JP5680917B2 - Paper container - Google Patents

Description

  The present invention relates to a paper container. More specifically, the present invention relates to a paper container having a polyethylene terephthalate (PET) laminate layer on the inner surface of the container and a method for manufacturing the same.

  A paper container having a polyethylene terephthalate (PET) laminate layer on the inner surface of the container is described in Patent Document 1, for example.

  Polyethylene terephthalate (PET) is excellent in heat resistance and has the advantage that the resin itself has less odor, the resin odor does not transfer to the container contents, and the odor or scent of the container contents does not adsorb to the PET. Accordingly, a paper container having a polyethylene terephthalate (PET) laminate layer on the inner surface of the container is, for example, a container for soft drinks such as juices, or a filling container for foods cooked in an oven such as a gratin or cake or a microwave oven. Or it has been used as a packaging container.

  However, in the prior art, instead of directly laminating PET on the surface of the paper substrate, as shown in FIG. 1 of Patent Document 1, a low melting point film such as low density polyethylene is first formed on the surface of the paper substrate. A laminated structure in which a PET film is laminated on the upper surface of this low density polyethylene has been used. Since PET resin is relatively easy to crystallize and harden, it has a very high melting point compared to general-purpose laminate resin and is not suitable for extrusion lamination. Even if it can be extruded onto the paper surface, it tends to harden due to the temperature difference, so that the adhesive force with the paper at the time of lamination tends to be insufficient and peels off. Therefore, generally, a low density polyethylene layer has been used as an adhesive layer. Moreover, even if the adhesive strength with the paper is increased by using the low density polyethylene layer as an adhesive layer, it does not change that the adhesive strength between the polyethylene layer and the PET resin layer cannot be sufficiently secured, and the interface layer between the films. Will peel off.

  When a paper container in which a PET film is laminated through a low-density polyethylene adhesive layer as described in Patent Document 1 is heated in an oven or a microwave oven, the low-density polyethylene in the adhesive layer is partially melted, and the upper surface There was a tendency to deteriorate the adhesion of the PET film. That is, the adhesive strength of the PET film is reduced, and partial “lifting” may occur.

  Another disadvantage associated with the use of the low density polyethylene adhesive layer is that when hot water is poured into the container, the low molecular weight component of the polyethylene volatilizes and a strange odor or unique odor is felt. In particular, beverages with a light taste, such as tea and tea, have a great influence.

  Furthermore, another disadvantage associated with the use of a low density polyethylene adhesive layer is that low heat resistance may be a problem. With the recent evolution of fast food, it has been proposed to heat cook food directly in a microwave oven as it is packaged in a container. However, containers with aluminum foil or PET film laminated via a low-density polyethylene adhesive layer will reduce the rigidity of the container when cooked in a microwave oven, and the container will be significantly deformed if an attempt is made to grasp the container with bare hands after heating. Sometimes spilled out of the container.

JP 2007-91323 A

  Accordingly, an object of the present invention is to provide a paper container manufactured using a base paper obtained by laminating PET directly on the paper surface without using a low-density polyethylene adhesive layer having a low melting point.

  The above-mentioned problem is composed of a container body member and a bottom plate member punched out from a base paper obtained by extruding and laminating PET on one surface of paper, and the container body member and the bottom plate member are integrated with the laminated PET surface inside. This is solved by a paper container.

  It has been discovered that a thin PET layer can be firmly adhered to the paper surface by extruding the molten PET resin onto one surface of the paper from an extruder. Thereby, the PET layer can be directly laminated on the paper without using the low melting point PE adhesive layer. PET resins have a high melting point, but PET resins can be fused together. Therefore, a paper container having a PET layer on the inner surface can be manufactured.

  The problem is that the surface on the container inner surface side of one end of the container body member is cut out to a predetermined thickness, the remaining part is folded and stacked on the notch part, and the exposed surface of the paper layer is PET. It is also solved by a paper container having a skiving treatment part coated with a layer.

  When the skiving treatment part is formed at one end of such a container body member, the cut surface of the paper is not exposed on the inner surface side of the container, so that it is suitable for filling the liquid contents, and the end surfaces of the body member are formed on the PET layer. Therefore, they can be fused to each other.

  A heat insulating layer can also be disposed on the outer surface of the body portion of the paper container of the present invention.

  Thereby, the container of this invention can be used as a heat insulation container.

  Since the paper container of the present invention does not require the use of an adhesive layer such as low melting point polyethylene for laminating the PET layer on the paper surface, there is no problem of off-flavor, high rigidity, and excellent heat resistance. can get. Therefore, the paper container of the present invention can sufficiently withstand cooking by an oven or a microwave oven. Further, since an adhesive layer such as low melting point polyethylene is not used, the container manufacturing cost is also reduced.

