg/15nwn or more is required, but if the contents are retort food, it is preferably 4°Okg/15+mn or more. The middle layer 6 and the innermost layer 7 of the container 4 are formed by coextrusion, and these two layers are fused and must not separate at the glabella interface. Next, to explain the interlayer strength of the film, the plastic used for the middle layer 6 and the innermost layer 7 of the container 4 was formed into a film with a thickness of 50 μm using a coextrusion casting machine, and the 15 μm thickness of each film and the stretched nylon film were equalized. Samples were prepared by laminating them using a dry lamination method using an adhesive commonly used in the industry. After fusion-sealing the sealing surfaces of the sample with an appropriate heat sealer, the sample was fused and sealed at 15 mm and a tensile speed of 300 mm during the test.
The peeling resistance value between the Lylum layers under the conditions of 90' peeling angle and 90' peeling angle was defined as the film interlayer strength. Regarding the method of forming the container 4, thermoforming such as vacuum forming or pressure forming from a multilayer plastic sheet can be used.
If thick aluminum foil is used as the base material 5, cold drawing can be performed, or after thermoforming the coextruded sheet of the intermediate layer 6 and innermost layer 7 into an appropriate shape, the molded product can be placed in an injection mold. A method of inserting and injection molding only five layers of the base material using plastic can also be used. Next, we will discuss a structure in which the intermediate layer 6, which is in the form of a container flange, is located on the outer peripheral side of the container flange, and the innermost layer 7, which does not have easy cohesive failure, is located on the inner peripheral side of the container flange. As a method of obtaining the intermediate layer 6 formed on the flange portion of the molded container 4 molded by the various molding methods described above,
In order to make the film of the innermost layer 7 covering the top into a flange structure, it is necessary to remove only the outer peripheral side. Examples of this method include cutting the outer peripheral side of the flange using a highly accurate lathe or other device with a sharp blade, or grinding the flange using a grinder using a grinding wheel. The method is not limited. The innermost layer 7 of the container 4 has a film thickness of 30 μm or less, preferably 5 to 20 μm, and the intermediate layer 6 has a film thickness of 5 μm or more, preferably 10 to 20 μm. The ratio of the innermost layer 7 of the container flange to the middle layer 6 in the flange width direction is preferably 4:1 or more, preferably equally divided from both the inside and outside sides. The heat sealing device 8 seals the lid material 1 onto the container 4. heat seal

[↑] is preferably heat-sealed throughout the container flange, but if it is heat-sealed with the lid material 1 centering on the bonding interface between the innermost layer 7 and the middle M6 of the container flange, it will be heat-sealed throughout the container flange. As with heat sealing, sufficient performance can be obtained in terms of strength, but one of the purposes of the present invention is to heat seal the container flange over all 11 parts and to create a sanitary container with no unsealed parts. Since it is not satisfactory in terms of providing a target container, it is necessary to select it according to the purpose. (Function) As shown in FIG. 1 of the drawings, the easy-to-open container configured as described above can be used by pulling up the gripping portion 9 of the lid 1 extending outward from the outer edge of the container 4 in the peeling direction. Middle layer 6 of multilayer container 4
As shown in FIG. 2, the cohesively failure-prone film peels off until it reaches the final point of heat-sealing on the container 7 lunge while causing cohesive failure between its own eyebrows. The package is opened by cutting the package. The cutting of the heat-sealed innermost layer 7 film is thought to be due to the stress concentration effect that occurs at the heat-sealed red part when the film and the intermediate layer 6 film are fused together, but the stress concentration effect is more pronounced. In order to achieve this, the thickness of the film of the innermost layer 7 can be reduced by providing a protrusion on the flange located in this area, or by applying greater pressure to this area using a heat sealing device. Methods that make cutting easier can also be used. The stress at the cutting position 10 at the final point of heat sealing is:
