Double container manufacturing method

Abstract

To provide a double container excellent in manufacturing efficiency.SOLUTION: According to the present invention, a double container includes a container body and a valve member. The container body has an outer shell and an inner bag, and is configured such that the inner bag contracts away from the outer shell as a content decrease. The outer shell has an outside air introduction hole that communicates an intermediate space between the outer shell and the inner bag and an outer space. The valve member is attached to the outside air introduction hole. The valve member includes a valve body and a moving body arranged in the valve body, and is configured to be able to adjust the entry and exit of air between the intermediate space and the external space as the moving body moves. The valve body is made of a valve body resin, the moving body is made of a moving body resin. The valve body resin and the moving body resin are each an olefin resin.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a dual container. [Background technology]

[0002] Patent document 1 discloses a valve member having a valve body and a ball arranged within the valve body, in which the flow of air can be adjusted through a through hole provided in the valve member in accordance with the movement of the movable body, and a double container equipped with the valve member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-034784 A Summary of the Invention [Problem to be solved by the invention]

[0004] The valve member as described in Patent Document 1 is composed of, for example, a ball made of POM (polyoxymethylene) and a valve body made of polypropylene. This valve member is used by being attached to the outside air introduction hole of the container body of the double container.

[0005] Incidentally, in a double container manufacturing line, if a product fails an inspection in a process after the valve member is attached to the container body, the container body is crushed and used to manufacture recycled pellets.

[0006] If POM contains recycled pellets, aldehyde gas derived from POM will be generated when the recycled pellets are melted, so it is undesirable for the recycled pellets to contain POM. On the other hand, before crushing the container body to which the valve member is attached, it is necessary to remove the valve member from the container body.

[0007] We also considered using nylon balls instead of POM, but because nylon has a high melting point of approximately 250°C, there is a problem that the melt-kneadability of the recycled pellets deteriorates if nylon is contained in the recycled pellets. Therefore, the valve member using the nylon balls also needs to be removed from the container body before the container body is crushed.

[0008] On the other hand, since it takes time to remove the valve member from the container body, the manufacturing efficiency decreases.

[0009] The present invention has been made in view of the above circumstances, and provides a double container that can be produced with excellent efficiency. [Means for solving the problem]

[0010] According to the present invention, there is provided a double container comprising a container body and a valve member, wherein the container body has an outer shell and an inner bag and is configured so that the inner bag separates from the outer shell and shrinks as the contents decrease, the outer shell has an outside air inlet hole connecting an intermediate space between the outer shell and the inner bag with an outside space, the valve member is attached to the outside air inlet hole, the valve member comprises a valve body and a moving body arranged within the valve body and is configured to be able to adjust the flow of air in and out between the intermediate space and the outside space as the moving body moves, the valve body is made of valve body resin and the moving body is made of moving body resin, and the valve body resin and the moving body resin are each an olefin-based resin.

[0011] In the double container of the present invention, since both the valve body resin and the movable body resin are olefin-based resins, they do not generate aldehyde gases even when heated, and their melting point is not as high as that of nylon. Therefore, it is not necessary to remove the valve member from the container body before crushing the container body, which results in excellent manufacturing efficiency.

[0012] Various embodiments of the present invention will be described below. The embodiments described below can be combined with each other. Preferably, in the above-described double container, the valve body resin and the movable body resin have a common monomer unit ratio of 50% by mass or less. Preferably, in the above-described double container, the valve body resin has a Vicat softening point of 115° C. or higher. Preferably, in the above-described double container, the valve body resin has a flexural modulus of elasticity of 500 to 1500 MPa. Preferably, in the above-described double container, the movable body resin is polypropylene and the valve body resin is high density polyethylene. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a front view of a double container 1 according to one embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view showing a main part, including a valve member 4, of a container body 3 of the double container 1 of FIG. [Diagram 3] 3A is a perspective view of the valve body 5 of the valve member 4 in FIG. 2 as viewed from above, and FIG. 3B is a perspective view of the valve body 5 as viewed from below. [Figure 4] 4A is a plan view of the valve body 5 of FIG. 2, and FIG. 4B is a bottom view of the valve body 5. As shown in FIG. [Diagram 5] 5A is a cross-sectional view taken along line AA in FIG. 4A, and FIG. 5B is a cross-sectional view taken along line BB in FIG. 4A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present invention will be described. Various features shown in the following embodiments can be combined with each other. Also, each feature can be an invention independently.

