Composite container and method for manufacturing composite container

Abstract

This composite container comprises: a paper container formed by bonding a trunk member and a bottom sheet member; and a resin film affixed to the inner surface of the paper container. In the paper container, paper is exposed at a surface where the paper container and the film are adhered. In the paper container, a side bonding part for bonding the side surface of the trunk member and a bottom bonding part for bonding the trunk member and the bottom sheet member are each bonded by means of a bonding agent. The film includes an adhesive layer for adhering to the paper of the paper container.

Description

Composite container and method of manufacturing the composite container

[0001] The present invention relates to a composite container in which a film is attached to the inner surface of a paper container, and a method for manufacturing the composite container.

[0002] In some composite containers, the inner surface of the container is coated with resin to prevent leakage of the contents from the joints of the containers (see, for example, Patent Document 1). The container in Patent Document 1 has a preformed resin inner container fitted into a paper outer container, and the opening edges of the inner container and the outer container are rolled outward together to form a curled portion. In other words, the inner and outer containers are joined by forming a double curled portion. The container in Patent Document 1 has problems such as a larger amount of resin than a paper container alone, and a space being created between the outer and inner containers, reducing the internal volume of the container.

[0003] In addition, there is a method for manufacturing a composite container in which a preform having a shape corresponding to the opening of the container is injection molded in advance, and the preform is stretched by pressure forming or vacuum forming to be combined with the inside of the container (see, for example, Patent Document 2). In the manufacturing method in Patent Document 2, a heated resin preform is pressure formed or the like to combine the resin material with the inner surface of the container, but there is no description about the adhesiveness between the resin and paper.

[0004] Furthermore, in a method for manufacturing a composite container, a lining film is adhered to the inside of a paper outer cup by vacuum suction, and the inner surface of the outer cup is covered with an inner cup (see, for example, Patent Document 3). In the manufacturing method of Patent Document 3, a bottom plate member of the container is intermittently joined to the lower part of a container body member, and vacuum suction is performed through the non-jointed parts between the bottom plate member and the container body member to adhere the lining film to the entire inner surface of the container. In the manufacturing method of Patent Document 3, a plug is lowered while in contact with the lining film to assist the vacuum suction, thereby stretching the lining film, but it is necessary to adjust the descent speed of the plug, the degree of contact between the plug and the lining film, etc.

[0005] Japanese Patent Application Laid-Open No. 2001-180641 Japanese Patent Application Laid-Open No. 3-176128 Japanese Patent Application Laid-Open No. 2004-224422

[0006] The present invention has been made in view of the above-mentioned background art, and has an object to provide a composite container in which a resin film provided on the inner surface is stably adhered, and a method for manufacturing the composite container.

[0007] According to one embodiment, the composite container comprises a paper container formed by joining a body member and a bottom plate member, and a resin film attached to the inner surface of the paper container, in which the base paper of the paper container is exposed at the adhesive surface between the paper container and the film, and in the paper container, the side joints that join the sides of the body member and the bottom joint that joins the body member and the bottom plate member are each joined via an adhesive, and the film has an adhesive layer that adheres to the base paper of the paper container.

[0008] According to one embodiment, the method for manufacturing a composite container is a method for manufacturing a composite container comprising a paper container formed by joining a body member and a bottom plate member, and a resin film attached to the inner surface of the paper container, in which the base paper of the paper container is exposed at the adhesive surface between the paper container and the film, and the film has an adhesive layer that adheres to the base paper of the paper container, and the method comprises an adhesive application process for applying adhesive to portions of the inner surface of the paper container that correspond to side joints that join the sides of the body member and the bottom joint that joins the body member and the bottom plate member, a joining process for joining the side joints and the bottom joints, respectively, and a film attachment process for attaching the film to the adhesive surface of the paper container by using an air pressure difference.

[0009] FIG. 1A is a conceptual cross-sectional view illustrating a composite container, FIG. 1B is a developed view illustrating the body member of the composite container, and FIG. 1C is a partially enlarged cross-sectional view of the composite container. FIGS. 2A and 2B are enlarged cross-sectional views of the area around the bottom joint of the composite container. FIG. 3 is a conceptual view illustrating the feeding of a body member blank. FIG. 4A is a diagram illustrating the thickness of a film attached to a paper container, and FIG. 4B is a table illustrating examples of film thickness. FIG. 5 is a conceptual cross-sectional view illustrating a film attachment device used in the film attachment process. FIG. 6 is a flowchart illustrating a paper container manufacturing method. FIGS. 7A to 7C are conceptual diagrams illustrating a paper container manufacturing method. FIGS. 8A and 8B are tables illustrating examples of composite containers. FIGS. 9A to 9D are developed views illustrating the application locations of adhesive agent on the body member for an example of a composite container. FIGS. 10A to 10C are diagrams illustrating modified side application portions of adhesive agent at the side joints. FIGS. 11A to 11E are diagrams illustrating modified bottom application portions of adhesive agent at the bottom joints. Figures 12A and 12B are diagrams illustrating modified examples of the adhesive application portion at the bottom joint. Figure 13 is a conceptual diagram illustrating a modified example of a composite container. Figures 14A to 14C are enlarged cross-sectional views illustrating the mouth of a modified composite container. Figure 15 is an enlarged cross-sectional view of the periphery of the bottom joint of a modified composite container.

[0010] [Embodiment] Hereinafter, a container and a method for manufacturing a container according to the present invention will be described with reference to the drawings.

[0011] Fig. 1A is a cross-sectional view showing an example of a composite container 10. Fig. 1B is a development view of a body member 11, described later, of the composite container 10 shown in Fig. 1A. In Fig. 1B, the portion to which a bonding agent HS, described later, is applied is shown by a matte-finish filled pattern. Fig. 1C is an enlarged view of the portion of the composite container 10 shown in Fig. 1A surrounded by a dotted line MA.

[0012] 1A, the composite container 10 is a cup-shaped container in which a resin film FL is attached to the entire inner surface IS of a paper container PC. The composite container 10 has a mouth portion PCa, which is a circular opening at the top, and the side surface of the composite container 10 is tapered in the vertical direction. The composite container 10 has a curled portion PCb formed by rolling the peripheral edge of the opening outward.