It is a partial notch front view of an example of the paper container of this invention, A is the partial expanded sectional view of A part, B is the partially expanded sectional view of B part, C was along cc line It is a partial expanded sectional view of the C section. FIG. 2 is a partially enlarged cross-sectional view taken along line dd in FIG. 1. It is process drawing explaining a skive hemming process. It is a fragmentary sectional view of the paper container of this invention which has a foaming heat insulation layer of low melting-point polyethylene. It is a fragmentary sectional view of the paper container of this invention which has a cylindrical trunk as a heat insulation means.

  Hereinafter, the paper container of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a partially cutaway sectional view of an embodiment of the paper container of the present invention. The paper container 1 of the present invention basically includes a container body member 3 and a bottom plate member 5. As shown in the partially enlarged view A, the container body member 3 has a PET layer 9 on the inner surface of the paper substrate 7. Since the PET layer 9 has a high barrier property and is difficult to transfer odor, it is particularly excellent as a material for forming an inner wall surface of oily or greasy foods or packaging containers. Although not shown, a thermoplastic resin layer such as polyethylene, polyester, or nylon can be disposed on the outer surface of the paper substrate 7 for the purpose of improving the water resistance and aesthetics of the container. However, the presence of the thermoplastic resin layer is not an essential requirement for the paper container 1 of the present invention.

  As shown in the partially enlarged view B, the bottom plate member 5 has the PET layers 9 on both sides of the paper substrate 7. As will be described in detail below, the PET layer 9 can be laminated and bonded to the paper substrate 7, but the PET layer 9 laminated to the paper substrate 7 can be thermally welded to another paper surface. Can not. This is because, in order to remelt the PET layer itself laminated on the paper base material 7, a considerable amount of heat is required, and it must be adhered to the paper base material before it is solidified. It cannot be bonded. This is because, as in the case of extrusion, the melting time is short, so there is not enough time for bonding, and it will solidify if not performed quickly. For this reason, when the body member 3 and the bottom plate member 5 are integrated by laminating and welding the PET layer 9 to both surfaces of the paper base material 7 of the bottom plate member 5, the PET layer on the inner wall surface side of the body member 3 is integrated. 9 and the PET layer 9 on the outer wall surface side of the bottom plate member 5 are brought into contact with each other, and the body member 3 and the bottom plate member 5 can be integrated by thermally welding the contact interface. By inserting the downward bent piece of the bottom plate member 5 into the inside of the upward bent piece of the lower end of the trunk member 3, the trunk member 3 and the bottom plate member 5 are integrated. As a method for integrating the body member 3 and the bottom plate member 5, for example, a commonly known method such as a roll-out (rotational pressure bonding) method or an expander method can be used.

  The partial enlarged C diagram is a partial cross-sectional view taken along the line cc. When the body member 3 is rounded into a cylindrical shape, the PET layer 9 on the body member inner wall surface side comes to the surface of the paper base material 7 on the body member outer wall surface side at the joint. As described above, the laminated PET layer 9 itself cannot be thermally welded to the paper surface. Therefore, in the container 1 of the present invention, as will be described in detail below, one end of the barrel member 3 is bent by a method called skive hemming so that the PET layers 9 face each other. It is molded into.

