Spouting member, manufacturing method of spouting member, and molding die used in the manufacturing method of spouting member

Abstract

To provide a spouting member with improved openability when one of the inner and outer portions is cut off from the other and opened.SOLUTION: A cap member 1 includes an inner portion 2, an outer portion 3 located outside of the inner portion 2, and a connecting portion 4. The connecting portion 4 connects the inner portion 2 and the outer portion 3 and includes a region to be cut out when one of the inner portion 2 and the outer portion 3 is cut out from the other. A plurality of independent bubbles 7 is formed in the interior of the connecting portion 4.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a pouring member, a method for manufacturing a pouring member, and a molding die used in the method for manufacturing a pouring member. [Background technology]

[0002] Patent Document 1 discloses a plug that includes a closing plate located on the inside, a dispensing tube located on the outside, and a circumferential thin-walled portion that connects the closing plate and the dispensing tube. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-189641 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional spouts, such as stoppers, the connecting portion connecting the inner portion (e.g., a sealing plate) and the outer portion (e.g., a spout tube) is thin-walled because it is the area that is cut off when opening the inner portion. From the perspective of improving ease of opening, it is desirable for the connecting portion to be as thin as possible. On the other hand, from the perspective of moldability when molding the spout, making the connecting portion too thin (e.g., less than 0.2 mm) can result in short shots and other problems, reducing the fluidity of the molten resin downstream of the connecting portion, resulting in molding defects. Therefore, it is preferable for the connecting portion to have a certain thickness. Furthermore, if the connecting portion is too thin, pinholes can form, causing leakage in the cap member or causing it to break during transportation. Therefore, it is desirable to improve the openability of spouts while ensuring the thickness of the connecting portion.

[0005] The present invention aims to provide a pouring member, a method for manufacturing a pouring member, and a molding die used in the method for manufacturing a pouring member, which can improve the ease of opening when one of the inner and outer parts is cut off from the other to open the member. [Means for solving the problem]

[0006] One aspect of the present invention relates to a dispensing member. The dispensing member includes an inner portion, an outer portion located outside the inner portion, and a connecting portion connecting the inner portion and the outer portion and including a region to be cut when one of the inner portion and the outer portion is cut from the other. In this dispensing member, a plurality of closed cells are formed inside the connecting portion.

[0007] In this spouting member, multiple closed bubbles are formed inside the connecting portion that connects the inner and outer portions and includes a region to be cut off when one of the inner and outer portions is torn off from the other. This ensures the thickness of the connecting portion connecting the inner and outer portions, while providing multiple closed bubbles reduces the force required to cut off the connecting portion, improving the ease of opening when cutting off one of the inner and outer portions from the other. Furthermore, providing multiple closed bubbles within the connecting portion also reduces the weight of the spouting member. Furthermore, since the connecting portion is thick, this spouting member can reduce molding defects and prevent pinholes and breakage during transportation.

[0008] In the dispensing member, each of the plurality of closed cells has a length of 10 μm or more and 400 μm or less, when the longest side passing through the center of gravity of the cell is taken as the cell length, and the number of the plurality of closed cells per unit volume is 0.3 cells / mm 3 More than 8.5 pieces / mm 3It is preferable that the number of bubbles per unit area is 0.1 or less. In this case, the force required to cut off the connecting portion can be more efficiently reduced while ensuring the thickness of the connecting portion, thereby improving the ease of opening. Furthermore, if the thickness of the connecting portion where the closed bubbles are formed is sufficiently thin (for example, about 0.5 mm or less) and light can be transmitted through it, the number of bubbles per unit area can be specified. In this case, the number of bubbles per unit area of ​​a plurality of closed bubbles having a bubble length of 10 μm or more and 400 μm or less is 0.1 bubbles / mm 2 More than 2.5 pieces / mm 2 On the other hand, when the film is made of a material that does not transmit light, the region including the connecting portion may be cut and the number of bubbles per unit area present on the cut surface may be counted. In this case, the number of bubbles per unit area of ​​a plurality of closed bubbles having a bubble length of 10 μm or more and 400 μm or less is 0.1 bubbles / mm or less, as in the above. 2 More than 2.5 pieces / mm 2 The number of bubbles may be less than or equal to the number of bubbles in the specimen. The number of bubbles may be calculated by measuring with an optical microscope, or may be calculated directly from the obtained image, or may be calculated by subjecting the obtained image to predetermined image processing such as binarization. When observing with an optical microscope, it is preferable to obtain a cross-sectional image along the thickness direction of the connecting portion, but a cross-sectional image perpendicular to the thickness direction of the connecting portion may also be obtained. When observing with an optical microscope, it is preferable to cut the connecting portion thin enough to be observable.

