JP7279398B2 - multiple container - Google Patents

Description

The present invention relates to multiple containers.

A multi-layered container is known in which a space is formed between an inner container and an outer container that are peelably laminated to achieve a heat-retaining function for the contents (for example, Patent Document 1).

JP 2005-47172 A

In the multiple container described in Patent Document 1, the outer container is molded using a synthetic resin selected from polypropylene resins and cyclic polyolefin resins, and the inner container is molded using polyethylene terephthalate resin. For this reason, the multiple container described in Patent Document 1 complicates the molding process and increases the cost of the resin material. Furthermore, in the multiple container described in Patent Document 1, it is necessary to separate the inner container and the outer container after use, and to treat the inner container and the outer container in different recycling processes. Furthermore, the multiple container described in Patent Document 1 has room for improvement in stably forming a gap large enough to realize the function of keeping the contents warm.

The present invention has been made in view of the circumstances described above, and an object thereof is to solve the problems described above. That is, one example of the object of the present invention is to provide a multi-layer container which has a function of keeping contents warm and which can be easily realized with high recycling efficiency.

A multiple container according to the present invention is a multiple container in which an inner container and an outer container enclosing the inner container are detachably laminated, and the outer container and the inner container are homogenized in a blow mold. A preform corresponding to the outer container made of a polymer polyester resin and a preform corresponding to the inner container made of a copolymer polyester resin are biaxially stretched and blown to form a bottle shape . The inner container has a lower heat shrink temperature than the outer container, which indicates the temperature at which heat shrink starts later.

Preferably, in the multiple container, the heat shrinkage temperature of the outer container is 90°C or higher and 95°C or lower in thermomechanical analysis, and the heat shrinkage temperature of the inner container is 85°C or lower in thermomechanical analysis.

Preferably, in the multiple container, the heat shrinkage rate of the outer container is 3% or less, where the rate of change in the volume of each of the outer container and the inner container due to heat shrinkage after molding is defined as the heat shrinkage rate. and the thermal contraction rate of the inner container is 10% or more and 40% or less.

Preferably, in the multiple container, the intrinsic viscosity of the resin forming the inner container is higher than the intrinsic viscosity of the resin forming the outer container.

Preferably, in the multiple container, the intrinsic viscosity of the resin forming the inner container is 0.75 or more and 0.85 or less, and the intrinsic viscosity of the resin forming the outer container is 0.65 or more and 0.65 or more. 75 or less.

Preferably, in the multiple container, the crystallinity of the inner container is lower than the crystallinity of the outer container.

Preferably, in the multiple container, the crystallinity of the outer container is 25% or more and 40% or less, and the crystallinity of the inner container is at least 5% lower than the crystallinity of the outer container.

Preferably, the multiple container further comprises an outside air introduction hole through which outside air can be introduced between the outer container and the inner container.

Preferably, in the multiple container , the length of the axially outer surface side of the preform extending portion corresponding to the inner container is the length of the axial inner surface side of the preform extending portion corresponding to the outer container. The length is 0.5 to 0.8 times the length.

INDUSTRIAL APPLICABILITY The multiple container according to the present invention can easily realize a container having a function of keeping contents warm and having high recycling efficiency.

1 is a diagram schematically showing a longitudinal section of a multiple container according to Embodiment 1. FIG. 4A and 4B are diagrams showing various characteristics of the outer container and the inner container according to Embodiment 1. FIG. FIG. 4 is a diagram showing characteristics related to heat shrinkage of the outer container and the inner container according to Embodiment 1; FIG. 10 is a diagram schematically showing a longitudinal section of a multiple container according to Embodiment 2; FIG. 10 is a diagram schematically showing a preform for manufacturing a multiple container according to Embodiment 3;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In this embodiment, the direction along the central axis Z of the bottle-shaped multiple container 1 is also referred to as the "axial direction", and the direction in which the multiple container 1 revolves around the central axis Z as the rotation axis is also referred to as the "circumferential direction". The direction orthogonal to the central axis Z of the multiple container 1 is also called "radial direction". In this embodiment, the axial direction from the mouth 3 to the bottom 6 of the multiple container 1 is also called "downward", and the axial direction from the bottom 6 to the mouth 3 of the multiple container 1 is also called "upward". Further, in the present embodiment, a cross section obtained by cutting the multiple container 1 along the central axis Z of the multiple container 1 is also referred to as a "longitudinal section", and the multiple container 1 is cut along a plane perpendicular to the central axis Z of the multiple container 1. A cut cross section is also referred to as a "cross section".

