Lid

Abstract

To ensure strength for a lid body three-dimensionally molded by a pulp mold manufacturing method.SOLUTION: A lid body 10A that is three-dimensionally molded by a pulp mold manufacturing method is attached to a bottomed cylindrical container 5. The lid body 10A comprises: a top lid part 20A for covering an opening of the container 5; and a peripheral edge part 30, which is provided on a peripheral edge of the top lid part 20A, and attached to an opening end 5A of the container 5. The top lid part 20A in a state of being attached to the container 5 is molded into a dome shape swollen outward in a direction separating from the container 5.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a lid body three-dimensionally molded by a pulp molding method.

Background Art

[0002] As a lid body for closing the opening of a bottomed cylindrical container such as a paper cup, a lid body three-dimensionally molded by a pulp molding method (made of pulp molding) is known (for example, see Patent Document 1 below). In the lid body of Patent Document 1, the central portion of the lid body is formed so as to protrude in a substantially cylindrical shape, and the substantially cylindrical portion mainly covers the opening of the container.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A lid body made of pulp molding is more difficult to ensure strength than a lid body made of plastic, and tends to be deformed by an external force. For example, in the case of the lid body of Patent Document 1, particularly in the central portion protruding in the substantially cylindrical shape described above, a flat surface is likely to be deformed by an external force, so that the strength tends to be insufficient. Therefore, there was room for improvement in ensuring the strength of a lid body made of pulp molding.

[0005] The present case was created in view of the above problems, and one of the objectives is to ensure the strength of a lid body three-dimensionally molded by a pulp molding method. Note that, not limited to this objective, the actions and effects derived from each configuration shown in the "Mode for Carrying Out the Invention" described later, and the actions and effects that cannot be obtained by the conventional technology can also be positioned as other objectives of the present case.

Means for Solving the Problems

[0006] The lid disclosed herein comprises a top portion that covers the opening of a bottomed cylindrical container, and a peripheral portion provided on the periphery of the top portion and attached to the opening end of the container, and is a lid that is three-dimensionally molded by a pulp molding method, wherein the top portion is molded into a dome shape that bulges in a direction away from the container when attached to the container. [Effects of the Invention]

[0007] According to this case, strength can be ensured by a lid that is three-dimensionally molded using the pulp molding method. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view of the lid of the first embodiment. [Figure 2] Figure 1 is a front view of the lid. [Figure 3] Figure 1 is a plan view of the lid. [Figure 4] This is a cross-sectional view taken along arrow AA in Figure 3. [Figure 5] (a) to (c) are explanatory diagrams illustrating curvature. [Figure 6] This is a perspective view of the lid of the second embodiment. [Figure 7] Figure 1 is a perspective view showing another example of the lid. [Figure 8] This is a perspective view showing yet another example of the lid in Figure 1. [Modes for carrying out the invention]

[0009] The following describes the embodiments for implementing this invention. The embodiments described below are merely examples, and there is no intention to exclude various modifications or applications of technologies not explicitly stated in these embodiments. Each configuration of this embodiment can be modified in various ways without departing from its spirit. Furthermore, components can be selected and combined as needed.

[0010] [A. Overview of the First and Second Embodiments] The lids of the first and second embodiments are made primarily from pulp and are three-dimensionally molded using the pulp molding method (also written as pulp mold). These molded (also referred to as shaped) pulp molded lids are made from natural materials, making them an eco-friendly product. Section "A" describes the pulp used for the lids mentioned above, and an example of the manufacturing method for the lids.

[0011] <Pulp raw materials> Examples of pulp raw materials for this cap include wood pulp, non-wood pulp, and mixed pulp of wood pulp and non-wood pulp. Wood pulp generally refers to wood pulp used in papermaking, and is classified into chemical pulps such as kraft pulp (KP), sulfite pulp (SP), and soda pulp (AP) based on the preparation method; semi-chemical pulps such as semi-chemical pulp (SCP) and chemigland wood pulp (CGP); and mechanical pulps such as crushed wood pulp (GP), thermomechanical pulp (TMP, BCTMP), and refiner-ground wood pulp (RGP). Examples of wood pulp include coniferous pulp and hardwood pulp, depending on the raw materials. Non-wood pulp is fiber extracted from the bark, stems, leaves, and leaf sheaths of plants.

[0012] When the pulp raw material is a mixed pulp of wood pulp and non-wood pulp, the wood pulp content in the pulp raw material is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, even more preferably 20% by mass or more, even more preferably 45% by mass or more, and preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 80% by mass or less, and even more preferably 55% by mass or less.

[0013] Non-wood pulp is fibers collected from the bark, stems, leaves, and leaf sheaths of plants. Specifically, it includes pulp obtained from cotton linter, cotton, linen, hemp, ramie, straw, esparto, manila hemp, sisal hemp, jute, flax, kenaf, bamboo, bagasse, ganpi, mitsumata, kozo, and mulberry. From the perspective of improving the oil resistance of the lid, it is preferable that the non-wood pulp contains at least one selected from bagasse and bamboo pulp, more preferably at least one selected from bagasse and bamboo pulp, and even more preferably bagasse. From the perspective of obtaining a lid that is difficult to deform (i.e., has a high modulus of elasticity) even under an external force, it is preferable to contain at least one of bagasse pulp and softwood pulp. At this time, the content of bagasse pulp or softwood pulp (when both pulps are included, the total content) relative to the total amount of pulp is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 75% by mass or more, and even more preferably 85% by mass or more (upper limit: 100% by mass). From the perspective of obtaining a lid with excellent smoothness, it is preferable to blend hardwood pulp. Specifically, the content of hardwood pulp relative to the total amount of pulp is preferably 15% by mass or more, more preferably 30% by mass or more (upper limit: 100% by mass).

