Blank for container and paper resin composite container

Abstract

To provide a blank for a container capable of maintaining each panel at a proper position with respect to a metal mold and preventing exposure of an end surface of each panel after molding, and a paper resin composite container.SOLUTION: A blank for a container comprises a bottom panel corresponding to a bottom surface of the container, and at least one side panel corresponding to a side surface of the container and continuously contacting a peripheral edge part of the bottom panel. The bottom panel and the side panel are integrally molded into a planar shape, and include a paper layer and a stretched film layer. At both ends of a bending line provided at a boundary of the bottom panel and the side panel, an arcuate crotch part having a center of curvature at an outer area between the bottom panel and the side panel is formed. A curvature radius (R) of the crotch part is 1.0 mm or more.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a container blank and a paper-resin composite container. [Background technology]

[0002] As a paper-resin composite container, a technology is known in which a blank plate made of a laminated sheet of at least paper and plastic film is inserted into a mold and the resin and the blank plate are integrated by injection molding, as described in Patent Document 1. In one example described in Patent Document 1, a tapered round composite container is manufactured by using a blank plate made of a circular bottom plate and a sector-shaped body plate connected to the bottom plate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-207880 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned conventional technology, the shape of the part where the bottom plate and the shell plate are connected is not particularly considered. When the shell plate (side panel) is bent relative to the bottom plate (bottom panel) and a composite container is manufactured by injection molding, the base part of the shell plate (near the boundary between the shell plate and the bottom plate) may be torn or broken. In such a case, for example, the position of the shell plate may be misaligned relative to the mold, and as a result, the end face of the blank in the composite container may be exposed and not covered by resin.

[0005] An object of the present invention is to provide a container blank and a paper-resin composite container that can maintain each panel in the correct position relative to the mold and prevent the end faces of each panel from being exposed after molding. [Means for solving the problem]

[0006] [1] A container blank according to one embodiment of the present disclosure comprises a bottom panel corresponding to a bottom surface of the container, and at least one side panel corresponding to a side surface of the container and connected to a peripheral portion of the bottom panel, the bottom panel and the side panel being integrally molded into a planar shape and including a paper layer and a stretched film layer, and an arc-shaped crotch portion having a center of curvature in an external area between the bottom panel and the side panel is formed at both ends of a fold line provided at the boundary between the bottom panel and the side panel, and the radius of curvature (R) of the crotch portion is 1.0 mm or more.

[0007] According to the container blank of [1], the bottom panel and the side panel include a paper layer and a stretched film layer. The radius of curvature (R) of the crotch portion formed at both ends of the folding line at the boundary between them is 1.0 mm or more, so that the crotch portion is less likely to tear or break. Therefore, the bottom panel and the side panel can be maintained in the proper position relative to the mold. As a result, in the paper-resin composite container after molding, the end faces of the bottom panel and the side panel can be prevented from being exposed. If the end face of any panel in the container is exposed, there is a risk that the contents will permeate or leak, or the rigidity of the paper will decrease due to water wetting when the container is used in a water environment, resulting in the physical strength of the container being affected. Such an event is prevented by the container blank of [1].

[0008] [2] In the container blank described in [1] above, the stretched film layer may be disposed on the inner side of the paper layer. In this case, the crotch portion is even less likely to tear.

[0009] [3] In the container blank according to the above item [1] or [2], the stretched film layer may have a barrier property. In this case, the barrier property is imparted to a paper-resin composite container produced from the container blank.

[0010] [4] In the container blank described in [3] above, the stretched film layer may include a vapor deposition layer to impart barrier properties thereto.

[0011] [5] In the container blank described in [3] above, the stretched film layer may have a coating layer on at least one surface thereof, the coating layer including a barrier coating material consisting of at least one of a barrier resin and a binder resin.

[0012] [6] In the container blank according to any one of the above [1] to [5], the content of the paper layer may be 50% by weight or more. A high content of the paper layer contributes to reducing the environmental load.

[0013] [7] As another aspect of the present invention, a paper-resin composite container may be provided, which comprises a three-dimensional blank formed by folding the side panel of the container blank according to any one of [1] to [6] above along the folding line relative to the bottom panel, and a resin skeleton part that extends along the bottom or side surface so as to cover the end surfaces of the bottom panel and the side panel and is integrated with the three-dimensional blank. According to the paper-resin composite container of [7], the end surfaces of the bottom panel and the side panel are covered by the resin skeleton part, and the end surfaces are not exposed. Thus, a paper-resin composite container with the desired strength is realized. The above-mentioned penetration and leakage of the contents are also prevented. Effect of the Invention

[0014] According to the present invention, the bottom panel and side panel can be maintained in the correct position relative to the mold, and as a result, exposure of the end faces of the bottom panel and side panel can be prevented in the molded paper-resin composite container. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of a paper-resin composite container according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing an end surface portion of a three-dimensional blank in the paper-resin composite container of FIG. [Diagram 3] FIG. 3 is a plan view of a container blank according to one embodiment of the present invention. [Figure 4] FIG. 4 is an enlarged plan view of the container blank of FIG. [Diagram 5] FIG. 5 is a diagram showing the relationship between the radius of curvature of the crotch portion and the tear strength. [Figure 6] 6(a) to 6(e) are cross-sectional views showing the layer structure of container blanks according to the respective examples. [Figure 7] 7(a) to 7(d) are cross-sectional views showing layer structures of container blanks according to the respective comparative examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings as needed, but the present invention is not limited to the following embodiments. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations will be omitted as appropriate.