[0013] The paper container PC is formed by joining a body member 11 and a bottom plate member 12. The bottom P3 of the paper container PC is closed by the bottom plate member 12. The outer periphery 12c of the bottom plate member 12 has a peripheral wall portion 12b bent downward. The peripheral wall portion 12b is joined to the bottom portion 11b of the body member 11. As shown in enlarged views in Figures 2A and 2B, the bottom portion 11b of the body member 11 is bent inward at its lower end, and the peripheral wall portion 12b is sandwiched between the outer wall portion 11ba and inner wall portion 11bb of the body member 11.

[0014] In the paper container PC, the side joint portion 13a and the bottom joint portion 13b shown in FIG. 1B are joined together via a bonding agent HS. The side joint portion 13a is a portion that joins the side surface of the body member 11 (hereinafter also referred to as the side SD). Here, the portion that joins the side surface of the body member 11 refers to the end portions 3a and 3b of the side surface of the body member 11, and the body member 11 is formed into a cylindrical shape by bonding the end portions 3a and 3b together so that they overlap each other. The side SD corresponds to the inner surface IS of one of the end portions 3a and 3b of the side surface of the body member 11. The bonding agent HS is applied to the entire surface of the side SD, i.e., the inner surface IS of one of the end portions 3a, as a side application portion SS.

[0015] The bottom joint portion 13b is a portion (hereinafter also referred to as bottom BT) that joins the body member 11 and the bottom plate member 12. In the body member 11, the portion that joins the body member 11 and the bottom plate member 12 is the area of ​​the inner surface IS of the lower end portion 3c of the body member 11, excluding the side end portion 3a (side SD). The adhesive HS is applied to a portion of the bottom BT as a bottom application portion CC. Specifically, the bottom application portions CC are arranged in multiple locations at regular intervals or intervals. Each bottom application portion CC has, for example, a rectangular shape and a uniform width or area. The area of ​​the bottom BT other than the bottom application portions CC is a bottom non-application portion NC1, which corresponds to the non-bonded portion NB described below. The bottom application portion CC has multiple elongated regions. Each region is arranged approximately parallel to the longitudinal direction of the paper container PC. The bottom coating sections CC are arranged in a slightly radial pattern along the lower end 3c when viewed in the developed view of FIG. 1B.

[0016] The bottom coating area of ​​the bottom BT, where the bonding agent HS is applied, is in the range of 26% to 80% of the total area of ​​the bottom BT. The bottom coating area is the area of ​​the bottom BT excluding the bottom non-coated portion NC1, and is the total area of ​​the multiple bottom coated portions CC. The number of bottom coated portions CC is, for example, 20.

[0017] As shown in Figures 2A and 2B, the bottom joint portion 13b has a portion with the adhesive HS and a portion without the adhesive HS (non-bonded portion NB). A portion of the bottom joint portion 13b has a ventilation portion AP that allows ventilation to the outside of the paper container PC due to the non-bonded portion NB shown in Figure 2B. That is, the ventilation portion AP is formed by the bottom non-coated portion NC1 where the adhesive HS is not applied. The non-bonded portion NB forms a small gap between the bottom portion 11b of the body member 11 and the peripheral wall portion 12b of the bottom plate member 12, and this gap becomes the ventilation portion AP. The ventilation portion AP allows ventilation to the outside of the paper container PC by vacuuming when attaching the film FL to the inner surface IS of the paper container PC. This improves ventilation during vacuuming, improving the formability of the film FL.

[0018] The adhesive HS is also applied to a strip-shaped portion (hereinafter also referred to as a top TP) corresponding to the curled portion PCb of the paper container PC. The top TP corresponds to the inner surface IS of the upper portion 3d of the body member 11. The adhesive HS is applied to the entire top TP. The curled portion PCb curls around the adhesive HS applied to the inner surface IS of the paper container PC.

[0019] As described above, the adhesive HS is applied to the sides SD, bottom BT, and top TP of the blank of the body member 11 to maintain the cup shape of the paper container PC. When applying the adhesive HS to the sides SD and bottom BT, the adhesive HS can also be applied to the top TP. This reduces the number of processes. Furthermore, by partially applying the adhesive HS to the inner surface IS of the paper container PC, the amount of resin used to bond the components of the paper container PC to each other can be reduced, making it more environmentally friendly. Furthermore, the surface of the inner surface IS of the paper container PC that comes into direct contact with the film FL, i.e., the adhesive surface BS, can be made of base paper 14. The surface of the base paper 14 alone has better adhesion to the adhesive layer 16 of the film FL (described below) than a surface of the base paper 14 that has been generally laminated, resulting in stable adhesion between the paper container PC and the film FL.

[0020] The adhesive HS applied to the top TP prevents the lubricant used in processing the curled portion PCb from penetrating into the base paper 14 of the paper container PC. This prevents the curled portion PCb from curling up. If the lubricant penetrates into the base paper 14, the base paper 14 loses its rigidity, making it difficult to curl, resulting in a container in which the curled portion PCb cannot be completely wound or is buckled. Furthermore, when the curled portion PCb is pressed with a hot plate (not shown), the adhesive HS applied to the top TP, which corresponds to the curled portion PCb, prevents the curled portion PCb from unwinding. Furthermore, applying the adhesive HS to the top TP allows the blanks of the body member 11 to be fed one by one during the molding of the paper container PC. As shown in FIG. 3 , the blanks are fed into the molding device using a holding device (not shown) with a slit ST. During this process, the blanks can be fed one by one by vacuum suction through the slit ST. If the paper overlapping the slit ST is air permeable, two blanks may be sucked in. Applying adhesive HS to the top TP makes the coated area less permeable, preventing the two blanks from being sucked in. However, if the top TP is made of a material that is less permeable, it is not necessary to apply adhesive HS.

[0021] The adhesive HS is applied to the blank of the body member 11 before molding the paper container PC. The adhesive HS is applied by, for example, printing. The amount of adhesive HS applied is, for example, 5 g / m ２ ~20g / m ２ is.

[0022] Examples of the bonding agent HS include a heat sealing agent, an adhesive for bonding by pressure, etc. The types of bonding agent HS applied to the sides SD, the bottom BT, and the top TP may be different.

