Paper container and method for manufacturing the same

Abstract

By reducing the amount of oil-resistant agent used, costs can be controlled while eliminating uneven application and efficiently penetrating the oil-resistant agent to the areas of the substrate where oil resistance is required. [Solution] The method for manufacturing a paper container according to the present invention includes the steps of: forming a blank bundle by stacking a plurality of fan-shaped paper substrates that will form the body; pressing the blank bundle with a pair of clamping plates by pressing one main surface and the other main surface of the blank bundle with the clamping plates; impregnating at least a portion of the end faces of the blank bundle with an oil-resistant agent via an oil-resistant agent application roller while the blank bundle is pressed with the clamping plates; drying the end faces of the blank bundle that have been impregnated with the oil-resistant agent via a drying device; and after the drying process, separating the paper substrates that have been impregnated with the oil-resistant agent at their lateral ends from the blank bundle and fixing the lateral ends of the paper substrates together to form the body.

Description

Technical Field

[0001] The present invention relates to a paper container excellent in oil resistance and material saving, and a method for manufacturing the same.

Background Art

[0002] Paper containers such as paper cups and paper trays are used for storing foods, beverages, etc. The paper container is formed into a cup shape or a tray shape by combining, for example, a bottom plate and a body portion. Generally, in a paper container, a thermoplastic resin such as polyethylene or a PET film is laminated on the inner surface side of the container to prevent moisture, oil, etc. contained in the above-mentioned foods from penetrating into the body portion and the bottom plate.

[0003] By the way, foods containing a relatively large amount of oil may be stored in a paper container. In such a case, oil, etc. may penetrate into the body portion and the bottom plate of the paper container. In contrast, in Patent Document 1, it is proposed to form a paper container using a water- and oil-resistant paper obtained by impregnating and adhering a fluorine-based oil-resistant agent having a perfluoroalkyl group with a carbon chain length of 6 or less to a base paper mainly composed of porous fibers. Further, in Patent Document 2, it is disclosed that a penetration-preventing coating liquid having water- and oil-resistance is applied by a dispenser or a spray only to the joint portion between the body portions and the joint portion between the body portion and the bottom plate on the inner surface side of the formed paper container.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Disclosure of the Invention

Problems to be Solved by the Invention

[0005] The prior art, including the aforementioned patent documents, still has areas that need improvement, as described below. Specifically, although sufficient oil resistance can be obtained by impregnating the entire base paper with an oil-resistant agent, as in Patent Document 1, the amount of oil-resistant agent used becomes very large, which not only increases costs but also hinders heat sealing, potentially resulting in incomplete molding of the body and bottom plate.

[0006] Furthermore, even with methods such as applying an oil-resistant agent to the inside of a molded paper container using a dispenser or spray, as described in Patent Document 2, there are concerns that the amount of oil-resistant agent used will be large, increasing costs and potentially resulting in uneven application.

[0007] Thus, conventional paper containers and their manufacturing methods have the problem that the amount of oil-resistant agent used is very large, which tends to increase the manufacturing cost of paper containers. Furthermore, with conventional paper containers and their manufacturing methods, if the base material itself is oil-resistant paper, the heat sealability is hindered, which can lead to molding defects between the body and the bottom plate.

[0008] This invention has been made in view of the above-mentioned problems, and aims to provide a paper container and a method for manufacturing the same that can reduce the amount of oil-resistant agent used and thus control costs, while eliminating uneven coating and efficiently penetrating the oil-resistant agent to the areas of the substrate where oil resistance is required. [Means for solving the problem]

[0009] A method for manufacturing a paper container according to one embodiment of the present invention is a method for manufacturing a paper container comprising a bottom plate and a peripheral wall-shaped body portion rising from the periphery of the bottom plate, comprising the steps of: stacking a plurality of fan-shaped paper substrates to form the body portion to form a blank bundle; clamping the blank bundle with a pair of clamping plates by pressing one main surface and the other main surface of the blank bundle, respectively; impregnating at least a portion of the end faces of the blank bundle with an oil-resistant agent via an oil-resistant agent application roller while the blank bundle is pressurized by the clamping plates; drying the end faces of the blank bundle impregnated with the oil-resistant agent via a drying device; and, after the drying process, separating the paper substrates with the oil-resistant agent impregnated at their lateral ends from the blank bundle, and fixing the lateral ends of the separated paper substrates together to form the body portion.

