JP2016088608A - Food container and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a food container which satisfies all requirements required for a food container including a gas barrier layer, with good productivity at a low cost.SOLUTION: A food container 10 is integrally molded by sheet molding of a multilayer structure 20 which comprises a PVDC film 22 forming a gas barrier layer, a PET film 26 connected by a dry laminate layer 24 to a container outside surface of the PVDC film 22, a CPP film 30 connected by a dry laminate layer 28 to a container inside surface of the PVDC film 22, and a PPF sheet 32 connected by heat welding to a container inside surface of the CPP film 30.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a food container and a method for producing the same, and more particularly to a food container made of a multilayer resin film sheet including a gas barrier layer and a method for producing the same.

  As a food container for storing retort foods, snacks, etc., an ethylene vinyl alcohol copolymer film that forms a gas barrier layer that has barrier performance against both oxygen and water vapor, and a heat-welded resin layer made of polyethylene, polypropylene, etc. are laminated on the outer surface of the container In addition, a food container having a multilayer structure in which a sealant layer made of polyethylene, polypropylene, or the like is laminated on the inner surface of the film (for example, Patent Document 1), polyolefin resin, polystyrene resin, polyamide resin, polyester resin Or, an easy peel sealant layer made of polyolefin resin or ethylene copolymer is laminated on the inner surface of a multilayer structure made of a resin film such as polycarbonate resin and an ethylene vinyl alcohol copolymer film forming a gas barrier layer. Was Food containers of the layer structure (e.g., Patent Document 2) are known.

  Molding of such a multi-layered food container is performed by heating the multi-layered structure material to a softening point or higher and press-molding with a die after heating.

JP 2014-40284 A JP 2014-84166 A

  The food container with a multilayer structure including a gas barrier layer should not be damaged such that the gas barrier performance is impaired by external factors, has the necessary rigidity as a container to be held, and has good moldability. As required. As for moldability, the film is not cracked (tensile fracture) due to the elongation of the film during molding, and the film does not melt during molding, and molding strips and wrinkles do not occur on the container surface due to poor mold release. Required. Satisfying these two requirements is particularly difficult when the food container has a cup shape and is deep drawn.

  Furthermore, a food container to which a top seal that closes the opening of the container is bonded is required to have an easy peel property when the top seal is peeled off, so that peeling damage does not occur on the top seal bonding surface of the food container. The

  The conventional food containers described above do not have a multilayer structure that satisfies all of these requirements, and in order to satisfy all of the above requirements, a multilayer structure in which many different films and sheets are laminated together has a large number of layers. It becomes a thing. For this reason, in the prior art, the moldability and material economy of the food container are poor, and it is not possible to provide an inexpensive food container suitable as a container for sale such as retort foods and snacks.

  The problem to be solved by the present invention is to provide a high-quality food container including a gas barrier layer at a low cost with good productivity (moldability) by a multilayer structure having the minimum number of laminated layers.

  A food container according to the present invention comprises a polyvinylidene chloride film (22) forming a gas barrier layer, and a polyethylene terephthalate film (26) pressure-bonded to the outer surface of the polyvinylidene chloride film (22) with a dry laminate layer (24). ), A polypropylene film (30) pressure-bonded to the inner surface of the polyvinylidene chloride film (22) by a dry laminate layer (28), and the inner surface of the polypropylene film (30) by heat welding. A multi-layered food container comprising a filler-filled polypropylene sheet (32).

  According to this configuration, the polyvinylidene chloride film (22) is protected by the polyethylene terephthalate film (26), and the necessary rigidity as a container to be held by the filler-containing polypropylene sheet (32) is secured. Since the film in contact with the wall surface on the cavity side of the molding die is a polyethylene terephthalate film (26) having a higher melting point than that of the polypropylene film, the film is brought into contact with the outer surface of the container due to poor mold release due to melting of the film during molding. No forming stripes or wrinkles. The polypropylene sheet (32) containing filler and the polyvinylidene chloride film (22) are pressure-bonded to the vinylidene chloride film (22) by dry lamination, and heat-welded to the polypropylene sheet (32) containing filler. Since the film (30) is interposed, the bonding strength of these films and seals can be increased. As a result, a good food container with a multilayer structure having a high bonding strength including a gas barrier layer can be obtained with good productivity and low cost by the multilayer structure having the minimum required number of layers.

  The food container according to the present invention is preferably bent outward at the container main body (14) having an opening (12) opened upward and the upper edge (16) of the container main body (14). And a flange portion (18) to which the top seal (40) for closing the opening is thermally welded is integrally formed on the upper surface.

