JP7069698B2 - Double structure container - Google Patents

Description

The present invention relates to a double-structured container, and more particularly to a double-structured container including an outer container and an inner bag container inserted and held in the outer container.

Conventionally, a double-structured container having a double-structured structure consisting of an inner bag container and an outer container has been put into practical use as, for example, an airless bottle and a container for containing a seasoning liquid such as soy sauce. Such an airless bottle is used in combination with a cap with a check valve, and the contents filled in the inner bag container by squeezing and denting the body wall of the bottle, which is the outer container, from the outside. When the object is discharged from the pouring path formed in the cap and the discharge of the content is terminated by stopping the pressing of the body wall of the bottle, the air is introduced into the inner bag container by the action of the check valve. Instead, it will be introduced into the space between the inner bag container and the outer container through a flow path different from the pouring path of the cap. As a result, the inner bag container shrinks by the amount that the contents are discharged, and each time the contents are discharged, the inner bag container shrinks. In an airless bottle in which the contents are discharged by such a method, the contents can be dispensed and the intrusion of air into the inner bag container filled with the contents is effectively prevented, so that the contents are oxidatively deteriorated. There is an advantage that the freshness of the contents can be maintained for a long period of time.

By the way, as a method for manufacturing a double-structured container as described above, a resin having no adhesiveness to each other is selected as a resin for an outer container and a resin for an inner bag container, and direct using these resins is used. The mainstream method was to shape the container into a container by blow molding. That is, in this method, a pipe having a double structure is formed by melt extrusion using the above resin, the lower end of the pipe is pinched off, and then a blow fluid is blown into the pipe to shape it into a bottle. It is a method. However, this method has a problem that it is difficult to take a large number of pieces and the productivity is low because the process from melt extrusion molding to bottle molding is performed at once. There is also a problem that the strength of the outer container is low.

Therefore, recently, a method of manufacturing a double-structured container by stretch blow molding has been studied.
The preform-in-bottle method and the stack preform are widely known as this method.

In the preform-in-bottle method, for example, as described in Patent Document 1, an outer container is molded in advance by a known stretch blow molding, and a test tube-shaped inner bag preform is formed in the outer container. Is inserted, and in this state, blow fluid is supplied into the inner bag preform to perform blow molding. In this method, the outer container functions as a blow type, and the inner bag preform is shaped into a bag-shaped container shape. That is, in this method, stretch blow molding of the outer container and stretch blow molding of the inner bag container are sequentially performed.

Further, in the stack preform method, for example, as described in Patent Document 2, the preform for an outer container and the preform for an inner bag are molded by injection molding, and the preform for an inner bag is a preform for an outer container. Inserted inside to form a stack preform in which the preform for the outer container and the preform for the inner bag overlap, and this stack preform is held in the blow mold, and the preform for the inner bag inside the stack preform is held. It is a method of performing stretch blow molding by supplying a blow fluid inside. That is, in this method, the preform for the outer container is shaped into the shape of the container by the expansion of the preform for the inner bag, and the stretch blow molding for the outer container and the stretch blow molding for the inner bag container are performed. It is done at the same time.

In all of the double-structured containers obtained by stretch blow molding as described above, the mouth portion (non-stretched portion) of the inner bag container is held in a state of being fitted and fixed to the mouth portion (non-stretched portion) of the outer container. However, such a mouth portion is provided with a protrusion such as a cap with a check valve for fixing or adhering to a screw, or a support ring used for transporting a container or preform. When further heat resistance is imparted, crystallization treatment is performed.
However, in the double-structured container, unlike a normal container, an air introduction port for introducing air between the outer container and the inner bag container is formed at the mouth of the outer container, and the double-structured container has a double-structured structure. Therefore, the thickness of each of the inner bag and the mouth of the outer container tends to be designed to be relatively thin, so that there is a problem that the impact resistance (drop strength) is low. In particular, when the mouth is crystallized, the impact strength of the material decreases, and this tendency is remarkable. That is, when the container is dropped or the like, stress is concentrated on the air inlet portion or the like provided at the mouth portion of the outer container, and cracks or the like are likely to occur from this portion.
Further, in the case of blow molding, from the viewpoint of ensuring the shrinkage of the inner bag, it is necessary to firmly heat the airless container to the vicinity of the inner bag mouth to perform stretch molding, that is, to make the inner bag thinner. Since the vicinity of the portion is also unintentionally heated at the same time, there is also a problem that the dimensional change is likely to occur in the vicinity of the air inlet of the outer container. Such a dimensional change may impair the adhesion with the cap or the sealing property, and impair the function of the check valve provided on the cap.
Furthermore, when both the inner bag and the mouth of the outer container are crystallized, the flexibility of the material is reduced by the crystallization, so that the fit between the mouth of the inner bag container and the mouth of the outer container is good. It is difficult to firmly fix the mouth of the inner container to the mouth of the outer container without rattling, or in some cases, a gap is created between the two. Air may leak from parts other than the air inlet.