[0010] Furthermore, in the method for manufacturing a paper container as described in (1) above, (2) the oil-resistant agent preferably comprises an oil-resistant resin component, water, and alcohol, and the ratio of the alcohol to the oil-resistant resin component is adjusted so that the surface tension of the oil-resistant agent is 19.2 to 30.3 mN / m.

[0011] Furthermore, in the method for manufacturing paper containers described in (1) above, it is preferable to (3) slide the oil-resistant coating roller and the drying device in parallel against the end face of the blank bundle so that the oil-resistant agent is impregnated into the end face via the oil-resistant coating roller, and then subsequently dry the end face via the drying device.

[0012] Furthermore, in the method for manufacturing a paper container as described in (3) above, it is preferable to have (4) a forward step in which the oil-resistant coating roller and the drying device are slid in a first direction passing directly below the end face to apply and dry the oil-resistant agent to the end face with the oil-resistant coating roller, and a return step in which the oil-resistant coating roller and the drying device are slid in a second direction opposite to the first direction while at least the oil-resistant coating roller is separated from the end face to dry the container with the drying device without applying the oil-resistant agent.

[0013] Furthermore, in the method for manufacturing a paper container described in any of (1) to (4) above, (5) it is preferable to place the end face of the blank bundle on a slit plate with an opening formed therein while the blank bundle is pressed with the clamping plate, and impregnate at least a part of the end face with the oil-resistant agent using the oil-resistant agent application roller through the slit plate while the end face is exposed through the opening.

[0014] Furthermore, in the method for manufacturing a paper container as described in (5) above, (6) when the end face of the blank bundle is supported on the slit plate, it is preferable that the short side of the blank bundle that comes into contact with the bottom plate is supported by a side support member.

[0015] Furthermore, a paper container according to one embodiment of the present invention comprises (7) a bottom plate and a peripheral wall-shaped body portion rising from the periphery of the bottom plate, having a side seam region formed by overlapping and joining one side end and the other side end of a fan-shaped paper substrate, wherein one side end located on the inner surface side of the body portion is formed with an oil-resistant impregnation region having an oil-resistant concentration gradient from the one side end toward the other side end.

[0016] Furthermore, in the paper container described in (7) above, (8) it is preferable that the oil-resistant impregnation region is formed such that the impregnation width of the oil-resistant agent from one side end does not exceed the side seam region.

[0017] Furthermore, in the paper container described in (8) above, (9) a resin layer is laminated to the inner circumferential surface of the paper substrate that is on the inner side, and it is preferable that the impregnation width from one side end is inclined to increase from the inner circumferential surface to the outer circumferential surface in the thickness direction of the paper substrate.

[0018] In the paper container according to (8) above, (10) resin layers are laminated on the inner peripheral surface on the inner side and the outer peripheral surface on the opposite side of the inner peripheral surface of the paper base material, respectively, and the impregnation width from the one side end is preferably inclined so as to increase from the inner peripheral surface and the outer peripheral surface toward the center in the thickness direction of the paper base material.

Advantages of the Invention

[0019] According to the paper container and its manufacturing method in the present invention, it is possible to realize a paper container that reduces the amount of oil-resistant agent used to suppress costs, eliminates coating unevenness, and efficiently penetrates the oil-resistant agent into the necessary areas.

Brief Description of the Drawings

[0020] [Figure 1] It is a schematic diagram showing a paper container according to an embodiment and a blank as a base material constituting the paper container. [Figure 2] It is a cross-sectional view schematically showing the α part in FIG. 1. [Figure 3] It is a schematic diagram showing the state of a blank (paper base material) impregnated with an oil-resistant agent. [Figure 4] It is an enlarged cross-sectional view of the β part in FIG. 2, and is a schematic diagram showing an end part of a body part in a paper container formed using a blank impregnated with an oil-resistant agent. [Figure 5] It is a front view showing the configuration of a manufacturing apparatus for a paper container according to an embodiment. [Figure 6] It is a side view showing the configuration of a manufacturing apparatus for a paper container according to an embodiment. [Figure 7] It is a top view showing the configuration of a manufacturing apparatus for a paper container according to an embodiment. [Figure 8] It is a schematic diagram showing the configuration of a roller coating part in a manufacturing apparatus for a paper container according to an embodiment. [Figure 9] It is a schematic diagram (Part 1) for explaining the placement mode of a blank bundle in the manufacturing method of a paper container according to an embodiment. [Figure 10]This is a schematic diagram (part 2) illustrating the arrangement of the blank bundle in the manufacturing method of a paper container according to the embodiment. [Figure 11] This is a schematic diagram illustrating the method of applying an oil-resistant agent to a blank bundle in a method for manufacturing a paper container according to an embodiment. [Figure 12] This is a schematic cross-sectional view showing the end of the body of a modified paper container. [Modes for carrying out the invention]

