JP2740014B2 - Manufacturing method of sealed container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to the production of a sealed container which can be easily opened in a container comprising a plastic cup body having a flange portion and a lid member. About the method.

[Conventional technology]

2. Description of the Related Art As a container for packaging various foods, a plastic sealed container having an easy-open structure that can be easily opened with a lid is widely used.

The most common easy-open type structure that has been practically used in the past is to change the composition of the resin that constitutes the sealing layer of the lid material so that the sealing strength with the container flange can be adjusted within a suitable range (usually 500 to 1500 g / 15mm), and the seal interface is peeled off and opened (interface peeling type).

However, in this interfacial peeling type, since the sealing strength to be applied is easily affected by the conditions at the time of sealing, environmental temperature, adhesion of contents, and the like, it is difficult to control the target range, and large fluctuations often occur. There are difficulties. This variation causes seal leakage when biased toward the weak side, and conversely, when biased toward the strong side, impairs peelability and impairs easy-openability, but the former seal leakage is a fatal defect as a container. Therefore, there is usually a need for a means for setting the heat pressure condition of the seal at a higher value even at the expense of peelability.

In order to improve such problems, for example, Japanese Patent Publication No. 59-3
As described in Japanese Patent No. 7597, there is known a method of delamination between a sealing layer on a container side and a layer adjacent to the sealing layer to open (delamination type). However, if this structure is to be adopted by a normal sealing method, there is a problem that the sealing layer portion does not break smoothly, and it is difficult to take out the contents.

In this case, in order to facilitate separation between the peeling layer and the adjacent layer, a structure is provided in which a notch is provided in the flange portion (Japanese Patent Laid-Open No. 62-2).
No. 51363, No. 63-78, No. 63-25037),
Many improvement proposals have been made, such as a structure in which a notch for starting peeling and a notch for stopping peeling are provided in the flange portion (Japanese Patent Application Laid-Open No. 63-96060), but there is a risk of impairing the pressure resistance in these structures. is there. In addition, if the sealing position is not properly controlled, the seal portion is difficult to be cut, and there are cases where the lid and the container body do not separate, so that the opening may not be performed smoothly.

[Problems to be solved by the invention]

The inventor has conducted intensive studies on a seal structure that achieves both pressure-tightness and easy-peeling performance, which are considered to be contradictory performances in the prior art, and as a result, after installing a specific punched portion on the container flange portion, the injection resin is formed on the outer peripheral surface. The present invention has been developed after confirming the fact that, when the layer is formed, the easy opening property is imparted without impairing the sealing property due to the intervening action of the injection resin filled in the punched portion.

Accordingly, an object of the present invention is to provide a method for manufacturing a sealed container that can be easily opened via smooth delamination while maintaining sufficient pressure tightness.

[Means for solving the problem]

In order to achieve the above object, a method for producing a sealed container according to the present invention comprises a lid having at least two container flange portions having a laminate strength of 300 to 2000 g / 15 mm between a sealing layer and an adjacent layer and a sealing layer surface. In manufacturing a sealed container by heat-sealing the material and the seal strength to a state where the seal strength is equal to or higher than the laminate strength, a punching slit having a non-punched portion is intermittently provided in advance along the inner edge of the container flange portion. After that, a resin that is bonded to the outermost layer of the container on the outer peripheral portion of the container and is not bonded or hardly bonded to the sealing layer surface of the lid material by injection molding to form a layer and fill the punching slit portion, and then fill the punching slit portion with the peripheral side of the punching slit. It is characterized in that the sealing layer surface of the lid member is heat-sealed.

 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a container body provided with a flange portion 1 formed into a predetermined shape by, for example, vacuum forming, and is composed of a multilayer sheet of at least two layers including a sealing layer 2 and an adjacent layer 3 opposed thereto. The configuration of the multilayer sheet may be, for example, a two-layer sheet in which a polyethylene resin is disposed in the seal layer 2 and a polypropylene resin is disposed in the adjacent layer 3. Further, a saponified ethylene-vinyl acetate copolymer or It may be a multilayer sheet in which a barrier layer of polyvinylidene chloride resin, an adhesive layer and an outermost layer of polypropylene are arranged.

In this case, it is important that the lamination strength between the sealing layer 2 and the adjacent layer 3 is 300 to 2000 g / 15 mm, and that the sealing strength is sufficiently secured at a lamination strength of less than 300 g / 15 mm. On the other hand, 2000g /
If it exceeds 15 mm, the smooth peeling property at the time of opening will be impaired.

The non-punched portion 4 is intermittently formed on the flange portion 1 of the container having the above-described structure in advance along the inner edge as shown in the plan view of FIG.
And a punching slit 5 having the following. A-
FIG. 3 is a sectional view taken along the line A '.
As a formation pattern of the punching slits 5, it is desirable that the non-punched portions 4 are arranged at equal intervals, the length is as short as possible, and the number of installation locations is reduced.

The punching slit 5 is usually formed automatically using a lifting / lowering cutting device equipped with a punching blade having a cut portion for providing a non-punched portion at the cutting edge. It is efficient to process continuously as a post-process of stamping.

The container subjected to the above processing is set in a mold of an injection molding machine, and a resin is injection-molded on the outer peripheral surface thereof. As the resin material to be injected, a resin material which has adhesiveness to the outermost layer of the container, which is to be directly formed, but does not adhere to or hardly adheres to the sealing layer surface of the lid material is selected and used. Therefore, it is preferable to use the same resin as the outermost layer of the container but different from the sealing layer, and in many cases, a polypropylene-based resin is suitably used.

