Paper cup with resealable lid

Abstract

To surely expose an adhesive layer (resealing layer) without paper peeling when peeling the lid member off a paper cup.SOLUTION: A paper cup with lid includes a paper cup body, which is provided with a body part 11 and a bottom part that closes the lower end of the body part 11, and has a flange part formed at the upper end of the body part 11, and a lid member 20 that adheres to the upper surface of the flange part and closes the upper end opening of the body part 11. The body part 11 is composed of, from its inner surface to its outer surface, a sealing layer (for example, low-density PE) 11d, a reinforcing layer (for example, drawn PET) 11c, a paper layer 11a, and a protective layer (for example, low-density PE) 11b. The lid member 20 includes a sealing layer 20e, an adhesive layer 20c, and a peel layer 20d. The reinforcing layer 11c prevents cracks 71, which could cause the paper to peel, from reaching the paper layer 11a.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a paper cup with a lid that has a resealing function. [Background technology]

[0002] Patent Document 1 discloses a paper cup for filling yogurt. The paper cup is made of polyethylene-coated paper, which is paper (cup base paper) coated with low-density polyethylene. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-192083

[0004] By heat-welding a lid to the top edge of a paper cup made of polyethylene-coated paper, the top opening surrounded by the top edge of the paper cup is closed by the lid. If polyethylene-coated paper, which is paper coated with low-density polyethylene, is used for the paper cup, when the lid is peeled off, the lid does not peel off at the boundary between the lid and the paper cup, and the paper on the paper cup side may stick to the back of the lid and peel off (paper cohesive failure, paper peeling).

[0005] There is a demand for a resealing function in the lid material that closes the top opening of a paper cup. In this case, the lid material is provided with a sealing layer and an adhesive layer so that the top opening of a paper cup that has been opened by peeling off the lid material can be resealed with the lid material. In the initial state (when shipped from the factory), the sealing layer bonds the paper cup and the lid material together, closing the cup opening. By exposing the adhesive layer, which is the inner layer of the sealing layer, when the lid material is peeled off, the cup opening can be resealed with the lid material using the exposed adhesive layer instead of the sealing layer.

[0006] However, when the paper peels off the paper cup as described above, the peeled paper sticks to the lid, preventing the adhesive layer from being exposed. In other words, the peeled area cannot be reattached to the lid and resealed.

[0007] The above-mentioned "paper peeling" will be explained in an easy-to-understand manner with reference to Figures 6 to 8. Figure 6 is a partially enlarged cross-sectional view showing the state of the lid material 50 and paper cup 60 in the prior art before they are opened. Figures 7 and 8 are enlarged cross-sectional views showing the state in which paper peeling occurs when the lid material 50 is peeled off, with Figure 7 showing the state just before paper peeling occurs and Figure 8 showing the state in which paper peeling has occurred. In Figures 6 to 8, the thicknesses of the multiple layers that make up the lid material 50 and paper cup 60 are depicted with considerable emphasis.

[0008] Referring to Figure 6, the paper cup 60 is constructed by laminating low-density polyethylene layers 62, 63 on both sides of a paper layer 61. The lid material 50 is constructed by laminating a film composed of a surface resin layer 52, an adhesive layer (resealing layer) 53, a peel layer 54, and a seal layer 55 on the base material layer 51 via an adhesive layer (not shown). The lid material 50 is sealed to the edge of the opening of the paper cup 60, thereby closing the opening of the paper cup 60. In the initial state (before opening), the low-density polyethylene layer 62 of the paper cup 60 in contact with the lid material 50 and the seal layer 55 of the lid material 50 are heat-sealed.

[0009] Paper peeling occurs when the adhesive layer 53 and the peeling layer 54 of the lid material 50 do not separate properly when the lid material 50 is peeled off from the paper cup 60, causing damage (tears) in the paper layer 61 of the paper cup 60. Referring to Figure 7, if the adhesive layer 53 and the peeling layer 54 of the lid material 50 do not separate properly while the lid material 50 is being peeled off, cracks 70 will occur in the peeling layer 54 and the sealing layer 55 of the lid material 50, as well as in the low-density polyethylene layer 62 that contacts the lid material 50 of the paper cup 60, and in the paper layer 61 of the paper cup 60. Unlike the resin layer, the paper layer 61 is manufactured by agglutinating plant and other fibers. Therefore, if a lateral force (the force when peeling off the lid material 50) occurs at the crack 70, paper peeling (cohesive failure in the paper layer 61) will occur, as shown in Figure 8. When paper peeling occurs, the adhesive layer 53 of the lid material 50 will not be exposed at that location, making it impossible to reseal the cup opening using the adhesive layer 53, as described above. Summary of the Invention [Problem to be solved by the invention]

[0010] The object of this invention is to reliably expose the adhesive layer (resealing layer) without causing the paper to peel off when the lid material is peeled off from the paper cup.