[0015] 1. Configuration of double container 1 As shown in Fig. 1, a double container 1 according to one embodiment of the present invention comprises a cap 2, a container body 3, and a valve member 4. The container body 3 comprises a storage section 7 for storing the contents, and a mouth section 9 for discharging the contents from the storage section 7. In this embodiment, the cap 2 is of a screw type, but it may also be of a stopper type. The cap 2 can be attached after the container body 3 is filled with the contents.

[0016] As shown in FIG. 2, the container body 3 has an outer layer 11 and an inner layer 13 in the storage section 7 and the mouth section 9, the outer layer 11 forming an outer shell 12, and the inner layer 13 forming an inner bag 14. As the content in the inner bag 14 decreases, the inner layer 13 peels off from the outer layer 11, and the inner bag 14 separates from the outer shell 12 and shrinks. Regarding the layer structure of the container body 3, the outer layer 11 is formed to be thicker than the inner layer 13 so as to have high restorability. The outer layer 11 is composed of, for example, low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, ethylene-propylene copolymer, and mixtures thereof. The outer layer 11 may be composed of multiple layers. It is preferable that the inner layer 13 is composed of multiple layers. For example, an EVOH layer made of an ethylene-vinyl alcohol copolymer (EVOH) resin can be used as the layer in contact with the outer layer, and an inner layer made of a polyolefin such as low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, an ethylene-propylene copolymer, or a mixture thereof can be used as the layer in contact with the contents. An adhesive layer is preferably used between the EVOH layer and the inner layer.

[0017] As shown in Fig. 2, the outer shell 12 is provided with an outside air introduction hole 15 that communicates the intermediate space 21 between the outer shell 12 and the inner bag 14 with the outside space S. The outside air introduction hole 15 is a through hole provided only in the outer shell 12 and does not reach the inner bag 14. The outside air introduction hole 15 is provided in the storage section 7 (more specifically, the valve member attachment recess 7a). The valve member 4 is attached to the outside air introduction hole 15.

[0018] 2, the valve member 4 includes a valve body 5 and a movable body 6 disposed within the valve body 5. The valve member 4 is configured so that the inflow and outflow of air between the intermediate space 21 and the external space S can be adjusted in accordance with the movement of the movable body 6. The valve member 4 can be attached by being pushed into the external air introduction hole 15 from the outside of the container body 3.

[0019] As shown in FIG. 2, FIG. 3A, and FIG. 3B, the valve body 5 has a cavity 50 provided so as to communicate the intermediate space 21 with the external space S. The moving body 6 is movably accommodated in the cavity 50. The moving body 6 is preferably spherical. The diameter of the moving body 6 (the maximum diameter of the moving body 6 on a plane perpendicular to the moving direction of the moving body 6) is, for example, 1 / 32 to 5 / 32 inches, specifically, for example, 1 / 32, 2 / 32, 3 / 32, 4 / 32, or 5 / 32 inches, and may be within a range between any two of the numerical values ​​exemplified here. If the diameter of the moving body 6 is too large, the outside air introduction hole 15 becomes large accordingly, and the stability of the hole opening when forming the outside air introduction hole 15 may decrease. If the diameter of the moving body 6 is too small, the moving body 6 may be difficult to handle.

