JP2024017199A - Double container manufacturing method - Google Patents

Abstract

An object of the present invention is to provide a method for manufacturing a double-layered container in which an inner bag can be smoothly pulled out even in a double-layered container manufactured by performing biaxial stretch blow molding using an inner preform formed by direct blow molding. According to the present invention, a preform consisting of an inner preform and an outer preform is biaxially stretch blow molded to produce a container body having an inner bag and an outer shell covering the inner bag. A method for manufacturing a double container, comprising: the inner preform being formed by direct blow molding using a molten cylindrical parison; An engaging portion used for pulling out the inner bag is provided, the outer diameter of the portion of the inner preform with the largest outer diameter at the mouth is D1, and the outer diameter of the cylindrical parison is D3, A method is provided in which D1/D3 is 1.5 or more, and the opening end of the inner preform is provided with an enlarged diameter structure that suppresses deformation of the mouth. [Selection diagram] Figure 1

Description

The present invention relates to a method for manufacturing a double container.

2. Description of the Related Art Conventionally, double containers are known that include a container body having an outer shell and an inner bag. For example, Patent Document 1 includes a step of biaxially stretch blow molding a preform formed by covering an inner preform with an outer preform to produce a container body having an inner bag and an outer shell covering the inner bag. A method of manufacturing a double container is disclosed.

JP 2019-10741 Publication

By the way, it is conceivable that an engaging part used for pulling out the inner bag from the container body is provided at the mouth of the inner preform, and a member such as a cap is engaged with the engaging part to pull out the inner bag. . In this case, it is desired that the opening of the inner bag has a certain degree of rigidity.

On the other hand, when forming the inner preform by direct blow molding as in Patent Document 1, it is difficult to increase the thickness of only the mouth part of the inner preform, so in order to make the inner bag thinner, the inner preform When the body and bottom of the bag are made thinner, the wall thickness of the mouth of the inner preform becomes smaller, and the rigidity of the mouth of the inner preform becomes insufficient.As a result, the mouth of the inner bag becomes thinner. The rigidity may also become insufficient, which may cause difficulty in pulling out the inner bag. This problem is particularly noticeable when the blow ratio at the mouth of the inner preform is 1.5 times or more.

The present invention was made in view of these circumstances, and it is possible to smoothly pull out the inner bag even in a double-layered container manufactured by performing biaxial stretch blow molding using an inner preform formed by direct blow molding. The present invention provides a method for manufacturing double containers that is possible.

According to the present invention, the following inventions are provided.
[1] A double container comprising the step of biaxially stretching blow molding a preform consisting of an inner preform covered with an outer preform to produce a container body having an inner bag and an outer shell covering the inner bag. In the manufacturing method, the inner preform is formed by direct blow molding using a molten cylindrical parison, and a mouth part of the inner preform is provided for use in pulling out the inner bag from the container body. If the outer diameter of the portion of the inner preform with the largest outer diameter at the mouth is D1, and the outer diameter of the cylindrical parison is D3, then D1/D3 is 1. 5 or more, and the opening end of the inner preform is provided with an enlarged diameter structure that suppresses deformation of the mouth.
[2] The method according to [1], wherein D1/D3 is 2 or more.
[3] The method according to [1] or [2], wherein the inner preform has a wall thickness of 1.5 mm or less at the open end.
[4] The method according to any one of [1] to [3], wherein the total height of the inner preform is H, and the height of the inner preform from the bottom is 0.1H. The method, wherein D2/D1 is 0.35 or more, where D2 is the outer diameter of the inner preform at the position.
[5] The method according to any one of [1] to [4], wherein D2/D1 is 0.5 or more.
[6] The method according to any one of [1] to [5], wherein in the direct blow molding, a molded body having a shape in which a bag portion is connected to an open end of the inner preform is formed, The method wherein the inner preform is formed by cutting the bladder from the molded body.

In the present invention, the open end of the inner preform is provided with an enlarged diameter structure that suppresses deformation of the mouth portion. Since the shape of the mouth of the inner preform changes little or not at all during biaxial stretch blow molding, the opening end of the inner bag is also provided with a diameter-enlarging structure to suppress deformation of the mouth. If the open end of the inner bag is easily deformed, it may become difficult to pull out the inner bag, but with the present invention, deformation of the open end of the inner bag is suppressed, making it possible to pull out the inner bag smoothly. Become.

FIG. 1 is a perspective view of a double container 1 according to a first embodiment of the present invention. The dashed-dotted line in the figure represents the boundary line where the curvature of the surface forming the surface shape changes. The same applies to other figures. FIG. 2 is an exploded perspective view of FIG. 1; 3 is an enlarged view of area A in FIG. 2. FIG. FIG. 4 is an exploded perspective view of FIG. 3; Only a portion of the inner bag 4 near the open end 5c is shown. FIG. 3 is a perspective view of the vicinity of the open end of the outer shell 3. FIG. It is a perspective view of the overcap 27 and the inner stopper 26 viewed diagonally from below. FIG. 7A shows a state in which the inner plug 26 is attached to the inner bag 4. The inner bag 4 is a perspective view showing the vicinity of the opening 5, and the inner plug 26 is a vertical cross-sectional perspective view. FIG. 7B is a vertical cross-sectional perspective view of the inner stopper 26. 2 is a longitudinal sectional view passing through the center of the mouth portion 5 of the double container 1 shown in FIG. 1 before opening the overcap 27. FIG. FIG. 3 is a front view of a state in which a shrink film 33 is attached to cover the container body 2 and the mouth attachment member 8; FIG. 2 is a perspective view of the container body 2 viewed from below. FIG. 2 is a longitudinal cross-sectional view passing through the center of the mouth portion 5 of the container body 2. FIG. 12A to 12C are a sectional view taken along line AA, line BB, and line CC in FIG. 11, respectively. 12C is a sectional view corresponding to FIG. 12C showing that a bent shape 2c is likely to be formed when the inner bag 4 is rotated with respect to the outer shell 3. FIG. FIG. 4 is a perspective view of the inner bag 4 with a cap 8a attached thereto. FIG. 4 is a diagram showing the layered structure of the inner bag 4. FIG. FIG. 3 is a perspective view showing a state in which the inner preform 14 and the outer preform 13 are separated. 17A is a front view of the inner preform 14, FIG. 17B is a right side view of the inner preform 14, and FIGS. 17C to 17D are perspective views of the vicinity of the bottom of the inner preform 14 seen diagonally from below. It is a diagram. FIG. 2 is a perspective view showing a preform 15 configured by covering an inner preform 14 with an outer preform 13. FIG. 3 is a cross-sectional view of a cylindrical parison 34 disposed between split molds 35 and 36 in an open state. FIG. 3 is a cross-sectional view after a molded body 38 is formed by closing the split molds 35 and 36 and blowing air into them. FIG. 21A is a cross-sectional view showing the state after the molded body 38 is taken out from the split molds 35, 36 and the burr 39 is removed from the state shown in FIG. FIG. 21B is an enlarged view of region B in FIG. 21A. FIG. 22A is a cross-sectional view showing the state after the bag portion 40 is cut out from the state shown in FIG. 21 to form the inner preform 14. FIG. 22B is an enlarged view of region B in FIG. 22A. FIG. 22C is a diagram corresponding to FIG. 22B when the burr 14p remains at the open end of the inner preform 14. FIG. 23A is an enlarged view of a portion corresponding to region A in FIG. 22A in a form in which the protruding seal portion 42 is not provided with a stretch restraining structure. FIG. 23B shows a portion corresponding to FIG. 23A after biaxial stretch blow molding. FIG. 24A is an enlarged view of region A in FIG. 22A. FIG. 24B shows a state after the protruding seal portion 42 is bent to form a stretch suppressing structure from the state of FIG. 24A, and FIG. 24C shows a biaxial stretch blow molding of the inner preform 14 into which the stretch suppressing structure has been introduced. The corresponding part is shown in FIG. 24B after this. FIG. 25A is a perspective view of the vicinity of the bottom of the inner preform 14 in the second embodiment of the present invention. FIG. 25B is a cross-sectional view of the inner preform 14 in FIG. 25A, taken in a section perpendicular to the longitudinal direction of the protruding seal portion 42. FIG. FIG. 25C is an enlarged view of region C in FIG. 25B. In this form, the protruding seal portion 42 has a stretching suppressing structure without any post-processing. FIG. 26A is a perspective view of the vicinity of the bottom of the inner preform 14 in the third embodiment of the present invention. FIG. 26B is a cross-sectional view of the inner preform 14 in FIG. 26A, taken in a cross section perpendicular to the longitudinal direction of the protruding seal portion 42. FIG. 26C is an enlarged view of region C in FIG. 26B. FIG. 26D shows a state after the protruding seal portion 42 in FIG. 26C is remelted to form a stretch restraining structure. FIG. 27A is a perspective view of the vicinity of the bottom of the inner preform 14 in the fourth embodiment of the present invention. FIG. 27B is a cross-sectional view of the inner preform 14 in FIG. 27A, taken in a section perpendicular to the longitudinal direction of the protruding seal portion 42. FIG. 27C is an enlarged view of region C in FIG. 27B. FIG. 27D shows a state after the protruding seal portion 42 in FIG. 27C is bent to form a stretch restraining structure. FIG. 28A is a perspective view of the vicinity of the bottom of the inner preform 14 in the fifth embodiment of the present invention. FIG. 28B is a cross-sectional view of the inner preform 14 in FIG. 28A, taken in a cross section perpendicular to the longitudinal direction of the protruding seal portion 42. FIG. 28C is an enlarged view of region C in FIG. 28B. FIG. 28D shows a state after the protruding seal portion 42 in FIG. 28C is bent to form a stretch restraining structure. It is a perspective view of the inner preform 14 in 6th Embodiment of this invention. It is a perspective view of the inner preform 14 and the outer preform 13 in 7th Embodiment of this invention. It is a perspective view of the inner preform 14 and the outer preform 13 having the same configuration as the seventh embodiment of the present invention, except that the protruding seal portion 42 does not have a stretch suppressing structure.

Embodiments of the present invention will be described below. Various features shown in the embodiments described below can be combined with each other. Further, the invention can be realized independently for each feature.

In the embodiments shown below, the inventions of the first to ninth aspects are disclosed, and the claims relate to at least a portion thereof. The first to fifth embodiments are related to the first to ninth aspects. The sixth to seventh embodiments are related to the first to third and fifth to ninth aspects.