[0014] The pulp raw material preferably contains 80% by mass or more of virgin pulp. By setting the content of virgin pulp to 80% by mass or more, a lid with better surface smoothness can be obtained. The content of virgin pulp in the pulp raw material is more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 98% by mass or more (upper limit: 100% by mass). In particular, when used for beverage containers, it is difficult to ensure the traceability of harmful substances contained in pulp raw materials other than virgin pulp (such as waste paper), so it is preferable that the virgin pulp in the pulp raw material is 100% by mass. The virgin pulp is not particularly limited, but for example, sun-dried pulp and semi-sun-dried pulp are preferable.

[0015] In addition, unbleached pulp has a large residual amount of lignin, low whiteness, and tends to be inferior in decorativeness. Therefore, the content of unbleached pulp in the pulp raw material is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, and even more preferably not contained (0% by mass). Also, when containing mercerized pulp or crosslinked pulp as the pulp raw material, the strength of the lid body tends to decrease or the density tends to decrease. Therefore, the content of mercerized pulp and crosslinked pulp in the pulp raw material is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, and even more preferably not contained (0% by mass), respectively. On the other hand, in applications where strength, inconspicuousness of dirt, and a natural texture are required, it is preferable to use unbleached pulp. At this time, the content of unbleached pulp in the pulp raw material is preferably more than 20% by mass, more preferably 50% by mass or more, still more preferably 80% by mass or more (upper limit 100% by mass). In this case, at least one of bleached pulp and semi-bleached pulp may be used in combination with unbleached pulp.

[0016] Recycled pulp has a large residual amount of ink and tends to be inferior in dispersibility. Also, the fibers of recycled paper tend to have fluff and be deformed. In addition, recycled pulp has low whiteness, and there are unbleached fibers that remain on the pulp fibers and appear long and black, and tend to generate black whiskers. Also, due to the presence of vinyl or the like that appears gray or black spot spots remaining, chills can be seen. As a result, the appearance and surface smoothness of the obtained lid body tend to decrease. Therefore, the content of recycled pulp in the pulp raw material is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, and even more preferably not contained (0% by mass).

[0017] In this case, the Canadian standard filtration density of the pulp raw material is preferably 100 mL or more, more preferably 150 mL or more, and even more preferably 200 mL or more, from the viewpoint of productivity of the pulp raw material and papermaking properties when manufacturing the lid, and from the viewpoint of surface smoothness, it is preferably 700 mL or less, more preferably 650 mL or less, even more preferably 600 mL or less, even more preferably 520 mL or less, even more preferably 450 mL or less, even more preferably 400 mL or less, and even more preferably 300 mL or less. The degree of beating should be adjusted so that the Canadian standard filtration rate falls within the above range. Canadian standard filtration capacity is measured in accordance with JIS P 8121-2:2012.

[0018] <Other ingredients> The lid is formed primarily from the pulp mentioned above. The lid may be made from 100% pulp, but other materials such as various internal additives can be added in addition to the pulp. Other components include inorganic substances such as talc and kaolin, inorganic fibers such as glass fibers and carbon fibers, synthetic resin powders or fibers such as polyolefins, polysaccharides such as carboxymethylcellulose, sizing agents, wet strength enhancers, dry strength enhancers, oil resistant agents, yield enhancers, water filtration enhancers, bulk enhancers, aluminum sulfate, pH adjusters, pitch control agents, slime control agents, and colorants such as pigments. It is preferable to include a sizing agent as another component.

[0019] Examples of sizing agents include rosin-based sizing agents (e.g., acidic rosin-based sizing agents, neutral rosin-based sizing agents), alkyl ketene dimers, alkenyl succinic anhydride, and styrene-(meth)acrylate copolymers, with alkyl ketene dimers being preferred.

[0020] Examples of wet-strength enhancers for internal additive use include polyamidoamine-epichlorohydrin resin, epoxidized polyamide polyamine, dialdehyde starch, urea-formaldehyde resin, melamine-formaldehyde, polyacrylamide, methylolated polyacrylamide, and polyethyleneimine. Examples of water-repellent agents include wax emulsions, metal soaps (alkali salts of sodium, potassium, zinc, lithium, magnesium, etc.), fatty acid chromium complex salts (myristic complex salts, chromic chloride stearate complex salts, etc.), zirconium water-repellent agents, and silicone emulsions.

[0021] When this lid contains non-wood pulp, it is possible to improve oil resistance using only pulp raw materials. Therefore, sufficient oil resistance can be obtained even if the amount of wet strength enhancer and water repellent added is reduced or eliminated. However, this does not preclude the addition of wet strength enhancer or water repellent for the purpose of obtaining higher oil and water resistance.

[0022] The lid may be constructed in multiple layers by performing the papermaking process described later multiple times or by hot-pressing multiple mold intermediates in the hot-pressing process, but it is preferable to have a single-layer structure from the viewpoint of superior surface smoothness and oil resistance.

[0023] The container is not particularly limited as long as it can hold the contents, but it is preferably a food container or a beverage container, and more preferably a beverage container. Examples of beverage containers include cups made of plastic (for example, thermoplastic resins such as PET (e.g., C-PET), PP, PE, PS; biodegradable plastics; natural material mixed plastics), polystyrene foam, and paper (e.g., cardboard, pulp mold), and paper cups are more preferably paper cups. The container is preferably such that the opening end has an outward-curling shape.