[0023] The heat-sealing agent is, for example, a thermoplastic resin. Examples of thermoplastic resins include polyethylene and modified resins thereof, ionomer resins, ethylene-methacrylic acid copolymer resins, ethylene-acrylic acid copolymer resins, ethylene-vinyl acetate copolymer resins, styrene-acrylic acid copolymer resins, cellulose acetate resins, polyester resins, polylactic acid resins, polyhydroxyalkanoic acid resins, polybutylene succinate resins, polybutylene succinate adipate resins, hydroxybutyrate-hydroxyhexanoate copolymer resins, polyvinyl alcohol resins, ethylene-vinyl alcohol copolymer resins, polypropylene and modified resins thereof, polyhydroxybutyric acid resins, acrylic acid resins, methacrylic acid resins, polyethylene terephthalate resins, and polyamide resins. The heat-sealing agent is a material obtained by dispersing, dissolving, or emulsifying a thermoplastic resin in water or a solvent.

[0024] Examples of adhesives that can be used for bonding by pressure bonding include modified vinyl acetate resin, vinyl acetate resin, acrylic-modified vinyl acetate copolymer resin, vinyl copolymer resin, ethylene-vinyl acetate copolymer resin, urea resin, melamine resin, phenolic resin, resorcinol resin, chloroprene rubber, epoxy resin, urethane resin, silicone resin, modified silicone resin, styrene-butadiene rubber copolymer resin, isobutene-maleic anhydride copolymer resin, vinyl chloride resin, starch, nitrile rubber, rosin, acrylic acid resin, methacrylic acid resin, acrylic acid ester resin, and methacrylic acid ester resin.

[0025] As shown in Fig. 1C, the paper container PC has base paper 14. The base paper 14 used for the body member 11 has a basis weight of, for example, 150 to 400 g / m ２ The base paper 14 used for the bottom plate member 12 has a basis weight of, for example, 150 to 400 g / m ２ The basis weight is 150 g / m ２ If the weight is less than 400 g / m, the container will not have enough rigidity and will not be able to stand on its own. ２ If there is more, the hair will be too stiff and you won't be able to create a top curl.

[0026] In the composite container 10, the base paper 14 of the paper container PC is exposed at the adhesive surface BS between the paper container PC and the film FL. A printed layer 15 that decorates the composite container 10 is formed on the outer surface OS of the base paper 14. The printed layer 15 displays information such as pictures and letters, as well as marks described below, by printing on the outer surface OS of the composite container 10. For example, OP varnish (overprint varnish), heat sealing agent, lamination, etc. are used as the printed layer 15. This makes it possible to waterproof the composite container 10. The printed layer 15 may be a combination of ink and OP varnish, ink and heat sealing agent, or ink and lamination. These combinations provide the above-mentioned waterproof effect and prevent ink bleeding.

[0027] The printed layer 15 includes marks on the outer surface OS of the base paper 14 for applying the adhesive HS to predetermined locations on the inner surface IS of the base paper 14. The adhesive HS is applied using these marks as a reference. Furthermore, when cutting out blanks for the body member 11, the marks on the printed layer 15 are also used as a reference when cutting out the blanks so that they match the position of the adhesive HS on the inner surface IS of the base paper 14. Note that if the function of the marks can be replaced by another method, the printed layer 15 may be omitted.

[0028] The film FL is attached to the adhesive surface BS, which is the inner surface IS of the base paper 14 of the paper container PC. For the film FL to stably adhere to the paper container PC, as described above, the film FL needs to contact the exposed portion of the base paper 14. The thickness of the film FL varies depending on the adhesion position with the paper container PC, with the film FL adhered to the bottom P3 (see FIG. 1A) of the paper container PC being thicker than the film FL adhered to the inner wall P2 (see FIG. 1A) of the body portion. The thick film FL at the bottom P3 prevents pinholes from forming in the film FL when the composite container 10 is filled with sharp contents or when the composite container 10 is dropped. The thick film FL at the bottom P3 makes it less likely for the film to shrink due to heat generated by the contents during microwave heating, preventing peeling between the paper container PC and the film FL. The thick film FL at the bottom P3 brings the center of gravity of the composite container 10 closer to the bottom P3, making the composite container 10 less likely to tip over. The thickness of the film FL changes depending on the adhesion position if the inner diameter of the mouth portion PCa of the paper container PC and the height of the paper container PC change.

[0029] FIG. 4A is a diagram illustrating the thickness of the film FL attached to the paper container PC. FIG. 4B is a table illustrating specific examples of the thickness of the film FL. The thickness of the film FL before attachment was 100 μm. Thickness measurements were performed using a micrometer or a thickness gauge. Measurement locations were four points on the circumference of the body center E1 of the film FL, four points on the circumference of the V zone E2, and one point at the bottom center E3. Five samples were taken, and the measurements shown in FIG. 4 are average values. For the measurements at the body center E1 and the V zone E2, the four points at the body center E1 and the four points at the V zone E2 were averaged for each sample, and the average values ​​for the five samples were further averaged. For the measurement at the bottom center E3, the one point at the bottom center E3 was averaged for the five samples. The V zone E2 corresponds to the V zone VZ shown in FIGS. 2A and 2B. The V zone VZ is the portion where the body member 11 and the bottom plate member 12 are connected.

[0030] 1C, the film FL has a three-layer structure. Specifically, the film FL has, in order from the adhesive surface BS side of the base paper 14, an adhesive layer 16, an intermediate layer 17, and a substrate layer 18 that supports the adhesive layer 16 and the intermediate layer 17.

[0031] The base material layer 18 is provided on the innermost side of the composite container 10 and is the layer that comes into contact with the contents of the composite container 10. The base material layer 18 has water resistance, chemical resistance, etc. The base material layer 18 can be made of, for example, polypropylene (PP) or polyethylene (PE).

[0032] The intermediate layer 17 is a layer that mainly suppresses the formation of pinholes. Examples of the intermediate layer 17 that can be used include a laminate of Ny (nylon) and EVOH (ethylene vinyl alcohol resin), or a laminate of ionomer and EVOH. Ny and ionomer have elasticity and flexibility, and function to prevent pinholes in the film FL. EVOH has gas barrier properties and oil resistance, and functions as a barrier material. By providing the intermediate layer 17, the film FL can be made thinner.