(First perspective)
In this aspect, the double container includes the step of biaxially stretching blow molding a preform formed by covering an inner preform with an outer preform to produce a container body having an inner bag and an outer shell covering the inner bag. In the manufacturing method, the inner preform is formed by direct blow molding using a molten cylindrical parison, and the inner preform is formed by welding the inner surfaces of the cylindrical parison to each other. A protruding seal portion is provided in which the seal portion protrudes from the main body portion of the inner preform, and the protruding seal portion includes a stretch suppressing structure that suppresses stretching of the seal portion during the biaxial stretch blow molding. A method is provided.

(Second perspective)
In this aspect, the double container includes the step of biaxially stretching blow molding a preform formed by covering an inner preform with an outer preform to produce a container body having an inner bag and an outer shell covering the inner bag. In the manufacturing method, the inner preform is formed by direct blow molding using a molten cylindrical parison, and a mouth part of the inner preform is provided for pulling out the inner bag from the container body. An engaging portion to be used is provided, the outer diameter of the portion of the inner preform with the largest outer diameter at the mouth is D1, the total height of the inner preform is H, and the height from the bottom of the inner preform is Provided is a method in which D2/D1 is 0.35 or more, where D2 is the outer diameter of the inner preform at a height of 0.1H.

(Third viewpoint)
In this aspect, the double container includes the step of biaxially stretching blow molding a preform formed by covering an inner preform with an outer preform to produce a container body having an inner bag and an outer shell covering the inner bag. In the manufacturing method, the inner preform is formed by direct blow molding using a molten cylindrical parison, the inner bag includes a thin wall portion having a wall thickness of 100 μm or less, and the inner preform is formed by direct blow molding using a molten tubular parison. provides a method in which an uneven shape is provided or a lubricant is present on the outer surface of a region including a region corresponding to the thin-walled region.

(Fourth viewpoint)
In this aspect, the double container includes the step of biaxially stretching blow molding a preform formed by covering an inner preform with an outer preform to produce a container body having an inner bag and an outer shell covering the inner bag. In the manufacturing method, the inner preform is formed by direct blow molding using a molten cylindrical parison, and a mouth part of the inner preform is provided for pulling out the inner bag from the container body. If the outer diameter of the portion of the inner preform where the engaging portion is provided and has the largest outer diameter at the mouth is D1, and the outer diameter of the cylindrical parison is D3, then D1/D3 is 1. .5 or more, and the opening end of the inner preform is provided with an enlarged diameter structure that suppresses deformation of the mouth.

(Fifth viewpoint)
In this aspect, the double container includes a container body and a mouth attachment member, the container body includes an inner bag, an outer shell disposed to cover the inner bag, and the mouth attachment member. The member is attached to the mouth of the container body in a plugging type, and the inner bag is moved in a direction in which the inner bag is removed from the container body by rotating the mouth attachment member with respect to the outer shell. A double container is provided, configured to:

(Sixth viewpoint)
In this aspect, the double container is provided with a container body, a mouth attachment member, and a shrink film attached to cover the container body and the mouth attachment member, and the container body includes an inner bag and an inner bag. , an outer shell disposed to cover the inner bag; the mouth attachment member includes an inner plug and an overcap; the inner plug is attached to the mouth of the inner bag in a circumferential direction and an axial direction; The overcap is engaged with the inner plug, and by rotating the inner plug with respect to the outer shell, the inner bag moves in a direction in which it comes out of the container body. The shrink film may be installed in a covered state covering the container body and the inner stopper but not the overcap, or the shrink film may be placed in the covered state after removing a portion of the shrink film. A double container is provided in which an easy-to-cut line is provided so that the container can be easily cut.

(Seventh viewpoint)
In this aspect, there is provided a method for discharging contents in a double container, wherein the double container includes a container body and a cap attached to the mouth of the container body, and the container body includes an inner bag and a cap attached to the mouth of the container body. , an outer shell disposed to cover the inner bag, the contents being housed in the inner bag, the cap being engaged with the inner bag, and a drawing process and a dispensing process. In the drawing step, the inner bag is pulled out from the container body while the cap is engaged with the inner bag with a portion of the contents remaining in the inner bag, In the discharging step, a method is provided in which the contents remaining in the inner bag are discharged after the inner bag is pulled out from the container main body.

(Eighth viewpoint)
In this aspect, the double container includes a container body, the container body includes an inner bag, and an outer shell arranged to cover the inner bag, and if the total height of the container body is J, In a cross section at a position 0.2J from the bottom surface of the container body, the container body has three or more corner portions spaced apart in the circumferential direction, and there is a space between the corner portions. , a double container is provided, which is provided with a connecting portion having a larger radius of curvature than the corner portion.

(9th viewpoint)
In this aspect, the double container includes a container body, the container body includes an inner bag, and an outer shell disposed to cover the inner bag, and the inner bag is located inside the container body. A double container is provided which includes, in order from the above, an inner layer, a gas barrier layer, and an outer layer.

1. First embodiment 1-1. Configuration of double container 1 <Basic configuration>
As shown in FIG. 1, the double container 1 according to the first embodiment of the present invention includes a container body 2 and a mouth attachment member 8.

As shown in FIGS. 2 and 3, the container body 2 includes a mouth portion 5, a body portion 6, and a bottom portion 7. The mouth portion 5 is a cylindrical (preferably cylindrical) portion having an open end 5c. The mouth part 5 includes an engaging part 4m to which a mouth part attachment member 8 such as a cap or a pump can be attached. Details of the engaging portion 4m will be described later. The mouth portion 5 is provided with a flange 5b. The flange 5b can be used to support the mouth part 5 when the mouth part mounting member 8 is attached to the mouth part 5.

The body portion 6 is disposed adjacent to the mouth portion 5 on a side further away from the opening end 5c than the mouth portion 5. The body portion 6 has a larger outer diameter (in this specification, “outer diameter” means an equivalent circle diameter when the cross section is not circular) than the mouth portion 5. The body 6 has a cylindrical shape, and the bottom 7 is provided at the lower end of the body 6 and closes the lower end of the body 6. The body portion 6 includes a shoulder portion 6b whose outer diameter increases as the distance from the mouth portion 5 increases. Further, the trunk 6 includes a trunk main body 6c closer to the bottom 7 than the shoulder 6b. The trunk main body 6c has, for example, a shape in which the outer diameter is substantially constant toward the bottom 7, or a shape in which the outer diameter decreases toward the bottom 7.

As shown in FIG. 4, the container body 2 includes an inner bag 4 and an outer shell 3 disposed to cover the inner bag 4. In the inner bag 4, the inner bag main body 4d other than the protrusion 4c is housed in the outer shell 3. In the following description, parts of the inner bag 4 that correspond to the mouth 5, body 6, and bottom 7 of the container body 2 will be referred to as the mouth 5, body 6, and bottom 7 of the inner bag 4, respectively. It is called. The same applies to the outer shell 3.

The average wall thickness of the outer shell 3 at the center of the body 6 in the height direction is, for example, 200 to 800 μm, and preferably 250 to 500 μm. 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800 μm, and may be within a range between any two of the numerical values exemplified here.

The average wall thickness of the inner bag 4 at the center of the body 6 in the height direction is, for example, 50 to 250 μm, preferably 50 to 100 μm. Specifically, this wall thickness is, for example, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240. , 250 μm, and may be within a range between any two of the numerical values exemplified here or below any one thereof. In this specification, the average wall thickness at a predetermined height position means the average value of the measured values at eight measurement points set at equal intervals in the circumferential direction at that height position.

If the mouth attachment member 8 is not provided with a check valve, the inner bag 4 will not contract even after the contents of the inner bag 4 are discharged, so the inner bag 4 can be pulled out through the mouth 5 of the outer shell 3. It's not easy. Since the present invention makes it easy to pull out the inner bag 4 through the mouth 5 of the outer shell 3, it is significant to apply the present invention when the mouth attachment member 8 is not provided with a check valve. is particularly noticeable.

The inner diameter of the mouth portion 5 of the outer shell 3 is, for example, 20 to 50 mm, preferably 25 to 40 mm. Specifically, the inner diameter of the mouth portion 5 of the outer shell 3 is, for example, 20, 25, 30, 35, 40, 45, 50 mm, and is within the range between any two of the numerical values exemplified here. Good too. The length of the mouth portion 5 is, for example, 15 to 45 mm, specifically, for example, 15, 20, 25, 30, 35, 40, 45 mm, and the range is between any two of the numerical values exemplified here. It may be within.

<Detailed structure of outer shell 3 and inner bag 4>
As shown in FIGS. 3 and 4, the inner bag 4 includes a protrusion 4c that protrudes from the open end 3a of the outer shell 3. As shown in FIGS. The protruding portion 4c includes a protruding tube 4c1, an engaging convex portion 4c2, an annular convex portion 4c5, and an abutting flange 4c4.

The annular convex portion 4c5 engages with the mouth mounting member 8 in the axial direction. The engagement convex portion 4c2 engages with the mouth mounting member 8 in the circumferential direction. In this specification, the "axial direction" is the direction in which the central axis C of the mouth portion 5 extends, or in other words, the direction in which the inner bag 4 is pulled out from the container body 2. The “circumferential direction” is a direction in which the mouth portion 5 is rotated about the central axis C, or in other words, a direction in which the inner bag 4 is rotated in the mouth portion 5 with respect to the outer shell 3.

It is preferable that the engagement convex portions 4c2 are provided at a plurality of locations (eight locations in this embodiment) spaced apart in the circumferential direction. The engagement convex portion 4c2 is arranged on the annular convex portion 4c5, and is provided so as to protrude radially outward from the annular convex portion 4c5. The annular convex portion 4c5 and the engagement convex portion 4c2 are provided with tapered surfaces 4c8 and 4c3 on their upper surfaces. This allows the annular protrusion 28c (shown in FIG. 7A) of the mouth attachment member 8 to easily climb over the annular protrusion 4c5 and the engagement protrusion 4c2, as will be described later.

Further, as shown in FIG. 7A, the lower surface 4c6 of the engagement projection 4c2 is flush with the lower surface 4c7 of the annular projection 4c5, or is closer to the opening end of the inner bag 4 than the lower surface 4c7 of the annular projection 4c5. located at the location. According to such a configuration, the engagement between the annular protrusion 4c5 and the mouth attachment member 8 in the axial direction is reinforced by the engagement protrusion 4c2, so that the engagement between the mouth attachment member 8 and the inner bag 4 is strengthened. becomes strong.

The abutting flange 4c4 is an annular portion disposed at a position abutting the open end 3a and having a diameter larger than that of the protruding tube 4c1. By abutting the abutting flange 4c4 against the open end 3a, the inner bag 4 is prevented from falling into the outer shell 3.

As shown in FIG. 4, a cam protrusion 4g and an engagement protrusion 4h are provided on the outer peripheral surface of the inner bag main body 4d. The engagement protrusion 4h is provided on the cam protrusion 4g. The lower surfaces of the cam convex portion 4g and the engagement convex portion 4h are respectively inclined so as to approach the open end 5c as they proceed counterclockwise when viewed from the open end 5c side of the mouth portion 5.