Patent No. 3201417 Japanese Unexamined Patent Publication No. 2016-210181

Therefore, an object of the present invention is a double-structured container composed of an outer container and an inner bag container inserted and held in the outer container and manufactured by stretch blow molding, in which impact resistance at the mouth is tolerated. It is an object of the present invention to provide a double-structured container having improved properties, dimensional changes, and even fitability.

According to the present invention, the air introduction comprises an outer container and an inner bag container inserted and held in the outer container, and air is introduced between the inner surface of the outer container and the outer surface of the inner bag container. In a double-structured container with a mouth
The outer container includes a non-crystallized opening portion which is a non-stretched portion, and a body portion and a bottom portion which are stretched portions.
The inner bag container includes a crystallization port portion which is a non-stretched portion and a bag-shaped portion which is a stretched portion, and the crystallization port portion is fitted and fixed to the non-crystallization port portion of the outer container. A double-structured container characterized by this is provided.

In the double-structured container of the present invention,
(1) A gap is formed between the inner surface of the non-crystallization opening portion of the outer container and the outer surface of the crystallization opening portion of the inner bag container.
(2) The air inlet is formed in the amorphous port of the outer container.
(3) The void communicates with the air inlet.
Is preferable.

The double-structured container of the present invention is obtained by a stretch blow molding method, but only the mouth of the inner bag container is crystallized, and the mouth of the outer container in which the air introduction port is formed is crystallized. It has an important feature in that it is not crystallized.
That is, in the double-structured container of the present invention, heat resistance is imparted by crystallizing the mouth of the inner bag container to form a crystallized mouth, for example, the inner bag container is hot-filled with the contents. Even when it is filled inside, its thermal deformation is effectively prevented. Further, the mouth portion of the outer container is not crystallized and is a non-crystallized mouth portion. Therefore, it has high flexibility and excellent impact resistance. For example, in the event of a drop impact, stress concentration on the air inlet portion is alleviated, and cracking from this portion is effectively prevented. Further, the flexibility of the non-crystallized opening portion brings about an improvement in the fitability with the hard crystallization opening portion of the inner bag container, and the crystallization opening portion of the inner bag container is firmly fitted without rattling. Can be fixed together. Further, such an improvement in the fitting property brings about an improvement in the adhesion between the mouth portion (non-crystallized mouth portion) of the outer container and the mouth portion (crystallization port portion) of the inner bag container, and the air introduction port. It is also possible to effectively prevent air leakage from parts other than the above.
Further, in the present invention, by providing a gap communicating with the air introduction port between the mouth of the outer container and the mouth of the inner bag container, the mouth of the outer container during blow molding, particularly air introduction. It is also possible to effectively suppress the dimensional change in the portion near the mouth.

Schematic side sectional view of the double structure container of this invention. The enlarged side sectional view of the main part in the double structure container of FIG. The enlarged side view of the main part in the double structure container of FIG. FIG. 2 is a schematic side sectional view showing a preform for an outer container (4a), a preform for an inner bag container (4b), and a stack preform (4c) used for molding the double-structured container of FIG.

With reference to FIGS. 1 to 3, the double-structured container of the present invention is shown by 30 as a whole, and is composed of an outer container 10 and an inner bag container 20 housed inside the outer container 10. ing.