[0020] The valve body 5 and the moving body 6 are formed by injection molding or the like. The valve body 5 is made of a valve body resin, and the moving body 6 is made of a moving body resin. The valve body resin and the moving body resin are both olefin-based resins. Olefin-based resins do not generate aldehyde gases even when heated, and their melting point is not as high as that of nylon. For this reason, in the recycling process described below, it is not necessary to remove the valve member 4 from the container body 3 before crushing the container body 3 to which the valve member 4 is attached, so the manufacturing efficiency of the double container 1 is superior to the case of using a moving body 6 made of POM or nylon.

[0021] The olefin resin is a resin in which the olefin unit is 50% by mass or more. Examples of olefins include ethylene and propylene. The ratio of the olefin unit contained in the olefin resin is, for example, 50 to 100% by mass, specifically, for example, 50, 60, 70, 80, 90, or 100% by mass, and may be within a range between any two of the numerical values ​​exemplified here. Examples of the olefin resin include low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, and copolymers of propylene and other olefins (such as ethylene) (random copolymers or block copolymers. Hereinafter, the random copolymers are referred to as "random polypropylenes"). The specific gravity of the high-density polyethylene is preferably 0.932 or more, more preferably 0.938 or more, and more preferably 0.942 or more, and is preferably 0.970 or less, and more preferably 0.960 or less.

[0022] The proportion of the common monomer units in the valve body resin and the moving body resin is preferably 50% by mass or less. If the proportion of the common monomer units in the valve body resin and the moving body resin is too high, the valve body 5 and the moving body 6 are likely to stick to each other, causing malfunction of the valve member 4. However, if the proportion of the common monomer units in the valve body resin and the moving body resin is 50% by mass or less, the valve body 5 and the moving body 6 are unlikely to stick to each other, and malfunction of the valve member 4 is suppressed. For example, if the valve body resin is random polypropylene (propylene content 95% by mass) and the moving body resin is polypropylene (propylene homopolymer), the proportion of the common monomer units is 95% by mass. On the other hand, if the valve body resin is high-density polyethylene (propylene content 0% by mass) and the moving body resin is polypropylene, the proportion of the common monomer units is 0% by mass. In the former case, the valve body 5 and the moving body 6 are likely to stick to each other, and in the latter case, the valve body 5 and the moving body 6 are unlikely to stick to each other. The proportion of the common monomer units is, for example, 0 to 50% by mass, specifically, for example, 0, 10, 20, 30, 40, or 50% by mass, and may be within a range between any two of the numerical values ​​exemplified here.

[0023] The valve body resin preferably has a Vicat softening point of 115°C or higher. If the Vicat softening point is too low, the valve body 5 is likely to deform during high-temperature storage or when filled with high-temperature contents, and the valve function is likely to deteriorate. The Vicat softening point is, for example, 115 to 150°C, specifically, for example, 115, 120, 125, 130, 135, 140, 145, or 150°C, and may be within a range between any two of the values ​​exemplified here or equal to or higher than any one of them. The Vicat softening point can be measured in accordance with JIS K7206.

[0024] The valve body resin preferably has a flexural modulus of 500 to 1500 MPa. If the flexural modulus of the valve body resin is too low, the valve body 5 is deformed when a load is applied to the valve member 4, and the valve function is likely to deteriorate. If the flexural modulus of the valve body resin is too high, as described below, when the moving body 6 is inserted into the cavity portion 50 while the valve body 5 is elastically deformed, the valve body 5 is difficult to deform, and the insertion of the moving body 6 may be difficult. Specifically, the flexural modulus is, for example, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, or 1500 MPa, or may be in a range between any two of the numerical values ​​exemplified here. The flexural modulus can be measured in accordance with JIS K6922-2.

[0025] The valve body resin preferably has a melting point of 130°C or higher. If the melting point is too low, the valve body 5 is likely to deform during high-temperature storage or when filled with high-temperature contents, and the valve function is likely to deteriorate. The melting point is, for example, 130 to 160°C, specifically, for example, 130, 135, 140, 145, 150, 155, or 160°C, and may be within a range between any two of the values ​​exemplified here or any value higher than that. The "melting point" refers to the melting peak temperature Tpm measured according to JIS K 7121:2012.