[0033] The adhesive layer 16 is a layer that adheres to the base paper 14 of the paper container PC. As shown in FIG. 1A , the adhesive layer 16 adheres to all surfaces of the mouth portion PCa or flange P1, the body inner wall P2, and the bottom P3 of the paper container PC. However, the adhesive layer 16 does not adhere to the V zone VZ. The adhesive strength of the adhesive layer 16 is such that when the film FL is peeled from the base paper 14, the paper fibers adhere to the film FL. Specifically, the adhesive strength of the adhesive layer 16 ranges from 0.5 N / mm to interlayer delamination of the paper. The measurement width for adhesive strength is 15 mm.

[0034] Examples of the adhesive layer 16 include polyolefins such as polypropylene and polyethylene, modified resins thereof, polyester resins such as polyvinyl chloride and polyethylene terephthalate, thermoplastic resins such as ethylene-vinyl acetate copolymer resin (EVA), ethylene-vinyl alcohol copolymer resin, polyamide resin, polyvinylidene chloride resin, polystyrene resin, polycarbonate resin, polybutene resin, and polyvinyl alcohol resin. For the adhesive layer 16, it is preferable to use one that has high adhesiveness that allows it to adhere uniformly to the base paper 14 of the paper container PC.

[0035] An example of the structure of the film FL is shown below. The left side of the example structure is the base paper 14, and the right side is the inner surface IS side of the composite container 10. In the structure below, a molten thermoplastic resin is formed into a film, and is not dispersed, dissolved, or emulsified in water or a solvent like an adhesive. The combination of materials that make up the film FL can be changed as appropriate, as long as it has the functions of the adhesive layer 16, intermediate layer 17, and base layer 18. <Example of Film FL composition> (Base paper side) PE / EVOH / Ny / PP (Inner surface of composite container) (Base paper side) PP / EVOH / Ny / PP (Inner surface of composite container) (Base paper side) PE+PP / EVOH / Ny / PP (Inner surface of composite container) (Base paper side) EVA / EVOH / Ny / PP (Inner surface of composite container) (Base paper side) PE / EVOH / Ny / PE (Inner surface of composite container) (Base paper side) EVA / EVOH / Ny / PE (Inner surface of composite container) (Base paper side) PP / Ny / PP (Inner surface of composite container) (Base paper side) PE / Ny / PP (Inner surface of composite container) (Base paper side) PE+PP / Ny / PP (Inner surface of composite container) (Base paper side) EVA / Ny / PP (Inner surface of composite container) (Base paper side) PE / Ny / PE (Inner surface of composite container) (Base paper side) EVA / Ny / PE (Inner surface of composite container) (Base paper side) EVA / EVOH / Ionomer / PE (Inner surface of composite container) (Base paper side) PE / EVOH / Ionomer / PE (Inner surface of composite container) (Base paper side) PP / EVOH / Ionomer / PP (Inner surface of composite container) (Base paper side) PE / EVOH / Ionomer / PP (Inner surface of composite container) (Base paper side) EVA / EVOH / Ionomer / PP (Inner surface of composite container) (Base paper side) PE+PP / EVOH / Ionomer / PP (Inner surface of composite container)

[0036] The film FL is thick enough to deform along the inner surface IS of the paper container PC during pressure forming and to prevent pinholes from forming. The overall thickness of the film FL before application is, for example, 90 μm to 250 μm, preferably 100 μm. The combined thickness of the base layer 18 and intermediate layer 17 is, for example, 60 μm to 80 μm, and the thickness of the adhesive layer 16 is, for example, 20 μm to 40 μm. The composition ratio of the adhesive layer 16, intermediate layer 17, and base layer 18 is, for example, adhesive layer:(intermediate layer and base layer) = 2:8 to 4:6, and can be changed as appropriate as long as the barrier properties and adhesiveness of the film FL are maintained. The performance of the film FL is largely influenced by its thickness and less by its ratio. For example, the overall thickness of the film FL affects the tearing of the film FL during application. Furthermore, if the film FL contains Ny, EVOH, or ionomer, the film FL becomes less likely to tear. The adhesion between the film FL and the base paper 14 is affected by the thickness of the adhesive layer 16. The effect of the thickness of the adhesive layer 16 also varies depending on the type of resin used in the adhesive layer 16. Furthermore, in the film FL, the oxygen barrier property is affected by the thickness of the EVOH, which has oxygen barrier properties.

[0037] The film application device 100 shown in Figure 5 includes a lower mold member 20, a compressed air device 30, a support member 40, an air adjustment unit 50, an air suction unit 60, and a control device 80. The film application device 100 applies a film FL or film material FM to the inner surface IS or adhesive surface BS of a paper container PC by using an air pressure difference. As will be described in detail later, the air pressure difference is generated by either introducing compressed air from above the film FL or by drawing a vacuum from below the paper container PC.

[0038] The lower mold member 20 includes a cylindrical cavity 21, a disk-shaped pedestal 22, and an annular film holding member 23. The lower mold member 20 also includes a disk-shaped base 25 that aligns and fixes the cavity 21 and the pedestal 22 to each other, and a support 26 that fixes the film holding member 23 above the outer periphery of the base 25. The cavity 21 and the pedestal 22 stably support the precursor paper container PC in the lower mold member 20. A gap GA is formed between the lower inner surface of the cavity 21 and the periphery of the pedestal 22, and air vent paths 28a and 28b are formed below the pedestal 22. Air around the paper container PC can be discharged to the air suction unit 60 via the gap GA and the air vent paths 28a and 28b.

[0039] The compressed air device 30 is a disk-shaped member that incorporates a heater 31 and has multiple vents 33. An annular cutter 35 is fixed to the outer periphery of the compressed air device 30, and cuts out a processed portion FLa to be attached to the inner surface IS of the paper container PC from the sheet-like film material FM that has moved above the lower mold member 20. The processed portion FLa corresponds to the film FL of the composite container 10 shown in FIG. 1A and other figures. The compressed air device 30 is driven by an elevation drive device 71 and can be raised and lowered in a vertical direction parallel to the axis AX. When the compressed air device 30 is raised, the paper container PC can be placed in the lower mold member 20. When the compressed air device 30 is lowered, the film material FM can be pressure-bonded to the mouth portion PCa formed at the top of the paper container PC, and the cutter 35 can cut out the processed portion FLa from the film material FM. The heater 31 can be driven by a heater driving device 72 to adjust its temperature, thereby softening the processed portion FLa of the film material FM. The air pressure device 30 can reduce the pressure of the space facing the lower surface 30a of the air pressure device 30 through the vent 33 using the air adjustment unit 50, allowing the processed portion FLa of the film material FM to be tightly attached to the lower surface 30a. This allows the film material FM to be held and softened to a desired state. The lower surface 30a of the air pressure device 30 has a curved shape. This allows the processed portion FLa to be attached to the lower surface 30a while being heated from the edge and wrinkles are smoothed out. The lower surface 30a is not limited to a curved shape, and may be flat.

