DE69500460T2 - Structure of a pouring spout for paper box, paper box with spouting opening and manufacturing method of such a spouting opening - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

The present invention relates to a pouring opening structure for a paper carton, to a paper carton having the pouring opening, and to a method for producing such a pouring opening.

2. State of the art

Recently, small-volume paper cartons have been widely used in the field of beverages such as fruit juices, coffee, soup, and fermented milk drinks because they are handy and can be easily removed after their use is finished. Some of these paper cartons have a pouring hole sealed with a strip tape that is peeled off to open the carton. For the paper carton of the type described, various studies have been made to prevent the contents of the carton from entering the inner peripheral surface defining a pouring hole or pouring opening. An example is disclosed in U.S. Patent 4,595,116, the structure of which is illustrated in Figure 16. According to this prior art, the pouring opening 1 has a laminate base material 2 (a paper-based laminate). A hole 3 is formed in the laminate base material 2 by piercing it to form a hole of a predetermined shape. Thermoplastic resin or the like is then laminated on one surface 4 facing the outside of the carton made of the laminate base material 2 and on the other surface 5 facing the inside of the carton to form an outer waterproof layer 6 and an inner waterproof layer 7, respectively. A pouring opening 9 is provided at an attached portion 8 where the waterproof layers 6 and 7 are secured together within the above-mentioned pouring hole. A strip tape 10 is removably attached to the outer waterproof layer 6 to cover the pouring opening 9.

Laminate materials, which form the main body of the carton with the waterproof layers provided on the outer and inner surfaces of the above-mentioned laminate base material, have a laminated layer structure made of selected synthetic resin or metal foil. The selection and combination of these materials enables the carton to have the desired properties such as waterproof properties, water resistance, shading and gas impermeability properties.

However, in such a structure in which the waterproof layers are attached to each other in the pouring hole and one pouring hole is covered with a strip tape, both waterproof layers attached by lamination cover the inner peripheral surface defining the pouring hole. Accordingly, a small hole or a thinner portion of the layer may be formed depending on the state of the inner peripheral surface defining the pouring hole at the time of heat sealing the synthetic resins of the inner and outer waterproof layers. This often results in insufficient sealing in the inner peripheral surface defining the hole and allows the contents of the carton to enter the inner peripheral surface through a gap formed at the attached portion. In order to obtain the gas barrier properties around the pouring hole having no laminate base material laminated thereon, a laminate film may be formed by an aluminum foil and an oriented polyester film used as the components of the above-mentioned inner and outer layers, taking into account the gas barrier properties and the strength of the film. However, these components typically have poor heat sealing properties with respect to each other, so that the thermoplastic resin must be laminated on the above laminate film, which complicates the layer structure of the entire laminate film and increases the cost. Although the sealing properties by providing a larger sealing strength, a very large sealing strength may cause the strip tape to be torn off together with the outer waterproof layer. As a result, the pouring opening may be enlarged when the strip tape is peeled off. In addition, only poor waterproof properties may be achieved.

The above mentioned problem can be solved with a lower sealing strength. However, the lower sealing strength may cause problems of leakage of the contents or poor retention properties.

EP 0 312 816, which represents the closest prior art, discloses a pouring opening structure for a liquid container comprising a laminate base material, an outer waterproof layer and an inner waterproof layer, each formed on opposite surfaces of the laminate base material. Both the base material and both waterproof layers are provided with a pouring hole which is closed by a tape attached to the outer surface of the outer waterproof layer. Furthermore, a partial covering film having a pouring hole smaller than the pouring hole of the laminate base material is attached to the inner waterproof layer and the tape so as to cover the peripheral end surfaces of the laminate base material which form the pouring hole.

Concerning the above problems, the present invention aims to simplify the structure of the pouring port by using a partial covering film to cover the inner peripheral surface defining the hole of the laminate base material; and an object of the present invention is to easily obtain such a pouring port so that no content enters the inner peripheral surface defining the hole.

SUMMARY OF THE INVENTION

The present invention is therefore made in consideration of the above-mentioned problems, and in order to solve the above-mentioned problems, there is provided a pouring opening structure of a paper carton comprising: a Laminate base material; an outer waterproof layer formed on one surface facing the outside of the carton made of the laminate base material, the laminate base material and the outer waterproof layer being provided with a hole formed therein and extending therethrough; an inner waterproof layer formed on the other surface facing the inside of the carton made of the laminate base material, the inner waterproof layer extending over the hole and being provided with an inner waterproof pouring hole formed therein and extending therethrough, the inner waterproof pouring hole being smaller than the hole; a partial covering film attached to the outer waterproof layer along the circumference of the hole such that the partial covering film covers the hole by extending over the pouring hole, the partial covering film being provided with a partial covering film pouring hole formed therein and extending therethrough, the partial covering film pouring hole being smaller than the hole and corresponding to the inner waterproof pouring hole, the inner waterproof layer and the partial covering film being attached as an attached portion to the circumference of the inner waterproof pouring hole and the partial covering film pouring hole; an opening portion provided in the pouring hole and defined by the edge of the attached portion, the attached portion covering the inner peripheral surface defining the hole; and a strip tape detachably attached to the partial covering film, the opening portion being covered with the strip tape.

