JP2009280238A - Paper container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid paper container which is free from container deformation and appearance failure by effectively preventing permeation of moisture through a paper in the processes as of filling the container with a liquid, boiling, and retorting. <P>SOLUTION: The paper container is formed by sticking a sheet of paper and a plastic film together. In order to protect the edge of the paper composing the paper container, the end of the paper is folded so that the edge is between the curling paper portions. Alternatively, a tape is stuck to the end including the edge, thereby preventing the edge from being exposed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to the structure of a container mainly composed of paper for filling and wrapping beverages, etc., and strengthens water resistance at the time of filling and after filling, and is used for paper containers and paper cups for processing of boil sterilization and retort sterilization. This relates to the structure of edge processing.

  Paper containers are widely used mainly for food. In particular, paper containers that store liquids are easier to print directly on the container surface than plastic containers, and the development of recycling systems is progressing, so beverages, seasonings, detergents, pharmaceuticals, industrial chemicals, etc. It is widely used for.

  Among the properties required for these liquid paper containers, the basics are the protection of the contents, and a heat-adhesive resin is applied to the surface of the paper container to prevent the leaching of liquid from the inside and the permeation of gas from the outside. In general, the top and bottom of the container are formed by bending the laminated paper and thermocompression bonding.

  The resistance to water penetration from the surface of the paper that constitutes the paper container can be easily achieved by the lamination of the above-mentioned resin lamination and other barrier layers, but with this alone, water penetration from the paper cut edge (edge) can be achieved. It cannot be prevented. Therefore, one of the problems in the paper container is how to seal the cross section (edge) of the paper.

  In a cylindrical or quadrangular prism-shaped sealed liquid container, the side material constituting the cylinder and the top material constituting the top and the bottom material constituting the bottom are usually thermocompression-bonded by overlapping the joining portions, respectively. The device which prevents the invasion of water is also performed on the end surface including the edge of the paper which is the constituent material of the above. In addition, in the paper cup used in the form that the upper part is opened, a device for preventing the invasion of water is also performed on the end surface including the paper edge of the joint portion with the opening of the top part of the side material and the bottom material of the bottom part. Yes.

  FIG. 1 shows an example of the appearance of a part of a conventional structure of a cylindrical or quadrangular prism-shaped sealed liquid container. FIG. 1 is a schematic cross-sectional view of a joint portion (top caulking portion) between a top material and a side material. It is shown in FIG.

  In FIG. 2, the top material 1 at the top has a structure in which the end surface including the edge is folded upward and is crimped in a form of being wrapped by the end surface of the side material 2 that is folded inside the container (curling). It has become. In the top caulking portion 3, the end portion including the edge of the top material 1 is blocked from outside air by the upper end portion of the side material curled inside the container, but the edge of the side material 2 is exposed to the outside. .

The paper container as shown in FIG. 1 is sealed by heat-sealing a lid (top material) on the upper part after the container is filled with a beverage or the like in the filling process. Thereafter, in the showering process, water is applied to the upper surface of the container, and then water is blown off with compressed air. This step is performed for the purpose of removing the top surface of the container due to “liquid splash” or the like in the filling step.
At this time, if the structure is as shown in FIG. 2, a phenomenon occurs in which water comes into contact with the edge portion of the paper of the side material and enters between the paper layers, resulting in peeling or poor appearance.

FIG. 4 shows an example of the appearance of another part of the conventional structure of a cylindrical or quadrangular prism-shaped sealed liquid container. FIG. 4 is a schematic cross-sectional view of the joint portion (top caulking portion) between the top material and the side material. FIG. 5 shows a diagram, and FIG. 6 shows a schematic cross-sectional view of a joined portion (bottom caulking portion) between a bottom material and a side material at the bottom (bottom). FIG. 7 is a schematic cross-sectional view of an example of a joining portion (side seal) between side members in the case of a conventional cylindrical container, and FIG. 7 shows a joining portion (side seal) between side materials in the case of a square columnar container. A cross-sectional schematic diagram of an example is shown in FIG.

  As in FIG. 2, in FIG. 5, the top material 1 at the top is crimped in a form of being wrapped by the end surface of the side material 2 curled inside the container with the end surface including the edge folded upward. It has a structure. In the top caulking portion 3, the end portion including the edge of the top material 1 is blocked from outside air by the upper end portion of the side material curled inside the container, but the edge of the side material 2 is exposed to the outside. .

  In the case of the bottom caulking portion shown in FIG. 6, as in the case of the top caulking portion in FIG. 5, the bottom material 4 at the bottom portion is curled inside the container with the end face including the edge thereof bent downward. It has a structure in which it is crimped in the form of being wrapped by the end face of the side member 2. In the bottom caulking portion 5, the end portion including the edge of the bottom material 4 is shielded from outside air by the lower end portion of the side material 2 curled inside the container, but the edge of the side material 2 is exposed to the outside. .

  In FIG. 7, the edge protection tape 7 is adhered to the inner end face of the side material 2 at the cylindrical joint portion of the side material 2 to prevent moisture from entering the inside of the side material. The end portion including the other edge of the side member is exposed to the outside. Therefore, in the side material edge processing method with such a structure, the edge protection tape is affixed on the inner side (the part that contacts the content liquid), and the end surface of the paper does not contact the content liquid, but the outer part is external. The edge of the paper is exposed.

  The paper container as shown in FIG. 4 is filled with the content liquid, sealed, and then boiled or retorted (pressurized and heated), so that water penetrates the paper from the part where the end face of the paper is exposed on the outer surface. However, the paper is soft and it is difficult to maintain its shape, which causes problems in appearance.

  Next, a conventional product of a paper cup used with the upper part opened will be described. An example of the appearance of a part of the conventional structure of a paper cup is shown in FIG. 12, a schematic cross-sectional view of a side material entrapping portion (top curl portion) corresponding to a top (top) drinking mouth is shown in FIG. FIG. 14 is a schematic cross-sectional view of the bottom caulking portion. FIG. 13 shows a state in which the upper part of the side material 2 is curled outward to form a drinking mouth, and the top curl portion 8 is in the state of being wound around the outer side in this case (Patent Document 1). ).

