JPH06183432A - Paper container for liquid - Google Patents

Abstract

PURPOSE:To stabilize the sealing conditions of the heat-adhesive parts of a paper container, by providing an air vent hole, at least reaching the base board, at the outermost resin layer constituting the heat-adhesive part. CONSTITUTION:A paper container is provided with a packing material 7 composed of inner film 2 made of polyethylene resin, drawn plastic film 3 made of drawn polyester resin, adhesive 4, base paper 5, superficial layer 6 made of polyolefin resin as a layer structure of this order from the inside of container. A plurality of air vent slit holes 10 reaching the base paper on the superficial resin layer 6 of the sticking area as the external side at the side seal 8. The air vent holes are provided earlier than the side seal is applied. The steam generated from the base paper 5 due to the side seal heat when applying the side seal, is removed outward through the air vent holes 10. And hence, that prevents the inner film 2 from separating from the base paper 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid paper container for containing juice or the like.

[0002]

2. Description of the Related Art Conventionally, a paper container of this type is assembled from a blank state and a side-sealing portion is heat-sealed to obtain a tubular sleeve. It is manufactured through the process of injection, formation of the top (top seal), etc.

[0003]

The packaging material used as these paper containers is a laminated body mainly composed of a base paper and synthetic resin films and the like stacked on top of each other. Some have an aluminum foil layer, and some do not (a layered packaging material having an aluminum foil layer has been used, mainly when barrier properties to the outside world are required).

By the way, the one having the aluminum foil layer in the constitution of the interior film in the packaging material is advantageous for heat dissipation through the aluminum foil layer at the time of sealing the side seal portion, the top seal portion and the bottom seal portion. However, in the case of a packaging material which does not include this aluminum foil layer having excellent thermal conductivity and heat resistance in the constitution of the interior film, for example, when looking at the side seal portion, the following phenomenon may occur. 1. Since it does not contain an aluminum foil layer, the side seal heat does not conduct to the surroundings and is localized in the side seal part, and the moisture contained in the base paper is generated as water vapor, and this generated water vapor is the interior film. Expands between the base paper and the base paper, and the interior film separates from the base paper and rises. 2. Further, when this phenomenon becomes remarkable, the heat-melted interior film does not withstand the expansion of water vapor and bursts because it does not include the aluminum foil layer having excellent heat resistance. As a result of this phenomenon, when a paper container is manufactured using a packaging material that does not include an aluminum foil layer in the composition of the interior film, a side seal that is more stable than a paper container that uses a packaging material having an aluminum foil layer. It was difficult to obtain the condition, and there was concern that the side seals would peel off and the contents would leak.

In view of the above-mentioned circumstances, the present invention has an object to escape the steam generated from the base paper to the outside through the exterior film when sealing the heat-bonded portion, and to solve the problem. The purpose is to stabilize the sealed state of.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and is made of a material having a laminated constitution mainly composed of paper having thermoplastic resin layers on both inner and outer surfaces, and is desired. In a liquid paper container having a heat-bonded portion for heating and bonding when forming a container, a vent hole reaching at least the base paper is formed in the resin layer on the outermost surface of the heat-bonded portion. A liquid paper container characterized by being provided is provided to solve the above problems.

[0007]

In the present invention, the water vapor generated from the base paper at the time of the side seal, the top seal and the bottom seal is
It will escape to the outside through the ventilation holes in the surface resin layer (exterior film) that reaches the base paper.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below by exemplifying a side seal portion based on an embodiment shown in FIGS. In the figure, reference numeral 1 denotes a liquid paper container shown in the form of a sleeve. This paper container 1 has a layer structure from the inner side of the container. 4, the base paper 5, and the packaging material 7 in which the surface resin layer 6 is a polyolefin resin.

Then, as shown in FIG. 2, the surface resin layer 6 of the bonding margin 9 on the outer side of the side seal portion 8 is formed.
In addition, a plurality of slit-shaped ventilation holes 10 reaching the base paper 5 are provided over the side seal portion 8. This vent hole 10 is already provided before the side seal, and at the time of the side seal, steam generated from the base paper 5 is allowed to escape to the outside through the vent hole 10 due to the heat of the side seal. And the base paper 5 are not separated from each other. The vent hole of the side seal part may be left as it is, but if the resin is laminated on this side seal part after the side seal part, even if the resin is cooled by a shower after the filling seal, the water content of the vent hole is reduced. Through this, it becomes possible to reliably prevent the problem of penetrating the base paper and lowering the durability.