  FIG. 2 is a partial cross-sectional view taken along the line dd in FIG. As described above, the laminated PET layer 9 itself cannot be thermally welded to the paper surface. Therefore, when forming the body member 3 of the paper container 1 of the present invention, the end surface 11 of the PET layer 9 that is bent by the skive hemming process is the end surface of the PET layer 9 that is the other end of the body member 3 that is not skive hemming process. 13 are superposed so as to be “plane coincidence”, and the PET layers are thermally welded together. The distance from the bent end (bending surface end) to the end surface 11 of the PET layer 9 by skive hemming is about 5 mm to 15 mm, preferably about 7 mm to 12 mm. Therefore, the distance of the overlapping portion (also referred to as “side seam”) between the PET layer 9 bent by the skive hemming process and the PET layer 9 at the other end of the body member 3 not subjected to the skive hemming process is 5 mm to 15 mm. . However, the end surface 13 of the PET layer 9 at the other end of the body member 3 that has not been skived hemming may extend beyond the end surface 11 of the PET layer 9 that has been bent by skive hemming. When the end surface 13 of the PET layer 9 at the other end of the body member 3 that has not been skive-hemmed exceeds the end surface 11 of the PET layer 9 that has been bent by the skive-hemming process, Although it does not adhere to the surface of 7, there is an advantage that the formability of the side seam portion of the container mouth edge portion is improved and the roundness of the container opening portion is improved. It is preferable that the roundness of the container opening is improved, because not only the work of heat-sealing the lid on the upper surface of the container mouth edge of the opening becomes efficient, but also a container seal failure or the like does not occur. The length of the end surface 13 of the PET layer 9 at the other end of the body member 3 that has not been skive-hemmed exceeds the end surface 11 of the PET layer 9 that is bent by the skive-hemming process is several millimeters (for example, 0.1 to 3 mm, preferably Is about 0.5 mm to 1.5 mm). As shown in FIG. 2, in the container 1 of the present invention, the bent PET layer 9 bent by skive hemming must be disposed on the inner wall surface side of the body member 3. When the cut surface (cut edge) 15 of the paper base material 7 exists on the inner wall surface side of the container, the contents of the container penetrate into the paper base material 7 from the cut edge 15, and the mechanical strength of the body member 3, and thus the container 1. There is a possibility of deteriorating the overall mechanical strength. In contrast, if the bent PET layer 9 bent by skive hemming is disposed on the inner wall surface side of the barrel member 3, the container contents are completely prevented from penetrating the paper base material 7, and the container The mechanical strength of 1 is not impaired. Therefore, in this specification, “the position where the end surface of the PET resin laminate layer of the exposed cut edge portion is bent by the skive hemming process or more” is the position of the PET layer 9 bent by the skive hemming process. The position where the end face 11 is “plane coincidence” with the end face 13 of the PET layer 9 at the other end of the barrel member 3 not skive-hemmed and the end face 13 of the PET layer 9 at the other end of the barrel member 3 not skive-hemmed. Means a position beyond the end face 11 of the PET layer 9 at the end bent by skive hemming.

  FIG. 3 is a process diagram of an example of a method for producing the body member of the paper container of the present invention. As shown in step (A), the surface of the paper base 7 in one chord portion of the body member blank 17 is scraped off with, for example, a rotary blade 19 according to a predetermined depth and width. In addition to the rotary blade, a peeling means such as a file or a grinder can also be used. This scraping process is called “skive”. In step (B), a recess 21 for facilitating folding is provided in the vicinity of the substantially central portion of the shaved processing surface, and the innermost portion of the shaving processing surface is vertically shaped. In step (C), bending is performed so that the shaving surface is inside with the recess 21 as the center. This bending process is called “hemming”. Prior to the bending process, a known and customary adhesive can be applied to the scraped surface. The blank 17 obtained in this manner is rounded, and the string portions of the blank are overlapped and bonded together to complete the body member 3 shown in FIG.

  As described above, since the paper container 1 of the present invention has the PET layer 9 having excellent heat resistance on the inner wall surface side, it is particularly suitable for filling with a high temperature liquid or the like. In this case, it is preferable to form a heat insulating layer on the outer wall surface of the paper container 1 in order to prevent high heat from being transmitted to a consumer's finger or the like holding the container 1. For example, as shown in FIG. 4, a paper container 1 </ b> A having a foamed heat insulating layer 23 of a thermoplastic synthetic resin film on an outer wall surface of a trunk member. In order to form the foam insulation layer 23 of the thermoplastic synthetic resin film on the outer wall surface of the trunk member, for example, a thermoplastic synthetic resin film having a relatively low melting point such as polyethylene is laminated on the outer wall surface side of the trunk member. After the body member 3 and the bottom plate member 5 are integrated and molded into a container, when this container is heated to a predetermined temperature, the water in the paper base material 7 is evaporated, and the polyethylene film is formed by the evaporated water. It is foamed and the heat insulation layer 23 can be formed. The thermoplastic synthetic resin film laminated on the outer wall surface side of the body member 3 must be selected to have a melting point lower than that of the PET layer laminated on the inner wall surface side. When a thermoplastic synthetic resin film having a melting point higher than that of the PET layer is laminated on the outer wall surface side of the trunk member, the thermoplastic synthetic resin film cannot be foamed with moisture in the paper. A specific method for forming such a low-melting point thermoplastic synthetic resin film with moisture in the paper to form a heat insulating layer is described in detail in Japanese Patent No. 3014629 held by the present applicant.

  Alternatively, as shown in FIG. 5, a paper container 1 </ b> B in which a body winding 25 is disposed on the outer wall surface side of the body member and a heat insulating space 27 is provided as a heat insulating layer between the body member 3 and the body winding 25 is also used. Is possible. A feature of the body winding 25 is that a hole 29 for heat exchange is provided in the curl portion at the lower end. Since the hole 29 exists, the hot air in the heat insulation space 27 can be replaced with the external cold air by the user pushing and releasing the torso with a finger. Such a heat-insulating bobbin is described in Japanese Patent No. 3953992 owned by the present applicant.