[0024] <Secondary processing lid> This lid may be surface-treated to become a secondary processed lid. The lid of the present invention includes secondary processed lids. A secondary processed lid is a lid that has been surface-treated. Furthermore, this lid has the advantage of being easy to surface-treat because it has excellent surface smoothness. The method of secondary processing is not particularly limited, and is not limited to any method that can surface-process the pulp mold. However, the secondary processed lid is preferably surface-processed by at least one of the following surface processing methods: direct printing, lamination, transfer, and vapor deposition. It is more preferably surface-processed by at least one of the following surface processing methods: direct printing, lamination, and transfer. It is even more preferably surface-processed by at least one of the following surface processing methods: lamination and transfer. It is even more preferably surface-processed by at least one of the following surface processing methods: vacuum lamination and hot stamp transfer, as described later. However, the method is not limited to these; pre-printed stickers or similar labels may also be attached.

[0025] (Direct printing method) Direct printing is a method of applying ink or resin directly to the surface of a lid for the purpose of imparting color, patterns, designs, etc., or providing properties such as waterproofing and moisture resistance. This method also includes surface processing of the lid by impregnation, printing, etc. The printing method can be any of the following: relief printing using rubber or resin plates, screen printing, pad printing, electrostatic printing, or thermal transfer printing. The printed surface of the lid can then be given a design, text, or other pattern.

[0026] Alternatively, the lid may be directly coated with a brush or spray. Among these methods, spray coating is preferred from the viewpoint of uniformly applying the resin. Spray coating may be performed using an air spray, airless spray, electrostatic spray, or any other method. To provide waterproofing or moisture resistance to the surface of the lid, a water-based emulsion paint containing resins such as acrylic resin, styrene resin, urethane resin, melamine resin, olefin resin, epoxy resin, polyvinyl alcohol resin, or vinylidene chloride resin as solid components, or an aqueous solution paint or organic solvent-based paint of these resins, may be applied.

[0027] (Lamination method) Lamination is preferably carried out by coating with a resin film. Examples of resin films that can be used include polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyamide resins such as nylon; polyvinyl resins such as polyvinyl chloride; styrene resins such as polystyrene; thermoplastic resin films such as ethylene-vinyl alcohol copolymer and polyacrylonitrile; and biodegradable resin films such as modified polyethylene terephthalate and aliphatic polyester. Considering manufacturing costs and moldability, polyolefin resins are preferred, and from the viewpoint of environmentally friendly disposal, biodegradable resin films are preferred. Lamination may also be formed by laminating two or more of these resin films. The thickness of the resin film is not particularly limited, but it is preferably between 10 μm and 300 μm.

[0028] By laminating the above-mentioned resin film, functions such as water resistance, oil resistance, and gas barrier properties can be improved or imparted. Furthermore, the resin film to be laminated may have a design printed on it beforehand, and coloring pigments, fine particles (pearl pigments, holograms, etc.), luminous dyes, luminous pigments, etc. may be added. By using such a resin film, gloss and design can be imparted to the surface of the lid.

[0029] Lamination can be performed on the lid using known methods such as extrusion lamination, heat lamination, dry lamination, or wet lamination. Among these, thermal lamination is preferred, vacuum lamination and vacuum pressing are preferred, and vacuum lamination is more preferred. Vacuum lamination may be performed by deforming a sheet placed on top of the substrate (pulp mold side) by suction from the substrate side (pulp mold side) to perform lamination, or by dividing the upper and lower chambers, which are pre-vacuumed, into two parts with a resin film, and applying compressed air to the upper chamber equipped with a resin film heating device to laminate the substrate (lid) placed in the lower chamber. Furthermore, vacuum pressing deforms silicone rubber or similar material into the shape of the base material by applying vacuum suction from the base material (lid) side, and in some cases, compressed air from above. The resin film sandwiched between the silicone rubber and the base material is then laminated to the base material by the pressure of the silicone rubber. Alternatively, the resin film may be pre-formed using a mold to match the shape of the lid, and then laminated to the lid.

[0030] Lamination can be carried out using conventionally known methods, and examples of vacuum lamination equipment include the TOM molding machine (manufactured by Fuse Vacuum Co., Ltd.). Furthermore, the temperature, pressure, and other conditions during lamination should be appropriately selected depending on the material and thickness of the resin film to be laminated, the shape of the substrate, and the presence or absence of adhesive. For example, the heating temperature of the heater should be between 80°C and 200°C when lamination is performed.

[0031] During lamination, an adhesive may or may not be applied between the resin film and the lid. Suitable adhesives include polyurethane adhesives, polyacrylic adhesives, polyester adhesives, epoxy adhesives, polyvinyl acetate adhesives, cellulose adhesives, and other laminating adhesives. If an adhesive is used, coloring pigments, pearl pigments, fine particles (such as holograms), phosphorescent pigments, phosphorescent dyes, etc., may be added to the adhesive.

[0032] (Transmission method) Examples of transfer methods include hot stamping transfer, in-mold transfer, and water transfer, and either dry or wet transfer methods may be used. In addition, a pre-molding step may be added to the in-mold transfer method. Among the transfer methods, the hot stamping transfer method (hereinafter also simply referred to as the "hot stamping method") is preferred. The hot stamping method is a method that uses a film coated with metal or pigment, called a "foil," and heat-transfers it to a substrate via a heat-adhesive layer provided on the surface of the foil. The foil used in the hot stamping method is laminated in the following order: a release-type base film (for example, a biaxially oriented polyester film), a release layer (protective layer), a pattern layer or vapor-deposited layer, and a heat-adhesive layer. If necessary, a release layer is provided between the base film and the protective layer. Examples of hot stamping methods include (i) the up-down method and (ii) the roll transfer method, and the principle is the same in which the pattern layer or vapor-deposited layer in the area where heat and pressure are present is transferred to the substrate (lid). In the up-down method, a mold plate with a built-in heater is pressed against the substrate from the base film side, and the pattern layer or vapor-deposited layer is transferred to the substrate via the heat-adhesive layer. Similarly, in the roll transfer method, the pattern layer or vapor-deposited layer is transferred to the substrate by pressing a heated roller from the base film side. Furthermore, by applying grinding, gloss treatment, or texture processing to the base film, it is possible to shape (create unevenness) the pattern layer and vapor-deposited layer during the transfer process.