According to another aspect of the present invention, there is provided a pouring opening structure of a paper carton comprising: a laminate base material; an outer waterproof layer formed on one surface facing the outside of the carton made of the laminate base material; an inner waterproof layer formed on the other surface facing the inside of the carton made of the laminate base material, the laminate base material, the outer waterproof layer and the inner waterproof layer being provided with a hole formed therein and passing therethrough; an outer partial covering film adhered to the outer waterproof layer is disposed along the periphery of the pouring hole such that the outer partial covering film covers the hole by extending over the hole, the outer partial covering film being provided with an outer partial covering film hole formed therein and extending therethrough, the outer partial covering film pouring hole being smaller than the pouring hole; an inner partial cover film attached to the inner waterproof layer along the periphery of the hole such that the inner partial cover film covers the hole by extending over the pouring hole, the inner partial cover film being provided with an inner partial cover film pouring hole formed therein and extending therethrough, the inner partial cover film pouring hole being smaller than the hole and corresponding to the outer waterproof pouring hole, the outer and inner partial cover films being attached as an attached portion to the periphery of the outer and inner partial cover film pouring holes; an opening portion provided in the hole and defined by the edge of the attached portion, the attached portion covering the inner peripheral surface forming the hole; and a strip tape detachably attached to the outer partial cover film, the opening portion being covered with the strip tape.

Thus, in the present invention, the inner peripheral surface defining the hole is covered with the attached portion formed of the extended inner waterproof layer and window-shaped adhesive film. Alternatively, the inner peripheral surface defining the hole is covered with the attached portion formed of the outer and inner partial covering films. These structures prevent the contents of the container from penetrating into the above inner peripheral surface. Accordingly, a layer film having gas barrier properties and strength can be used as the partial covering film without a substantial increase in the manufacturing cost of the whole body of the carton, since a partial covering film is to be attached only along the hole. As mentioned above, the strip tape covers the opening portion placed inside the pouring hole, the opening Section becomes visible by pulling off the strip tape to open the pouring opening.

Further, an annular heat-sealed varnish layer may be provided on the outer surface of the outer partial covering film, and the strip tape may be detachably attached to the partial covering film through the heat-sealed varnish layer.

The partial covering film may have a multilayered structure. The inner waterproof layer extending over the hole and the inner partial covering film may be formed in a multilayered structure including a film having gas barrier properties. In addition, the inner and outer partial covering films may be formed in a multilayered structure including a film having gas barrier properties.

The outer partial covering film may be formed in a multilayer structure including a film having a large mechanical strength. It may be formed in a multilayer structure including layers to be separated from each other at the time of peeling off the strip tape or in a multilayer structure including a white-colored film.

In the present invention, there is also provided a paper carton in which the pouring opening of the above-mentioned structure is provided in the upper surface of the paper carton having a brick shape. Alternatively, the pouring opening of the above-mentioned structure may be provided in the inclined upper surface of a paper carton having a gable-shaped upper end. Further, the pouring opening of the above-mentioned structure may be provided in the upper surface of the paper carton having a cylinder trunk portion.

Furthermore, in the cylindrical paper carton according to the present invention, the circular upper surface has an outer flange portion, and the strip band extends outward from the pouring opening beyond the outer flange portion. In addition, in the tile-shaped, gable-top-shaped or cylindrical paper carton, the strip band has a take-out portion at the distal end thereof.

According to still another aspect of the present invention, there is provided a method of manufacturing a pouring opening of a paper carton, comprising the steps of: laminating an outer waterproof layer on one surface facing the outside of the carton made of a laminate base material; forming a pouring hole passing through the laminate base material and the outer waterproof layer; laminating an inner waterproof layer on the other surface facing the inside of the paper carton made of the laminate base material where the hole is formed; applying a partial covering film larger than the hole from the exposed portion of the inner waterproof layer through the hole to a flange portion of the outer waterproof layer around the hole, thus covering the inner peripheral surface defining the hole with the inner waterproof layer and the partial covering film; forming an opening portion passing through the partial covering film and the inner waterproof layer into the area where the partial covering film is attached to the inner waterproof layer; and removably attaching a strip tape to the partial covering film to cover the opening portion with the strip tape. Another aspect of the present invention includes the steps of: laminating an outer waterproof layer and an inner waterproof layer on one surface facing the outside of the paper carton made of a laminate base material and the other surface facing the inside of the paper carton; forming a pouring hole passing through the laminate base material, the outer waterproof layer and the inner waterproof layer; Placing partial covering films outside and inside of the hole, the partial covering films being larger than the hole and being attached to each other in the hole, the partial covering films also being attached to the waterproof layers around the hole to cover the inner peripheral surface with the inner and outer partial covering films; forming an opening portion extending through the partial covering films into the area where the partial covering films are attached to each other; and removably attaching a strip tape to the partial Cover film to cover the opening portion with the strip tape. According to this method of manufacturing the pouring opening, the inner peripheral surface defining the hole is covered by the attached portion formed of the extended inner waterproof layer and the window-shaped adhesive film. As another option, the inner peripheral surface defining the hole is covered by the attached portion formed of the outer and inner partial cover films. These structures prevent the contents of the container from entering the above inner peripheral surface. When the pouring portion located in the pouring hole is covered with the strip tape, the pouring opening is sealed with the strip tape.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a view for describing an embodiment of a pouring opening structure for a paper carton according to the present invention;

