JPH03264338A - Method for pasting cylindrical part of liquid container - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] Regarding a method for bonding the body of a liquid container, more specifically, the body is bonded using a laminated material whose outermost layer is a polyolefin resin layer and whose innermost layer is a polyester resin layer. This invention relates to directionality for providing a bonded body structure with high sealing properties in a container forming a container.

[Prior Art] As a material for the body of a liquid container, a laminated material consisting of a support made of a laminated structure of paper, aluminum, etc., and resin layers on both sides of the support is widely used. For the above laminated materials,
In order to form the body, it is necessary to overlap and bond the edges together. At this time, the cross section of the laminated material that is the inner pair of the bonded part comes into contact with the liquid contents, resulting in contamination of the contents, a decrease in the strength of the laminated material due to liquid penetration into the support such as paper, delamination, and even sealing problems. Oxidation and deterioration of the contents due to defects must be prevented. For this reason, techniques have already been proposed in which the edges of the inner pairs are folded back or a tape is used to surround the same edges.

In addition, for the above-mentioned laminated materials, polyolefin resin with excellent thermal adhesive properties has been used as the resin layer material for many years. There was a problem in that the taste of the contents deteriorated because molecular weight substances migrated into the contents (generally an olefin odor).

For this reason, a technology has been proposed in which the inner layer that comes into contact with the liquid content is made of a laminate made of polyester resin that has a certain degree of thermal adhesiveness and is also highly functional in terms of adsorption and odor. . However, for laminated materials having an outer layer of polyolefin resin and an inner layer of polyester resin, commonly used sealing methods (heat sealing, frame Seals) had the problem that they could not be joined properly in some cases. Table 1 shows the relationship between the sealing method and the combination of resins to be bonded, whether it is acceptable (0) or not (x). In the table, Po indicates polyolefin resin and PET indicates polyester resin.

Table 1 Resin combination Heat seal Frame seal PO/P
OOO PO/PET X 0PET
/PET Ox As described above, in the case of a laminated material consisting of an outer polyolefin resin layer and an inner polyester resin layer, a complex number of factors are involved when bonding the edges together. For this reason, although the laminated structure of the body of a liquid container using this type of laminated material tends to be complicated, there is a problem in that it is difficult to provide good sealing performance. Ta.

Techniques to deal with the above problems include, for example, Japanese Unexamined Patent Publication No. 1-398
36, and JP-A-1-39337. Japanese Patent Application Laid-open No. 1-39338 relates to a technique of using a thermal adhesive for polyester resin.
No. 7 relates to a technique of surrounding the inner pair of edges of a bonded portion with a tape having an inner layer of polyolefin resin and an outer layer of polyester resin.

[Problems to be Solved by the Invention] The technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 1-39337 enables bonding of the tape to the polyester resin layer located on the inner surface side of the inner pair of the bonded portion. I fold the tape over. However, since this folding involves winding the tape further inward, there is a problem in that it is difficult in the manufacturing process. Further, the technique disclosed in the above-mentioned publication uses heat sealing, but heat sealing is slower and less productive than frame sealing, so it is desirable to use frame sealing as much as possible.

The present invention has been made based on this point of view, and an object of the present invention is to provide a method for bonding the body of a liquid container that is easy in terms of process and can obtain good sealing performance by using a tape and using a frame seal. With the goal.

[Means for Solving the Problems] A method according to the present invention which is a distant relative of the above object provides a liquid container in which the body is formed of a laminated material whose outermost layer is a polyolefin resin layer and whose innermost layer is a polyester resin layer. A method for bonding body parts, which includes the steps of folding back the inner pair of the bonded portion to the outside, making the polyester resin layer of the inner pair face outward, and applying a tape having a polyolefin resin layer on the side facing the outer pair. , a step of heat-sealing the tape to the inner pair so that it is interposed between at least the folded polyester resin layer of the inner pair and the outer pair; The method is characterized by comprising a step of frame-sealing the bonded portions of the pair.

[Function] In the method according to the present invention having the above configuration, by disposing a tape having a polyolefin resin layer on the side facing the outer pair in advance on the inner pair, the inner side which is not bonded by the frame seal in an untreated state is The folded polyester resin layer of the pair and the polyester resin layer of the outer pair can be joined by a frame seal.

[Example] Figures 5a and 5b are cross-sectional views showing different examples of laminated materials that can be used in the method for bonding the body of a liquid container according to the present invention.

The laminated material IO shown in FIG. 5a has a structure in which each layer of polyethylene resin 12, aluminum 13, adhesive 14, polyester resin 15, and adhesive 16 are laminated in order on paper 11 as a support, and further, A polyethylene resin layer 17 is formed on the outer surface of the container, and a polyester resin layer 18 is formed on the inner surface.

Further, reference numeral 19 indicates an ink layer printed on the outer surface of the container.

The overall thickness of the laminate 10 is approximately 560 to 640 μm, with the base material portions of layers 11 to 16 having a thickness of approximately 470 to 560 μm, the polyethylene resin layer 17 having a thickness of approximately 25 μm, and the polyester resin layer 1 having a thickness of approximately 25 μm.
8 is approximately 60 μm.

The laminated material 20 shown in FIG. 5b has a structure in which a paper 21 is used as a support, and each layer of polyethylene resin 22, aluminum 23, and polyethylene resin 24 is stacked in order on this. A polyester resin layer 28 is formed on the polyethylene resin layer 27 and the inner surface thereof. Further, reference numeral 29 indicates an ink layer printed on the outer surface of the container. The total thickness of the laminated material 20 is approximately 470 to 560μ
m, and the base material portion of layers 21 to 24 is approximately 410 to 500 μm
One polyethylene resin layer 27 has a thickness of approximately 20 μm, and one polyester resin layer 28 has a thickness of approximately 35 μm.

Suitable polyesters for use in the polyester resin layer 18.28 include crystalline polyesters, non-quality polyesters, low crystalline polyesters, and stretched crystalline (orientated) polyesters, as long as they have low adsorption properties for aroma components, etc. Any type of polyethylene terephthalate, polybutylene terephthalate, acid-modified polyester (DuPont, 5ELORX207, etc.), glycol-modified polyester (Kodak, PET, etc.) may be used.
Polyesters such as G 5116, PETG 6763, etc.) are preferably used.

FIG. 6 is a diagram showing an example of applying the method for bonding the body of a liquid container according to the present invention. A liquid container 30 for a sake pack or a milk bag has a casing or body 32 formed of the above-mentioned laminated material 10 or 20. The method of the present invention is carried out by placing L↓ in such a liquid container, for example, A-A in the figure.
It is applied to bonding between opposite ends of a laminated material after it has been formed into a rectangular shape, as surrounded by a line.

The bonding portion 34 consists of an inner pair 50 and an outer pair 60, and both pairs are joined in a manner described below. FIGS. 1 to 4, which will be explained below, show the bonding part 34 in FIG.
That is, it is an enlarged view of the section taken along the line A--A, and the section taken along the line A--A in FIG. 6 is schematically shown as a whole.

In the method according to the present invention, a corona discharge treatment is performed on the resin layer or tape of the bonded portion as necessary. This treatment mainly modifies the surface of the polyolefin to improve adhesiveness, and can be carried out using, for example, a corona discharge treatment device with an output of 100 kW under conditions of 50% output and a line speed of 100 m/win. The intensity of this treatment can be easily adjusted by changing the power (voltage, current) and line speed.

Also, the tape is attached to the inner pair by heat sealing, but the heat sealing conditions in this case are, for example, 140
°C, 0.5 seconds, ], Okg/cm2.

The inner pair and the outer pair are finally joined by a frame seal. In this case, the actual seal is primarily between the tape and the polyester of the outer pair, and in some embodiments there is a seal in part between the polyolefin of the inner pair and the polyester of the outer pair. The flame conditions are, for example, prepare a frame with a flow rate of 230, 60, 90 (unit: ■・aq), and place the workpiece there at a speed of 120 m/aq.
Pass at 1 rrin and process.

Table 2 shows the relationship between the presence or absence of corona discharge treatment prior to heat sealing and the bonding strength of the bonded portion obtained after heat sealing, for each combination of resins to be bonded. In the table, PE indicates polyethylene resin and PET indicates polyester resin. The unit of bonding strength is kg/15m5 width.

Table 2 111/I! Hil [PE / with PE / without PET
/Yes PET/No PE /Yes 〉5 〉5 Approx. 1.6 Approx. 1.2PE /No 〉5 〉5
Approx. 0 Approx. 0 PET/with Approx. 1.6 Approx. 0 Approx. 3.2 Approx. 2.2 PET/No Approx. 1.2 Approx. 0
Approximately 2.2 Approximately 3.4 The bonding strength by flame sealing is greater than the highest bonding strength by heat sealing, regardless of the presence or absence of corona discharge treatment. However, as shown in Table 1, polyester resins cannot be bonded together using frame seals.

1 to 4 are cross-sectional views showing bonding parts in first to fourth embodiments of the bonding method according to the present invention, respectively. Common parts in the figures are denoted by common reference numerals, and explanations thereof will be omitted. The bonded portion consists of an inner pair 50 and an outer pair 60 near the edge of the laminated material. Both the inner pair 50 and the outer pair 60 have a base material 54.64,
It has polyethylene resin outer layers 5B, H and polyester resin inner layers 58 and 68, respectively.

In the method of the first embodiment shown in FIG. 1, first, as shown by the imaginary line in the figure, the outer polyethylene resin layer 5B of the inner pair 50 of the bonded portion and the center of the base material 54 are A predetermined distance is removed from 52 to form a notch 59. Next, the inner pair 50 is folded back outward at approximately the center of the notch 59, so that the polyester resin layer portion 58a faces outward. The cutout portion 59 is formed by the folded polyester resin layer portion 58a and the inner paired polyethylene resin layer portion 5 adjacent thereto.
The surface of 8a is formed so as to be approximately even.

Next, the tape 70 made entirely of polyethylene resin is
The outer portions 58a and 56a of the inner pair 50 are heat-sealed. At this time, as can be seen from Tables 1 and 2, the inner pair part 58a and the tape part 7'Oa are not joined because they are a combination of polyester resin/polyethylene resin. Therefore, the tape 70 is formed only by joining the portion 70b and the portion 56a of the inner pair.
Supported by 0.

Next, the inner pair 50 and the outer pair 60 are aligned and overlapped, and the frames are sealed.

As a result, the tape portion 70c and the outer pair portion Ha
and are joined. Also, at this time, the tape part 70a which was not bonded by heat sealing and the inner pair part 58a
and are joined.

The method of the second embodiment shown in FIG. 2 uses the same polyethylene resin tape 70 as in the first embodiment, but the joining method is somewhat different from that of the first embodiment. In this embodiment, at least a portion 70a of the tape 70 on the side to be joined to the inner pair 50 is previously subjected to a corona discharge treatment. As a result, the portion 70a of the tape that is not bonded by heat sealing in the first embodiment can be bonded to the inner pair portion 58a. Other points are similar to the first embodiment. In addition, in the above-mentioned corona discharge treatment, it is also possible to treat the region 70b of the tape 70 as necessary or due to operational convenience.

The method of the third embodiment shown in FIG. 3 uses a different tape 80 than the first and second embodiments described above. The tape 80 is
It consists of a coextrusion film or a dry laminated film in which a polyethylene resin layer 86 and a polyester resin layer 88 are laminated with an adhesive resin or adhesive layer 84 sandwiched therebetween. The polyester resin of the tape layer 88 can also be made of the same material as that of the laminate. Also,
The above tape may be coated with metal/foil or gas barrier as required.
It may also contain other layers such as a synthetic resin as an intermediate layer.

In this embodiment, the dimensions of the tape 70 are formed to correspond to one of the folded polyester resin layer portions 58a of the inner pair. Then, the polyester resin layer 88 of the tape
are joined to the inner pair portion 5Ba by heat sealing. Next, when the inner pair 50 and the outer pair 60 are frame-sealed, the polyethylene resin layer 86 of the tape and the polyester resin layer portion 88a of the outer pair are joined. At this time, at the same time, the polyethylene resin layer portion 5 of the inner pair
13b and the outer paired polyester resin layer portion 68b are directly joined. Other points are similar to the first embodiment. In this embodiment, the above-mentioned tape 70
It is also possible to perform the joining prior to folding back the inner pair 50.

The method of the fourth embodiment shown in FIG.
0 is used, but its dimensions and joining method are somewhat similar to the third embodiment. In this embodiment, the tape 80 is attached to the folded polyester resin layer portion 58a of the inner pair 50.
It is formed to have a length extending over the polyethylene resin layer portion 5Ba adjacent thereto.

By subjecting the portion 58a of the inner pair 50 to the corona discharge treatment, both portions 58a and 58a of the inner pair 50 can be bonded to the polyester resin layer 88 of the tape.
Heat seal to 0. Other points are similar to the third embodiment described above. In this embodiment, the corona discharge treatment of the polyethylene resin layer portion 58a of the inner pair 50 can also be performed prior to the folding process of the inner pair 50. Further, when corona discharge treatment is performed after folding, the treatment may also be performed on the portion 58a of the polyester resin layer.

In each of the above embodiments, the notch 59 is formed in the inner pair prior to the folding process so that the surfaces of the folded polyester resin layer portion 58a of the inner pair 50 and the polyethylene resin layer portion 58a adjacent thereto are approximately even. is formed. However, it is also possible to simply fold back the inner pair 50 without providing the notch 59. In addition, in each of the above embodiments,
Although polyethylene resin is used as the material for the outer layer of the laminate and the material for the tape, other polyolefin resins may be used. Further, the tape used in the first and second embodiments is not made of polyolefin resin alone, but may be a double-sided polyolefin tape containing another layer such as metal foil or gas barrier resin as an intermediate layer.

[Effects of the Invention] According to the method of bonding the body of a liquid container according to the present invention, it is possible to obtain good sealing performance by using a frame seal with high work efficiency.

[Brief explanation of drawings]

1 to 4 are cross-sectional views showing bonding parts in first to fourth embodiments of the bonding method according to the present invention, respectively. FIGS. 5a and 5b are cross-sectional views showing different examples of laminated materials that can be used in the method for bonding the body of a liquid container according to the present invention. FIG. 6 is a diagram showing an example of applying the method for bonding the body of a liquid container according to the present invention. 50...Inner pair, 60...Outer pair, 54.84
... Base material, 56, 68 ... Polyethylene resin layer, 5
8.68...Polyester resin layer, 59...Notch, 70.80...Tape, 8B...Polyethylene resin layer, 88...Polyester resin layer Fig. 1 (50

Claims (1)

[Claims] A method for bonding the body of a liquid container in which the body is formed of a laminated material in which the outermost layer is a polyolefin resin layer and the innermost layer is a polyester resin layer, the inner pair of the bonded portion being folded back to the outside, a step of turning the polyester resin layer outward, and interposing a tape having a polyolefin resin layer on the side facing the outer pair at least between the folded polyester resin layer of the inner pair and the outer pair; A method comprising the steps of: heat sealing the inner pair with a tape; and frame-sealing the bonded portions of the inner pair and the outer pair with the tape interposed.