As shown in FIG. 5, the inner peripheral surface of the outer shell 3 is provided with a cam rail 3l, an engagement recess 3m, and an engagement protrusion 3n. The engagement recess 3m is provided such that the lower surface of the engagement recess 3m is continuous with the upper surface of the cam rail 3l. The upper surface of the cam rail 3l and the lower surface of the engagement recess 3m are inclined so as to approach the opening end 3a as they proceed counterclockwise when viewed from the opening end 3a side. The engagement convex portion 3n is arranged at a position adjacent to the engagement recess 3m.

Before the inner bag 4 is pulled out from the container body 2, the engagement protrusion 4h is disposed within the engagement recess 3m, and the lower surface of the cam protrusion 4g is in contact with the upper surface of the cam rail 3l. A cam mechanism 31 is constituted by the cam convex portion 4g and the cam rail 3l. In this embodiment, the engagement recess 3m is a through hole, but may be a non-through hole.

When an attempt is made to rotate the inner bag 4 counterclockwise, the engagement protrusion 4h comes into contact with the engagement protrusion 3n, and the rotation is restricted. This regulation is not strong, and if a strong torque (torque greater than inner stopper rotation torque T2 described later) is applied to the inner bag 4, the engagement protrusion 4h will overcome the engagement protrusion 3n, and the inner bag 4 will be attached to the outer shell. It can be rotated freely relative to 3. Then, when the inner bag 4 is further rotated counterclockwise, the inner bag 4 moves in the direction of coming out of the container body 2 by the action of the cam mechanism 31. At this time, the inner bag 4 is twisted to reduce its diameter.

An enlarged diameter structure 4k is provided at the open end 4l of the inner bag 4. The expanded diameter structure 4k increases the rigidity of the opening 5 of the inner bag 4 and suppresses deformation of the opening 5 of the inner bag 4. In this embodiment, since the inner bag 4 is pulled out using the engaging portion 4m (more specifically, the annular convex portion 4c5 and the engaging convex portion 4c2) provided on the inner bag 4, a high load is applied to the inner bag 4. In that case, if the open end 4l of the inner bag 4 is easily deformed, it may become difficult to pull out the inner bag 4, but in this embodiment, the deformation of the open end 4l of the inner bag 4 is suppressed. Therefore, the inner bag 4 can be pulled out smoothly.

<Removal of inner bag 4 by simple operation>
The spout attachment member 8 is a stopper type and is configured to be attachable to the mouth portion 5 of the container body 2. With the spout attachment member 8 placed over the mouth portion 5, the spout attachment member 8 is attached to the bottom portion 7. By pressing in the direction of , the mouth attachment member 8 can be engaged with and attached to the mouth 5 . Since the capper-type mouth attachment member 8 can be attached simply by pressing, it has the advantage that the process of attaching the mouth attachment member 8 in the content filling line can be simplified.

By the way, a capper-type mouth attachment member generally includes a sorting band that is separable from the inner stopper, and by engaging the engaging part of the sorting band with the engaging part of the outer shell, it can be attached to the container body. configured to be installed. When removing the mouth attachment member from the mouth, the engaging force between the mouth attachment member and the outer shell is weakened by first tearing off the connection between the inner stopper and the separation band and removing the separation band. (usually to release the engagement), followed by an operation to remove the mouth attachment member from the mouth. However, it is cumbersome to perform an operation to weaken the engagement force between the mouth mounting member and the outer shell before removing the mouth mounting member from the mouth. The operation of weakening the engagement force may be, for example, an operation of weakening the engagement force between the separation band and the outer shell by making a notch in the separation band without removing the separation band.

In this embodiment, in order to solve this problem, the inner bag 4 moves in the direction of coming out of the container body 2 by rotating the mouth attachment member 8 with respect to the outer shell 3 (that is, the inner bag 4 In addition, the spout can be lifted up without performing an operation to weaken the engagement force between the spout mounting member 8 and the outer shell 3 before rotating the spout mounting member 8 relative to the container body 2. This allows the mounting member 8 to be rotated relative to the outer shell 3. In other words, the spout mounting member 8 can be rotated while the spout mounting member 8 remains engaged with the outer shell 3 at the time the spout mounting member 8 is attached to the spout 5 of the container body 2. It has become.

More specifically, the mouth attachment member 8 is plugged and engaged with the mouth 5 of the inner bag 4 in the circumferential direction and the axial direction, and as the mouth attachment member 8 rotates, the inner bag 4 is configured to rotate relative to the outer shell 3. By the action of the cam mechanism 31 provided between the inner bag 4 and the outer shell 3, the inner bag 4 is configured to move in the direction of coming out of the container body 2 as the inner bag 4 rotates.

According to such a configuration, the inner bag 4 can be moved in the direction of coming out of the container body 2 simply by rotating the mouth attachment member 8 without performing a troublesome operation such as removing the sorting band in advance. After that, the inner bag 4 can be pulled out from the container body 2 by pulling the mouth attachment member 8. In other words, the inner bag 4 can be pulled out simply by turning and pulling the mouth attachment member 8, so the operation required to pull out the inner bag 4 becomes very simple. The rotation of the mouth attachment member 8 at this time is preferably in the normal screw loosening direction (that is, in the counterclockwise direction when viewed from the top of the double container 1). In this case, there is an advantage that it is easy to intuitively understand that the inner bag 4 moves in the direction in which it comes out of the container body 2.

Further, since the body 6 of the container body 2 has a larger outer diameter than the mouth 5, it is not easy to pull out the inner bag 4 through the mouth 5 of the outer shell 3 by simply pulling the inner bag 4. However, by rotating the opening 5 of the inner bag 4 and twisting the inner bag 4 to reduce the diameter of the trunk 6 of the inner bag 4, the trunk 6 of the inner bag 4 passes through the opening 5 of the outer shell 3. The inner bag 4 can be easily pulled out from the container body 2.

<Detailed structure of mouth attachment member 8>
As shown in FIG. 2, in this embodiment, the mouth attachment member 8 is a cap 8a, and includes an inner stopper 26 and an overcap 27. The inner plug 26 is of a stopper type and is engaged with the mouth portion 5 of the inner bag 4 in the circumferential direction and the axial direction. The overcap 27 is screwed onto the inner stopper 26.

As shown in FIGS. 2, 6, and 8, the overcap 27 includes an outer cylinder 27a, an intermediate cylinder 27b, an inner cylinder 27c, and a top plate 27d.

A knurl 27e is provided on the outer peripheral surface of the outer cylinder 27a, making it easier to grip and rotate the overcap 27. A female threaded portion 27f is provided on the inner peripheral surface of the outer cylinder 27a. The top plate 27d is provided on the upper surface of the outer tube 27a. An intermediate cylinder 27b and an inner cylinder 27c are provided on the lower surface of the top plate 27d. The intermediate cylinder 27b is a so-called inner ring that has a smaller diameter than the outer cylinder 27a and is arranged inside the outer cylinder 27a. The inner cylinder 27c has a smaller diameter than the intermediate cylinder 27b, and is arranged inside the intermediate cylinder 27b.

As shown in FIGS. 2 and 6 to 8, the inner plug 26 includes a main body portion 28 and a plug opening portion 32. As shown in FIG. The main body portion 28 and the opening portion 32 are connected to each other via an easily tearable connecting portion 30.

The main body portion 28 includes an outer cylinder 28a, an inner cylinder 28b, an annular projection 28c, an engaging projection 28d, a top plate 28e, a discharge cylinder 28f, and a mounting cylinder 28g. The opening part 32 and the connecting part 30 are arranged inside the discharge cylinder 28f and the inner cylinder 28b. The opening part 32 is provided with an engagement cylinder 32a provided with an engagement part (not shown), and the inner cylinder 27c and the engagement cylinder 32a are engaged in the circumferential direction and the axial direction. According to such a configuration, by rotating the overcap 27 with respect to the main body part 28, it becomes possible to rotate the engagement tube 32a with respect to the main body part and break the connecting part 30. By breaking the connecting part 30, the opening part 32 is separated from the main body part 28, and a communication hole is formed inside the discharge cylinder 28f and the inner cylinder 28b. The contents in the inner bag 4 can be discharged through this flow hole.

A knurl 28i is provided on the outer peripheral surface of the outer cylinder 27a, making it easier to grip and rotate the inner stopper 26. The top plate 28e is provided on the upper surface of the outer cylinder 28a. An inner cylinder 28b is provided on the lower surface of the top plate 28e. The inner cylinder 28b is a so-called inner ring that has a smaller diameter than the outer cylinder 28a and is arranged inside the outer cylinder 28a. When the inner plug 26 is attached to the mouth portion 5, the inner tube 28b is inserted into the inner bag 4, and the outer circumferential surface of the inner tube 28b comes into close contact with the inner circumferential surface of the inner bag 4.

A discharge cylinder 28f and a mounting cylinder 28g are provided on the upper surface of the top plate 28e. The contents in the inner bag 4 are discharged through the discharge tube 28f. As shown in FIG. 2, a male threaded portion 28h is provided on the outer circumferential surface of the mounting tube 28g, and a female threaded portion 28h is provided on the inner circumferential surface of the outer tube 27a of the overcap 27. By engaging with 27f, the overcap 27 is screwed onto the inner stopper 26. In this case, the overcap 27 can be attached to and removed from the inner plug 26 by rotating the overcap 27 relative to the inner plug 26. When the overcap 27 is attached to the inner stopper 26, the intermediate cylinder 27b is inserted into the discharge cylinder 28f, and the outer peripheral surface of the intermediate cylinder 27b is brought into close contact with the inner peripheral surface of the discharge cylinder 28f. The upper side of the discharge cylinder 28f is closed by the overcap 27.

The annular convex portion 28c is an annular convex portion provided on the inner circumferential surface of the outer cylinder 28a so as to extend in the circumferential direction. When the annular convex portion 28c engages with the engagement convex portion 4c2 in the axial direction, the main body portion 28 engages with the mouth portion 5 of the inner bag 4 in the axial direction. It is preferable that the engagement convex portions 28d are provided at a plurality of locations (eight locations in this embodiment) spaced apart in the circumferential direction. The engagement convex portion 28d is disposed on the annular convex portion 28c, and is provided so as to protrude radially inward from the annular convex portion 28c. The engaging convex portion 28d is arranged between the adjacent engaging convex portions 4c2, so that the main body portion 28 engages with the mouth portion 5 of the inner bag 4 in the circumferential direction.

