JP6587830B2 - Stretch blow double container and manufacturing method thereof - Google Patents

Description

  The present invention relates to a stretch blow double container and a method for producing the same. More specifically, the present invention is obtained by stretch blow molding a double structure preform comprising an outer cylinder preform and an inner cylinder preform. And a manufacturing method thereof.

  Conventionally, a double-structure container having a double structure composed of an inner cylinder and an outer cylinder has been put to practical use as a container for storing seasoning liquid such as soy sauce, for example, as a delami bottle. That is, such a delamination bottle is used in combination with a cap with a check valve, and the contents filled in the inner cylinder body are capped by pressing the body wall of the bottle from the outside to be recessed. When the discharge of the contents is terminated by stopping the pressing of the bottle body wall, the air is not introduced into the inner cylinder by the action of the check valve, It will be introduced into the space between the inner cylinder and the outer cylinder through a different flow path from the cap extraction path. As a result, the inner cylinder contracts by the amount that the contents are discharged, and the inner cylinder contracts each time the contents are discharged. In the delamination bottle in which the contents are discharged by such a method, the contents can be dispensed and air can be effectively prevented from entering the inner cylinder filled with the contents. There is an advantage that it can be effectively avoided and the freshness of the contents can be maintained for a long time. Further, by setting a certain air layer between the inner cylinder and the outer cylinder, it can be used as a heat-insulating container having the effect of keeping the contents warm and cold.

The double structure container used as a delami bottle as described above is generally manufactured by direct blow molding. That is, it is manufactured by forming a double-structure pipe by melt extrusion, pinching off the lower end of the pipe, and then blowing it into a bottle shape by blowing a blow fluid.
However, when manufacturing a double-structured container by direct blow molding, the process from melt extrusion to bottle molding is performed all at once, so it is difficult to pick a large number of items, and the productivity is low, so the cost is high. There's a problem. In direct blow molding, an olefin resin is often used, and the transparency of the content is low, so the visibility of the contents is difficult.

For this reason, the manufacturing method of the double structure container by stretch blow molding is examined. That is, in the stretch blow molding method, a test tube-shaped container preform is once molded by injection molding or the like, and this preform is heated to a stretch molding temperature (more than the glass transition point and less than the melting point). In this method, the blown fluid is blown into the container shape and the container preform can be mass-produced. Productivity is high, and there is little variation in the container weight and volume. This is because there is an advantage that the container can be manufactured, and in particular, the cost can be reduced. Furthermore, in stretch blow molding, a highly transparent resin such as PET can be used, so the visibility of the contents can be improved.
For example, Patent Documents 1 to 3 disclose a method of manufacturing a double container by such stretch blow molding.

  When forming a double container by stretch blow molding, the inner cylinder forming preform is inserted and fixed inside the outer cylinder forming preform. Since the molding is performed by blowing the blow fluid, it becomes a problem how to secure an introduction path for introducing air between the outer surface of the molded inner cylinder and the inner surface of the outer cylinder. . For example, the known technology described above employs means for forming a groove or a ridge in the preform or forming an air hole in the bottom of the preform in order to form the air introduction path. For this reason, the mold structure also becomes complicated.

  In spite of such contrivance, in the stretch blow double container formed by a conventionally known method, the air introduction path may not function effectively, and the air between the inner cylinder body and the outer cylinder body may not function. However, each time the contents are repeatedly discharged, it becomes difficult to discharge the contents. That is, if air is not replenished between the inner cylinder and the outer cylinder, the inner cylinder and the outer cylinder are in close contact with each other and are maintained in a recessed state, so that the contents are effectively discharged as the content decreases. It will not be possible.

Patent No. 3796595 Japanese Patent No. 4281454 Japanese Patent No. 3745897

  Therefore, an object of the present invention is to stably introduce air between the inner cylinder and the outer cylinder, and to always effectively discharge the contents filled in the inner cylinder. Another object of the present invention is to provide a stretch blow double container and a method for producing the same.