[Embodiment 1]
FIG. 1 is a diagram schematically showing a longitudinal section of a multiple container 1 according to Embodiment 1. FIG. The multiple container 1 shown in FIG. 1 shows a state after the inner surface of the outer container 10 and the outer surface of the inner container 20 are peeled off, like the state after the content is filled.

The multiple container 1 is a bottle-shaped container. As shown in FIG. 1, the multiple container 1 has a mouth portion 3 which is one end of the multiple container 1 and has an outlet 21 for pouring out the contents, and a bottom portion 6 which is the other end of the multiple container 1 and has a ground portion. , a shoulder portion 4 extending downward from a mouth portion 3 while expanding radially outward, and a body portion 5 extending downward from the shoulder portion 4 and continuing to a bottom portion 6 .

The multiple container 1 comprises a bottle-shaped outer container 10 that constitutes the outer shell of the multiple container 1 and contains an inner container 20, and an inner container 20 that accommodates the contents and has a shape along the inner surface of the outer container 10. Prepare. The multiple container 1 is a heat insulating bottle in which the inner surface of the outer container 10 and the outer surface of the inner container 20 are laminated so as to be peelable. The contents of the multiple container 1 may be high-temperature contents such as hot beverages, or low-temperature contents such as cold beverages or frozen desserts.

The outer container 10 and the inner container 20 are containers made of synthetic resin and manufactured by blow molding. Preferably, the outer container 10 and the inner container 20 are manufactured by biaxial stretch blow molding using tubular preforms such as test tube shapes. Specifically, the outer container 10 and the inner container 20 are formed by inserting the preform of the inner container 20 into the preform of the outer container 10 and stacking the preform of the outer container 10 and the preform of the inner container 20 . It is manufactured by simultaneously stretch-blow-molding the foam and the foam. Alternatively, the outer container 10 and the inner container 20 may be manufactured by stretch blow molding the preform of the outer container 10 and then stretch blow molding the preform of the inner container 20 inside the outer container 10 . Alternatively, the outer container 10 and the inner container 20 may be manufactured by molding a multilayered preform by so-called coinjection molding or overmolding, and then subjecting the multilayered preform to stretch blow molding.

The outer container 10 and the inner container 20 are made of polyolefin resin, ethylene-vinyl copolymer, styrene resin, vinyl resin, polyamide resin, polyester resin, polycarbonate resin, polyphenylene oxide resin, or raw material. Molded using a decomposable resin. Preferably, the outer container 10 and the inner container 20 are molded using polyolefin resin or polyester resin. More preferably, the outer container 10 and the inner container 20 are molded using a polyester-based resin. Examples of the polyester-based resin include resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and copolyester thereof. Particularly preferably, the outer container 10 and the inner container 20 are molded using polyethylene terephthalate resin.

In the blow molding process of the multiple container 1, the preform in the heated blow mold is stretched with a stretch rod, blown with blow air, pressed against the blow mold, and cooled with air. An outer container 10 and an inner container 20 having corresponding shapes are molded. In this process, each of the outer container 10 and the inner container 20 is distorted due to stretching or the like. Although this distortion is relieved by heat setting by the blow mold, it is not completely removed and remains in the outer container 10 and the inner container 20 after molding.