The above-mentioned vent holes allow the generated water vapor to escape to the outside immediately and efficiently. However, since it is required that water droplets and the like do not enter from the outside world, the shape thereof may be circular pores or groove slits. It doesn't matter, but the opening width is 5
20μ is desirable.

As a method of forming the ventilation hole, a metal protrusion or a blade is provided at a portion corresponding to the bonding margin of the blank punching die so that the front resin layer is pushed open to open it or the sheet resin after printing is finished. There is a method of irradiating a layer with a laser beam or the like to melt and open the layer.

A comparison between the conventional paper container and the paper container of the present invention is shown below. Conventional example A blank was prepared by punching a packaging material having the following configuration. (Outside) Polyethylene (20μ) / Base paper (350g / m
² ) / Polyethylene (40μ) / Polyester film (12μ) / Polyethylene (50μ) (inside) -Polyethylene: High pressure method low density polyethylene, density 0.
920 MFR5.3 Polyester film: polyethylene terephthalate biaxially stretched film The blanks were side-sealed with a gas flame type frame sealer to prepare a paper container. When colored turpentine oil was applied to the inner polyethylene of the side seal portion of this paper container, it was confirmed that the turpentine oil penetrated to the paper surface and the polyester film was melted by heat to generate pinholes.
Moreover, the sealing strength of the side seal portion is 0.9 kg / 15.
mm was lower than that of a normal paper container (having an aluminum foil layer).

Example 1 The packaging material had the same layer structure as the conventional example. However, when punching Granks, a metal blade (blade width 2
At 5 μ), three slit-shaped (discontinuous) ventilation holes were formed in the surface resin layer of the bonded portion (outer side) to be the side seal portion at an interval of 5 m / m in the vertical direction. The actually measured opening width of the ventilation hole was 15 μm. When this blank was side-sealed in the same manner as in the conventional example and the side-sealed portion was observed, pinholes were not confirmed, and the interior film was not peeled from the base paper or floated. Furthermore, the sealing strength of the side seal part is 3.8 kg.
/ 15mm and normal paper container (with aluminum foil layer)
The same numerical value was obtained, and a good side seal state was obtained.

Example 2 The layer structure of the packaging material was the same as that of the conventional example. However, when punching the granks, the metal protrusions (outer diameter 20 μ) provided on the die are 9 pieces per square cm on the surface resin layer of the bonding portion (outer side) that becomes the side seal portion (outer side). A total of about 400 small holes were drilled at the rate of. The measurement of the opening diameter of the fine hole was 10 μm when actually measured. When this blank was side-sealed in the same manner as in the conventional example and the side-sealed portion was observed, pinholes were not confirmed, and the interior film was not peeled from the base paper or floated. Furthermore, the sealing strength of the side seal part is 4.2.
Kg / 15 mm and a value similar to that of an ordinary paper container (having an aluminum foil layer) were obtained, and a good side-sealed state was obtained.

[0015]

As described above, according to the present invention,
Ventilation holes that reach the base paper are provided in the surface resin layers of the heat seal parts such as the side seal part, the top seal part, and the bottom seal part, so that the water vapor generated from the base paper at the time of side sealing etc. escapes from the vent holes to the outside. Therefore, the interior film does not peel off or rise from the base paper. Further, since the pressure of the generated steam is small and not large, it does not burst even when the interior film is in a heat-melted state in the side seal or the like. Therefore, it is possible to obtain a stable side seal part similar to a paper container made of a packaging material having an aluminum foil layer, the side seal part is peeled off, and the contents are prevented from leaking. Is.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a liquid paper container according to the present invention in a sleeve state.

FIG. 2 is an explanatory diagram showing a cross section of a main part of one embodiment.

[Explanation of symbols]

 1 ... Liquid paper container 2 ... Interior film 3 ... Stretched plastic film 4 ... Adhesive 5 ... Base paper 6 ... Surface resin layer 7 ... Packaging material 8 ... Side seal part 9 ... Bonding margin 10 ... Vent hole

Claims (1)

[Claims] 1. A heat for bonding by heating when forming a container, as well as providing a crease line at a desired position, which is made of a laminated material mainly composed of paper having thermoplastic resin layers on both inner and outer surfaces. A liquid paper container having an adhesive portion, characterized in that a vent hole reaching at least the base paper is provided in an outermost resin layer forming the thermal adhesive portion.