  According to this configuration, since the flange portion (18) to which the top seal (40) is heat-welded is formed by the polypropylene sheet (32) containing filler that is thicker and stronger than the polypropylene film (30) or the like, the top seal When peeling (40) from the food container (10), the filler-containing polypropylene sheet (32) is not deformed and peeled off from the polypropylene film (30), and the top seal (40) has an easy peel property. While being able to peel off from the food container 10, peeling damage does not arise in the upper surface of the flange part (18) which is a top seal bonding surface.

  The food container according to the present invention preferably has a thickness of the polyvinylidene chloride film (22) and the polyethylene terephthalate film (26) of 15 μm to 40 μm and a thickness of the polypropylene film (30) of 15 μm to 30 μm. The thickness of the containing polypropylene sheet (32) is 0.25 mm to 1.00 mm.

  According to this configuration, the thickness of the film and the sheet is set to a thickness that is not excessive or insufficient when configuring and molding a good food container including a gas barrier layer, and material economy and moldability are improved.

  The method for producing a food container according to the present invention comprises a polyvinylidene chloride film (22) forming a gas barrier layer, and a polyethylene terephthalate film pressure-bonded to one surface of the polyvinylidene chloride film (22) by a dry laminate layer (24). (26), a polypropylene film (30) pressure-bonded to the other surface of the polyvinylidene chloride film (22) by a dry laminate layer (28), and the polypropylene film (30) are bonded to the polyvinylidene chloride film ( 22) A multilayer structure manufacturing process for manufacturing a multilayer structure (20) comprising a filler-filled polypropylene sheet (32) bonded to the surface on the farther side by thermal welding, and the polyethylene terephthalate film (26) on the outside The multilayer structure (20) And a forming step of forming a vessel shape.

  According to this configuration, a good food container (10) including a gas barrier layer can be manufactured with good productivity and low cost by dry lamination, thermal welding, and hot pressing. Moreover, the filler-containing polypropylene sheet (32) and the polyvinylidene chloride film (22) are pressure-bonded to the vinylidene chloride film (22) by the dry laminate layer (28), and the filler-containing polypropylene sheet (32 ), A heat-welded polypropylene film (30) is interposed, so that the bonding strength of these films and seals can be increased. Further, since the filler-containing polypropylene sheet (32) and the polypropylene film (30) are bonded by heat welding, high bonding strength can be ensured even if the filler-containing polypropylene sheet (32) is thick.

  In the method for manufacturing a food container according to the present invention, preferably, in the multilayer structure manufacturing step, the polyethylene terephthalate film (26) is pressure-bonded to one surface of the polyvinylidene chloride film (22) by a dry laminate layer (24). A first step of manufacturing a laminated body (36) in which the polypropylene film (30) is pressure bonded to the other surface of the polyvinylidene chloride film (22) by a dry laminate layer (28); A second step of joining the filler-containing polypropylene sheet (32) to the polypropylene film (30) of the body (36) by heat welding.

  According to this production method, a first step of producing a laminate (36) of a polyethylene terephthalate film (26), a polyvinylidene chloride film (22) and a polypropylene film (30) by dry lamination, and polypropylene by thermal welding. By the second step of joining the filler-filled polypropylene sheet (32) to the film (30), the multilayer structure (20), which is the material of the food container (10), is manufactured with high bonding strength and high productivity. can do.

  In the method for producing a food container according to the present invention, preferably, the polyvinylidene chloride film (22) has a melting point of 160 ° C. to 165 ° C. and a softening point of 40 ° C. to 55 ° C., and the polyethylene terephthalate film (26) Has a melting point of 260 ° C. to 270 ° C. and a softening point of 75 ° C. to 85 ° C., and the polypropylene (30) has a melting point of 125 ° C. to 135 ° C. and a softening point of 75 ° C. to 85 ° C., The filler-containing polypropylene sheet (32) has a melting point of 150 ° C to 160 ° C and a softening point of 95 ° C to 105 ° C, and the second step is performed by heat welding at 90 ° C to 200 ° C.

  According to this manufacturing method, the food container 10 made of the multilayer structure 20 having high bonding strength can be manufactured with a stable quality without causing thermal damage to the films 22, 26, 30 and the sheet 32.

  In the method for producing a food container according to the present invention, an unstretched film is preferably used as the polypropylene film (30) bonded to the other surface of the polyvinylidene chloride film (22).