[0021] The following description will specifically explain the paper container and its manufacturing method according to this embodiment, with reference to the drawings as appropriate. The following embodiments describe one example to which the present invention is applied, and are not intended to limit the present invention in any way. Furthermore, other known configurations, including those described in the above-mentioned patent documents, may be appropriately supplemented and implemented. In the following, the vertical direction with respect to the installation surface of the device will be defined as the Z direction, the short-side direction of the opening OP (described later) in which the oil-resistant coating roller and drying device move will be defined as the X direction, and the long-side direction of the opening OP will be defined as the Y direction for convenience.

[0022] [Paper container 100] First, the paper container 100 in this embodiment will be described with reference to Figures 1 and 2 as appropriate. As shown in the figures, the paper container 100 in this embodiment can be exemplified by a paper cup made of a paper base material. In the following description, a paper cup will be used as an example of the paper container 100, but various known paper containers having a side seam region on the body, such as a paper tray, are included in the paper container 100 of this embodiment.

[0023] As shown in the figure, the paper container 100 of this embodiment comprises a bottom plate 10 and a peripheral wall-shaped body portion 20 rising from the periphery of the bottom plate 10. The bottom plate 10 has a circular outer shape, for example, if the paper container 100 is cylindrical. The body portion 20 has a peripheral wall-shaped outer shape rising from the periphery of the bottom plate 10 by molding a paper base material 30 such that the body portion 20 surrounds the periphery of the bottom plate 10.

[0024] The paper base material 30, also called a blank, has a general fan shape (or part of a cylindrical shape) in plan view, as shown in Figures 1(b) and 3, and is composed of a main surface 31 (one main surface 31A which is the inner circumferential surface side of the paper cup, and the other main surface 31B which corresponds to the back surface and is the outer circumferential surface side of the paper cup), one lateral end 32 and the other lateral end 33 whose length is defined by L, the long side end 34 which forms the top curl portion when molded into a paper cup, and the short side end 35 which is joined to the periphery of the bottom plate 10 when molded into a paper cup.

[0025] The materials used for the bottom plate 10 and body 20 of such a paper container 100 may include various general papers made of known fibrous materials suitable for paper cups. Furthermore, as shown in Figure 2 and other figures, it is preferable that the bottom plate 10 and body 20 (paper base material 30) have a resin layer LM made of a known resin material (for example, polyethylene film or PET film) laminated to their surfaces. More specifically, in this embodiment, as shown in Figures 1 and 2 and other figures, the resin layer LM is laminated to the inner circumferential surface of the paper base material 30 constituting the body 20, which is the inner surface side of the paper cup.

[0026] As can be seen from Figure 2 and other figures, the body portion 20 of the paper container 100 has a side seam region SS formed by overlapping and joining one side end 32 and the other side end 33 of a fan-shaped paper base material 30. Various known methods can be applied to the joining method described above. For example, the resin layer LM may be heated to heat-weld one side end 32 and the other side end 33, or a known adhesive may be used to bond one side end 32 and the other side end 33. In the paper container 100 of this embodiment, a welded region WP is formed by heat-welding the resin, as shown in Figures 2 and 12, and the side end 32 and the other side end 33 are joined via this welded region WP.

[0027] The body portion 20 of the paper container 100 in this embodiment is provided with an oil-resistant impregnation region RA on one side end 32, which is impregnated with an oil-resistant agent. As such an oil-resistant agent, known fluorine-based or non-fluorine-based oil-resistant materials, including the materials disclosed in the above-mentioned patent documents, can be applied. As an example, in this embodiment, the above-mentioned oil-resistant agent was prepared by adding a predetermined amount of water and ethanol to "Asahi Guard AG-E070," a fluorine-based material manufactured by AGC Inc. The ethanol concentration (wt%) in the oil-resistant agent of this embodiment is preferably 30 to 70. Furthermore, since the oil-resistant agent of this embodiment is prepared using alcohol, an oil-resistant agent of a type that does not separate from alcohol is preferred. Furthermore, the oil-resistant agent of this embodiment is preferably provided with the following properties from the viewpoint of surface tension.

[0028] In other words, as a result of diligent research by the inventors, it was concluded that since the paper substrate 30 as a blank is composed of paper fibers, it is desirable that the oil resistant agent has a surface tension suitable for impregnation of specific parts of the paper fibers. More specifically, the oil resistant agent of this embodiment contains an oil-resistant resin component, water, and alcohol, and it is preferable that the ratio of alcohol to the oil-resistant resin component is adjusted so that the surface tension of the oil resistant agent is 19.2 to 30.3 mN / m.