When peeling is performed from the inside of the container, the peeling rate is larger than when peeling is performed from the outside as described above, and in some cases, it is twice or more. The reason for this is not clear, but due to the heat and pressure in the heat-sealed red area, the release film layer on the outside of this red area becomes thinner, and conversely, the release film layer on the inside becomes thinner, as shown in Figure 1. It is thought that the difference in tensile strength occurs due to the protrusion. In this way, the peel strength from the inside of the flange of the container 4 becomes stronger than the iIr* strength from the outside of the container flange, thereby increasing the protection strength of the contents, and conversely, the peel strength from the opening direction becomes weaker, so that The purpose of making it easier to open is achieved. The coextruded plastic of the intermediate layer 6 film and the innermost layer 7 film constituting the multilayer container 4 has a cohesively ruptureable film structured in the width direction of the container flange, which is a feature of the present invention. There is no limit to the range in which the sealant 3 of the lid material 1 satisfies the conditions that the films that do not exist are firmly adhered to each other by heat fusion and have fusion sealability with each other. Polypropylene resins, polystyrene resins, polyester resins, polyethylene resins, mixtures thereof, and combinations of other additives can be used. (Example) Examples of the easy-open container of the present invention will be described below. Example 1 A multilayer container 4 and a lid 1 constructed as shown in FIG. 1 were heat-sealed. MFR()I of the innermost layer 7 of the multilayer container 4
F5 block Fl-OW Rate230℃) =9
1 J/10 min) of polypropylene (melting point 160 °C, tensile strength 450 kg/cyi = . elongation 400%) and the middle layer 6 of the multilayer container MFR = 9 (
Multi-layer container 4 with a blend resin of polypropylene (melting point iso ℃, tensile strength 350 kg/cxl, elongation 50%) mixed with 20 wt% of inorganic filler talc (g/10 min)
A three-layer coextruded multilayer sheet 800 μm thick (MFR = 2 Co /10 min) of base layer 5 of polypropylene (melting point 165°C, tensile strength 550 kg/cJ, elongation 500%)
Innermost layer film thickness = 10 μm, middle layer 6 film thickness 20
µm, base material layer sheet thickness = 770 µm), and vacuum formed the sheet to a diameter of 50 mm. A multilayer container 4 having a depth of 30 mm and a flange width of 8 mm was molded. The film surface of the innermost layer 7 was exposed up to 4nwn from the outer peripheral edge of the flange portion of the container 4. This container 4 is made of a stretched nylon film with a thickness of 15 μm and a polypropylene film with a thickness of 60 μm, which is commonly used in the block copolymer retort pouch packaging material used in the industry.
The cover material 1, which was thickly bonded with a polyurethane adhesive, was heat-sealed during the flange process. Heat sealing conditions are temperature 190℃, pressure '5hg/a
i, sealing time is 1.0 seconds. This heat-sealed part was cut into a width of 1511W11, and 300mm was cut from both the outside and inside of the flange.
Seal strength was measured by peel rate in mm/min. The measurement result is 1.5kg/15n from the outside direction of the flange.
m, but from the inside of the flange it was 3.5 kl (
It showed 715 nym. The peeled surface of the sample from the outside of the flange was clean with no fluff or hangnails. The heat seal strength was measured using the same method for those that had been retorted at 120°C for 30 minutes after being sealed, but a slight decrease in seal strength was observed, but from the outside of each flange it was 1.2 kg/15nwm, and from the inside of the flange showed a sealing strength of 3.5 kg/15mm. This value is 2.3 kg/15 nm, which is the sealing strength standard value for retort food packaging containers stipulated by law.