[0040] The support member 40 temporarily fixes the film material FM to the paper container PC by sandwiching the film material FM between it and the film holding member 23 of the lower mold member 20. The support member 40 is driven by an elevation drive device 73 and can be raised and lowered in the vertical direction parallel to the axis AX. When the support member 40 is raised, the film material FM can be moved horizontally above the paper container PC, and when the support member 40 is lowered, the film material FM is sandwiched and fixed between the upper surface 23a of the film holding member 23 and the lower surface 40a of the support member 40.

[0041] The air adjustment unit 50 is an air suction device and also functions as a compressed air blowing device. The air adjustment unit 50 is connected to the vent 33 of the compressed air device 30. The air adjustment unit 50 operates as an air suction device at a predetermined timing, adsorbing the processed portion FLa of the film material FM to the lower surface 30a of the compressed air device 30 and softening it. The air adjustment unit 50 operates as a compressed air blowing device at a predetermined timing, stretching the softened processed portion FLa with compressed air introduced from above and deforming it so that it is pressed against the inner surface IS of the paper container PC. The compressed air supplied by the air adjustment unit 50 from the vent 33 may have a temperature adjusted so that the softening degree of the processed portion FLa of the film material FM is maintained.

[0042] The air suction unit 60 can vacuum the cavity 21 of the lower mold member 20 through the gap GA and the air passages 28a, 28b to reduce the pressure, and can reduce the pressure around the paper container PC placed on the lower mold member 20. This makes it easy to bring the stretched processed portion FLa of the film material FM into close contact with the inner surface IS of the paper container PC when the processed portion FLa of the film material FM is blown with compressed air.

[0043] The control device 80 comprehensively controls the operation of the film application device 100. The control device 80 controls the temperature of the compressed air device 30 by controlling the drive state of the heater drive device 72 and adjusts the elevated position of the compressed air device 30 by controlling the drive state of the lift drive device 71. The control device 80 adjusts the elevated position of the support member 40 by controlling the drive state of the lift drive device 73. The control device 80 controls the drive state of the air adjustment unit 50 to bring the processed portion FLa of the film material FM into close contact with the lower surface 30a of the compressed air device 30 at the desired timing, and to deform the softened processed portion FLa so as to press it against the inner surface IS of the paper container PC. At this time, the control device 80 controls the drive state of the air suction unit 60 in synchronization with the air adjustment unit 50 to reduce the pressure around the paper container PC and assist in bringing the stretched processed portion FLa of the film material FM into close contact with the inner surface IS of the paper container PC.

[0044] A method for manufacturing the composite container 10 will be described below with reference to Figures 6 and 7. The device used to form the paper container PC is not shown.

[0045] (Forming of Paper Container) First, as shown in Fig. 6, a base paper 14 for a paper container PC is prepared, and a printed layer 15 is formed on the surface that will become the outer surface OS of the paper container PC as needed (step S11). The printed outer surface OS may be laminated.

[0046] Next, adhesive HS is applied to predetermined locations on the surface of the body member 11 that will become the inner surface IS of the paper container PC (adhesive application step, step S12). The locations to which the adhesive HS is applied are the portions corresponding to the side joints 13a (sides SD), the portion corresponding to the bottom joint 13b (bottom BT), and the portion corresponding to the curled portion PCb at the top of the bottom plate member 12 (top TP). The adhesive HS is applied to the body member 11 by printing or the like. The marks on the printed layer 15 are used as a reference for alignment when applying the adhesive HS. Before or after step S12, the outer surface OS of the base paper 14 may be laminated.

[0047] Next, the base paper 14 is cut out into the body member 11 and the bottom plate member 12, which are parts (blanks) of the paper container PC (step S13). When cutting out the blanks, the marks on the print layer 15 are used as references.

[0048] Next, the body member 11 and the bottom plate member 12 are joined together to assemble the paper container PC into a cup shape (joining process, step S14). The paper container PC is molded using a molding device (not shown). The body member 11 and the bottom plate member 12 are joined together by heating the bonding agent HS. The heating temperature is equal to or higher than the melting point of the bonding agent HS, preferably 200°C to 500°C.

[0049] After the body member 11 and the bottom plate member 12 are joined, a lubricant is applied to the upper part (top TP) of the inner surface IS of the body member 11 (lubricant application step, step S15). Because the bonding agent HS has been applied to the upper part of the body member 11 in advance in step S12, the lubricant does not easily penetrate into the base paper 14, making it easier to form the curled portion PCb in the next step.

[0050] After the lubricant is applied, the upper part of the paper container PC is rolled outward to form a curled portion PCb (curled portion forming step, step S16).

[0051] (Film application to paper container) The paper container PC formed in steps S11 to S16 is set in the film application device 100 (step S21). Specifically, the paper container PC is stored in the lower mold member 20 of the film application device 100. At this time, the control device 80 operates the compressed air device 30 and the support member 40 to separate the compressed air device 30 and the support member 40 from the lower mold member 20.

[0052] Next, the film material FM to be attached to the inner surface IS of the paper container PC is supplied to the film attachment device 100 (step S22). Specifically, the control device 80 moves the film material FM horizontally above the paper container PC with the support member 40 raised (see FIG. 7A).

[0053] Next, a processed portion FLa is cut from the film material FM to match the shape of the mouth portion PCa of the paper container PC (step S23). Specifically, the control device 80 lowers the support member 40, sandwiching and fixing the film material FM between the upper surface 23a of the film holding member 23 and the lower surface 40a of the support member 40. The control device 80 also lowers the compressed air device 30, pressurizing the film material FM onto the mouth portion PCa of the paper container PC, and cutting out the processed portion FLa from the film material FM with the cutter 35.