According to the present invention, in the stretch blow double container comprising the outer cylinder and the inner cylinder inserted into the outer cylinder,
The outer cylinder includes a neck, a shoulder connected to the neck, a trunk extending downward from the shoulder, and a bottom closing the lower end of the trunk, and the shoulder, trunk, and The bottom is shaped by stretching the inner bag,
The inner cylindrical body is composed of a neck portion and a bag-like portion that is continuous with the neck portion and shaped by stretch blow,
Concavities and convexities are formed between the inner surface of the shoulder portion of the outer cylinder and the outer surface of the bag-like portion of the inner cylinder to temporarily engage them, and at least the contents in the inner cylinder In the state filled with, the unevenness is held in a non-engaged state, whereby an air layer is formed between the inner surface of the outer cylinder and the outer surface of the inner cylinder. A stretch blow double container is provided.

In the stretch blow double container of the present invention,
(1) An air hole communicating with the air layer is formed in a neck portion of the outer cylindrical body,
(2) Each of the irregularities extends in the container axial direction,
Is preferred.

According to the present invention, the preform for the outer cylinder and the preform for the inner cylinder , both of which have a test tube shape and have a neck part which is a non-molded part and a tubular part which is stretch blow molded prepare the door, a process for producing stretch blow double container by performing stretch blow molding in a state of inserting the preform for the inner cylinder inside of the preform for the outer cylindrical body,
Assembled dual structure preform by inserting the inner tube body preform to the outer tube-body preform,
The assembly of the double structure preform is placed in a blow mold having a recess or projection for forming irregularities for temporary engagement on the shoulder of the outer cylinder, and stretch blow molding is performed.
After the stretch blow molding, the outer cylinder and the inner cylinder shaped in the container shape are displaced relative to each other in the circumferential direction, so that the temporary engagement irregularities formed on the outer cylinder and the inner cylinder are reduced. A method for producing a stretch blow double container is provided, characterized in that the stretch blow double container is held in a disengaged state.
In this manufacturing method,
(3) An air hole is formed in the neck of the outer cylinder preform ,
Is preferred.

In the stretch blow double container of the present invention, a bag-like inner cylinder is inserted and held inside the outer cylinder, and the outer cylinder and the inner cylinder can be temporarily engaged with each other. Concavities and convexities are formed, and the concavities and convexities exist in a non-engaged state. That is, the unevenness exists in a state of being displaced so as not to engage with each other. As a result, it is the greatest feature of the present invention that an air layer is formed between the outer cylinder and the inner cylinder.
That is, when a double container is manufactured by performing stretch blow molding with the inner cylinder preform inserted into the outer cylinder preform, the inner cylinder preform is stretched and stretched. The outer surface of the inner cylinder preform is in close contact with the inner surface of the outer cylinder preform, the outer cylinder preform is stretched, and the outer surface of the outer cylinder preform is in close contact with the blow mold surface and cooled. Thus, the inner cylinder preform and the outer cylinder preform are shaped into a container shape in close contact with each other, and a stretch blow double container is obtained. For this reason, in this state, the outer surface of the bag-shaped portion of the inner cylinder is in close contact with the inner surface of the shoulder portion of the outer cylinder. However, in the present invention, normally, an air layer (void) is positively formed in an intimate contact portion.

  In the present invention, an air hole formed in the neck portion of the outer cylindrical body communicates with the gap that becomes such an air layer. For this reason, after pressing the barrel of the outer cylinder to discharge the contents filled in the bag-like inner cylinder, the pressing of the outer cylinder is stopped and the barrel of the outer cylinder is elasticized to the original shape. When returned, an air layer (gap) is formed between the inner surface of the shoulder of the outer cylinder and the outer surface of the inner cylinder, so that the air passes through the air hole formed in the neck of the outer cylinder. Since air is introduced between the inner surface of the barrel of the outer cylinder that has been restored to its original shape through the layers and the outer surface of the inner cylinder that has been recessed and contracted, the shape of the inner cylinder that has been contracted by the recess is maintained as it is. Will be. That is, when the body of the outer cylinder is pressed again and deformed, the inner cylinder is pressed through the air layer, the contents in the inner cylinder are discharged, and the bag-like part of the inner cylinder is further contracted. Will do. Thus, in the present invention, the contents can be repeatedly discharged stably.