[0033] (Vapor deposition) The vapor deposition can be any conventionally known vapor deposition method, and may be either physical or chemical vapor deposition; it is not particularly limited. However, it is preferable to perform the deposition for the purpose of imparting metallic luster to the lid, and vacuum vapor deposition, which is a type of physical vapor deposition, is more preferable. The vapor deposition material is preferably a metal such as aluminum, chromium, zinc, gold, silver, platinum, or nickel, or an oxide or fluoride such as SiO2, TiO2, ZrO2, or MgF2. The thickness of the deposited layer is not particularly limited, but it is preferably 0.1 μm or more.

[0034] <Method for manufacturing the lid> Various known methods for three-dimensionally molding pulp molds can be used as methods for manufacturing the above-mentioned lid. For example, the manufacturing methods described in Japanese Patent Publication No. 09-286468 and Japanese Patent Publication No. 07-42100 can be used.

[0035] For example, the lid is manufactured through the following steps 1 to 3. Step 1: Pulp suspension preparation step Step 2: Pulp is formed from the pulp suspension obtained in Step 1 via a papermaking machine. process Step 3: While heating the mold intermediate obtained in Step 2, the first press die and the first Hot pressing is performed using a second press die located in the opposite direction from the first press die. Hot pressing process

[0036] In step 1, a pulp suspension (pulp slurry) is prepared by adding pulp raw materials, sizing agents, and other additives. The concentration of the suspension (slurry concentration) is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, and preferably 7% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less, from the viewpoint of surface smoothness, dimensional stability, and productivity.

[0037] Step 2 is the papermaking process, in which pulp is formed from the pulp suspension via a papermaking mold. A molding die, such as a wire mesh mold with a vacuum-permeable structure, is immersed in a pulp suspension. The pulp suspension is drawn into the molding die to remove water, while the pulp fibers are laminated and adsorbed onto the die to form a three-dimensional wet paper symmetrical to the die. Then, the molding die is withdrawn from the pulp suspension, and the water-containing three-dimensional wet paper is dehydrated by suction or pressure.

[0038] In this process, the molding die, on which pulp has been layered and adsorbed onto its surface, is brought close to the pulp-adsorbed surface while vacuum suction is maintained. A release mold (release device) with vacuum suction is then brought close to the pulp-adsorbed surface, compressing and vacuum-suctioning the pulp mold intermediate to dewater it. After that, the vacuum pressure of the molding die is returned to atmospheric pressure, and the release mold is pulled back with the pulp mold intermediate still adsorbed onto it to release it.

[0039] Step 3 is a hot pressing step in which the mold intermediate obtained after the papermaking step is heated and hot-pressed using a first press die and a second press die located in the opposite direction from the first press die. Step 3 involves transferring the dewatered pulp mold intermediate obtained in Step 2 to a first press die for hot pressing, which is made of a porous mold, for example. The pulp mold intermediate transferred to the first press die is heated and pressurized by the first press die and a second press die for hot pressing, which is located in the opposite direction from the first press die and engages with the first press die, to obtain a predetermined lid.

[0040] Furthermore, it is preferable to incorporate an electric heater inside at least one of the first and second press dies for hot pressing, thereby heating at least one of the first and second press dies. Alternatively, the entire mold, including the first and second press dies, may be housed in a furnace into which hot air is introduced, so that hot air also passes through the inside of the mold.

[0041] In step 3 (hot pressing step), the pressure applied by the first and second press dies during pressing is preferably 0.1 MPa or higher, more preferably 0.3 MPa or higher, even more preferably 0.4 MPa or higher, and even more preferably 0.6 MPa or higher, from the viewpoint of obtaining a lid with excellent surface smoothness, and preferably 3.0 MPa or lower, more preferably 2.0 MPa or lower, and even more preferably 1.5 MPa or lower, from the viewpoint of power consumption and equipment load.

[0042] In step 3 (hot pressing step), the temperature during hot pressing is preferably 130°C or higher, more preferably 150°C or higher, and even more preferably 170°C or higher, from the viewpoint of obtaining a lid with excellent surface smoothness, and preferably 280°C or lower, more preferably 250°C or lower, and even more preferably 230°C or lower, from the viewpoint of power consumption, equipment load, and discoloration suppression.

[0043] The lid obtained as described above may be further processed by cutting off unnecessary parts and, if necessary, drilling holes to form, for example, at least one of a drinking spout and a notch.

[0044] For the manufacturing of this lid, it is preferable to employ the so-called "fine molding" method, from the viewpoint of achieving a smooth surface and ensuring surface quality to ensure a pleasant tactile experience for the user. For example, by pressurizing and drying at 120°C or higher in step 3 above, a lid with a well-defined surface can be manufactured. The lid molded in this way has excellent surface smoothness, resulting in a good appearance and no discomfort during use.

[0045] [B. First Embodiment] [B1. Structure] In the first embodiment, the structure of the lid is described in item "B1," and the parameters of the lid are described in item "B2." Then, the effects of items "B1" and "B2" are described in item "B3." In this embodiment, a lid attached to a paper cup is described as an example. In the following description, the vertical direction is defined based on the state in which the paper cup is placed on a horizontal surface. Furthermore, the direction toward the storage space of the paper cup is defined as "inside," and the opposite direction is defined as "outside."