In FIG. 1, the outer container 10 is formed of a container mouth portion 11 which is a non-stretched portion, and a shoulder portion 12, a body portion 13, and a bottom portion 14, which are shaped by blow stretching, respectively.
The shoulder portion 12 is a portion connected to the lower end of the container mouth portion 11 and has a diameter increasing as it goes downward, and the body portion 13 is a tubular portion connected to the shoulder portion 12 above, and the lower end thereof. Is closed by the bottom 14.
In FIG. 1, the body portion 13 has a straight body shape, but in reality, the central portion thereof is recessed so that a squeeze operation can be easily performed.

The mouth portion 11 of the outer container 10 is a non-crystallized portion, and therefore, the mouth portion 11 may be hereinafter referred to as an amorphous mouth portion. An air introduction port 15 is formed on the outer surface of the non-crystallization port portion 11, and a ring-shaped protrusion 16 at which the lower end of the cap abuts below the air introduction port 15 to prevent air leakage, and further below. Is formed with a support ring 17 used for carrying a preform or a bottle and for receiving a load when attaching a plug cap. Further, when the cap is a screw type instead of a plug type, a screw (not shown) is formed above the ring-shaped protrusion 16.

On the other hand, the inner bag container 20 has a container mouth portion 21 (a portion shown by hatching in FIGS. 1 and 2) which is a non-stretched portion and a bag-shaped portion 23 (usually the thickness thereof) which has been thinned by blow stretching. It is 200 μm or less). Immediately after molding, the bag-shaped portion 23 is in close contact with the inner surfaces of the body portion 13 and the bottom portion from the lower portion of the shoulder portion 12 of the outer container 10 described above.

The mouth portion 21 of the inner bag container 20 is a crystallized portion, and therefore may be hereinafter referred to as a crystallized mouth portion.
As can be understood from FIG. 1, the inner bag container 20 is inserted into the outer container 10, and the crystallization port 21 thereof is larger than the air introduction port 15 in the non-crystallization port 21 of the outer container 10. It is fitted and fixed in the upper part. Further, a peripheral protrusion 25 serving as a stopper is provided at the upper end of the crystallization port 21, and is designed so that the inner bag container 20 does not penetrate deeply into the outer container 10.

In the double-structured container 30 of the present invention, as described above, the mouth portion 21 of the inner bag container 20 is a crystallized mouth portion, and at the same time, the mouth portion 11 of the outer container 10 is a crystallized mouth portion. It is a non-crystallized opening that has not been crystallized.
That is, the mouth portion (crystallization mouth portion) 21 of the inner bag container 20 has excellent heat resistance, and thermal deformation during heating during blow molding is effectively prevented. Further, thermal deformation when the contents are hot-filled in the inner bag container 20 (bag-shaped portion 22) is effectively prevented.
On the other hand, the mouth portion (amorphous mouth portion) 11 of the outer container 10 is rich in flexibility and excellent in impact resistance. For example, when a drop impact is applied to the double-structured container 30, stress concentration in the vicinity of the air introduction port 15 of the non-crystallizing port of the outer container 10 is effectively alleviated, whereby the air introduction port 15 of the outer container 10 is effectively relaxed. It is possible to effectively avoid the occurrence of cracks from the vicinity.

Further, the mouth portion 21 of the inner bag container 20 is increased in rigidity by crystallization, and at the same time, the mouth portion 11 of the outer container 10 is not crystallized and is a highly flexible portion. The fitability between the mouth portion 21 of the inner bag container 20 and the mouth portion 11 of the outer container 10 is improved, and as a result, the mouth portion 21 of the inner bag container 20 can be firmly held without rattling. Further, by such improvement of the fitting property, high adhesion is ensured between the fitting portion between the mouth portion 21 of the inner bag container 20 and the mouth portion 11 of the outer container 10, and therefore, other than the air introduction port 15. It is possible to effectively prevent the leakage of air from the portion of the inner bag 20 and effectively discharge the inner bag 20 from the bag-shaped portion 23 by the squeeze operation.