[0011] The paper cup with lid and resealing function according to this invention comprises a paper cup body having a cylindrical body and a bottom that closes the lower end of the body, with a flange formed at the upper end of the body by folding the upper end of the body outward, and a lid material that is adhered to the upper surface of the flange and closes the upper end opening of the body, characterized in that the body is composed of a sealing layer, a reinforcing layer and a paper layer from its inner surface to its outer surface, and the lid material is composed of a sealing layer, a peeling layer, an adhesive layer and a base layer, or a sealing layer, an adhesive layer, a peeling layer and a base layer from its inner surface to its outer surface.

[0012] The paper cup with lid according to this invention comprises a paper cup body and a lid material. The top end of the paper cup body is open, and the top opening is closed by the lid material. To make it easier to adhere the lid material, the top end of the body of the paper cup body is folded outward to form a flange. The flange may be formed by simply folding the top end of the body outward, or by rolling (curling) the top end of the body outward. The curled part may also be flattened by flange pressing, which crushes the curled part from above and below. In either case, a flange is formed around the top opening of the body, and the top opening of the body is closed by adhering the lid to the top surface of this flange.

[0013] By folding or rolling the upper end of the body outward, the inside (inner surface) of the body reaches the upper surface of the flange. That is, in the flange, the sealing layer, reinforcing layer, and paper layer are arranged in this order from the upper surface to the lower surface, and the sealing layer comes into contact with the lid material. Note that the reinforcing layer only needs to be positioned so that it is sandwiched between the sealing layer and the paper layer, and other functional layers may be present between the sealing layer and the reinforcing layer, and between the reinforcing layer and the paper layer.

[0014] According to this invention, a reinforcing layer is laminated between the sealing layer and paper layer that make up the body of the paper cup. The reinforcing layer is strong enough to resist cracking even when pulled, so even if the peeling layer and adhesive layer of the lid do not separate properly while the lid is being peeled off and the force of peeling the lid is transmitted to the paper cup, causing a crack in the sealing layer of the body of the paper cup, the progression (transmission) of the crack is stopped at the reinforcing layer, preventing it from reaching the paper layer. By preventing the occurrence of cracks that reach the paper layer in the paper cup body (flange portion) when the lid is peeled off, which could trigger cohesive failure (i.e., paper peeling), paper peeling can ultimately be prevented.

[0015] In a preferred embodiment, the adhesive strength between the peelable layer and adhesive layer of the lid material is smaller than the adhesive strength between the other layers constituting the lid material and the adhesive strength between the layers constituting the body. Because the adhesive strength between the peelable layer and adhesive layer of the lid material is smaller than the adhesive strength between the other layers constituting the lid material and the adhesive strength between the layers constituting the body, when the lid material is peeled off, separation occurs between the peelable layer and adhesive layer of the lid material adhered to the upper surface of the flange, exposing the adhesive layer of the lid material to the outside. The exposed adhesive layer can be used to reseal the lid material.

[0016] Preferably, the reinforcing layer includes a stretched resin film. By laminating the stretched resin film on the upper layer of the paper layer, it is possible to reliably suppress the occurrence of cracks in the paper layer, which are the trigger for the occurrence of paper peeling. The stretched resin film can be a stretched PET (polyethylene terephthalate) film, a stretched polyamide film, a stretched EVOH (ethylene-vinyl alcohol copolymer) film, a stretched PE (polyethylene) film, a stretched PP (polypropylene) film, or the like.

[0017] In other embodiments, the reinforcing layer includes an extruded resin layer other than polyethylene. By extruding and laminating a resin other than polyethylene onto the top layer of the paper layer, it is possible to reliably suppress the occurrence of cracks in the paper layer that can cause paper peeling. For the extruded resin layer other than polyethylene, polyamide, EVOH, PP (polypropylene), etc. can be used. Although PE (polyethylene) is also included in extruded resins, PE is not used in the reinforcing layer due to its low tensile strength. However, since the tensile strength of PE increases when it undergoes a stretching process, stretched PE film can be used in the reinforcing layer, as mentioned above.