<Rotation direction and torque of overcap 27 and inner plug 26>
The overcap 27 is preferably screwed onto the inner stopper 26 with a normal thread. Therefore, by rotating the overcap 27 with respect to the inner plug 26 in the normal screw loosening direction, the overcap 27 and the inner plug 26 can be unscrewed from each other. Further, by rotating the inner plug 26 with respect to the outer shell 3 in the normal screw loosening direction, the inner bag 4 is configured to move in the direction of coming out of the container body 2. In this way, the overcap 27 can be removed by rotating the overcap 27 in the direction of loosening the normal screws, and the inner bag 4 can be lifted up by rotating the inner plug 26 in the direction of loosening the normal screws. . Since both operations are performed in the same direction of rotation, they have the advantage of being simple to operate.

On the other hand, in the case of the above configuration, when the container body 2 and the overcap 27 are gripped and the overcap 27 is rotated in the direction of loosening the normal screw, the overcap 27 does not rotate relative to the inner stopper 26 and the overcap 27 Both the inner plug 26 and the inner plug 26 rotate relative to the container body 2, and as a result, there is a possibility that the inner bag 4 may float up.

In order to suppress the occurrence of such a problem, in this embodiment, the overcap rotation torque required to rotate the overcap 27 in the normal screw loosening direction for the first time with respect to the inner stopper 26 is set as T1, and the overcap rotation torque is set as T1, and On the other hand, if the inner plug rotation torque required to rotate the inner plug 26 in the positive screw loosening direction for the first time is T2, T2/T1 is preferably 1.2 or more. By applying a torque equal to or greater than the overcap rotation torque T1 to the overcap 27, the overcap 27 can be rotated in the loosening direction. By applying a torque greater than or equal to the inner plug rotation torque T2 to the inner plug 26, the inner plug 26 can be rotated in the loosening direction.

In this case, when the container body 2 and the overcap 27 are grasped and the overcap 27 is rotated in the direction of loosening the normal screw, the overcap 27 is attached to the inner stopper 26 before the inner stopper 26 rotates with respect to the outer shell 3. Since it rotates against the other hand, the occurrence of the above-mentioned problem is suppressed. T2/T1 is, for example, 1.2 to 5, preferably 1.5 to 3. Specifically, T2/T1 is, for example, 1.2, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, and here It may be within the range between any two of the numerical values exemplified.

T1 is, for example, 40 to 120 N·cm, preferably 60 to 100 N·cm. T2 is, for example, 100 to 200 N·cm, preferably 130 to 170 N·cm. Specifically, T1 is, for example, 40, 50, 60, 70, 80, 90, 100, 110, 120 N cm, and is within a range between any two of the numerical values exemplified here, or more than or equal to any two of the numerical values exemplified here. It may be the following. Specifically, T2 is, for example, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200 N cm, and is within a range between any two of the numerical values exemplified here or It may be more or less than any one.

In this embodiment, the overcap rotation torque T1 is the torque required to break the connecting portion 30 and separate the opening portion 32 from the main body portion 28. In another embodiment, instead of providing the opening part 32 on the inner stopper 26, the overcap 27 is provided with an opening ring via an easily tearable connection part, and the opening ring engages the inner stopper 26 in the circumferential direction. do. In such a configuration, the torque required to break the thin wall portion and separate the opening ring from the overcap 27 is the overcap rotation torque T1. Furthermore, in another embodiment, a rotation restriction structure is provided that restricts the rotation of the overcap 27 with respect to the inner plug 26, and when the rotation restriction by the rotation restriction structure is released by a predetermined torque (for example, the overcap 27 When the convex part of the overcap 27 comes into contact with the convex part of the inner plug 26, the rotation is restricted, and the convex part of the overcap 27 climbs over the convex part of the inner plug 26, so that the rotation is unrestricted), the restriction is released. The torque required for this is the overcap rotation torque T1.

In this embodiment, the inner plug rotation torque T2 is the torque required for the engagement protrusion 4h to overcome the engagement protrusion 3n. In another embodiment, for example, the inner plug 26 and the outer shell 3 may be engaged in the circumferential direction, and the engagement may be released when the inner plug rotation torque T2 is applied.

Further, if T3 is the overturn torque required to rotate the inner stopper 26 in the positive screw loosening direction for the first time with respect to the inner bag 4, T3/T2 is preferably 1.2 or more. This prevents the inner plug 26 from rotating idly relative to the inner bag 4. T3/T2 is, for example, 1.2 to 5, preferably 1.5 to 3. Specifically, T3/T2 is, for example, 1.2, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, and here It may be within the range between any two of the numerical values exemplified above or more than any one.

T3 is, for example, 200 N·cm or more, preferably 200 to 1000 N·cm, and specifically, for example, 200, 250, 300, 350, 400, 500, 1000 N·cm, and any of the numerical values exemplified here. or within a range between the two. In this embodiment, the overturn torque T3 is the torque necessary for the engagement protrusion 28d to overcome the engagement protrusion 4c2.

<Preventing erroneous operations using shrink film>
By the way, there is a possibility that the user intends to grip and rotate the overcap 27, but accidentally grips and rotates the inner stopper 26. In this case, as the inner plug 26 rotates, the inner bag 4 may be twisted and the contents may overflow.

In this embodiment, as shown in FIG. 9, a shrink film 33 is used to suppress the occurrence of such problems. In this embodiment, the shrink film 33 covers the container body 2, the inner stopper 26, and the overcap 27 before opening. The shrink film 33 is provided with easy cutting lines 33a and 33b. The easy-to-cut lines 33a and 33b are lines that facilitate cutting of the shrink film, such as perforations and half-cut lines. The easy-to-cut line 33a is provided so as to extend in the circumferential direction of the inner plug 26 at the boundary between the inner plug 26 and the overcap 27 or at a position facing the inner plug 26. When a part of the shrink film 33 (that is, the upper part 33c above the easy cut line 33a) is removed along the easy cut line 33a, the shrink film 33 covers the inner stopper 26 and the overcap 27 is removed. It will be in a covered state without being covered. In this state, it is difficult to grasp and rotate the inner stopper 26, so that erroneous operations such as accidentally rotating the inner stopper 26 can be suppressed. Note that instead of providing the easy-to-cut line 33a, the shrink film 33 is attached so that the upper edge of the shrink film 33 is located at the boundary between the inner plug 26 and the overcap 27 or at a position facing the inner plug 26. You can. In this case, before a part of the shrink film 33 is removed, a covering state is achieved in which the inner stopper 26 is covered but the overcap 27 is not covered.

Further, the easy-to-cut line 33b is provided to facilitate removal of the lower portion 33d of the shrink film 33 below the easy-to-cut line 33a. It is preferable that the easy-to-cut line 33b is provided non-parallel to the easy-to-cut line 33a and perpendicular to the easy-to-cut line 33a. Moreover, it is preferable that the easy-to-cut line 33b is connected to the easy-to-cut line 33a, and preferably reaches the lower edge of the lower part 33d.

Note that the prevention of erroneous operation using the shrink film is also applicable when the cap 8a is not a plugging type. When the cap 8a is of a screw type, the cap 8a is attached to the container body 2 by screwing the cap 8a onto the opening of the outer shell 3. In addition, the prevention of erroneous operation using a shrink film can also be applied when the overcap is engaged with the inner stopper 26 by, for example, snap engagement rather than screw engagement. Furthermore, it is also applicable to a configuration in which the inner bag 4 is lifted up by rotating the inner plug 26 in the reverse screw loosening direction.

<Shape of container body 2>
In this embodiment, as shown in FIGS. 2 and 10 to 12, the shape of the body 6 of the container body 2 becomes approximately square in cross section (square with rounded corners) as it approaches the bottom 7. ing. More specifically, the upper end of the shoulder portion 6b has a circular cross section as shown in FIG. 12A, and the torso main body 6c has a substantially square cross section as shown in FIG. 12C. As shown in FIG. 2B, in the middle of the shoulder portion 6b, the cross section has a shape between a circle and a substantially square shape. That is, at the shoulder portion 6b, the diameter of the container body 2 is expanded toward the bottom portion 7, and the shape gradually approaches a substantially rectangular cross-sectional shape. Further, the bottom portion 7 is provided with a recessed portion 7a.

FIG. 12C shows a cross section P at a position 0.2J from the bottom of the container body 2, where J is the total height of the container body 2. In the cross section P, the container main body 2 has three or more corners 2a provided at intervals in the circumferential direction, and the radius of curvature between the corners 2a is smaller than that of the corners 2a. A large connecting portion 2b is provided. The inner bag 4 also has the same shape as the container body 2. The radius of curvature means the value at the outer surface of the container body 2, unless otherwise stated.

In the container main body 2 having such a shape, when the inner bag 4 is rotated counterclockwise with respect to the outer shell 3, the connecting portion 2b is more easily rotated than the corner portion 2a, so as shown in FIG. A bent shape 2c is likely to be formed near the boundary between the connecting portion 2b and the corner portion 2a. When the inner bag 4 is further rotated counterclockwise in this state, the diameter of the inner bag 4 is reduced so that the corner 2a of the inner bag 4 is folded, making it easier to pull out the inner bag 4. In this embodiment, the number of corner portions 2a is four, but the same effects can be achieved even when the number of corner portions 2a is three or five or more. The number of corner portions 2a is, for example, 3 to 12, preferably 3 to 6.

In cross section P, if the length of the longest among the connecting parts 2b is L1, and the length of the shortest among the connecting parts 2b is L2, then the value of [(L1-L2)/L1] is 0.1 or less It is preferable that In this case, the lengths of all the connecting portions 2b are approximately the same, and the cross sections thereof are approximately regular polygonal. In this case, since the connecting portion 2b is more easily rotated, the corner portion 2a of the inner bag 4 is more easily folded.

In cross section P, if the radius of curvature at the corner portion 2a is the minimum radius is R1, and the radius of curvature at the connecting portion 2b is the maximum radius is R2, then R2/R1 is 3. It is preferable that it is above. In this case, the corner portion 2a of the inner bag 4 is more easily folded. The connecting portion 2b may be a flat surface, in which case the radius of curvature becomes infinite. It is preferable that the corner portion 2a is convex toward the outside of the container body 2. The connecting portion 2b may be outwardly convex, flat, or inwardly convex. R2/R1 is, for example, 3 to 1000, specifically, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 , 19, 20, 100, 500, and 1000, and may be within a range between any two of the numerical values exemplified here or more than any one.