  The method of laminating the PET layer 9 on the paper base material 7 is performed, for example, by extruding a PET resin from one surface of the paper base material 7 from an extruder. In the present invention, the properties of the PET resin necessary for direct extrusion lamination to the paper substrate 7 include a melting point of 230 ° C. or less, a copolymer component ratio of 10 mol% to 40 mol%, and an IV (Intrinsic Viscosity) value. (Dl / g) is preferably in the range of 0.6 to 1.0. When the copolymerization component ratio is less than 10 mol%, the crystallization of PET is fast and the melting point is as high as 230 ° C to 255 ° C. Therefore, the resin temperature must be raised to a temperature of 300 ° C or higher at the time of melting. Lamination is not enough. Further, such a high temperature is not preferable in that the resin is likely to be thermally deteriorated. On the other hand, when the copolymerization component ratio exceeds 40 mol%, almost no crystallization occurs, so that the melting point cannot be found by ordinary DSC (see below). The copolymerized PET resin when laminated to paper is probably not crystallized. On the other hand, when the IV value is less than 0.6, there is a disadvantage that, when the resin is melt-extruded, the melt viscosity is low and stable film formation cannot be performed. On the other hand, if the IV value exceeds 1.0, the resin shear heat generation at the time of melting becomes large, and it is difficult to control the resin temperature and the melt viscosity is lowered. The melting point of the PET resin used in the present invention was measured by a differential scanning calorimetry (DSC) method. The DSC method is a thermal analysis method for measuring a melting point, a glass transition point, and the like by measuring a difference in calorie between a measurement sample and a reference material. The result of DSC measurement is a curve with the heat flow (Heat Flow / mW) on the vertical axis and the temperature and time on the horizontal axis. Although the melting point appears as an endothermic peak, it does not show a distinct sharp peak and may be a broad peak. The copolymer component ratio was measured with a nuclear magnetic resonance apparatus (Bruker, 400 MHz). The IV value is a value obtained by dissolving the resin in a mixed solution of phenol / tetrachloroethane = 60/40 (mass ratio) and measuring at 20 ° C. using an automatic viscosity measuring device (SS-270LC, manufactured by Shibayama Kagaku). The PET resin used in the present invention includes terephthalic acid, isophthalic acid, p-β-oxyethoxybenzoic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-dicarboxyldiphenyladipic acid, sebacic acid, 5- At least one acid component selected from the group consisting of sodium sulfoisophthalic acid or their alkyl ester derivatives, ethylene glycol, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, butanediol, cyclohexanedimethanol, bisphenol A A polyester resin obtained by copolymerization with at least one glycol component selected from the group consisting of ethylene oxide adducts. The PET resin used in the present invention is composed of an acid component containing terephthalic acid as a main component and a glycol component containing ethylene glycol as a main component, and isophthalic acid as a copolymerized acid component and also a copolymerized glycol. It is preferable to use neopentyl glycol or cyclohexanedimethanol as a component. For example, the PET resin used in the present invention is composed of an acid component mainly composed of terephthalic acid and a glycol component mainly composed of ethylene glycol, and a polyester resin obtained by copolymerizing a predetermined amount of neopentyl glycol. Etc. Instead of neopentyl glycol, cyclohexanedimethanol can also be used as a copolymerization component. In addition, an acid component mainly composed of terephthalic acid and a glycol component mainly composed of ethylene glycol, a polyester resin copolymerized with a predetermined amount of isophthalic acid, and an acid component mainly composed of terephthalic acid; A polyester resin comprising a glycol component containing ethylene glycol as a main component and copolymerizing a predetermined amount of isophthalic acid and a predetermined amount of neopentyl glycol or cyclohexanedimethanol can also be used as the PET resin of the present invention. As described above, by changing the type of the component to be copolymerized and the ratio of the copolymerized component, a PET resin having a property capable of being directly laminated on paper can be obtained.

  The film thickness of the PET layer 9 extruded and laminated on one surface of the paper substrate 7 is generally in the range of 10 μm to 100 μm. When the film thickness of the PET layer 9 is less than 10 μm, pinholes may occur in the PET layer 9 or the heat resistance may be insufficient. On the other hand, when the film thickness of the PET layer 9 exceeds 100 μm, the use effect of the PET layer 9 is saturated, which is not economical, and there is a possibility that the assembly of the container may be hindered.

Paper substrate 7 used to produce the paper container of the present invention preferably has a basis weight in the range of ^{100g / m 2 ~400g / m 2} . Moreover, it is preferable that this paper base material 7 has a moisture content within the range of about 3 to 10%. The paper substrate 7 may be composed of virgin pulp alone, but may be composed of a mixture of virgin pulp and recycled pulp.