[0017] A paper-resin composite container 1 and a container blank 10 according to an embodiment of the present invention will be described with reference to Figs. 1, 2, and 3. As shown in Fig. 1, the paper-resin composite container 1 is a container for storing some kind of item in an internal space S, and has, for example, a circular bottom surface 5 and, for example, a cylindrical side surface 6 rising from the bottom surface 5. The paper-resin composite container 1 is a composite container in which a three-dimensional blank 20 obtained by three-dimensionally forming a container blank 10 (see Fig. 3) is integrated with a resin skeleton 30 by insert molding (injection molding using a mold). Since the container blank 10 includes a predetermined amount of paper layers, the paper-resin composite container 1 has a small amount of resin compared to its size (volume), and the environmental load is reduced. Hereinafter, the "paper-resin composite container 1" will be simply referred to as "container 1".

[0018] The article contained in the container 1 may be a food product or a non-food product such as cream or cosmetics. The article contained in the container 1 may be a liquid, solid, granule, powder, or a mixture containing one or more of these. When the article is a food product and liquid, the article may be, for example, a beverage such as water, tea, juice, lactobacillus drink, or alcoholic beverage. The container 1 may also contain an article that changes from a solid to a liquid depending on the outside temperature (for example, ice cream). Since the airtightness, liquidtightness, and barrier properties required for the container 1 change depending on the article (contents) to be contained, the layer structure of the three-dimensional blank 20 (container blank 10) may be appropriately changed or adjusted.

[0019] The container 1 is open at the top (opposite side to the bottom surface 5). An upper annular portion 33, which is a part of the resin skeleton portion 30, is formed above the side surface 6, and for example, a flange portion 36 and a threaded portion 37 are formed on the outer surface side of the upper annular portion 33. Both the flange portion 36 and the threaded portion 37 protrude outward from the cylindrical surface of the upper annular portion 33. The flange portion 36 is formed over the entire circumference (over the entire circumferential direction) at the lower end of the upper annular portion 33. The threaded portion 37 is formed, for example, in a part of the circumferential direction in the region above the flange portion 36, and constitutes a multi-threaded threaded portion. Note that the threaded portion 37 may be formed over the entire circumference. For example, a lid member (not shown) molded separately from the container 1 is attached to the upper annular portion 33. When the threaded portion 37 is provided, the lid member has a threaded portion on its inner surface that screws into the threaded portion 37.

[0020] The configuration of the upper part of container 1 can be changed as desired, and at least one of flange portion 36 and threaded portion 37 may be omitted. Threaded portion 37 may be omitted, and a lid member may be attached to the upper end surface of upper annular portion 33 by sealing (adhesion) or the like. When food (including beverages) is stored in container 1, the lid member cannot be attached to container 1 after opening, and may be a member that is discarded when the food is consumed.

[0021] The container 1 has a bottom surface 5 that is circular, elliptical, or of another shape including a curved peripheral portion. The container 1 is typically cylindrical or inverted truncated cone. Inverted truncated cone means that the container 1 has a tapered side surface 6 whose diameter increases upward (away from the bottom surface 5). The container 1 may also have a truncated cone shape. Even if the bottom surface 5 is not circular, the side surface may have a constant diameter or may have a tapered shape whose diameter changes. Even if the bottom surface 5 includes a curved peripheral portion, the container blank 10 allows each panel of the three-dimensional blank 20 to be suitably positioned, thereby realizing a container 1 with the desired strength.

[0022] The container blank 10 will be described with reference to FIG. 3. As shown in FIG. 3, the container blank 10 is formed into a flat shape and includes at least a paper layer and a stretched film layer. The layer structure of the container blank 10 is, for example, uniform throughout. The container blank 10 is manufactured by punching a sheet-like body having a laminated structure described below into an appropriate shape. Therefore, the layer structure is exposed on the end faces around the entire periphery of the container blank 10 (there is no layer extending in the thickness direction that covers the end faces).

[0023] The container blank 10 comprises a bottom panel 11 corresponding to the bottom surface 5 of the container 1, and two side panels 12 corresponding to the side surfaces 6 of the container 1. The bottom panel 11 and the two side panels 12 are integrally formed into a flat shape. The bottom panel 11 is, for example, a circular plate-like portion. The side panels 12 are, for example, a rectangular plate-like portion. A folding line L (see FIG. 4) is provided at each boundary between the bottom panel 11 and the two side panels 12.

[0024] The two side panels 12A, 12B are connected to opposite peripheral edges (at positions 180 degrees apart) of the bottom panel 11. The two side panels 12A, 12B have, for example, the same size and shape. The two side panels 12A, 12B are formed symmetrically with respect to an imaginary plane (a plane perpendicular to the bottom panel 11) that passes through the center of the bottom panel 11 and is equidistant from the two folding lines L. Each of the two side panels 12A, 12B includes a bottom side portion 12f that is slightly shorter than half the perimeter of the bottom panel 11 (a length equivalent to half the circumference). When the container 1 is cylindrical, each of the two side panels 12A, 12B includes a top side portion 12e that has a length equal to the bottom side portion 12f. The top side portion 12e is parallel to the bottom side portion 12f. The side portion 12g of the side panel 12 has an appropriate length according to the height of the container 1.