The radius of curvature R1 is, for example, 5 to 20 mm, and specifically, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 mm. and may be within the range between any two of the numerical values exemplified here. The radius of curvature R2 is, for example, 30 mm or more, preferably 30 to 200 mm, and specifically, for example, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, They are 160, 170, 180, 190, and 200 mm, and may be within a range between any two of the numerical values exemplified here or more than any one. When the equivalent circle radius of the container body 2 at the cross section P is R3, R1/R3 is, for example, 0.2 to 0.6, and specifically, for example, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, and may be within the range between any two of the numerical values exemplified here. The equivalent circle radius R3 is, for example, 15 to 40 mm, and specifically, for example, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 mm, and may be within a range between any two of the numerical values exemplified here.

In cross section P, the wall thickness of the inner bag 4 at the corner 2a where the wall thickness is the minimum is T1, and the wall thickness at the joint portion 2b where the wall thickness of the inner bag 4 is the maximum is T2. Then, T1/T2 is preferably 0.90 or less. In cross section P, if the average value of the wall thickness of the inner bag 4 at all corners 2a is T1a, and the average value of the wall thickness of the inner bag 4 at all connecting parts 2b is T2a, then T1a/T2a is: It is preferably 0.90 or less. In this case, the corner portion 2a of the inner bag 4 is more easily folded. T1/T2 or T1a/T2a is, for example, 0.40 to 0.90, and specifically, for example, 0.40, 0.45, 0.50, 0.55, 0.60, 0 .65, 0.70, 0.75, 0.80, 0.85, 0.90, and may be within the range between any two of the numerical values exemplified here. T1 and T1a are each preferably 95 μm or less. T1 and T1a are each, for example, 50 to 95 μm, specifically, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 μm, and any of the numerical values exemplified here. It may be within the range between or below. T2 and T2a are each, for example, 60 to 150 μm, specifically, for example, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150 μm, and any of the numerical values exemplified here. or within a range between the two.

<Method for discharging the contents in the double container 1>
As described above, in the double container 1 of this embodiment, the inner bag 4 can be pulled out from the container body 2 using the mouth attachment member 8. As shown in FIG. 14, the mouth attachment member 8 remains engaged with the inner bag 4 after being pulled out.

When the mouth attachment member 8 is a cap 8a, the inner bag 4 is pulled out from the container main body 2 with some of the contents remaining in the inner bag 4 (pulling process), and then the contents remaining in the inner bag 4 are removed. The contents contained in the container can be discharged (discharge step).

The inner bag 4 has higher flexibility than the outer shell 3, so by squeezing or compressing the inner bag 4, it is easy to discharge the contents, and when further discharge becomes impossible, the remaining amount (hereinafter referred to as "Final residual amount") can be reduced.

Generally, the final residual amount tends to increase as the viscosity increases, but according to the method of this embodiment, even when the viscosity is high, an increase in the final residual amount can be suppressed. Therefore, the method of the present embodiment has remarkable technical significance when the content has a high viscosity (for example, 100 mPa·sec or more. The viscosity of the content is, for example, 100 to 10,000 mPa·sec, and the specific For example, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000mPa・sec. It may be within a range between any two numerical values or more than any one.

By the way, as shown in FIG. 10, the bottom 7 of the container body 2 is provided with a truncated cone-shaped recess 7a. The recess 7a is also provided in the bottom 7 of the inner bag 4. Since the truncated conical recess 7a has a circular cross section (cross section perpendicular to the central axis C), it is difficult to deform.If the truncated conical recess 7a exists in the inner bag 4, the final residual amount There is a risk that the reduction will not be sufficient. From this point of view, it is preferable to provide the bottom of the container body 2 with a recessed portion having a flat cross section. Since such a recess is easier to deform than a recess with a circular cross section, the final residual amount can be further reduced.

Furthermore, if the engagement force between the inner bag 4 and the cap 8a is weak, there is a risk that the cap 8a will come off from the inner bag 4 after the inner bag 4 is pulled out, and the contents may leak out from the inner bag 4. On the other hand, in this embodiment, the engagement in the axial direction between the annular protrusion 4c5 and the mouth attachment member 8 is reinforced by the engagement protrusion 4c2, so that the engagement between the cap 8a and the inner bag 4 is strong. This prevents the cap 8a from coming off from the inner bag 4.

<Thickness of inner bag 4>
It is preferable that the inner bag 4 has a small wall thickness. This is because the smaller the wall thickness of the inner bag 4, the more flexible the inner bag 4 becomes, making it easier to reduce the final residual amount and making it possible to reduce the amount of resin used.

From this point of view, it is preferable that the inner bag 4 includes a thin portion having a wall thickness of 100 μm or less. Further, it is preferable that the thin portion be provided at a position closer to the bottom than the center of the body 6 in the height direction. The thickness of the thin portion is preferably 95 μm or less, more preferably 90 μm or less, for example, 50 to 100 μm, specifically, for example, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95 , 100 μm, and may be within a range between any two of the numerical values exemplified here.

<Layer composition of inner bag 4>
The inner bag 4 may have a single layer structure or a multilayer structure. As shown in FIG. 15, the inner bag 4 preferably includes, in order from the inside of the inner bag 4, an inner layer 4i, a gas barrier layer 4j, and an outer layer 4e.

The inner layer 4i is a layer disposed inside the inner bag 4 than the gas barrier layer 4j. By providing the inner bag 4 with the inner layer 4i, exposure of the gas barrier layer 4j to moisture contained in the contents is suppressed.

The thickness of the inner layer 4i is, for example, 5 to 60 μm, specifically, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 μm, where It may be within the range between any two of the illustrated numerical values. The inner layer 4i preferably includes, in order from the inside of the inner bag 4, an innermost layer 4i1, a repro layer 4i2, and an adhesive layer 4i3.

The innermost layer 4i1 is preferably made of a resin with excellent moisture barrier properties such as polyolefin (eg, polyethylene, polypropylene) or PET. The innermost layer 4i1 is a layer that comes into contact with the contents in the inner bag 4, and is preferably made of new resin (hereinafter referred to as "virgin resin") rather than recycled resin in order to suppress contamination of the contents.

The repro layer 4i2 is preferably made of a resin containing a recycled resin, and is preferably made of a mixed resin made of a recycled resin and a virgin resin. By providing the repro layer 4i2, environmental load and container manufacturing costs can be reduced. The repro layer 4i2 can be omitted if unnecessary.

Assuming that the entire mixed resin is 100% by mass, the mixed resin contains 15 to 50% by mass of recycled resin (15, 20, 25, 30, 35, 40, 45, 50% by mass) and 50 to 85% by mass of virgin resin. (50, 55, 60, 65, 70, 75, 80, 85% by mass). The proportion of recycled resin and virgin resin may be within a range between any two of the numerical values exemplified in parentheses. The recycled resin is a resin obtained by recycling scraps generated during molding of the container body 2. Since the scrap includes all the layers of the container body 2, the recycled resin is a mixture of resin compositions constituting each of all the layers of the container body 2.

The adhesive layer 4i3 is made of adhesive resin. Examples of adhesive resins include acid-modified polyolefin resins (eg, maleic anhydride-modified polyethylene, maleic anhydride-modified polypropylene), and the like. By providing the adhesive layer 4i3, the adhesion between layers adjacent to the adhesive layer 4i3 is improved.

The outer layer 4e is a layer disposed on the outer side of the inner bag 4 than the gas barrier layer 4j. By providing the inner bag 4 with the outer layer 4e, exposure of the gas barrier layer 4j to moisture contained in the outside air is suppressed.

The thickness of the outer layer 4e is, for example, 5 to 60 μm, specifically, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 μm, where It may be within the range between any two of the illustrated numerical values. The outer layer 4e preferably includes, in order from the outside of the inner bag 4, an outermost layer 4e1 and an adhesive layer 4e2.

The outermost layer 4e1 is preferably made of a resin with excellent moisture barrier properties such as polyolefin (eg, polyethylene, polypropylene) or PET. The outermost layer 4e1 is a layer exposed to the outside of the inner bag 4, and is preferably made of virgin resin in order to suppress contamination of the external environment.

The description of the adhesive layer 4e2 is the same as that of the adhesive layer 4i3.

The value of (thickness of inner layer 4i/thickness of outer layer 4e) is preferably from 0.2 to 5, for example. Specifically, this value is, for example, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2. 4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.5, 4.0, 4.5, 5.0, and the numerical values exemplified here. It may be within the range between any two.

When the inner layer 4i is thicker than the outer layer 4e, the gas barrier layer 4j can be more reliably protected from moisture in the contents. When the outer layer 4e is thicker than the inner layer 4i, the gas barrier layer 4j can be more reliably protected from external moisture.

In this embodiment, by making the inner layer 4i thicker than the outer layer 4e and arranging the repro layer 4i2 on the inner layer 4i, it is possible to make the repro layer 4i2 relatively thick. However, the repro layer 4i2 may be provided on both the inner layer 4i and the outer layer 4e, or may be provided only on the outer layer 4e. Further, the repro layer 4i2 may include a material such as a post-consumer material that may contain a strong odor or component transfer to the contents, and in this case, the repro layer 4i2 may transfer odor or components to the contents. In order to suppress component migration, the repro layer 4i2 is preferably disposed on the outer layer 4e. In this case, the outer layer 4e may be made thicker than the inner layer 4i to increase the amount of resin used in the repro layer 4i2.

The gas barrier layer 4j is made of gas barrier resin. In this specification, the gas barrier resin is a resin whose oxygen permeability is less than 50 cc/(m ² , 24 hours, atm) in an environment of 20° C. and 65% RH when formed into a 20 μm thick film. means. The oxygen permeability is, for example, 0 to 49 cc/(m ² /24 hours/atm), and specifically, for example, 0.01, 0.1, 0.2, 0.5, 1, 2, 5 , 10, 15, 20, 25, 30, 35, 40, 45, 49cc/( ^m2・24 hours・atm), and within the range between any two of the numerical values exemplified here or below any one. There may be.

The gas barrier resin preferably has a value of (oxygen permeability in an environment of 20°C and 100% RH)/(oxygen permeability in an environment of 20°C and 40% RH) of 2 or more, and 5. The above is more preferable. The larger this value is, the lower the gas barrier property is at high humidity, and the technical significance of applying the present invention is significant. This value is, for example, 2 to 10,000, specifically, for example, 2, 5, 10, 20, 50, 100, 200, 1,000, 10,000, and ranges between any two of the numerical values exemplified here. It may be within or above.

The gas barrier resin may be composed only of a resin with high gas barrier properties such as EVOH or polyamide, or may be a mixed resin of the above resin and another resin. Other resins include adhesive resins. By blending adhesive resin into the gas barrier layer 4j, the adhesive layers 4i3 and 4e2 can be omitted, and the number of layers constituting the inner bag 4 can be reduced.

The thickness of the gas barrier layer 4j is, for example, 20 to 100 μm, specifically, for example, 20, 30, 40, 50, 60, 70, 80, 90, 100 μm, and may be any of the values exemplified here. It may be within a range between the two.