[0046] The cover of the first embodiment will be described with reference to Figures 1 to 4. In describing this embodiment, we will mainly refer to Figure 1, which shows a perspective view of the lid 10A, and will omit reference numerals and specific mentions in Figures 2 to 4, which show the front view, plan view, and cross-sectional view of the lid 10A, as appropriate. The lid 10A of this embodiment is attached to the open end 5A of the paper cup 5 (shown by a dashed line in Figure 1), as shown in Figure 1, and is a lid that covers (closes) the opening of the paper cup 5. The lid 10A of this embodiment is three-dimensionally molded using the above-described method with the above-described pulp raw material.

[0047] Paper cup 5 is a cylindrical (bottomed tube) paper container. Examples of paper materials used for paper cup 5 include cardboard and pulp mold. The open end 5A is the upper end (opposite the bottom) of the paper cup 5. The opening of the paper cup 5 is the area enclosed by the open end 5A, and is the part where the internal storage space of the paper cup 5 communicates with the outside. The outer circumference of the open end 5A is preferably formed to be thick by an outward curling process.

[0048] The lid 10A comprises a top cover portion 20A and a peripheral edge portion 30. The top cover portion 20A is located in the center of the lid 10A and forms the part that covers the opening when the lid 10A is attached to the paper cup 5. The peripheral portion 30 is provided on the periphery of the top portion 20A and is a fitting portion that can be detachably fitted (attached) to the open end 5A of the paper cup 5. In this embodiment, the peripheral portion 30 is formed in an annular shape that follows the contour of the open end 5A of the paper cup 5. Therefore, the lid 10A is formed in a circular shape when viewed from above, as shown in Figure 3.

[0049] The canopy portion 20A is molded into a dome shape that bulges upward (in the direction away from the paper cup 5 when attached to the paper cup 5). Specifically, as shown in Figures 1 to 4, the canopy portion 20A of this embodiment has a dome shape that bulges upward in a hemispherical shape from the peripheral portion 30. In other words, the hemispherical dome shape that makes up the canopy portion 20A of this embodiment is a dome shape in which a curved surface is formed by continuous curved surfaces. The area inside the canopy portion 20A of this embodiment, that is, the area surrounded by the dome-shaped wall, is hollow. As shown in Figure 4, the shape of the cross-section of the canopy portion 20A along the vertical direction is an arc.

[0050] As shown in Figures 1, 2, and 4, the canopy portion 20A is subdivided into a side wall portion 22 and a top portion 24 in the vertical direction. The side wall portion 22 is a region that extends vertically along the canopy portion 20A. The top portion 24 is a region that extends along a direction that intersects the vertical direction along the canopy portion 20A. In the canopy portion 20A illustrated in Figures 1 to 4, the top portion 24 is the main body portion of the canopy portion 20A and is the main body portion that mainly covers the opening when attached to the paper cup 5. The side wall portion 22 is the part that forms the side wall of the canopy portion 20A and is erected from the inner circumference of the peripheral edge portion 30. In the canopy section 20A illustrated in Figures 1 to 4, the top section 24 is connected to the upper side of the side wall section 22 and forms a curved surface that bulges upward with the central section as the apex. This curved surface follows the shape of a sphere. The side wall portion 22 forms a curved surface that curves inward towards the inside of the paper cup 5 from the bottom to the top. In the lid portion 20A of this embodiment, the side wall portion 22 and the top portion 24 are integrally molded into a dome shape.

[0051] In this embodiment, it is preferable that the curved surface of the top portion 24 and the curved surface of the side wall portion 22 are formed with different curvatures. Specifically, it is preferable that the curvatures of the outer surfaces of the upper and lower cross-sections of the top portion 24 and the side wall portion 22 are different. By setting the curvatures of the top portion 24 and the side wall portion 22 individually in this way, the designability of the top portion 24 can be improved. Specifically, it is easier to improve the appearance of the canopy portion 20A, and for example, the less curvature there is (i.e., the closer the shape is to flat), the easier it is to mold the pattern 40 described later onto the top portion 24 in an uneven manner. In this embodiment, a structure in which the side wall portion 22 curves inward as it moves upward is illustrated as an example, but the shape of the upper and lower cross-sections of the side wall portion 22 may also be straight.

[0052] As shown in Figure 4, the peripheral edge 30 is provided with a fitting groove 32 that fits into the open end 5A of the paper cup 5. The fitting groove 32 illustrated here has an open U-shape on the bottom, as shown in Figure 4, and is formed around the entire circumference of the peripheral edge 30 in the circumferential direction. The inner wall portion 32B, which forms the inner wall surface in the interlocking groove 32, is connected to the lower end of the side wall portion 22 (canopy portion 20A) of the canopy portion 20A via the connecting portion 32C. The outer wall portion 32A, which forms the outer wall surface of the fitting groove 32, is positioned outside the outer circumference of the opening end 5A when attached to the paper cup 5, and is designed to catch on the outer circumference of the opening end 5A. This maintains the state in which the lid 10A is attached to the paper cup 5, and also prevents the paper cup 5 and the lid 10A from separating unintentionally by the user.

[0053] In this embodiment, a C-shaped notch 26 is formed in the central part of the top portion 24 of the canopy portion 20A. The opening formed by pushing the area surrounded by the C-shaped notch 26 inward functions as a straw insertion port. In addition, a predetermined pattern 40 is formed on the outer surface of the canopy portion 20A of this embodiment. The pattern 40 is a design formed with raised and recessed areas by a pulp molding process. In the lid 10 of this embodiment, a pattern based on a "finless porpoise" (animal) is given as an example of the predetermined pattern 40. By providing the predetermined pattern 40 on the canopy portion 20A, the design of the lid 10A can be enhanced. Note that the pattern is not limited to raised and recessed areas and may be formed by other methods (such as printing).