[0025] The side panel 12 of the container blank 10 corresponds to the side portion 22 of the side surface 6 of the container 1. The side portion 22 extends over a predetermined range less than 360 degrees. The two side surface panels 12A, 12B correspond to the side portion 22A, 22B of the side surface 6 of the container 1, respectively. Note that either one of the two side surface panels 12A, 12B may be omitted. In this case, the container blank 10 includes only one side surface panel 12. The one side surface panel 12 includes a bottom edge portion that is slightly shorter than the entire circumference of the bottom panel 11.

[0026] As shown in Fig. 3 and Fig. 4, linear incisions 15 may be formed along each folding line L. The incisions 15 do not reach both ends of the boundary (both ends of the folding line L), but are formed only near the center of the boundary. That is, the incisions 15 are shorter than the folding line L. The incisions 15 may be formed so as to penetrate the entire layer structure of the container blank 10 (the entire thickness direction), or may be formed only in a part of the inner surface or outer surface of the container blank 10 in the thickness direction (not penetrating). It is preferable to provide the incisions 15 (penetrating parts) in consideration of three-dimensionalization, but the incisions 15 may be omitted.

[0027] A pair of arc-shaped crotch portions 16 are formed at both ends of a folding line L provided at the boundary between the bottom panel 11 and the side panel 12. Two crotch portions 16 are formed for one folding line L (one side panel 12), and the container blank 10 has four crotch portions 16 as a whole.

[0028] As shown in FIG. 4, the crotch portion 16, which has a shape equivalent to a part of a circular arc, has a center of curvature O in an area between the bottom panel 11 and the side panel 12 and outside these (area outside the container blank 10). The crotch portion 16 is smoothly connected to the bottom side edge portion 12f of each side panel 12 and the peripheral edge portion 11e of the bottom panel 11. There is no corner (or sharp portion), i.e., no portion where the inclination of the tangent line changes suddenly, between the crotch portion 16 and the bottom side edge portion 12f and between the crotch portion 16 and the peripheral edge portion 11e. The angle A corresponding to the range in which the crotch portion 16 is formed is preferably within a range of 140 degrees to 170 degrees, and more preferably within a range of 150 degrees to 160 degrees. At both ends of the range in which the crotch portion 16 is formed (range of angle A), the tangent lines coincide with the bottom side edge portion 12f and also coincide with the tangent line of the peripheral edge portion 11e.

[0029] In the container blank 10 of this embodiment, the curvature radius R of the crotch portion 16 is preferably 1.0 mm or more. The curvature radius R of the crotch portion 16 is determined from the viewpoint of preventing the crotch portion 16 from being torn or broken during the manufacture of the container 1. That is, in the container blank 10 having the layer structure described below (including the stretched film layer), if the curvature radius R of the crotch portion 16 is less than 1.0 mm, the tear strength decreases (lower than when the stretched film layer is not included), and the possibility of the crotch portion 16 being torn or broken increases. In addition, even if a corner (or a sharp portion) exists between the crotch portion 16 and the bottom side portion 12f, such a portion is a factor that increases the possibility of tearing or breaking. In the container blank 10, an arc-shaped crotch portion is provided and its curvature radius R is determined in consideration of these factors.

[0030] More specifically, the radius of curvature R of the crotch portion 16 is determined based on the diameter (or radius) of the bottom panel 11, for example.

[0031] In addition, the ratio of the radius of curvature R of the crotch portion 16 to the radius of curvature R of the bottom panel 11 is preferably 9 or more. If the ratio of the radius of curvature R of the crotch portion 16 to the radius of curvature R of the bottom panel 11 is less than 9, gaps tend to be easily formed in the three-dimensional blank 20 when the container 1 is manufactured from the container blank 10. By maintaining the above ratio at 9 or more, the appearance is improved.

[0032] 1 and 2, a container 1 manufactured from the above-mentioned container blank 10 will be described. The container 1 is formed by folding two side panels 12A, 12B (at least one of the side panels 12) of the container blank 10 relative to the bottom panel 11 along two folding lines L to form a three-dimensional blank 20, to which a resin skeleton 30 is integrated. In the container 1, the end faces of the bottom panel 11 and the end faces of the side panels 12 are covered by the resin skeleton 30.

[0033] As shown in FIG. 1, the resin skeleton 30 extends along the bottom surface 5 and the side surface 6 of the container 1. The resin skeleton 30 includes a circular lower annular portion 31 formed along the boundary (ridge) between the bottom surface 5 and the side surface 6, the above-mentioned upper annular portion 33, and two side column portions 32 connecting the lower annular portion 31 and the upper annular portion 33. The side surface portions 22A and 22B correspond to the side panels 12A and 12B, respectively. As shown in FIG. 2, the upper end surface 22e of the side surface portion 22 corresponds to the top side edge portion 12e of the side panel 12. The upper end surface 22e is covered by at least one of the upper annular portion 33 and the flange portion 36. That is, the upper end surface 22e is contained within the resin skeleton 30 without being exposed or protruding from the resin skeleton 30 to the outside. In addition, a portion of the front surface 22c and a portion of the back surface 22d are covered by at least one of the upper annular portion 33 and the flange portion 36, but most of the front surface 22c and most of the back surface 22d are exposed and not covered by the resin skeleton portion 30.