Therefore, when the multi-layered container 1 is heated after molding, the residual strain existing in the outer container 10 and the inner container 20 is relaxed, and heat shrinkage occurs. In particular, in the multi-layer container 1, heat sterilization of the container and hot filling in which the contents are heated to a high temperature are performed in the process of filling the contents after molding. Alternatively, in the multiple container 1, heat treatment is performed after molding and before the filling process. For this reason, the multiple container 1 is heated after molding, and thermal shrinkage occurs.

The thermal shrinkage of the inner container 20 after molding of the multiple container 1 tends to be greater than that of the outer container 10 . This is because the inner container 20 may have a larger residual strain than the outer container 10 . The reason why the residual strain of the inner container 20 is larger than that of the outer container 10 is that the draw ratio of the inner container 20 is higher than that of the outer container 10 . Also, as a factor for this, when the residual strain is relieved by heat setting, the outer container 10 is in contact with the blow mold, but the inner container 20 is not in contact with the blow mold. For example, the strain relaxation effect is smaller than that of the outer container 10 . Furthermore, as a factor for this, since cooling air is blown into the inner container 20 , the effect of alleviating residual strain is smaller than that of the outer container 10 .

When the amount of heat shrinkage of the inner container 20 is greater than that of the outer container 10, the outer surface of the inner container 20, which is in close contact with the inner surface of the outer container 10, separates from the inner surface of the outer container 10 in the multiple container 1, and the outer container 10 and the outer container 10 are separated from each other. A gap A can be formed between the inner container 20 and the inner container 20 . That is, the space A is a space formed between the outer container 10 and the inner container 20 by separating the outer container 10 and the inner container 20 from each other. Since the mouth portion 3 is a non-stretched portion that is not stretched and the bottom portion 6 can be configured so as not to be peeled off, the gap A is formed at least between the body portion 5 of the inner container 20 and the body portion 5 of the outer container 10 after molding. It may be a space formed by peeling due to heat shrinkage.

In the multiple container 1, if the radial length of the space A is sufficiently large, the space A can sufficiently exhibit a heat insulation effect and maintain the temperature of the contents, so that the taste of the contents can be maintained. can be done. However, in a normal multi-layered container, there is no large difference between the amount of heat shrinkage of the outer container and the amount of heat shrinkage of the inner container due to heat shrinkage after molding, and a gap A large enough to sufficiently exhibit a heat insulating effect is formed. hard. In particular, when the outer container and the inner container are molded using the same type of resin, the compatibility between the outer container and the inner container increases, making it difficult for the outer container and the inner container to separate. Void A is difficult to form. On the other hand, if the outer container and the inner container are molded using different resins, it is necessary to separate the outer container from the inner container after use. costs may increase.

Therefore, the multiple container 1 is molded using the same type of resin, has heat resistance that can be applied to hot filling, and has a large gap A that can sufficiently exhibit a heat insulating effect. Formed by thermal shrinkage after molding. The outer container 10 and the inner container 20 are configured as shown in FIG.

FIG. 2 is a diagram showing various characteristics of the outer container 10 and the inner container 20 according to Embodiment 1. FIG. FIG. 3 is a diagram showing the characteristics of heat shrinkage of the outer container 10 and the inner container 20 according to the first embodiment.

FIG. 3 shows how the length of the test piece changes in the process of heating the test piece taken out from the molded outer container 10 or the inner container 20 to raise the temperature of the test piece. The vertical axis in FIG. 3 indicates the length of the test piece when the length before heating is taken as 100%, and the horizontal axis in FIG. 3 indicates the temperature.