It was meant to clear the issue. Example 2 Heat sealing was performed on a multilayer container 4 and a lid 1 having a structure as shown in FIG. MFR (ME) of the innermost layer 7 of the multilayer container 4
L-cho FLOW Rate200℃) =7 (
a /10 minutes) polystyrene (tensile strength 270 kg
/cd, elongation 40%) and a styrene-grafted ethylene vinyl acetate copolymer (M I = 12.5°, specific gravity 0.945, melting point 92°C) in which iowt% of styrene component was graft-polymerized to the intermediate layer 6 of the multilayer container. The above-mentioned polystyrene 20
MFR=2.3 (
9/10 minutes) polystyrene (tensile strength 330 kg/
csJ, elongation 50%) 1-800μm
Thickness (film thickness of innermost layer 7 = 20 μm, film thickness of intermediate layer 6 = 20.tzm, sheet thickness of base material layer 5 = 760 μm
m>, and the sheet was pressure-formed to a diameter of 50 mm. A multilayer container 4 having a depth of 30 mm, a width of 7 lunges, and 8 dimensions was molded. The film of the innermost layer 7 was removed in a ring shape from the outer peripheral edge of the flange portion of the container 4 to 41IIfflI using a cutting device such as a lathe to expose the surface of the film of the intermediate layer 6. This container 4 was covered with a lid 1 by heat sealing, which was made by dry laminating a 12 μm thick stretched polyester film and a 40 μm thick styrene film, which is commonly used in the industry as a lid sealant for polystyrene tofu containers. Heat sealing conditions were: temperature 160°C, pressure 3hg/d,
The sealing time was 1.0 seconds. This seal portion was cut to a width of 15 m, and the seal strength was measured from both the outer and inner sides of the flange at a peeling rate of 300 nym/min. The measurement results were 0°8 kg/15 mm from the flange outer circumferential direction, but 1.5 kg/1 s from the flange inner direction. The peeled surface of the sample from the outside of the flange was clean with no fuzz, hangnails, etc. Comparative example 1゜Example 1. The same test as in Example 1 was carried out by changing the middle layer 6 of the multilayer container 4 to a mixture of ethylene-vinyl acetate copolymer plastic with M1=5, 10 wt% vinyl acetate, and 10 wt% vinyl terpene adhesive agent. went. As a result, the film of the intermediate layer 6 and the sealant 3 of the lid material 1 showed a peel strength of 500 g / 15 mm, but since the film of the innermost layer 7 was not fused and sealed, the final red part of the heat seal was Since separation from the film of the innermost layer 7 occurred, stress concentration for rupture could not occur in this part, and a uniform rupture force was not generated, resulting in a loss of commercial value. Comparative example 2゜Example 1. The outer peripheral side of the container flange of the innermost layer 7 of the multilayer container 4 was heat-sealed with the lid material 1 without removing the film surface of the intermediate layer 6, and the sealed portion was cut to 15 mm to form a flange. The seal strength was measured from the outside direction and the inside direction at a peeling rate of 300 ran/min, respectively. The measurement result is 3.0 kg7 from the outside direction of the flange.
15mm, 3.5kg/15mm from the inside of the flange
It showed a seal strength of , so it was not easy to open. Effects of the Invention The easy-to-open container of the present invention exhibits good ease of opening, with the container flange being easily opened from the opening direction, that is, from the outside; The seal from the inside is strong and difficult to open, providing excellent seal protection. Since the lid sealant and the container flange are sealed with a fusion seal, it has excellent contaminant sealing properties. Since the container flange is heat-sealed across the gold mine and there is no unsealed part, the container flange can become contaminated by foreign matter entering from the outside, and the contents can get trapped inside after opening. An easy-to-open container that does not cause hygiene issues or difficulty in handling can be obtained, making it a dessert. It can be used as packaging containers for a wide range of foods such as prepared foods and retort foods (cooked foods, soups, etc.). It has the following unique effects.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a closed state of an easy-to-open container according to the present invention. FIG. 2 is an enlarged sectional view of a portion of the same as the above, showing an unsealed state. In the figure, 1M material, 2 is the base material, 3 is the sealant, 4 is the multilayer container, 5 is the base material, 6 is the intermediate layer, 7 is the innermost layer, 8 is the heat sealing device, 1o is the grip part of the lid material 1 It is.

Claims (2)

[Claims] (1) By heat-sealing the flange of a plastic molded container equipped with a flange that can be heat-sealed on the outer periphery of the opening and the lid material, the flange of the flange of the fusion-sealed sealed container can be The outer peripheral side part is made of plastic that has a cohesive failure property with a film interlayer strength of 0.5 to 2.0 kg/15 mm, and the inner peripheral side part of the flange part has a cohesive failure property of a film interlayer strength of 2.5 kg/15 mm or more. An easy-to-open container characterized by being made of non-toxic plastic. (2) Easy-opening, characterized in that the plastic having cohesive failure property according to claim (1) is fused to a plastic having no cohesive failure property except for the outer peripheral side of the flange. container.