JP3823616B2 - Liquid paper container sealing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for sealing a liquid paper container using a paper material, and particularly relates to a method for sealing a liquid paper container including a stretched film in a laminated material constituting the container.
[0002]
[Prior art]
Resin layers are formed on both side surfaces of the paper material constituting the liquid paper container.For example, after filling the content liquid from the opening at the top of the liquid paper container, the opening is sealed when the opening is sealed. Hot air is applied to the seal portion on the entire inner periphery to melt the resin layer of the seal portion, and the seal portions are joined together and pressed to join and seal.
The laminated material constituting such a liquid paper container is, for example, a paper material (basis material 320 g / m ² ) and an outer thermoplastic resin layer (polyethylene (PE 20 μm) formed on the surface of the paper material facing the outside of the paper container. )), An inner first thermoplastic resin layer (PE 25 μm) formed on the surface of the paper material facing the inside of the paper container, a gas barrier layer formed on the inner side of the inner first thermoplastic resin layer, and It is composed of a stretched film (polyethylene terephthalate (PET 12 μm)) formed inside the gas barrier layer and an inner second thermoplastic resin layer (PE 60 μm) formed inside the stretched film.
[0003]
In the laminated material constituting the paper container, a stretched film such as PET is used in order to maintain the strength and rigidity of the paper container and prevent the penetration of the content liquid. On the other hand, when the stretched film is used for the laminated material as described above, the paper container is bent along the folding ruled line, and the folded portion 11 is formed by folding both sides of the opening as shown in FIG. Then, after filling the content liquid from the upper opening, the opening is clamped with a top press to be joined and sealed to obtain a Gobeltop liquid paper container.
[0004]
At this time, the top press is supposed to be cooled by passing cooling water through the inside, but in the step before the top seal, the inner surface of the top seal portion is injected with heated air of about 300 ° C., Since the top press itself is heated by this heated air to be in a heated and melted state, it is no longer in a cooled state, so the top press sandwiches the opening of the paper container and seals, The top seal portion is not cooled and does not become a solidified state, but spreads when a force for returning to the original state is applied.
[0005]
In particular, since the inner second thermoplastic resin layer formed inside the container is still in a molten state after being pressed and joined in a state where the folded portions 11 are folded from both sides, the folded portion 11 is based on the original. There was a risk that a force to return would tend to be peeled off, resulting in a pinhole in the seal portion.
In addition, even in a paper container made of a laminated material containing a stretched film, in the case of a configuration including an aluminum foil (thickness of 7 μm or more), because of the folding retention of the aluminum foil, Since the force that the folding portion tries to return to is reduced, the occurrence of pinholes is suppressed.
[0006]
[Problems to be solved by the invention]
On the other hand, when promoting the recycling of paper containers, if an aluminum foil is present in the laminated material constituting the paper container, it is difficult to recycle, and a paper container made of a laminated material having no aluminum foil is desired. It is rare.
However, when the aluminum foil is removed from the laminated material constituting the paper container, there is a problem in the formability of the paper container, particularly the sealing property of the opening as described above.
[0007]
An object of this invention is to provide the sealing method which does not have a problem in the sealing performance of the said opening part, even if a stretched film exists in the laminated material which comprises a paper container.
Another object of the present invention is to provide a sealing method in which there is no problem in the sealing performance of the opening even if the aluminum foil is not present in the laminated material.
[0008]
[Means for Solving the Problems]
The present invention is a paper material, a resin layer formed on both surfaces of the paper material, and a folded portion on both sides made of a laminated material in which a stretched film is provided between the paper material and a resin layer formed on the inner surface. When a cooling top is blown into the folded portion of the top seal portion after the heated top seal portion is pressure-bonded after filling the contents into a gable top type liquid paper container having This is a method for sealing a liquid paper container, characterized in that cooling air is blown onto the folding portion of the liquid paper container. The invention according to claim 2 is characterized in that cooling air is blown continuously over a predetermined distance (distance) from both sides of the heated and pressure-bonded top seal portion in the conveying direction. The method for sealing a liquid paper container as described in 1. above. According to a third aspect of the invention, the laminated material constituting the paper container, characterized in that it has a configuration that does not include an aluminum foil, a sealing method of a liquid feed container according to claim 1 or 2. The invention according to claim 4 is the liquid paper container sealing method according to any one of claims 1 to 3, wherein the temperature of the cooling air is 20 ° C. or less.
[0010]
[Action]
After filling the contents into a gable top type liquid paper container having folds on both sides and crimping the heated top seal part, the top seal part is immediately cooled to solidify the inner resin layer quickly. Therefore, it can prevent that an opening part returns.
In particular, blowing the cooling air to the folded portion of the top seal portion of the paper container can cool more effectively because the cooling air is held in the folded portion.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a process of filling a liquid paper container with a content liquid and sealing it. A gobel top type liquid paper container 1 having a surface covered with a thermoplastic resin layer and having folds on both sides of an upper part is provided with a feeder part. From A, the paper container sleeve is sequentially raised in a cylindrical shape and sent to the heating step B by the bottom heater. After the bottom is heated, the bottom is folded in the bottom folding step C by the bottom breaker, and the bottom press In the crimping step D, a bottom is first formed.