[0054] Next, the processed portion FLa of the cut film material FM is attached to the compressed air device 30 of the film attachment device 100, and the processed portion FLa is heated (film heating step, step S24). Specifically, the control device 80 operates the air adjustment unit 50 to suck in air AR1 through the vent 33, and adsorbs the processed portion FLa to the underside 30a of the compressed air device 30 (see FIG. 7B). The control device 80 also operates the heater 31 to soften the processed portion FLa adsorbed to the compressed air device 30. The heating temperature of the heater 31 is equal to or higher than the melting point of the resin constituting the adhesive layer 16, preferably 160°C to 190°C.

[0055] Next, while the paper container PC is vacuumed, the processed portion FLa of the film material FM is pressure-molded and attached to the inner surface IS of the paper container PC (film attachment process, step S25). The processed portion FLa is attached to the flange P1, body inner wall P2, bottom P3, and V zone VZ of the paper container PC in that order. This ensures the thickness of the film FL and allows the film FL to be tightly attached to the inner surface IS of the paper container PC without leaving any air between the paper container PC and the film FL. Note that the film FL is not attached to the V zone VZ. However, in the V zone VZ, the film FL is not directly attached to the inner surface IS of the paper container PC, but is close to the inner surface IS and does not float. Specifically, the control device 80 operates the compressed air device 30 to introduce compressed air AR2 from above the processed portion FLa through the air vent 33, stretching the softened processed portion FLa and deforming it so that it presses against the inner surface IS of the paper container PC (see FIG. 7C). The control device 80 also operates the air suction unit 60 to draw a vacuum and exhaust air VA through the gap GA (see FIG. 5) and the air passages 28a, 28b to reduce the pressure around the paper container PC, and in cooperation with the compressed air blow by the compressed air device 30, attaches the processed portion FLa as a film FL to the inner surface IS of the paper container PC (see FIG. 7C). The heated film FL is molded by the air pressure difference, which improves the moldability and adhesion of the film FL to the paper container PC.

[0056] Finally, the composite container 10 with the film FL attached to the paper container PC is removed from the film attachment device 100 (step S26). Specifically, the control device 80 operates the compressed air device 30 and the support member 40 to raise the compressed air device 30 and the support member 40, and removes the composite container 10 from the lower mold member 20.

[0057] In the above, the film FL was attached by utilizing the air pressure difference caused by both the introduction of compressed air (compressed air molding) and vacuum drawing, but the film FL may also be attached by utilizing the air pressure difference caused by either compressed air molding or vacuum drawing.

[0058] (Example) Hereinafter, the formability of a paper container and the adhesiveness of a film to the paper container will be described as an example. In the example, the base paper 14 of the body member 11 and the bottom plate member 12 has a basis weight of 300 g / m ２ The base paper 14 used was HC(E)COC (manufactured by O&C Ivory Board Co., Ltd.), which is a 100% polyester resin. The outer surface OS of the body member 11 was printed using OP varnish (overprint varnish). The air permeability (Oken air permeability) of the base paper 14 with the outer surface OS coated with OP varnish was 624 sec. The bonding agent HS used was an ionomer such as Chemipearl S500 (registered trademark, manufactured by Mitsui Chemicals, Inc.). The coating amount of bonding agent HS was 9.4 g / m. ２ is.

[0059] (A) Formability of Paper Containers Figures 8A and 8B show the relationship between the bottom coat area of ​​the adhesive HS in a paper container PC and the formability of the paper container PC. The bottom coat area is the area coated with the adhesive HS in the bottom BT shown in Figures 9A to 9D. Figure 9A shows the case where the bottom coat area is 0%, Figure 9B shows the case where the bottom coat area is 26%, Figure 9C shows the case where the bottom coat area is 90%, and Figure 9D shows the case where the bottom coat area is 100%. The bottom coat area is the total area of ​​one or more bottom coated portions CC of the bottom BT, excluding the bottom non-coated portion NC1. In the examples, the number of bottom coated portions CC was set to 20, and the bottom coat area was increased or decreased by changing the area of ​​each bottom coated portion CC. The bottom coated portions CC had uniform widths or areas and were spaced at regular intervals. When the bottom coat area is 0%, no bottom coating portion CC is provided, and the bonding agent HS is not applied to the bottom BT (see FIG. 9A). When the bottom coat area is 100%, the entire bottom BT is the bottom coating portion CC, and the bonding agent HS is applied to the entire bottom BT (see FIG. 9D). In FIG. 8A, the number of bottom coating portions CC when the bottom coat area is 100% is 20, assuming that there are no gaps between the bottom coating portions CC.

[0060] By making the bottom coating portions CC uniform in width or area, the bonded portions between the body member 11 and the bottom plate member 12 are spaced apart at regular intervals with uniform widths or areas. This allows air to escape uniformly through the ventilation portions AP, which are the non-bonded portions NB. This prevents stress from being placed on any one of the multiple ventilation portions AP, making it less likely for the film FL to tear. The bottom coat gap BG (see FIG. 1B) shown in FIG. 8A corresponds to the widest width of each non-bonded portion NB shown in FIG. 1B and is the inlet through which air VA (see FIG. 7C) passes. As shown in FIG. 8A, the width of the bottom coat gap BG must be 4 mm or more. This allows air to escape uniformly through the multiple ventilation portions AP (see FIG. 2B) to prevent lifting of the film FL in the V zone VZ.

[0061] In Figure 8A, the moldability of the paper container PC was evaluated as "good" when the shape of the paper container PC was maintained and continuous molding was possible. When the bottom coat area was 26% to 100%, the moldability of the paper container PC was good. However, when the bottom coat area was 20% or less, the adhesion between the body member 11 and the bottom plate member 12 peeled off when the paper container PC was discharged after molding, making continuous molding difficult.

[0062] The adhesive strength of the bottom plate member 12 required for continuous molding of the paper container PC was measured. The adhesive strength of the bottom plate member 12 was measured by compressing the bottom plate member 12 from the underside or the bottom side of the paper container PC using a strength tester (specifically, a Strograph), and measuring the strength at which the bottom plate member 12 began to peel. The diameter of the compression jig of the strength tester was 106 mm corresponding to the shape and size of the paper container PC, and the compression speed was 100 mm / min.