  In the case of manufacturing a paper container 1A having a foam heat insulating layer 23 as shown in FIG. 4, a barrel member 3 having a PET layer 9 on the inner wall surface side and having, for example, a polyethylene film layer on the outer wall surface side, A container is assembled from the bottom plate member 5 having the PET layer 9 on the wall surface side and the outer wall surface side, and the container is heated at a temperature of about 110 ° C. to about 200 ° C. The heating time is about 20 seconds to about 7 minutes. Arbitrary means such as hot air, electric heat or electron beam can be used as the heating means. If it is heated by hot air or electric heat in a tunnel equipped with conveyor means, mass production can be performed at low cost. The water in the paper evaporates by this heating, foams the polyethylene film layer, and the foam heat insulation layer 23 is formed on the outer wall surface of the body member 3. The method for producing the paper container 1A having the foam heat insulating layer 23 is described in detail in Japanese Patent No. 3014629 held by the present applicant.

As a laminate material for producing the paper container of the present invention, a cup base paper for the trunk and a base paper for the bottom are prepared separately, and a polyethylene terephthalate (PET) resin is required to have a desired thickness. The amount was prepared, and PET was extrusion laminated to the base paper using a general laminating extruder.
A melting point of 180 ° C. to 190 ° C., which is produced by copolymerizing 30 mol% of neopentyl glycol as a glycol component, which comprises an acid component having terephthalic acid as a main component and a glycol component having ethylene glycol as a main component. A PET resin having a temperature of IV and an IV value of 0.78 was prepared. A cup base paper subjected to imine coating treatment with a basis weight of 280 g / m ² was prepared as a base paper. While performing corona discharge treatment, PET resin was extruded at 280 ° C. from a T-die of an extrusion laminating machine, pressurized with cooling with a chill roll, and laminated on the base paper to a film thickness of 40 μm. On the opposite side, the same PET resin as described above was laminated at a film thickness of 40 μm simultaneously by a tandem method. The obtained double-sided laminated base paper was used for a body part, and a body member blank was punched from this base paper.
Next, it is composed of an acid component containing terephthalic acid as a main component and a glycol component containing ethylene glycol as a main component, and is further prepared by copolymerizing 25 mol% of neopentyl glycol as a glycol component. A PET resin having a temperature of IV and an IV value of 0.78 was prepared. A cup base paper subjected to imine coating treatment with a basis weight of 220 g / m ² was prepared as a base paper. While performing corona discharge treatment, a PET resin was extruded at 280 ° C. from a T-die of an extrusion laminating machine, pressurized with cooling with a chill roll, and the PET resin was laminated on the base paper with a film thickness of 30 μm. On the opposite side, the same PET resin as above was laminated at a film thickness of 30 μm by the tandem method. The obtained double-sided laminated base paper was used as the bottom portion, and a blank for a bottom plate member was punched out from this base paper.
The trunk member blank obtained as described above was put on a predetermined skive processing machine, and only the trunk seal surface was skived for about 14 mm, and the skived part was hemmed (folded). The distance from the end of the bent surface by hemming to the end surface 11 (see FIG. 2) of the PET layer was about 7 mm. The end face 11 of the PET layer folded by skive hemming is overlapped with the end face 13 (see FIG. 2) of the other end of the blank for body member that has not been skive hemmed so The body part was molded with a conventional cup molding machine together with a blank for the bottom plate member, and the body part was heated at 400 ° C. with a hot air heater and the bottom plate part was heated at 480 ° C. with a hot air heater. A cup was prepared by sealing and pressing.