[0034] In this way, the resin skeleton 30 covers the end faces of the three-dimensional blank 20, and also plays a role of forming the skeleton of the container 1, the part that ensures the strength, or the part that is functionally necessary (strength is also required) such as the screw part 37. The side end face of the side part 22 corresponding to the side edge part 12g of the side panel 12 is covered by two side column parts 32. The peripheral end face of the bottom part 21 corresponding to the peripheral edge part 11e of the bottom panel 11, the lower end face of the side part 22 corresponding to the bottom side edge part 12f of the side panel 12, the notch 15, and the above-mentioned crotch part 16 are covered by the lower annular part 31. As a result, the end faces of the entire area present in the three-dimensional blank 20 are covered by the three-dimensional blank 20.

[0035] The manufacturing method of the container 1 will be described. Planar container blanks 10 are stacked and stored at a predetermined position. Meanwhile, in an injection molding device, a mold consisting of a female mold and a male mold arranged to face each other is prepared. The outer shapes of these molds and the container blanks 10 are designed to correspond in advance. The container blanks 10 are taken one by one by a gripping device having a gripping mechanism such as a suction mechanism, and the container blanks 10 are attached to a dummy core having the same outer shape and size as the male mold. At this time, the inner side of the container blanks 10 abuts against the surface of the dummy core. The side panel 12 is folded relative to the bottom panel 11, and the container blanks 10 are held on the dummy core in the shape of a three-dimensional blank 20.

[0036] The dummy core holding the three-dimensional blank 20 is inserted into the female mold, and the holding by the dummy core is released. The dummy core is removed, and the three-dimensional blank 20 is set in the female mold. At this time, the outer surface side of the three-dimensional blank 20 abuts against the surface of the female mold. Each panel of the three-dimensional blank 20 is set in a predetermined position relative to the surface of the female mold. In this state, the male mold is inserted into the female mold. The clearance between the female mold and the male mold is narrowed, and the three-dimensional blank 20 is held down. During the process until the container blank 10 is set in the female mold, no tearing or breaking occurs in the crotch portion 16, so the position of the three-dimensional blank 20 in the mold is properly maintained. All end faces of the three-dimensional blank 20 face within the clearance and do not abut against the surface of either the female mold or the male mold.

[0037] After that, the resin material is filled through one or more gates formed in the mold, and injection molding is performed. This forms a resin skeleton 30 integrated with the three-dimensional blank 20, and the container 1 (paper-resin composite container) is manufactured. The injection molding device including the mold can be designed appropriately within the scope of known technology. The position of the gate may be set at an appropriate location of the lower annular portion 31 or the side column portion 32 of the container 1. An opening or the like may be provided in one of the panels of the container blank 10, and a gate may be provided in the opening.

[0038] Next, the resin material (molding resin) for forming the resin skeleton 30 and the layer structure of the container blank 10 will be described. The resin material as the molding resin is not particularly limited as long as it is a thermoplastic resin, and examples thereof include olefin resin, polyester resin, and polyamide resin from the viewpoint of processability and versatility. In addition, for the purpose of imparting barrier properties, a barrier resin such as ethylene vinyl alcohol or MXD nylon may be molded at the same time.

[0039] The container blank 10 includes at least a paper layer and a stretched film layer. In the container blank 10, the content of the paper layer is preferably 50% by weight or more, more preferably 60% by weight or more, and even more preferably 70% by weight or more.

[0040] The stretched film layer may have a barrier property. The barrier property will be described in detail later. When the stretched film layer has a barrier property, the stretched film layer is preferably disposed on the inner side of the paper layer (the inner side of the container, i.e., the back surface 22d side of the side panel 12).

[0041] The stretched film layer may be provided with the barrier properties by including a vapor deposition layer. Alternatively, the stretched film layer may have a coating layer on at least one surface thereof, the coating layer including a barrier coating material including one or more of a plate-like mineral, a barrier resin such as EVOH, and a binder resin. Alternatively, aluminum foil may be laminated as a barrier layer.

[0042] When the stretched film layer is disposed as the outermost layer, the stretched film layer must be made of a material that can be thermally welded to the molding resin.

[0043] A specific layer configuration (lamination structure) will be described with reference to Fig. 6. As shown in Fig. 6(a), the container blank of this embodiment includes, for example, a protective layer 51, an ink layer 52, a sealant layer 54, a paper layer 55, a polyethylene layer 58 (or an extruded polyethylene layer 58), a stretched film layer 56, and a second sealant layer 57, in this order from the outer layer (outer surface side) to the inner layer (inner surface side).

[0044] The protective layer 51 is a layer that protects the ink layer 52 and the paper layer 55. The protective layer 51 protects the ink layer 52 and the paper layer 55 by using a thermoplastic resin or OP varnish. When the protective layer 51 is a thermoplastic resin, it is preferable to use the same type of resin as the injection molding resin as the protective layer 51. Even if the protective layer 51 is a resin different from the injection molding resin, the resin material is not particularly limited as long as the welding strength is 5N / 15mm or more. If the welding strength is less than 5N / 15mm, the three-dimensional blank 20 may come off from the resin skeleton 30 during use, and the container 1 may no longer function. The resin of the innermost and outermost layers including the protective layer 51 is formed by film attachment, extrusion processing, coating, etc.