[0026] As shown in Figs. 3A to 5B, the valve body 5 has a narrow-diameter shaft portion 51 disposed in the outside air introduction hole 15, a disk-shaped locking portion 52 provided on the outside space S side of the shaft portion 51 and preventing the valve body 5 from entering the intermediate space 21, and a bulging portion 53 provided on the intermediate space 21 side of the shaft portion 51 and preventing the valve body 5 from being pulled out from the outside of the container body 3. An opening 52o connected to the cavity 50 is formed on the upper surface 52u of the locking portion 52 (i.e., the outer surface of the valve body 5 on the outside space S side), and an adjacent region 52a is formed around the opening 52o. The adjacent region 52a is a circular flat region. In addition, an annular protruding region 52p protruding from the adjacent region 52a to the outside space S side is formed on the upper surface 52u of the locking portion 52 outside the adjacent region 52a.

[0027] The hollow portion 50 is a hole penetrating the valve body 5 in the axial direction (direction perpendicular to the outside air introduction hole 15), and has a shape narrower on the intermediate space 21 side and the external space S side in the axial direction than on the central portion in order to accommodate the spherical moving body 6. Specifically, as shown in Figures 5A and 5B, the portion of the hollow portion 50 on the intermediate space 21 side corresponding to the inside of the locking portion 52 has a truncated cone shape with a diameter decreasing toward the external space S side, and a stopper portion 52s that locks the moving body 6 to block the flow of air is formed over the circumferential direction.

[0028] A pair of holding portions 53p are formed at two opposing positions on the intermediate space 21 side of the hollow portion 50, protruding radially inward to hold the movable body 6 housed in the hollow portion 50 (see Figs. 3B and 5A). In this embodiment, the holding portion 53p has an inclined surface 53p1 inclined toward the external space S side, and the movable body 6 abuts against the inclined surface 53p1 to hold the movable body 6. As shown in Fig. 5A, the holding portion 53p also has an inclined surface 53p2 on the intermediate space 21 side that is inclined toward the intermediate space 21 side.

[0029] As shown in Figures 3B and 4B, the tip portion of the valve body 5 (the end portion of the expanded diameter portion 53) has a circular flat surface 53e, and notches 53n are provided in two opposing circumferential locations by cutting out the flat surface 53e.

[0030] The movable body 6 is inserted into the cavity 50 of the valve body 5 from the intermediate space 21 side (the expanded diameter portion 53 side) while elastically deforming the valve body 5. The valve body 5 is provided with a holding portion 53p, which has an inclined surface 53p2, so that the movable body 6 can be inserted into the cavity 50 by climbing over the holding portion 53p.

[0031] The valve member 4 configured as described above can be attached to the container body 3 by inserting the expanded diameter portion 53 into the intermediate space 21 while the expanded diameter portion 53 pushes open the outside air introduction hole 15. When the valve member 4 is pushed into a position where the locking portion 52 abuts against the outer surface of the outer shell 12, the valve member 4 is held by the outer shell 12 with the outer peripheral surface of the shaft portion 51 in close contact with the edge of the outside air introduction hole 15. By having the outer peripheral surface of the shaft portion 51 in close contact with the edge of the outside air introduction hole 15, air in the intermediate space 21 is prevented from leaking out from the gap between the edge of the outside air introduction hole 15 and the valve body 5 when the container body 3 is compressed.