[0029] By adjusting the surface tension of the oil resistant agent to 19.2 to 30.3 mN / m, it becomes possible to efficiently penetrate the oil resistant agent into the lateral end faces of the blank bundle using the oil resistant agent application roller 221, as described later. In this embodiment, the penetration width of the oil resistant agent into the paper fibers (capillaries) is L (unit: mm), the penetration time of the oil resistant agent into the paper fibers (capillaries) is t (unit: seconds), the radius of the capillaries is r (unit: mm), the surface tension of the oil resistant agent (liquid) is σ (mN / m), the contact angle at the solid-liquid interface between the capillaries and the liquid is θ, and the viscosity of the liquid is η (unit: mPa·s). The surface tension σ was calculated using the following formula.

[0030]

number

[0031] Note that the value of the surface tension σ described above is not limited to this Equation 1, and may be obtained using other known calculation formulas for calculating the capillary force and penetration width due to capillary action. Further, in the present embodiment, water and ethanol were added to and adjusted with respect to "Asahi Guard AG-E070" manufactured by AGC Inc. as the oil-resistant agent used, but it is sufficient to perform the measurement in the same manner using an aqueous dispersion of other known oil-resistant agents.

[0032] As shown in FIG. 3, the oil-resistant agent impregnated region RA of the present embodiment is defined within the side seam region SS from one side end 32 to the other side end 33 in the paper base material 30. The oil-resistant agent impregnated region RA in the present embodiment is formed with a width such that the impregnation width of the oil-resistant agent from the above-described one side end 32 does not exceed the side seam region SS. More specifically, it is preferable that the maximum impregnation width W in the oil-resistant agent impregnated region RA is within a range that does not exceed the above-described side seam region SS.

[0033] The oil-resistant agent impregnated region RA of the present embodiment has a concentration gradient of the oil-resistant agent from one side end 32 toward the other side end 33 side. More specifically, as illustrated in FIG. 4, in the oil-resistant agent impregnated region RA, the impregnation width from one side end 32 is inclined so as to increase from the inner peripheral surface to the outer peripheral surface in the thickness direction of the paper base material 30. In other words, in the present embodiment, since the resin layer LM is laminated on one main surface 31A which is the inner peripheral surface side of the paper cup, it can also be said that the impregnation width from one side end 32 is inclined so as to increase from the side laminated with the resin layer LM to the non-laminated side in the thickness direction of the paper base material 30.

[0034] Also, as shown in FIG. 3, since the upper and lower ends of the paper base material 30 in the present embodiment become the joint portions with the top curl and the bottom plate 10 respectively, it is preferable that the length L1 of the oil-resistant agent impregnated region RA is set to be smaller than the length L of the side end (L1 < L) so as to avoid these regions. Thereby, it becomes possible to suppress the influence of the oil-resistant agent and mold the joint portion with the top curl and the bottom plate 10.

[0035] <Paper container manufacturing equipment 200> Next, with reference to Figures 5 to 10, the paper container manufacturing apparatus 200 in this embodiment will be described. More specifically, the paper container manufacturing apparatus 200 in this embodiment is composed of a clamping plate 210, an application roller section 220, a drying device 230, a slitting plate 240, a side support member 250, and a lower holding section 260. The paper container manufacturing apparatus 200 is configured to impregnate at least a portion of the end faces of the blank bundle 40 with an oil-resistant agent via an oil-resistant agent application roller 221 while the blank bundle 40 is pressed and clamped by the clamping plate 210, which will be described later.

[0036] In other words, in order to form an oil-resistant impregnation region RA on one side end 32 of the paper substrate 30 described above, in this embodiment, a plurality of paper substrates 30 are stacked to form a blank bundle 40, and the oil-resistant agent is impregnated onto the side surface of this blank bundle 40 via an oil-resistant agent application roller 221.

[0037] As illustrated in Figure 9, such a blank bundle 40 consists of a main surface 41 (one main surface 41A, the other main surface 41B) that is clamped by the clamping plate 210, an end surface 42 on the side to which the oil-resistant agent is applied corresponding to one of the lateral ends 32 of the paper substrate 30, the other end surface 43 corresponding to the other lateral end 33, the long side surface 44 corresponding to the long side end 34, and the short side surface 45 corresponding to the short side end 35.