  For example, if the air layer as described above is not formed and the inner surface of the outer cylinder is in close contact with the outer surface of the inner cylinder, the contents are discharged and the inner cylinder is in a decompressed state. Air is not effectively introduced between the inner surface of the barrel portion of the cylindrical body and the outer surface of the barrel portion of the inner cylindrical body, and both the outer cylindrical body and the inner cylindrical body are maintained in a recessed state. In other words, the more the content is reduced, the more difficult it is to press, and eventually it becomes difficult to discharge the content stably.

  In addition, the stretch blow double container of the present invention uses a double preform (preform for outer cylinder and preform for inner cylinder) for stretch blow molding to form an outer cylinder and an inner cylinder. A double container precursor in which the irregularities formed on each of the bodies are engaged with each other is molded, and with respect to this precursor, the outer cylinder and the inner cylinder that are in close contact with each other are formed in the circumferential direction. By relatively shifting the position, it can be easily manufactured.

The side sectional view of the stretch blow double container of the present invention. AA plane sectional drawing of the double container of FIG. The partial expanded side sectional view which expands and shows the principal part of the stretch blow double container of FIG. The figure for demonstrating the method of forming the air layer in the stretch blow double container of FIG. The sectional side view which shows the state by which the cap with a non-return valve was mounted | worn with the neck part of the stretch blow double container of FIG.

  Referring to FIGS. 1 to 3, the stretch blow double container of the present invention generally indicated by 20 includes an outer cylinder 1 and an inner cylinder 3 inserted into the outer cylinder 1. It is configured.

  The outer cylinder 1 has a neck portion 1a, a shoulder portion 1b that extends outwardly from the lower end of the neck portion 1a, a trunk portion 1c that extends downward from the shoulder portion 1b, and a lower end of the trunk portion 1c. Like the outer cylinder 1, the inner cylinder 3 extends downward from the neck 3a, the shoulder 3b that extends outward from the lower end of the neck 3a, and the shoulder 3b. And a bottom 3d that closes the lower end of the body 3c.

  The neck portions (nozzle portions) 1a and 3a of the outer cylindrical body 1 and the inner cylindrical body 3 are both fixed portions (non-stretched portions) that are not blow-drawn in stretch blow molding described later, and have rigidity. The shoulders 1b and 3b below the necks 1a and 3a, the trunks 1c and 3c, and the bottoms 1d and 3d are all stretch-formed parts formed by blow-drawing.

  In the outer cylinder 1, a support ring 5 is formed on the outer surface of the neck 1 a to be used for transporting and gripping the outer cylinder 1, and further, a shoulder 1 b connected to the lower end of the neck 1 a, a trunk The 1c and the bottom 1d are formed to have a shape-retaining thickness. In particular, the body 1c is easily recessed when pressed by hand from the outside, but when the pressure is released, it quickly returns to its original shape. It is supposed to be.

On the other hand, the inner cylinder 3 is inserted into the outer cylinder 1 described above, but the neck 3a protrudes from the neck 1a of the outer cylinder 1, and this protruding portion is described later. A thread 9 for engaging and holding the check valve cap is formed, and a ring-shaped projection 7 having a smaller diameter than the support ring 5 of the outer cylinder 1 is formed in a lower portion of the thread 9. The upper end of the neck 1 a of the outer cylinder 1 is in contact with the lower surface of the ring-shaped protrusion 7. That is, the ring-shaped protrusion 7 is used for gripping and transporting the inner cylinder 3 and also functions as a member that regulates the position of the outer cylinder 1.
Moreover, the extending | stretching shaping | molding part (Shoulder part 3b, trunk | drum 3c, and bottom part 3d) of the inner cylinder 3 is a part which does not have a bag-like form retainability, and is formed thinly.