[0032] The valve body 5 is attached to the container body 3 by the outer circumferential surface of the shaft portion 51 coming into close contact with the edge of the outside air introduction hole 15, so the expanded diameter portion 53 is not necessarily required. Also, since the flat surface 53e is provided at the tip of the valve body 5, the inner bag 14 is less likely to be damaged even if the tip of the valve member 4 hits the inner bag 14 when the valve member 4 is pushed into the intermediate space 21. In addition, in this embodiment, the stopper portion 52s is formed inside the locking portion 52 shifted from the shaft portion 51 toward the external space S, so that even if the shaft portion 51 is pressed by the edge of the outside air introduction hole 15, the stopper portion 52s will not deform, and it is possible to appropriately block the flow of air.

[0033] When outer shell 12 is compressed with air in intermediate space 21, the air in intermediate space 21 enters hollow portion 50 from expanded diameter portion 53 and pushes movable body 6 up and into contact with stopper portion 52s. When movable body 6 is stopped by stopper portion 52s, the flow of air through hollow portion 50 is blocked. When outer shell 12 is further compressed in this state, the pressure in intermediate space 21 increases, and as a result, inner bag 14 is compressed and the contents in inner bag 14 are expelled.

[0034] Furthermore, when the compressive force on the outer shell 12 is released, the outer shell 12 tries to restore its original shape due to its own elasticity. As the outer shell 12 restores its original shape, the pressure in the intermediate space 21 is reduced, and a force is applied to the moving body 6 toward the inside of the container. This causes the moving body 6 to move toward the bottom of the hollow portion 50, and outside air is introduced into the intermediate space 21 through the gap between the moving body 6 and the wall surface that forms the hollow portion 50.

[0035] 2. Manufacturing method of double container 1 Next, a method for manufacturing the double container 1 of this embodiment will be described. This method includes a container body forming step, a valve member mounting step, a quality determining step, and a recycling step. Each step will be described below.

[0036] <Container body formation process> In the container body forming process, the container body 3 having the outside air introduction hole 15 is formed. The container body 3 can be formed by blow molding of a parison. The blow molding may be direct blow molding or injection blow molding. In direct blow molding, the container body 3 is manufactured by sandwiching a molten cylindrical parison extruded from an extruder between a pair of split dies and blowing air into the parison. In injection blow molding, a test tube-shaped parison with a bottom called a preform is formed by injection molding, and the container body 3 is manufactured by blow molding using this parison. The outside air introduction hole 15 may be formed by performing post-processing on the molded body obtained by blow molding, or a through hole previously formed in the preform may be used as the outside air introduction hole 15.

[0037] In the container body forming process, a preliminary peeling process may be performed on the container body 3, in which the inner bag 14 is peeled off from the outer shell 12. This makes it easier for the inner bag 14 to separate from the outer shell 12 and shrink after the contents are filled. The preliminary peeling process is preferably performed after or simultaneously with the formation of the outside air introduction hole 15.

[0038] <Valve member installation process> In the valve member mounting step, the valve member 4 is mounted in the outside air introduction hole 15. The valve member 4 can be mounted by pushing it into the outside air introduction hole 15 from the outside of the container body 3.

[0039] <Good / bad judgment process> In the pass / fail determination process, a pass / fail determination is made on the container body 3 (hereinafter also referred to as the "product") fitted with the valve member 4. The pass / fail determination can be made based on the results of various inspections made on the container body 3 fitted with the valve member 4. The inspections include an appearance inspection (whether the appearance is good), an air leak inspection (whether there is any air leak from the inner bag 14), a valve function inspection (whether the valve member 4 is functioning properly), a weight inspection (whether the weight is appropriate), and the like.

[0040] Products that pass the quality check are shipped. Products that fail the quality check are not shipped and are sent to the recycling process.

