JPS6340467Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a bottom sealing structure for a multilayer tube container with improved resistance to breakage of the innermost layer. In recent years, in order to improve the oil resistance, gas barrier properties, fragrance retention properties, etc. of containers, containers with resins with excellent performance (e.g. nylon resin, saponified ethylene-vinyl acetate copolymer resin, etc.) or metal foil layers have been developed. Multilayer tube containers are widely manufactured and used. The present inventors have developed a container for filling permanent wave agents, which has excellent gas barrier properties, with the inner and outer layers made of polyethylene resin (the inner layer has a thickness of 300μ and the outer layer has a thickness of 100μ), and the middle layer has a nylon resin (thickness of 60μ). A three-layer tube container is manufactured, filled with a permanent wave agent, the end portion is heated, and the entire predetermined width in the axial direction of the tube is pressed simultaneously from both sides to create pressure marks on the outer surfaces of both sides to seal the sealed bottom. After forming and storing them at room temperature for one month, leakage of the contents was observed in all of them. A detailed investigation of this tube container revealed that the contents shown in FIG.
Penetrates from the inner layer 9 at the inner end of the fused portion (sealing portion) corresponding to the position of the side end 11 of the container opening and neck (described later) into the intermediate layer 8, and further penetrates between the inner layer 9 and the intermediate layer 8, It was found that in the resin reservoir 12, the resin penetrated the fused portion between the inner layers 9 or between the inner layer 9 and the intermediate layer 8, destroyed the resin reservoir 12, and leaked to the outside. As a result of further research, the inventors of the present invention found that when a permanent wave agent is filled into a tube container,
Internal pressure will be generated after a certain period of time, the thickness of the innermost layer of the heat-sealed part will be about 1/2 to 2/3 of the sum of both innermost layers before crimping, and it will be similar to multilayer tube containers. In the case of tube containers made of different materials,
The thickness of the innermost layer involved in heat fusion must be thinner than in the case of a single-layer tube container (for reasons of ease of pressing during extrusion, economic efficiency, etc.), etc. This was thought to be the main cause, and after many experiments, the present invention was completed.According to this, leakage does not occur even when filled with a material that generates internal pressure after filling, such as a permanent wave agent. A bottom-sealed structure of a multilayer tube container is obtained. The present invention is a multilayer tube whose innermost layer is made of thermoplastic resin and which has a closed bottom formed by heating the end and simultaneously pressing the entire predetermined width in the axial direction of the tube from both sides to create pressure marks on the outer surfaces of both sides. The container is provided with a thermoplastic resin plate-like member that is interposed between the innermost layers at the location of the above-mentioned press marks, protrudes toward the mouth and neck of the tube container, and is welded to the innermost layer. The present invention relates to a characteristic bottom sealing structure of a multilayer tube container. Next, an embodiment of the present invention will be described. Figures 2A and 2B are perspective views showing the state of the insert and the bottom of the tube container before the insert is inserted into the bottom of the tube, and Figure 3 is a perspective view of the bottom of the tube after the insert has been inserted into the bottom of the tube. crush,
FIG. 4 is an enlarged sectional view showing an example of the process of forming a bottom sealing portion by heating and pressing. FIG. 4 is an enlarged sectional view of the bottom of the tube container that has been heated and pressed. Example First, a three-layer tube body is formed by a three-layer coextrusion method, and the inner layer 9 is made of polyethylene resin (300μ), the middle layer 8 is made of nylon resin (60μ), and the outer layer 7 is made of polyethylene resin (100μ). A shoulder part and a neck part made of polyethylene resin were molded and fixed to one end of the part by injection molding. In this case, if higher gas barrier properties are required, it is preferable to mold the shoulders and mouth and neck in advance with a resin having high gas barrier properties and then fix them. This three-layer tube container is filled with a permanent wave agent, and as shown in FIG. A cylindrical insert 1 made of polyethylene resin (manufactured by Mitsui Petrochemical Co., Ltd.: trademark "ADMER") is inserted into the bottom 4 of the tube container so that the folded piece 3 is in contact with the end of the tube container bottom 4, and then the third As shown in the figure, a slight portion of the crimped portion of the tube container bottom 4 on the side of the container mouth neck was heated while being pressed with a presser metal fitting 5, and crimped with a press mold 6. still,