[0045] Known ink materials can be used for the ink layer 52. Whether or not to use the ink layer 52 is determined according to the appearance.

[0046] The paper layer 55 is a structural layer that imparts strength to the container blank 10 (three-dimensional blank 20). The type of paper used for the paper layer 55 is not particularly limited. In consideration of printability, it is desirable to use a paper with both glossiness as the paper layer 55. Waterproof paper or oil-resistant paper may be used as necessary. The basis weight of the paper layer 55 is not particularly limited. The thickness of the paper layer 55 is desirably within the range of, for example, 250 to 1000 μm. Note that, if the thickness of the paper layer 55 is less than 250 μm, molding is possible, but burrs may occur due to partial variations in the paper thickness, or the container strength against dropping or vibration may decrease due to lack of rigidity. Also, if the thickness of the paper layer 55 exceeds 1000 μm, the repulsion of the side portion 22 (side panel portion) becomes strong when three-dimensionalized, and the roundness of the container tends to decrease.

[0047] The polyethylene layer 58 functions as an adhesive for bonding the paper layer 55 and the stretched film layer 56. Therefore, the polyethylene layer 58 can also be called an adhesive layer.

[0048] The stretched film layer 56 is a layer for preventing tearing and breaking. The stretched film layer 56 is preferably disposed on the inner side of the paper layer 55. The stretched film layer 56 may be any material as long as it is a stretched substrate such as PET, Ny, or PP. An easy-to-cut film is not applied as the stretched film layer 56. That is, the stretched film layer 56 of this embodiment does not include an easy-to-cut film. The tensile strength of the stretched film layer 56 is preferably 100 MPa or more, more preferably 200 MPa or more. If the tensile strength is less than 100 MPa, the film is likely to be stretched and may break at the seam. The stretched film layer 56 may be uniaxially stretched or biaxially stretched. As described later, a barrier treatment such as inorganic vapor deposition or coating may be applied.

[0049] The stretched film layer 56 may have a deposition layer on at least one surface. The deposition layer is a layer formed above the resin substrate by depositing a deposition material in order to impart gas barrier properties. The deposition material used for the deposition layer may be appropriately selected from inorganic materials constituting known gas barrier deposition films. Examples of the deposition material include metals such as Si, Al, Zn, Sn, Fe, and Mn, and inorganic compounds containing one or more of these metals. Examples of the inorganic compound include oxides, nitrides, carbides, and fluorides. Among these, at least one selected from metals and metal oxides is preferable. Specifically, silicon oxides (SiO ) such as silicon monoxide and silicon dioxide are preferable. x ), aluminum oxide, magnesium oxide, tin oxide, etc.

[0050] Furthermore, in the stretched film layer 56, the surface of the resin substrate may be subjected to a surface treatment. By performing the surface treatment, it is possible to improve the adhesion with other layers (such as a vapor deposition layer or an anchor coat layer) when laminating the other layers. Here, the surface treatment may be, for example, (1) a physical treatment such as a corona treatment, a plasma treatment, or a flame treatment, or (2) a chemical treatment such as a chemical treatment using an acid or an alkali.

[0051] The stretched film layer 56 may have a coating layer on at least one surface thereof. The coating layer contains a water-soluble polymer (A) having water-solubility or water-dispersibility and an inorganic layered mineral (B) as constituent components.

[0052] [Water-soluble polymer (A)] The water-soluble polymer (A) is a polymer that can be completely dissolved or finely dispersed in water at room temperature. The water-soluble polymer (A) is not particularly limited as long as it is a compound that can penetrate and coordinate (intercalate) between the unit crystal layers of the inorganic layered mineral (B) described later, and examples thereof include polyvinyl alcohol and its derivatives, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, starches such as oxidized starch, etherified starch, and dextrin, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid or its esters, salts and their copolymers, copolymerized polyesters containing polar groups such as sulfoisophthalic acid, vinyl polymers such as polyhydroxyethyl methacrylate and its copolymers, or functional group-modified polymers such as carboxyl groups of these various polymers.

[0053] At least one of the water-soluble polymers (A) is preferably a polyvinyl alcohol polymer or a derivative thereof, and is particularly preferably a polyvinyl alcohol resin having a degree of saponification of 95% or more and a degree of polymerization of 300 or more. The higher the degree of saponification and the degree of polymerization of the polyvinyl alcohol resin, the lower the moisture absorption swelling property. If the degree of saponification of the polyvinyl alcohol resin is less than 95%, it is difficult to obtain sufficient gas barrier properties. On the other hand, if the degree of polymerization of the polyvinyl alcohol resin is less than 300, the gas barrier properties and the cohesive strength of the film are reduced.

[0054] [Inorganic layered minerals (B)] The inorganic layered mineral (B) is an inorganic compound in which extremely thin unit layers are stacked to form a layered particle. As the inorganic layered mineral (B), those that swell and cleave in water are preferable, and among these, clay compounds that have swelling properties in water are particularly preferably used. More specifically, the inorganic layered mineral (B) is a clay compound that has the property of absorbing and swelling water by coordinating it between extremely thin unit layers, and is generally Si4 + O2 - The layers are coordinated to form a tetrahedral structure, and the Al3 + , Mg2 + , Fe2 + , Fe3 + Etc., O2- and O.H. - The layers that form the octahedral structure by coordinating with the clay are bonded in a 1:1 or 2:1 ratio and stacked to form a layered structure. This clay compound may be natural or synthetic.

[0055] Representative examples of inorganic layered minerals (B) include hydrous silicates such as phyllosilicate minerals, for example, kaolinite clay minerals such as halloysite, kaolinite, endelite, dickite, and nacrite; antigorite clay minerals such as antigorite and chrysotile; smectite clay minerals such as montmorillonite, beidellite, nontronite, saponite, hectorite, sauconite, and stevensite; vermiculite clay minerals such as vermiculite; mica such as muscovite and phlogopite; mica or mica clay minerals such as margarite, tetrasilylic mica, and taeniolite. These inorganic layered minerals (B) are used alone or in combination of two or more. Among these inorganic layered minerals (B), smectite clay minerals such as montmorillonite and mica clay minerals such as water-swelling mica are particularly preferred.

[0056] The size of the inorganic layered mineral (B) is preferably an average particle size of 10 μm or less and a thickness of 500 nm or less. Among the inorganic layered minerals (B), at least one type of water-swellable synthetic mica having an average particle size of 1 μm to 10 μm and a thickness of 10 nm to 100 nm is particularly preferred. When water-swellable synthetic mica is used as the inorganic layered mineral (B), the water-swellable synthetic mica has high compatibility with the water-soluble polymer (A) and contains fewer impurities than natural mica, so there is no decrease in gas barrier properties or film cohesion due to impurities. In addition, since the water-swellable synthetic mica has fluorine atoms in its crystal structure, it also contributes to reducing the humidity dependency of the gas barrier properties of the film consisting of the coating layer. Furthermore, since the water-swellable synthetic mica has a high aspect ratio compared to other water-swellable inorganic layered minerals, the labyrinth effect works more effectively, and in particular, it contributes to the high expression of the gas barrier properties of the film consisting of the coating layer.

[0057] The solid content ratio of the inorganic layered mineral (B) in the total solid content of the coating layer is preferably 10% by mass to 70% by mass, and more preferably 15% by mass to 50% by mass. If the solid content ratio of the inorganic layered mineral (B) is less than 10% by mass, the labyrinth effect of the inorganic layered mineral (B) is not exhibited well, and the gas barrier property of the first coating film in a high humidity atmosphere is poor. On the other hand, if the solid content ratio of the inorganic layered mineral (B) exceeds 70% by mass, the coatability of the coating liquid and the adhesion to the substrate are poor.

[0058] The surface sealant layer 54 and the innermost sealant layer 57 are sealing layers with resin, and are layers that weld the resin skeleton 30 and the three-dimensional blank 20. On the other hand, if the material that forms the outermost layer of the container blank 10 does not have adhesion to resin, the surface sealant layer 54 is also required for adhesion to the resin skeleton 30 in the outermost layer. It is preferable to use the same type of resin as the injection molding resin for the surface sealant layer 54 and the innermost sealant layer 57. Even if the surface sealant layer 54 and the innermost sealant layer 57 are made of a resin different from the injection molding resin, the resin material is not particularly limited as long as the welding strength is 5N / 15mm or more, and any thermoplastic resin may be used. The sealant layer 54 and the sealant layer 57 are formed by film attachment, extrusion processing, coating, etc. When using a varnish or the like that does not adhere to the molding resin as the outermost protective layer 51, a sealant layer 54 can be provided on the outside of the paper layer 55, and the ink layer 52 can be withheld at the welded portion with the resin skeleton 30 (the portion connecting to the resin skeleton 30 is not printed), thereby ensuring sealing with the resin skeleton 30.

[0059] Here, the relationship between the radius of curvature R of the crotch portion 16 and the container blank 10 including the stretched film layer 56 will be described. The inventors of the present invention have prepared a number of samples with different radii of curvature and measured the tear strength of the crotch portion 16, and have grasped the relationship shown in FIG. 5 from the measured data. As shown in FIG. 5, a container blank not including a stretched film layer was prepared, and the tear strength was compared with that of the container blank 10 including the stretched film layer 56 as in the present embodiment. At that time, the radius of curvature R of the crotch portion 16 was changed in a number of stages. As shown in FIG. 5, if the radius of curvature R of the crotch portion 16 is less than 1.0 mm, there is no effect of providing the stretched film layer 56 in terms of tear strength. It has been found that the tear strength can be improved by providing the stretched film layer 56 and setting the radius of curvature R of the crotch portion 16 to 1.0 mm or more.

[0060] According to the container blank 10 of this embodiment, the bottom panel 11 and the side panel 12 include a paper layer 55 and a stretched film layer 56. The radius of curvature R of the crotch portion 16 formed at both ends of the folding line L at the boundary between them is 1.0 mm or more, so that the crotch portion 16 is not easily torn or broken. Therefore, the bottom panel 11 and the side panel 12 can be maintained in an appropriate position relative to the mold. As a result, in the molded container 1, the end faces of the bottom panel 11 and the side panel 12 can be prevented from being exposed. For example, the upper end face 22e (see FIG. 2) of the side portion 22 is covered by at least one of the upper annular portion 33 and the flange portion 36 (i.e., a part of the resin skeleton portion 30). If the end face of any panel is exposed in the container, there is a risk of penetration or leakage of the contents, or the rigidity of the paper being reduced by getting wet when the container is used in a water area, resulting in the physical strength of the container. In the container blank 10 of this embodiment, such an event is prevented.

[0061] According to the container 1 of this embodiment, the end faces of the bottom panel 11 and the side panel 12 are covered by the resin skeleton 30 and are not exposed. This allows the container 1 to have the desired strength. The above-mentioned penetration and leakage of the contents are also prevented.

[0062] The stretched film layer 56 is disposed on the inner side of the paper layer 55. This makes the crotch portion 16 even more resistant to tearing.

[0063] If the stretched film layer 56 has a barrier property, the container 1 produced from the container blank 10 is provided with the barrier property.

[0064] In the container blank 10, the content of the paper layer 55 is 50% by weight or more, thereby reducing the environmental impact.

[0065] (Example) Container blanks 10 having the laminated structures shown in Fig. 6(a) to Fig. 6(e) were produced as Examples 1 to 5, and were evaluated in terms of tensile strength, tear strength, seam appearance, and breakage during molding. In each of the Examples, container blanks similar to that shown in Fig. 3 were produced, and insert molding was carried out to obtain the container shapes shown below. Container base diameter: 55.5mm Container height: 42.5mm Diameter of the opening on the top of the container: 56.0 mm Container taper angle: 1 degree The radius of curvature R of the crotch portion was 3.0 mm in Example 1, 2.0 mm in Example 2, 2.0 mm in Example 3, 2.5 mm in Example 4, and 1.5 mm in Example 5. The ratio of the radius of the bottom panel to the radius of curvature R of the crotch portion was 9.0 in Example 1, 17.5 in Example 2, 17.5 in Example 3, 18.0 in Example 4, and 33.3 in Example 5.

[0066] In Example 1, the paper layer 55 is a double-sided coated paper of 310 g / m 2Polypropylene resin (layer thickness: 18 μm) corresponding to the sealant layer 54 was extruded onto the sheet. A protective layer 51 was formed of OP varnish on the ink layer 52 on the sealant layer 54. Separately, a stretched film (e.g., transparent deposition film: GL-PET, layer thickness: 12 μm) corresponding to the stretched film layer 56 and a CPP (layer thickness: 40 μm) corresponding to the sealant layer 57 were dry laminated together using a two-liquid curing urethane adhesive, and the paper on the side not coated with polypropylene resin and the stretched film surface of the stretched film / CPP film laminate were extruded and laminated with polyethylene resin. After the above-mentioned processed paper was finished, the sheet was cut to the required size and decorated by offset printing. The decorated sheet was punched out using a wooden mold or a metal mold to produce blanks. Then, insert molding was performed.

[0067] In Example 2, the paper layer 55 is a double-sided coated paper of 310 g / m 2 Printing was performed on the surface of the paper (corresponding to ink layer 52), and polypropylene resin was extruded onto it (corresponding to sealant layer 54, layer thickness: 18 μm) to protect the printed surface. Similarly, PET (e.g., Toyobo / E5102, layer thickness: 12 μm) corresponding to oriented film layer 56 was laminated with a CPP film (layer thickness: 40 μm) corresponding to sealant layer 57, and the PET / / CPP laminate was laminated with paper in the same manner as in Example 1 to produce processed paper. Subsequent finishing to obtain the final shape was the same as in Example 1.

[0068] In Example 3, reverse printing was performed on an OPP film (e.g., Toyobo / P6181, layer thickness: 25 μm) corresponding to the stretched film layer 56, and double-sided coated paper 310 g / m corresponding to the paper layer 55 was applied. 2 Then, polypropylene resin was extruded onto the exposed surface of the paper (layer thickness: 40 μm) to create a processed paper. The subsequent finishing to the final shape was the same as in Example 1.

[0069] In Example 4, the double-sided coated paper corresponding to the paper layer 55 is 310 g / m 2A polyethylene resin (layer thickness: 18 μm) corresponding to the sealant layer 54 was extruded onto the surface of the ink layer 52 on the sealant layer 54. A protective layer 51 was formed of OP varnish on the ink layer 52 on the sealant layer 54. Separately, a stretched film (e.g., Toyobo / E5100, layer thickness: 12 μm) corresponding to the stretched film layer 56 and an LDPE film (layer thickness: 50 μm) corresponding to the sealant layer 57 were bonded together by dry lamination using a two-liquid curing urethane adhesive, and the side of the paper not coated with the polyethylene resin and the stretched film surface of the stretched film / LDPE film laminate were bonded together by extrusion processing of the polyethylene resin to produce a processed paper. The subsequent finishing to the final shape was the same as in Example 1.

[0070] In Example 5, the double-sided coated paper corresponding to the paper layer 55 is 310 g / m 2 Printing was performed on the surface of the paper (corresponding to ink layer 52), and polypropylene resin was extruded onto the surface (corresponding to sealant layer 54, layer thickness: 18 μm) to protect the printed surface. As in Example 1, a nylon film (e.g., Unitika / ONBC, layer thickness: 15 μm) corresponding to oriented film layer 56 and an LDPE film (layer thickness: 50 μm) corresponding to sealant layer 57 were laminated together, and polyethylene resin was extruded and laminated to the nylon film surface of the Ny / / LDPE film laminate to produce a processed paper. The subsequent finishing to the final shape was the same as in Example 1.

[0071] (Comparative Example) In addition, as Comparative Examples 1 to 4, container blanks having the laminated structures shown in Figs. 7(a) to 7(d) were prepared, and each was evaluated in terms of tensile strength, tear strength, seam appearance, and breakage during molding. In none of Comparative Examples 1 to 4 was a layer corresponding to the stretched film layer 56 included. The curvature radius R of the crotch portion was 0.9 mm in Comparative Example 1, 3.0 mm in Comparative Example 2, 5.0 mm in Comparative Example 3, and 3.0 mm in Comparative Example 4. The ratio of the radius of the bottom panel to the curvature radius R of the crotch portion was 55.6 in Comparative Example 1, 10.0 in Comparative Example 2, 8.0 in Comparative Example 3, and 9.0 in Comparative Example 4. The container shape by insert molding was the same as in Examples 1 to 5.

[0072] In Comparative Example 1, double-sided coated paper 310 g / m 2 The printing process, blank preparation process, and molding process were the same as in Example 1.

[0073] In Comparative Example 2, double-sided coated paper 310 g / m 2 Polyethylene resin was extruded on both sides of the paper (outer layer thickness: 18 μm, inner layer thickness: 40 μm) to produce a processed paper. The printing process, blank production process, and molding process were the same as in Example 1.

[0074] In Comparative Example 3, double-sided coated paper 310 g / m 2 Printing was performed on the paper, and polypropylene resin (layer thickness: 18 μm) was extruded on top of it to protect the printed surface. A CPP film (layer thickness: 40 μm) was attached to the exposed paper surface to create a processed paper. The printing process, blank preparation process, and molding process were the same as in Example 1.

[0075] In Comparative Example 4, double-sided coated paper 310 g / m 2Polypropylene resin (layer thickness: 18 μm) was extruded into the film. Separately, a stretched film with good hand-tearability (e.g., Toyobo / TF110, layer thickness: 14 μm) and a CPP film (layer thickness: 40 μm) were dry laminated using a two-liquid curing urethane adhesive, and the paper on the side not coated with polypropylene resin and the stretched film surface of the stretched film / CPP laminate were extruded and laminated with polyethylene resin. Since the easy-to-cut stretched film is different from the stretched film layer 56 as explained in the above embodiment, in FIG. 7(d), the reference symbol "56X" is attached to distinguish it from the reference symbol "56" in FIG. 6(a) and the like. That is, the easy-to-cut stretched film 56X is not included in the stretched film layer in this specification. The printing process, blank preparation process, and molding process are the same as those in Example 1.

[0076] In the above-mentioned Examples 1 to 5, no breakage was observed during molding, and there was no problem with the appearance of the seam. In Examples 1 to 5, the tear strength was 30N, 25N, 20N, 32N, and 23N, respectively, which were sufficient values. In Comparative Examples 1 to 4, breakage occurred during molding. Furthermore, in Comparative Example 3, there was a problem with the appearance of the seam. [Explanation of symbols]

[0077] 1...paper-resin composite container, 5...bottom, 6...side, 10...container blank, 11...bottom panel, 12...side panel, 16...(arcuate) crotch portion, 20...three-dimensional blank, 30...resin skeleton, 55...paper layer, 56...stretched film layer, L...fold line, O...center.

Claims

1. a bottom panel corresponding to the bottom of the container; At least one side panel corresponding to a side of the container and connected to a peripheral edge of the bottom panel; the bottom panel and the side panel are integrally formed planar and include a paper layer and a stretched film layer; At both ends of the folding line provided at the boundary between the bottom panel and the side panel, an arc-shaped crotch portion having a center of curvature in an outer area between the bottom panel and the side panel is formed, A container blank, wherein the radius of curvature (R) of the crotch portion is 1.0 mm or more.

2. The container blank according to claim 1 , wherein the stretched film layer is disposed on an inner side of the paper layer.

3. 3. The container blank according to claim 1, wherein the stretched film layer has a barrier property.

4. The container blank according to claim 3 , wherein the stretched film layer is provided with the barrier properties by including a vapor deposition layer.

5. 4. The container blank according to claim 3, wherein the stretched film layer has a coating layer on at least one surface thereof, the coating layer including a barrier coating material consisting of at least one of a barrier resin and a binder resin.

6. 3. A container blank according to claim 1 or 2, wherein the content of the paper layer is 50% by weight or more.

7. A three-dimensional blank obtained by folding the side panel of the container blank according to claim 1 or 2 relative to the bottom panel at the folding line; A paper-resin composite container comprising a resin skeleton portion that extends along the bottom or side panels so as to cover the end surfaces of the bottom panel and the side panels, and is integrated into the three-dimensional blank.

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