[0038] This enables the simultaneous impregnation of multiple paper substrates 30 with an oil-resistant agent, significantly improving the productivity of the body section 20. The number of paper substrates 30 constituting the blank bundle 40 is not particularly limited, as long as the blank bundle 40 can be clamped by the clamping plate 210 to form an appropriate oil-resistant agent impregnation area RA. For example, several hundred to about 2,000 paper substrates 30 may be stacked.

[0039] As shown in Figure 5, the clamping plate 210 is composed of a first clamping plate 210A capable of pressing one main surface 41A of the blank bundle 40, and a second clamping plate 210B capable of pressing the other main surface 41B. The blank bundle 40 is clamped between the first clamping plate 210A and the second clamping plate 210B under a predetermined pressure.

[0040] As shown in Figures 6 and 8, the coating roller section 220 is composed of an oil-resistant coating roller 221 for applying oil-resistant agent to the blank bundle 40, a known roller rotation motor 222 for rotating the oil-resistant coating roller 221, a rotating shaft 223 for transmitting power from the roller rotation motor 222 to the oil-resistant coating roller 221, a support base 224 for supporting the oil-resistant coating roller 221 and the roller rotation motor 222, and an oil-resistant agent container 225 supported by the support base 224 for supplying oil-resistant agent to the oil-resistant coating roller 221.

[0041] As for specific examples of the oil-resistant coating roller 221, there are no particular limitations as long as it can apply the oil-resistant agent to the blank bundle 40. For example, various known resin rollers such as acrylic rollers, polyester rollers, or urethane rollers, or metal rollers can be used. Furthermore, as will be described later, a known oil-resistant agent RM (see Figure 11) is stored in the oil-resistant container 225 so as to be in contact with the coating surface of the oil-resistant coating roller 221.

[0042] The drying device 230 is configured to perform a drying treatment on the end faces of the blank bundles 40 that have been impregnated with the oil-resistant agent. As shown in Figure 6, the drying device 230 in this embodiment is mounted on the holding base 262 of the lower holding unit 260, which will be described later, together with the coating roller unit 220. Therefore, as the holding base 262 moves below the slit plate 240 on which the blank bundles 40 are mounted, the oil-resistant agent coating roller 221 and the drying device 230 can slide together with respect to the end faces of the blank bundles 40.

[0043] In this embodiment, the drying apparatus 230 performs a process of blowing dry hot air onto the end faces of the blank bundles 40 via a known heater, as an example. In addition to blowing dry air, the drying apparatus 230 may also use a known non-contact heating and drying device, such as an infrared heating device, or it may use a combination of dry air and infrared heating to dry the end faces of the blank bundles 40 coated with oil-resistant agent.

[0044] As can be seen from Figures 5, 6, 9, and 10, the slit plate 240 is configured to support the end faces of the blank bundle 40. The slit plate 240 is provided with an opening OP. This makes it possible to apply an oil-resistant agent to the end faces of the blank bundle 40, which are exposed through the opening OP of the slit plate 240, while the blank bundle 40, which is clamped by the clamping plate 210, is placed on the slit plate 240, and then dry them. In this embodiment, the width of the opening OP may be adjustable to any size, for example, via a sliding plate and a motor that can move the sliding plate.

[0045] The side support member 250 is configured to support the short side surface 45 of the blank bundle 40 when the end face of the blank bundle 40 is supported on the slit plate 240. As shown in Figure 9 and other figures, the side support member 250 of this embodiment is configured to include a first side support member 250A that can support the upper side of the short side surface 45 when the end face 42 is supported on the slit plate 240, and a second side support member 250B that can support the lower side of the short side surface 45. This allows the end face 42 of the blank bundle 40 to be coated with an oil-resistant agent to be stably placed on the slit plate 240.

[0046] A specific example of the side support member 250 is a known metal shaft as shown in the figure. In this embodiment, two metal shafts are used as the side support member 250, but for example, the short side surface 45 may be supported by one metal shaft, or by three or more metal shafts.

[0047] The lower holding portion 260 has the function of integrally holding the oil-resistant coating roller 221 and the drying device 230 and sliding (moving) them under the opening OP of the slit plate 240. More specifically, the lower holding portion 260 of this embodiment is composed of a drive mechanism 261 and a holding base 262. The drive mechanism 261 is composed of a known drive motor or the like. The holding base 262 holds the drying device 230 and is connected to the support base 224 described above via known fixing means such as bolts. The holding base 262 is configured to slide under the opening OP of the slit plate 240 by the drive mechanism 261 described above.