1-2. Method for Manufacturing Double Container 1 As shown in FIGS. 16 to 18, the container body 2 can be formed by heating a preform 15 and performing biaxial stretch blow molding.

<Configuration of inner preform 14, outer preform 13, and preform 15>
In one example, the preform 15 can be configured by covering an inner preform 14, which will become the inner bag 4, with an outer preform 13, which will become the outer shell 3.

As shown in FIG. 16, the inner preform 14 has a bottomed cylindrical shape and includes a mouth portion 14a, a body portion 14b, and a bottom portion 14c. A protrusion 14d is provided at the open end of the mouth 14a. The protruding part 14d does not deform during molding and becomes the protruding part 4c in its original shape. Therefore, the matters described regarding the protrusion 4c also apply to the protrusion 14d. The protruding portion 14d is provided with an engaging portion 14m. The engaging portion 14m becomes an engaging portion 4m after molding, and is used for pulling out the inner bag 4. The bottom portion 14c is provided to close the lower end of the body portion 14b. A positioning pin (not shown) may be provided on the bottom portion 14c.

As shown in FIG. 16, the outer preform 13 has a bottomed cylindrical shape and includes a mouth portion 13a, a body portion 13b, and a bottom portion 13c. The bottom portion 13c is provided to close the lower end of the body portion 13b. The bottom portion 13c is provided with an annular convex portion 13d and a positioning hole (not shown).

As shown in FIG. 18, a preform 15 can be formed by covering the inner preform 14 with the outer preform 13. If the inner preform 14 is provided with a positioning pin, the positioning pin can be inserted into the positioning hole of the outer preform 13 to position the inner preform 14 and the outer preform 13 relative to each other. In the preform 15, the opening 14a and the opening 13a face each other, and the body 14b and the body 13b face each other.

The mouth parts 13a and 14a become the mouth part 15a of the preform 15, the body parts 13b and 14b become the body part 15b of the preform 15, and the bottom parts 13c and 14c become the bottom part 15c of the preform 15. The body portion 15b and the bottom portion 15c are mainly stretched in biaxial stretch blow molding.

<Materials and manufacturing method of inner preform 14 and outer preform 13>
The inner preform 14 and the outer preform 13 can be formed by direct blow molding, injection molding, or the like of a thermoplastic resin such as polyester (eg, PET) or polyolefin (eg, polypropylene, polyethylene). In one example, the inner preform 14 is made of polyolefin (eg polypropylene) and the outer preform 13 is made of PET. The polyolefin used for the inner preform 14 is preferably polypropylene rather than polyethylene. This is because the temperature suitable for biaxial stretch blow molding of polypropylene is closer to that of PET than that of polyethylene.

<Manufacture of inner preform 14 by direct blow molding>
The inner preform 14 is preferably formed by direct blow molding using a molten cylindrical parison. In direct blow molding, it is easier to make the inner bag 4 thinner than in injection molding, so by forming the inner preform 14 by direct blow molding, it is possible to make the inner bag 4 thinner. Further, in order to form the inner bag 4 having a multilayer structure, the inner preform 14 may be configured to include, in order from the inside, an inner layer 14i, a gas barrier layer 14j, and an outer layer 14e, as shown in FIG. Although it is desirable, the inner preform 14 having such a configuration is not easy to form by multilayer injection molding, and in addition, for example, if a gate is provided on the bottom part 14c of the inner preform 14, the gas barrier layer 14j is not easily formed. There is a possibility that the resin may not reach the open end of the inner preform 14 and the gas barrier properties may deteriorate. In particular, the smaller the thickness of the inner preform 14, the more difficult it becomes for the resin to flow, and the above problem becomes more pronounced. On the other hand, in direct blow molding, molding is performed using a cylindrical parison having structures corresponding to the inner layer 14i, the gas barrier layer 14j, and the outer layer 14e. Easy to install.

In direct blow molding, a molten cylindrical parison 34 is placed between split molds 35 and 36 in an open state as shown in FIG. 19, and then the split molds 35 and 36 are closed as shown in FIG. This can be done by turning the cylindrical parison 34 into a bag-like parison, blowing air into the bag-like parison, and shaping it into a shape along the shaping surfaces of the split molds 35 and 36. A molded body 38 with burrs 39 is formed by direct blow molding. Thereafter, the molded body 38 is taken out from the split molds 35 and 36 and the burr 39 is removed, thereby obtaining the molded body 38 shown in FIG. 21.

The molded body 38 has a shape in which a bag portion 40 is connected to the open end 14o of the inner preform 14. An annular recess 41 is provided at the boundary between the inner preform 14 and the bag portion 40 to indicate the cutting site.

Next, as shown in FIG. 22, the molded body 38 is cut along the annular recess 41 and the bag portion 40 is removed, thereby obtaining the inner preform 14. The annular recess 41 is a recess on the outside of the molded body 38, but becomes an annular convex portion 41a on the inside of the molded body 38, and when the molded body 38 is cut along the annular recess 41, the annular convex portion 41a If the burr 14p remains partially and protrudes toward the inside of the inner preform 14 as shown in FIG. 22C, or if the annular convex portion 41a is not formed inside the molded body 38, However, burrs 14p may be formed during cutting. If the enlarged diameter structure 14l is not provided at the open end 14o of the inner preform 14, there is a risk that the burr 14p may prevent the outer peripheral surface of the inner cylinder 28b of the inner plug 26 and the inner peripheral surface of the inner bag 4 from coming into close contact with each other. However, in this embodiment, the burr 14p is formed in the enlarged diameter structure 14l, so the burr 14p does not impede the above-mentioned close contact.

<Relationship between the shape of the inner preform 14 and the outer diameter of the cylindrical parison 34>
As shown in FIG. 17B, the outer diameter of the portion of the inner preform 14 having the largest outer diameter at the mouth 14a (the outer diameter at the abutment flange 14n) is set as D1, and as shown in FIG. If the outer diameter of 34 is D3, D1/D3 is preferably 1.5 or more. As D1/D3 becomes larger, the blow ratio when forming the inner preform 14 becomes larger, so the thickness of the mouth portion 14a of the inner preform 14 tends to become smaller. If the wall thickness of the mouth part 14a of the inner preform 14 is small, the rigidity of the mouth part 14a will be small, and when cutting the molded body 38 along the annular recess 41, the mouth part 14a will be deformed, resulting in cutting. It may be difficult to do this accurately. On the other hand, in this embodiment, the opening end 14o of the inner preform 14 is provided with the enlarged diameter structure 14l that suppresses the deformation of the opening 14a, so that the deformation of the opening 14a is suppressed.

D1/D3 is preferably 2 or more, and preferably 2.5 or more. D1/D3 is, for example, 1.5 to 4.0, specifically, for example, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1 , 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3 .4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, and may be within the range between any two of the numerical values exemplified here. D1 is, for example, 25 to 40 mm, specifically, for example, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 mm. , it may be within the range between any two of the numerical values exemplified here. D3 is, for example, 8 to 25 mm, specifically, for example, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 , 25 mm, and may be within a range between any two of the numerical values exemplified here.

The inner preform 14 preferably has a wall thickness of 1.5 mm or less at the open end 14o. In this case, since the rigidity of the opening 14a of the inner preform 14 and the opening 5 of the inner bag 4 is particularly low, the technical significance of providing the enlarged diameter structures 14l and 4k is significant. This wall thickness is, for example, 0.5 to 1.5 mm, specifically, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5 mm, and may be within the range between any two of the numerical values exemplified here.

As shown in FIG. 17B, the total height of the inner preform 14 is H, and the outer diameter of the inner preform 14 at a height position where the height from the bottom 14c of the inner preform 14 is 0.1H is D2. Then, D2/D1 is preferably 0.35 or more, and more preferably 0.50 or more. When the split molds 35 and 36 are closed, the cylindrical parison 34 is pinched between the pinch-off parts 35a and 36a of the split molds 35 and 36, and the inner surfaces of the cylindrical parison 34 are welded together to form a seal. It is formed.

It is not desirable to form the seal portion on the body portion 14b of the inner preform 14 because the seal portion is unsightly. The larger D2 is, the more difficult it is to form a seal portion in the body portion 14b of the inner preform 14, so the outer diameter of the cylindrical parison 34 that can be adopted becomes larger. Moreover, the smaller D1 is, the smaller the blow ratio at the mouth 14a of the inner preform 14 is, and the thicker the mouth 14a is. As a result, the rigidity of the opening 5 of the inner bag 4 increases, making it easier to pull out the inner bag 4.

D2 is, for example, 12 to 30 mm, specifically, for example, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28 , 29, and 30 mm, and may be within a range between any two of the numerical values exemplified here.

Moreover, it is preferable that D2/D1 is 0.8 or less. If D2/D1 is too large, the wall thickness of the body 6 of the inner bag 4 tends to increase, and the discharge properties of the contents may deteriorate.

D2/D1 is, for example, 0.35 to 1.0, specifically, for example, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65. , 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00, and may be within the range between any two of the numerical values exemplified here. .

D2/D3 is preferably 1.1 or more, more preferably 1.4 or more. In this case, a seal portion is less likely to be formed on the body portion 14b of the inner preform 14, and the aesthetic appearance of the inner preform 14 is improved. D2/D3 is, for example, 1.1 to 2.0, specifically, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0, and may be within the range between any two of the numerical values exemplified here.

<Protruding seal portion 42>
The seal portion formed by welding the inner surfaces of the cylindrical parison 34 to each other may have insufficient strength, and as shown in FIG. It is preferable that the protruding seal portion 42 be formed by the protruding seal portion 42. The protruding seal portion 42 is formed by welding the inner surfaces of the cylindrical parison 34 to each other, and protrudes from the main body portion 14q of the inner preform 14. The main body portion 14q refers to a portion of the inner preform 14 other than the protruding seal portion 42. As shown in FIG. 23A, by protruding the seal portion 43 to form the protruding seal portion 42, the area of the seal surface 43a is increased, and the sealing strength of the seal portion 43 is increased.

By the way, when the inner preform 14 includes an inner layer 14i, a gas barrier layer 14j, and an outer layer 14e in order from the inside as shown in FIG. 23A, the opposing inner layers 14i are welded to each other at the sealing surface 43a. However, the gas barrier layers 14j are not welded to each other, and the outer layers 14e are not welded to each other. Therefore, in the vicinity of the seal portion 43, a non-barrier region 44 in which the gas barrier layer 14j is not provided is provided. The wider the non-barrier area 44, the lower the gas barrier properties against the contents.