Fig. 2 is a view illustrating the steps for manufacturing the pouring opening structure of Fig. 1, in which (A) is a view showing a laminate base material, (B) is a view showing the laminate base material with an outer waterproof layer formed thereon, (C) is a view of the laminates in which a hole is formed, (D) is a view showing the laminate base material with an inner waterproof layer formed thereon, (E) is a view showing a partial covering film attached to the laminates, (F) is a view showing a pouring portion formed through the laminates, and (G) is a view showing the pouring opening with a strip tape attached thereto;

Fig. 3 is a view for describing another embodiment of a pouring opening structure for a paper carton according to the present invention;

Fig. 4 shows the manufacturing process of the pouring opening structure of Fig. 3, in which (A) is a view showing a laminate base material, (B) is a view showing the laminate base material with inner and outer waterproof layers formed thereon, (C) is a view of the laminates, in which a hole is formed, (D) is a view showing a partial covering film attached to the laminates, (E) is a view showing a pouring portion formed through the laminates, and (F) is a view showing the pouring opening with a strip tape attached thereto;

Fig. 5 is a view for describing the pouring opening having a heat-sealed varnish layer;

Fig. 6 is a view for describing the pouring opening with a partial covering film on which a gas barrier film layer is provided;

Fig. 7 is also a view for describing the pouring port with a partial covering film on which a gas barrier film layer is provided;

Fig. 8 is a view for describing the pouring opening with a partial covering film on which a strong film layer is provided;

Fig. 9 is a view for describing the pouring opening without the strip band;

Fig. 10 is also a view for describing the pouring opening with a partial covering film on which a strong film layer is present;

Fig. 11 is a view for describing the pouring opening with a partial covering film on which a white layer is provided;

Fig. 12 is a view for describing a cylindrical paper carton;

Fig. 13 is a view showing a cross section of the cylindrical paper board;

Fig. 14 is a view for describing a brick-shaped paper carton;

Fig. 15 is a view for describing a gable roof-shaped paper carton

Fig. 16 is a view for describing a prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Next, the present invention will be described in more detail in connection with its embodiments illustrated in the drawings. In the illustrations, like components and parts are designated by like reference numerals as the conventional ones in Fig. 16, and their explanation will be skipped.

A laminate base material 2 for a paper board is formed by laminated synthetic resin or synthetic resin film on a paper board serving as a base material. A metal film layer, a metal coated layer or a metal oxide coated layer may be formed thereon depending on the applications of the paper board. For example, the laminate base material 2 consists of a paper board layer (220 g/m²), a polyethylene layer (20 µm thick), a polyethylene layer (15 µm thick), a biaxially oriented polyethylene terephthalate film layer (12 µm thick) and a silicon oxide coated thin layer (400 Å thick) laminated in this order from the outside of the paper board to the inside thereof.

In the structure of a pouring opening 1 according to the present invention, as illustrated in Fig. 1, a hole 3 is provided through the above-mentioned laminate base material 2 and an outer waterproof layer 6 laminated on a surface 4 facing the outside of the paper board of laminate base material 2. The outer waterproof layer 6 may be, for example, a single low density polyethylene layer formed from extrusion laminate 60 µm thick. On the inside of the hole 3, an inner waterproof layer film 7a serving as a laminated inner waterproof layer 7 extends over the hole 3. In the inner waterproof layer 7, an inner waterproof layer pouring hole 12 smaller than the hole 3 is formed. The inner waterproof layer 7 comprises, for example, an adhesive resin layer, a gas barrier film having gas barrier properties, and a laminate film comprising laminated layers of synthetic resin films laminated in this order from the laminate base material side. However, the inner waterproof layer 7 may be a single layer of polyethylene, such as low density polyethylene or linear low density polyethylene. If necessary, a polyester copolymer may be used for the single layer of this inner waterproof layer 7.

Reference numeral 11 in the illustration denotes a partial covering film. The partial covering film 11 is attached to the portion around the pouring hole in the outer waterproof layer 6 and extends to the inside of the pouring hole. A partial covering film pouring hole 13 is formed in the partial covering film 11, which pouring hole 13 is smaller than the hole 3 and corresponds to the inner waterproof layer pouring hole 12. As will be described later, the partial covering film 11 may be made of a film having a multi-layer structure. However, the partial covering film 11 may be a single layer of polyethylene such as low-density polyethylene or linear low-density polyethylene. If necessary, a polyester copolymer may be used for the single layer of this partial covering film 11.

At the pouring opening 1, flange portions 12a and 13a of the pouring holes 12 and 13 in the inner waterproof layer and the partial covering film are fixed to each other as an attached portion to define an opening portion 9 inside the hole 3. An inner peripheral surface 14 defining the hole 3 is covered with the partial covering film 11 and the inner waterproof layer 7 (inner waterproof layer film) whose flange portions 12a and 13a are fixed to each other.

As mentioned above, the inner peripheral surface 14 is covered with the protruding portions of the inner waterproof layer 7 and the partial covering film 11. These protruding portions, or the above-mentioned flange portions 12a and 13a, are fixed to each other as the attached portion. Such a structure prevents the contents of the paper carton from penetrating into the inner peripheral surface 14 defining the hole 3. With respect to the partial covering film 11, a strip tape 10 is detachably attached to the outer periphery of the partial covering film 11 as in the prior art described above. The strip tape 10 thus covers the opening portion 9.