  As described above, the top portion is curled one or more times, and the edge portion of the side member 2 appears inside the closed space formed in the top curl portion by entrainment, so that it seems to be blocked from the outside air. If the end of the side material 2 is not heat-pressed, the edge of the paper tends to communicate with the outside. Also in the case of the bottom caulking portion 5 shown in FIG. 14, the bottom material 4 at the bottom portion is wrapped in the end surface of the side material 2 curled inside the container with the end surface including the edge bent downward. The structure is crimped (Patent Documents 2 and 3). In the bottom caulking portion 5, the end portion including the edge of the bottom material 4 is shielded from outside air by the lower end portion of the side material 2 curled inside the container, but the edge of the side material 2 is exposed to the outside. (Patent Document 4).

  In FIG. 15, the edge protection tape 7 is stuck to the inner end face of the side material 2 at the cylindrical joining portion of the side material 2, and prevents moisture from entering the inside of the side material. The end portion including the other edge of the side member is exposed to the outside.

  Therefore, in the side material edge processing method with such a structure, the edge protection tape is affixed on the inner side (the part that contacts the content liquid), and the end surface of the paper does not contact the content liquid, but the outer part is external. The edge of the paper is exposed. The same applies to the skive hemming process.

As described above, in the conventional paper cup edge processing method, water permeates into the paper from the portion where the end surface of the paper is exposed on the outer surface, and the paper becomes dull and it is difficult to maintain the shape, resulting in defects in appearance. was there.
JP 2004-291666 A JP 2003-31653 A JP 2002-68163 A Japanese Patent Laid-Open No. 2000-211174

  It is an object of the present invention to provide a liquid paper container that can effectively prevent moisture from penetrating into the paper in a liquid filling process, a boil processing process, a retort processing process, etc., and does not cause deformation or appearance failure of the container. And

  The invention of claim 1 is a paper container composed of a sheet in which paper and a plastic film are bonded together, and in order to protect the edge of the paper constituting the paper container, the edge is folded back and the edge is wound between the paper. Alternatively, the paper container is characterized in that the edge is not exposed to the outside by sticking a tape to an end including the edge.

  The invention of claim 2 is a container having a top material, a side material, and a bottom material, which is molded into a cylindrical or quadrangular prism shape, and when forming a portion for adhering the side material and the top material, the top of the side material The step of curling the side end portion toward the inside of the container has a structure in which the edge of the side material end portion is not exposed to the outside of the container by curling the side material end portion one or more times. It is a paper container.

  The invention of claim 3 is a container having a top material, a side material, and a bottom material, and formed into a columnar or quadrangular prism shape, and forming a portion for adhering the side material and the top material and the side material and the bottom material. In addition, in the step of curling the top and bottom ends of the side material to the inside of the container, the edge of the side material end is not exposed to the outside of the container by curling the side material end more than once. The paper container according to claim 1.

  The invention according to claim 4 is a container having a top material, a side material, and a bottom material, which is molded into a columnar shape or a quadrangular prism shape, and the edge of the side material ends at the inside of the container at the portion where the side materials are bonded together 4. The structure according to claim 3, wherein both end portions facing the outer side are bonded to each other with a tape-like film so that the edge of the end portion of the side material is not exposed to the inner side and the outer side of the container. Paper container.

  The invention of claim 5 is a container having a side material and a bottom material and molded into a cup shape. In the step of curling the top side end of the side material outward, the end of the side material is curled one or more times. 2. The paper container according to claim 1, wherein the paper container is formed into a flange shape by performing thermocompression bonding or ultrasonic pressure, so that the paper edge of the side material top side end surface is not exposed to the outside. is there.

The invention of claim 6 is a container having a side material and a bottom material and molded into a cup shape,
When forming the part that bonds the side material and the bottom material, in the step of curling the bottom side end of the side material to the inside of the container, the side material bottom side end surface is curled by one or more rounds of the side material end. The paper container according to claim 5, wherein the paper edge is configured not to be exposed to the outside.

  The invention of claim 7 is a container having a side material and a bottom material and molded into a cup shape, and the edge of the side material end faces both the inside and the outside of the container at the portion where the side materials are bonded together. 7. The structure according to claim 5 or 6, wherein the end portion of the side member is structured such that the edge of the end portion of the side material is not exposed to the inside and outside of the container by bonding a tape-like film or skive hemming. It is a paper container of description.

  Here, one side of the end of the side material is previously removed from the tip by a predetermined length, half of the thickness of the side material is deleted (skive), and the remaining portion is turned back so that the deleted surface is on the inside (hemming) The process for protecting the edge of the end face of the side material is called a skive hemming process.

  According to the paper container of the present invention, in the curling process of the top portion of the side material of the container having a top material, a side material, and a bottom material, and molded into a columnar or quadrangular prism shape, by winding the side material one or more times, By adopting a structure in which the end face of the paper on the side of the top side of the side material is not exposed to the outside, the paper will not peel off even if water is applied by showering after filling the contents.

  According to the paper container of the present invention, in the curling process of the top part and the bottom part of the side material, the edges of the paper on the side material top side and the bottom side end part are not exposed to the outside by winding the side material one or more times. It can be a structure.

  According to the paper container of the present invention, the edge protection tape is applied to both the inner side (the part that comes into contact with the content liquid) and the outer side (the part that is exposed to the outside) of the side material end of the side seal part. The end face of the paper does not come into contact with the content liquid or the outside.

  In the paper container of the present invention, since the paper is not directly exposed on both the inner surface side and the outer surface side, strength deterioration and poor appearance due to moisture penetrating into the paper can be prevented in boil processing and retort processing.

  In the paper cup of the present invention, in the curling process of the bottom part of the side material of the container that has the side material and the bottom material and is molded into a cup shape, the end of the side material is curled one or more times, and then thermocompression bonding (or super-compression) By sonic bonding, the edge of the paper is not exposed to the outside. Edge protection tape is affixed to both the inside (part that contacts the content liquid) and the outside (part exposed to the outside) of the edge of the side material, so that the end face of the paper does not contact the content liquid or the outside. It has a structure. Since the paper is not directly exposed on both the inner surface side and the outer surface side, it is possible to prevent strength deterioration and appearance defects due to moisture penetrating into the paper.

  Hereinafter, as an embodiment of the present invention, an example in which the content is a beverage will be described with reference to the drawings. For convenience of explanation, the case of a sealed liquid container and a paper cup will be described separately. Moreover, the same code | symbol may be used about what has the same function.

FIG. 1 is an external view showing an example of an external appearance of a sealed paper container of the present invention, and shows a case where (a) is a columnar shape and a case (b) is a quadrangular prism shape. In addition, FIG. 1 is a general conceptual diagram and shares the same figure as the example of the external appearance of the conventional sealed paper container. FIG. 3 is a schematic cross-sectional view of an example of the top caulking portion of the sealed paper container of the present invention. Compared with the case of the conventional sealed paper container (FIG. 2), in the top caulking portion 3 of the conventional sealed paper container, the upper end portion of the side material 2 is folded inward, but the upper end portion The edge is fixed at a position where it touches the outside air. On the other hand, in the case of the sealed paper container of the present invention (FIG. 3), the upper end of the side member 2 is folded inward one or more times in the top caulking portion 3 so that the edge of the upper end is the top. It exists in the closed space enclosed with the side material 2 and the top material 1 with the edge of the edge part of the material 1, and the contact with external air is interrupted | blocked.

  FIG. 4 is an external view showing another example of the external appearance of the sealed paper container of the present invention, and shows a case where (a) is a columnar shape and a case (b) is a quadrangular prism shape. FIG. 4 is a general conceptual diagram and shares the same view as an example of the appearance of a conventional sealed paper container.

  FIG. 9 is a schematic cross-sectional view of an example of a top caulking portion and a bottom caulking portion of the sealed paper container of the present invention. In FIG. 9, the top caulking portion and the bottom caulking portion are described in the same diagram for the sake of simplicity. Compared with the case of the conventional sealed paper container (FIG. 5), in the top caulking portion 3 of the conventional sealed paper container, the upper end portion of the side member 2 is folded inward, but the upper end portion The edge is fixed at a position where it touches the outside air. Similarly, compared with the case of the conventional sealed paper container (FIG. 6), in the conventional bottom caulking portion 5, the lower end portion of the side member 2 is folded inward, but the edge of the lower end portion touches the outside air. Fixed in position.

  On the other hand, in the case of the sealed paper container of the present invention (FIG. 9), since the upper end portion of the side member 2 is folded inward one or more times in the top caulking portion 3, the edge of the upper end portion is the top. It exists in the closed space enclosed with the side material 2 and the top material 1 with the edge of the edge part of the material 1, and the contact with external air is interrupted | blocked. Similarly, in the case of the sealed paper container of the present invention (FIG. 9), the bottom caulking portion 5 is in a state where the lower end portion of the side member 2 is folded inward one or more times, so that the edge of the upper end portion of the bottom member 4 It is in the closed space enclosed by the side material 2 and the bottom material 4 with the edge of the edge part, and the contact with external air is interrupted | blocked.

  FIG. 10 is a schematic cross-sectional view of an example of a side seal portion of a sealed paper container (cylindrical shape) of the present invention, and FIG. 11 is an example of a side seal portion of a sealed paper container (square column shape) of the present invention. It is a cross-sectional schematic diagram. FIG. 7 is a schematic cross-sectional view of an example of a side seal portion of a conventional sealed paper container (cylindrical shape), and FIG. 8 is a schematic cross-sectional view of an example of a side seal portion of a conventional sealed paper container (square column shape). FIG.

  In the side seal portion of the conventional sealed paper container shown in FIGS. 7 and 8, the end portion including the edge at the inner position of the side member 2 is covered with the edge protection tape 7, but the edge at the outer position. The end portion including is open to the outside air.

  On the other hand, in the case of the sealed paper container of the present invention (FIGS. 10 and 11), both the edge part including the edge at the inner position and the edge part including the edge at the outer position of the side member 2 are edge protection tapes. 7, the edge of the side material is not open to the outside air.

The sealed paper container of the present invention has a top material, a side material, and a bottom material, and is a container molded into a cylinder or a quadrangular prism shape, and has a portion that bonds the side material and the top material and the side material and the bottom material. A structure in which the edge of the side material end is not exposed to the outside of the container by curling the side material end part one or more times in the step of curling the top side and bottom side end parts of the side material inside the container when forming. In order to prevent water from entering through the edge of the side material end face from the outside, both ends of the side material end facing the inside and outside of the container are tape-shaped. The paper container has a structure in which the edge of the side member is not exposed to the inside and the outside of the container by bonding films or skive hemming.

  The method for forming this sealed container is to first print a printed side material blank by attaching edge protection tape so that the edge of the side material end covers both ends facing the inside and outside of the container. To form a side wall member. The bottom material is wound into a substantially circular bottom member shape and drawn into a shape in which the outer peripheral edge stands downward. The top material is wound by punching the mouth portion, punching out into a substantially circular lid member shape having the same size as the bottom member, and drawing into a shape in which the outer peripheral edge portion stands upward.

  Next, the outer surface of the bottom member having a substantially circular shape with the outer peripheral edge standing downward is joined to the lower inner surface of the cylindrical side wall member, and the lower end edge of the side wall member is inward so as to cover the outer peripheral portion. One or more rounds are bent, and the bottom member is attached to the lower surface of the side wall member by pressure bonding to the inner surface of the outer peripheral edge of the bottom member by knurling.

  At that time, hot air is blown to the lower inner surface of the cylindrical side wall member and the outer surface of the outer peripheral edge portion of the bottom member to soften the heat-adhesive resin of the inner side layer of the side wall member, and heat bonding of the outer layer of the outer peripheral edge portion of the bottom member Each of the functional resins is softened, and the inner layer surface of the side wall member bent inward one or more times and the outer layer surface of the outer peripheral edge portion of the bottom member are joined by thermocompression bonding.

  Similarly, the upper surface of the side wall member is inwardly joined to the upper inner surface of the cylindrical side wall member so that the outer surface of the lid member having a substantially circular shape with the outer peripheral edge rising upward is joined. One or more rounds are bent, and the cover member is pressure-bonded to the inner surface of the outer peripheral edge portion of the lid member by knurling, and the lid member is attached to the upper portion of the side wall member.

  At that time, hot air is blown to the upper inner surface of the cylindrical side wall member and the outer surface of the outer peripheral edge portion of the lid member to soften the heat-adhesive resin of the inner side layer of the side wall member, and thermal bonding of the outer layer of the outer peripheral edge portion of the lid member Each of the functional resins is softened, and the inner layer surface of the side wall member bent inward one or more times and the outer layer surface of the outer peripheral edge portion of the lid member are bonded by thermocompression bonding.

  In this way, the paper cylindrical container having the bottom member and the lid member attached to both ends of the side wall member is finally filled with the content liquid such as juice from the drinking mouth portion, and the content mouth liquid is sealed with a tab material. It becomes a paper cylindrical container filled with. When molding the printed side material blank into a cylindrical side wall member, instead of attaching edge protection tape so that the edge of the side material end covers both ends facing the inside and outside of the container, Alternatively, the edge of the side member may be preliminarily prevented from being exposed by skive hemming.

  As the material used for the sealed paper container of the present invention, the same basic structure is used for the side material, the bottom material, and the top material. An essential component is a laminated sheet in which paper and plastic are bonded together. Usually, printing for displaying contents and a barrier layer for protecting contents are used in combination.

  FIG. 19 shows a schematic cross-sectional view of an example of the layer configuration of the laminated sheet used in the paper container of the present invention. A printing layer 13 such as characters and patterns is applied to the front side of the container 10 of the paper 10 that is the main body of the container base, and a barrier film 14 for protecting the contents is provided on the inner side of the container. The layers of thermal adhesive resins 11 and 12 are provided on the outermost surface and the innermost surface.

The paper base material shown by the paper 10 is not particularly limited, but has a basis weight of about 150 to 500 g / m ^{2 of} bleached kraft paper having printability and paper strength, excellent formability and strong surface strength. Is used. A normal printing method such as a gravure printing method or an offset printing method is used for the printing layer 13, and a known ink can be used as the ink.

  As the heat-adhesive resins 11 and 12, resins having heat sealing properties, for example, polyolefin resins such as polyethylene and polypropylene are usually used. A typical example is a low-density polyethylene resin, but when the heat resistance of the inner resin layer of the container at the time of sealing is required, a high melting point resin such as a polypropylene resin can be used in combination. The film thickness of the heat-adhesive resins 11 and 12 is usually 10 to 50 μm and is generally provided by hot melt extrusion such as an extruder.

  Among the layer components of the laminated sheet used in the paper container of the present invention, the barrier film 14 is a film for preventing permeation of oxygen, steam, etc. for protecting contents, and is a plastic on which aluminum foil or an inorganic compound is deposited. Film etc. are used.

  Aluminum foil is used when a high level of barrier properties is required, and plastic films on which inorganic compounds are deposited are used when contacting with the contents. Absent. However, a high gas barrier packaging material containing metal foil exhibits excellent gas barrier properties regardless of the environment such as temperature and humidity, but the package formed using this packaging material does not contain the contents. It is necessary to consider that it is unsuitable for microwave heating because it has disadvantages such as being invisible, having to be handled as non-combustible material at the time of disposal, and being unable to use a metal detector for foreign object inspection after contents are put in. There is. In this case, the thickness of the aluminum foil may be in the range of 10 to 50 μm. If it is thinner than this, the possibility of appearance of pinholes is large, and if it is thicker than this, there is a problem in workability.

  FIG. 20 shows a schematic cross-sectional view of an example of a layer structure of a plastic film on which an inorganic compound is deposited. A primer layer 16 is provided on at least one surface of a plastic film 15 as a substrate. And the inorganic oxide vapor deposition layer 17 and the gas barrier layer 18 are laminated | stacked in order on the surface.

  Examples of the plastic film 15 as the base material include polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyolefin films such as polyethylene and polypropylene, polystyrene films, polyamide films, polyvinyl chloride films, polycarbonate films, polyacrylonitrile films, A biodegradable plastic film such as a polyimide film or a polylactic acid film is used, and it may be either stretched or unstretched, and preferably has mechanical strength and dimensional stability. In particular, polyethylene terephthalate stretched biaxially from the viewpoint of heat resistance or the like is preferably used.

  In addition, various known additives and stabilizers such as antistatic agents, ultraviolet inhibitors, plasticizers, lubricants, etc. may be used on the surface of the plastic film 15 to improve the adhesion to the thin film. In addition, corona treatment, low temperature plasma treatment, ion bombardment treatment may be performed as pretreatment, and chemical treatment, solvent treatment, etc. may be performed.

  The thickness of the plastic film 15 is 1 μm or more, suitability as a packaging material, there are cases where other layers are laminated, and processing when forming a vapor-deposited thin film layer 4 and a gas barrier coating layer 5 made of an inorganic oxide. In consideration of the properties and the like, it can be practically selected in the range of 3 to 200 μm, but in many applications, it is preferably 6 to 30 μm.

In order to improve adhesion between the plastic film 15 and the inorganic oxide vapor deposition layer 17, a primer layer 3 made of a composite containing a polyol resin, an isocyanate compound, and a silane coupling agent may be provided. The primer layer 3 is also a layer for improving adhesion between the plastic film 15 and the inorganic oxide vapor deposition layer 17 and preventing the vapor deposition layer from peeling off during storage of liquid contents or storage in a high temperature environment. What can be used as a primer layer is selected from general polymer resins used as adhesives such as polyurethane resins, polyester resins, acrylic resins, and ether resins.

  The thickness of the primer layer is not particularly limited as long as a uniform coating film can be formed, but the dry film thickness is generally preferably in the range of 0.01 to 2 μm. When the dry film thickness is thinner than 0.01 μm, it is difficult to obtain a uniform coating film, and the adhesion may be lowered. On the other hand, when the dry film thickness exceeds 2 μm, the coating film cannot be kept flexible because it is thick, and there is a possibility that the coating film may crack due to external factors, which is not preferable.

  As a method for forming the primer layer, for example, a known printing method such as an offset printing method, a gravure printing method, a silk screen printing method, or a known coating method such as a roll coating method, a knife edge coating method, or a gravure coating method may be used. Can do. As for the drying conditions, appropriate conditions are adopted within the range of generally used conditions.

  The inorganic oxide vapor-deposited layer 17 is made of a vapor-deposited film of an inorganic oxide such as aluminum oxide, silicon oxide, tin oxide, magnesium oxide, or a mixture thereof, as long as it has gas barrier properties such as oxygen and water vapor. Among these, aluminum oxide, silicon oxide, and magnesium oxide are particularly preferable because they are excellent in terms of low oxygen permeability and water vapor permeability.

  The optimum thickness of the inorganic oxide deposition layer 17 varies depending on the type and configuration of the inorganic compound used, but is generally preferably in the range of 5 to 300 nm, and is appropriately selected within that range. However, if the film thickness is less than 5 nm, a uniform film may not be obtained or the film thickness may not be sufficient, and the function as a gas barrier material may not be sufficiently achieved. On the other hand, when the film thickness exceeds 300 nm, flexibility cannot be maintained in the thin film, and the thin film may be cracked due to external factors such as bending and pulling after the film formation. Preferably, it exists in the range of 5-100 nm.

  There are various methods for forming the inorganic oxide vapor deposition layer 17 on the primer layer 16, and it can be formed by a normal vacuum vapor deposition method, but other thin film formation methods such as sputtering, ion plating, and plasma. A vapor deposition method or the like can also be used. However, considering productivity, the vacuum deposition method is the best at present. Electron beam heating, resistance heating, induction heating, etc. are preferred as the heating means of the vacuum deposition apparatus by vacuum deposition, and plasma assist is used to improve the adhesion between the deposited thin film layer and the substrate and the denseness of the thin film. It is also possible to use an ion beam assist method.

  The gas barrier layer 18 is provided in order to provide a high level of gas barrier property similar to that of a metal foil and to physically protect the inorganic oxide vapor deposition layer 17.

For example, the gas barrier layer 18 includes Si (OR ¹ ) ₄ and R ² Si (OR ³ ) ₃ (R ¹ and R ³ are hydrolyzable groups such as CH ₃ , C ₂ H ₅ , C ₂ H ₄ OCH ₃ , R ² is a layer formed by applying a solution in which a silicon compound represented by an organic functional group) or a hydrolyzate thereof and a water-soluble polymer having a hydroxyl group are mixed and dried by heating.

Of the coating liquid components used to form the gas barrier layer 18, the silicon compound R ² Si (OR ³ ) ₃ is R ³ is a hydrolyzable group such as CH ₃ , C ₂ H ₅ , C ₂ H ₄ OCH ₃ , R ² is an organic functional group, and is generally used as a silane coupling agent to improve the adhesion between the organic compound layer and the inorganic compound layer.

Even in the case of the laminated sheet used in the paper container of the present invention, it is necessary for improving the adhesion between the inorganic oxide vapor deposition layer and the gas barrier layer. Among them, those having a non-aqueous functional group such as a vinyl group, an epoxy group, a ureido group, and an isocyanate group as the organic functional group (R ² ) are non-aqueous and have high resistance to hot water, and the isocyanate group is polymerized. Isocyanurate is particularly preferred because it is easy to handle in the coating liquid, slows the gelation of the coating liquid, and can improve adhesion without causing a decrease in barrier properties due to the addition of a silane coupling agent. .

  Among the coating liquid components used to create the gas barrier layer 18, examples of the water-soluble polymer having a hydroxyl group include polyvinyl alcohol, starch, and celluloses. In particular, when polyvinyl alcohol (hereinafter referred to as PVA) is used as a coating agent, the gas barrier property is most excellent.

  In consideration of adhesion to ink, adhesive, wettability, and prevention of cracking due to shrinkage to the coating liquid, isocyanate compounds, clay minerals such as colloidal silica and smectite, stabilizers, colorants, viscosity modifiers Known additives such as can be added within a range that does not impair gas barrier properties and water resistance.

  The thickness of the gas barrier layer 18 after drying is not particularly limited. However, if the dry film thickness is less than 0.01 μm, it is difficult to obtain a uniform film. If the dry film thickness exceeds 50 μm, cracks may easily occur. Therefore, it is desirable that the thickness be 0.01 to 50 μm.

  As a method for forming the gas barrier layer, a normal coating method can be used. For example, dipping, roll coating, gravure coating, air knife coating, comma coating, die coating, screen printing, spray coating, gravure offset, and the like can be used. It applies | coats on an inorganic oxide vapor deposition layer using these coating systems. As the drying method, any of these methods may be used as long as the gas barrier layer is heated such as hot air drying, hot roll drying, high frequency irradiation, infrared irradiation, etc., and water is removed, and two or more of these may be combined.

  The layer structure of the tape-like film (edge protection tape) for bonding the left and right ends of the side material at the part where the side materials are used together for the paper container of the present invention is thermally bonded to the barrier film. The constituent elements of the heat-resistant resin and the barrier film are the same as those used for the side material, the top material, and the bottom material of the paper container, and the description thereof is omitted here. However, since the use of an aluminum foil is not preferred for the barrier film because it is also used for the portion of the contents in contact with the liquid, an oriented compound vapor deposition film is desirable.

  Next, among the paper containers of the present invention, a container (paper cup) having a side material and a bottom material and molded into a cup shape will be described.

  The paper cup of the present invention is composed of a laminated sheet provided with a thermoplastic resin layer on at least one side of a cup base paper, and has a body part and a bottom part, and has a mouth part whose opening periphery is curled outwardly. And a paper cup in which an annular leg is formed at the joint of the bottom.

  FIG. 12 is an external view showing an example of the appearance of a paper container molded into a cup shape of the present invention. FIG. 12 is a general conceptual diagram and shares the same view as an example of a conventional appearance of a paper container molded into a cup shape. 16 is a schematic cross-sectional view of an example of the top curl portion of the paper container (paper cup) of the present invention, FIG. 17 is a schematic cross-sectional view of an example of the bottom caulking portion of the paper container (paper cup) of the present invention, and FIG. It is a cross-sectional schematic diagram of an example of the side seal part of the paper container (paper cup) of this invention.

  In the conventional case (FIG. 13), the top curl of the paper container (paper cup) of FIG. 16 is curled one or more times, and the edge portion of the side material 2 is closed to be formed on the top curl by winding. Although it seems to be shielded from the outside air by being present in the space, if the end of the side member 2 is not heat-bonded, the edge of the paper tends to communicate with the outside air. On the other hand, in the case of the paper cup of the present invention shown in FIG. 16, after the edge portion of the side material 2 is wound one or more times, the side materials wound by thermocompression bonding, ultrasonic pressure bonding, or the like are pressure bonded. This prevents the edge from communicating with the outside air. Since FIG. 17 and FIG. 18 are the same as in the case of an airtight container, description thereof is omitted.

  In general, a paper cup is a cylinder member that is a cylindrical body member that tapers downward by joining one end of a fan-shaped body member (side material) to the other end and joining them together. Forming step, bottom member forming step that squeezes the bottom paper punched out from the roll for the bottom member (bottom material) into a substantially circular shape and raises the outer peripheral edge downward to make the bottom member a bottom member on the lower inner surface of the body member The inner surface of the outer peripheral edge of the bottom member is joined, and the lower end edge of the body member is folded inward so as to cover the outer peripheral edge, and hot air, heat pressure or ultrasonic waves are applied to the outer surface of the outer peripheral edge of the bottom member. It is produced through each step of a leg portion forming step for forming an annular leg portion by joining, etc., and finally a rim portion forming step for winding the upper peripheral edge of the trunk member outward and forming a lip portion. Yes.

  The paper cup characterized in that the paper edge of the side material top side end surface of the present invention is not exposed to the outside can be manufactured as follows, for example, in the above-mentioned lip forming step.

  That is, the top of the paper cup that forms the top curl portion by winding it while guiding the periphery of the upper end opening of the paper cup to which the body portion and the bottom portion are joined along the curved groove portion provided on the curl mold. In the curl forming process, the curved groove portion is composed of a first curl portion and a second curl portion, the first curl portion pre-curls outward with respect to the periphery of the upper end opening of the paper cup, and then the second curl portion opens. Winding up the edge of the paper cup while guiding the periphery along the curved groove part and raising the bottom part of the paper cup at the same time, further winding up the opening edge part along the curved groove part of the second curl part, winding more than one turn After molding a paper cup with a top curl part, the top curl part of the paper cup has a temperature higher than the melting point of the innermost layer resin applied to the inner surface of the paper cup. Wind was blowing heated from the hot air insertion part of the hot air device, by cooling, it is possible to not expose the structure of the paper edge of the top curl portion to the outside.

The laminated sheet used in the paper cup of the present invention is composed of a polypropylene resin, low density on both sides or one side of a base paper of the cup having a basis weight of about 100 to 500 g / m ² , both of the trunk member forming the trunk and the bottom member forming the bottom. It is a generally known laminated sheet in which a polyolefin resin such as polyethylene resin is applied to about 10 to 50 μm to form a heat-adhesive resin layer. In particular, the cup base paper used for the body portion is required to have a paper strength (strength) that does not cause cracking even when the top curl portion is stretched by applying a large pulling force. Furthermore, since the surface is subjected to printing processing, it is required to be excellent in printing suitability. In particular, the smoothness or cushioning property or rigidity of the paper base material and appropriate water absorption are important in relation to the acceptability of ink in printing and the glossiness of printing.

The paper base material used for the body member and the bottom member of the paper cup is not particularly limited, but the cup base paper having printability and paper strength, excellent formability, and strong surface strength as described above is mainly used. It is done. The base paper of the paper base is made with bleached kraft pulp using a long paper machine or a paper machine using a circular or short mesh. Further, a cup base paper impregnated with an aqueous binder solution such as starch in a size press process and further subjected to calendar press processing or the like to improve surface properties, excellent printability, and water resistance is produced.

Also, the cup base paper paper base used in the body member varies depending on the content or the like to the size or application or storage of the paper cup, a basis weight of from 190 g / m ² in the range of 450 g / m ² cups Base paper is used. The thickness of the paper is preferably in the range of 200 μ to 400 μ. Further, by adding an anti-blocking agent, a slip agent or the like to the thermoplastic resin used for the innermost layer of the surface and the inner surface, the slipperiness in the paper cup molding machine is improved.

  Further, the melting point of the resin of the heat-adhesive resin layer on the surface of the cup is 100 ° C. to 145 ° C., and the resin of the innermost layer of the heat-adhesive resin layer is the same as the surface or 115 ° C. having a higher melting point than the surface. It may be in the range of ˜155 ° C. In addition, the thickness of the heat-adhesive resin layer used for the innermost layer on the surface and the inner surface varies depending on the size of the paper cup or the intended use or the contents to be stored. The thickness of the layer is 15 μ to 50 μ, and the thickness of the heat-adhesive resin layer used as the innermost layer on the inner surface is about 15 μ to 50 μ. Further, the heat-adhesive resin used in the present invention is typically polyethylene (PE) or polypropylene (PP). The thermoadhesive resin layer used for the innermost layer is provided with a thickness of about 15 to 50 μm. As other films, polyethylene terephthalate (PET), polymethylpentene (PMP), ethylene / vinyl acetate copolymer (EVAC) or the like is often used for the purpose of imparting processability and barrier properties.

  These resins are bonded to the surface or the inner surface of the paper base material by a method such as extrusion coating processing by applying heat-melting or laminating processing to form a film. In addition, depending on the size of the paper cup or the use or contents to be stored, a multilayer film such as polyethylene / polymethylpentene / polyethylene or polyethylene / ethylene / vinyl acetate copolymer / polyethylene, polyethylene / aluminum / polyethylene or polyethylene / polyethylene terephthalate is used on the inner surface. Can be used by being bonded to a paper substrate. As previously mentioned in the configuration of the laminate used in the sealed paper container, the film laminated on the cup base paper should be treated with a barrier coating such as a vapor deposition coating of an inorganic compound or a barrier aqueous coating. Is also possible.

Next, the base paper of the paper base used for the bottom member of the paper cup of the present invention may be basically the same as the paper base used for the barrel member, and the basis weight is 150 g / m ^{2 to} 370 g / m. A range of ² is preferred. Other specifications as the laminated body can use the same means as the body member.

  Specific examples of the present invention will be described below.

<Example 1>
As the plastic film 15, a biaxially stretched polyethylene terephthalate film having a thickness of 12 μm was used. The following primer solution was applied and dried on one side by gravure coating to form a primer layer 16 having a thickness of 0.1 μm. A vapor deposition layer made of aluminum oxide having a thickness of 15 nm was laminated on the primer layer 16 by a vacuum vapor deposition apparatus using an electron beam heating method. Next, the following gas barrier layer coating solution was applied by a gravure coating method, and then dried at 120 ° C. for 2 minutes to form a gas barrier layer 18 having a thickness of 0.5 μm, whereby a barrier film 14 was obtained.

(Primer solution)
In a diluting solvent (ethyl acetate), 10 parts by weight of acrylic polyol was mixed with 1 part by weight of γ-isocyanatopropyltrimethylsilane and stirred. Next, a mixture of XDI and IPDI in a weight ratio of 7 to 3 was added as an isocyanate compound so that the isocyanate groups of this isocyanate compound were equivalent to the hydroxyl groups of the acrylic polyol. A solution obtained by diluting this mixed solution to 2% by weight as the concentration of the added compound was used as a primer solution.

(Gas barrier layer coating solution)
(A) Hydrolysis solution obtained by adding 70 g of hydrochloric acid (0.1N) to 20 g of tetraethoxysilane (Si (OC ₂ H ₅ ) ₄ ; hereinafter referred to as TEOS) and 10 g of methanol, followed by hydrolysis for 30 minutes. (B) 5% of polyvinyl alcohol, water / methanol = 95/5 aqueous solution.
(C) Hydrolysis solution prepared by adjusting 1,3,5-tris (3-trialkoxysilylalkyl) isocyanurate with water / IPA = 1/1 solution.

  A liquid, B liquid, and C liquid were mixed in the ratio of A / B / C = 70/20/10 (weight%), and the coating liquid of the gas barrier layer was obtained.

The barrier film 14 obtained as described above is dry laminated on the opposite surface of the bleached kraft paper 10 having a basis weight of 250 g / m ² provided with the printing layer 13 and the printing layer 13, and then the laminated sheet is formed. Dry lamination was performed so as to be sandwiched between two pieces of linear low-density polyethylene (LLDPE) film 7 having a thickness of 40 μm to obtain a laminated sheet for a side material. A laminated sheet for the top material and a laminated sheet for the bottom material were obtained in the same manner as described above except that the printing layer 13 was not provided.

  Using these three types of laminated sheets, the sealed container of the present invention was molded.

  First, a blank obtained by punching the printed side material is bonded to an edge protection tape so that the edge of the side material end covers both ends facing the inside and outside of the container (FIG. 10). Molded into a side wall member. The bottom material was wound into a substantially circular bottom member shape, and drawn into a shape in which the outer peripheral edge stood downward (FIG. 9). For winding the top material, the mouthpiece 9 is perforated and punched into a substantially circular lid member shape having the same size as the bottom member, and drawn into a shape in which the outer peripheral edge stands up (FIG. 9). .

  Next, the outer surface of the bottom member having a substantially circular shape with the outer peripheral edge standing downward is joined to the lower inner surface of the cylindrical side wall member, and the lower end edge of the side wall member is inward so as to cover the outer peripheral portion. One or more rounds were bent, and the bottom member was attached to the inner surface of the outer peripheral edge of the bottom member by knurling and attached to the bottom of the side wall member (top crimping portion 3 or bottom crimping portion 5 in FIG. 9).

  At that time, hot air is blown to the lower inner surface of the cylindrical side wall member and the outer surface of the outer peripheral edge portion of the bottom member to soften the heat-adhesive resin of the inner side layer of the side wall member, and heat bonding of the outer layer of the outer peripheral edge portion of the bottom member Each of the functional resins was softened, and the inner layer surface of the side wall member bent inward one or more times and the outer layer surface of the outer peripheral edge portion of the bottom member were joined by thermocompression bonding.

  Similarly, the upper surface of the side wall member is inwardly joined to the upper inner surface of the cylindrical side wall member so that the outer surface of the lid member having a substantially circular shape with the outer peripheral edge rising upward is joined. One or more rounds were bent, and knurled to the inner surface of the outer peripheral edge of the lid member, and attached to the upper part of the side wall member of the lid member.

  At that time, hot air is blown to the upper inner surface of the cylindrical side wall member and the outer surface of the outer peripheral edge portion of the lid member to soften the heat-adhesive resin of the inner side layer of the side wall member, and thermal bonding of the outer layer of the outer peripheral edge portion of the lid member Each soft resin was softened, and the inner layer surface of the side wall member bent inward one or more times and the outer layer surface of the outer peripheral edge portion of the lid member were joined by thermocompression bonding.

  In this way, the paper cylindrical container having the bottom member and the lid member attached to both ends of the side wall member is finally filled with content liquid such as juice from the drinking mouth portion 9, and the drinking mouth portion is covered with a tab material (not shown). A paper container filled with the content liquid was prepared by heat sealing.

<Example 2>
When the printed side material blank is formed into a cylindrical side wall member, instead of pasting edge protection tape, the edge of the side material is processed in advance to prevent edge exposure by skive hemming. A paper container filled with the contents was prepared in the same manner as in Example 1.

<Example 3>
The barrier film 14 obtained in the same manner as in Example 1 was dry-laminated on the opposite side of the base paper 10 and the printed layer 13 having a basis weight of 225 g / m ² provided with the printed layer 13, and then the laminated sheet. Was laminated between two pieces of linear low-density polyethylene (LLDPE) film 7 having a thickness of 40 μm, and an extruder laminate was performed to obtain a laminated sheet for a side material. A laminated sheet for bottom material was obtained in the same manner as described above except that the printing layer 13 was not provided.

  A blank obtained by punching a printed laminated sheet for side material into a fan shape, and applying edge protection tape so that the edge of the side material edge covers both ends facing the inside and outside of the container (FIG. 18) In addition, it was formed into a cylindrical body member that tapers downward. Furthermore, the bottom paper punched out in a substantially circular shape from the roll of the bottom sheet laminated sheet is squeezed to make the outer peripheral edge stand downward to form the bottom member, and then the outer peripheral edge of the bottom member is formed on the lower inner surface of the trunk member. The inner surface is joined, and the lower end edge of the body member is folded inward so as to cover the outer peripheral edge, and the outer surface of the outer peripheral edge of the bottom member is joined by hot air, heat and pressure, ultrasonic waves, or the like. An annular leg portion was formed, and finally the upper peripheral edge of the body member was wound outward to form a mouth edge portion to obtain a container (paper cup) molded into the cup shape of the present invention.

  At this time, a paper cup for forming a top curl portion is formed by winding the upper end opening periphery of the paper cup to which the body portion and the bottom portion are coupled while guiding the outer periphery along the curved groove portion provided on the curl mold. In the top curl forming process, the curved groove portion is composed of a first curl portion and a second curl portion, the first curl portion pre-curls outward with respect to the periphery of the upper end opening of the paper cup, and then the second curl portion. While winding the edge of the opening along the curved groove part, it winds up to approximately one turn, and at the same time, raises the bottom of the paper cup, further winds up the opening edge part along the curved groove part of the second curl part, and winds up more than one turn. After forming a paper cup having a top curl portion (FIG. 13), the top curl portion of the paper cup is heated to a temperature equal to or higher than the melting point of the innermost layer resin applied to the inner surface of the paper cup. Heated blown hot air from the hot air insertion part of the hot air device with, by cooling, it could be the top not to expose the paper edge of the curl portion outside the structure (Figure 16).

<Example 4>
Instead of sticking edge protection tape when forming a blank that is punched out of a laminated sheet for printed side material into a fan-shaped blank, and tapering downward, the edge of the side material is skived in advance. A structure in which the edge of the paper of the top curl portion is not exposed to the outside can be obtained in the same manner as in Example 3 except that the edge is prevented from being exposed by hemming.

A comparative example of the present invention will be described below. <Comparative example 1>
When forming the sealed container, the lower inner surface of the side wall member is joined to the lower inner surface of the cylindrical side wall member so that the outer surface of the bottom member whose outer peripheral edge rises downward is joined to the outer surface. Is crimped and joined to the inner surface of the outer peripheral edge portion of the bottom member with a knurling, and is attached to the lower portion of the side wall member (the top caulking portion 3 in FIG. 6 bottom caulking part 5).

  At that time, hot air is blown to the lower inner surface of the cylindrical side wall member and the outer surface of the outer peripheral edge portion of the bottom member to soften the heat-adhesive resin of the inner side layer of the side wall member, and heat bonding of the outer layer of the outer peripheral edge portion of the bottom member Each soft resin was softened, and the inner layer surface of the side wall member bent inward by less than one turn and the outer layer surface of the outer peripheral edge portion of the bottom member were joined by thermocompression bonding.

<Comparative Example 2>
When molding a paper cup, the top curl of the paper cup is cooled by blowing hot air having a temperature equal to or higher than the melting point of the innermost layer resin applied to the inner surface of the paper cup from the hot air insertion portion of the hot air device. A container (paper cup) molded into a cup shape was obtained in the same manner as Example 2 except that there was no.

<Comparison result>
In the sealed paper containers of the present invention of Example 1 and Example 2, there was no problem due to water penetration into the container member in showering and retort sterilization after filling the contents.

  On the other hand, in the conventional sealed paper container of Comparative Example 1, there was a problem due to water penetration from the top caulking portion or the bottom caulking portion.

  In the paper cups of Examples 3 and 4 of the present invention, the edges of the paper members were all sealed, so no problems due to water penetration were seen, but in the conventional paper cup of Comparative Example 2, the top curl portion was An example of softening and deformation due to water penetration was observed.

Example of paper container appearance (a) Cylindrical shape (b) Square prism shape Cross-sectional schematic diagram of an example of a top caulking portion of a conventional paper container Cross-sectional schematic diagram of an example of the top caulking portion of the paper container of the present invention Example of paper container appearance (a) Cylindrical shape (b) Square prism shape Cross-sectional schematic diagram of an example of a top caulking portion of a conventional paper container Cross-sectional schematic diagram of an example of a bottom caulking portion of a conventional paper container Cross-sectional schematic diagram of an example of a side seal part of a conventional paper container (cylindrical) Cross-sectional schematic diagram of an example of a side seal part of a conventional paper container (square column shape) Cross-sectional schematic diagram of an example of a caulking portion of the paper container of the present invention Cross-sectional schematic diagram of an example of the side seal portion of the paper container (cylindrical shape) of the present invention Cross-sectional schematic diagram of an example of the side seal portion of the paper container (square column shape) of the present invention Example of paper container appearance (paper cup) Cross-sectional schematic diagram of an example of the top curl part of a conventional paper container (paper cup) Cross-sectional schematic diagram of an example of the bottom caulking part of a conventional paper container (paper cup) Cross-sectional schematic diagram of an example of a side seal part of a conventional paper container (paper cup) Cross-sectional schematic diagram of an example of the top curl portion of the paper container (paper cup) of the present invention Cross-sectional schematic diagram of an example of the bottom caulking portion of the paper container (paper cup) of the present invention Cross-sectional schematic diagram of an example of the side seal portion of the paper container (paper cup) of the present invention Cross-sectional schematic diagram of an example of the layer configuration of the laminated sheet used in the paper container of the present invention Cross-sectional schematic diagram of an example of the layer configuration of the laminated sheet used in the paper container of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Top material 2 ... Side material 3 ... Top caulking part 4 ... Bottom material 5 ... Bottom caulking part 6 ... Side seal part 7 ... Edge protection tape 8 ... Top curl part 9 ... Spout part 10 ... Paper 11 ... Thermal adhesive resin DESCRIPTION OF SYMBOLS 12 ... Thermal adhesive resin 13 ... Printing layer 14 ... Barrier film 15 ... Plastic film 16 ... Primer layer 17 ... Inorganic oxide vapor deposition layer 18 ... Gas barrier layer

Claims (7)

A paper container composed of a laminated sheet obtained by laminating paper and a plastic film, and in order to protect the edge of the paper constituting the paper container, the edge is folded and the edge is wound between the paper, or the edge including the edge A paper container characterized in that the edge is not exposed to the outside by sticking a tape to the part.   A container that has a top material, a side material, and a bottom material, and is molded into a cylindrical or quadrangular prism shape. When forming a part that bonds the side material and the top material, the top side end of the side material is placed inside the container. 2. The paper container according to claim 1, wherein in the curling step, the edge of the side material end is curled at least one turn so that the edge of the side material end is not exposed to the outside of the container.   A container that has a top material, a side material, and a bottom material, and is molded into a cylinder or a quadrangular prism, and when the side material and the top material and the side material and the bottom material are bonded to each other, the top side of the side material And in the step of curling the bottom end to the inside of the container, the edge of the side material end is not exposed to the outside of the container by curling the side material end more than once. A paper container as described in 1. A container that has a top material, a side material, and a bottom material, and is molded into a cylindrical or quadrangular prism shape, where the side material edge is facing both the inside and the outside of the container. 4. The paper container according to claim 3, wherein the end portion is structured such that the edge of the end portion of the side material is not exposed to the inside and the outside of the container by bonding a tape-like film.   A container that has a side material and a bottom material, and is molded into a cup shape. In the step of curling the top side end of the side material outward, the end of the side material is curled one or more times, and is further subjected to thermocompression bonding or The paper container according to claim 1, wherein the paper container is formed into a flange shape by applying sonic pressure so that the edge of the paper on the side material top side end surface is not exposed to the outside. In the process of curling the bottom side end of the side material to the inside of the container when forming the part that has the side material and the bottom material and molded into a cup shape and bonds the side material and the bottom material, 6. The paper container according to claim 5, wherein the edge of the paper on the side of the side material bottom side is not exposed to the outside by curling the end of the side material for one or more rounds. A container that has a side material and a bottom material and is molded into a cup shape, and in the part where the side materials are bonded together, both ends of the side material end facing the inside and outside of the container are tape-shaped. The paper container according to claim 5 or 6, wherein the edge of the side member is not exposed to the inside and the outside of the container by pasting the film or by skive hemming.