[0063] Figure 8B shows the adhesive strength of the bottom plate member 12. As shown in Figure 8B, it was found that an adhesive strength of 52 N or more is required to continuously mold the paper container PC. When the adhesive strength is 52 N or more, delamination of the paper layers occurs in the paper container PC after the bottom plate member 12 is peeled off, indicating that the body member 11 and the bottom plate member 12 are sufficiently bonded. Note that when the bottom coat area is 20% or less, the adhesive strength of the bottom plate member 12 is weak and the bottom plate member 12 is prone to coming loose.

[0064] (B) Film Adhesion to Paper Containers Figure 8A shows the relationship between the formability of the film FL to the paper container PC and tearing of the film FL. The heating conditions for attaching the film FL or the processed portion FLa to the paper container PC were a heating temperature of 177°C and a heating time of 1 second. The film FL was attached to the inner surface IS of the paper container PC by pressure molding at a compressed air pressure of 0.05 MPa to 0.15 MPa and a compressed air time of 1.2 seconds while evacuating at a vacuum pressure of -56 kPa. Regarding formability, if the film FL could be molded, the evaluation was marked "Good." Furthermore, the presence or absence of lifting of the film FL in the V zone VZ of the bottom joint 13b formed by the body member 11 and the bottom plate member 12 was determined, and if the lifting of the film FL was 3 mm or less, the evaluation was marked "Good." Regarding tearing of the film FL, the presence or absence of tearing of the film FL was determined, and if no tearing was found, the evaluation was marked "Good." It should be noted that tearing of the film FL is likely to occur in the V zone VZ.

[0065] As shown in Figure 8A, the adhesion of the film FL was good when the bottom coat area was 26% to 80%. When the bottom coat area was 90%, partial lifting of the film FL occurred in the V zone VZ, and when the bottom coat area was 100%, lifting of the film FL occurred around almost the entire periphery of the V zone VZ. The tearing of the film FL can be addressed by changing the compressed air pressure, the type of film FL, the thickness of the film FL, etc.

[0066] According to the composite container 10 and the manufacturing method for the composite container 10 described above, the base paper 14 is exposed at the adhesive surface BS between the paper container PC and the film FL, and the film FL has the adhesive layer 16, which makes it possible to stabilize the adhesion between the paper container PC and the film FL. Furthermore, because the adhesive agent HS is used at the side joint portion 13a and the bottom joint portion 13b, i.e., the joint portions necessary for forming the paper container PC, the amount of resin applied to the paper container PC can be reduced while maintaining film adhesion over the entire inner surface IS of the paper container PC.

[0067] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments and various modifications are possible.

[0068] In the above embodiment, the film FL may be a single layer consisting of only the adhesive layer 16. That is, the base material layer 18 and the intermediate layer 17 may be omitted from the film FL. Even in the case of a single layer, the constituent material is not limited to one type, and may be a mixture of two or more types of resin, such as a combination of PP and PE. Furthermore, the film FL may be formed of only the adhesive layer 16 and the base material layer 18, omitting the intermediate layer 17.

[0069] In the above embodiment, the bonding agent HS does not have to be applied to the entire surface of the side SD. That is, the side application portion SS of the bonding agent HS does not have to cover the entire surface of the side SD. For example, as illustrated in Figures 10A to 10C, the bonding agent HS may have a side non-application portion NC2 on the side SD. The width of the side non-application portion NC2 is narrower than the width of the bottom non-application portion NC1 shown in Figure 1B.

[0070] In the above embodiment, the application position of the adhesive HS in the bottom joint portion 13b can be changed as appropriate. For example, as shown in Figure 11A, in the vertical direction of the body member 11, the bottom application portion CC may be an area extending to the middle portion of the bottom BT rather than the area extending to the lowest end of the bottom BT. Figures 11B and 11C are enlarged cross-sectional views of the area around the bottom joint portion 13b of the molded paper container PC. The state of bonding between the bottom 11b of the body member 11 and the bottom plate member 12 changes depending on the application position of the bottom application portion CC.

[0071] FIG. 11B shows an example of bonding between the adhesive HS applied to the body member 11 and the peripheral wall portion 12b and edge portion 12d of the bottom plate member 12. FIG. 11C shows an example of bonding between the adhesive HS applied to the body member 11 and the peripheral wall portion 12b of the bottom plate member 12. At the bottom joint portion 13b shown in FIGS. 11B and 11C, the back surface 12f of the bottom plate member 12 and the inner surface 11f of the body member 11 are not bonded. Therefore, at the bottom joint portion 13b, the inner wall portion 11bb of the body member 11 is easily separated from the peripheral wall portion 12b of the bottom plate member 12. In this case, the ventilation area of ​​the inner wall portion 11bb in the ventilation portion AP is increased, allowing for vacuuming in a short time. As a result, uniform air exhaust at the ventilation portion AP, shorter film forming time, and reduced compressed air pressure are possible. Furthermore, after the content of the composite container 10 is heated in a microwave oven, when a user holds the composite container 10 by hooking his / her fingers on the bottom 11b or threaded bottom, the inner wall 11bb separated from the bottom plate member 12 gets in the way, making it difficult for the user to touch the bottom surface of the composite container 10, thereby preventing burns.

[0072] The application position of the adhesive HS in the bottom joint portion 13b may be divided into two areas in the vertical direction. For example, the bottom application portion CC may be divided into an area extending from the upper end to the middle of the bottom BT and an area toward the lower end of the bottom BT in the vertical direction of the body member 11. In this case, as shown in Figures 11D and 11E, the outer wall portion 11ba of the body member 11 is joined to the peripheral wall portion 12b of the bottom plate member 12, and a portion of the inner wall portion 11bb of the body member 11 is joined to a portion of the peripheral wall portion 12b of the bottom plate member 12 (the upper end portion or the middle portion of the back surface 12f of the peripheral wall portion 12b in a cross-sectional view). In this case, the adhesive HS applied to the body member 11 is bonded to both sides of the peripheral wall portion 12b of the bottom plate member 12, making it more difficult for the inner wall portion 11bb to separate from the peripheral wall portion 12b than when the adhesive HS is bonded to only one side of the peripheral wall portion 12b.

[0073] In the above embodiment, the bonding agent HS may be applied to the outer periphery 12c of the bottom plate member 12 without being applied to the body member 11. As shown in Fig. 12A, on the outer periphery 12c of the bottom plate member 12, multiple bottom application portions CC are radially arranged in an area corresponding to the bottom BT. Fig. 12B is an enlarged cross-sectional view of the area around the bottom joint portion 13b of the molded paper container PC. At the bottom joint portion 13b shown in Fig. 12B, the back surface 12f of the bottom plate member 12 and the inner surface 11f of the body member 11 are not joined.

[0074] In the above embodiment, the composite container 10 is not limited to one having a circular shape in a plan view, but may have various polygonal or elliptical shapes.

[0075] In the above embodiment, the film material FM is not limited to being cut and then the processed portion FLa is heated as shown in FIG. 7B . Alternatively, the film material FM may be sandwiched between separate heating plates (not shown) on both sides and then fed into the film laminating device 100 while being heated. Alternatively, the film material FM or the processed portion FLa may be heated by radiant heat from a ceramic heater or the like. In this case, the heater 31 of the compressed air device 30 may be omitted as long as the softening of the film FL can be maintained.

[0076] In the above embodiment, the film FL is heated and molded, but the film FL may also be molded in a state where the paper container PC is also heated.

[0077] In the above embodiment, the bottom plate member 12 is folded and attached to the bottom portion 11b of the body member 11. However, as shown in FIG. 13, the body member 11 may be folded without folding the bottom plate member 12, and the bottom portion 11b of the body member 11 may be attached to the bottom plate member 12.

[0078] In the above embodiment, the curled portion PCb may not be provided on the mouth portion PCa or flange P1 of the composite container 10. In this case, as shown in Fig. 14A, the flange end surface FF of the composite container 10 is formed sideways. Alternatively, as shown in Fig. 14B, the flange end surface FF of the composite container 10 is formed facing upward. In the case of such a flange P1, the method of attaching the film FL may be changed as appropriate to the shape of the mold, or to a method in which the film material FM is heated in advance with radiant heat, and then vacuum-pressure-molded onto the paper container PC, which serves as the lower mold, while ensuring a film area to be wrapped around the flange end surface FF.

[0079] In the above embodiment, the curled portion PCb may be formed after the film FL is attached. Specifically, the paper container PC is first molded without forming the curled portion PCb. Then, as shown in FIG. 14B, the flange end surface FF of the composite container 10 is formed facing upward. The film FL or film material FM is heated in advance with radiant heat, and then attached to the paper container PC in the lower mold by vacuum and pressure forming, while ensuring a film area to be wrapped around the flange end surface FF. At this time, the base paper 14 of the paper container PC is not cut. As shown in FIG. 14C, after the film is attached, the film FL and base paper 14 are curled together to form the curled portion PCb.

[0080] In the above embodiment, the ventilation area AP provided in the bottom joint portion 13b is formed by the non-bonded portion NB of the body member 11, which is the bottom non-application portion NC1 of the adhesive HS. However, it may be formed by other methods. For example, as shown in FIG. 15 , the ventilation area AP may be formed by drilling a hole HL or perforations slightly below the portion of the body member 11 corresponding to the V zone VZ. In this case, the bottom joint portion 13b is bonded by applying the adhesive HS to the entire surface of the bottom BT of the body member 11, as shown in FIG. 9D . The application position of the adhesive HS is adjusted so that the hole HL or the like is exposed, allowing ventilation through the ventilation area AP.

[0081] The present invention is not limited to the above-described embodiments, and it is clear that each embodiment can be appropriately modified or changed within the scope of the technical concept of the present invention. The technology of each embodiment can be used in other embodiments as long as no technical contradiction occurs.

[0082] This application claims priority based on Japanese Patent Application No. 2023-057757, filed on March 31, 2023, the entire disclosure of which is incorporated herein by reference.

Claims

1. The paper container includes a body member and a bottom plate member joined together, and a resin film attached to the inner surface of the paper container, The paper container has a base paper exposed at the adhesive surface between the paper container and the film, In the paper container, a side joint portion that joins the side surfaces of the body member and a bottom joint portion that joins the body member and the bottom plate member are each joined via an adhesive, The composite container has an adhesive layer that adheres to the base paper of the paper container.

2. The composite container according to claim 1 , wherein a part of the bottom joint has a ventilation part that allows ventilation to the outside of the paper container.

3. The paper container has a curled portion in which an upper portion of the body member is curled outward, The composite container according to claim 1 or 2, wherein a portion of the inner surface of the paper container that corresponds to the curled portion has the bonding agent.

4. 3. The composite container according to claim 1, wherein the thickness of the film varies depending on the position of adhesion to the paper container, and the film adhered to the bottom of the paper container is thicker than the film adhered to the inner wall of the body.

5. A method for manufacturing a composite container comprising a paper container formed by joining a body member and a bottom plate member, and a resin film attached to the inner surface of the paper container, The paper container has a base paper exposed at the adhesive surface between the paper container and the film, The film has an adhesive layer that adheres to the base paper of the paper container, a bonding agent application step of applying a bonding agent to portions of the inner surface of the paper container that correspond to side bonding portions that bond the side surfaces of the body member and a bottom bonding portion that bond the body member and the bottom plate member; a joining step of joining the side joining portions and the bottom joining portion, a film attaching step of attaching the film to the adhesive surface of the paper container by an air pressure difference; A method for manufacturing a composite container comprising:

6. The method for manufacturing a composite container according to claim 5 , wherein a part of the bottom joint has a ventilation part that allows ventilation to the outside of the paper container by the air pressure difference.

7. The paper container has a curled portion in which an upper portion of the body member is curled outward, The method for manufacturing a composite container according to claim 5 or 6, wherein in the bonding agent application step, the bonding agent is applied to a portion of the inner surface of the paper container that corresponds to the curled portion.

8. a film heating step of heating the film, The method for manufacturing a composite container according to claim 5 or 6, wherein in the film attaching step, the film heated by the air pressure difference is attached to the adhesive surface of the paper container.

9. The method for manufacturing a composite container according to claim 5 or 6, wherein the pressure difference is generated by either introducing compressed air from above the film or drawing a vacuum from below the paper container.

10. The method for manufacturing a composite container according to claim 5 or 6, wherein the film is adhered to the flange, the inner wall of the body, the bottom, and the V-zone of the paper container in this order.