[0054] [B2.Parameters] Next, the parameters of the lid 10A in this embodiment will be described. <Thickness Dimensions> The thickness dimension of the canopy section 20A is the distance between the inward-facing surface and the outward-facing surface of the canopy section 20A. The thickness dimension is measured according to the following procedure A1 to A4. Procedure A1: Smoothly cut the canopy section 20A along the dashed line L1 in Figure 3 using a cutter. ru. Step A2: At the position cut in Step A1, expose the end face (cut surface) of the canopy section 20A. Let it.

[0055] Step A3: The thickness of the end face of the canopy portion 20A exposed in Step A2 is measured in the following three regions 1 Measure at ~3. The measurement will be performed using a digital microscope (HiRox). It was implemented using this method. • Area 1: The area enclosed by the cut portion 26 • Region 2: Any part of the top 24 excluding the cut portion 26 ·Area 3: Side wall part 22 Procedure A4: Use the five lids 10A to measure regions 1-3 according to procedures A1-A3 above. The measurement will be carried out. The average values ​​of regions 1-3 measured on the five lids 10A will be calculated. These dimensions were adopted as the dimensions for areas 1 to 3.

[0056] The thickness of the canopy portion 20A is preferably above a predetermined lower limit from the viewpoint of ensuring strength, and preferably below a predetermined upper limit from the viewpoint of suppressing drying costs and pulp usage. Specifically, the thickness dimension is preferably 0.3 mm or more and 2.0 mm or less, more preferably 0.5 mm or more and 1.5 mm or less, and even more preferably 0.8 mm or more and 1.2 mm or less.

[0057] <Curvature radius ratio> As shown in Figures 1 to 4, the curved surface of the apex 24 of the canopy portion 20A follows the shape of a sphere as described above. Therefore, the upper and lower cross-sections along the vertical direction of the apex 24 of the canopy portion 20A form an arc shape (see Figure 4). In this embodiment, the degree of curvature of the curved surface forming the apex 24 of the canopy portion 20A is defined by the "radius of curvature ratio". The radius of curvature ratio is a parameter that corresponds to the degree of curvature of the curved surface forming the apex 24. In this embodiment, the radius of curvature ratio is defined by the ratio of the radius R of the circle along the arc appearing in the upper and lower cross sections of the lid portion 20A to the inner diameter φ of the open end 5A of the paper cup 5, using the following formula 1. Curvature radius ratio=R / φ...Equation 1

[0058] The ratio of radii of curvature will be explained in detail using Figures 5(a) to 5(c). In Figures 5(a) to (c), "height H" is the distance between the lower end and the upper end of the canopy section 20A (20X, 20Y). "Height h" is the height dimension of the region with constant curvature on the curved surface of the canopy section 20A (20X, 20Y). In the canopy section 20A in Figure 5(a), height h is the distance from the lower end of the top section 24 (the boundary with the side wall section 22) to the upper end of the top section 24. The height h shall be such that its ratio to the height H of the canopy section 20A satisfies the following height ratio conditions. Height ratio condition: h > 0.4H and h ≤ H

[0059] Figure 5(a) shows the top portion 20A (top portion 24) of the lid 10A shown in Figures 1 to 4. In Figure 5(a), the circle C1 along the arc appearing in the upper and lower cross-sections of the top portion 20A is shown by a dashed line. The curvature of the canopy portion 20A (top portion 24) shown in Figure 5(a) is expressed by the ratio R / φ of the radius R of circle C1 to the inner diameter φ of the open end 5A [not shown in Figure 5(a)]. Figures 5(b) and 5(c) show lids 10X and 10Y with a modified height ratio relative to lid 10A. Note that lids 10X and 10Y in Figures 5(b) and 5(c) do not have the pattern 40, but they may have the pattern 40.

[0060] Figure 5(b) shows the lid 10X in which the height h of the top portion 24 is set to 0.4H (lower limit of the height ratio). In the top lid portion 20X of the lid body 10X, the side wall portion 22 has a straight shape in its upper and lower cross-section, and the angle of inclination of the side wall portion 22 toward the inside of the container is greater than that of the top lid portion 20A. The curvature of the canopy portion 20X (top portion 24) is expressed by the ratio of the radius R of the circle C2 (see dashed line) along the arc appearing in the upper and lower cross-sections of the canopy portion 20X to the inner diameter φ of the open end 5A (not shown in Figure 5(b)). The curvature of the canopy portion 20X is smaller than the curvature of the canopy portion 20A shown in Figure 5(a).

[0061] Figure 5(c) shows a lid 10Y in which height h is set to the same dimension as height H (upper limit of the height ratio). The canopy portion 20Y in Figure 5(c) can be described as having a structure in which the top portion 24 and the side wall portion 22 are not separated (a structure in which the curved surfaces of the top portion and the side wall portion 22 are uniform). The curvature of the canopy portion 20Y (top portion 24) is expressed by the ratio of the radius R of the circle C3 (see dashed line) along the arc appearing in the upper and lower cross-sections of the canopy portion 20Y to the inner diameter φ of the open end 5A (not shown in Figure 5(c)). The curvature of the canopy portion 20Y (top portion 24) is greater than the curvature of the canopy portion 20A (top portion 24) shown in Figure 5(a).

