JP7806472B2 - Spouting member, manufacturing method of spouting member, and molding die used in the manufacturing method of spouting member - Google Patents

Description

The present invention relates to a dispensing member, a method for manufacturing a dispensing member, and a molding die used in the method for manufacturing a dispensing member.

Patent Document 1 discloses a stopper that includes an inner sealing plate, an outer dispensing tube, and a thin, peripheral portion that connects the sealing plate and the dispensing tube.

Japanese Patent Application Laid-Open No. 2020-189641

In conventional spouts and other dispensing components, the connecting portion connecting the inner portion (e.g., a closure plate) and the outer portion (e.g., a dispensing tube) is thin-walled because it is the area that is cut off when opening the inner portion. From the perspective of improving openability, 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 dispensing component, making the connecting portion too thin (e.g., less than 0.2 mm) can result in short shots and reduced fluidity of the molten resin in the portion downstream of the connecting portion, resulting in molding defects. Therefore, it is preferable for the connecting portion to have a certain degree of thickness. Furthermore, if the connecting portion is too thin, pinholes can form, causing leakage in the cap member or the cap member can break during transportation. Therefore, it is desirable to improve openability of dispensing components while ensuring the thickness of the connecting portion.

The present invention aims to provide a spouting member, a method for manufacturing a spouting member, and a molding die used in the method for manufacturing a spouting member that can improve the ease of opening when one of the inner and outer portions is cut away from the other.

One aspect of the present invention relates to a dispensing member. This dispensing member comprises an inner portion, an outer portion located outside the inner portion, and a connecting portion that connects the inner portion and the outer portion and includes a region to be cut when one of the inner portion and the outer portion is cut away from the other. In this dispensing member, multiple closed cells are formed inside the connecting portion.

In this dispensing member, multiple closed bubbles are formed inside the connecting portion, which connects the inner and outer portions and includes the area 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 one of the inner and outer portions from the other to open it. Furthermore, providing multiple closed bubbles within the connecting portion also reduces the weight of the dispensing member. Furthermore, since the connecting portion of this dispensing member maintains its thickness, it is possible to reduce molding defects and prevent pinholes and breakage during transportation.

In the above-described dispensing member, each of the plurality of closed cells preferably has a cell length of 10 μm to 400 μm, where the cell length is the longest side passing through the center of gravity of each cell, and the number of cells per unit volume of the plurality of closed cells is preferably 0.3 to ^8.5 cells/ ^mm³ . 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 openability. Furthermore, if the connecting portion where the closed cells are formed is sufficiently thin (e.g., about 0.5 mm or less) to allow light to pass through, the number of cells per unit area can also be specified. In this case, the number of cells per unit area of the plurality of closed cells having a cell length of 10 μm to 400 μm may be 0.1 to ^2.5 cells/ ^mm² . On the other hand, when the film is formed from a material that does not transmit light, the region including the connecting portion 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 multiple closed bubbles having a bubble length of 10 μm to 400 μm may be 0.1 bubbles/ ^mm2 to 2.5 bubbles/ ^mm2 , as described above. The number of bubbles may be calculated by measurement using an optical microscope, directly from the obtained image, or by subjecting the obtained image to predetermined image processing such as binarization. When observing using 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 using an optical microscope, it is preferable to cut the connecting portion thin enough to be observable.

In the above-mentioned dispensing 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 when molding the dispensing member, making it possible to produce a dispensing member with excellent dimensional accuracy. Furthermore, pinholes are prevented from forming in the connecting portion, preventing leakage from the dispensing 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 openability. Note that the "thickness of the connecting portion" referred to here refers to the thickness of the thinnest part of the connecting portion.

In the above-mentioned dispensing member, the outer portion has a flange portion for attaching the dispensing member to the container body, and multiple 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 are a mixture of thin and thick portions. This makes it possible to produce a dispensing member that is a molded product with high dimensional accuracy. Furthermore, with this dispensing member, the high dimensional accuracy of the flange portion improves heat sealing properties when attached to other members such as the container body.

In another aspect, the present invention relates to a method for manufacturing a pouring member by supercritical fluid molding, the pouring member having an inner portion, an outer portion, and a connecting portion connecting the inner portion and the outer portion. This pouring member manufacturing method 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.

In this method of manufacturing a pouring member, the first movable mold is cored back in the area corresponding to the connecting portion to partially release the pressure in the molten resin composition and create a finely foamed supercritical fluid in the molten resin composition. This facilitates the formation of multiple closed cells within the connecting portion, which is one of the specific locations on the pouring member. In other words, this manufacturing method allows closed cells 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 with a connecting portion having a predetermined thickness that improves ease of opening when one of the inner and outer portions is cut away from the other. Furthermore, because this manufacturing method uses supercritical fluid molding, the inner and outer portions of the pouring member can be formed thinly while maintaining strength, thereby reducing the amount of plastic resin material used.