When such an inner preform 14 is covered with the outer preform 13 and biaxial stretch blow molding is performed, stretching also occurs in the protruding seal portion 42, resulting in a structure as shown in FIG. 23B, and the non-barrier area 44 is wide. As a result, gas barrier properties are further deteriorated. The inner layer 14i, the gas barrier layer 14j, and the outer layer 14e of the main body 14q of the inner preform 14 are the inner layer 4i, the gas barrier layer 4j, and the outer layer 4e of the main body 4q of the inner bag 4, respectively. . Furthermore, in the configurations shown in FIGS. 23A and 23B, since the stretching in the seal portion 43 is not suppressed, force in the direction of peeling off the seal surface 43a is applied from both sides of the seal surface 43a, and there is a possibility that the seal surface 43a may be peeled off. be.

In order to solve this problem, in this embodiment, the protruding seal part 42 as shown in FIG. 24A is formed by direct blow molding, and then the protruding seal part 42 is bent as shown in FIG. 24B to form a bent structure. is formed. For example, the protruding seal portion 42 can be bent after being reheated and softened.

When biaxial stretch blow molding is performed by covering such an inner preform 14 with the outer preform 13, in addition to suppressing stretching at the seal portion 43 by the bent protruding seal portion 42, the seal portion 43 is Even if it is stretched, the non-barrier region 44 does not expand, and the deterioration of gas barrier properties is suppressed. Therefore, in this embodiment, the bent protruding seal portion 42 serves as a stretch suppressing structure that suppresses the seal portion 43 from being stretched during biaxial stretch blow molding.

It is preferable that the main body portion 14q is provided with a groove 14r along the protruding seal portion 42. In this case, by bending and housing the protruding seal part 42 in the groove 14r, the amount of protrusion of the protruding seal part 42 from the main body part 14q is reduced, and even after biaxial stretch blow molding, the protruding seal part 42 remains intact. The corresponding area becomes less noticeable.

It is preferable that the protruding seal portion 42 includes a root portion 42a and an outer portion 42b in order from the main body portion 14q side, and the outer portion 42b has a portion thicker than the root portion 42a. According to such a configuration, it is easy to bend the protruding seal portion 42 at the base portion 42a. Further, the protruding seal portion 42 is preferably provided across the bottom portion 14c and the body portion 14b of the main body portion 14q, as shown in FIGS. 17C to 17D. The outer portion 42b includes a thick portion 42b1 and a thin portion 42b2 having a smaller wall thickness than the thick portion 42b1, and the thin portion 42b2 is provided at a position adjacent to the boundary between the bottom portion 14c and the body portion 14b. If the thick part 42b1 is provided at the boundary between the bottom part 14c and the body part 14b, when trying to bend the protruding seal part 42, the thick parts 42b1 will interfere with each other, making it difficult to bend the protruding seal part 42. By providing the thin wall portion 42b2 at the boundary between the bottom portion 14c and the body portion 14b, the protruding seal portion 42 can be easily bent even when the protruding seal portion 42 is provided across the bottom portion 14c and the body portion 14b. The thick portion 42b1 is preferably thicker than the root portion 42a. It is preferable that the thin portion 42b2 has a smaller wall thickness than the root portion 42a.

<Surface treatment of inner preform 14>
When forming the inner preform 14 by direct blow molding, it is possible to make the inner preform 14 thinner than when forming the inner preform 14 by injection molding, and as a result, the inner bag 4 can also be made thinner. This is possible, and the inner bag 4 may include a thin portion having a wall thickness of 100 μm or less. The adhesion between the inner bag 4 and the outer shell 3 tends to become stronger as the inner bag 4 becomes thinner. Further, depending on the combination of materials for the inner preform 14 and the outer preform 13, the shrinkage rate of the inner bag 4 may be larger than the shrinkage rate of the outer shell 3 in the cooling process after biaxial stretch blow molding.

In such a case, the inner bag 4 does not contract uniformly, but selectively contracts in areas of the inner bag 4 where the adhesion to the outer shell 3 is relatively weak, and as a result, the inner bag 4 4, wrinkles may be formed and the aesthetic appearance may deteriorate.

In order to solve such a problem, in this embodiment, the inner preform 14 is provided with an uneven shape or has a lubricant on the outer surface of the region including the region corresponding to the thin-walled region. , is adopted. Both the uneven shape and the lubricant reduce the adhesion between the inner bag 4 and the outer shell 3, allowing the inner bag 4 to contract uniformly and suppressing wrinkles.

Methods for forming the uneven shape include a method of forming the uneven shape by post-processing the inner preform 14, and a method of forming the uneven shape on the shaping surface of a split mold for forming the inner preform 14. Examples include a method of transferring, a method of mixing particles into the resin constituting the inner preform 14, and reflecting the shape of the particles on the surface of the inner preform 14 to form an uneven shape.

Examples of methods for forming the uneven shape by post-processing include a method of rubbing the surface of the inner preform 14 with a sandpaver, and a method of sandblasting the inner preform 14. Examples of methods for forming the uneven shape on the shaped surface include rubbing the shaped surface with a sandpaver and sandblasting the shaped surface. Examples of the particles to be mixed with the resin include inorganic particles (eg, synthetic silicates such as talc and synthetic zeolites). The particle size is, for example, 1 to 50 μm, and the particle proportion is, for example, 0.5 to 10% by mass, preferably 1 to 5% by mass. This method is preferable since the adhesion between the inner bag 4 and the outer shell 3 is significantly reduced when the uneven shape is formed by post-processing.

Any lubricant that has a peeling effect can be used. The lubricant may be applied to the outer surface of the inner preform 14, or the lubricant may be mixed with the resin constituting the inner preform 14 so that it is present on the outer surface of the inner preform 14 by bleed-out.

It is preferable that the uneven shape has a random shape. Further, it is preferable that the uneven shape has an arithmetic mean roughness Ra of 1 to 200 μm. In this case, the adhesion between the inner bag 4 and the outer shell 3 can be particularly effectively reduced. Ra is specifically, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 30 , 40, 50, 60, 70, 80, 90, 100, 150, 200 μm, and may be within a range between any two of the numerical values exemplified here. Arithmetic mean roughness Ra can be measured in accordance with JIS B 0601:2013.

Other embodiments will be described below. The content described in the first embodiment can also be applied to the following embodiments unless it contradicts the spirit thereof.

2. Second Embodiment In the first embodiment, the protruding seal portion 42 that is not bent is formed by direct blow molding, and the protruding seal portion 42 is bent by post-processing to form a bent structure. On the other hand, in this embodiment, as shown in FIG. 25, a bent structure is formed in the protruding seal portion 42 when the inner preform 14 is directly blow molded. Even with such a configuration, the same effect as in the first embodiment can prevent the seal portion 43 from being stretched during biaxial stretch blow molding. According to this embodiment, the effort of post-processing can be saved.

3. Third Embodiment In this embodiment, the stretch suppressing structure is formed by remelting the protruding seal portion 42 after direct blow molding of the inner preform 14 to reduce its surface area. By remelting, the protruding seal portion 42 becomes bulky and increases in rigidity, so that it functions as a stretch restraining structure.

Preferably, before remelting, the aspect ratio defined by [height of protruding seal portion 42/thickness of protruding seal portion 42] is 3 or more, and the aspect ratio is reduced by remelting. . That is, in direct blow molding, as shown in FIGS. 26A to 26C, the protruding seal portion 42 is formed into a thin film shape, and the thin film protruding seal portion 42 is remelted into a lump. By forming the protruding seal portion 42 in the form of a thin film, the non-barrier region 44 where the gas barrier layer 14j is not provided becomes narrower, and in addition, the protruding seal portion 42 becomes easier to re-melt.

The thickness of the protruding seal portion 42 is, for example, 0.1 to 0.5 mm, preferably 0.1 to 0.3 mm, and specifically, for example, 0.1, 0.2, 0.3, 0.5 mm. 4.0.5 mm, and may be within a range between any two of the numerical values exemplified here. The height of the protruding seal portion 42 is, for example, 1.0 to 4.0 mm, preferably 1.0 to 3.0 mm, and specifically, for example, 1.0, 1.5, 2.0, 2. .5, 3.0, 3.5, 4.0 mm, and may be within the range between any two of the numerical values exemplified here. The values of the aspect ratio before remelting and [aspect ratio before remelting - aspect ratio after remelting] are, for example, 3 to 20, respectively, and specifically, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, and may be within the range between any two of the numerical values exemplified here.

It is preferable that the main body portion 14q is provided with a groove 14r along the protruding seal portion 42. In this case, the molten resin produced by remelting can be accommodated in the groove 14r.

4. Fourth Embodiment In this embodiment, as shown in FIG. 27, similarly to the first embodiment, a bent structure is formed by bending the protruding seal portion 42 in post-processing. This embodiment functions as a stretch suppressing structure by the same effect as the first embodiment, except that there is no groove 14r.

5. Fifth Embodiment In this embodiment, as shown in FIG. 28, similarly to the first embodiment, a bent structure is formed by bending the protruding seal portion 42 in post-processing. This embodiment functions as a stretch suppressing structure by the same effect as the first embodiment.

6. Sixth Embodiment In this embodiment, as shown in FIG. 29, the mouth portion 14a of the inner preform 14 is longer than that of the first embodiment, and the shape of the protruding seal portion 42 is that of the second embodiment. This embodiment is the same as the first embodiment except for this point. By preparing the outer preform 13 and mouth attachment member 8 having dimensions that match the inner preform 14 of this embodiment, the double container 1 can be manufactured in the same manner as in the first embodiment. In this embodiment, the protruding seal portion 42 may have the configuration of the first or third to fifth embodiments.

7. Seventh Embodiment In this embodiment, as shown in FIG. 30, a cam mechanism 31 is configured by a cam convex portion 14s provided on the inner preform 14 and a cam rail 13e provided on the outer preform 13, and the cam mechanism 31 is configured in the reverse screw loosening direction. The inner bag 4 moves in the direction of coming out of the container body 2 by rotation, the outer preform 13 is provided with an engaging convex portion 13f, and the shape of the protruding seal portion 42 is the same as that of the second embodiment. This embodiment is similar to the first embodiment except for certain points.

The double container 1 can be manufactured in the same manner as in the first embodiment using the mouth attachment member 8 that is compatible with the inner preform 14 and outer preform 13 of this embodiment. The mouth attachment member 8 may be configured to firmly engage the engagement convex portion 13f in the circumferential direction and become unrotatable relative to the outer shell 3, as described in the first embodiment. It is also possible to use one that engages with the engagement convex portion 13f in the circumferential direction to such an extent that it can rotate when the inner plug rotation torque T2 is applied. In the former case, a sorting band that engages with the engaging convex portion 13f is provided on the mouth attachment member 8, and the mouth attachment member 8 can be removed by separating the sorting band. In the latter case, the spout mounting member 8 can be removed by applying a torque equal to or higher than the inner stopper rotation torque T2 to the spout mounting member 8 without performing an operation such as separating the separation band.