In the multiple container 1, as shown in FIG. 2, the intrinsic viscosity (IV) of the resin forming the inner container 20 is higher than the intrinsic viscosity of the resin forming the outer container 10. . Preferably, the multiple container 1 is configured such that the difference value obtained by subtracting the intrinsic viscosity of the resin composing the outer container 10 from the intrinsic viscosity of the resin composing the inner container 20 is 0.01 or more. The intrinsic viscosity of a resin correlates with the molecular weight of the resin. Resins with low intrinsic viscosities are often low molecular weight resins, and resins with high intrinsic viscosities are often high molecular weight resins. Since the inner container 20, which is molded from a resin having a relatively high intrinsic viscosity, has relatively long molecular chains, the molecular chains are likely to be entangled during stretching in blow molding, and many of the molecular chains are likely to remain entangled and harden, resulting in residual strain. tends to grow. For this reason, when the inner container 20 is heated after molding, the residual strain is relieved relatively greatly, so the amount of heat shrinkage increases. On the other hand, the outer container 10 molded from a resin having a relatively low intrinsic viscosity has a relatively short molecular chain, so the molecular chain is less likely to become entangled during stretching in blow molding, and the residual strain is relatively small. For this reason, the outer container 10 is less relaxed in residual strain than the inner container 20 , so the amount of heat shrinkage is smaller than that of the inner container 20 . As a result, in the multiple container 1, as shown in FIG. 3, a clear difference can be provided between the amount of heat shrinkage of the outer container 10 and the amount of heat shrinkage of the inner container 20 due to heat shrinkage after molding. It is possible to stably form a gap A large enough to sufficiently exhibit the effect.

In particular, the multiple container 1 is configured such that the intrinsic viscosity of the outer container 10 is 0.65 or more and 0.75 or less, and the intrinsic viscosity of the inner container 20 is 0.75 or more and 0.85 or less. As a result, the resin constituting the outer container 10 can have an intrinsic viscosity equivalent to that of polyethylene terephthalate resin constituting a so-called heat-resistant PET bottle. Furthermore, the resin forming the inner container 20 can have an intrinsic viscosity equivalent to that of polyethylene terephthalate resin forming general non-heat-resistant PET bottles. In the multiple container 1, as shown in FIG. 3, a significant difference can be provided between the amount of heat shrinkage of the outer container 10 and the amount of heat shrinkage of the inner container 20 due to heat shrinkage after molding, resulting in a larger gap. A can be formed more stably.

Further, in the multiple container 1, the crystallinity of the inner container 20 is lower than that of the outer container 10, as shown in FIG. Specifically, in the multiple container 1 , the crystallinity of the body portion 5 of the inner container 20 may be lower than the crystallinity of the body portion 5 of the outer container 10 . This is because, in the multiple container 1 , the mouth portion 3 is a non-stretched portion, the bottom portion 6 can be constructed so as not to be peeled off, and most of the storage space S is located in the trunk portion 5 . The outer container 10 and the inner container 20 are molded using a crystalline resin in which a crystalline portion and an amorphous portion are mixed. The degree of crystallinity indicates the ratio of the crystalline part to the total volume including the crystalline part and the non-crystalline part. Since the crystal part is a part where the molecular chains are relatively regularly aligned and solidified, the binding force of the molecular chains is strong, and a large amount of heat is required to soften the molecular chains so that they can move easily. Therefore, in the outer container 10 with a high degree of crystallinity, the molecular chains do not easily move unless the temperature is relatively high, so that the heat resistance is increased and the temperature at which the residual strain is relaxed and thermal contraction starts is increased. . On the other hand, in the inner container 20 with a low degree of crystallinity, the molecular chains are more likely to move at a temperature lower than that of the outer container 10, so the heat resistance is lower than that of the outer container 10, and the residual strain is relaxed to start thermal contraction. the temperature applied is lower. As a result, in the multiple container 1, as shown in FIG. 3, a clear difference can be provided between the amount of heat shrinkage of the outer container 10 and the amount of heat shrinkage of the inner container 20 due to heat shrinkage after molding. It is possible to stably form a gap A large enough to sufficiently exhibit the effect.

In particular, the multiple container 1 is configured such that the crystallinity of the outer container 10 is 25% or more and 40% or less, and the crystallinity of the inner container 20 is lower than that of the outer container 10 by at least 5%. As a result, the outer container 10 can have heat resistance and heat shrinkage equivalent to those of a so-called heat-resistant PET bottle. Furthermore, the inner container 20 can have heat resistance and heat shrinkage equivalent to those of general PET bottles that are not heat resistant. In the multiple container 1, as shown in FIG. 3, a significant difference can be provided between the amount of heat shrinkage of the outer container 10 and the amount of heat shrinkage of the inner container 20 due to heat shrinkage after molding, resulting in a larger gap. A can be formed more stably.