The pouring port 1 having the above-mentioned structure can be manufactured by the following steps as illustrated in Fig. 2. First, the laminate base material 2 is provided in a sheet form (A). The outer waterproof layer 6 is formed on a surface 4 facing the outside of the paper board of laminate base material 2 by directly laminating a desired resin or a laminate film formed of desired resin layers (B). After the above-mentioned waterproof layer 6 is formed, a hole 3 is formed through the laminate base material 2 and the outer waterproof layer 6 at a predetermined position (C).

Next, on the other surface 5 facing the inside of the paper board of laminate base material 2, an inner waterproof layer 7 is formed by laminating an inner waterproof layer film having layers of desired resin and a barrier material so that the above inner waterproof layer 7 extends over the hole 3 (D). Then, the partial covering film 11 larger than the hole 3 to cover the hole 3 is attached by the head sealing technique from the exposed portion of the inner waterproof layer 7 through the hole 3 to the outer waterproof layer 6 around the flange portion of the pouring hole (E). This partial covering film 11 is a laminate film in which a thermoplastic resin represented by polyethylene resin is applied at least on its surface and contacts the inner waterproof layer film 7a to ensure good heat sealing properties between the partial covering film 11 and the upper resin layer of the inner waterproof layer film constituting the inner waterproof layer 7.

After the attached portion 8 is formed inside the hole 3 by attaching the partial covering film 11 to the inner waterproof layer 7, the opening portion 9 is formed by the partial covering film 11 and the inner waterproof layer 7 in this attached portion 8 (F). No gap is formed at the flange portion of the opening portion 9 because the flange portion 13a of the partial covering film 11 and the flange portion 12a of the inner waterproof layer 7 by heat. This heat sealing prevents the contents from entering the inner peripheral surface which defines the pouring hole.

After the opening portion 9 is formed in the above-described manner, a paper carton is made of this laminate material. More specifically, an "empty carton" to be formed into the paper carton is filled with the contents using a filling machine. After the filling is completed, a strip tape 10 as shown in (G) is heat-sealed to the partial covering film 11 at the position corresponding to the outer waterproof layer 6 (outer peripheral portion of the partial covering film 11) to cover the opening portion 9. As a result, the opening portion 9 to be opened is provided and the paper carton is completely formed. Alternatively, the strip tape may be sealed to the empty carton in advance, before filling the contents. The strip tape 10 has, at least on the side facing the partial covering film 11, a layer that allows the strip tape to be heat sealed to the partial covering film 11.

According to the above embodiment, the partial covering film extending inward from the outside of the paper carton is attached to the inner waterproof layer to cover the inner peripheral surface defining the pouring hole. However, the partial covering films may extend inward and outward from the paper carton and be attached to each other in the pouring hole to cover the inner peripheral surface defining the pouring hole.

Figures 3 and 4 show the structure of the pouring opening 1 with partial covering films attached to each other from the inside and outside of the paper carton. As shown in Fig. 3, a hole 3 is provided through the above-mentioned laminate base material 2, an outer waterproof layer 6 laminated on one surface 4 facing the outside of the paper carton made of laminate base material 2, and an inner waterproof layer 7 laminated on the other surface 5 facing the inside of the paper carton made of laminate base material 2. The outer and inner waterproof Layers 6 and 7 can, for example, be a low density polyethylene layer formed by extrusion laminate 60 µm thick.

A partial cover film 11 is attached to the outer waterproof layer 6 at a position along the circumference of the pouring hole to cover the hole 3 from the outside of the paper carton. In addition, another partial cover film 15 is attached to the inner waterproof layer 7 at the position along the circumference of the pouring hole to cover the hole 3. Further, the inner and outer partial cover films 11 and 15 are attached to each other within the hole 3. Then, at the attached portion of the partial cover film, a pouring hole 13 of the partial cover film smaller than the hole 3 is formed in the outer partial cover film 11 and a pouring hole 16 of the partial cover film smaller than the hole 3 is formed in the inner partial cover film 15. Both pouring holes 13 and 16 in the above partial covering films overlap and communicate with each other. The partial covering films 11 and 15 may be made of a film having a multi-layer structure. However, the partial covering films 11 and 15 may be a single layer of polyethylene such as low-density polyethylene or linear low-density polyethylene. If necessary, a polyester copolymer may be used for the single layer of these partial covering films 11 and 15.

As shown in the illustration, flange portions 13a and 16a of the pouring holes 13 and 16 in the outer and inner waterproof layers, respectively, are fixed to each other as an attached portion to define an opening portion 9 inside the hole 3. An inner peripheral surface 14 is covered with the partial covering films 11 and 15 whose flange portions 13a and 16a are fixed to each other. This structure ensures a tight seal against the inner peripheral surface 14 forming the hole 3.

As mentioned above, the inner peripheral surface 14 is covered with the protruding portions of the partial covering films 11 and 15. These protruding portions, or the above-mentioned flange portions 13a and 16a, are considered to be the attached portion. Such a structure prevents the contents of the paper carton from penetrating into the inner peripheral surface 14 defining the hole 3. Regarding the partial covering film 11, a strip tape 10 is detachably attached to the outer periphery of the partial covering film 11 as in the above-mentioned embodiment.