[0018] Preferably, the stretched resin film or extruded resin layer other than polyethylene that constitutes the reinforcing layer has a thickness of 5 to 30 μm. The reason for having a thickness of 5 μm or more is that it is difficult to laminate thinner films or resin layers by extrusion molding. The reason for having a thickness of 30 μm or less is that if even thicker films or resin layers by extrusion molding are laminated, the formability of the paper cup may deteriorate.

[0019] Preferably, a protective layer (such as low-density polyethylene) is laminated on the outer surface of the paper layer of the body, which can protect the outer surface of the paper layer. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a perspective view of a paper cup with a lid. [Figure 2] 2 is a cross-sectional view of the paper cup with lid taken along line II-II in FIG. 1. [Figure 3] FIG. 2 is a partially enlarged cross-sectional view showing the state of adhesion between the lid material and the paper cup body that constitute the lidded paper cup. [Figure 4] FIG. 4 is a partially enlarged cross-sectional view equivalent to FIG. 3, showing the state in which the lid is being peeled off from the lidded paper cup. [Figure 5] FIG. 10 is a partially enlarged cross-sectional view showing the state of adhesion between the lid material and the paper cup body that constitute another embodiment of the lidded paper cup. [Figure 6] FIG. 10 is a partially enlarged cross-sectional view showing the state of adhesion between the lid material and the paper cup that constitute a conventional paper cup with a lid. [Figure 7] FIG. 7 is a cross-sectional view equivalent to FIG. 6, showing a crack that reaches the paper layer. [Figure 8] FIG. 7 is a cross-sectional view equivalent to FIG. 6 showing the state in which paper peeling occurs. DETAILED DESCRIPTION OF THE INVENTION

[0021] Fig. 1 is a perspective view of a paper cup with a lid, and Fig. 2 is a partial cross-sectional view of the paper cup with a lid taken along line II-II in Fig. 1.

[0022] The lidded paper cup 1 has a bottomed paper cup body 10 consisting of a body 11 and a bottom 12, with the top opening closed by a lid material 20. The body 11 has a large top opening and is slightly tapered towards the bottom, with roughly a square tube shape with rounded corners. When viewed from above, the paper cup body 10 is almost square with rounded corners. The shape of the body 11 is not limited to a square tube, but may be cylindrical, triangular, pentagonal or other polygonal tube shape.

[0023] A flange portion 11A that protrudes outward (to the side) over the entire circumference of the opening periphery (upper edge) of the body 11 of the paper cup body 10 is formed integrally with the paper cup body 10 (body 11). The upper surface of the flange portion 11A is formed flat, and the lid material 20 is adhered to the upper surface of the flange portion 11A.

[0024] The upper peripheral edge of the body 11 of the paper cup body 10 is curled outward (curled portion), and the flange portion 11A is formed by crushing the curled portion. The bottom 12 is rectangular, and its peripheral edge is bent downward to stand up (standing formed portion 12A). The bottom 12 fits snugly into the bottom opening of the body 11, and the lower end of the body 11 is folded inward (folded portion 11B), and this folded portion 11B sandwiches the standing formed portion 12A of the bottom 12. The inner and outer surfaces of the standing formed portion 12A of the bottom 12 are bonded or welded to the lower end of the body 11 and the inner surface of the folded portion 11B that sandwich it, and the lower end opening of the body 11 is tightly closed by the bottom 12.

[0025] 3 shows how the lid material 20 is adhered to the sheet that constitutes the body 11 (flange portion 11A) of the paper cup body 10. As described above, the flange portion 11A is formed by curling the upper peripheral edge of the body 11 outward, so the sheet surface that faces the inside (inner surface) of the body 11 of the paper cup body 10 faces upward in the flange portion 11A and faces the lid material 20.

[0026] The sheet that makes up the body 11 is composed of a paper layer 11a, a protective layer (low-density polyethylene layer) 11b laminated on the outer surface of the paper layer 11a, a reinforcing layer (reinforcing layer, crack-suppressing layer) 11c laminated on the inner surface of the paper layer 11a, and a sealing layer (low-density polyethylene layer) 11d laminated on the inner surface of the reinforcing layer 11c. The protective layer (low-density polyethylene layer) 11b on the outer surface of the paper layer 11a is preferably laminated to protect the paper layer 11a, but is not necessarily required, and lamination may be omitted.