  According to this production method, since the polypropylene film (30) is an unstretched film, the food container (10) has sufficient stretchability compared to the case where the polypropylene film (30) is a stretched film. Even if it is a deep drawing shape, a polypropylene film (30) does not produce a tensile fracture at the time of shaping | molding, and the quality food container 10 is manufactured stably.

  According to the food container of the present invention, a good food container including a gas barrier layer can be obtained at a low cost with good productivity by the multilayer structure having the minimum required number of layers. Moreover, according to the manufacturing method of the food container by this invention, the favorable food container containing a gas barrier layer can be manufactured cheaply with sufficient productivity.

The longitudinal cross-sectional view which shows one embodiment of a food container. The expanded sectional view of the II part of FIG. Process drawing which shows the manufacturing process of the multilayered structure used for the food container of this embodiment.

  Hereinafter, one embodiment of a food container according to the present invention will be described with reference to FIGS. 1 and 2.

  The food container 10 is composed of a multilayer structure 20 (see FIG. 2), which will be described later, and as shown in FIG. 1, a container main body 14 having an opening 12 opened upward, and an opening 12. The flange portion 18 bent outward is formed integrally with the upper edge portion 16 that defines the upper edge portion 16 by sheet molding. A top seal 40 that closes the opening 12 is thermally welded to the upper surface of the flange portion 18.

  As shown in FIG. 2, the multilayer structure 20 includes a polyvinylidene chloride (PVDC) film 22 that forms a gas barrier layer, and a polyethylene terephthalate that is pressure-bonded to the outer surface of the PVDC film 22 with a dry laminate layer 24. (PET) film 26, unstretched polypropylene (CPP) film 30 pressure bonded to the inner surface of the PVDC film 22 with a dry laminate layer 28, and bonded to the inner surface of the CPP film 30 by thermal welding It is comprised with the polypropylene (PPF) sheet | seat 32 with a filler.

  PVDC film 22 is preferably exemplified by Saran-UB (registered trademark) manufactured by Asahi Kasei Chemicals Co., Ltd., which has excellent barrier performance against both oxygen and water vapor, and has a thickness of 15 μm to 40 μm and a melting point of 160 ° C. It is a stretched film having a high stretchability (100%) having a softening point of 40 ° C to 55 ° C at 165 ° C.

  The dry laminate layers 24 and 28 formed on both surfaces of the PVDC film 22 are generally made of a polyester-based or polyether-based adhesive layer.

  The PET film 26 is a film that forms the outer surface of the container, and forms a protective layer that prevents the PVDC film 22 from being damaged by an external factor that impairs the gas barrier performance. The PET film 26 is an unstretched film having a thickness of 15 μm to 40 μm, a melting point of 250 ° C. to 270 ° C., a softening point of 75 to 85 ° C., a heat shrinkage of 11.5% in length, and 0.5% in width. .

  Since the PET film 26 is a film that comes into contact with the wall surface on the cavity side of the molding die, heat resistance is required. Polypropylene (PP) has a melting point of 168 ° C. and polystyrene (PS) has a melting point of 100 ° C., whereas PET film 26 has a melting point of about 250 to 270 ° C. and 255 ° C., and PET film 26 is necessary for sheet molding. It has excellent extensibility and heat resistance. Thus, when the sheet is formed, the PET film 26 which is a film that contacts the wall surface on the cavity side is not cracked or melted, and smooth release is performed. Such molding defects do not occur. Since cracks, molding stripes, and wrinkles do not occur on the outer surface of the food container 10, characters and patterns can be printed beautifully on the outer surface of the food container 10.

  The CPP film 30 is an unstretched film having a thickness of 15 μm to 30 μm, a melting point of 125 ° C. to 135 ° C., and a softening point of 75 to 85 ° C.

  The PPF sheet 32 is a sheet made of a composite material in which filler is kneaded using polypropylene as a base material. A suitable filler is talc which is an inorganic powder. The PPF sheet 32 used here contains about 10% by weight of talc, has a thickness of 0.25 mm to 1.00 mm, a melting point of 150 ° C. to 160 ° C., and a softening point of 95 ° C. to 105 ° C. The reinforced resin sheet has a heat shrinkage ratio of 1.4 to 1.6. Since the PPF sheet 32 contains talc, the strength and rigidity (hardness) are increased and the heat resistance is excellent. The rigidity required as a container that the food container 10 has is obtained exclusively by the PPF sheet 32. Since the PPF sheet 32 is a film that comes into contact with the convex wall surface of the molding die, the excellent heat resistance of the PPF sheet 32 also contributes to ensuring the heat resistance required during sheet molding.