Next, it is sent to a cleaning process E by a carton cleaner via an unloader, and dust inside the liquid paper container 1 is removed and cleaned, and in the content liquid filling process E, a predetermined content liquid is filled.
[0012]
Then, after filling the content liquid, both sides of the upper part are folded in the upper folding process G by the top breaker, and then the top seal part is heated in the heating process H by the top heater. In the heated liquid paper container, the air in the space of the top seal portion is replaced with an inert gas as necessary, and the top seal portion 1a is sandwiched by the crimping step K by the top press, thereby opening the opening portion. Is sealed.
Next, the sealing method is provided with a cooling step L for cooling the top seal portion 1a after the pressure bonding step by the top press.
The stopper for pouring the content liquid may be attached from the inside or the outside of the paper container before forming the bottom and moving to the washing process for washing the carton via the unloader, or the top seal portion 1a. After cooling, it may be attached from the outside of the paper container.
[0013]
Here, the laminated material used for the liquid paper container of the present invention is mainly made of paper, provided with a thermoplastic resin layer such as PE on the outside, and a first thermoplastic resin such as PE on the inside, stretched A structure in which a second thermoplastic resin layer such as a film or PE is provided, and a structure in which a gas barrier layer is provided between the first thermoplastic resin layer of the laminated material and a stretched film are generally used.
Specific resins for the outer thermoplastic resin layer and the inner first and second thermoplastic resin layers are low density polyethylene (LDPE), linear low density polyethylene (L-LDPE), and metallocene catalyst. Synthesized LDPE, L-LDPE synthesized by metallocene catalyst, or a mixture thereof can be used.
The stretched film may be made of polyethylene terephthalate, polypropylene, or polyamide.
Furthermore, the gas barrier layer can be any of inorganic foil deposited films such as aluminum foil, aluminum deposited film, silicon oxide, aluminum oxide, etc., but from the viewpoint of recycling paper containers, inorganic oxides that are not metals. It is preferable to use a vapor deposition film.
[0014]
As a specific means for cooling the top seal portion 1a after sealing the seal portion of the present invention, as shown in FIG. 2, the top seal portion 1a is transported to the next step while being sealed by a top press. Sometimes, it is carried out by spraying from the cooling air nozzle 20 provided forward in the transport direction toward the folding portion 11 of the paper container. It is sufficient that the temperature of the cooling air sprayed from the air nozzle 20 is 20 ° C. or less.
The cooling air nozzle 20 is effective to inject toward the folding portion 11 on the paper container conveyance direction side, but further injects cooling air toward the opposite folding portion of the paper container. If comprised, both the folding parts will be cooled simultaneously and a sealing state can be maintained reliably.
[0015]
Further, as shown in FIG. 3, in addition to injecting cooling air toward the folding portion of the container as shown in FIG. 2, an ejection hole is formed above the top seal portion 1a of the paper container along the transport direction of the paper container. A large number of pipe-like cooling air pipes 40 may be provided, and cooling air may be jetted from the cooling air pipes 40 toward the top seal portion 1a of the paper container.
The temperature of the cooling air is sufficient if it is 20 ° C. or lower as in FIG.
[0016]
【The invention's effect】
Since the present invention is configured as described above, even if the top press is not cooled by the heated air of the previous step, immediately after the opening is sealed with the paper container with the top press, at least the folding portion, and / or Since the top seal portion is cooled by the cooling air, the melted resin layer is solidified, so that the folded portion is opened against the force of opening the opening, and the generation of pinholes can be prevented.
[0017]
In addition, using a laminated material with a stretched film to prevent the paper container's rigidity, shape retention, and penetration of the contents liquid can prevent the folded portion from spreading after top sealing. A stable paper container can be manufactured.
Furthermore, in addition to the stretched film described above, a laminated material having a structure provided with an inorganic oxide vapor-deposited film can be used to prevent the folded portion from spreading after top sealing, and a stable paper container can be manufactured. it can.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing an example of a filling and sealing method for a liquid paper container.
FIG. 2 is an explanatory diagram showing an example of the cooling method of the present invention.
FIG. 3 is an explanatory view showing an example of the cooling method of the present invention.
FIG. 4 is an explanatory diagram showing a configuration of a cabel top type liquid paper container.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Paper container 1a ... Top seal part 11 ... Folding part 20 ... Air nozzle 40 ... Cooling pipe

Claims (4)

A gable top having folded portions on both sides made of a laminated material in which a paper material, a resin layer formed on both surfaces of the paper material, and a stretched film is provided between the paper material and a resin layer formed on the inner surface After filling the liquid paper container of the mold and crimping the heated top seal part, when blowing cooling air to the fold part of the top seal part, the fold part on the conveyance direction side of the top seal part A method for sealing a liquid paper container, wherein cooling air is blown .   2. The method for sealing a liquid paper container according to claim 1, wherein cooling air is blown continuously over a predetermined distance (distance) from both sides of the heated and pressure-bonded top seal portion in the conveying direction. .   The method for sealing a liquid paper container according to claim 1 or 2, wherein the laminated material constituting the paper container does not contain an aluminum foil.   The method for sealing a liquid paper container according to claim 1, wherein the temperature of the cooling air is 20 ° C. or less.

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