[0027] The reinforcing layer 11c provided between the paper layer 11a of the paper cup body 10 and the sealing layer (low-density polyethylene layer) 11d used to seal the lid material 20 functions to prevent paper peeling from occurring in the paper layer 11a when the lid material 20 is peeled off from the paper cup body 10, as will be described later. This will also be described in more detail later, but in more detail, in order to prevent paper peeling from occurring, the reinforcing layer 11c functions to stop cracks that may occur when paper peeling occurs and reach the paper layer 11a (suppress cracking), so that they do not reach the paper layer 11a, thereby ultimately preventing paper peeling from occurring.

[0028] 3 is composed of an adhesive layer 11c2 for bonding to the paper layer 11a and an oriented resin film layer 11c1 for preventing the cracks. The adhesive layer 11c2 may be composed of multiple layers, and an adhesive layer may also be provided between the reinforcing layer 11c and the sealing layer 11d. Stretched PET (polyethylene terephthalate) film, stretched polyamide film, stretched EVOH (ethylene-vinyl alcohol copolymer) film, stretched PE (polyethylene) film, stretched PP (polypropylene) film, etc. can be used as the stretched resin film layer 11c1.

[0029] Stretched resin films are produced, for example, by forming a resin composition into a film using the inflation method or T-die method and then stretching it. Stretched resin films may be single-layered or multi-layered, using multiple resin materials. Multilayer stretched resin films are produced, for example, by forming multiple resin compositions into films using the inflation method or T-die method to form a laminate, and then stretching the resulting laminate. Resin compositions made of different materials are laminated via an adhesive resin. Stretching can improve the transparency, rigidity, strength, and heat resistance of the resin film. Film formation and stretching can be performed using an inflation film-forming machine with a stretching machine built in-line.

[0030] The lid material 20 is formed by laminating a PE sealant film, which is a laminate of a surface resin layer 20b (such as a thermoplastic resin), an adhesive layer (resealing layer) 20c (such as a thermoplastic elastomer and a tackifying resin), a peel layer 20d (such as a thermoplastic resin), and a seal layer 20e (such as a PE (polyethylene) heat seal resin), onto a base layer 20a (such as PET (polyethylene terephthalate)), via an adhesive layer (not shown). The seal layer 20e of the PE sealant film faces the body 11 (the upper surface of the flange portion 11A) of the paper cup body 10. For example, a co-extruded multilayer film (Diamilon (registered trademark)) manufactured by Mitsubishi Chemical Corporation can be used as the PE sealant film. The stacking order of the PE sealant film is not limited to the above order, and the adhesive layer 20c and the peel layer 20d may be reversed. That is, the order may be the base layer 20a, the surface resin layer 20b, the peel layer 20d, the adhesive layer 20c, and the seal layer 20e.

[0031] Examples of thermoplastic resins used for the surface resin layer 20b include olefin resins (ethylene resins, propylene resins, cyclic olefin resins, etc.), amide resins, saponified ethylene-vinyl acetate copolymers, ester resins, styrene resins, carbonate resins, etc. There are no restrictions on the type of resin as long as the adhesive strength with the adjacent layer is designed to be stronger than the adhesive strength between the release layer 20d and the adhesive layer 20c.

[0032] Examples of thermoplastic elastomers used in the adhesive layer (resealing layer) 20c include ethylene-based elastomers, propylene-based elastomers, butene-based elastomers, and styrene-based elastomers. Examples of tackifying resins used in the adhesive layer 20c include rosin-based resins such as natural resin rosin, polymerized rosin, hydrogenated rosin, glycerin ester rosin, and pentaerythritol, terpene-based resins such as terpene, aromatic-modified terpene, terpene phenol, and hydrogenated terpene, petroleum resins such as aliphatic petroleum resins, aromatic petroleum resins, and hydrogenated alicyclic petroleum resins, polybutadiene that is liquid at room temperature, polyisoprene that is liquid at room temperature, and polyisobutylene that is liquid at room temperature.