As an example, the strip tape 10 may be formed from layers including a biaxially oriented polyethylene terephthalate film layer (12 µm thick), a silicon oxide coated thin film layer (400 Å thick), and a polyethylene layer (40 µm thick) laminated in that order from the outside of the paper board. As another possibility, the strip tape 10 may be formed from layers including a biaxially oriented polyethylene terephthalate film layer (12 µm thick), an aluminum layer (50 µm thick), and a polyethylene layer (40 µm thick) laminated in that order from the outside of the board.

The pouring port 1 having the above-mentioned structure can be manufactured by the following steps as shown in Fig. 4. First, the laminate base material 2 is provided in a sheet form (A). The outer and inner waterproof layers 6 and 7 are formed on one surface 4 facing the outside of the paper board made of the laminate base material 2 and on the other surface 5 facing the inside of the paper board made of the laminate base material 2 by directly laminating a desired resin or a laminate film made of desired resin layers to provide the laminate material (B). After the above-mentioned waterproof layers 6 and 7 are formed, a hole 3 is formed through the laminate base material 2 and the outer and inner waterproof layers 6 and 7 at a predetermined position (C).

Next, the partial covering films 11 and 15 larger than the hole 3 are attached from the inside and outside of the paper board to cover the hole 3, and the partial covering films 11 and 15 are attached to each other inside the hole 3. The outer partial covering film 11 is attached to the outer waterproof layer 6 at the periphery of the hole 3. while the inner partial covering film 15 is attached to the inner waterproof layer 7 at the periphery of the pouring hole (D). Then, an opening portion 9 is formed by the attached portion 8 of the partial covering films 11 and 15 inside the hole 3 (E). No gap is formed at the flange portion of the opening portion 9 because the flange portions 12a and 16a of the partial covering films 11 and 15 are fused by heat. This heat sealing prevents the contents from entering the inner peripheral surface defining the pouring hole. These partial covering films 11 and 15 are made of such synthetic resin that has good sealing properties with respect to each other and the waterproof layers 6 and 7.

After the opening portion 9 is formed in the above-described manner, a paper carton is made of this laminate material. (The strip tape 10 may be previously sealed over the opening portion to cover it with the strip tape before the paper carton is formed.) More specifically, an "empty carton" to be formed into the paper carton is filled with the contents using a filling machine. After the filling is completed, a strip tape 10 as shown in (F) is heat-sealed to the partial covering film 11 at the position corresponding to the outer waterproof layer 6 (outer peripheral portion of the partial covering film 11) to cover the opening portion 9. As a result, the opening portion 9 to be opened is provided and the paper carton is completely formed.

In order to ensure easy opening of the pouring opening 1, as shown in Fig. 5, an annular heat-sealed varnish layer 17 is provided on the outer surface of the outer partial covering film 11, which corresponds to the position where the strip tape is to be attached. The strip tape 10 can be attached to the partial covering film 11 via this heat-sealed varnish layer 17. The heat-sealed varnish layer 17 can be formed by applying a heat-sealed varnish made of nitrocellulose resin to the partial covering film 11 by means of the cliche printing technique.

The present invention has thus been described in connection with the partial covering films 11 and 15 in the pouring hole 1 formed as a single layer. However, in order to make the partial covering films more suitable for the portion of the pouring hole that does not have a laminate base material having gas barrier properties and water resistance, a multilayer film designed with various properties such as gas barrier properties and water resistance in mind may be used as a partial covering film.

6 and 7 show another embodiment of the present invention for improving the gas barrier properties at the pouring port 1. In the structure of the pouring port, the inner peripheral surface defining the pouring hole is covered by a combination of the partial covering film 11 extending from the outside of the paper board and the inner waterproof layer 7 attached thereto, as shown in Fig. 6. The inner waterproof layer 7, which is formed by laminating the inner waterproof film 7a on the surface 5 of the laminate base material 2, is a laminate film formed of an adhesive resin layer 7b, a gas barrier film 7c having gas barrier properties, and a synthetic resin film layer 7d, which are laminated in this order from the side of the laminate base material 2. The gas barrier film layer 7c may be formed of a silicon oxide coated thin film and an aluminum thin film. While the outer partial covering film 11 made of the multilayer laminate film is composed of an adhesive resin layer 11a, a gas barrier film layer 11b having gas barrier properties, and a synthetic resin film layer 11c laminated in this order as viewed from the laminate base material 2 side. The gas barrier film layer 11c may be formed of a silicon oxide coated thin film and an aluminum thin film similar to the above gas barrier film layer 7c. Then, the adhesive resin layer 7b of the inner waterproof layer film 7a and the adhesive resin layer 11a of the partial covering film 11 in the inner portion of the hole 3 are heat-sealed. As a result, the inner peripheral surface 14 is covered with the inner waterproof layer film 7a and the partial covering film 11. The strip tape 10 is constructed to fulfill a barrier function such as shading or gas barrier properties, and is manufactured by laminating a barrier layer 10a and an adhesive resin layer 10b.