In the double-structured container 30 of the present invention described above, as is clearly shown in FIG. 2, the inner surface of the non-crystallization port 11 of the outer container 10 and the crystallization port 21 of the inner bag container 20 It is preferable that a gap 27 communicating with the air introduction port 15 is formed between the outer surface and the outer surface.
Such a gap 27 is formed over the entire circumference between the ports 11 and 21 so as to communicate with the air introduction port 15, whereby the air after the contents are discharged by the squeeze operation. Air can be smoothly introduced from the introduction port 15 and peeled from the inner surface of the outer container 10 of the bag-shaped portion 23 of the inner bag container 20, and at the same time, an air layer can be easily formed between the two. It is possible to effectively avoid thermal deformation of the outer surface of the outer container 10 due to heating during blow molding, particularly thermal deformation of the ring-shaped protrusion 16 and the support ring 17.
That is, in blow molding, not only the heating is performed from the outside of the preform using a heater or the like, but also the inside of the preform is positively heated by using a heated iron core or the like. In order to reduce the thickness of the inner bag, the resin forming the inner bag container 20 is heated to a temperature as high as possible in the range of the glass transition point or more and less than the melting point. When the contact area between the inner bag container 20 and the outer surface of the crystallization opening portion 21 is large, the outer surface of the non-crystallization opening portion 11 of the outer container 10 is thermally deformed, and in some cases, it is partially crystallized or due to heat. The relaxation of strain may cause dimensional changes. However, by providing the void 27 as described above, the void 27 becomes a heat insulating layer, and thermal deformation of the outer surface of the amorphous opening portion 11 can be effectively avoided.

In the present invention, the above-mentioned outer container 10 is formed of a blow-moldable thermoplastic resin, and examples of such a thermoplastic resin include the following.
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, 4-methyl-1-pentene. Random or block copolymers of each other, cyclic olefin copolymers, etc .;
Ethylene-vinyl-based copolymers, for example, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, ethylene-vinyl chloride copolymers, etc.;
Styrene-based resins such as polystyrene, acrylonitrile / styrene copolymer, ABS, α-methylstyrene / styrene copolymer, etc.;
Vinyl-based resins such as polyvinyl chloride, polyvinylidene chloride, vinyl chloride / vinylidene chloride copolymer, methyl polyacrylic acid, methyl polymethacrylate, 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 copolymerized polyesters thereof and the like;
Polycarbonate resin;
Polyphenylene oxide resin;
Biodegradable resins such as polylactic acid;
Of course, a blend of these thermoplastic resins can also be used as long as the moldability is not impaired.

Further, since the double-structured container 30 has a structure in which air flows between the outer container 1 and the inner bag container 3, the outer container 10 does not necessarily have to have moisture and gas barrier properties. Polylactic acid having low water and gas barrier properties can also be suitably used for forming the outer container 10. Further, since high barrier properties are not required, it is not necessary to dare to form an intermediate layer made of a gas barrier resin such as ethylene / vinyl alcohol resin.
However, in the present invention, the thermoplastic resin preferably used is polyester in that when the body portion 13 of the outer container 10 is squeezed and dented, the strength that can quickly return to the original shape can be secured. Resin, especially PET.

Further, the inner bag container 20 is formed of a blow-moldable thermoplastic resin like the outer container 1.
In the double-structured container 30, since it is necessary to form an air layer between the bag-shaped portion 23 of the inner bag container 20 and the body portion 13 of the outer container 10 when discharging the contents, the inner bag is usually used. As the thermoplastic resin for forming the container 20, a resin that can be quickly peeled off from the outer container 10 is preferably used. For example, by blending a slip agent such as liquid paraffin, an inner bag is used. It does not matter if the thermoplastic resin forming the container 20 is of the same type as the thermoplastic resin forming the outer container 10, and in particular, since it is easy to set the blow stretching conditions, the inner bag container 20 is formed. It is preferable that the thermoplastic resin for use and the thermoplastic resin forming the outer container 10 are of the same type, and for example, it is optimal that the inner bag container 20 is also made of a polyester resin such as PET.

In the double-structured container 30 of the present invention, since the mouth portion 11 of the outer container 10 is not crystallized and the mouth portion 21 of the inner bag container 20 is crystallized, the stack preform method or preform -Manufactured by the in-bottle method.