By this injection molding, an injection resin layer 6 is formed on the outermost layer surface of the container as shown in FIG. 4, and the resin is also filled in the punching slit 5 of the flange portion 1.

Next, the peripheral side of the punching slit 5 of the container flange portion and the sealing layer surface 8 of the lid 7 are overlapped and heat-sealed to form the sealed container of the present invention.

[Action]

In the hermetically sealed container manufactured by the above-described process of the present invention, the container flange portion 1 and the lid member 7 are completely sealed via the mutual sealing layer, and the outer peripheral surface of the container is composited with the injection resin layer 6. Formed and punched slit 5
Is filled with injection resin, so it is structurally strong,
Extremely high pressure resistance against external and internal pressure.

In order to open the container, when the tongue of the lid 7 is gripped and pulled upward, delamination starts smoothly between the sealing layer 2 and the adjacent layer 3 of the container flange 1 as shown in FIG. You. When the exfoliation reaches the position of the punching slit 5, the injected resin filled here does not adhere to the sealing layer surface 8 of the lid material, and the light peeling proceeds as it is. At the position of the non-punched portion 4, the seal portion is cut,
The cutting distance of this part is extremely short, and the force X in the peel direction is
Also works along the arrows in FIG. 7, so that there is no large resistance and the appearance of the cut surface is good.

Easy opening is developed through such delamination and cutting action.

〔Example〕

Sealing layer 2 made of high density polyethylene (HDPE) with a density of 0.955 and a melt index (MI) of 5 g / 10 min, and polypropylene (PP) with a melt index (MI) of 0.5 g / min
Co-extruded two-layer sheet of adjacent layer 3 (also serving as the outermost layer) made of vacuum-formed, 70 mm inner diameter, 82 mm flange outer diameter, 30 height
mm container body was formed (FIG. 1). The flange thickness of this container body is 400 μm, the thickness of the sealing layer is 20 μm, and the lamination strength of the sealing layer 2 and the adjacent layer 3 is 1200 g / 15.
mm.

A punching slit 5 having a width of 0.5 mm and a non-punching portion 4 having a length of 2 mm installed at five equally spaced locations along the inner edge at a position 1 mm from the inner diameter end of the flange portion 1 of the container was provided by a punching blade ( (FIG. 2, FIG. 3).

Then, the container is set in a mold of an injection molding machine, and the same polypropylene as the adjacent layer 3 is injection-molded to form an injection resin layer 6 having a thickness of 0.8 mm on the outer peripheral surface of the container. Filled (FIG. 4).

On the container flange after injection molding, the sealing layer surface 8 is made of high-density polyethylene biaxially stretched 6-6 Ny (ony) 25μ / HDPE 60
The cover member 7 made of μ was overlaid, and the periphery of the punched slit 5 in the flange portion was heat-sealed at a temperature of 190 ° C. and a pressure of 10 kg / cm ² (FIG. 5). The seal strength between the seal layers is
3000 g / 15 mm.

When the lid was opened for the obtained sealed container, it could be opened smoothly to the end with a very light peel feeling,
The state of the opened surface was also fluffy, and phenomena such as uneven deformation were not observed.

A sticky rubber plate (thickness: 1.5 mm) was attached to the center of the lid, and the pressure at the time of puncturing when air was injected at a speed of 2 cc / sec by inserting a syringe needle was measured to be 1.2 kg. / cm ² , and had sufficient pressure resistance.

〔The invention's effect〕

As described above, according to the present invention, it is possible to manufacture a sealed container having a structure in which the lid can be easily opened with a smooth peel feeling while always maintaining sufficient pressure tightness.

Therefore, it can be widely applied as a container for packaging all kinds of foods.

[Brief description of the drawings]

1 is a sectional view showing a container body, FIG. 2 is a plan view of a container showing a state in which a punching slit having a non-punched portion is intermittently provided in a container flange portion, and FIG. 3 is FIG. 4 is a cross-sectional view showing a state where a resin is injection-molded on the outer peripheral surface of FIG. 3, and FIG. 5 shows a sealed container of the present invention in which a lid material is heat-sealed. FIG. 6 is a partially enlarged cross-sectional view showing a state at the time of opening, and FIG. 7 is a plan explanatory view showing a state of the container at the time of opening. DESCRIPTION OF SYMBOLS 1 ... Flange part, 2 ... Seal layer (container) 3 ... Adjacent layer, 4 ... Non-punched part 5 ... Punched slit, 6 ... Injected resin layer 7 ... Lid material, 8 ... Seal layer surface ( Lid) X: Force in peel direction

Claims (1)

(57) [Claims] 1. A sealing material comprising at least two container flange portions having a lamination strength of 300 to 2000 g / 15 mm between a sealing layer and an adjacent layer facing the sealing layer and a lid member having a sealing layer surface, wherein the sealing strength is not less than the lamination strength. In producing a sealed container by heat sealing in a state, after interposing a punching slit having a non-punched portion intermittently in advance along the inner edge of the container flange portion, the outermost layer of the container is bonded to the outer peripheral portion of the container. Injection molding of resin that does not adhere or hardly adhere to the sealing layer surface of the lid material, forming the layer, filling the punching slit part, and then heat sealing the peripheral side of the punching slit and the sealing layer surface of the lid material. Manufacturing method of a sealed container.