As a laminate material for producing the paper container of the present invention, a cup base paper for the trunk and a cup base paper for the bottom plate are prepared separately, and a polyethylene terephthalate (PET) resin can be taken to a desired thickness. The required amount was prepared, and PET was laminated on the base paper using a general laminating extruder.
A melting point of 180 ° C. to 190 ° C. produced by copolymerizing 30 mol% of cyclohexanedimethanol as a glycol component, comprising an acid component having terephthalic acid as a main component and a glycol component having ethylene glycol as a main component. A PET resin having a temperature of IV and an IV value of 0.78 was prepared. A cup base paper subjected to imine coating treatment with a basis weight of 280 g / m ² was prepared as a base paper. While performing corona discharge treatment, a PET resin was extruded at 270 ° C. from a T-die of an extrusion laminating machine, pressurized with cooling with a chill roll, and the PET resin was laminated to a thickness of 50 μm on the base paper. The obtained single-sided laminated base paper was used as a body part, and a body member blank was punched out from the base paper.
Next, it is composed of an acid component having terephthalic acid as a main component and a glycol component having ethylene glycol as a main component, and is further prepared by copolymerizing 30 mol% of cyclohexanedimethanol as a glycol component. A PET resin having a IV value of 0.78 was prepared. A cup base paper subjected to imine coating treatment with a basis weight of 220 g / m ² was prepared as a base paper. While performing corona discharge treatment, PET resin was extruded at 270 ° C. from a T-die of an extrusion laminating machine and pressurized while cooling with a chill roll, and the PET resin was laminated on the base paper with a film thickness of 30 μm. On the opposite side, the same PET resin as above was laminated at a film thickness of 30 μm by the tandem method. The obtained double-sided laminated base paper was used for the bottom plate portion, and a blank for the bottom plate member was punched out from this base paper.
The body member blank obtained as described above is applied to a predetermined skiving machine, hemming and skiving is performed only on the body seal surface, and only 18 mm is skived on the body seal surface and skived. Was hemmed (folded). The distance from the end of the bent surface to the end surface of the PET layer by hemming was about 9 mm. Overlapping so that the end face of the PET layer at the other end of the blank for body member that has not been skived hemming is approximately 1.5 mm larger than the end face of the PET layer that has been bent by skive hemming, to form a desired body member, Using a conventional cup molding machine together with the bottom plate blank, the body is heated at 400 ° C. with a hot air heater and the bottom is heated at 480 ° C. with a hot air heater. did.

As a laminate material for producing the paper container of the present invention, a cup base paper for the trunk and a cup base paper for the bottom plate are prepared separately, and a polyethylene terephthalate (PET) resin can be taken to a desired thickness. The required amount was prepared, and PET was laminated on the base paper using a general laminating extruder.
A melting point of 200 ° C., IV value, produced by copolymerizing 25 mol% of isophthalic acid as an acid component, comprising an acid component having terephthalic acid as a main component and a glycol component having ethylene glycol as a main component. A 0.78 PET resin was prepared. A cup base paper subjected to imine coating treatment with a basis weight of 280 g / m ² was prepared as a base paper. A PET resin was extruded at 280 ° C. from a T-die of an extrusion laminating machine while performing corona discharge treatment, and pressurized while cooling with a chill roll, and the PET resin was laminated to a thickness of 50 μm on the base paper. The obtained single-sided laminated base paper was used as a body part, and a body member blank was punched out from the base paper.
Next, a melting point of 200 ° C. was produced by copolymerizing an acid component mainly composed of terephthalic acid and a glycol component mainly composed of ethylene glycol and further copolymerizing 25 mol% of isophthalic acid as an acid component. A PET resin having an IV value of 0.78 was prepared. A cup base paper subjected to imine coating treatment with a basis weight of 220 g / m ² was prepared as a base paper. While performing corona discharge treatment, a PET resin was extruded at 280 ° C. from a T-die of an extrusion laminating machine, pressurized with cooling with a chill roll, and the PET resin was laminated on the base paper with a film thickness of 30 μm. On the opposite side, the same PET resin as above was laminated at a film thickness of 30 μm by the tandem method. The obtained double-sided laminated base paper was used for the bottom plate portion, and a blank for the bottom plate member was punched out from this base paper.
The body member blank obtained as described above is applied to a predetermined skiving machine, hemming and skiving is performed only on the body seal surface, and only 18 mm is skived on the body seal surface and skived. Was hemmed (folded). The distance from the end of the bent surface to the end surface of the PET layer by hemming was about 9 mm. Overlapping so that the end face of the PET layer at the other end of the blank for body member that has not been skived hemming is approximately 1.5 mm larger than the end face of the PET layer that has been bent by skive hemming, to form a desired body member, Using a conventional cup molding machine together with the bottom plate blank, the body is heated at 400 ° C. with a hot air heater and the bottom is heated at 480 ° C. with a hot air heater. did.

As a comparative example, a container was manufactured using polyethylene laminated base paper. As the polyethylene resin, a low density PE (LDPE) resin having a density of 0.92 and an MFR of 3.0, which is a particularly low odor grade and has a good drawdown property and a low neck-in is prepared. A cup base paper subjected to imine coating treatment with a basis weight of 280 g / m ² was prepared as a base paper. While performing corona discharge treatment, LDPE resin was extruded from a T-die of an extrusion laminating machine at 310 ° C., cooled with a chill roll, and an LDPE laminated base paper was prepared while securing a layer thickness of 20 μm at a line speed of about 100 m / min. On the opposite side, the same LDPE resin as described above was simultaneously laminated in a tandem method with a film thickness of 20 μm. Both the container body member blank and the bottom plate member blank were punched out from the obtained double-sided laminated base paper. The body member blank obtained as described above is hung on a predetermined skive processing machine, hemming and skiving is performed only on the body seal surface, and a desired blank shape is obtained, together with a bottom plate member blank, by a conventional cup molding machine. The body portion was heated at 400 ° C. with a hot air heater, and the bottom portion was heated at 430 ° C. with a hot air heater.