In the multiple container 1, as shown in FIG. 2, the inner container 20 has a lower heat shrinkage temperature than the outer container 10, which indicates the temperature at which heat shrinkage starts after molding. The heat shrinkage temperature is the length of the test piece taken out from the outer container 10 or the inner container 20 after molding, and the length of the test piece becomes 99.5% of the length before heating. It can be temperature. When the heat shrinkage temperature is low, the timing at which the residual strain begins to be relaxed in the temperature rising process is earlier. Therefore, in the inner container 20 having a low heat shrinkage temperature, the residual strain is relaxed relatively greatly for a certain period of time, and the amount of heat shrinkage increases. On the other hand, in the outer container 10 having a high heat shrinkage temperature, the residual strain is not relaxed as much as in the inner container 20, so the amount of heat shrinkage is smaller than that in the inner container 20. As a result, in the multiple container 1, as shown in FIG. 3, a clear difference can be provided between the amount of heat shrinkage of the outer container 10 and the amount of heat shrinkage of the inner container 20 due to heat shrinkage after molding. It is possible to stably form a gap A large enough to sufficiently exhibit the effect.

In particular, in the multiple container 1, the heat shrinkage temperature of the outer container 10 is 90° C. or more and 95° C. or less in thermal mechanical analysis (TMA), and the heat shrinkage temperature of the inner container 20 is 85° C. or less in thermomechanical analysis. configured as However, the heat shrink temperature is a temperature equal to or higher than the glass transition temperature. Therefore, the heat shrinkage temperature of the inner container 20 may be equal to or higher than the glass transition temperature of the resin used for molding the inner container 20 and equal to or lower than 85°C. As a result, the outer container 10 can have heat resistance and heat shrinkage equivalent to those of a so-called heat-resistant PET bottle. Furthermore, the inner container 20 can have heat resistance and heat shrinkage equivalent to those of general PET bottles that are not heat resistant. In the multiple container 1, as shown in FIG. 3, a significant difference can be provided between the amount of heat shrinkage of the outer container 10 and the amount of heat shrinkage of the inner container 20 due to heat shrinkage after molding, resulting in a larger gap. A can be formed more stably.

Further, in the multiple container 1, as shown in FIG. 2, the inner container 20 is formed using a copolymer polyester resin, and the outer container 10 is formed using a homopolymer polyester resin. be. Preferably, in the multiple container 1, the inner container 20 is molded using a copolymer polyethylene terephthalate resin and the outer container 10 is molded using a homopolymer polyethylene terephthalate resin. Polyethylene terephthalate resin is a polyester resin produced by condensation polymerization of ethylene glycol and terephthalic acid. Homopolymeric polyethylene terephthalate resins start with only ethylene glycol and terephthalic acid. Copolymer polyethylene terephthalate resins start not only with ethylene glycol and terephthalic acid, but also with other chemicals such as isophthalic acid.

Since the homopolymer polyethylene terephthalate resin is composed of one type of monomer, the molecular chains are densely aggregated and the degree of crystallinity tends to be high. Copolymer polyethylene terephthalate resins tend to have lower crystallinity than homopolymers because they consist of two or more monomers. For this reason, the outer container 10 molded using a homopolymer polyester resin has relatively high heat resistance and a relatively high heat shrinkage temperature. On the other hand, the inner container 20 molded using a copolymer polyester resin has a lower heat resistance than the outer container 10 and a lower heat shrink temperature than the outer container 10 . As a result, in the multiple container 1, as shown in FIG. 3, a clear difference can be provided between the amount of heat shrinkage of the outer container 10 and the amount of heat shrinkage of the inner container 20 due to heat shrinkage after molding. It is possible to stably form a gap A large enough to sufficiently exhibit the effect.