[0009] In the above-mentioned spouting member, the thickness of the connecting portion is preferably 0.2 mm to 0.4 mm. Having a connecting portion thickness of 0.2 mm or more more reliably prevents molding defects such as short shots from occurring when molding the spouting member, making it possible to produce a spouting member with excellent dimensional accuracy. Furthermore, pinholes are prevented from forming in the connecting portion, preventing leakage from the spouting member. Furthermore, breakage of the connecting portion during transportation is more reliably prevented. On the other hand, having a connecting portion thickness of 0.4 mm or less prevents the force required to cut the connecting portion from being too high, which, in combination with the presence of multiple closed bubbles, further improves the ease of opening. Note that the "thickness of the connecting portion" herein refers to the thickness of the thinnest portion of the connecting portion.

[0010] In the above-described pouring member, the outer portion has a flange portion for attaching the pouring member to a container body, and a plurality of closed cells may be formed inside the flange portion. In this case, the closed cells formed inside the flange portion can suppress the occurrence of sink marks that tend to occur during molding in the flange portion and its surrounding area, which have a mixture of thin and thick portions. This allows the pouring member to be a molded product with high dimensional accuracy. Furthermore, with this pouring member, the high dimensional accuracy of the flange portion can improve heat sealing properties when attached to other members such as a container body.

[0011] Another aspect of the present invention relates to a method for manufacturing a pouring member having an inner portion, an outer portion, and a connecting portion connecting the inner portion and the outer portion by supercritical fluid molding. This method for manufacturing a pouring member includes the steps of (A) preparing a molten resin composition containing a resin material and a supercritical fluid, (B) injecting the molten resin composition into a cavity of a mold corresponding to the pouring member, (C) holding the molten resin composition injected into the cavity under pressure, and (D) core-backing a first movable portion of the mold corresponding to the connecting portion.

[0012] In this method for manufacturing a pouring member, the first movable mold is cored back in the area corresponding to the connecting portion to partially release the pressure of the molten resin composition and create a finely foamed supercritical fluid in the molten resin composition. This facilitates the formation of multiple closed bubbles within the connecting portion, which is one of the specific locations of the pouring member. In other words, this manufacturing method allows closed bubbles to be formed not throughout the entire pouring member, but only at the desired location (the connecting portion in this example). This facilitates the manufacture of a pouring member having a connecting portion with a predetermined thickness that improves the ease of opening by cutting one of the inner and outer portions from the other. Furthermore, because this manufacturing method uses supercritical fluid molding, the inner and outer portions of the pouring member can be formed thin while maintaining their strength, thereby reducing the amount of plastic resin material used.

[0013] In the above-described method for manufacturing a pouring member, the outer portion may have a flange portion for attaching the pouring member to a container body. In the injecting step (B), the molten resin composition may be injected into the mold cavity through a gate located in a region corresponding to the inner portion. This method for manufacturing a pouring member may further include a step (E) of core-backing a second movable mold corresponding to the flange portion of the mold. In this case, core-backing the second movable mold facilitates the formation of multiple closed cells within the flange portion, thereby suppressing the occurrence of sink marks that tend to occur during molding of a flange portion having a mixture of thin and thick portions. Therefore, this manufacturing method can produce a pouring member with a flange portion having high dimensional accuracy. Furthermore, this manufacturing method for a pouring member can improve the dimensional accuracy of the flange portion, thereby also improving the heat-sealability when attaching the pouring member to another member, such as a container body.