The inner waterproof layer film 7a and the partial covering film 11 covering the inner peripheral surface 14 defining the pouring hole both have such gas barrier properties. Accordingly, oxygen arriving at the inner peripheral surface 14 defining the pouring hole after passing through the outer waterproof layer 6 and the laminate base material 2 will not pass through the inner waterproof layer film 7a and the partial covering film 11. As a result, it is possible to prevent the oxygen from penetrating into the paper board. The strip tape 10 itself also has gas barrier properties, and no oxygen can pass through this strip tape 10.

In the embodiment shown in Fig. 7, an outer waterproof layer 6 is laminated on one surface 4 outside the paper carton. At the same time, the inner waterproof layer 7 is formed on the other surface 5 inside the paper carton by laminating the inner waterproof layer film 7a having gas barrier properties. Then, a hole 3 is drilled through the laminate materials consisting of the outer waterproof layer 6, the laminate base material 2 and the inner waterproof layer 7, with the partial cover films 11 and 15 attached thereto inside and outside the paper carton to cover the inner peripheral end face 14 defining the pouring hole.

Both the outer partial covering film 11 and the inner partial covering film 15 are the multilayer laminate films having the gas barrier properties, which are prepared by laminating adhesive resin layers ha and isa, gas barrier film layers 15b and 15b having the gas barrier properties, and synthetic resin film layers 11c and 15c, in this order from the side of the laminate base material. Similarly to the above-mentioned embodiment, the inner peripheral surface defining the pouring hole is covered with the partial covering films 11 and 15 having the gas barrier properties. Therefore, it is possible to prevent the contents from penetrating into the base material, and the oxygen which has arrived at the inner peripheral surface 14 of the pouring hole after passing through the outer waterproof layer 6 and the laminate base material 2 can be prevented from penetrating into the paper board.

Regarding the partial covering film 11 provided outside the paper carton, if the mechanical strength of the film is improved, it is possible to prevent the resin from wearing off when the strip tape is peeled off. Figs. 8 and 9 show still another embodiment of the pouring opening 1 in which an inner peripheral surface 14 defining the pouring hole is covered with the outer partial covering film and the inner waterproof layer 7.

In this embodiment, the partial covering film 11 is the laminate film having a multilayer structure, namely, an adhesive resin layer 11a, a tough film layer 11d constituting a core portion of the partial covering film 11, and a synthetic resin film layer 11c, which are laminated in this order from the side of the laminate base material 2. The tough film layer 11d may be formed of, for example, a polyester film or a nylon film.

Further, this film layer lid is made to have enough toughness to remain on the side of the laminate base material 2 without being torn off together with the strip tape 10 at the time of opening the pouring opening 1, and it is arranged so that the tearing can occur in the portion of the layer above the film layer lid at the time of tearing off the strip tape 10. Likewise, the film layer 11d is made to remain on the side of the laminate base material 2 at the time of tearing off the strip tape 10. Therefore, the strip tape 10 can be properly peeled off, and the resin surface (synthetic resin layer 11c) around the window-shaped film 11 is removed at the time of tearing off the strip tape is not pulled away. Accordingly, the appearance of the pouring opening is not damaged.

Fig. 10 shows the pouring opening covered with the inner and outer partial covering films 11 and 15. Also in this embodiment, similar to the above, the partial covering film 11 is a multilayer laminate film having the following structure: an adhesive resin layer 11a, a tough film layer 11d which is a core portion of the partial covering film 11, and a synthetic resin layer 11c which are laminated in this order from the side of the laminate base material 2. The tough film layer 11d may be formed of, for example, a polyester film. Then, the film layer 11d is arranged to remain on the side of the laminate base material 2 at the time of tearing off the strip tape 10, the strip tape 10 can be properly torn off, and the resin surface (synthetic resin layer 11c) around the window-shaped film 11 is not peeled off at the time of tearing off the strip tape. Accordingly, no damage is caused to the appearance of the pouring port.

As described above, the partial covering film 11 provided outside can be formed as the multilayer laminate film including a tough film of high mechanical strength. Then, in the laminate film, since the strength of each layer is different, there exists a layer which is removed from another when the force of peeling acts thereon. Furthermore, by selecting synthetic resin for use in the laminate film and using the partial covering film (outer partial covering film) having many layers including a layer of synthetic resin removable at the time of tearing off the strip tape, the peeling occurs within the partial covering film at the time of opening the portion of the pouring opening to make the peeling off of the strip tape very easy and prevent damage such as damage or destruction from being caused to the laminate base material.

In addition, in the portion of the pouring opening where the multilayer partial covering film is attached outside the paper carton, a white colored area formed by a white film may be formed on the partial covering film. at the layer within the interface where peeling occurs within the partial covering film at the time of peeling off the attached strip tape. The above white colored portion can be emulsified by adding white pigment to resin materials such as polypropylene, polyethylene, polyester having heat sealing properties (for example, polyethylene terephthalate). Further, the white colored portion can be formed by providing a printed layer such as white, milky or gray color on the film base. This embodiment is illustrated in Fig. 11, where the partial covering film 11 attached outside is formed of a multilayer laminate film consisting of an adhesive resin layer 11a, a white colored film layer 11e and a synthetic resin layer 11c laminated from the laminate base material 2 side in this order; and at the time of peeling off the strip tape 10, layer peeling occurs in the synthetic resin film layer 11c. Therefore, although the synthetic resin film layer 11c turns white at the time of peeling off the tape, the whitened film layer 11e thereunder is so white that the whitening phenomenon is not visible to the outside at the peeling boundary portion, and when the pouring opening portion is opened, the appearance thereof is not affected. Then, this structure can be applied to the pouring opening portion where the partial covering films are attached from the inside and outside.