The inner surface of the upper end portion of the neck portion 1a of the outer cylindrical body 1 as described above is in close contact with the outer surface of the lower portion of the ring-shaped protrusion 7 of the neck portion 3a of the inner cylindrical body 3, whereby the inner cylindrical body 3 is The outer cylinder 1 is firmly held. This close contact portion is shown in FIG.
Further, a gap 11 is formed between the inner surface of the neck 1 a of the outer cylinder 1 and the outer surface of the neck 3 a of the inner cylinder 3 below the fitting part A. An air hole 13 is provided in the neck portion 1a of the outer cylindrical body 1 so as to communicate with the air cylinder.
That is, in the lower part of the fitting portion A, the inner diameter of the neck portion 1a of the outer cylindrical body 1 is formed larger than the outer diameter of the neck portion 3a of the inner cylindrical body 3, corresponding to this difference. Thus, the gap 11 is formed in a circumferential shape.
Also, the inner diameter of the tubular portion (stretched portion) below the neck portion of the outer cylinder preform is such that the inner cylinder preform can be smoothly inserted into the outer cylinder preform. It is set slightly larger than the outer diameter of the tubular part (stretched part) below the neck part of the preform. This is for venting (air venting) during insertion.

In such a double container 20, in the present invention, the shoulder portion 1 b of the outer cylinder 1 is formed with a convex portion 15 a that protrudes outward and extends in the axial direction. The shoulder 3b of the cylindrical body 3 is also formed with a convex portion 15b that protrudes outward and extends in the axial direction. The convex portions 15a and 15b can be temporarily engaged. For example, the convex portion 15b of the inner cylindrical body 3 has the same shape as the concave portion formed by the convex portion 15a of the outer cylindrical body 1. It has a shape that fits perfectly inside.
In the present invention, the convex portions 15a and 15b that can be temporarily engaged with each other as described above are present in a position shifted in the circumferential direction as shown in FIG. An air layer 17 (i.e., a gap) is formed between the inner surface of the shoulder portion 1 b of the first cylinder 1 and the outer surface of the shoulder portion 3 b of the inner cylinder 3. It communicates with the hole 13.

That is, a test tubular preform (inner cylinder preform) used for molding the inner cylinder 3 is inserted into a test tubular preform (outer cylinder preform) used for molding the outer cylinder 1. In this state, when blow molding is performed by blowing a blow fluid into the inner cylinder preform, the outer cylinder preform is expanded and molded by stretching the inner cylinder preform. Further, the stretch-formed part (shoulder part 3b, body part 3c and bottom part 3d) below the neck part 3a of the inner cylindrical body 3 is formed below the neck part 1a of the outer cylinder body 1 (shoulder part 1b, trunk part) 1c and bottom d) are obtained in close contact with the inner surface.
However, in the present invention, as can be understood from FIG. 2, convex portions 15 a and 15 b that can be temporarily engaged are formed on the shoulder portion 1 b of the outer cylindrical body 1 and the shoulder portion 3 b of the inner cylindrical body. In addition, since the positions of both are shifted in the circumferential direction, the air layer 17 is originally formed in a portion that should be in close contact with each other.

  In manufacturing the double container of the present invention having the above structure, after inserting the preform for the inner cylinder into the preform for the outer cylinder and heating these preforms to the stretch molding temperature Stretch blow molding is performed by blowing a blow fluid into the preform for the inner cylinder after appropriately stretching in the uniaxial direction with a stretch rod.

  That is, both the outer cylinder preform and the inner cylinder preform having the test tube shape are obtained by molding such as injection molding using a predetermined thermoplastic resin. Stretched to form shoulders 1b, 3b, trunks 1c, 3c and bottoms 1d, 3d by stretch molding at the lower part of the non-stretched portion. It is a molded part. By inserting and fixing the inner cylinder preform into such an outer cylinder preform, the upper end of the neck portion 1a is connected to the neck portion 3a as shown in FIGS. A space 11 that is in contact with the lower surface of the ring-shaped protrusion 9 and that is continuous with the air hole 13 formed in the neck portion 1a is formed on the outer surface of the neck portion 3a and the inner surface of the neck portion 1a. The molded portion is stretch blow molded to form shoulder portions 1b and 3b, trunk portions 1c and 3c, and bottom portions 1d and 3d.