The above stack preform method is performed by injection molding using a first preform (preform for outer container) obtained by injection molding using a resin for an outer container and a resin for an inner bag container. Using the obtained second preform (preform for inner bag container), the second preform is inserted into the first preform to form a multi-structured stack preform, and this stack preform is formed. It is a method of performing biaxial stretch blow molding.

In FIG. 4 for explaining the above stacking method, the stack preform for molding the double-structured container 30 of FIGS. 1 to 3 is shown by 50 as a whole (see FIG. 4 (c)). Both are formed from a first preform 51 (see FIG. 4 (a)) and a second preform 53 (see FIG. 4 (b)) having a test tube shape.
That is, the first preform 51 is a preform for molding the outer container, the second preform 53 is the preform for molding the inner bag container, and the second preform 53 is inserted into the first preform. By fitting and holding the stack preform 50 to be subjected to the blow stretching step, the stack preform 50 is assembled.

As can be understood from FIG. 4, the first preform 51 and the second preform 53 both have the mouth portion 11 (non-crystallized mouth portion) of the outer container 10 and the mouth portion 21 of the inner bag container 20 (the mouth portion 21 (non-crystallized mouth portion)). It has a portion corresponding to the crystallization port). That is, none of these portions are stretch-molded portions, and the mouth portion 11 of the first preform 51 is a ring-shaped protrusion 16, a support ring 17, and an air introduction port formed during injection molding or post-processing. The second preform 53 has a peripheral protrusion 25 as a stopper at the upper end of the mouth portion 21 of the second preform 53.
Further, the tubular portion 51a in which the lower end of the lower portion of the mouth portion 11 of the first preform 51 is closed is stretch-molded, and the shoulder portion 12, the body portion 13, and the body portion 13 of the outer container 10 are stretched by blow stretching. It is shaped in the form of the bottom 14.
Further, the tubular portion 53a in which the lower end of the lower portion of the mouth portion 21 of the second preform 53 is closed is stretch-molded, and the inner bag container 20 is formed into the bag-shaped portion 23 by blow stretching. It is shaped.
The lower portion of the mouth portion 21 of the second preform 53 has a reduced diameter in order to form a gap 27 as shown in FIG. 2 when inserted into the first preform 51. It is in the form of

The first preform 51 and the second preform 53 are both molded by injection molding using a resin for forming an outer container or a resin for forming an inner bag container, but the second preform is formed. The mouth portion 21 of 53 is crystallized by heating after molding, and is crystallized so that the degree of crystallization by, for example, a density method is 20% or more, more preferably 30% or more.

By inserting the second preform 53 into the first preform 51, the stack preform 50 having the form shown in FIG. 4 (c) is assembled, placed in a blow mold, and a predetermined jig is used. The first preform 51 and the second preform 53 can be stretch-molded by fixing the portion including the mouth portions 11 and 21 with an iron core heated by an infrared heater, high-frequency heating, or the like. It is heated to (above the glass transition point temperature of the resin forming the preform and below the melting point), and a stretch rod (not shown) is inserted into the stack preform 50 (second preform 53). By stretching in the uniaxial direction, further supplying a blow fluid such as air, and expanding in the circumferential direction, the double-structured container 30 having the form shown in FIGS. 1 to 3 can be obtained. That is, as the tubular portion 53a of the second preform 53 expands, the tubular portion 51a of the first preform 51 is expanded and expanded, and each of them is shaped into the shape of a container. ..

In the present invention, as described above, the mouth portion 21 of the second preform 53 (preform for forming the inner bag container 20) is crystallized to impart heat resistance and rigidity. The mouth portion 11 of the first preform 51 (preform for forming the outer container 10) is not crystallized and is therefore highly flexible. Therefore, as shown in FIG. 4C, when the second preform 53 is inserted into the first preform 51, the amorphous mouth portion 11 (non-crystallized mouth portion) and the crystalline mouth portion 11 are formed. The fitability with the mouth portion 21 (crystallized mouth portion) is high, the adhesion with these mouth portions 11 and 21 can be ensured, and the second preform 21 can be firmly held without rattling. can. Therefore, stretch blow molding using the stack preform 50 assembled by the first preform 51 and the second preform 53 can be stably performed without causing molding defects.