  Since the PPF sheet 32 includes a filler, it is difficult to bond with a different film with high bonding strength in the general pressure bonding by dry lamination. On the other hand, in this embodiment, the PPF sheet 32 is joined to the PVDC film 22 via the CPP film 30 that does not include a filler. Since both the CPP film 30 and the PPF sheet 32 are polypropylene and are the same type of film and sheet, the two can be bonded with high bonding strength by thermal welding. Since the CPP film 30 does not contain a filler, the CPP film 30 can be pressure-bonded to the PVDC film 22 with high bonding strength by a general dry laminate layer 28 made of a polyester-based or polyether-based adhesive layer. Thereby, the high quality food container 10 in which the PPF sheet 32 does not peel is stably obtained.

  In addition, the food container 10 has a shearing internal stress at the bonding surface between the film and the sheet due to the difference in thermal shrinkage between the PET film 26 and the PPF sheet 32, so that the strength is higher than when the same material is bonded. As a result, the strength is improved or the thickness is reduced.

  As a result of the above, the PVDC film 22 as the gas barrier layer is not damaged such that the gas barrier performance is impaired by an external factor, has the necessary rigidity as a container to be held, and has good moldability. The food container 10 that satisfies all requirements can be provided with low productivity and low cost by the multilayer structure 20 having the minimum number of layers.

  The thickness of each film 22, 26, 30 and sheet 32 is excessive in constructing and forming a good food container including a gas barrier layer by setting the thickness of each film 22, 26, 30 and sheet 32 described above. There will be no shortage, and material economy and moldability will be improved.

  The top seal 40 is obtained by bonding polypropylene (PP) films 44 and 46 to both surfaces of the gas barrier layer 42 made of an aluminum film or the like by dry lamination or the like. The PP film 44 facing the upper surface of the flange portion 18 is attached to the flange portion 18. Bonded to the top surface. This joining is performed by thermal welding between the PP film 44 and the PPF sheet 32 that forms the upper surface of the flange portion 18.

  Since the top seal 40 is bonded to the PPF sheet 32 which is thicker and stronger than the CPP film 30 or the like, the PPF sheet 32 is deformed and peeled off from the CPP film 30 when the top seal 40 is peeled off from the food container 10. There is no. Accordingly, the top seal 40 can be peeled from the food container 10 with easy peel properties, and peeling damage does not occur on the upper surface of the flange portion 18 that is the top seal bonding surface.

  The food container 10 described above includes a PET film 26 that is pressure-bonded to one surface of the PVDC film 22 by a dry laminate layer, and a CPP film 30 that is pressure-bonded to the other surface of the PVDC film 22 by a dry laminate layer; A multilayer structure manufacturing process for manufacturing the multilayer structure 20 including the PPF sheet 32 bonded to the surface of the CPP film 30 away from the PVDC film 22 by thermal welding, and the multilayer structure It can be manufactured by a molding process (sheet molding process) for molding the body 20 into a container shape.

  According to this manufacturing method, a good food container 10 including a gas barrier layer can be manufactured with good productivity and low cost by dry lamination, thermal welding, and sheet molding. Moreover, between the PPF sheet 32 and the PVDC film 22, there is a CPP film 30 that is pressure bonded to the PVDC film 22 by the dry laminate layer 28 and thermally welded to the PPF sheet 32. The bonding strength of these films and seals can be increased. Moreover, since the joining of the PPF sheet 32 and the CPP film 30 is heat welding, high joining strength can be ensured even if the PPF sheet 32 is thick.

  The PVDC film 22 and the PET film 26 originally have a high elongation rate, and the CPP film 30 is not stretched, and therefore has sufficient stretchability compared to a stretched film. Even if it is a drawn shape, these films do not cause tensile breakage at the time of sheet molding, and a high-quality food container 10 can be manufactured stably.

  As shown in FIG. 3A, the multilayer structure manufacturing process described above includes a material with a dry laminate layer in which dry laminate layers 24 and 28 made of a dried adhesive are laminated on both sides of a PVDC film 22. 3 is prepared, and as shown in FIG. 3 (B), a PET film 26 is pressure-bonded to one surface of the PVDC film 22 by a dry laminate layer 24, and the other surface of the PVDC film 22 is dry-laminated. A first step of manufacturing a laminated body 36 in which the CPP film 30 is pressure-bonded and bonded by the layer 28 and a second step of bonding the PPF sheet 32 to the surface of the CPP film 30 of the laminated body 36 by heat welding are included. The second step can be performed by heat welding at 190 ° C to 200 ° C.