[0033] Thermoplastic resins used in the peel layer 20d include olefin-based resins (ethylene-based resins, propylene-based resins, cyclic olefin-based resins, etc.), ionomers, amide-based resins, saponified ethylene-vinyl acetate copolymers, ester-based resins, styrene-based resins, carbonate-based resins, etc.

[0034] Examples of the polyethylene heat seal resin used in the seal layer 20e include olefin resins such as low density polyethylene and linear low density polyethylene.

[0035] By heating the sealing layer 11d of the body 11 (flange portion 11A) and the sealing layer 20e of the lid material 20, they are thermally welded together, the lid material 20 is relatively firmly attached to the paper cup body 10, and the upper end opening of the body 11 of the paper cup body 10 is tightly closed.

[0036] The adhesive strength between the peeling layer and adhesive layer constituting the lid material 20 described above is smaller than the adhesive strength between other layers constituting the lid material 20, the adhesive strength between the multiple layers constituting the paper cup body 10 (body portion 11), and the seal strength between the sealing layer 20e of the lid material 20 and the sealing layer 11d of the paper cup body 10. For this reason, referring to Figure 4, when the lid material 20 is peeled off by being turned upside down, there is no separation at the boundary between the lid material 20 and the paper cup body 10 (i.e., between the sealing layer 11d of the body portion 11 (flange portion 11A) and the sealing layer 20e of the lid material 20), but separation occurs between the adhesive layer 20c and the peeling layer 20d of the lid material 20. The peeling layer 20d and sealing layer 20e of the lid material 20 remain attached to the body portion 11 (flange portion 11A) of the paper cup body 10, and the base material layer 20a, surface resin layer 20b, and adhesive layer 20c are peeled up. By causing separation between the adhesive layer 20c and the peeling layer 20d of the lid material 20, the adhesive layer 20c that is pre-laminated on the inner layer side of the sealing layer 20e is exposed to the outside in the turned-up lid material 20. The exposed adhesive layer 20c can be used to re-adhere (reseal) the lid material 20 to the body 11 (the upper surface of the flange portion 11A).

[0037] If, while the lid material 20 is being peeled upward, separation does not occur between the adhesive layer 20c and the release layer 20d of the lid material 20 and the force peeling the lid material 20 reaches the layer below the release layer 20d, the release layer 20d is destroyed, causing a crack 71. The crack 71 then reaches the paper cup body 10 below the release layer 20d, and when it reaches the paper layer 11a, paper peeling occurs. Here, the reinforcing layer 11c is laminated between the paper layer 11a and the sealing layer 11d that constitute the body 11 of the paper cup body 10, so that the crack 71 that has reached the paper cup body 10 is stopped by the reinforcing layer 11c, preventing the crack 71 from reaching the paper layer 11a and ultimately preventing paper peeling. The stretched resin film layer 11c1 that constitutes the reinforcing layer 11c, such as a PET film, has a maximum tensile strength of approximately 22 N when the thickness is 12 μm and the sample width is 15 mm. The reinforcing layer 11c can resist destruction (cracking) when mechanical load is applied, and even if separation does not occur between the adhesive layer 20c and the peeling layer 20d of the lid material 20, it is possible to prevent the cracks 71 that could cause the paper to peel from reaching the paper layer 11a.

[0038] FIG. 5 shows a state in which a lid material 20 is bonded to a sheet constituting the body portion 11 (flange portion 11A) having another laminated structure (extruded resin layer). It differs from the laminated structure shown in FIG. 3 in that the reinforcing layer 11c is composed of a polyethylene layer 11c3, an adhesive polyolefin layer 11c4, an EVOH (ethylene-vinyl alcohol copolymer) layer 11c5, and an adhesive polyolefin layer 11c6, which are laminated by coextrusion. The tensile strength of EVOH at a thickness of 10 μm is about 12 N, which is relatively high. Therefore, even in the reinforcing layer 11c shown in FIG. 5, it is possible to avoid the formation of cracks 71 that reach the paper layer 11a, thereby preventing paper peeling. Instead of EVOH, polyamide, PP (polypropylene), etc., can be used.

[0039] The extruded resin layer is formed, for example, by a melt extrusion lamination method, in which a resin composition is melted and extruded to form a layer.