As shown in Figures 12 and 13, the pouring opening having the above-mentioned structure can be applied to a paper carton 18 having a cylindrical body.

In this paper board 18, an upper member 18a is obtained from the laminate materials, which is made of extrusion laminate of the low density polyethylene layer of 60 µm thickness on the laminate base material inside and outside on its surfaces. The laminate base material is formed of: a paper board layer (220 g/m²), a polyethylene layer (20 µm thick), a polyethylene layer (15 µm thick), a biaxially oriented polyethylene terephthalate film layer (12 µm thick) and a silicon oxide coated thin film layer (400 Å thick) laminated in this order from the outside of the paper board to the inside of the paper board. To this upper member 18a with the open pore opening, as mentioned above, the partial covering films are attached from the inside and outside. Then, an opening portion 9 is formed therein, and a strip tape 10 is temporarily attached thereto. At the same time, the upper end portion of the body member 18b is wound around the peripheral end of the above upper member 18a and is heat-sealed to provide a flange portion 19 extending upward around the upper member 18a. The lower end portion of the cylindrical body member 18b is wound around the peripheral end of a lower member 18c made of the laminate material and heat-sealed to provide a flange portion 19 extending downward around the lower member 18c. Then, after filling the contents through the opening portion 9 and covering the opening portion 9 with the strip tape 10, the strip tape 10 is heat-sealed to the outer partial covering film, thus producing a paper carton with the sealed pouring opening 1. The inner surface of the carton may be sterilized by using a disinfectant such as hydrogen peroxide before filling the contents therein, and the disinfectant may be removed later to achieve aseptic filling.

The strip band 10 extends beyond the flange portion 19 to provide a convenient take-out portion 20 through the protruding portion located on the surface of the body member 18b beyond the flange portion 19. By using this paper board, it is possible to drink by bringing the mouth to the pouring opening portion while holding it directly with the hand. As mentioned above, the strip band 10 extends beyond the flange portion 19 to cover the portion that the lips touch, thus keeping it clean there until opening. Furthermore, by providing the strip band 10 with the take-out portion 20, the lifting operation of the strip band becomes easy when the pouring opening portion is opened.

In the cylindrical paper carton, the pouring opening is formed so that the open pore opening is covered by the partial covering films from inside and outside. However, another type of pouring opening such as those covering the open pore opening with the outer partial covering film and the inner waterproof film may be applied to this cylindrical paper carton. Then, as shown in Fig. 14, also in the paper carton 18 having a brick-shaped body, the pouring opening 1 mentioned above may be formed on the upper flat surface. Further, as shown in Fig. 15, also in the paper carton 18 having an inclined upper portion, which is called a gable roof, the portion of the pouring opening 1 mentioned above may be formed on the inclined upper surface thereof.

Claims (16)