In this embodiment, the protruding seal portion 42 may have the configuration of the first or third to fifth embodiments.

Various test examples related to the above embodiment will be described below.

1. Test example 1 (demonstration of the effect of the stretch suppressing structure)
・Sample 1
In sample 1, as shown in FIG. 31, a preform 15 is formed by covering an inner preform 14 having a protruding seal portion 42 without a stretch suppressing structure with an outer preform 13 shown in FIG. 15 is heated to 110° C. (temperature at the center of the height direction of the preform 15) and biaxially stretched blow molded to form the shape shown in FIG. 2 (however, the mouth portion 5 has the shape shown in FIG. 31). Container body 2 (capacity 200 mL) was manufactured.

The inner preform 14 was manufactured by direct blow molding. The layer structure of the inner preform 14 was, in order from the inside, inner layer [polypropylene/adhesive resin]/gas barrier layer [EVOH]/outer layer [adhesive resin/polypropylene/polypropylene containing 5% by mass of talc]. The thickness of each layer is measured at four points in the circumferential direction (two points in the parting line direction and two points in the direction perpendicular to the parting line) at the center of the inner preform 14 in the height direction, and the measured values are averaged. The average wall thickness was obtained by this. The wall thickness ratio was obtained by dividing the wall thickness of each layer by the wall thickness of the entire inner preform 14. Ta. The results obtained are shown in Table 1.

The outer preform 13 was manufactured by injection molding PET (model: titanium catalyst grade, manufactured by Teijin) at 300°C to form the outer preform shape, and then rapidly cooling it to 20°C. The molten PET was turned into an amorphous state by rapid cooling. The outer preform 13 had an average thickness of 750 μm at the center in the height direction.

The body of the inner bag 4 of the container body 2 obtained by biaxial stretch blow molding has a height of 120 mm, and the wall thickness of each layer of the inner bag 4 was measured at eight measurement points at a height of 60 mm from the bottom surface. was measured and the average wall thickness was obtained by averaging the measured values. The wall thickness ratio was obtained by dividing the wall thickness of each layer by the wall thickness of the entire inner bag 4. The results obtained are shown in Table 2.

When the inner bag 4 was pulled out from the container body 2 and the state of the protruding seal portion 42 was checked, it was found that the outer layer and gas barrier layer were torn, and the inner layer was exposed.

・Sample 2
In Sample 2, the protruding seal part 42 having the structure shown in FIG. 28 was formed by direct blow molding, and then the protruding seal part 42 was bent to form a stretch suppressing structure. Container body 2 was manufactured in the same manner as Sample 1 in other respects.

Similar to Sample 1, when the state of the protruding seal portion 42 was checked, no tearing had occurred in the outer layer or the gas barrier layer.

2. Test example 2 (demonstration of the effect of providing an uneven shape on the outer surface of the inner preform 14)
・Sample 3
In Sample 3, the container body 2 was manufactured in the same manner as Sample 1 except that the inner preform 14 had a single layer structure of polypropylene. The body of the inner bag 4 had a height of 120 mm, and the wall thickness of the inner bag 4 was measured at eight measurement points at each height position in 10 mm increments. The average wall thickness of the connecting portion is the average of the measured values at the center of the four connecting portions 2b, the average wall thickness of the corner portion is the average of the measured values at the center of the four corner portions 2a, and the average wall thickness is , is the average of the measured values at eight measurement points. The results obtained are shown in Table 3.

When the appearance of the container body 2 after cooling was checked, it was found that many vertical streaks were formed.

・Sample 4
In sample 4, after the inner preform 14 was manufactured by direct blow molding, the outer surface of the inner preform 14 was rubbed with #320 sandpaper to form an uneven shape on the surface of the inner preform 14. Container body 2 was manufactured in the same manner as Sample 3 in other respects. When the appearance of the container body 2 after cooling was checked, it was found that the inner bag 4 had shrunk uniformly and no vertical streaks were formed.

・Sample 5
In sample 4, the inner preform 14 was manufactured by direct blow molding using a split mold in which an uneven shape was formed by sandblasting. Container body 2 was manufactured in the same manner as Sample 3 in other respects. When the appearance of the container body 2 was checked after it had been cooled, it was found that although some vertical streaks were formed, they were much milder than in Sample 3.

・Sample 6
In Sample 6, the container body 2 was manufactured in the same manner as Sample 3, except that 3% by mass of talc, which is a synthetic silicate, was added as inorganic particles to polypropylene. When the appearance of the container body 2 after cooling was checked, no vertical streaks were formed.

・Sample 7
In Sample 7, the container body 2 was manufactured in the same manner as Sample 3, except that 3% by mass of synthetic zeolite was added as inorganic particles to polypropylene. When the appearance of the container body 2 after cooling was checked, no vertical streaks were formed.

3. Test example 3 (demonstration of final residual amount reduction effect by squeezing out inner bag 4)
Test No. under the conditions shown in Table 4. 1 to 10 were carried out.

・Test No. 1
Test No. In Example No. 1, the container body 2 was manufactured under the same conditions as Sample 3, and the container body 2 was filled with the contents having the viscosity shown in Table 4 in the filling amount shown in the table. Thereafter, a cap 8a shown in FIG. 1 was attached to the opening 5 of the container body 2.

Next, the overcap 27 was removed and the container body 2 was tilted to discharge the contents until no more contents came out, and the remaining amount after that was measured (residual amount after tilting). Next, the inner bag 4 was pulled out from the container body 2 by rotating the inner stopper 26, and the inner bag 4 was squeezed to further discharge the contents (amount remaining after squeezing).

・Test No. 2
Test No. Test No. 2 was the same as Test No. 2, except that the inner preform 14 was formed by injection molding of PET. The test was conducted in the same manner as in Example 1.

・Test No. 3-4 and 7-10
Test No. 3 to 4 and 7 to 10 are test No. The test was conducted in the same manner as in 1 and 2.

・Test No. 5-6
Test No. In Nos. 5 and 6, after pouring, the bottom 7 of the container body 2 was lightly tapped to discharge the contents until no more came out, and the amount remaining after that was measured (residual amount after tapping). For other points, test No. The test was conducted in the same manner as in 1 and 2.

Test No. In all cases Nos. 1 to 10, the final residual amount could be reduced by squeezing out the inner bag 4. No. By comparing Test No. 1 and Test No. 2, the inner bag 4 was made of PP with excellent flexibility. It was found that the amount remaining after squeezing was smaller in case 1. Further, the amount remaining after pouring significantly increased as the viscosity increased, whereas the amount remaining after squeezing did not increase as much as the amount remaining after pouring even when the viscosity increased.

1 : Double container 2 : Container body 2a : Corner part 2b : Connection part 2c : Bent shape 3 : Outer shell 3a : Open end 3l : Cam rail 3m : Engagement recess 3n : Engagement convex part 4 : Inner bag 4c : Protrusion Portion 4c1: Projecting tube 4c2: Engaging convex portion 4c3: Tapered surface 4c4: Contact flange 4c5: Annular convex portion 4c6: Lower surface 4c7: Lower surface 4c8: Tapered surface 4d: Inner bag body 4e: Outer layer 4e1: Outermost layer 4e2: Adhesive layer 4g: Cam convex portion 4h: Engagement convex portion 4i: Inner layer 4i1: Innermost layer 4i2: Repro layer 4i3: Adhesive layer 4j: Gas barrier layer 4k: Expanded diameter structure 4l: Open end 4m: Engagement portion 4q: Main body Part 5: Mouth 5b: Flange 5c: Opening end 6: Body 6b: Shoulder 6c: Body 7: Bottom 7a: Recess 8: Mouth attachment member 8a: Cap 13: Outer preform 13a: Mouth 13b : Body part 13c : Bottom part 13d : Annular convex part 13e : Cam rail 13f : Engagement convex part 14 : Inner preform 14a : Mouth part 14b : Body part 14c : Bottom part 14d : Projection part 14e : Outer layer 14i : Inner layer 14j : Gas barrier layer 14l: Expanded diameter structure 14m: Engaging portion 14n: Contact flange 14o: Opening end 14p: Burr 14q: Body portion 14r: Groove 14s: Cam convex portion 15: Preform 15a: Mouth portion 15b: Body portion 15c: Bottom part 26 : Inner plug 27 : Overcap 27a : Outer cylinder 27b : Intermediate cylinder 27c : Inner cylinder 27d : Top plate 27e : Knurling 27f : Female screw part 28 : Main body part 28a : Outer cylinder 28b : Inner cylinder 28c : Annular convex part 28d: Engagement convex portion 28e: Top plate 28f: Discharge tube 28g: Mounting tube 28h: Male screw portion 28i: Knurl 30: Connecting portion 31: Cam mechanism 32: Opening portion 32a: Engagement tube 33: Shrink film 33a: Easy cutting line 33b: Easy cutting line 33c: Upper part 33d: Lower part 34: Cylindrical parison 35: Divided mold 35a: Pinch-off part 36: Divided mold 36a: Pinch-off part 38: Molded body 39: Burr 40: Bag Part 41 : Annular recess 41a : Annular convex part 42 : Protruding seal part 42a : Root part 42b : Outer part 42b1 : Thick part 42b2 : Thin part 43 : Seal part 43a : Seal surface 44 : Non-barrier area

Claims (6)

A method for manufacturing a double container, comprising the step of biaxially stretching blow molding a preform formed by covering an inner preform with an outer preform to produce a container body having an inner bag and an outer shell covering the inner bag. There it is,
The inner preform is formed by direct blow molding using a molten cylindrical parison,
The mouth of the inner preform is provided with an engaging part used for pulling out the inner bag from the container body,
D1/D3 is 1.5 or more, where D1 is the outer diameter of the portion of the inner preform with the largest outer diameter at the mouth, and D3 is the outer diameter of the cylindrical parison;
The method, wherein the open end of the inner preform is provided with an enlarged diameter structure that suppresses deformation of the mouth. The method according to claim 1,
A method in which D1/D3 is 2 or more. The method according to claim 1,
The inner preform has a wall thickness of 1.5 mm or less at the open end. The method according to claim 1,
If the total height of the inner preform is H, and the outer diameter of the inner preform at a height position where the height from the bottom of the inner preform is 0.1H is D2, then D2/D1 is 0. 35 or more, method. The method according to claim 1,
A method in which D2/D1 is 0.5 or more. The method according to any one of claims 1 to 5,
In the direct blow molding, a molded body having a shape in which a bag portion is connected to the open end of the inner preform is formed,
The method wherein the inner preform is formed by cutting the bladder from the molded body.