[0040] Examples and comparative examples will be described below. [Example]

[0041] Basis weight 320g / m 2 A base paper is prepared, and its coated surface is subjected to corona discharge treatment and anchor coating treatment in that order. Molten low-density polyethylene (Novatec LC520, manufactured by Japan Polyethylene Co., Ltd.) (hereinafter referred to as extrusion resin 1) is extruded onto the treated surface in the form of a film with a thickness of 20 μm, which is then clamped and cooled between a pair of cooling rolls (first extrusion process).

[0042] Corona discharge is applied to the uncoated surface of the base paper that has undergone the first extrusion process, and a 12 μm thick ester film (Toyobo Ester Film E5200, manufactured by Toyobo Co., Ltd.) (hereinafter referred to as stretched resin film 1) is laminated using the extrusion lamination method with the extruded resin 1 as an adhesive layer (second extrusion process). Further, the molten extruded resin 1 is extruded into a film shape with a thickness of 40 μm on the surface where the ester film is laminated (third extrusion process). By going through the first and third extrusion processes, a sheet of body 11 with a layer structure of extruded resin 1 (20 μm) / anchor coat / paper / extruded resin 1 (15 μm) / stretched resin film 1 (12 μm) / extruded resin 1 (40 μm) is produced. The stretched resin film 1 serves as a reinforcing layer.

[0043] The sheet for the bottom 12 was also made using the same process as described above. However, the sheet for the bottom 12 does not necessarily have to have the same layered structure as that for the body 11, and a sheet with a different layered structure may also be used.

[0044] The sheet of body 11 that has undergone the above-mentioned process is punched out to a predetermined shape, the edges are processed by skiving, hemming, etc., and rolled into a square tube with both ends partially overlapping (the grain of the paper is in the vertical direction). The overlapping parts are subjected to a heat treatment such as a flame treatment or hot air treatment to heat and melt the extruded resin 1 in the outermost and innermost layers of the overlapping parts, and the body 11 is formed by pressing using a hot plate or the like.

[0045] The sheet of the bottom 12 was punched into a predetermined shape, and the peripheral edge was bent to form the upright molded portion 12A.

[0046] The bottom 12 is inserted into the body 11 from the upper end opening of the body 11 with the upright molded portion 12A facing downward, and the bottom 12 is fitted into the lower end opening of the body 11. Hot air is blown onto the lower end peripheral edge of the body 11 and the upright molded portion 12A of the bottom 12 to heat and melt the extruded resin 1. The lower end of the body 11 is folded inward to cover the upright molded portion 12A of the bottom 12, and the lower end (folded portion 11B) of the body 11 and the upright molded portion 12A of the bottom 12 are joined by knurling from the inside. The bottom of the paper cup body 10 is completed.

[0047] Finally, the upper end of the body 11 of the paper cup body 10 is curled outward using a curling mold, and the curled portion is crushed from above and below to form the flange portion 11A. The paper cup body 10 is then completed.

[0048] The completed paper cup body 10 had a capacity of 400 cc. No occurrence of pinholes or the like due to burning was observed in the paper cup body 10. [Example]

[0049] In the second extrusion process, a paper cup body 10 was produced in the same manner as in Example 1, except that a uniaxially stretched PE film (PE3K-BT, manufactured by Futamura Chemical Co., Ltd.) (hereinafter referred to as stretched resin film 2) was used instead of stretched resin film 1 (layer structure: extruded resin 1 (20 μm) / anchor coat / paper / extruded resin 1 (15 μm) / stretched resin film 2 (25 μm) / extruded resin 1 (40 μm)). Stretched resin film 2 serves as a reinforcing layer. [Example]

[0050] In the second extrusion process, a corona discharge treatment was applied to the uncoated surface, and 20 μm of molten extruded resin 1, 5 μm of extruded resin 2, 10 μm of EVAL (EVOH) (Kuraray Co., Ltd., EVAL F171B) (hereinafter referred to as extruded resin 3), and 5 μm of extruded resin 2 were layered and co-extruded onto this treated surface. The third extrusion process was not performed (layer structure: extruded resin 1 (20 μm) / anchor coat / paper / extruded resin 1 (20 μm) / extruded resin 2 (5 μm) / extruded resin 3 (10 μm) / extruded resin 2 (5 μm) / extruded resin 1 (20 μm)). Extruded resin 3 serves as a reinforcing layer. [Example]