By the way, when stretch blow molding is performed as described above, a concave portion corresponding to the above-described convex portion 15a is formed on the surface of the blow mold disposed so as to surround the stretch molded portion of the preform. Yes. For this reason, in the double container (precursor) immediately after stretch blow molding, as shown in FIG. 4A, the convex portion 15a and the inner cylinder formed on the shoulder 1b of the outer cylinder 1 The protrusions 15b formed on the shoulder 3b of the body 3 are engaged with each other, and therefore the outer cylinder 1 and the inner cylinder 3 are in close contact with each other. That is, the stretch-molded portion of the preform for the inner cylinder is stretched by blowing the blow fluid, and thereby, the stretch-molded portion of the preform for the outer cylinder is expanded to form a blow mold surface. This is because it is shaped into a shape.
Therefore, immediately after the stretch blow molding, the outer surfaces of the stretched portions (shoulder portion 3b, trunk portion 3c, bottom portion 3d) of the inner cylindrical body 3 are all (shoulder portion 1b, trunk portion 1c, The bottom 1d) is in close contact with the inner surface, and no air layer is formed between them.

However, in the present invention, the neck portion 1a of the outer cylindrical body 1 and the neck portion 3a of the inner cylindrical body 3 are relatively rotated with respect to the precursor of the double container formed as described above. That is, since the stretch-molded portions (shoulder portion 1b, body portion 1c, bottom portion 1d) of the inner cylinder 3 do not have a bag-like form-retaining property, the convexity shown in FIG. The shoulder 3b forming the portion 15b is easily bent and released from the concave portion formed by the convex portion 15a (temporary engagement is released), as shown in FIG. 4B. Further, the convex portion 15a and the convex portion 15b are displaced in the circumferential direction. As a result, as shown in FIGS. 1 and 3, the inner surface of the shoulder portion 1b of the outer cylindrical body 1 and the inner cylindrical body 3 An air layer 17 communicating with the air hole 13 through the gap 11 is formed between the outer surface of the shoulder 3b.
Even when the neck 1a of the outer cylinder 1 and the neck 3a of the inner cylinder 3 are relatively rotated as described above, the air hole 13 and the air gap 11 are formed because the air gap 11 is formed in a circumferential shape. The communication with is not interrupted.

  In the above-described present invention, the shoulder 1b of the outer cylinder 1 and the shoulder 3b of the inner cylinder 3 are respectively formed with convex portions 15a and 15b protruding outward. Instead of such a convex portion, a concave portion protruding inward can also be formed. In this case, convex portions corresponding to such concave portions are formed on the surface of the blow mold.

  Further, as shown in FIG. 2, in the above example, four convex portions 15 a and 15 b are formed point-symmetrically, but the shoulder portion 1 b of the outer cylindrical body 1 and the inner cylindrical body are formed. As long as the air layer 17 communicating with the gap 11 is formed between the three shoulder portions 3b, the number is not limited to four, but may be one or more convex portions 15a, 15b (or a recess) can also be formed. However, in general, in consideration of the appearance of the double container 20, the plurality of convex portions 15 a and 15 b (or concave portions) are usually formed point-symmetrically.

  Further, the axial lengths and heights of the convex portions 15a and 15b, or the degree of positional deviation between them (angle θ shown in FIG. 4), the shoulder portions 1b of the outer cylindrical body 1 and the inner cylindrical body 3 What is necessary is just to set to an appropriate range so that the air layer 17 which communicates with the space | gap 11 may be formed between the shoulder parts 3b, for example, if such an air layer 17 is formed, convex part 15a, 15b. May extend to the torso.