Further, in the multiple container 1, as shown in FIG. 2, the heat shrinkage rate of the outer container 10 is 3% or less, and the heat shrinkage rate of the inner container 20 is 10% or more and 40% or less. . This thermal shrinkage rate is the rate of change in the volume of each of the outer container 10 and the inner container 20 due to thermal shrinkage after molding. This thermal shrinkage rate may be the volume change rate of the outer container 10 and the inner container 20 when they are thermally shrunk by filling the contents at 90° C. for 3 minutes. As a result, in the multiple container 1, as shown in FIG. 3, a significant difference can be provided between the amount of heat shrinkage of the outer container 10 and the amount of heat shrinkage of the inner container 20 due to heat shrinkage after molding. The gap A can be formed more stably.

In the multiple container 1, the outer container 10 and the inner container 20 do not need to have all of the characteristics shown in FIG. 2, but only some of the characteristics shown in FIG. may be For example, in the multiple container 1, the outer container 10 and the inner container 20 may have only the characteristic of "intrinsic viscosity" shown in FIG.

As described above, in the multiple container 1 according to Embodiment 1, the outer container 10 and the inner container 20 are molded using the same kind of resin and configured to have the characteristics shown in FIG. Therefore, the multiple container 1 according to Embodiment 1 has heat resistance applicable to hot filling, and can stably form large gaps A that can sufficiently exhibit a heat insulating effect. Moreover, in the multiple container 1 according to Embodiment 1, the outer container 10 and the inner container 20 are molded using polyester resin, preferably polyethylene terephthalate resin. That is, in the multiple container 1 according to Embodiment 1, the outer container 10 and the inner container 20 are molded using an existing molding method called biaxial stretch blow molding using a resin that has high gas barrier properties and is inexpensive and easily available. be done. In addition, in the multiple container 1 according to Embodiment 1, there is no need to separate the outer container 10 and the inner container 20 after use, and they can be treated collectively in the existing recycling process.

As a result, in the multiple container 1 according to Embodiment 1, the efficiency of recycling is high, and the heat insulation effect is sufficiently achieved while suppressing the complication of the molding process and the increase in the cost of the resin material. It is possible to stably form a gap A large enough to be effective. Therefore, the multiple container 1 according to Embodiment 1 can easily realize a container having a function of keeping contents warm and having high recycling efficiency, and can maintain the taste of the contents.

[Other embodiments]
The multiple container 1 according to Embodiments 2 and 3 will be described. In the description of the multiple container 1 according to Embodiments 2 and 3, the description of the configuration and operation similar to those of the multiple container 1 according to Embodiment 1 will be redundant and will be omitted.

FIG. 4 is a diagram schematically showing a longitudinal section of the multiple container 1 according to Embodiment 2. As shown in FIG. The multiple container 1 shown in FIG. 4 shows a state after the inner surface of the outer container 10 and the outer surface of the inner container 20 are peeled off, like the state after the content is filled.

The multiple container 1 according to Embodiment 2 further includes an outside air introduction hole 11 through which outside air can be introduced between the outer container 10 and the inner container 20 . Specifically, the outside air introduction hole 11 may be provided in the mouth portion 3 of the outer container 10 and communicate with the gap A, as shown in FIG. Alternatively, the outside air introduction hole 11 may be provided as a slit in a portion where the mouth portion 3 of the outer container 10 and the mouth portion 3 of the inner container 20 are fixed.

In the multiplex container 1 according to Embodiment 1, the outer surface of the inner container 20 that was in close contact with the inner surface of the outer container 10 is peeled off from the inner surface of the outer container 10, forming a gap A between the outer container 10 and the inner container 20. Then, the air gap A can be in a near-vacuum state. Since it is difficult to conduct heat in the void A in a state close to vacuum, the multiple container 1 according to the first embodiment can exhibit a high heat insulating effect.