[0014] In the above-mentioned manufacturing method of a dispensing member, in at least one of the core-backing steps (D) and (E), it is preferable to core back a distance that is 25% to 35% of the final thickness of the corresponding parts of the connecting portion and flange portion after core-backing. In this case, it becomes possible to easily form multiple closed cells with the desired porosity in the connecting portion, flange portion, etc. Note that the "final thickness" here refers to the thickness of the connecting portion or flange portion when the dispensing member is manufactured by the above-mentioned manufacturing method.

[0015] In yet another aspect, the present invention relates to a mold used in a manufacturing method for a spouting member. This mold is a mold used in any of the manufacturing methods for a spouting member described above, and includes a fixed mold and a movable mold that can be moved relative to the fixed mold when core-backing and corresponds to the connecting portion. In this case, when molding a spouting member using a mold with the above configuration, it is possible to easily provide multiple closed cells with a desired porosity in the connecting portion. [Effects of the Invention]

[0016] According to the present invention, it is possible to improve the ease of opening when one of the inner portion and the outer portion is cut off from the other portion to open the package. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a cross-sectional view showing an example of a cap member according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view of the vicinity S of the connecting portion of the cap member shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view showing a part (lower die) of a molding die for producing the cap member shown in FIG. 1 by supercritical fluid molding, and the molded cap member. [Figure 4]Figure 4 is a cross-sectional view illustrating a method of performing core backing to generate closed cells in the connecting portion when molding the cap member shown in Figure 1 using supercritical fluid molding, where (a) shows the state of the connecting portion before core backing, and (b) shows the state of the connecting portion after core backing. [Figure 5] FIG. 5 is a diagram illustrating the thickness of the connecting portion in a conventional cap member. DETAILED DESCRIPTION OF THE INVENTION

[0018] A cap member, a method for manufacturing the cap member, and a molding die used in the method for manufacturing the cap member according to one embodiment of the present invention will be described in detail below with reference to the drawings. In the description, the same elements or elements having the same functions may be designated by the same reference numerals, and redundant description will be omitted. Note that the present invention is not limited to the following embodiment.

[0019] FIG. 1 is a cross-sectional view showing a cap member according to one embodiment of the present invention, and more specifically, a cross-sectional view showing a spout with a pull ring. The cap member 1 is, for example, a spout with a pull ring or a cap with a pull ring, and is a pouring member attached to the opening of a container body (not shown) that contains a predetermined content (e.g., a seasoning). The cap member 1 may be either a stopper type or a screw type, and the content stored in the container body to which the cap member 1 is attached may be any of food, non-food, powder, and liquid. The cap member 1 may be configured with or without a lid.

[0020] As shown in FIG. 1 , the cap member 1 includes an inner portion 2, an outer portion 3, and a connecting portion 4. In the cap member 1, the outer portion 3 is attached to the opening of the container body by heat sealing, and the inner portion 2 functions as a lid that closes the container body to prevent contents stored in the container body from leaking out during transportation or carrying. When using contents stored in the container body, the inner portion 2 is cut off from the outer portion 3 using the connecting portion 4 as a cutting area. This makes it possible to remove the contents from the inner region of the cap member 1 where the inner portion 2 was located. Such a cap member 1 can be manufactured as a single unit by resin molding, as described below.

[0021] The inner part 2 is a generally cylindrical part with a bottom that is disposed inside the outer part 3, and is connected to the outer part 3 via a connecting part 4 located on the outside. The inner part 2 is not connected to the outer part 3 at any point other than the connecting part 4. The inner part 2 is, for example, a member such as a pull ring, and functions to close the opening of the container body when the cap member 1 is attached to a container and used for transportation, etc. On the other hand, the inner part 2 is configured to be cut off from the outer part 3 by the connecting part 4 when the contents contained in the container body are used. By cutting off the inner part 2 from the outer part 3, the opening of the container body to which the cap member 1 is attached is opened. Note that the inner part 2 may be configured to fit into a portion extending from the top surface of a lid member (not shown) attached to the cap member 1, so that the inner part 2 can be cut off from the outer part 3 at the same time as removing the lid member without the user having to pull it directly by hand (so-called one-touch opening).