The double container 20 of the present invention having the above-described structure includes the neck 1a of the outer cylinder 1 and the inner cylinder 3 protruding from the neck 1a after the contents are stored in the inner cylinder 3. A cap with a check valve is attached to the nozzle portion formed from the neck portion 3a for use.
That is, in the double container 20 of the present invention, an air layer 17 is formed between the inner surface of the shoulder 1b of the outer cylinder 1 and the shoulder 3b of the inner cylinder 3 that should be in close contact with each other, The air layer 17 communicates with the air hole 13 through the gap 11 and effectively functions as an air introduction portion. For this reason, when the discharge operation of the content is performed by attaching a cap with a check valve and pressing the outer surface of the body portion 1 c of the outer cylinder body 1, the body portion 3 c of the outer cylinder body 1 and the inner cylinder body 3. The air can be effectively introduced between the bottom portion 3d and the bottom portion 3d, and the contents can be discharged stably.

FIG. 5 shows the state of the nozzle portion of the container 20 to which such a cap with a check valve is attached.
That is, the cap with a check valve indicated as 50 as a whole may have a conventionally known structure. For example, the cap main body 51 that covers the nozzle portion of the double container 20 and the nozzle And an inner plug 53 fitted in the opening at the upper end of the portion (opening of the neck 3a of the inner cylinder 3).
Although not shown in FIG. 5, the upper lid is normally hinged to the cap body 51, and the contents are discharged with the upper lid opened.

The cap body 51 is formed from a top plate portion 55 and a cylindrical side wall 57 that descends from the periphery of the top plate portion 55.
The top plate portion 55 is formed with an opening 59 for pouring contents at the center, and a pouring cylinder 61 serving as a guide for the contents to be poured extends upward from the periphery of the opening 59. Moreover, an opening 63 for introducing air is formed at the top of the top portion at a position that is outside the dispensing tube 61.
Further, on the inner surface of the cylindrical side wall 57, there is formed a screw projection 65 that engages with the screw 9 provided on the outer surface of the nozzle portion (neck portion 3a of the inner cylinder 3) of the double coupling container 20. The cap body 51 is stably held in a state where it is put on the nozzle portion by the screw engagement between the screw 9 and the screw projection 65.
One or both of the screw 9 and the screw projection 65 are intermittently cut, and even when they are engaged with each other, air flows through the cut-out portion. ing. Further, the lower end portion of the cylindrical side wall 55 is in close contact with the support ring 5 formed on the neck portion 1a of the outer cylindrical body 1, so that air does not leak from this portion.

  On the other hand, the inner plug 53 includes a first plug body 71 having a cylindrical shape that is fitted into the opening of the nozzle portion, and a second plug body 73 that is fitted into the first plug body 71. Yes.

The lower end portion (bottom portion) of the first plug body 71 is closed by the first valve 71a, and when the contents are discharged, the valve 71a is opened upward by the internal pressure of the container, and the opened portion is the contents. Things are going to pass.
In addition, an upper portion of the first plug 71 is provided with an outwardly extending flange 71b. The lower end of the flange 71b is in close contact with the upper end surface of the nozzle portion, so that the first The plug 71 is firmly held by the nozzle portion.

  Since the second plug body 73 is fitted into the upper opening of the first plug body 71, it has a cylindrical shape like the first plug body 1. An extending annular second valve 73a is provided. The second valve 73a is normally positioned so as to close the opening 63 formed in the top plate portion 55 of the cap body 51. However, after the discharge of the contents is finished, the second valve 73a hangs down and opens the opening 63. The air flows through the opening 63.

  That is, referring to FIG. 5, in order to discharge the contents from the double container 20 in which the inner cylinder 3 is filled with the contents, after opening the upper cover provided on the cap 50 with the check valve The outer surface of the body portion 1c (outer cylinder 1) of the container 20 is pressed to be recessed. Thereby, the trunk | drum 3c of the inner cylinder 3 is also dented, and the content in the inner cylinder 3 opens the 1st valve 71a upward by the pressing force, and as shown by the arrow P Then, it passes through the inside of the inner plug 53 (the first plug body 71 and the second plug body 73), and is further discharged to the outside through the opening 59 and the extraction tube 61. Thus, the content filled in the inner cylinder 3 is discharged by the amount of the depression of the inner cylinder 3.