On the other hand, in the multiplex container 1 according to the second embodiment, when the outer surface of the inner container 20 that is in close contact with the inner surface of the outer container 10 separates from the inner surface of the outer container 10, the outer air flows from the outer air introduction hole 11 toward the gap A. be introduced. As a result, in the multiple container 1 according to the second embodiment, the inner container 20 can be easily separated from the outer container 10, so that the gap A can be formed more easily than in the first embodiment.

In addition, in the multiple container 1 according to the second embodiment, outside air is introduced from the outside air introduction hole 11 into the gap A, so that the gap A has a pressure equivalent to the atmospheric pressure. As a result, in the multiplex container 1 according to the second embodiment, the pressure on the outside and the inside of the outer container 10 is approximately the same, so deformation of the outer container 10 is suppressed without increasing the rigidity of the outer container 10. be able to.

FIG. 5 is a diagram schematically showing preforms 100 and 200 for manufacturing the multiple container 1 according to Embodiment 3. FIG.

The multiple container 1 is manufactured by biaxially stretching blow molding a preform 100 corresponding to the outer container 10 and a preform 200 corresponding to the inner container 20 . The preforms 100 and 200 correspond to the mouth portion 3 and correspond to the non-stretched portion M, which is a portion not stretched by biaxial stretch blow molding, and the shoulder portion 4, the body portion 5 and the bottom portion 6, which are subjected to biaxial stretch blow molding. and a stretched portion N, which is a portion stretched by

In the multiple container 1 according to Embodiment 3, the axial length of the stretched portion N of the preform 200 corresponding to the inner container 20 is shorter than the axial length of the stretched portion N of the preform 100 corresponding to the outer container 10. . Preferably, in the multiple container 1 according to Embodiment 4, the length L2 of the axially outer surface side of the stretched portion N of the preform 200 is The length is 0.5 to 0.8 times the length L1 on the inner surface side.

With this configuration, in the multiple container 1 according to Embodiment 3, the draw ratio of the inner container 20 is significantly larger than that of the outer container 10 . There can also be significantly large residual strains. As a result, in the multiple container 1 according to Embodiment 3, a significant difference can be provided between the amount of heat shrinkage of the outer container 10 and the amount of heat shrinkage of the inner container 20 due to heat shrinkage after molding. The gap A can be stably formed.

The length L2 of the preform 200 being 0.5 to 0.8 times as long as the length L1 of the preform 100 means that the large gap A as described above is formed and The length is such that the reform 200 is not excessively stretched and the inner container 20 is not excessively thinned.

[others]
In the above-described embodiment, the multiple container 1 is a heat-insulating bottle that has heat resistance applicable to hot filling and maintains the temperature of the contents by the heat-insulating effect of the void A. However, the multiple container 1 may be a freshness-preserving bottle that stores contents such as liquid seasonings or liquid cosmetics and preserves the freshness of the contents. A freshness-keeping bottle is also called a delaminated bottle, an airless bottle, or the like.

In the multiple container 1, which is a freshness-keeping bottle, the basic configurations of the outer container 10, the inner container 20, and their preforms 100 and 200 are the same as those of the above embodiments. However, the multiple container 1, which is a freshness-preserving bottle, is provided with the outside air introduction hole 11 shown in the second embodiment, and the opening 3 is fitted with a cap with a check valve. In the multiple container 1, which is a freshness-keeping bottle, when the outer container 10 is squeezed, the contents are poured out and the inner container 20 is contracted. , the contracted state of the inner container 20 is maintained. As a result, in the multiple container 1, which is a freshness-preserving bottle, the contraction of the inner container 20 progresses as the contents decrease, and the inflow of outside air from the spout 21 is suppressed, thereby suppressing the oxidation of the contents. It can retain its freshness. In particular, in the multiple container 1, which is a freshness-preserving bottle, the fact that the outer container 10 and the inner container 20 have the characteristics shown in FIG. This is effective because it facilitates peeling of the inner container 20 .

In the above-described embodiment, the multiple container 1 is a container in which the outer container 10 constitutes the outer shell of the multiple container 1 and the inner container 20 contains the contents. However, the multiple container 1 is not limited to a container in which the outer container 10 constitutes the outer shell of the multiple container 1 and the inner container 20 contains the contents. That is, the multiple container 1 may have a container forming the outer shell of the multiple container 1 further outside the outer container 10 or a container containing the contents further inside the inner container 20 . In this way, the multiple container 1 may function as a laminate in which the outer container 10 and the inner container 20 are laminated adjacent to each other in a detachable manner and form a gap A between them. It may be a container having a multi-layered structure of three or more layers capable of forming a plurality of gaps A.

In the above-described embodiment, the multiple container 1 corresponds to an example of the "multiple container" described in the claims. The outer container 10 corresponds to an example of the "outer container" described in the claims. The inner container 20 corresponds to an example of the "inner container" described in the claims. The outside air introduction hole 11 corresponds to an example of the "outside air introduction hole" described in the claims. The preform 100 corresponds to an example of the "preform" corresponding to the "outer container" described in the claims. The preform 200 corresponds to an example of the "preform" corresponding to the "inner container" described in the claims.

The above-described embodiments can apply each other's techniques to each other including the modifications. The above-described embodiments do not limit the content of the present invention, and modifications can be made without departing from the scope of the claims.

The terms used in the above-described embodiments and claims should be interpreted as non-limiting terms. For example, the term "including" should be interpreted as "not limited to what is stated to include." The term "comprising" should be interpreted as "not limited to what is described as comprising". The term "having" should be interpreted as "not limited to what is described as having".

1 Multiple container 3 Mouth 4 Shoulder 5 Body 6 Bottom 10 Outer container 11 Outside air introduction hole 20 Inner container 21 Spout 100 Preform 200 Preform A Gap M Non-stretched portion N Stretched portion S Housing space Z Central axis

Claims (9)

A multiple container in which an inner container and an outer container enclosing the inner container are detachably laminated,
For the outer container and the inner container , a preform corresponding to the outer container made of a homopolymer polyester-based resin and a preform corresponding to the inner container made of a copolymer polyester-based resin are formed in a blow mold . , molded into a bottle shape by biaxially stretch blow molding ,
The heat shrinkage temperature, which indicates the temperature at which heat shrinkage starts after molding, is lower in the inner container than in the outer container.
multiple containers. The heat shrinkage temperature of the outer container is 90° C. or higher and 95° C. or lower in thermomechanical analysis,
The heat shrinkage temperature of the inner container is 85 ° C. or less in thermomechanical analysis,
A multiple container according to claim 1. If the rate of change in the volume of each of the outer container and the inner container due to heat shrinkage after molding is defined as the heat shrinkage rate,
The thermal contraction rate of the outer container is 3% or less,
The heat shrinkage rate of the inner container is 10% or more and 40% or less.
3. A multiple container according to claim 1 or 2. The intrinsic viscosity of the resin constituting the inner container is greater than the intrinsic viscosity of the resin constituting the outer container.
The multiple container according to any one of claims 1-3. The intrinsic viscosity of the resin constituting the inner container is 0.75 or more and 0.85 or less,
The intrinsic viscosity of the resin constituting the outer container is 0.65 or more and 0.75 or less.
5. A multiple container according to claim 4. The crystallinity of the inner container is lower than the crystallinity of the outer container,
A multiple container according to any one of claims 1-5. The crystallinity of the outer container is 25% or more and 40% or less,
the crystallinity of the inner container is at least 5% lower than the crystallinity of the outer container;
7. Multiple container according to claim 6. Further comprising an outside air introduction hole capable of introducing outside air between the outer container and the inner container,
A multiple container according to any one of claims 1-7 . The length of the axially outer surface side of the preform extending portion corresponding to the inner container is 0.5 with respect to the length of the axially inner surface side of the preform extending portion corresponding to the outer container. is ~0.8 times as long,
A multiple container according to any one of claims 1-8 .

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