[0048] <Manufacturing method for paper containers> Next, a method for manufacturing paper containers in this embodiment using the paper container manufacturing apparatus 200 described above will be explained. The manufacturing method of this embodiment is a method for manufacturing a paper container comprising a bottom plate 10 and a peripheral wall-shaped body portion 20 rising from the periphery of the bottom plate 10, and comprises the following steps.

[0049] First, a process is carried out to form the paper substrate 30 that constitutes the blank bundle 40. As an example, the resin material may be laminated onto general paper of a predetermined size suitable for paper containers, and then cut into the known fan shape using a known cutting machine to form a paper substrate 30 with the resin layer LM laminated on one side. The method for forming the paper substrate 30 is not limited to the above, and other known methods may be applied.

[0050] Next, a step is performed to form a blank bundle 40 by stacking multiple fan-shaped paper substrates 30 that will form the body 20. More specifically, the blank bundle 40 may be formed by stacking multiple paper substrates 30 via a robot arm (not shown), for example. Alternatively, the blank bundle 40 of this embodiment may be formed by extracting a predetermined number of paper substrates 30 from a pre-stacked bundle via a robot arm or the like.

[0051] Next, a step is performed to clamp the blank bundle 40 with the clamping plates 210. More specifically, the blank bundle 40 is delivered onto the slit plate 240 between the pair of clamping plates 210, for example via a robot arm, and then the blank bundle 40 is clamped by the clamping plates 210 by pressing one main surface 41A and the other main surface 41B of the blank bundle 40 through the pair of clamping plates 210.

[0052] If the clamping pressure on the blank bundle 40 is weak, the oil-resistant agent may unintentionally penetrate from the overlapping portion of the blank bundle, making stable coating difficult. Therefore, the clamping load by the clamping plate 210 in this embodiment should be, for example, 0.004 N / mm². 2 The above is 2.747 N / mm 2 The following is preferable (when constructing a blank bundle 40 using approximately 800 to 1200 sheets of paper substrate 30 having a normal thickness (approximately 200 to 300 μm)).

[0053] In this embodiment, the end faces 42 of the blank bundle 40 are placed on the slit plate 240 while the blank bundle 40 is held between the clamping plates 210. As described above, it is preferable that the short side faces 45 of the blank bundle are supported by the side support members 250 when the end faces 42 of the blank bundle 40 are supported on the slit plate 240 (see Figure 9, etc.). Furthermore, in this embodiment, it is preferable that the surface of the clamping plate 210 on the side of the end face 42 is not flush with the end face 42, but rather that the surface of the clamping plate 210 on the side of the end face 42 is located about 1 mm above the end face 42. This suppresses interference between the oil-resistant coating roller 221 and the clamping plate 210 when applying the oil-resistant coating.

[0054] Next, a step is performed to impregnate the end faces of the blank bundle 40 with an oil-resistant agent. More specifically, while the blank bundle 40 is pressurized by the clamping plate 210 described above, at least a portion of the end faces 42 of the blank bundle 40 is impregnated with the oil-resistant agent via the oil-resistant agent application roller 221. At this time, while the blank bundle 40 is pressurized by the clamping plate 210, it is preferable to place the end faces 42 of the blank bundle 40 on a slit plate 240 with an opening OP formed therein, and impregnate at least a portion of the end faces 42 with the oil-resistant agent via the slit plate 240 using the oil-resistant agent application roller 221 while the end faces 42 are exposed through the opening OP. In this embodiment, since the oil-resistant agent application roller 221 is brought into contact with the end faces 42 to be coated only during application, wear of the oil-resistant agent application roller 221 can be reduced. In addition, in order to ensure even coating, it is preferable that the pressure at which the oil-resistant agent application roller 221 is brought into contact with the end faces 42 and the rotational speed of the oil-resistant agent application roller 221 during coating are approximately uniform. By using a roller to apply the oil-resistant agent in this way, handling is made easier while efficiently applying the oil-resistant agent to the necessary areas.

[0055] Following the application of the oil-resistant agent described above, a drying process is performed on the end faces 42 of the blank bundle 40, which have been impregnated with the oil-resistant agent, via a drying device 230. At this time, it is preferable to slide the oil-resistant agent application roller 221 and the drying device 230 in parallel against the end faces 42 of the blank bundle 40 so that the oil-resistant agent is impregnated onto the end faces 42 of the blank bundle 40 via the oil-resistant agent application roller 221, and then the end faces 42 are dried via the drying device 230 (see Figure 11, etc.). This makes it possible to stably impregnate the end faces 42 of the blank bundle 40 with the oil-resistant agent.