[0022] The outer portion 3 is a generally cylindrical portion located outside the inner portion 2 and serves as a base when attaching the cap member 1 to the container body. The outer portion 3 has a flange portion 5 for attaching the cap member 1 to the container body. The outer portion 3 is integrally connected to the inner portion 2 by a connecting portion 4 provided on the inner circumferential surface. The outer portion 3 is connected to the inner portion 2 only by the connecting portion 4, and is not connected in any other portion. The outer portion 3 may have a thread portion 6 on its outer circumferential surface for attaching a cap or the like (not shown) to the cap member 1. The outer portion 3 may also have a protrusion or a claw portion that fits into the opening of the container body instead of the flange portion 5 as a structure for attaching it to the container body.

[0023] The connecting portion 4 connects the inner portion 2 and the outer portion 3 and is a region to be cut off when the inner portion 2 is to be cut off from the outer portion 3. The connecting portion 4 is a thin-walled portion that extends circumferentially between the inner portion 2 and the outer portion 3, and has a thickness T of 0.2 mm to 0.4 mm, for example, 0.3 mm (see FIG. 2). By making the thickness T of the connecting portion 4 0.3 mm, it is possible to prevent the connecting portion 4 from breaking during transportation of the container body to which the cap member 1 is attached. Note that the thickness T of the connecting portion 4 refers to the thickness of the thinnest portion of the connecting portion 4.

[0024] Furthermore, as shown in FIG. 2, a plurality of closed cells 7 are formed inside the connecting portion 4. Closed cells 7 refer to cells that exist independently of each other, and include cells that are in contact with adjacent cells as long as they are not connected to each other. Such closed cells 7 can be formed by supercritical fluid molding, which will be described later. By providing voids inside the connecting portion 4, the cap member 1 maintains a certain thickness (wall thickness T) while reducing the force required to cut off the connecting portion 4. Note that such closed cells are not formed in the inner portion 2 or the outer portion 3, and are configured so that parts other than the connecting portion 4 do not become the starting point for cutting.

[0025] More specifically, each of the closed cells 7 formed in the connecting portion 4 may have a cell length of 10 μm to 400 μm, or 10 μm to 300 μm, or 200 μm to 300 μm, where the cell length is the longest side passing through the center of gravity of the cell. The number of cells per unit volume of the multiple closed cells 7 in the connecting portion 4 is, for example, 0.3 cells / mm 3 More than 8.5 pieces / mm 3 Furthermore, if the thickness of the connecting portion 4 where the closed bubbles 7 are formed is sufficiently thin (for example, about 0.5 mm) to allow light to pass through, the number of bubbles per unit area can be specified. In this case, the number of bubbles per unit area of ​​the multiple closed bubbles 7 in the connecting portion 4 is 0.1 bubbles / mm 2 More than 2.5 pieces / mm 2 It may be the following:

[0026] On the other hand, when the cap member 1 is made of a material that does not transmit light, the region including the connecting portion 4 may be cut and the number of bubbles present per unit area on the cut surface may be counted. In this case, the number of bubbles per unit area of ​​the multiple closed bubbles 7 in the connecting portion 4 is 0.1 bubbles / mm , as described above. 2 More than 2.5 pieces / mm 2 The number of bubbles may be calculated directly from an image captured with a microscope at a magnification of 35 times, for example, or may be calculated by performing predetermined image processing on the obtained image. Note that "no independent bubbles are formed in the inner portion 2 or the outer portion 3" means that there are no independent bubbles visible to the naked eye, or the number of bubbles per unit area visible at a microscope at a magnification of 35 times is 0.01 bubbles / mm 2This means that the number of bubbles is equal to or less than 200 μm. Generally, the lower limit of the bubble length of bubbles that can be visually confirmed is 200 μm, so "there are no independent bubbles that can be visually confirmed" means that there are no bubbles with a bubble length exceeding 200 μm. Furthermore, in terms of determining whether or not independent bubbles are formed, the bubble length of bubbles that can be confirmed when the magnification of the microscope is set to 35 times may exceed 200 μm. In other words, even if bubbles exceeding 200 μm are confirmed when observed under a microscope, the number of bubbles per unit area may be less than 0.01 bubbles / mm. 2 If the value is less than this, it is determined that no closed cells have been formed.

