JPH0428534B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method and an apparatus for obtaining a continuous tube by rolling up films having thermoplastic resin layers on at least both the front and back surfaces and sealing the overlapped portions. In more detail, the film is slit to a certain width and is continuously pulled out, rolled into a tube shape, and the overlapped portions on both sides of the film are heated and sealed, especially the envelope pasting method. The purpose is to do this continuously.

Conventionally, continuous sealing of tubes has been carried out on films that have a resin layer that is difficult to melt on the surface and a resin layer that is easy to melt on the inner surface, and is generally heated intermittently with a heating bar and sealed under pressure. Alternatively, the material may be heated and sealed with a knurled roll. However, most of them use the gassho-pasting method, and the envelope-pasting method is not used for continuous sealing.

With the gassho pasting method, the seals are exposed on the outside, which is good when manufacturing simple bags, but when used as the main body of a tube container, for example, the appearance is poor.
In some cases, the product's marketability is significantly lowered, causing the product to lose its value as a high-grade packaging material or container.

Currently, the envelopes that are continuously sealed using the envelope pasting method are, for example, films with a paper layer on the outside and a low-density polyethylene layer on the inside, and the plasticized film on the inside of the edge of the film outside the overlapped part. One method is to heat the low-density polyethylene layer from the outside through the paper layer to plasticize it, and then inject the plasticized resin into the paper layer at the inner edge of the film.

However, the film having the above-mentioned structure has problems in that good surface properties cannot be obtained and the adhesive strength is also very weak. This is because as long as there is a layer on the outside that is difficult to plasticize, such as the paper mentioned above, there will always be a step in the seal area, making it difficult to print or print.
In the case of secondary processing such as varnish coating, there are problems such as the pattern being chipped or the varnish collecting on the steps, making it impossible to form a uniform coating film.Furthermore, since the strength is weak, the seal can be easily damaged by external pressure. This is because if you peel it off from a certain place, something like this will happen.

Therefore, the present inventor has developed a sealing method that can be continuously sealed and has a thermoplastic resin layer on at least both the front and back surfaces, and thereby provides a sealing method that is good in both appearance and strength, and its production. After studying the device, they came to provide the present invention. That is, after rolling up a film made of thermoplastic resin layers on both the front and back sides and heating the overlapping part, the film is wound around a winding mandrel, and the gap between the inner film end and the outer film end of the film overlapping part is heated. By opening the film and blowing heated gas between them, the overlapped part of the film is heated, and while the winding diameter is controlled, the overlapped part is wrapped with the inner roll and the outer roll embedded in the winding mandrel. This is a tube manufacturing method characterized by sealing by applying pressure.

The manufacturing method of the present invention will be explained in detail below using a manufacturing apparatus for specifically implementing it.

FIG. 1 is a front view of the tube manufacturing apparatus of the present invention, in which the film 1 used is supplied by a wound film 2 which is slit to a constant width and has thermoplastic resin layers on at least the front and back surfaces. There is. This rolled film 2 is preferably designed to be tensioned so that when it is placed on the unwinding unit 3 and taken up, it is fed out in a uniform flow. The film 1 supplied from here passes through rollers 4, 4' and enters a sailor 5, where the film is rolled up and wound around a winding mandrel 6 with its front and back turned inside out. Next, the ends of the film 1 are heated by blowing hot air from a torch 7. First, as shown in FIG. 2, in order to regulate the winding direction of the film 1, claws 8 and 8' are provided so as to surround the upper part of the winding mandrel 6. is pressed inward, and the position of the film 1 is regulated so that the film end b, which is the outside of the overlapping part, is outside. In this case, the sailor 5 and the claws 8, 8' for regulating the winding direction may be integrated.

Next, when heating with the torch 7, it is necessary to create a gap so that the inner film end a and the outer film end b do not come into contact until the next pressurizing process. As shown in
A claw 9 that presses inward the non-heated part c of the inner film end a, and a non-heated part d of the outer film end b.
It is necessary to send heated gas from the torch 7 between the ends a and b of the film to keep the ends a and b apart, while pressing the film with a claw 9' that keeps the film in close contact with the winding mandrel 6. Here, if the claw 9' that presses the outer non-heating part film end d is bent upward as shown in the drawing, a part of the hot air sent from the torch 7 will be reflected on the vertical wall 13 of this claw 9, and the hot air will be flee upwards,
Can be heated without heating non-sealed parts.

Furthermore, when the heated film ends a and b come into contact with the winding mandrel 6, the film ends a and b are deprived of heat and the sealing performance is reduced. The vicinity of the passage is defined as a recess 14. In this way, by making it easier for both ends a and b of the film to separate inward and outward,
Areas that do not require fusing are cooled by contact with the wrapping mandrel, and even if some heated gas flows to non-heated areas, local heating is possible only near the edges where heating is sealed. Therefore, even if the temperature at the film ends a and b is sufficiently high, the effect on other parts can be reduced.
Furthermore, since the film has firmness, wrinkles are difficult to form, and since only the heated film ends a, b are reduced in firmness, the winding diameter of the tube is stabilized. Therefore, it is preferable to keep the winding mandrel 6 cool.