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 the step (E) of core-backing a second movable mold portion of the mold that corresponds to the flange portion. In this case, core-backing the second movable mold portion facilitates the formation of multiple closed cells within the flange portion, thereby suppressing the occurrence of sink marks that tend to occur when molding a flange portion that has a mixture of thin and thick portions. Therefore, this manufacturing method can produce a pouring member with a flange portion that has high dimensional accuracy. Furthermore, this method for manufacturing a pouring member can increase the dimensional accuracy of the flange portion, thereby improving heat-sealability when attaching the pouring member to another component, such as a container body.

In the above-mentioned manufacturing method for 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 "final thickness" here refers to the thickness of the connecting portion or flange portion when the dispensing member is manufactured using the above-mentioned manufacturing method.

In yet another aspect, the present invention relates to a mold used in the manufacturing method of a dispensing member. This mold is used in any of the manufacturing methods of a dispensing 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 dispensing member using a mold with the above configuration, it is possible to easily provide multiple closed cells with the desired porosity in the connecting portion.

This invention improves the ease of opening when one of the inner and outer portions is cut away from the other.

FIG. 1 is a cross-sectional view showing an example of a cap member according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of the vicinity of the connecting portion S of the cap member shown in FIG. FIG. 3 is a cross-sectional view showing a part (lower die) of a molding die for manufacturing the cap member shown in FIG. 1 by supercritical fluid molding, and the molded cap member. 4A and 4B are cross-sectional views illustrating a method of forming closed cells in the connecting portion by core-backing when molding the cap member shown in FIG. 1 by supercritical fluid molding, in which (a) shows the state of the connecting portion before core-backing, and (b) shows the state of the connecting portion after core-backing. FIG. 5 is a diagram illustrating the thickness of the connecting portion in a conventional cap member.

The following describes in detail a cap member, a method for manufacturing a cap member, and a molding die used in the method for manufacturing a cap member according to one embodiment of the present invention, with reference to the drawings. In the description, the same reference numerals may be used for identical elements or elements with the same functions, and redundant explanations will be omitted. Note that the present invention is not limited to the following embodiment.

Figure 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. Cap member 1 is, for example, a spout with a pull ring or a cap with a pull ring, and is a pouring member that is attached to the opening of a container body (not shown) that contains a predetermined content (e.g., a seasoning). Cap member 1 may be either a stopper-type or a screw-type, and the content stored in the container body to which cap member 1 is attached may be any of food, non-food, powder, and liquid. Cap member 1 may be configured with or without a lid.

As shown in FIG. 1, the cap member 1 comprises 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 from leaking out during transportation or carrying. When using the contents stored in the container body, the inner portion 2 is cut away 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 area where the inner portion 2 was located in the cap member 1. Such a cap member 1 can be manufactured as a single unit by resin molding, as described below.

The inner portion 2 is a generally cylindrical portion with a bottom that is located inside the outer portion 3 and is connected to the outer portion 3 via a connecting portion 4 located on the outside. The inner portion 2 is not connected to the outer portion 3 at any point other than the connecting portion 4. The inner portion 2 is, for example, a pull ring or other component, and functions to close the opening of the container body when the cap member 1 is attached to the container and used for transportation, etc. On the other hand, the inner portion 2 is configured to be cut off from the outer portion 3 by the connecting portion 4 when the contents contained in the container body are used. By cutting off the inner portion 2 from the outer portion 3, the opening of the container body to which the cap member 1 is attached is opened. Note that the inner portion 2 may be configured to fit with a portion extending from the top surface of a lid member (not shown) attached to the cap member 1, so that the inner portion 2 can be cut off from the outer portion 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).

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 connected to the inner portion 2 by a connecting portion 4 provided on its inner circumferential surface, forming an integrated unit. The outer portion 3 is connected to the inner portion 2 only by the connecting portion 4, and is not connected in any other location. 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 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.

The connecting portion 4 connects the inner portion 2 and the outer portion 3 and is the intended cutting area when the inner portion 2 is cut away 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 Figure 2). Having a thickness T of 0.3 mm for the connecting portion 4 prevents 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.

Furthermore, as shown in Figure 2, multiple closed cells 7 are formed inside the connecting portion 4. Closed cells 7 are 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, as described below. 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 no such closed cells are formed in the inner portion 2 or outer portion 3, and they are configured so that parts other than the connecting portion 4 do not become the starting point for cutting.