For each paper container obtained in Examples 1 to 3 and Comparative Example, (1) Adhesion between base paper and laminate film, (2) Cup stiffness, (3) Laminate film odor evaluation, (4) Each was tested for flavor resistance and (5) pinhole resistance.
(1) The unit of adhesion between the base paper and the laminate film is indicated by N / 15 mm. In the test method, one end of the laminate film is gripped and peeled off from the base paper, and the tensile strength at that time is measured. When the adhesiveness of the laminate film is high, it is not peeled off from the base paper and the paper layer is broken.
(2) The unit of cup stiffness is indicated by N. The test method poured the hot water of each temperature of 95 degreeC and 80 degreeC into the container, and measured the intensity | strength when the container was buckled, putting hot water before the temperature fell.
(3) Laminate film odor evaluation was carried out by pouring hot water at 95 ° C. into the container, and then two panelists evaluated the odor inside the container by a sensory test.
(4) For flavor resistance, 80 ° C. tea was poured into the container, and then two panelists evaluated the presence or absence of odor transfer to the tea inside the container by a sensory test.
(5) With respect to pinhole resistance, a 5% alcohol solution of methylene blue was put inside each paper cup, and after standing for 15 minutes, the state of the laminate film being cut or pinholes was evaluated from the colored state of the inner surface.
The measurement results are summarized in Table 1 below.

As is clear from the results shown in Table 1, there is not much difference in adhesion between PE and PET and the glass transition point of PE is −40 ° C. The film odor is detected, the cup stiffness is low, and the flavor resistance and pinhole resistance are also poor. On the other hand, a container made by directly laminating PET with excellent heat resistance on base paper has high cup rigidity even when hot water is poured, no odor of the film is detected, and flavor resistance and pinhole resistance are completely problematic. There is no. Therefore, a paper container obtained by directly laminating PET on a base paper without using a low melting point film such as PE can be used as a food packaging container that is directly cooked in a microwave oven or the like in addition to the use of pouring hot water. .
Moreover, compared with the paper container obtained in Example 1, the paper container obtained in Example 2 and Example 3 is the end face of the PET layer at the other end of the blank for body member that is not skive-hemmed. Is overlapped so as to exceed the end face of the PET layer bent by skive hemming process by about 1.5 mm, the roundness of the opening of the paper container obtained in Example 2 and Example 3 was implemented. It was better than the roundness of the opening of the paper container obtained in Example 1.

A melting point of 200 ° C., which is produced by copolymerizing 25 mol% of neopentyl glycol as a glycol component, comprising an acid component having terephthalic acid as a main component and a glycol component having ethylene glycol as a main component. A PET resin having a value of 0.78 was prepared. A cup base paper subjected to imine coating treatment with a basis weight of 280 g / m ² and a water content of 7.6% was prepared as a base paper. Extruding PET resin at 280 ° C from a T-die of an extrusion laminating machine while performing corona discharge treatment, pressurizing while cooling with a chill roll, and laminating PET resin on the base paper with a film thickness of 40 µm at a line speed of 60 m / min. . On the other side, a low density polyethylene resin with a density of 0.92 and MFR 3.0 is extruded at 300 ° C. from a T-die of an extrusion laminating machine while simultaneously performing corona discharge treatment by a tandem method, and pressurized while cooling with a chill roll, LDPE resin was laminated with a film thickness of 70 μm on the base paper at a line speed of 60 m / min. The obtained double-sided laminated base paper was used as a base member base paper. A blank for a container trunk member was punched from this base paper by a conventional method.
As the base paper for the bottom member, a double-sided laminated base paper having a layer structure composed of the same polyethylene terephthalate resin layer (40 μm thickness) / base paper layer (basis weight of cup base paper 220 g / m ² ) / polyethylene terephthalate resin layer (30 μm thickness) was used. . A blank for a container bottom member was punched from this base paper by a conventional method.
The trunk member blank was placed on a predetermined skive processing machine, and only the trunk seal surface was skived for about 18 mm, and the skived part was hemmed (folded). The distance from the end of the bent surface to the end surface of the PET layer by hemming was about 9 mm. The end face of the PET layer at the other end of the blank for body member that has not been skived hemming is overlapped so that the end face of the PET layer folded by the skive hemming process is approximately 2.0 mm, and a desired body member is formed, Using a conventional cup molding machine together with a blank for the bottom member, the body is heated at 400 ° C. with a hot air heater and the bottom is heated at 480 ° C. with a hot air heater. did.
Paper cups obtained with these desired cup molding machines were placed in a heating oven at a temperature of 125 ° C., and the heating time was changed to foam only the LDPE layer on the outer wall surface of the container body. When the thickness of the obtained foamed layer was measured while observing with a microscope, 0.80 mm and a thickness suitable for heat insulation were obtained in 5 minutes of heating time.
For comparison, data of a paper cup manufactured by the method described in Japanese Patent No. 3014629 is also shown. The paper cup manufactured by the method described in Japanese Patent No. 3014629 also formed a foam heat insulation layer having a thickness of 0.80 mm in a heating time of 5 minutes.