Further, in the stretch blow molding, since the void 27 is formed between the crystallized mouth portion 21 and the non-crystallized mouth portion 11, this void functions as a heat insulating layer and is heated to a high temperature. The heat transfer from the mouth portion 21 to the mouth portion 11 is effectively suppressed. Therefore, by this stretch blow molding, the thermal deformation of the uncrystallized mouth portion 11, particularly the thermal deformation of the portion in the vicinity of the air introduction port 15, or the thermal deformation of the ring-shaped protrusion 16 and the support ring 17 is effectively suppressed. ..

Although the stack preform method has been described in FIG. 4, the preform-in-bottle method is basically the same, and the above-mentioned advantages of the present invention can be enjoyed.
That is, in the preform-in-bottle method, the outer container 10 having the uncrystallized mouth portion 11 is preformed by stretch blow molding completely separate from the inner bag container 20. A second preform 53 having the crystallized mouth portion 21 described above is inserted into the outer container 10 thus formed, and a stretch rod is inserted and a blow fluid is inserted into the second preform 53. By performing biaxial stretch blow molding by supplying the above, the double-structured container 30 having the form shown in FIGS. 1 to 3 can be obtained. In this case, the outer container 10 functions as a molding mold for blow molding the inner bag container 20.

In the above-mentioned invention, various as long as the feature of the present invention that the mouth portion 11 of the outer container 10 is not crystallized and only the mouth portion 21 of the inner bag container 20 is crystallized is not impaired. It is possible to change the design of.
For example, in the examples of FIGS. 1 to 3, a peripheral protrusion 25 serving as a stopper is provided at the upper end of the mouth 21 of the inner bag container 20, but the mouth 21 is extended above the peripheral protrusion 25. , A screw for attaching a cap can be provided in the extended portion. In this case, the ring-shaped protrusion 16 is not provided on the outer peripheral surface of the mouth portion 11 of the outer container 10, and only the support ring 17 is provided.

The double-structured container 10 of the present invention manufactured as described above has the contents contained in the bag-shaped portion 23 of the inner bag container 20, and then has the reverse known to itself in the mouth portion 11 of the outer container 10. It is used with a cap with a check valve attached.

In such a double-structured container 10 of the present invention, the contents filled in the inner bag container 20 (bag-shaped portion 23) are pressed by, for example, squeezing (pressing) the body portion 13 of the outer container 10. The contents are discharged one by one, and the contents are discharged, and the volume of the bag-shaped portion 23 of the inner bag container 20 is reduced. Since air is introduced between the container 10 and the inner surface of the body portion 13 to form an air layer, the subsequent contents can be effectively discharged.

10: Outer container 11: Outer container mouth (amorphous mouth)
13: Body of outer container 15: Air inlet 16: Ring-shaped protrusion 17: Support ring 20: Inner bag container 21: Mouth of inner bag container (crystallization port)
23: Bag-shaped part 25: Circumferential protrusion 27: Void 30: Double-structured container 50: Stack preform 51: First preform (preform for forming an outer container)
53: Second preform (preform for forming an inner bag container)

Claims (4)

A double container consisting of an outer container and an inner bag container inserted and held in the outer container, and provided with an air introduction port for introducing air between the inner surface of the outer container and the outer surface of the inner bag container. In a structural container
The outer container includes a non-crystallized opening portion which is a non-stretched portion, and a body portion and a bottom portion which are stretched portions.
The inner bag container includes a crystallization port portion which is a non-stretched portion and a bag-shaped portion which is a stretched portion, and the crystallization port portion is fitted and fixed to the non-crystallization port portion of the outer container. A double-structured container characterized by that. The double-structured container according to claim 1, wherein a gap is formed between the inner surface of the non-crystallization port portion of the outer container and the outer surface of the crystallization port portion of the inner bag container. The double-structured container according to claim 1 or 2, wherein the air introduction port is formed in the amorphous port portion of the outer container. The double-structured container according to claim 1 to 3, wherein the void communicates with the air inlet.

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