More specifically, each of the closed bubbles 7 formed in the connecting portion 4 may have a length of 10 μm to 400 μm, 10 μm to 300 μm, or 200 μm to 300 μm, where the length is the longest side passing through the center of gravity of the bubble. The number of bubbles per unit volume of the multiple closed bubbles 7 in the connecting portion 4 may be, for example, ^0.3 to 8.5/mm. If the connecting portion 4 in which the closed bubbles 7 are formed is sufficiently thin (e.g., about ^0.5 mm) to allow light to pass through, the number of bubbles per unit area may be specified. In this case, the number of bubbles per unit area of the multiple closed bubbles 7 in the connecting portion 4 may be 0.1 to ^2.5 /mm ^.

On the other hand, when the cap member 1 is formed from a light-opaque material, 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 may be 0.1 bubbles/ ^mm² or more and 2.5 bubbles/ ^mm² or less, as described above. The number of bubbles may be calculated directly from an image captured using a microscope at a magnification of 35x, for example, or may be calculated by subjecting the obtained image to predetermined image processing. The absence of closed bubbles in the inner portion 2 or the outer portion 3 means that there are no closed bubbles visible to the naked eye, or that the number of bubbles visible per unit area at a magnification of 35x using a microscope is 0.01 bubbles/ ^mm² or less. Generally, the lower limit of the bubble length of bubbles visible to the naked eye is 200 µm, so the phrase "there are no closed bubbles visible to the naked eye" means that there are no bubbles with a length exceeding 200 µm. Furthermore, in terms of determining whether or not closed bubbles have been 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 with a microscope, it is determined that closed bubbles have not been formed as long as the number of bubbles per unit area is 0.01 bubbles/ ^mm2 or less.

In the cap member 1, the presence of these 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 to tear it off, improving ease of opening when tearing the inner portion 2 from the outer portion 3. Furthermore, 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 aesthetically pleasing appearance.

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 portion of a molding die (lower die) used to manufacture the cap member shown in Figure 1 by supercritical fluid molding, and the molded cap member 1. Figure 4 is a cross-sectional view illustrating 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 core backing, and (b) shows the state of the connecting portion 4 after core backing. Figure 5 is a diagram illustrating the thickness of the connecting portion in a conventional cap member.

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 the molten resin composition into the cavity of the 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 using, for example, a MuCell injection molding machine ("MuCell" is a registered trademark of Trexel Co. Ltd.) (see, for example, Japanese Patent No. 6085729 and Japanese Patent No. 6430684).

[(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) refers to 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 shot refers to a phenomenon in which the resin material does not reach the flow end of the cavity.

To mold parts with thin-walled portions using conventional injection molding, it was necessary to select a resin with high fluidity (high MFR value) to prevent short shots. However, highly fluid resin materials tend to have relatively low molecular weights 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 suppress short shots while also achieving excellent strength (for example, buckling strength and drop resistance).

When carbon dioxide is used as the supercritical fluid, the molten resin composition is prepared by adding 1 to 4 parts by mass, preferably 2 to 3 parts by mass, of supercritical carbon dioxide per 100 parts by mass of resin material. 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. In addition, foaming caused by supercritical carbon dioxide can be promoted, for example, at the end of the flow (e.g., flange portion 5 of 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 properties, resulting in an inability to form a uniform bubble layer, resulting in unevenness, or insufficient weight reduction.

When nitrogen is used as the supercritical fluid, the molten resin composition is prepared by adding 0.5 to 1.5 parts by mass of supercritical nitrogen per 100 parts by mass of resin material. Using 0.5 parts by mass or more of nitrogen reduces 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, foaming caused by supercritical nitrogen can be promoted, forming voids inside the molded product. On the other hand, using an amount of nitrogen less than 1.5 parts by mass can impair foaming properties, resulting in an inability to form a uniform bubble layer, resulting in unevenness, or insufficient weight reduction.

The temperature of the molten resin composition (screw cylinder temperature) can be set according to the melting point or MFR of the resin material. When using polypropylene resin, this temperature is preferably approximately 210 to 250°C. When using polyethylene resin, this temperature is preferably approximately 220 to 260°C. When this temperature is above the lower limit, the resin flows more easily within the cavity; on the other hand, when it is below the upper limit, burning of the resin tends to be suppressed.

The molten resin composition may contain components other than the resin material and the supercritical fluid. That is, the molten resin composition may further contain, as needed, for example, fillers, colorants, slip agents, antistatic agents, etc.