[0051] In the second extrusion process, a paper cup body 10 was produced in the same manner as in Example 3, except that nylon (MXD6 nylon S6001, manufactured by Mitsubishi Gas Chemical Co., Inc.) (hereinafter referred to as extruded resin 4) was used instead of extruded resin 3 (layer structure: extruded resin 1 (20 μm) / anchor coat / paper / extruded resin 1 (20 μm) / extruded resin 2 (5 μm) / extruded resin 4 (10 μm) / extruded resin 2 (5 μm) / extruded resin 1 (20 μm)). Extruded resin 4 serves as a reinforcing layer. Comparative Example 1

[0052] In the second extrusion process, a corona discharge treatment was applied to the uncoated surface, and molten extruded resin 1 was extruded onto this treated surface to a thickness of 40 μm. The third extrusion process was not performed (layer structure: extruded resin 1 (20 μm) / anchor coat / paper / extruded resin 1 (40 μm)). This is a form without a reinforcing layer.

[0053] For the lid material 20, a multi-layer sealant film was used, in which a base layer 20a was made of 12 μm thick PET (ester film E5200 manufactured by Toyobo Co., Ltd.), a printing layer (gravure ink Finart manufactured by DIC Graphics Inc.) and an adhesive (two-component curing urethane adhesive RU-77T / hardener H-7 manufactured by Rock Paint Co., Ltd.), and a surface resin layer 20b, adhesive layer 20c, peel layer 20d and sealing layer 20e were laminated in this order.

[0054] The base material layer 20a was created by gravure printing ink on one side of a PET film and dry laminating a separately prepared unprinted (unprinted) PET film onto the printed surface of the gravure-printed PET film via a two-component curing urethane adhesive. The lid material 20 was created by dry laminating the surface resin layer 20b of the above-mentioned multilayer sealant film onto the unprinted PET film of the base material layer 20a. In the base material layer 20a, a vapor-deposited PET film may be used instead of the PET film, or an OPP (oriented polypropylene) film, Ny (nylon) film, or MDO-PE (uniaxially oriented polyethylene) film may also be used. A barrier base material such as aluminum foil may also be used. The base material layer 20a may be a single layer, or a multilayer combining one or more types of film.

[0055] In addition to the above-mentioned lid material 20, we also created a lid material 20A with an adhesive layer 20c and a peel layer 20d (i.e., without a resealing function). The lid material 20A includes a base material layer 20a, a surface resin layer 20b, and a seal layer 20e.

[0056] The above-mentioned lid material 20 was placed on the upper surface of the flange portion 11A of the five types of paper cup bodies 10 of Examples 1 to 4 and Comparative Example 1 prepared as described above, and heat-sealed (initial adhesion) under conditions of 160°C, 0.45 MPa, and 1 second, thereby producing five types of lidded paper cups 1. Similarly, the above-mentioned lid material 20A was placed on the upper surface of the flange portion 11A of the five types of paper cup bodies 10 of Examples 1 to 4 and Comparative Example 1, and heat-sealed (initial adhesion) under conditions of 160°C, 0.45 MPa, and 1 second, thereby producing five types of lidded paper cups.

[0057] <Evaluation of paper cups with lids> The paper cups with lids in which the lid material 20 (having an adhesive layer 20c and a peeling layer 20d) was adhered to the five types of paper cup bodies 10 of Examples 1 to 4 and Comparative Example 1 prepared as described above, and the paper cups with lids in which the lid material 20A (without the adhesive layer 20c and the peeling layer 20d) was adhered to the five types of paper cup bodies 10 of Examples 1 to 4 and Comparative Example 1, were subjected to the paper peeling evaluation described below, and the opening strength (adhesion strength) between the lid materials 20 and 20A was measured. Table 1 shows the evaluation test results.

[0058] [Table 1]

[0059] In the paper peeling evaluation, the lidded paper cups were placed horizontally, the lid material 20 was peeled off from the lidded paper cups (see Figure 1), and paper peeling was observed. Paper peeling refers to the fact that the paper layer 11a of the paper cup body 10 that constitutes the lidded paper cup is cohesively peeled off (cohesive failure), and the cup is opened with part of the paper layer 11a remaining attached to the lid material 20.

[0060] The paper cups with lids using the paper cup bodies 10 of Examples 1 to 4 did not experience paper peeling, and the adhesive layer 20c was well exposed in the lid material 20. On the other hand, the paper cup 1 with lid using the paper cup body 10 of Comparative Example 1 experienced paper peeling.