The width of the crimped portion in the tube axis direction was kept at 1.5 to 2.0 mm. FIG. 4 shows a state in which the insert material 1 and the resin of the inner layer 9 are fused together (in FIGS. 3 and 4, the inner layer, intermediate layer, and outer layer are not drawn separately to simplify the drawings). In this example, the insertion material 1 was made into a cylindrical shape and the folding piece 3 was provided in consideration of workability (easy insertion, prevention of falling off, etc.), but other shapes may be used. You may. What is important here is the length of the insert material 1 made of thermoplastic resin, and by being heated and pressed and welded to the innermost layer of the tube container, the insert material 1
is a thermoplastic resin plate-like member on the entire surface between the innermost layers at the position of the press mark 10, and the end 13 of the thermoplastic resin plate-like member 1a on the tube container mouth and neck side is located at the press mark 10 as shown in FIG. It is located at a position corresponding to the tube neck end 11, or protrudes toward the mouth and neck side of the tube container as shown in FIG. In mass production, due to manufacturing technology, the form shown in Figure 6 will be used, and the above protrusion length will be 2 to 3 mm.
It is preferable to determine the length of the insert 1 so that That is, in mass production, when the sealing bottom is formed by heating and pressing to create pressure marks, the insert material 1 becomes a plate-like member 1a of thermoplastic resin and is placed closer to the mouth and neck of the tube container than the part of the pressure marks. It will stick out. Due to the protrusion of the tube container mouth and neck side, the portions of the press marks 10 on the inner layer corresponding to the tube container mouth and neck side ends 11 are sufficiently covered, and the above-mentioned corresponding portions, which are the boundaries between the pressed portion and the unpressed portion, are covered. Since the parts are reinforced, leakage can be prevented. If the thermoplastic resin plate 1 is
When the container mouth and neck side end 13 of a is located closer to the bottom of the container than the container mouth and neck side end 11 of the press mark 10, the innermost layer corresponding to the container mouth and neck side end 11 of the press mark 10 is exposed. , the permanent wave agent leaks during storage, similar to conventional tube containers. Comparative Example In order to compare with the tube container of the example, three-layer co-extrusion molding was carried out, in which the inner layer, middle layer, and outer layer are respectively made of polyethylene resin (300μ), nylon resin (60μ), and polyethylene resin (100μ), as in the example. A three-layer tube container obtained by fixing the shoulder and mouth and neck to the end of the body obtained in step 1 by injection molding is filled with the same permanent wave agent as in Example, and then the bottom of the tube container is crushed and the inner layer is were fused together by heat and pressure bonding. Leakage Test 1 Ten three-layer tube containers each containing the permanent wave agent shown in the Examples and Comparative Examples were placed in a constant temperature room at 38°C, and after being stored for 12 hours, the condition of each tube container was examined. All 10 tube containers had leakage from the bottom, while the examples had no leakage at all. Leakage Test 2 Ten three-layer tube containers each containing the permanent wave agent shown in the Examples and Comparative Examples were tested at room temperature.
After being stored for several months, the condition of each tube container was examined. In the case of the tube container of the example, there was no change, whereas in the case of the tube container of the comparative example, all of the tube containers were found to have leaked from the bottom. A leak had occurred. The above test results also show that the bottom sealing structure of the multilayer tube container of the present invention has significantly enhanced fusion strength, and the actually obtained breaking strength values of the bottom sealing part are shown below. Bottom sealing part rupture test (1) Inner layer of tube body of test 3-layer tube container: Adhesive polyethylene resin (Mitsui Petrochemical Co., Ltd.)
Made by: Trademark "ADMER") 270μ Intermediate layer: Nylon resin 60μ Outer layer: Adhesive polyethylene resin (Mitsui Petrochemicals Co., Ltd.)
(trademark: "ADMER") 130μ (2) Shape, material, and wall thickness of insert material Cylindrical polyethylene resin as shown in Figure 2.
Wall thickness (in cylindrical shape) is 40μ, 100μ, 240μ, 460μ
Use the one. (3) Test method Cut the tube container vertically so that the width of the bottom sealing part is 2 cm, and peel off the fused part from the container neck side by pinching two parts of the container body (using a presser). The force required for the fused portion to break was measured by pulling the body at two locations (in the opposite direction to the movement of the mold). The results are shown in Table 1.