[0041] <Recycling process> In the recycling process, the product is crushed to form recycled pellets. In this embodiment, since the valve member 4 is made of an olefin resin, the recycling process can be performed without removing the valve member 4 from the container body 3, resulting in excellent manufacturing efficiency. EXAMPLES

[0042] 1. Manufacturing of double container 1 <Example 1> A container body 3 having the shape shown in FIG. 1 was formed by direct blow molding, and an outside air introduction hole 15 was formed. Next, polypropylene (Prime Polymer Co., Ltd., Prime Polypro, J105G, tensile modulus 1650 MPa) was used as the moving body resin, and high density polyethylene (Japan Polyethylene, Novatec, HJ362, flexural modulus 820 MPa, melting point 132°C, Vicat softening point 123°C) was used as the valve body resin to form a valve member 4 having the shape shown in FIG. 2-FIG. 3, which was then inserted into the outside air introduction hole 15. Next, the inner bag 14 was filled with the contents at 90°C, and then the cap 2 having a check valve was attached to the mouth 9 of the container body 3 to obtain a double container 1. A spherical moving body 6 having a diameter of 3 / 32 inch was used.

[0043] <Example 2> A double container 1 was obtained in the same manner as in Example 1, except that a random polypropylene (SunAllomer Co., Ltd., SunAllomer, PM731M, tensile modulus 900 MPa) was used as the valve body resin.

[0044] <Example 3> A double container 1 was obtained in the same manner as in Example 1, except that linear low-density polyethylene (Japan Polyethylene, Novatec, UJ990, flexural modulus 440 MPa, melting point 128°C, Vicat softening point 113°C) was used as the valve body resin.

[0045] 2. Valve function evaluation Ten samples of each of the double containers 1 in Examples 1 to 3 were prepared, and an evaluation was carried out to confirm whether the valve member 4 operated appropriately when discharging the contents in each of the double containers 1.

[0046] As a result, the valve member 4 operated properly in all samples of the double container 1 of Example 1. In the double containers 1 of Examples 2 and 3, although the valve member 4 operated, there were some samples in which the movable body 6 was difficult to move and the valve member 4 had poor sealing performance compared to the sample of Example 1. [Explanation of symbols]

[0047] 1:Double container 2: Cap 3: Container body 4: Valve member 5: Valve body 6: Moving object 7: Storage section 7a: Valve member mounting recess 9: Mouth 11: Outer layer 12: Outer shell 13: Inner layer 14: Inner bag 15: Outside air intake 21: Intermediate space 50: Cavity 51: Shaft 52: Locking part 52a: Adjacent area 52o: opening 52p:Protruding area 52s: Stopper part 52u:Top surface 53: Expansion part 53e :Flat surface 53n :Notch 53p: Holding part 53p1: Inclined surface 53p2: Inclined surface S: External space

Claims

1. A method for manufacturing a double-walled container, comprising a container body forming process, a valve member mounting process, a quality determination process, and a recycling process, In the container body forming step, a container body having an outside air introduction hole is formed, The container body has an outer shell and an inner bag, and is configured so that the inner bag separates from the outer shell and shrinks as the contents decrease; the outside air introduction hole is provided in the outer shell so as to communicate an intermediate space between the outer shell and the inner bag with an outside space, In the valve member mounting step, a valve member is mounted in the outside air introduction hole, The valve member includes a valve body and a movable body disposed within the valve body, and is configured to be capable of adjusting the flow of air between the intermediate space and the external space in accordance with the movement of the movable body; The valve body is made of a valve body resin, The movable body is made of a movable body resin, The valve body resin and the movable body resin are each an olefin-based resin, In the quality determination step, a quality determination is performed on a product obtained by attaching the valve member to the container body, In the recycling step, the products that are determined to be non-conforming are crushed to form recycled pellets, The method for manufacturing a double container, wherein the recycling step is performed without removing the valve member from the container body.

2. A method for manufacturing the double container according to claim 1, The movable body resin is polypropylene, The method for producing a double container, wherein the valve body resin is high-density polyethylene.

3. A method for manufacturing a double container according to claim 1 or claim 2, comprising: A method for manufacturing a double container, wherein the maximum diameter of the moving body in a plane perpendicular to the moving direction of the moving body is 1 / 32 to 5 / 32 inches.

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