JP7069697B2 - Manufacturing method of double-structured 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 including an inner bag container and an outer cylinder has been put into practical use as an airless bottle, for example, as 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, in the double structure as described above, when the contents of the inner bag container are discharged, a very loud noise is generated when the body of the bottle (outer container) is squeezed, especially when the container is made of polyester. There was a problem of doing. Such a sound is at a level that is perceived as noise, for example, 70 dB or more, and in some cases, it may exceed 80 dB, and improvement thereof is desired. However, most studies have been made to avoid such noise. The reality is that it has not.

For example, in Patent Document 1, a small-diameter preform for molding an inner bag container and a large-diameter preform for molding an outer container are used, and the small-diameter preform is blow-molded in a state of being inserted into the large-diameter preform. When manufacturing a double-structured container, it has been proposed to provide a chemical such as an oxygen absorber or a deodorant between the outer surface of the small-diameter preform and the inner surface of the large-diameter preform.
Further, in Patent Document 2, a mold release agent layer containing liquid paraffin is provided between the outer surface of the small-diameter preform and the inner surface of the large-diameter preform when the double-structured container is manufactured in the same manner as in Patent Document 1. It is proposed to provide.

Patent Document 1 and Patent Document 2 provide functionality by allowing various materials to exist between the inner bag container and the outer container, and for example, generate an offensive odor or permeate oxygen into the inner bag. Deterioration of the contents due to the above is suppressed, and further, the inner bag container (bag) can be quickly separated from the inner surface of the outer container to form an air layer between the two, and the inner bag can be squeezed from the outer container. The advantage of being able to quickly discharge the contents inside the container is achieved, but as far as the present inventors have confirmed through experiments, the problem of sound generation when squeezing the outer container is solved. It has not been.

Japanese Unexamined Patent Publication No. 5-228988 Japanese Unexamined Patent Publication No. 2017-186059

Therefore, an object of the present invention is to make a sound when squeezing the outer container and discharging the contents in a double-structured container consisting of an outer container and an inner bag container inserted and held in the outer container. It is an object of the present invention to provide a method for producing a double-structured container whose outbreak is effectively suppressed.

The double-structured container manufactured by the present invention comprises an outer container and an inner bag container inserted and held in the outer container, and the inner bag is formed by squeezing the outer surface of the body of the outer container. The contents contained in the container are discharged ,
A coating layer of an anti-pronunciation agent is provided between the outer surface of the inner bag container and the inner surface of the outer container, and the sound generated when the outer container is squeezed is set to 60 dB or less .
In the present invention, for the volume level emitted when the outer container is squeezed, a sound level meter is used as a measuring instrument, the distance between the outer surface of the body of the double-structured container and the measuring instrument is set to 30 cm, and the squeeze is performed. This is the maximum volume when repeated for 1 minute.

In the double-structured container of the present invention,
(1) The coating layer of the anti-pronunciation agent is formed on the outer surface of the inner bag container or the inner surface of the outer container.
(2) The pronunciation inhibitor is an oil-based solid material having a melting point of 30 to 100 ° C.
(3) The anti-pronunciation agent is wax.
(4) Both the inner bag container and the outer container are made of polyester.
Is preferable.

According to the present invention, a first preform having a test tube shape for forming an outer container and a second preform having a test tube shape for forming an inner bag container are prepared.
A coating layer of the anti-pronunciation agent is formed on the inner surface of the first preform or the outer surface of the second preform.
With the coating layer of the anti-pronunciation agent formed, the second preform forms a stack preform contained in the first preform.
Blow molding is performed by supplying a blow fluid into the second preform in the stack preform, and the blow molding is performed .
As the sound-preventing agent, a solid material having a melting point of 30 to 100 ° C. is used, and the coating layer of the sound-preventing agent is applied to the outer surface bottom portion of the second preform and its vicinity, or the inner surface bottom portion of the first preform. Provided is a method for manufacturing a double-structured container, which is formed in a portion in the vicinity thereof, and the stack preform is held in an inverted state to perform the blow molding .