  From the results shown in Table 2, it is expected that the paper container of the present invention exhibits excellent heat insulation comparable to the heat insulating paper container described in Japanese Patent No. 3014629.

As mentioned above, although the preferable embodiment was mentioned and demonstrated concretely about the paper container of this invention, the paper container of this invention is not limited to the illustrated embodiment. For example, in the case of forming a heat insulating layer, not only the method disclosed in the exemplified patent publications, but also all methods or means used or known to those skilled in the art for heat insulation of paper containers Can be used.
In addition, the paper container of the present invention can be a sealed container by covering the rim with a lid. In this case, since the high gas barrier PET layer 9 is used on the inner wall surface of the container, it is preferable to use a high gas barrier material for the lid forming material. Such a container can prevent the rancidity of oil when filled with oily food, and is particularly suitable for long-term storage of oily food.
The paper container of the present invention can be used for filling and packaging fluid and semi-solid foods in addition to solids and liquids.

1, 1A, 1B Paper container of the present invention 3 Body member 5 Bottom plate member 7 Paper base material 9 PET layer 11 End surface 13 of PET layer 9 bent by skive hemming process The other end of the body member 3 not subjected to skive hemming process End surface 15 of PET layer 9 of paper 17 Cut edge 17 of paper base material 7 Body member blank 19 Rotary blade 21 Recess 23 Foam heat insulation layer 25 Body winding 27 Heat insulation space 29 Hole

Claims (7)

A paper container comprising at least a trunk member and a bottom plate member,
The barrel member is extruded and laminated with a PET resin on one surface of a paper substrate, and the bottom plate member is extruded and laminated with a PET resin on both sides of the paper substrate,
The body member is formed in a cylindrical shape by overlapping and bonding one string and the other string, the one string is bent by a skive hemming process, and the cut edge of the paper base is formed by a PET layer. The other string has the cut edge of the paper substrate exposed,
The exposed cut edge portion of the PET resin laminate layer has an end face that is bent over by the skive hemming process, and is bent by the skive hemming process so that the cut edge of the paper substrate is formed by the PET resin laminate layer. Bonding by thermally welding the PET resin laminate layer of the one string and the PET resin laminate layer of the other string so that the coated side is on the inner wall surface side of the body member,
The trunk member and the bottom plate member are bonded by thermally welding the PET resin laminate layers ,
The PET resin has a melting point of 230 ° C. or less, a copolymerization component ratio of 10 mol% to 40 mol%, and an IV (Intrinsic Viscosity) value (dl / g) of 0.6 to 1.0.
A paper container characterized by that. The PET resin is composed of an acid component containing terephthalic acid as a main component and a glycol component containing ethylene glycol as a main component, and at least one selected from the group consisting of isophthalic acid, neopentyl glycol and cyclohexanedimethanol. The paper container according to claim 1 , which is a polyester resin obtained by copolymerization with a component. The distance from the end surface of the bent surface to the end surface of the PET resin laminate layer by skive hemming is 5 mm to 15 mm, and the end surface of the PET resin laminate layer at the exposed cut edge portion is bent to 0 by the end surface of the PET resin laminate layer. The paper container according to claim 1 or 2, which exceeds the distance in the range of 1 mm to 3 mm. The distance from the end portion of the bent surface to the end surface of the PET resin laminate layer by skive hemming is 7 mm to 12 mm, and the end surface of the PET resin laminate layer at the exposed cut edge portion is 0 by the end surface of the PET resin laminate layer bent by the skive hemming processing. 4. A paper container according to claim 3, which exceeds a distance in the range of 5 mm to 1.5 mm. The paper container according to claim 1 , wherein heat insulating means is further disposed on the outer wall surface of the body member. The paper container according to claim 5, wherein the heat insulating means is a foam heat insulating layer of a low-melting point thermoplastic synthetic resin film laminated on the outer wall surface of the body member. The paper container according to claim 5, wherein the heat insulating means is a cylindrical shell wound disposed on the outer wall surface of the body member, and a heat insulating space is formed between the outer wall surface of the body member and the cylindrical shell coil. .

Images