  On the other hand, when the pressing of the outer surface of the body 1c (outer cylinder 1) of the container 20 is stopped, the body 1c is elastically restored to its original form, but the body 3c of the inner cylinder 3 is returned to the original state. Since it does not return elastically, a void in a reduced pressure state lower than the atmospheric pressure is generated between the inner cylinder 3 and the outer cylinder 1. For this reason, the first valve 73a of the second plug 73 hangs down and the opening 63 is opened. As a result, as shown by the arrow Q, air passes through the opening 63 and the outer surface of the nozzle portion. And the inner surface of the cap body 51 (cylindrical side wall 57), the air hole 13 formed in the nozzle part (neck part 1a of the outer cylinder 1), and the air layer 17 from the gap 11 Air will be introduced quickly.

  Thus, after air is introduced into the gap formed between the inner cylinder 3 and the body 1c of the outer cylinder 1, the outer surface of the body 1c (outer cylinder 1) of the container 20 is pressed again. Then, the air introduced into the gap is not released to the outside because the opening 63 is closed by the second valve 73. Therefore, the inner cylinder 3 is pressed and recessed through the air layer. As a result, the contents in the inner cylindrical body 3 are again discharged to the outside by the amount recessed as in the above case.

  In this way, the contents filled in the inner cylinder 3 are discharged by the pressed depressions, but even when the contents are discharged, air is still in the inner cylinder 3. Therefore, oxidative deterioration of the contents is effectively prevented, and the freshness of the contents is effectively maintained.

In the present invention, the outer cylinder 1 and the inner cylinder 3 can be formed of various thermoplastic resins as long as blow molding is possible as described above.
As such a thermoplastic resin, the following can be illustrated, for example.
Olefin resins such as low density polyethylene, high density polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene or α-olefins such as ethylene, propylene, 1-butene and 4-methyl-1-pentene Random or block copolymers, cyclic olefin copolymers, etc .;
Ethylene / vinyl copolymers, such as ethylene / vinyl acetate copolymer, ethylene / vinyl alcohol copolymer, ethylene / vinyl chloride copolymer, etc .;
Styrenic resin such as polystyrene, acrylonitrile / styrene copolymer, ABS, α-methylstyrene / styrene copolymer, etc .;
Vinyl resins such as polyvinyl chloride, polyvinylidene chloride, vinyl chloride / vinylidene chloride copolymers, polymethyl acrylate, polymethyl methacrylate, etc .;
Polyamide resin, for example, nylon 6, nylon 6-6, nylon 6-10, nylon 11, nylon 12, etc .;
Polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, and copolyesters thereof;
Polycarbonate resin;
Polyphenylene oxide resin;
Biodegradable resins, such as polylactic acid;
Of course, as long as the moldability is not impaired, a blend of these thermoplastic resins can also be used as the base resin.
In the present invention, the thermoplastic resins that are particularly preferably used are polyester resins and olefin resins, and further, air flows between the outer cylinder 1 and the inner cylinder 3 for the purpose of use. The outer cylinder preform 1 forming the body 1 does not necessarily require moisture and gas barrier properties, and polylactic acid having low moisture and gas barrier properties can also be suitably used.

Further, in order to provide gas barrier properties to the outer cylinder 1 and the inner cylinder 3, the outer cylinder preform and the inner cylinder preform for forming them may have a multilayer structure.
For example, an ethylene vinyl alcohol copolymer (saponified ethylene vinyl acetate copolymer) or an aromatic polyamide is used as an intermediate layer between the inner and outer layers formed from the polyester resin or olefin resin (or polylactic acid) described above. It is preferable to provide a gas barrier layer formed using a gas barrier resin such as the above, and it is most preferable to provide a gas barrier layer made of an ethylene vinyl alcohol copolymer. That is, an oxygen barrier property can be imparted by providing a gas barrier layer as an intermediate layer. In particular, an ethylene vinyl alcohol copolymer exhibits a particularly excellent oxygen barrier property, and therefore oxidative deterioration of the contents due to oxygen permeation can be achieved. It can suppress effectively and can secure the outstanding contents preservation nature.