[0027] In the cap member 1, the presence of such multiple closed bubbles 7 within the connecting portion 4 maintains the thickness T of the connecting portion 4 at a predetermined thickness (e.g., 0.3 mm) while reducing the force required for tearing, improving the ease of opening when tearing the inner portion 2 from the outer portion 3. Also, the provision of voids within the connecting portion 4 reduces the amount of plastic material used in the cap member 1, thereby achieving weight reduction. Furthermore, a skin layer is formed on the surface of the connecting portion 4, preventing the closed bubbles 7 from appearing on the surface, maintaining an aesthetic appearance.

[0028] Next, a method for manufacturing the cap member 1 will be described with reference to Figures 3 to 5. Figure 3 is a cross-sectional view showing a part of a molding die (lower die) for manufacturing the cap member shown in Figure 1 by supercritical fluid molding, and the molded cap member 1. Figure 4 is a cross-sectional view for explaining a method for generating closed cells 7 in the connecting portion 4 by performing core backing when molding the cap member 1 by supercritical fluid molding, where (a) shows the state of the connecting portion before performing core backing, and (b) shows the state of the connecting portion 4 after performing core backing. Figure 5 is a view for explaining the thickness of the connecting portion in a conventional cap member.

[0029] The cap member 1 is manufactured through the following steps. (A) A step of preparing a molten resin composition containing a resin material and a supercritical fluid. (B) A step of injecting a molten resin composition into a cavity of a mold. (C) After the above step (B), a step of holding the cavity under pressure and cooling it. (D) A step of core-backing the movable mold corresponding to the connecting portion of the mold during the above step (C). (E) Removing the container from the mold. The series of steps (A) to (E) can be carried out, for example, using a MuCell injection molding machine ("MuCell" is a registered trademark of Trexel Co. Ltd.) (see, for example, Japanese Patent Nos. 6085729 and 6430684).

[0030] [(A) Process] First, a molten resin composition containing a resin material and a supercritical fluid is prepared. Examples of the resin material include thermoplastic resins, such as polypropylene resin and polyethylene resin. The melt flow rate of the thermoplastic resin is preferably 15 g / 10 min or more, more preferably 20 to 40 g / 10 min, and even more preferably 25 to 36 g / 10 min. A melt flow rate of 15 g / 10 min or more tends to suppress the occurrence of short shots, while a melt flow rate of 40 g / 10 min or less tends to produce containers with excellent drop resistance. The melt flow rate (MFR) is a value measured in accordance with the method described in JIS K7210-1:2014 under conditions of a temperature of 230°C and a load of 2.16 kg. Short shots refer to a phenomenon in which the resin material does not reach the flow end of the cavity.

[0031] To mold a component with a thin wall using conventional injection molding, it was necessary to select a resin with high fluidity (high MFR value) to prevent short shots. However, resin materials with high fluidity tend to have a relatively low molecular weight and low strength, making it difficult to manufacture thin-walled containers with excellent drop resistance. In contrast, in this embodiment, even if a resin material has a relatively low MFR value, the fluidity of the molten resin composition can be increased by using it in combination with a supercritical fluid. This makes it possible to achieve both short shot prevention and excellent strength (e.g., buckling strength and drop resistance).

[0032] When carbon dioxide is used as the supercritical fluid, 1 to 4 parts by mass, preferably 2 to 3 parts by mass, of supercritical carbon dioxide is added to 100 parts by mass of the resin material to prepare the molten resin composition. Using 2 parts by mass or more of carbon dioxide reduces the variation in filling pressure between molding shots, and the addition of carbon dioxide reduces the viscosity of the molten resin composition, thereby suppressing the occurrence of short shots. Additionally, foaming caused by supercritical carbon dioxide can be promoted, for example, at the flow end (e.g., the flange portion 5 of the outer portion 3), to form voids within a portion of the molded body. On the other hand, using 3 parts by mass or less of carbon dioxide can impair foaming, resulting in an inability to form a uniform bubble layer, resulting in unevenness, or insufficient weight reduction.

[0033] When nitrogen is used as the supercritical fluid, 0.5 to 1.5 parts by mass of supercritical nitrogen is added to 100 parts by mass of resin material to prepare the molten resin composition. By adding 0.5 parts by mass or more of nitrogen, it is possible to reduce the variation in filling pressure between molding shots, and the addition of nitrogen reduces the viscosity of the molten resin composition, thereby suppressing the occurrence of short shots. In addition, the promotion of foaming due to supercritical nitrogen can form voids within the molded product. On the other hand, if the amount of nitrogen is 1.5 parts by mass or less, foaming properties are impaired, resulting in an inability to form a uniform bubble layer, resulting in unevenness, or insufficient weight reduction.

[0034] The temperature of the molten resin composition (screw cylinder temperature) may be set according to the melting point or MFR of the resin material. When polypropylene resin is used, this temperature is preferably about 210 to 250°C. When polyethylene resin is used, this temperature is preferably about 220 to 260°C. When this temperature is equal to or higher than the lower limit, the resin flows easily in the cavity, while when it is equal to or lower than the upper limit, burning of the resin tends to be suppressed.

[0035] The molten resin composition may contain components other than the resin material and the supercritical fluid, i.e., the molten resin composition may further contain, as necessary, for example, a filler, a colorant, a slip agent, an antistatic agent, etc.

[0036] [(B) Process] The molten resin composition prepared in step (A) is injected into the cavity through gate G of the molding die M corresponding to the cap member 1. At this time, as shown in FIG. 3, injection molding is performed with the side corresponding to the inner portion 2 designated as gate G and the side corresponding to the flange portion 5 of the outer portion 3 designated as the flow terminal. The molding die M includes a fixed die M1 corresponding to the inner portion 2, a movable die M2 (first movable die) corresponding to the connecting portion 4, and a fixed die M3 corresponding to the outer portion 3. The movable die M2 is configured to be movable (retractable) in the direction of arrow A relative to the fixed dies M1 and M3. Note that the upper molding die is not shown in FIG. 3. When the molten resin composition is introduced into the cavity of the molding die M via the above-described flow path, the gate G side is likely to maintain a predetermined pressure. On the other hand, a pressure drop is likely to occur at the flange portion 5, which is the flow terminal, as will be explained in step (C) below.

[0037] The injection speed of the molten resin composition in step (B) is preferably 100 to 400 mm / sec, more preferably 150 to 200 mm / sec. An injection speed of 100 mm / sec or higher tends to allow the resin to reach the end of the flow, thereby suppressing the occurrence of short shots. On the other hand, an injection speed of 400 mm / sec or lower tends to suppress the occurrence of flash defects in the molded article. In the method for producing a cap member according to this embodiment, the injection speed may be set in multiple stages, with the initial injection speed being 250 to 350 mm / sec and the second stage speed being reduced to 50 to 150 mm / sec. By reducing the injection speed in this manner, it is possible to improve the transferability of the mold and prevent solidification during molding.

[0038] [(C) Process] In step (C), after step (B), the cavity is cooled while being dwelled. The dwell pressure applied after injection may be 20 to 50 MPa, for example, 30 MPa. The dwell time is 0.5 to 1.5 seconds, for example, 1.0 second. This dwell pressure prevents supercritical fluids such as carbon dioxide and nitrogen from foaming in the inner portion 2, connecting portion 4, and outer portion 3 (excluding flange portion 5) near the gate. Meanwhile, in the flange portion 5, which is located at the end of the flow away from the gate, the dwell pressure is likely to decrease, which may cause foaming of supercritical fluids such as carbon dioxide and nitrogen. This prevents bubbles from forming in the inner portion 2 and outer portion 3 (excluding flange portion 5). The amount and size of bubbles generated in the flange portion 5 can be adjusted by adjusting the dwell pressure and the length of the dwell time.

[0039] [(D) Process] In step (D), while the pressure is being held in step (C), the movable mold M2 of the molding mold M is cored back in the direction of arrow A in FIGS. 3 and 4(a). This expands the portion 4A corresponding to the connecting portion 4, and multiple closed cells 7 are formed therein, as shown in FIG. 4(b). Meanwhile, since the fixed mold M1 located in the center of the molding mold M is not moved during core-back, multiple closed cells are not formed in the portion corresponding to the inner portion 2. Furthermore, since the fixed mold M3 located on the outer side of the molding mold M is not moved during core-back, multiple closed cells are not formed in the portion corresponding to the outer portion 3, except in the region corresponding to the flange portion 5. However, the portion of the fixed mold M3 corresponding to the flange portion 5 may be divided into a movable mold (second movable mold), and core-back may be performed in the region corresponding to the flange portion 5, similar to the connecting portion 4. In this case, multiple closed cells can be more reliably formed in the flange portion 5.