[(B) Process]
The molten resin composition prepared in step (A) is injected into the cavity of the molding die M corresponding to the cap member 1 through the gate G. As shown in FIG. 3 , the injection molding is performed with the side corresponding to the inner portion 2 designated as the 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. Meanwhile, a pressure drop is likely to occur at the flange portion 5, which is the flow terminal, as will be described in step (C) below.

The injection speed of the molten resin composition in step (B) is preferably 100 to 400 mm/sec, and more preferably 150 to 200 mm/sec. An injection speed of 100 mm/sec or higher tends to make it easier for the resin to reach the end of the flow, and tends to suppress 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 product. Note that in the method for manufacturing 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.

[(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 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, located at the end of the flow away from the gate, a decrease in dwell pressure is likely to occur, 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.

[(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 4A. This expands the portion 4A corresponding to the connecting portion 4, and multiple closed cells 7 are formed therein, as shown in FIG. 4B. 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 separated as 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.

Here, we will explain the amount of core backing in step (D). Figure 5 shows a conventional cap member 11. As shown in Figure 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 backing, so as shown in Figure 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 expands into the connecting portion 4, achieving thickness T. This results in a thickness that is sufficient to prevent breakage during transportation. The amount of core backing may be set appropriately depending on the shape and number of closed cells 7 formed within 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, if the thickness of the connecting portion 4 is 0.2 mm to 0.3 mm, the amount of core backing may be 0.1 mm or less. A skin layer may be formed on the surface of the core-backed connection.

[(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 drops to approximately 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.

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

In this embodiment, each of the plurality of closed cells 7 preferably has a cell length of 10 μm to 400 μm, where the cell 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 preferably 0.3 to ^8.5 / ^mm3 . In this case, the force required to cut off the connecting portion 4 can be more efficiently reduced, improving openability, while maintaining the desired thickness T of the connecting portion 4.

In addition, 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 when molding the cap member 1, making it possible to produce a cap member 1 with excellent dimensional accuracy. Furthermore, pinholes are prevented from forming in the connecting portion 4, preventing leakage from the cap member 1. Furthermore, breakage of the connecting portion 4 during transportation can be 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 multiple closed bubbles 7, further improves openability.

In addition, in this embodiment, the outer portion 3 has a flange portion 5 for attaching the cap member 1 to the container body, and multiple closed cells may be formed inside the flange portion 5. In this case, the closed cells provided 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 improves heat sealing properties when attached to other members such as the container body.

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 in the molten resin composition and create a finely foamed supercritical fluid in the molten resin composition. This facilitates the formation of multiple closed cells 7 within the connecting portion 4, which is one of the specific locations on the cap member 1. In other words, this manufacturing method allows the closed cells 7 to be formed in the desired location (the connecting portion 4 in this example) rather than throughout the entire cap member 1. 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.

The cap member manufacturing method according to this embodiment may further include a step of core-backing the movable mold corresponding to the flange portion 5 of the molding die M. In this case, core-backing this movable mold makes it possible to easily form multiple closed cells inside the flange portion 5, thereby suppressing the occurrence of sink marks that tend to occur when molding a flange portion that has a mixture of thin and thick portions. Therefore, this manufacturing method makes it possible to obtain a cap member 1 with a flange portion 5 that has high dimensional accuracy. Furthermore, because this cap member manufacturing method can increase the dimensional accuracy of the flange portion 5, it can also improve the heat-sealing properties when attaching the cap member to another member, such as a container body.

Furthermore, in the manufacturing method of the 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 multiple closed cells 7 with the desired porosity in the connecting portion 4, the flange portion 5, etc.

Although the above describes embodiments of the present invention, 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 is described, but this 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, while the above embodiments illustrate the use of carbon dioxide or nitrogen as the supercritical fluid, argon or helium, for example, may be used instead of these gases.

DESCRIPTION OF SYMBOLS 1... Cap member, 2... Inner part, 3... Outer part, 4... Connecting part, 5... Flange part, 7... Closed cell, M... Molding mold, M1, M3... Fixed mold, M2... Movable mold (first movable mold).

Claims (3)

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 . each of the plurality of closed cells formed inside the connecting portion has a cell length of 10 μm or more and 400 μm or less, when the cell length is the longest side passing through the center of gravity of the cell;
the number of the closed cells formed inside the connecting portion per unit volume is 0.3 cells/ ^mm3 or more and 8.5 cells/ ^mm3 or less;
The dispensing member according to claim 1. The thickness of the connecting portion is 0.2 mm to 0.4 mm.
The spout member according to claim 1 or 2.