  According to this multilayer structure manufacturing process, the first process of manufacturing the laminate 36 of the PET film 26, the PVDC film 22, and the CPP film 30 by dry lamination, and the multilayer structure 20 that is the material of the thermal melting container 10 are used. Can be manufactured with high productivity as having a high bonding strength.

  Sheet forming includes a step of heating the multilayer structure 20 to a softening point or higher and press-molding the multilayer structure 20 into a container shape with a mold after the heating.

  As a result, a good food container 10 including a gas barrier layer can be manufactured with good productivity and low cost by dry lamination, thermal welding, and sheet molding, and the films 22, 26, 30 and the sheet 32 can be repeatedly heated. Without damaging, the food container 10 made of the multilayer structure 20 having a high bonding strength can be manufactured with a stable quality.

  Although the present invention has been described above with reference to preferred embodiments thereof, the present invention is not limited to such embodiments and can be deviated from the spirit of the present invention, as will be readily understood by those skilled in the art. It is possible to change appropriately within the range not to be. For example, the CPP film 30 interposed between the PVDC film 22 and the PPF sheet 32 can be replaced with a stretched polypropylene film. In addition, all the components shown in the above embodiment are not necessarily essential, and can be appropriately selected without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Food container 12 Opening part 14 Container body part 16 Upper edge part 18 Flange part 20 Multilayer structure 22 Polyvinylidene chloride (PVDC) film 24 Dry laminate layer 26 Polyethylene terephthalate (PET) film 28 Dry laminate layer 30 CPP film 30 Unstretched Polypropylene (CPP) film 32 PPF sheet 32 Filler-filled polypropylene (PPF) sheet 34 Material 36 Laminate 40 Top seal 42 Gas barrier layer 44 Polypropylene (PP) film 46 Polypropylene (PP) film

Claims (7)

A food container,
A polyvinylidene chloride film forming a gas barrier layer;
A polyethylene terephthalate film pressure-bonded to the outer surface of the polyvinylidene chloride film with a dry laminate layer;
A polypropylene film pressure-bonded to the inner surface of the polyvinylidene chloride film by a dry laminate layer; and
A food container having a multilayer structure comprising a filler-filled polypropylene sheet bonded to the inner surface of the polypropylene film by heat welding.   A container body portion having an opening portion opened upward, and a flange portion formed by bending an upper edge portion of the container body portion outwardly and thermally welding a top seal that closes the opening portion on the upper surface And the food container according to claim 1.   The polyvinylidene chloride film and the polyethylene terephthalate film each have a thickness of 15 μm to 40 μm, the polypropylene film has a thickness of 15 μm to 30 μm, and the filler-containing polypropylene sheet has a thickness of 0.25 mm to 1.00 mm. The food container according to claim 1 or 2. A polyvinylidene chloride film that forms a gas barrier layer, a polyethylene terephthalate film that is pressure-bonded to one surface of the polyvinylidene chloride film by a dry laminate layer, and a pressure-bonded bond to the other surface of the polyvinylidene chloride film by a dry laminate layer A multilayer structure production process for producing a multilayer structure comprising a polypropylene film and a filler-filled polypropylene sheet bonded to the surface on the side where the polypropylene film is separated from the polyvinylidene chloride film by thermal welding;
A method for producing a food container, comprising a forming step of forming the multilayer structure into a container shape with the polyethylene terephthalate film as an outside.   In the multilayer structure manufacturing process, the polyethylene terephthalate film is pressure bonded to one side of the polyvinylidene chloride film with a dry laminate layer, and the polypropylene film is pressure bonded to the other side of the polyvinylidene chloride film with a dry laminate layer. A first step of manufacturing the joined laminate (36) and a second step of joining the filler-containing polypropylene sheet (32) to the polypropylene film (30) of the laminate (36) by heat welding. The manufacturing method of the food container of Claim 4 containing.   The polyvinylidene chloride film has a melting point of 160 ° C to 165 ° C and a softening point of 40 ° C to 55 ° C, and the polyethylene terephthalate film has a melting point of 260 ° C to 270 ° C and a softening point of 75 ° C to 85 ° C. The polypropylene has a melting point of 125 to 135 ° C. and a softening point of 75 to 85 ° C., and the filler-containing polypropylene sheet has a melting point of 150 to 160 ° C. and a softening point of 95 to 105 ° C. Yes, The manufacturing method of the food container of Claim 4 or 5 which performs the said 2nd process by heat welding of 190 to 200 degreeC.   The method for producing a food container according to any one of claims 4 to 6, wherein the polypropylene film bonded to the other surface of the polyvinylidene chloride film is an unstretched film.

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