[0061] The opening strength (adhesive strength) was measured as follows.

[0062] The prepared paper cup with lid was placed horizontally, and two 15 mm-wide cuts were made in the periphery of the lid material 20, 20A. The 15 mm-wide area of ​​the lid material 20, 20A was then lifted up to separate the lid material 20, 20A from the flange portion 11A of the paper cup body 10, and the maximum strength was measured. To measure the adhesive strength, a Tensilon universal material testing machine manufactured by A&D Co., Ltd., equipped with a pair of grippers spaced apart in the vertical direction, was used. One (lower) gripper gripped and fixed the paper cup body 10, and the other (upper) gripper gripped the tip of the lid material 20, 20A in the 15 mm-wide area mentioned above. The other gripper was then moved upward to pull the lid material 20, 20A upward (at a 90-degree angle from the surface of the flange portion 11A of the paper cup body 10) until it was completely separated from the flange portion 11A. The speed at which the lid materials 20 and 20A were turned up was 50 mm / min. The measurement points were the corners of the cup, and the above-mentioned cuts were made in the direction connecting a pair of diagonal corners.

[0063] For the lidded paper cups 1 to which the lid material 20 (having an adhesive layer 20c and a peeling layer 20d) was adhered, the adhesive layer 20c and the peeling layer 20d of the lid material 20 separated when the lid material 20 was peeled off from the paper cup body 10, so the opening strength was relatively low. On the other hand, for the lidded paper cups to which the lid material 20A (having no adhesive layer 20c and a peeling layer 20d) was adhered, attempts were made to peel the lid material 20A from the paper cup body 10, but the lid material 20A could not be peeled off for the paper cup bodies of Examples 1 to 4 (opening strength of 70 N or more). This is because the adhesive strength between the adhesive layer 20c and peeling layer 20d that make up the lid material 20 is smaller than the adhesive strength between the other layers that make up the lid material 20 and the adhesive strength between the layers that make up the paper cup body.As a result, the adhesive layer 20c and peeling layer 20d of the lid material 20 can be separated with a light force, but since the lid material 20A does not have the adhesive layer 20c or peeling layer 20d, no separation occurs between the layers in the lid material 20A, and as a result, the lid material 20A could not be peeled off from the paper cup body 10.

[0064] In Comparative Example 1, the lid materials 20 and 20A could be peeled off from both the lidded paper cup with the lid material 20 glued on and the lidded paper cup with the lid material 20A glued on, but since the opening was caused by the paper peeling, there was no significant difference in the opening strength between the lid materials 20 and 20A. [Explanation of symbols]

[0065] 1 paper cup with lid 10 Paper cup body 11 Torso 11a Paper layer 11b Protective layer (low-density polyethylene layer) 11c reinforcement layer 11d Sealing layer (low density polyethylene layer) 11A flange 12 Bottom 20 Lid material 20a Base material layer 20b Surface resin layer 20c Adhesive layer (resealing layer) 20d peel layer 20e sealing layer

Claims

1. The paper cup body has a cylindrical body and a bottom that closes the lower end of the body, and a flange formed at the upper end of the body by folding the upper end of the body outward; and a lid that is adhered to the upper surface of the flange and closes the upper end opening of the body, The body portion is composed of a sealing layer, a reinforcing layer, and a paper layer from its inner surface to its outer surface, The lid material is composed of a seal layer, a peel layer, an adhesive layer and a base layer, or a seal layer, an adhesive layer, a peel layer and a base layer, from its inner surface to its outer surface. A paper cup with a resealable lid.

2. the adhesive strength between the peel layer and the adhesive layer of the lid material is smaller than the adhesive strength between other layers constituting the lid material and the adhesive strength between layers constituting the body part; The resealable paper cup with a lid according to claim 1.

3. The reinforcing layer includes a stretched resin film. The resealable paper cup with a lid according to claim 1.

4. The stretched resin film has a thickness of 5 to 30 μm. The paper cup with a lid having a resealing function according to claim 3.

5. The reinforcing layer includes an extruded resin layer other than polyethylene, The resealable paper cup with a lid according to claim 1.

6. The extruded resin layer has a thickness of 5 to 30 μm. The resealable paper cup with a lid according to claim 5.

7. A protective layer is laminated on the outer surface of the paper layer of the body. The resealable paper cup with a lid according to claim 1.

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