[0040] Here, the amount of core-back in step (D) will be explained. FIG. 5 shows a conventional cap member 11. As shown in FIG. 5, in the conventional cap member 11, the inner portion 12 and the inner portion 13 are connected by a connecting portion 14 having a predetermined thickness T. This thickness T is set to a thickness that will prevent the connecting portion 14 from breaking during transportation. In this embodiment, the connecting portion 4 is expanded by the core-back, so as shown in FIG. 4(a), the thickness t of the connecting portion 4A immediately after injection is thinner than the predetermined thickness T. Subsequently, by core-backing, the connecting portion 4A is expanded into the connecting portion 4, resulting in the thickness T. This results in a thickness that is sufficient to prevent breakage during transportation. The amount of core-back may be appropriately set depending on the shape and number of closed cells 7 formed in the connecting portion 4. For example, it may be 25% to 35% of the thickness T (final thickness) of the connecting portion 4 of the cap member 1 to be manufactured. As an example, when the thickness of the connecting portion 4 is 0.2 mm to 0.3 mm, the amount of core-back may be 0.1 mm or less. A skin layer may be formed on the surface of the core-backed connecting portion.

[0041] [(E) Process] In step (E), after steps (C) and (D) above, the molded body (cap member 1) is recovered from the molding die M when the temperature of the molded body in the die has dropped to about 30 to 60°C. This allows the desired cap member 1 to be obtained. In this embodiment, pressure is maintained in step (C), so large voids that are visible to the naked eye are not formed in the cap member 1. However, if bubbles formed in the connecting portion 4 or flange portion 5 of the cap member 1 deteriorate the appearance, this can be addressed by adding a colorant to the molten resin composition used for molding.

[0042] As described above, in the cap member 1 according to this embodiment, a plurality of closed bubbles 7 are formed inside the connecting portion 4. This ensures that the thickness T of the connecting portion 4 connecting the inner portion 2 and the outer portion 3 is a desired thickness, while the provision of a plurality of closed bubbles 7 reduces the force required to cut off the connecting portion 4, thereby improving the ease of opening when cutting the inner portion 2 from the outer portion 3 to open the package. In addition, the provision of a plurality of closed bubbles 7 inside the connecting portion 4 also contributes to reducing the weight of the cap member 1. Furthermore, since the thickness T of the connecting portion 4 can be set to a desired thickness in the cap member 1, molding defects can be reduced and the occurrence of pinholes and breakage during transportation can be prevented.

[0043] In this embodiment, each of the plurality of closed cells 7 has a length of 10 μm or more and 400 μm or less, where the length is the longest side passing through the center of gravity of the cell, and the number of cells per unit volume of the plurality of closed cells 7 is 0.3 cells / mm 3 More than 8.5 pieces / mm 3 In this case, the force required to cut off the connecting portion 4 can be more efficiently reduced while the thickness T of the connecting portion 4 is set to a desired thickness, thereby improving the ease of opening.

[0044] In this embodiment, the thickness T of the connecting portion 4 is preferably 0.2 mm to 0.4 mm. Having a thickness of 0.2 mm or more for the connecting portion 4 more reliably prevents molding defects such as short shots from occurring during molding of the cap member 1, making it possible to produce a cap member 1 with excellent dimensional accuracy. Furthermore, pinholes are prevented from being formed in the connecting portion 4, thereby preventing leakage from the cap member 1. Furthermore, breakage of the connecting portion 4 during transportation is more reliably prevented. On the other hand, having a thickness of 0.4 mm or less for the connecting portion 4 prevents the force required to cut the connecting portion 4 from being too high, which, in combination with the presence of the multiple closed bubbles 7, further improves the ease of opening.