[0056] Furthermore, in the manufacturing method of the paper container in this embodiment, the configuration of the oil-resistant coating roller 221 and the drying device 230 when sliding the oil-resistant coating roller 221 and the drying device 230 under the opening OP may be varied. More specifically, the driving state of the oil-resistant coating roller 221 and the drying device 230 during the forward pass when moving under the opening OP in a first direction (positive X direction) may be made different from the driving state of these during the return pass when moving under the opening OP in a second direction (negative X direction).

[0057] In other words, in this embodiment, as shown in Figure 11, in the forward stroke, the oil-resistant coating roller 221 and the drying device 230 are slid in the first direction passing directly below the end face 42, and the oil-resistant coating roller 221 may be used to apply and dry the oil-resistant coating to the end face 42. As shown in the figure, the coating surface of the oil-resistant coating roller 221 is in contact with the oil-resistant coating RM stored in the oil-resistant coating container 225, and as the oil-resistant coating roller 221 rotates during the sliding motion, the oil-resistant coating RM is constantly supplied to the coating surface of the oil-resistant coating roller 221. On the other hand, in the return process, in which the oil-resistant coating roller 221 and the drying device 230 are slid in a second direction opposite to the first direction described above, the drying device 230 may be driven with the oil-resistant coating roller 221 at least separated from the end face so that drying is performed by the drying device 230 without applying the oil-resistant coating. More specifically, in the return process, as shown in Figure 11, the oil-resistant coating roller 221 is positioned at a distance h below the end face 42 compared to the forward process, and in this state, the oil-resistant coating roller 221 and the drying device 230 are slid in the second direction. In this embodiment, it is preferable that the drying time in the return process is longer than the drying time in the forward process.

[0058] Next, after the drying process described above, the paper substrate 30, which has been impregnated with the oil-resistant agent at one side end 32, is separated from the blank bundle 40, and the side ends of the separated paper substrates 30 are fixed together to form the body portion 20. As described in detail with reference to Figures 3 and 4, an oil-resistant impregnation region RA is formed at one side end 32 of the paper substrate 30 constituting the body portion 20 that has undergone the manufacturing method of the paper container in this embodiment, in which the oil-resistant agent has been impregnated.

[0059] Such oil-resistant impregnation region RA is formed to extend from one lateral end 32 to the other lateral end 33 within the side seam region SS. As shown in Figure 4, within the side seam region SS, the oil-resistant impregnation region RA is inclined such that the impregnation width from one lateral end 32 increases from the inner circumferential surface in the thickness direction of the paper substrate 30.

[0060] After the body portion 20 is formed by the method described above, the lower end of the body portion 20 and the bottom plate 10 are fixed together by a known method, including the patent document described above, and the upper end of the body portion 20 is curled to form the top curl portion described above. The paper container 100 of this embodiment is manufactured through the above steps.

[0061] According to the paper container, manufacturing apparatus, and manufacturing method described above in this embodiment, it is possible to reduce the amount of oil resistant agent used and suppress costs, while eliminating uneven application and efficiently impregnating the necessary areas (for example, within the range that fits within the side seam area, excluding the upper and lower ends such as the top curl portion) with the oil resistant agent. The embodiments described above are merely examples that embody the spirit of the present invention, and may be modified as appropriate without departing from the spirit of the present invention. Furthermore, known structures and methods may be added and modified as appropriate without departing from the spirit of the present invention.

[0062] <Variation> A modified paper container will be described below with reference to Figure 12. In the embodiment described above, a paper substrate 30 was used in which the resin layer LM was laminated to one side (one main surface 31A). In contrast, the main feature of this modified example is that a paper substrate 30 is used in which the resin layer LM is laminated to both the front and back surfaces (one main surface 31A and the other main surface 31B).

[0063] Figure 12 schematically shows the end of the body portion 20 laminated with the resin layer LM in the modified example described above. As can be seen from the figure, in this modified example, the resin layer LM is laminated to the inner circumferential surface (one main surface 31A) of the paper substrate 30, which will later become the inner surface of the paper container 100, and to the outer circumferential surface opposite to the inner circumferential surface (the other main surface 31B). An oil-resistant impregnation region RA, which is impregnated with the oil-resistant agent described above, is formed at one of the lateral ends 32 of the paper substrate 30.

[0064] In this modified example, the oil-resistant impregnation region RA is formed to extend from one lateral end 32 to the other lateral end 33 within the side seam region SS, but the distribution of the oil-resistant agent in the thickness direction differs from that of the above embodiment. Specifically, in the oil-resistant impregnation region RA of this modified example, the impregnation width of the oil-resistant agent from one lateral end 32 is sloped in the thickness direction of the paper substrate 30 so that it increases from the inner and outer circumferential surfaces towards the center.