Next, the pressure sealing process is as shown in Figure 4.
In order to prevent the film from loosening, the winding diameter is controlled by claws 12 and 12' protruding from both sides.
Two pressure rolls 10 and 11 provided inside and inside
Seal under pressure. Here, the inner pressure roll 10
Since it is difficult to cool down, it is preferable to use a material that is heat resistant and has good slipperiness at high temperatures. On the other hand, the outer pressure roll 11 has a structure that allows it to be cooled, so that the heated film ends a and b are overlapped, pressed and fused together, and can be cooled sufficiently at the same time.
The tube sealed in this way is taken off to the left in the drawing by a take-off machine (not shown), so that the film can be sealed continuously.

As described above, in the manufacturing apparatus according to the present invention, from the process of heating the film end to the sealing process, the claws 8, 8' for regulating the winding direction and the non-heated part c of the inner film end a are used. a claw 9 that presses the film inward, a claw 9' that brings the non-heated part d of the outer film end b into close contact with the winding mandrel 6, and a claw 9' that controls the winding diameter when sealing the overlapped part of the film.
At least six types of nails 12, 12' are used to tightly attach the film to the winding mandrel 6 from both sides.
This is a tube manufacturing device that uses tubes one by one.

The present invention provides a manufacturing method and a manufacturing apparatus as described above, and includes, for example, a method for obtaining a tube from a film whose front and back surfaces are made of thermoplastic resin such as polyethylene, by bringing a heating bar into contact with the film as conventionally used. In the heating method, when a thermoplastic resin such as polyethylene is heated and melted, the film and heating bar stick together, and unless it is cooled sufficiently, the film and heating bar will not separate, resulting in a lack of stability and a slow molding speed. I have no choice but to be late. Furthermore, the method of contacting and sealing heated rolls is also quite impractical. In addition, as seen in Japanese Patent Application Laid-open No. 54-7477, when pressure is applied using a winding mandrel (forming plate) with no moving parts and a rotating roll that synchronizes with the movement of the film, the film on the inside (mandrel side) moves. Because the speed is lower than the movement speed on the outside (roll side),
Smooth movement of the film cannot be expected, resulting in wrinkles in the film and variations in the diameter of the product tube. However, in the present invention, the inner roll and outer roll embedded in the winding mandrel are used to move the film. Since the overlapped parts are sealed by applying pressure, there is no difference in speed between the inside and outside, so the tube has a sealed tube with excellent appearance and excellent strength, with less wrinkles and fluctuations in tube diameter. can be manufactured efficiently. In addition, since molding can be performed at a uniform speed, it is easy to coat the film-wound tube with resin in-line, and to obtain a long tube, which is an advantage of the manufacturing method according to the present invention. is big. Further, the device according to the present invention requires only low accuracy of the sailor and other parts can be easily manufactured, so the device cost is very low and the winding diameter can be easily changed. In addition, in the process of heating the film edge, the inner film edge is held in a recess provided in the winding mandrel, and a claw is used to release the film edge to regulate the film edge to be on the outside of the overlapping part. Therefore, when applying hot air, the end of the film does not come into contact with the cold winding mandrel, so there is no deterioration in sealing performance due to heat being taken away by the winding mandrel. Furthermore, in the process of sealing the overlapping portion of the film by applying pressure using the inner roll and outer roll embedded in the winding mandrel, wrinkles may occur because the winding diameter regulating claw is used to regulate film slack. It is possible to efficiently manufacture sealed tubes with good appearance and excellent strength, with reduced variation in tube diameter. Furthermore, the manufacturing method and apparatus are also suitable for manufacturing tubes currently used for the main body of toothpaste tube containers, etc., which include aluminum foil, paper, etc., and have thermoplastic resin on the inside and outside surfaces.

[Brief explanation of drawings]

The drawings show one embodiment of the device of the present invention, and FIG. 1 is a front explanatory view of the device of the present invention, and FIG.
Figures 3 and 4 are cross sections A-A and B-
FIG. 3 is a sectional view showing a B cross section and a CC cross section. 1... Film, 2... Roll film, 3... Unwinding unit, 4... Roll, 5... Sailor, 6
... Winding mandrel, 7 ... Torch, 8 ... Claw for regulating the winding direction, 9, 9' ... Claw for separating the film end, 10 ... Inner roll, 11 ... Outer roll, 12 ... ... Winding diameter regulating claw, 13... Vertical wall,
a: inner film end, b: outer film end, c, d: non-heated part.

Claims (1)

[Claims] 1. Rolling up films each having thermoplastic resin layers on both the front and back surfaces and heating the overlapped portions,
The film is wound around a winding mandrel, the inner film end portion and the outer film end portion of the film overlap portion are opened, and heated gas is blown between them to heat the film overlap portion. , and a method for manufacturing a tube, characterized in that the overlapping portion is sealed by applying pressure with an inner roll and an outer roll embedded in a winding mandrel while regulating the winding diameter. 2 From the step of rolling a film whose front and back surfaces are made of thermoplastic resin layers, the step of heating the ends of the film, and the step of sealing the overlapping portion of the film by applying pressure using an inner roll and an outer roll embedded in a winding mandrel. In this tube manufacturing device, in the process of rolling the film, the winding direction is controlled so that the end of the film that is inside the overlapped portion is held against a winding mandrel, and the end of the film that is outside the overlapped portion is on the outside. In the process of heating the film end, the film end part is used to hold the inner film end in a recess provided in the winding mandrel and to regulate the film end to be outside the overlapped part. a claw to release the
A tube characterized in that it is provided with a winding diameter regulating pawl for regulating film slack in the step of sealing the overlapping portion of the film by applying pressure using an inner roll and an outer roll embedded in a winding mandrel. manufacturing equipment.