1. Pouring opening structure (1) of a paper carton, comprising: a laminate base material (2); an outer waterproof layer (6) formed on a surface facing the outside of the paper board made of the laminate base material (2), wherein the laminate base material (2) and the outer waterproof layer (6) are provided with a pouring hole (3) formed therein and extending therethrough; an inner waterproof layer (7) formed on the other surface facing the inside of the paper board made of the laminate base material (2), characterized in that the inner waterproof layer (7) extends over the pouring hole (3) and is provided with an inner waterproof pouring hole (12) formed therein and extending therethrough, the inner waterproof pouring hole (12) being smaller than the pouring hole (3); a partial covering film (11) is attached to the outer waterproof layer (6) along the circumference of the pouring hole (3) such that the partial covering film (11) covers the pouring hole (3) by extending over the pouring hole (3), the partial covering film (11) being provided with a partial covering film pouring hole (13) formed therein and extending therethrough, the partial covering film pouring hole (13) being smaller than the pouring hole (3) and corresponding to the inner waterproof pouring hole (12), the inner waterproof layer (7) and the partial covering film (11) being attached as an attached portion (12a, 13a) to the circumference the inner waterproof pouring hole (12) and the partial covering film pouring hole (13); an opening portion is provided within the pouring hole (3) and is defined by the edge of the attached portion (12a, 13a), the attached portion (12a, 13a) covering the inner peripheral surface (14) defining the pouring hole (3); and a strip tape (10) is removably attached to the partial covering film (11), the opening portion being covered with the strip tape (10). 2. Pouring opening structure of a paper carton comprising: a laminate base material (2); an outer waterproof layer (6) formed on a surface facing the outside of the paper board made of the laminate base material (2), an inner waterproof layer (7) formed on the other surface facing the inside of the paper board made of the laminate base material (2), wherein the outer waterproof layer (6) and the inner waterproof layer (7) are provided with a pouring hole (3) formed therein and extending therethrough; an inner partial covering film (15) attached to the inner waterproof layer (7) along the periphery of the pouring hole (3) such that the inner partial covering film (15) covers the pouring hole (3) by extending over the pouring hole (3), the inner partial covering film (15) being provided with an inner partial covering film pouring hole (16) formed therein and extending therethrough, the inner partial covering film pouring hole (16) being smaller than the pouring hole (3), characterized in that an outer partial covering film (11) is attached to the outer waterproof layer (6) along the periphery of the pouring hole (3) such that the outer partial covering film (11) covers the pouring hole (3) by extending over the pouring hole (3), the outer partial covering film (11) being provided with an outer partial covering film pouring hole (13) formed therein and extending therethrough, the outer partial covering film pouring hole (13) is smaller than the pouring hole (3); the inner partial covering film pouring hole (16) corresponds to the outer waterproof pouring hole (13), the outer and inner partial covering films (11, 15) are attached as an attached portion (13a, 16a) to the periphery of the outer and inner partial covering film pouring holes (13, 16); an opening portion is provided within the pouring hole (3) and is defined by the edge of the attached portion (13a, 16a), the attached portion (13a, 16a) covering the inner peripheral surface defining the pouring hole (3); and a strip tape (10) is removably attached to the outer partial covering film (11), the opening portion being covered by the strip tape (10). 3. A pouring opening structure of a paper carton according to claim 1 or 2, further comprising an annular heat-sealed varnish layer (17) provided on the outer surface of the outer partial covering film (11), wherein the strip tape (10) is removably attached to the partial covering film (11) through the heat-sealed varnish layer (17). 4. A pouring opening structure of a paper carton according to any one of claims 1 to 3, wherein the partial covering film (11) may have a multi-layer structure. 5. A pouring opening structure of a paper carton according to claim 1, wherein the inner waterproof layer (7) extending over the pour hole (3) and the inner partial covering film (15) are formed in a multi-layer structure including a film (15b) having gas barrier properties. 6. A pouring opening structure of a paper carton according to any one of claims 2 to 4, wherein the inner and outer partial cover films (11, 15) are formed in a multi-layered structure including a film (11b, 15b) having gas barrier properties. 7. A pouring opening structure of a paper carton according to any one of claims 4, 5 or 6, wherein the outer partial covering film (11) is formed in a multi-layer structure including a film (11c) having high mechanical strength. 8. A pouring opening structure of a paper carton according to any one of claims 4, 5 or 6, wherein the outer partial covering film (11) is formed in a multi-layered structure including layers which are separated from each other at the time of tearing off the strip tape (10). 9. A pouring opening structure of a paper carton according to any one of claims 1 to 8, wherein the outer partial covering film (11) is formed in a multilayer structure including a white-colored film (11e). 10. A paper carton according to any one of claims 1 to 9, wherein the paper carton has a brick shape with an upper surface and the pouring opening is provided on the upper surface (18a) of the paper carton. 11. A paper carton according to any one of claims 1 to 9, wherein the paper carton has a gable roof shape with an inclined upper surface and the pouring opening is provided in the inclined upper surface of the paper carton. 12. A paper carton according to any one of claims 1 to 91, wherein the paper carton has a cylinder trunk portion with a circular upper surface (18a) and the pouring opening is provided on the circular upper surface of the paper carton. 13. A paper carton according to claim 12, wherein the circular upper surface (18a) has an outer flange portion (19) and the strip band extends outwardly from the pouring opening beyond the outer flange portion (19). 14. Paper carton according to one of claims 10 to 13, wherein the strip band (10) has a removal section (20) at the distal end thereof. 15. A method for producing a pouring opening of a paper carton, comprising the following steps: laminating an outer waterproof layer (6) on a surface facing the outside of the paper board made of a laminate base material (2); forming a pouring hole (3) extending through the laminate base material (2) and the outer waterproof layer (6); laminating an inner waterproof layer (7) on the other surface facing the inside of the paper board of the laminate base material (2) where the pouring hole (3) was formed ; Applying a partial covering film (11) larger than the pouring hole (3) from the exposed portion of the inner waterproof layer (7) through the pouring hole (3) to a flange portion of the outer waterproof layer around the pouring hole (3), whereby the inner peripheral surface defining the pour hole (3) is covered with the inner waterproof layer (7) and the partial covering film (11); forming an opening portion extending through the partial covering film (11) and the inner waterproof layer (7) into the area where the partial covering film (11) is attached to the inner waterproof layer (7); and removably attaching a strip tape (10) to the partial covering film (11) to cover the opening portion with the strip tape (10). 16. A method for producing a pouring opening of a paper carton, comprising the following steps: laminating an outer waterproof layer (6) and an inner waterproof layer (7) on one surface facing the outside of the paper board made of a laminate base material (2) and the other surface facing the inside of the paper board; forming a pouring hole (3) passing through the laminate base material (2), the outer waterproof layer (6) and the inner waterproof layer (7); Placing partial covering films (11, 15) outside and inside with respect to the pouring hole (3), the partial covering films (11, 15) being larger than the pouring hole (3) and being attached to each other in the pouring hole (3), the partial covering films also being attached to the waterproof layers (6, 7) around the pouring hole (3) to cover the inner peripheral surface with the inner and outer partial covering films (11, 15); forming an opening portion extending through the partial covering films (11, 15) into the area where the partial covering films (11, 15) are attached to each other; and removably attaching a strip tape (10) to the partial covering film (11) to cover the opening portion with the strip tape (10).