[0062] The curvature of the canopy sections 20A, 20X, and 20Y illustrated in Figures 5(a) to (c) is preferably above a predetermined lower limit and below a predetermined upper limit from the viewpoint of ensuring strength. Specifically, the curvature is preferably 0.32 or more and 0.56 or less, more preferably 0.35 or more and 0.51 or less, and even more preferably 0.38 or more and 0.46 or less.

[0063] [B3. Effects and Benefits] Since this embodiment is configured as described above, the following actions and effects can be obtained. The lid 10A, which is three-dimensionally molded using a pulp molding method, has a dome-shaped top section 20A that bulges upward (away from the paper cup 5) when attached to the paper cup 5. Because the top section 20A is dome-shaped, the structure is such that external forces applied to the top section 20A are easily dispersed. Therefore, the lid 10A can ensure greater strength compared to lids where the top section is formed as a flat surface (a shape other than a dome).

[0064] Since the side walls 22 and the top 24 that constitute the canopy 20A are integrally molded into a dome shape, strength can be ensured in either the side walls 22 or the top 24. Since the canopy section 20A is molded into a hemispherical dome shape formed by a continuous curved surface, when external force is applied, it is distributed across the entire surface of the canopy section 20A, thus ensuring strength. In addition, because the entire outer surface of the canopy section 20A has a continuous curved surface, it has a smooth feel to the touch.

[0065] Since the thickness dimension of the top cover 20A is 0.3 mm or more and 2.0 mm or more, the strength of the lid 10A can be improved. Furthermore, the weight can be suppressed while improving the strength of the lid 10A. Furthermore, the curvature of the curved surface of the canopy sections 20A, 20X, and 20Y, defined by the ratio of the radius of the circle along the arc appearing in the upper and lower cross-sections of the canopy sections 20, 20X, and 20Y to the inner diameter of the opening end, is 0.32 or greater and 0.56 or less, thus improving the strength of the lids 10A, 10X, and 10Y.

[0066] [C. Second Embodiment] The lid 10B of the second embodiment has the same configuration as the lid 10A of the first embodiment, except for the shape of the top cover portion 20B. Therefore, elements common to both lid 10A and the first embodiment are indicated by the same reference numerals, and their descriptions are omitted. In the lid 10B of the second embodiment, the top dome portion 20B is molded in a polyhedral (polygon) dome shape that bulges upward from the peripheral portion 30, as shown in Figure 6.

[0067] Here, a polyhedral dome shape refers to a dome shape formed by a polyhedron with multiple facets 50 combined to create a curved surface. Specifically, the canopy portion 20B of this embodiment is molded as a polyhedral dome shape, combining multiple facets 50 that form regular pentagons and multiple facets 50 that form regular hexagons. In this embodiment, it is preferable that the same parameters as those for the lid 10A are applied to the thickness, density, and curvature of the canopy portion 20B.

[0068] According to the lid 10B of the second embodiment, since the canopy portion 200 is molded in a polyhedral dome shape, the external force applied to the canopy portion 20B is easily dispersed, and thus strength can be ensured. In addition, elements common to lid 10A have the same effects as lid 10A. Although the canopy portion 20B shown in Figure 6 does not have a predetermined pattern formed on it, the same pattern 40 as on the canopy portion 20A may also be formed on the canopy portion 20B.

[0069] [D. Others] The embodiments described above are merely illustrative examples, and there is no intention to exclude various modifications or applications of techniques not explicitly stated in these embodiments. Each configuration of these embodiments can be modified in various ways without departing from their spirit. Furthermore, they can be selected and combined as needed. For example, as shown in Figure 7, the canopy portion 20C, which is molded into a hemispherical dome shape by the lid 10C, does not necessarily have a pattern 40 formed on it.

[0070] Furthermore, while Figure 1 illustrates a structure in which a notch 26, which functions as a straw insertion opening, is provided in the central part of the top portion 24 of the canopy portion 20A, the location of the notch that functions as a straw insertion opening is not limited to this. For example, as shown in Figure 8, in the lid portion 10D, a notch 28 that functions as a straw insertion opening may be provided in the side wall portion 22 of the canopy portion 20D.

[0071] The dome-shaped roof structure is not limited to a polyhedral dome formed by combining multiple pentagonal and hexagonal faces as shown in Figure 6, but may also be composed of polyhedra of any other shape. Specifically, a polyhedral dome formed by combining multiple equilateral triangles can be given as an example.

[0072] Figures 1 to 8 illustrate examples of canopy sections 20A and 20B in which the entire canopy section is formed into a dome shape, but it is also possible for only a part of the canopy section to be dome-shaped. For example, the canopy portion 20A in Figure 1 may have a hemispherical dome shape, with curved side walls and a flat top. In this case as well, the curved side walls ensure the strength of the lid. The curvature of the curved surface of the top portion 24 and the curved surface of the side wall portion 22 may be the same.

[0073] Furthermore, preferred pulp compositions for use in the lid of this embodiment are described below. First, we will discuss the elastic moduli of pulp sheets P1 to P6, which are made from different pulp raw materials. The pulp slurry used in pulp sheets P1 to P6 consists of the following pulp raw materials. <Pulp raw materials> P1: Espartot Grass P2: Bamboo P3: Bagasse (Bagasse Pulp) ·P4: Hemp • P5:L (Hardwood pulp, LBKP) P6:N (Coniferous pulp, NBKP)

[0074] In addition, pulp sheets P1 to P6 have the following specifications. (Pulp slurry) Freeness: 450 ml (Pulp slurry) concentration: 0.3 [mass%] Density (of the pulp sheet): 0.5 [g / cm³] 3 ] Basis weight (of pulp sheet): 60 g / m² 2 ] The elastic moduli of the pulp sheets P1 to P6 described above were measured according to Table 1 below. The elastic moduli were measured in accordance with JIS P 8113:2006.