The double-structured container of the present invention has an important feature in that the anti-pronunciation agent is distributed on the outer surface of the inner bag container or the inner surface of the outer container, whereby when the outer container is squeezed. The pronunciation of is effectively suppressed. For example, in a double-structured container in which a pronunciation inhibitor is not present, a sound of 70 dB or more is emitted, but in the present invention, this sound is suppressed to 60 dB or less as shown in Examples described later. .. Generally, 70 dB is a level at which a person is talking in a loud voice and feels noisy, while 60 dB is a volume at a level where he / she does not feel noisy because he / she is talking in a normal voice.

In the present invention, the material that functions as a pronunciation inhibitor can be confirmed by experiments, but basically, at least an oily solid that is in a solid state in a usage environment where a squeeze operation is performed functions as a pronunciation inhibitor. In particular, from the viewpoint of coating property, those having a melting point in the range of 30 to 100 ° C. are preferably used.

The sound generated by squeezing the body of the outer container is mainly generated when the body wall recessed by squeeze returns to its original shape, but with this alone, a very loud sound is not generated. .. For example, in a normal single-layer polyester bottle that does not have an inner bag container, such a loud noise does not occur. However, in the double-structured container, the body wall of the outer container dented by squeeze is quickly restored to its original shape, air is quickly introduced between the outer container and the inner bag container, and the next content discharge operation ( Squeeze) is designed to be done. That is, since the body wall of the outer container is designed to be relatively hard, a louder noise is generated when the outer container is restored to its original shape. Moreover, in the double-structured container, an inner bag container filled with the contents is inserted inside the outer container. For this reason, when the body wall of the recessed outer container returns to its original shape, a frictional noise due to friction with the inner bag container filled with the contents is also added, and as a result, a very loud noise, for example, 70 dB or more, is added. The present inventors are considered to generate sound.
In the present invention, by distributing a pronunciation inhibitor, for example, an oil-based solid material between the inner surface of the outer container and the inner bag container, the above-mentioned frictional noise is effectively reduced, and the volume level generated during squeeze play is 60 dB. It is possible to suppress the following.

Schematic side sectional view immediately after molding of the double structure container of this invention. FIG. 2 is a schematic side sectional view showing a first preform (preform for molding an outer container) and a second preform (preform for molding an inner bag container) used for manufacturing the double-structured container of FIG. Schematic side sectional view showing a stack preform in which a second preform is housed and held in a first preform. Schematic side sectional view showing a suitable form of a stack preform at the time of blow stretching in the manufacture of a double-structured container of the present invention.

With reference to the schematic view of FIG. 1, the double-structured container of the present invention is shown by 10 as a whole, and is composed of an outer container 1 and an inner bag container 3 housed inside the outer container 1. The pronunciation inhibitor 5 is distributed between the inner surface of the outer container 1 and the outer surface of the inner bag container 3.

In FIG. 1, the outer container 1 is formed of a neck portion 1a, a body portion 1b connected to the neck portion 1a, and a bottom portion 1c closing the lower end of the body portion 1b, and the body portion 1b and the bottom portion 1c are blow-stretched. The neck portion 1a is a portion, which is a fixed portion that is not blow-stretched, and is not thinned by blow-stretching.
An air introduction port 7 for introducing air between the inner surface of the outer container 1 and the outer surface of the inner bag container 3 is provided in the lower portion of the neck portion 1a by post-processing such as laser processing. Further, the central portion of the body portion 1b of the outer container 1 usually has a concave shape so that the squeeze operation can be easily performed.

Further, in the example of FIG. 1, the support ring 1d is formed on the outer surface of the neck portion 1a of the outer container 1.

On the other hand, the inner bag container 3 has a neck portion 3a which is a non-stretched portion and a bag portion 3b which is blow-stretched to have a thin bag shape (usually, the thickness thereof is 200 μm or less). Immediately after molding, the outer surface of the bag portion 3b is in close contact with the inner surfaces of the body portion 1b and the bottom portion 1c of the outer container 1.
In such an inner bag container 3, the neck portion 3a is fitted into the neck portion 1a of the outer container 1, and in the example of FIG. 1, the upper portion of the neck portion 3a protrudes from the neck portion 1a of the outer container 1. A screw 3c for fixing the cap with a screw is formed in this protruding portion, and further, a stopper is provided in the lower portion of the screw 3c so that the inner bag container 3 does not penetrate deeply into the outer container 1. The protrusion 3d is formed.
Of course, the form of the double-structured container 10 of the present invention is not limited to the form shown in FIG. 1, and for example, only a protrusion 3d serving as a stopper is provided at the upper end of the neck portion 3a of the inner bag container 3. A screw for attaching a cap may be provided on the outer surface of the neck portion 1a of the outer container 1 (the upper portion of the support ring 1d).

In the present invention, the above-mentioned outer container 1 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 10 has a structure in which air flows between the outer container 1 and the inner bag container 3, the outer container 1 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 1. 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, the thermoplastic resin preferably used in the present invention has a strength that allows it to quickly return to its original shape when the recessed portion of the body portion 1b of the outer container 1 is squeezed and further recessed. It is a polyester resin, especially PET, in that it can be secured.

Further, the inner bag container 3 is formed of a blow-moldable thermoplastic resin like the outer container 1.
In the double-structured container 10, since it is necessary to form an air layer between the bag portion 3b of the inner bag container 3 and the body portion 1b of the outer container 1 when discharging the contents, the inner bag container is usually used. As the thermoplastic resin for forming 3, a resin that can be quickly peeled off from the outer container 1 is preferably used, but in the present invention, between the outer container 1 and the inner bag container 3. Since the sound-preventing agent 5 is present in the container, it does not matter if the thermoplastic resin forming the inner bag container 3 is of the same type as the thermoplastic resin forming the outer container 1, and in particular, the sound-preventing agent. Since it is easy to set the blow stretching conditions for the presence of 5, it is preferable that the thermoplastic resin for forming the inner bag container 3 and the thermoplastic resin forming the outer container 1 are of the same type.
Therefore, although it has been described above that the outer container 1 is preferably made of polyester resin, it is preferable that the inner bag container 3 is also made of polyester resin.

In the double-structured container 10 of the present invention, as shown in FIG. 1, the pronunciation inhibitor 5 is present between the inner surface of the outer container 1 and the outer surface of the inner bag container 3.
As shown in Examples described later, the pronunciation inhibitor 5 emits a volume of 60 dB or less when the body portion 1b (particularly a recessed portion) of the outer container 1 of the double-structured container 10 is squeezed. Strictly speaking, it is necessary to actually carry out a laboratory test to confirm what kind of material functions as the anti-pronunciation agent 5, which is an agent that can be suppressed.
The oily material used as the anti-pronunciation agent is preferably solid at room temperature from the viewpoint of anti-pronunciation effect and handling. Generally, when blow molding from a preform to a bottle, the surface area of the container is significantly increased. Especially in the case of an airless bottle, the draw ratio is designed to be large in order to make the inner layer container thin and easy to crush. Therefore, since the anti-pronunciation layer held in the stack preform is stretched thinly, it is necessary to thicken the anti-pronunciation layer in order to provide a sufficient anti-pronunciation function. For example, when a material such as liquid paraffin that is liquid at room temperature is used, there is a concern that it may flow due to its own weight and leak from the air introduction hole 7 provided in the preform for forming the outer container.
However, when the oily material known as a lubricant or the like is in a solid state under the usage environment of the double-structured container 10, for example, by spraying with an appropriate solvent or dipping in a melted state, etc. A sufficient amount can be present on the inner surface of the body portion 1b of the outer container 1 or the outer surface of the bag portion 3b of the inner bag container 3 of the squeezed portion. Further, since these are held in a portion that is stably squeezed without falling in a solid state under the usage environment even after bottle molding, between the inner surface of the outer container 1 and the outer surface of the inner bag container 3 during squeeze. Friction is effectively reduced, and as a result, the volume of the sound generated during squeeze can be set to 60 dB or less.

In the present invention, the solid material exhibiting slipperiness as described above is a material having a melting point that exists in a solid state under the usage environment of the double-structured container 10 and melts and flows during blow molding, specifically. Various waxes having a melting point of 30 ° C. to 100 ° C. (particularly 35 to 70 ° C.), for example, rice wax, carnauba wax, paraffin wax, microcrystalline wax, polyethylene wax, candelilla wax, rice wax, wood wax, beeswax and the like are suitable. Is. Further, oils and fats such as palm oil, coconut oil and cacao butter having a melting point within the above range can be preferably used, and further, higher aliphatic amides and the like can also be used.

In the present invention, the pronunciation inhibitor 5 as described above is at least in the squeeze region (squeeze region) of the body portion 1b of the outer container 1 between the inner surface thereof and the outer surface of the bag portion 3b of the inner bag container 3. It may be present, but the amount of the anti-pronunciation agent present in such a region is preferably 100 mg / m ² or more, more preferably 400 mg / m ² or more. That is, if this amount is small, the effect of suppressing the sound generated during squeeze play is not sufficiently exhibited.
By the way, as a means for allowing the pronunciation inhibitor 5 to exist in the squeeze region, the pronunciation inhibitor is blended in the thermoplastic resin forming the inner surface of the outer container 3 or the thermoplastic resin forming the inner bag container 3. It should be noted that an internal addition method in which the anti-pronunciation agent is bleeding in the squeeze region can be considered, but it is difficult to have a sufficient amount of the anti-pronunciation agent as described above by such a method. Therefore, in the present invention, a method is preferably adopted in which a layer of the anti-pronunciation agent is provided on the inner surface of the body portion 1b of the outer container 1 or the outer surface of the bag portion 3b of the inner bag container 3 by coating.

In that the layer of the sound inhibitor 5 is formed by the coating as described above, the double-structured container of the present invention is a first preform (outer) obtained by injection molding using a resin for an outer container. A second preform (preform for inner bag container molding) obtained by injection molding using a resin for inner bag container and a preform for inner bag molding is used, and the second preform is used as the first preform. It is manufactured by a method (stack method) in which a stack preform having a multi-layer structure is formed by inserting it into the preform of the above, and biaxial stretch blow molding is performed on this stack preform.
That is, according to the stacking method, the layer of the pronunciation inhibitor 5 described above can be easily formed by coating on a predetermined portion of the first preform or the second preform.

In FIGS. 2 and 3 for explaining the above stacking method, the stack preform for forming a double-structured container of FIG. 1 is shown at 20 as a whole in FIG. 3 and is shown in FIG. As described above, it is formed from the first preform 11 (see FIG. 2A) and the second preform 13 (see FIG. 2B), both of which have a test tube shape.
That is, the first preform 11 is a preform for molding the outer container, the second preform 13 is the preform for molding the inner bag container, and the second preform 13 is inserted into the first preform. By fitting and holding the stack preform 20 to be subjected to the blow stretching step, the stack preform 20 is assembled.

As can be understood from FIG. 2, both the first preform 11 and the second preform 13 have a portion corresponding to the neck portion 1a of the outer container 1 and the neck portion 3a of the inner bag container 3. That is, none of these portions are stretch-molded portions, and the first preform 11 has a support ring 1d and an air introduction port 7 formed by post-processing after injection molding, and has a fine 2 Preform 13 has a screw 3c and a protrusion 3d.
Further, the tubular portion 11b in which the lower end of the lower portion of the neck portion 1a of the first preform 11 is closed is stretch-molded, and the outer container 1 is formed into the body portion 1b and the bottom portion 1c by blow stretching. It is shaped.
Further, the tubular portion 13b in which the lower end of the lower portion of the neck portion 3a of the second preform 13 is closed is stretch-molded, and is shaped into the form of the bag portion 3b of the inner bag container 3 by blow stretching. Will be done.

By inserting the second preform 13 into such a first preform 11, the stack preform 20 having the form shown in FIG. 3 is assembled, placed in a blow mold, and the neck portion is used with a predetermined jig. The portion containing 1a and 3a is fixed (the region indicated by X in FIG. 3), and the stack preform 20 is stretch-moldable by high-frequency heating or the like (glass transition of the resin forming the preforms 11 and 13). Heat to a point temperature or higher and lower than the melting point), insert a stretch rod (not shown) into the stack preform 20 (second preform 13), stretch it in the uniaxial direction, and blow air or the like. By supplying the fluid and expanding it in the circumferential direction, the double-structured container 10 having the form shown in FIG. 1 is obtained. That is, in FIG. 3, the region indicated by Y of the stack preform 20 is a portion to be stretch-molded.

In the present invention, by molding the double-structured container 10 by the stacking method as described above, the coating layer of the sound-preventing agent 5 can be easily formed between the outer container 1 and the inner bag container 3. can.
For example, for a double-structured container by co-injection molding in which the resin for the outer container 1 and the resin for the inner bag 3 are selected so as to have no affinity with each other and show non-adhesiveness. In the means of molding a preform and supplying it by stretch blow molding, in order to distribute the sound-preventing agent 5 between the outer container 1 and the inner bag container 3, the sound-preventing agent 5 is inevitably dispersed in the resin. There is no choice but to adopt the internal addition method of forming the molding and distributing it by bleeding of the sound-preventing agent 5. As already mentioned, in such an internal addition method, it is impossible to distribute an anti-pronunciation agent in an amount effective for preventing pronunciation.
However, when the above-mentioned stacking method is adopted, for example, the preform for the outer container 1 (first preform 11) and the preform for the inner bag container 3 (second preform 13) are separate. By easily forming a coating layer of the pronunciation inhibitor 5 on the predetermined portions of the preforms 11 and 13, the pronunciation inhibitor 5 is placed between the outer container 1 and the inner bag container 3. Can be distributed.

For the coating of the anti-pronunciation agent 5, for example, a coating liquid of the anti-pronunciation agent 5 is prepared using an appropriate volatile solvent, and the coating liquid is stretch-molded by spraying or dipping the first preform 11. It can be applied to the outer surface of the portion (cylindrical portion 11b) or the outer surface of the stretch-molded portion (cylindrical portion 13b) of the second preform, and then dried.
In this way, the stack preform 20 of FIG. 3 is formed by using the first preform 11 or the second preform 13 in which the coating layer of the sound inhibitor 5 is formed on the outer surface or the inner surface, and the blow described above is performed. By performing stretch molding, as shown in FIG. 1, the pronunciation inhibitor 5 can be distributed between the outer container 1 and the inner bag container 3.
In the blow stretching molding, since the sounding inhibitor 5 is melted and is in a fluid state, it is stretched together with the first preform 11 and the second preform 13 without causing film breakage or the like. The pronunciation inhibitor 5 can be distributed in a predetermined squeeze area.

However, in the present invention, in particular, a solid material having a melting point of 30 to 100 ° C. can be selected as the pronunciation inhibitor 5, so that, for example, the pronunciation inhibitor 5 is heated and melted, and a second solvent is added to this melt. By dipping the reform 13, the coating layer of the pronunciation inhibitor 5 can be easily formed without using a solvent. When forming the coating layer of the sound inhibitor 5 in this way, for example, it is not necessary to coat the entire outer surface of the stretch-molded portion (cylindrical portion 13b) of the second preform 13, and the sound inhibitor 5 is not necessary. Only the bottom of the shaped portion 13b and its vicinity may be immersed in the melt of the sound-preventing agent 5 to form a coating layer.

That is, the stack preform 20 assembled using the second preform 13 in which the coating layer of the sound inhibitor 5 is formed only on the bottom of the tubular portion 13b and its vicinity thereof is shown in FIG. As shown above, it is held in an inverted state, and blow stretching molding is performed in this state. In FIG. 4, the coating layer of the anti-pronunciation agent 5 is indicated by 30.

By performing blow stretching molding in such an inverted state, the coating layer 30 of the sounding inhibitor 5 melts and flows together with blow stretching and diffuses downward, and as a result, the inner bag container 3 includes a squeeze region. As shown in FIG. 1, it is possible to obtain a double-structured container 10 in which the sound-preventing agent 5 is distributed between the outer container 1 and the inner bag container 3 so as to spread over the entire outer surface of the bag portion 3b.
In this case, the coating amount of the pronunciation inhibitor 5 should be set so that a predetermined amount of the pronunciation inhibitor 5 is distributed at least in the squeeze region in consideration of the fact that the coating layer 30 spreads over the entire bag portion 3b. good.

The double-structured container 10 of the present invention manufactured as described above has a check valve known per se on the neck portion 1a of the outer container 1 after the contents are housed in the bag portion 3b of the inner bag container 3. It is used with a cap attached.

In such a double-structured container 10 of the present invention, the contents filled in the inner bag 3 are squeezed (pressed), for example, by squeezing (pressing) the recessed portion (squeeze region) of the body portion 1b of the outer container 1. , The contents are discharged one by one by being pressed and dented, and the volume of the bag portion 3b of the inner bag container 3 is reduced. Since air is introduced between the inner surface of 1b and an air layer is formed, the subsequent contents can be effectively discharged.
When the contents are discharged by such a squeeze play, in the present invention, the pronunciation associated with the squeeze play is suppressed to 60 dB or less, and an effect not found in the conventionally known double-structured container can be obtained.

The excellent effect of the present invention will be described with reference to the following experimental examples.

A sound level meter (manufactured by B & K Precision) is used to measure the pronunciation that accompanies the squeeze of the container. Evaluated at the maximum volume of.

A commercially available PET resin for bottles (intrinsic viscosity: 0.84 dl / g) sufficiently dried by a dehumidifying dryer was supplied to the hopper of the injection molding machine, and the first preform in the shape of a test tube for molding an outer container was used. A second preform in the shape of a test tube for molding the inner bag container was obtained.

(Comparative Example 1)
A second preform was inserted into the first preform described above to obtain a stack preform. Further, the stack preform was heated by a quartz heater and an iron core for heating and blow-molded to obtain a cylindrical bottle having an internal volume of about 400 ml. The draw ratio was 2.5 times in the vertical direction and 2.5 times in the circumferential direction with respect to the preform for the outer layer, 2.7 times in the vertical direction and 4.2 times in the circumferential direction with respect to the preform for the inner layer. rice field.
When the obtained double-structured container was squeeze and the pronunciation was measured, the maximum volume was 83 dB, which was an unpleasant level.

(Example 1)
The second preform of Comparative Example 1 was dipped with a molten paraffin wax (manufactured by Wako Pure Chemical Industries, Ltd., melting point 44 to 46 ° C.), and the paraffin wax was adhered to the outer surface of the second preform. This inner layer preform was inserted into the outer layer preform to form a double-structured preform, which was blow-molded into a bottle shape by the same method as in Comparative Example 1.
The amount of paraffin wax applied, which was calculated from the amount of paraffin wax attached and the surface area of the bottle, was 1100 mg / m ² . When the obtained double-structured container was squeeze and the pronunciation was measured, the maximum volume was 51 dB, and it was confirmed that the pronunciation by the squeeze was effectively suppressed.

(Example 2)
The method of applying paraffin wax to the inner layer preform was changed to a spray coat, and bottle molding was carried out in the same manner as in Example 1 except that the mouth and bottom of the preform were masked and the paraffin wax was attached only to the body. .. The amount of paraffin wax applied was 550 mg / m ² .
When the obtained double-structured container was squeeze and the pronunciation was measured, the maximum volume was 53 dB, and the pronunciation by the squeeze was effectively suppressed.

(Example 3)
The wax to be adhered was bottle-molded in the same manner as in Example 2 except that the wax to be attached was changed to paraffin wax (manufactured by Wako Pure Chemical Industries, Ltd., melting point 68 to 70 ° C.). The amount of paraffin wax applied was 510 mg / m ² .
When the obtained double-structured container was squeeze and the pronunciation was measured, the maximum volume was 58 dB, and the pronunciation by the squeeze was effectively suppressed.

(Comparative Example 2)
Bottle molding was carried out in the same manner as in Example 2 except that the coating amount of paraffin wax was adjusted to 80 mg / m ² .
When the obtained double-structured container was squeeze and the pronunciation was measured, the maximum volume was 67 dB, and a sufficient pronunciation suppressing effect could not be obtained.

1: Outer container 3: Inner bag container 5: Anti-pronunciation agent 7: Air inlet 10: Double-structured container 11: First preform 13: Second preform 30: Anti-pronunciation agent coating layer

Claims (1)

Prepare a first preform in the shape of a test tube for molding the outer container and a second preform in the shape of a test tube for molding the inner bag.
A coating layer of the anti-pronunciation agent is formed on the inner surface of the first preform or the outer surface of the second preform.
With the coating layer of the anti-pronunciation agent formed, the second preform forms a stack preform contained in the first preform.
Blow molding is performed by supplying a blow fluid into the second preform in the stack preform, and the blow molding is performed .
As the sound-preventing agent, a solid material having a melting point of 30 to 100 ° C. is used, and the coating layer of the sound-preventing agent is applied to the outer surface bottom portion of the second preform and its vicinity, or the inner surface bottom portion of the first preform. A method for manufacturing a double-structured container, which is formed in a portion in the vicinity thereof, and the stack preform is held in an inverted state to perform blow molding .

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