[Table] This test result also shows that the strength of the bottom sealing part of the tube container of the present invention is significantly enhanced. The combination of the innermost layer (inner layer in the embodiments) resin and insertion material resin of the present invention may be any combination that can be well heat-fused to each other, and when one is made of polyethylene resin, the other is polyethylene resin or ionomer resin. , ethylene-vinyl acetate copolymer, adhesive polyethylene resin (manufactured by Mitsui Petrochemicals Co., Ltd.: trademark "Admer", manufactured by Mitsui Polychemicals Co., Ltd.: trademark "DUMILAN")
), olefin copolymer (Mitsui Petrochemical Co., Ltd.)
(manufactured by Toyobo Co., Ltd.: trademark "Pelprene"), thermoplastic polyester resin (manufactured by Toyobo Co., Ltd.: trademark "Pelprene")
etc., and when one is polypropylene resin, the other is polypropylene resin, adhesive polypropylene resin (manufactured by Mitsui Petrochemical Co., Ltd.: trademark "Admer",
Manufactured by Mitsui Polychemical Co., Ltd.: Trademark "Dyumilan", etc.),
These include ethylene-vinyl acetate copolymer. Table 2 shows examples of suitable combinations of innermost layer resin and insert material resin.

[Table] The resins in Table 2 are merely examples, and resins not shown here can be used as long as they are not thermally decomposed during heat fusion, have dimensional stability, and have good heat fusion properties. The thickness of the insert varies depending on the contents to be filled, but using one that is approximately 40μ (half the thickness, 20μ, for cylindrical inserts, which can be overlapped) or more is effective in improving the strength of the bottom fusion part. As mentioned above, the shape of the insert does not necessarily have to be cylindrical, but it is preferable to make it cylindrical. That is, when the bottom of the tube container is sealed after it is filled with contents, the bottom side of the tube container is heated and pressed while facing upward as shown in Fig. 3, and the end of the tube container body melts and sags slightly downward and outward due to this heating, and therefore the end face of the intermediate layer after pressing is exposed to the outer surface as is clear from Fig. 1 and Figs. 5 to 7, which is undesirable from the viewpoints of corrosion resistance, resistance to contents (resin whose gas barrier property decreases when it absorbs moisture), and aesthetics depending on the nature of the material of the intermediate layer. To avoid this phenomenon, it is preferable to make the folded piece 3 of the insert 1 long so that the folded piece 3 fully covers the end of the tube container body, i.e., the end face of the body and its periphery, and then heat and press the bottom to seal it. In this case, if the insert is cylindrical, the entire circumference of the end of the container body is completely covered with the insert resin, which not only strengthens the strength of the fused part, but also improves the corrosion resistance, resistance to contents, and aesthetics of the container. This device can be applied not only to three-layer tube containers, but also to all multi-layer tubes with two or more layers (including those with a metal foil layer). By using the configuration of this device, the innermost layer corresponding to the neck side end of the container mouth where the impression is made is covered with a plate-shaped member made of thermoplastic resin, so that even if contents that generate internal pressure after filling and sealing, such as permanent wave agents, are filled, they will not leak. In addition, since it is interposed over the entire surface between the innermost layers where the impression is made, the welding strength of the sealed bottom can be maintained.

[Brief explanation of the drawing]

Fig. 1 is an enlarged sectional view of the bottom sealing part of a conventional multilayer tube container in which the bottom fused part has peeled off, and Figs. 2A and 2B are perspective views showing an example of the insert material and the bottom part before being inserted into the bottom part of the tube container. , FIG. 3 is an enlarged sectional view of essential parts showing an example of the process of forming the bottom sealing part of the tube container of the present invention. FIG. 4 is an enlarged cross-sectional view of the main part of the bottom sealing part of the tube container of the present invention. FIG. 5 is an enlarged sectional view of essential parts showing an example of the bottom sealing part of the tube container of the present invention. FIG. 6 is an enlarged sectional view of essential parts showing another example of the bottom sealing part of the tube container of the present invention. FIG. 7 is an enlarged cross-sectional view of the main part of the bottom sealing part of the tube container, which is not included in the present invention. 1: insertion material, 1a: thermoplastic resin plate member,
4: Bottom of tube container, 9: Innermost layer (inner layer), 1
0: Pressure mark, 11: Pressure mark on container mouth neck side edge, 1
3: End of the insert on the neck side of the container mouth.

Claims (1)

[Claims for Utility Model Registration] A sealed bottom whose innermost layer is made of thermoplastic resin and is formed by heating the end and simultaneously pressing the entire prescribed width in the axial direction of the tube from both sides to create pressure marks on the outer surfaces of both sides. In the multilayer tube container, the thermoplastic resin plate member is interposed between the innermost layers at the position of the above-mentioned press marks, protrudes toward the mouth and neck side of the tube container, and is welded to the innermost layer. A bottom-sealed structure of a multilayer tube container characterized by: