JPS6128743Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an improvement of a container with a seam covered, and more specifically, a container body having a side seam and a container coated on the inside of the side seam so as to cover the seam. In a container comprising a coating layer, the coating layer is composed of a laminated tape having both surface layers made of a heat-sealable thermoplastic resin and an oxygen barrier intermediate layer, and the laminated tape has both edges attached to the container. The present invention relates to a seam-coated container characterized in that the seam-covered container is in close contact with the inside of the seam while being bent toward the body side. Conventionally, containers made of sheets of paper, plastic film, metal foil, sheets, or a laminate of two or more of these, joined at both edges to form a seam on the side, have been used to store various contents, especially liquids. Widely used as a container for filling inner containers. In a container with this side seam, one edge is exposed into the contents and the other edge is exposed to the outside air. Therefore, there is a problem that corrosion, deterioration, or alteration due to the contents occurs at the inner edge of the side seam. Additionally, in the case of containers consisting of laminated sheets with a paper substrate, the paper substrate from the outer edge of the seam to the inner edge of the seam forms a path for outside air oxygen, thus allowing oxygen to permeate through the seam. leakage will occur at a level that cannot be ignored. The object of the present invention is to provide a joint covering mechanism that effectively prevents gas permeation and leakage at the joint, and also effectively protects the inner edge of the joint from attack by contents. be. The present invention will be described in detail below based on specific examples shown in the accompanying drawings. In FIG. 1 showing the overall arrangement of the paper container of the present invention, this container includes a container body 2 having a seam 1 on the side surface, lids 3a provided at both ends of the container body,
It consists of 3b. In this specific example, the container body 2 includes a paper substrate 4, a metal foil 5,
It consists of a laminated sheet having an inner surface layer 6 made of heat-sealable olefin resin and an outer surface layer 7 also made of heat-sealable olefin resin. Second
In the embodiment shown, the metal foil 5 is attached to the paper substrate 4.
It is arranged so as to be located inside the container, and both are bonded together with an adhesive layer 8 interposed therebetween. Examples of the olefin resins constituting the inner and outer surface layers include low-, medium-, or high-density polyethylene, polypropylene, crystalline ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, ionically crosslinked olefin copolymers, etc. The metal foil used is aluminum foil, tin foil, surface-treated steel foil or iron foil, etc., and the paper substrate is softwood pipe, etc.
Various types of paper such as kraft paper, imitation paper, high-quality paper, coated paper, etc., are used for the pipes made of cypress pipes and other types of pipes. As shown in the enlarged cross-sectional view of FIG.
The olefin resin inner surface layer 6 and the olefin resin outer surface layer 7 are bonded by heat sealing. At this time, a gas passage passing through the paper substrate is formed between the outer cut edge 11 and the inner cut edge 12 of the laminated sheet, which reduces the shelf life of the contents. 12
In the area where the paper substrate 4 is wetted by the contents, various properties of the container are deteriorated, or in the area where the inner edge 12 is corroded by the contents of the metal foil 5, the shelf life of the contents is reduced. For this purpose, a coating layer 13 is provided on the inside of the seam 1, which covers the seam 1. An important feature of the present invention is that the coating layer 13 is composed of a laminated tape having an inner surface layer 14 and an outer surface layer 15 made of heat-sealable thermoplastic resin, and an oxygen barrier intermediate layer 16. The purpose is to bring the laminated tape 13 into close contact with the inside of the seam 1 with both end edges 17 and 18 bent toward the container body side. First, since the oxygen barrier intermediate layer 16 is present in the laminated tape 13, the gas passage formed through the paper substrate 4 is effectively blocked inside the seam 1, and gas permeation and leakage at the seam 1 is effectively prevented. be done. Although the oxygen barrier layer 16 generally exhibits an excellent oxygen barrier effect under low humidity conditions, it is recognized that the excellent action and effect are lost under conditions of contact with the contents. For example, saponified ethylene-vinyl acetate copolymer, which has excellent oxygen barrier properties, has a temperature of 4×10 ^-12 to 6×10 ^-14 cc・cm/cm ²・sec・cmHg at 37°C and 0% RH. However, under high humidity conditions of 100% RH, the oxygen permeability coefficient increases by almost an order of magnitude. Such a tendency is also observed in the case of other oxygen barrier resins, such as nylons. Further, when the oxygen barrier intermediate layer 16 is a metal foil such as aluminum foil, there is a problem that the metal foil corrodes and dissolves into the contents. In the present invention, the oxygen barrier intermediate layer 16
was sandwiched with thermoplastic resins 14 and 15, and since both edges 17 and 18 were bent toward the container body and brought into close contact with seam 1, oxygen barrier layer 16 was affected by humidity and contents. It is possible to completely avoid this and permanently obtain excellent oxygen barrier properties and coating effects. Moreover, since the heat-sealing resin layers 14 and 15 are present on both sides of the oxygen barrier intermediate layer 16, the laminated tape 13 is extremely firmly attached to the inner surface of the container body by heat-sealing in the above-mentioned folded state. It is possible to adhere to or fuse to the surface, making it possible to make the coating more complete. As the heat-sealable resin layers 14 and 15, the aforementioned olefin resin or acid-modified olefin resin is preferably used, while as the oxygen barrier intermediate layer 16, ethylene content of 20 to 60 mol%, A saponified ethylene-vinyl acetate copolymer having a degree of oxidation of 96% or more is most preferably used, but other resins such as nylons and vinylidene chloride resins and metal foils such as aluminum foil may also be used. In order to manufacture the seam-coated container of the present invention, as shown in FIG. When joining by
It is sufficient to supply the material inside the seam 1 in a positional relationship as shown in FIG. The sheet forming the container body is not limited to the laminated sheet shown in Fig. 2, but the present invention has excellent effects on various laminated sheets, especially those where one of the constituent materials is easily affected by the contents. Show effectiveness. In the specific example shown in FIG. 1, lids 3a and 3b separate from the container body 2 are sealingly engaged with the upper and lower ends of the container body 2 by means such as heat sealing. However, in the present invention, the inner layers of the laminated sheets may be overlapped and bonded together by heat sealing at the upper and lower ends of the container body, and each corner may be bent to form a paper container made entirely of laminated sheets. Of course it is possible. The invention will be explained with the following example. Example 1 As a laminated sheet for the container body wall, high-density polyethylene (23μ) / paperboard (270g/m ² ) / low-density polyethylene (20μ) / aluminum foil (12μ) / low-density polyethylene (20μ) / high-density polyethylene (70
μ) was molded using an extrusion lamination method. This sheet was cut into a rectangle of 250 mm x 140 mm to obtain a blank. The blank was placed in a rectangular cylinder with a height of 140 mm and a rectangular horizontal cross-sectional shape with a side length of 60 mm and a radius of curvature of approximately 5 mm at each corner so that the aluminum foil was positioned on the inside of the container relative to the paperboard. to form,
A container body was obtained by high-frequency induction heating and pressure bonding so that the overlap portion (seam) was about 5 to 6 mm. Separately, high-density polyethylene (20μ) / maleic anhydride polyethylene (10μ) / saponified ethylene-vinyl acetate copolymer (12μ: ethylene content 30 mol%) / maleic anhydride were formed using a coextrusion method. Laminated tape (denoted as A) of acid-modified polyethylene (10μ)/high-density polyethylene (20μ) and high-density polyethylene (30μ)/isocyanate adhesive/aluminum foil (12μ)/isocyanate adhesive/high-density polyethylene (30μ) ) was cut into a piece of 15 mm wide and 140 mm long. Next, both ends of the laminated tapes A and B are bent in advance as shown in FIG. Seam correction was performed as shown in the figure (the container body with laminated tape A is designated as AC, and the container body with laminated tape B is designated as BC). On the other hand, as a comparative example, both ends of the laminated tapes A and B were not bent, but were supplied to the seam part of the inner surface of the container body, which had been locally heated with a burner, to correct the seam as shown in Fig. 5. The container body of laminated tape A is NAC, and the container body of laminated tape B is NBC.
). Furthermore, high-density polyethylene (30μ) / maleic anhydride-modified polyethylene containing aluminum hydroxide (15μ) / aluminum foil (100μ) / maleic anhydride-modified polyethylene containing aluminum hydroxide (15μ)
A laminated sheet of μ)/high-density polyethylene (70μ) was molded using an extrusion lamination method. Next, a lid body having the shape shown in FIG. 1 was formed by press molding so that the inside of the container was made of 70 μm high-density polyethylene. This lid is attached to the container bodies AC, BC, NAC and
It was bonded to one end of the NBC using a high-frequency induction heating method (the containers corresponding to the container bodies AC, BC, NAC, and NBC are denoted as K, L, M, and N, respectively). In the thus obtained containers K, L, M, and N having lids at one end, 0.3 wt% glycine, 5.0 wt% glucose, 1.0 wt% citric acid, and vitamin
A glycine-glucose-based browning model solution with 100 mg% C and a pH of 2.8 was fully degassed and the lid was adhered and sealed in the same manner. After sealing, the container should be approximately 1mm thick.
It was covered with a metal holder and sterilized with hot water at 95°C for 5 minutes. The resulting container filled with the glycine-glucose browning model liquid was stored at 30° C. in a dark place, and the residual concentration of vitamin C in the container was measured by indophenol titration after 3 and 6 months. Regarding the container B in which the laminated tape included aluminum foil, the amount of aluminum eluted was measured using flameless atomic absorption spectrometry. The results are shown in Table 1. 【table】

* Undetectable

[Brief explanation of drawings]

Fig. 1 shows the overall arrangement of the container of the present invention, Fig. 2 is an enlarged vertical sectional view of the container body, Fig. 3 is an enlarged horizontal sectional view of the joint, and Fig. 4 shows the arrangement of both end edges. FIG. 5 shows a seam correction diagram cited in the comparative example in the example. 1... Seam, 2... Container body, 3a, 3b...
Lid body, 4... Paper substrate, 5... Aluminum foil, 6, 7...
...Heat sealing resin, 8...Adhesive, 9,10
... Edge of laminated sheet, 11, 12... Cut edge of laminated sheet, 13... Laminated tape, 14, 15...
... Heat-sealing resin, 16 ... Oxygen barrier intermediate layer, 17, 18 ... Laminated tape edge portion.

Claims (1)

[Claims for Utility Model Registration] (1) A container comprising a container body having a side seam and a coating layer applied to the inside of the side seam to cover the seam, the coating layer having heat sealability. It consists of a laminated tape with both surface layers made of thermoplastic resin and an oxygen barrier intermediate layer, and the laminated tape is tightly attached to the inside of the seam with both edges bent toward the container body. A container with a seam covered, characterized by: (2) The container according to claim 1, wherein the container body is formed from a laminated tape having both inner and outer layers made of a paper substrate and a heat-sealable olefin resin. (3) The container according to claim 2, wherein the laminated sheet has a metal foil layer on the inside of the paper-based container. (4) The container according to claim 1, wherein the oxygen barrier intermediate layer comprises a saponified ethylene-vinyl acetate copolymer.