  In addition, when the gas barrier layer as described above is provided, an adhesive resin layer can be provided in order to enhance adhesion with the inner and outer layers and prevent delamination, whereby an intermediate gas barrier layer can be formed. It can be firmly fixed to the inner and outer layers. Adhesive resins used for forming such an adhesive resin layer are known per se. For example, a carbonyl group (> C═O) is 1 to 100 meq / 100 g resin in the main chain or side chain, particularly 10 to 100 meq / 100 g. Resin contained in the amount of resin, specifically, olefin resin graft-modified with carboxylic acid such as maleic acid, itaconic acid, fumaric acid or its anhydride, amide, ester, etc .; ethylene-acrylic acid copolymer; An ion-crosslinked olefin copolymer; an ethylene-vinyl acetate copolymer; and the like are used as the adhesive resin.

  In the present invention, it is particularly preferable to provide the inner cylinder 3 with a high oxygen barrier property. Therefore, the inner cylinder 3 adopts the above-described multilayer structure, and the outer cylinder 1 is made of biolactic acid such as polylactic acid. Use of plastic is suitable for both performance and environmental aspects.

  The above-described double container of the present invention is extremely useful as a container for seasoning liquids such as soy sauce because it can maintain high freshness for a long period of time and can dispense the contents.

1: outer cylinder 1a: neck 1b: shoulder 1c: trunk 1d: bottom 3: inner cylinder 3a: neck 3b: shoulder 3c: trunk 3d: bottom 5: support ring 7: ring-shaped protrusion 9: screw Article 11: Air gap 13: Air hole 15a, 15b: Convex part 17: Air layer 20: Double container

Claims (5)

In the stretch blow double container consisting of the outer cylinder and the inner cylinder inserted into the outer cylinder,
The outer cylinder includes a neck, a shoulder connected to the neck, a trunk extending downward from the shoulder, and a bottom closing the lower end of the trunk, and the shoulder, trunk, and The bottom is shaped by stretching the inner bag,
The inner cylindrical body is composed of a neck portion and a bag-like portion that is continuous with the neck portion and shaped by stretch blow,
Concavities and convexities are formed between the inner surface of the shoulder portion of the outer cylinder and the outer surface of the bag-like portion of the inner cylinder to temporarily engage them, and at least the contents in the inner cylinder In the state filled with, the unevenness is held in a non-engaged state, whereby an air layer is formed between the inner surface of the outer cylinder and the outer surface of the inner cylinder. Stretch blow double container.   The stretch blow double container according to claim 1, wherein an air hole communicating with the air layer is formed in a neck portion of the outer cylindrical body. 3. The stretch blow double container according to claim 1 , wherein each of the irregularities extends in a container axial direction. Each of them has a test tube shape, and an outer cylinder preform and an inner cylinder preform having a neck part which is a non-molded part and a tubular part which is stretch blow molded are prepared, and the outer cylinder is prepared. a method for producing a stretch blow double container by a state of inserting the inner cylinder preform inside the body preform subjected to the stretching blow molding,
Assembled dual structure preform by inserting the inner tube body preform to the outer tube-body preform,
The assembly of the double structure preform is placed in a blow mold having a recess or projection for forming irregularities for temporary engagement on the shoulder of the outer cylinder, and stretch blow molding is performed.
After the stretch blow molding, the outer cylinder and the inner cylinder shaped in the container shape are displaced relative to each other in the circumferential direction, so that the temporary engagement irregularities formed on the outer cylinder and the inner cylinder are reduced. A method for producing a stretch blow double container, wherein the stretch blow double container is held in a disengaged state. The manufacturing method according to claim 4, wherein an air hole is formed in a neck portion of the outer cylinder preform .