[0045] In this embodiment, the outer portion 3 has a flange portion 5 for attaching the cap member 1 to the container body, and a plurality of closed cells may be formed inside the flange portion 5. In this case, the closed cells formed inside the flange portion 5 can suppress the occurrence of sink marks that tend to occur during molding in the flange portion 5 and its surrounding area, which have a mixture of thin and thick portions. This allows the cap member 1 to be a molded product with high dimensional accuracy. Furthermore, the high dimensional accuracy of the flange portion 5 of the cap member 1 allows for improved heat sealing properties when attached to another member, such as a container body.

[0046] Furthermore, in the cap member manufacturing method according to this embodiment, the movable mold M2 is cored back in the region corresponding to the connecting portion 4 to partially release the pressure of the molten resin composition and cause the supercritical fluid in the molten resin composition to become finely foamed. This facilitates the formation of multiple closed cells 7 within the connecting portion 4, which is one of the specific locations of the cap member 1. In other words, this manufacturing method allows the closed cells 7 to be formed not throughout the entire cap member 1 but only at the desired location (the connecting portion 4 in this example). This facilitates the manufacture of a cap member 1 having a connecting portion 4 with a predetermined thickness T that improves the ease of opening the cap member 1 by cutting the outer portion 3 from the inner portion 2. Furthermore, because the manufacturing method uses supercritical fluid molding, the inner portion 2 and outer portion 3 of the cap member 1 can be formed thin while maintaining their strength, thereby reducing the amount of plastic resin material used.

[0047] The method for manufacturing a cap member according to this embodiment may further include a step of core-backing a movable die of the molding die M that corresponds to the flange portion 5. In this case, core-backing the movable die facilitates the formation of multiple closed cells within the flange portion 5, thereby suppressing the occurrence of sink marks that tend to occur during molding of a flange portion that has a mixture of thin and thick portions. Therefore, this manufacturing method can produce a cap member 1 with a flange portion 5 that has high dimensional accuracy. Furthermore, this method for manufacturing a cap member can improve the dimensional accuracy of the flange portion 5, thereby also improving the heat-sealability when attaching the cap member to another member, such as a container body.

[0048] Furthermore, in the method for manufacturing a cap member according to this embodiment, in the step of core-backing the connecting portion 4 or the flange portion 5, it is preferable to core-back a distance that is 25% to 35% of the final thickness T of the corresponding portion of the connecting portion 4 and the flange portion 5 after core-backing. In this case, it becomes possible to easily form a plurality of closed cells 7 with a desired porosity in the connecting portion 4, the flange portion 5, etc.

[0049] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in the above embodiments, a cap member 1 configured such that the inner portion 2 is cut from the outer portion 3 has been described. However, the present invention is not limited to this, and the outer portion 3 may be cut from the inner portion 2 by a connecting portion 4. In other words, the present invention is applicable as long as one of the inner portion 2 and the outer portion 3 is cut from the other. Furthermore, in the above embodiments, examples have been given in which carbon dioxide or nitrogen is used as the supercritical fluid, but argon or helium, for example, may be used instead of these gases. [Explanation of symbols]

[0050] 1... Cap member, 2... Inner part, 3... Outer part, 4... Connection part, 5... Flange part, 7... Closed cell, M... Molding mold, M1, M3... Fixed mold, M2... Movable mold (first movable mold).

Claims

1. The inner part and an outer portion located outside the inner portion; A spouting member comprising: a connecting portion that connects the inner portion and the outer portion and includes a planned cutting area when cutting one of the inner portion and the outer portion from the other; A plurality of closed cells are formed inside the connecting portion, the outer portion has a flange portion for attaching the dispensing member to a container body, A spouting member, wherein a plurality of closed cells are formed inside the flange portion.

2. Each of the plurality of independent bubbles formed inside the connecting portion has a bubble length of 10 μm or more and 400 μm or less, when the bubble length is the longest side passing through the center of gravity of each bubble, The number of the closed cells formed inside the connecting portion per unit volume is 0.3 / mm ３ 8.5 pieces / mm or more ３ Below is the The dispensing member according to claim 1.

3. The thickness of the connecting portion is 0.2 mm to 0.4 mm. The spout member according to claim 1 or 2.

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