[0065] In this modified example, since a resin layer LM is formed on both the front and back surfaces of the paper substrate 30, a certain degree of oil resistance is ensured, making it possible to efficiently apply the oil-resistant agent to the minimum necessary area. Even in this modified example, it is possible to achieve the same effects as in the above-described embodiment. [Industrial applicability]

[0066] This invention can be used, for example, in the manufacture of paper containers that can reduce the amount of oil-resistant agent used, thereby controlling costs and eliminating uneven coating. [Explanation of symbols]

[0067] 100 paper containers 10 Bottom plate 20 Torso 30 Paper base material 40 Blank Bundles 200 Paper container manufacturing equipment 210 Holding plate 220 Coating roller section 230 Drying equipment 240 Slit Plate 250 Side support member 260 Lower holding part

Claims

1. A method for manufacturing a paper container comprising a bottom plate and a peripheral wall-shaped body portion rising from the periphery of the bottom plate, The process of forming a blank bundle by stacking multiple fan-shaped paper substrates that will form the body, The process involves clamping the blank bundle with the clamping plates by pressing one main surface of the blank bundle against the other main surface of the blank bundle via a pair of clamping plates, The process involves applying pressure to the blank bundle with the clamping plate, and then impregnating at least a portion of the end faces of the blank bundle with an oil-resistant agent via an oil-resistant agent application roller. A step of drying the end face of the blank bundle impregnated with the oil-resistant agent using a drying device, After the drying process, the paper substrate impregnated with the oil-resistant agent at its lateral end is separated from the blank bundle, and the lateral ends of the separated paper substrates are fixed together to form the body portion. A method for manufacturing a paper container, characterized by including the following:

2. The oil-resistant agent comprises an oil-resistant resin component, water, and alcohol. A method for manufacturing a paper container according to claim 1, wherein the ratio of the alcohol to the oil-resistant resin component is adjusted so that the surface tension of the oil-resistant agent is 19.2 to 30.3 mN / m.

3. A method for manufacturing a paper container according to claim 1, wherein the oil-resistant coating roller and the drying device are slid in parallel against the end face of the blank bundle, thereby impregnating the end face with the oil-resistant coating roller, and then drying the end face with the drying device.

4. A forward process involves sliding the oil-resistant coating roller and the drying device in a first direction passing directly below the end face to apply and dry the oil-resistant agent to the end face using the oil-resistant coating roller. A method for manufacturing a paper container according to claim 3, comprising a return step of sliding the oil-resistant coating roller and the drying device in a second direction opposite to the first direction while moving the oil-resistant coating roller away from the end face, thereby drying by the drying device without applying the oil-resistant agent.

5. A method for manufacturing a paper container according to any one of claims 1 to 4, wherein the blank bundle is pressed with the clamping plate, the end face of the blank bundle is placed on a slit plate having an opening, and the oil-resistant agent is impregnated into at least a portion of the end face using the oil-resistant agent application roller through the slit plate while the end face is exposed through the opening.

6. The method for manufacturing a paper container according to claim 5, wherein the blank bundle is supported by a side support member when the end face of the blank bundle is supported on the slit plate.

7. The base plate and It has a side seam region formed by overlapping and joining one side end of a fan-shaped paper substrate to the other side end, and a peripheral wall-shaped body portion rising from the periphery of the bottom plate, A paper container equipped with, On one of the lateral ends located on the inner surface side of the body, an oil-resistant impregnation region is formed, having a concentration gradient of the oil-resistant agent from one lateral end toward the other lateral end. A paper container characterized by the following features.

8. The paper container according to claim 7, wherein the oil-resistant impregnation region is formed in such a way that the impregnation width of the oil-resistant agent from one of the side ends does not exceed the side seam region.

9. A resin layer is laminated to the inner circumferential surface of the aforementioned paper substrate, which is the inner surface side. The paper container according to claim 8, wherein the impregnation width from one of the side ends is inclined such that it increases from the inner surface to the outer surface in the thickness direction of the paper substrate.

10. A resin layer is laminated to the inner circumferential surface of the paper substrate that is on the inner side and to the outer circumferential surface opposite to the inner circumferential surface. The paper container according to claim 8, wherein the impregnation width from one of the lateral ends is inclined in the thickness direction of the paper substrate such that it increases from the inner circumferential surface and the outer circumferential surface towards the center.

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