[0075] [Table 1]

[0076] Table 1 shows that among non-wood pulps, bagasse had a higher modulus of elasticity than bamboo, hemp, and esvaldo grass, and among wood pulps, coniferous pulp had a higher modulus of elasticity than hardwood pulp. Bagasse pulp had a modulus of elasticity at almost the same level as coniferous pulp.

[0077] Next, we will discuss the ease with which the top of the lid returns to its original shape after being indented (deformed). Eleven types of lids, F1 to F11, were prepared, each molded using a pulp slurry with a different pulp composition ratio, as described below. <Pulp content ratio> F1: Hardwood pulp (LBKP) = 100% F2: Coniferous pulp (NBKP) = 100% F3: Bagasse pulp = 100% F4: Bamboo pulp = 100% F5: Recycled paper pulp = 100%

[0078] F6: LBKP / NBKP = 85% / 15% F7: LBKP / NBKP = 70% / 30% F8: LBKP / NBKP = 30% / 70% F9: LBKP / NBKP = 10% / 90% F10: LBKP / Bagasse = 70% / 30% F11: LBKP / Bagasse = 10% / 90% The pulp slurry used in each of the lids F1 to F11 had a freeness of 450 [ml] and a concentration of 0.3 [mass%].

[0079] Each of the lids F1 to F11 was prepared using the pulp slurry with the above-mentioned mixing ratios, following the steps 1 to 4 below. Step 1: Submerge the papermaking die, with a metal mesh attached to its surface, into the pulp slurry, inside the die Vacuum suction is performed from there. Step 2: The pulp slurry is applied to the metal mesh using the method from Step 1, creating a three-dimensional wet paper. It forms.

[0080] Step 3: The wet paper formed in Step 2 is transferred to a dewatering mold and subjected to a pressure of 0.65 MPa. Dehydrate by pressure. Step 4: Transfer the damp paper that has been pressure-dehydrated in Step 3 to a mold heated to 180°C, and 1.1 It was pressurized and dried at a pressure of MPa, resulting in a density of 0.6 g / cm³. 3 , lid with a thickness of 0.5 mm To create.

[0081] The lid produced in step 4 has a top section molded into a hemispherical dome shape without any patterns, as shown in lid 10C in Figure 7, and does not have a notch at the top (reference numeral 26 in Figure 7). The "returnability" of lids F1 to F11, which were produced in steps 1 to 4 described above, was evaluated. Returnability is an evaluation of how easily the indented part of the lid returns to its original state after being pressed in with a finger and then released. The returnability was evaluated by visually observing how the indentation returned to its original state.

[0082] Resilience was evaluated using the following five-point scale. "Five" is the best rating, and the rating decreases in order from "Four" downwards, with "One" being the lowest rating. 5: The dent went back to normal quickly. 4: After a short while, the dent returned to normal. Three: The dent returned to its original shape in a longer time than in "four". 2: The dent returned to its original shape slightly, but not completely. 1: The dent did not go away.

[0083] Of the lids F1 to F11, lids F2, F3, F9, and F11 received the best rating ("Five"). Lids F7, F8, and F10 received the next best rating ("Four") after lids F2, F3, F9, and F11. Lid F6 received a rating ("Three") which was inferior to lids F7, F8, and F10, but better than lids F1 and F4. Lids F1 and F4 received a rating ("Two") which was inferior to lid F6. Lid F5 received the worst rating ("One").

[0084] Based on the above considerations, it can be said that the pulp used for the lid in this embodiment preferably contains at least one of bagasse pulp and softwood pulp. This makes it possible to obtain a lid that is resistant to deformation even under external force (i.e., has a high modulus of elasticity). From the viewpoint of ensuring resilience, the content of at least one of bagasse pulp and softwood pulp relative to the total amount of pulp (or the total content if both bagasse pulp and softwood pulp are included) is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 75% by mass or more, and even more preferably 85% by mass or more. The upper limit of the content is 100% by mass. This makes it possible to obtain a lid that can easily return to its original shape even if it is temporarily dented (deformed) by external force. [Explanation of Symbols]

[0085] 5. Paper cups (containers) 5A open end 10A,10B,10C,10D Lid body 20A, 20B, 20C, 20D Canopy section 22 Side wall section 24 Top 26, 28 Cut section 30 Peripheral area 32 Engagement groove 32A Exterior wall 32B Inner wall 32C connector 40 patterns 50 sides

Claims

1. A lid made of pulp mold, primarily composed of pulp, comprising a top portion that covers the opening of a bottomed cylindrical container, and a peripheral portion provided on the periphery of the top portion and attached to the opening end of the container, The aforementioned lid portion, when attached to the container, bulges out in a direction away from the container and is molded into a hemispherical dome shape that forms a continuous curved surface. The pulp contains at least one of bagasse pulp and softwood pulp. The content of at least one of the bagasse pulp and the coniferous pulp relative to the total amount of the pulp is 30% by mass or more. A lid characterized by the following features.

2. The canopy portion has a side wall portion erected from the inner circumference of the peripheral edge portion, and a top portion connected to the side wall portion and forming a part that covers the opening when attached to the container, The side wall portion and the top portion are integrally molded into a dome shape. The lid according to feature 1.

3. The radius of curvature ratio, defined by the ratio of the radius of the circle along the arc appearing in the cross-section along the vertical direction of the canopy portion to the inner diameter of the open end, is 0.32 or greater and 0.56 or less. The lid according to feature 1 or 2.

4. The thickness dimension of the canopy portion is 0.3 mm or more and 2.0 mm or less. A lid according to any one of the features 1 to 3.

Images