JPH11245941A - Laminated prefoam, and its forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forming method of a laminated prefoam to manufacture a laminated container in which only an inner layer is shinkingly deformed and the shape of its outer layer is not deformed when the inside of the laminated container of the double-layered structure formed of at least the inner layer and the outer layer is in a vacuum condition. SOLUTION: A thermoplastic synthetic resin having the property to meet the application purpose of a laminated container is selected, a prefoam piece 2a to constitute an outer layer of the container and a prefoam piece 3a to constitute an inner layer are separately formed in the shape capable of being overlapped with each other to integrate them, and a laminated prefoam body 1A in which a small hole 2b for introducing the atmosphere is formed in the prefoam piece 2a forming the outer layer and the biaxial stretching blow molding can be achieved, is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preform suitable for manufacturing a laminated container having at least a two-layer structure of an inner layer and an outer layer. A laminated preform for manufacturing a laminated container in which, when the inside of the container is in a reduced pressure state, only the inner layer is contracted and deformed, and the external shape of the container is not deformed. And its manufacturing method.

[0002]

2. Description of the Related Art Conventionally used synthetic resin containers are made of a resin layer containing no additives such as a plasticizer, or a resin layer excellent in gas shielding properties for preventing evaporation and oxidation of contents. There is known a laminated container having a structure in which an outer layer made of a resin having excellent mechanical or physical strength is laminated on an inner layer made of the resin. Then, in order to mold such a laminated container, a resin having mutual melting property or adhesiveness is selected from resins having excellent properties as described above constituting the inner and outer layers, and simultaneously extruded. Or
Laminated parison molded by coaxial extrusion molding through an adhesive layer or by tightly bonding the outer layer to the inner layer,
A method of molding into a hollow container by blow molding or the like is generally adopted.

[0003] However, in a sealed laminated container in which a hollow container is formed by using the laminated parison formed by the coextrusion molding method as described above to prevent outside air from entering the container, the container is filled with When the contents of the container are reduced due to evaporation or use and the inside of the container is reduced in pressure, the body of the container is compressed by the atmospheric pressure and the outer shape of the container is deformed. There are drawbacks such as the appearance being impaired and the difficulty in pouring out the contents to the end.

[0004] In order to solve the above-mentioned drawback, a laminated hollow container is formed by blow-molding a laminated parison having an inner layer and an outer layer formed of a releasable resin. The applicant has already proposed a container in which when the pressure is reduced, the inner layer is peeled off from the outer layer and only the inner layer is contracted and deformed, so that the outer shape of the container is not deformed (Japanese Patent Application Laid-open No. 4-339759). However, in such a container, a portion where the inner layer and the outer layer are in contact with each other is adhered at the mouth and neck or the trunk of the container. However, since the outer layer may be partially deformed by being pulled, the outer layer must have a structure that can withstand the deformation.

Further, instead of providing the adhesive layer and laminating the inner and outer layers as described above, the inner layer is formed by using a synthetic resin material having a high flexural modulus, and a flange-like engagement is formed at the mouth and neck end of the container. In some cases, a joining portion is formed, and the inner and outer layers are engaged and welded at the flange portion to form a laminated container, so that the inner layer can be peeled off. (See Japanese Patent Application Laid-Open No. 6-345069) However, in order to mold such a container, a special structure is employed in which the shape of the mold for blow molding and the shape of the mandrel portion of the blow device match the shape of the mouth and neck. Must be prepared, so that a mandrel or the like that matches the shape of the engaging portion must be prepared for each type and size of container, and the molding cost is high because it cannot be made with a normal extrusion blow molding machine. That is inevitable.

Further, any of the above laminated hollow containers is
A hollow container is blow-molded by using a parison molded by a co-extrusion molding method in which an inner layer and an outer layer are simultaneously extruded and integrally molded (so-called direct blow method). Since the mouth of the container is to be finished, to form a laminate comprising a combination of the material constituting the inner layer and the material constituting the outer layer of the container, various conditions are required depending on conditions for co-extrusion. Because of the restrictions, the degree of freedom in selecting the material is narrow. Further, in forming a hollow container by the direct blow method using such a laminated preform, the circumferential stretching of the container can be easily performed,
Axial stretching was very difficult, and the effect as expected was not obtained. Especially,
Since the direct blow method is a parison method, it is very difficult to stretch and orient to improve physical properties.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method for forming a preform for manufacturing a laminated container having a structure in which the inner layer can be easily separated from the outer layer. And when selecting the material of the synthetic resin to be the inner layer, in order to increase the degree of freedom to combine the material of the inner and outer layers, with a wider selectivity than the conventional case of forming a parison by co-extrusion molding It is an object of the present invention to provide a laminated preform having a structure capable of forming a laminated preform by a molding method and forming various kinds of laminated hollow containers by biaxial stretch blow molding.

[0008]

SUMMARY OF THE INVENTION In a laminated container to be molded, a preform piece serving as an outer layer and a preform piece serving as an inner layer are made of a thermoplastic resin having properties suitable for each purpose. After selecting the resin and molding the resin separately by injection molding, both preform pieces are molded into a shape that can be overlapped, or both preform pieces are overlapped and fitted, or Then, it is crimped or integrated to form a laminated preform that can be blow-molded. However, the preform body is heated to a temperature at which blow molding can be performed and then subjected to biaxial stretch blow molding and blow molded into a hollow container. Thus, a laminated preform suitable for biaxial stretch blow molding by a so-called cold parison method is provided. Molding.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preform piece having a predetermined shape to be an outer layer of a laminated container is molded by injection molding using a thermoplastic resin having transparency, impact resistance, and physical strength. A small hole for ventilation is formed at an appropriate position on the preform piece. On the other hand, a preform piece having a predetermined shape to be an inner layer of the laminated container is heat-bonded to the outer preform piece with low adhesive strength and releasability, and has transparency, gas barrier property, non-toxicity and the like. The outer layer preform piece is molded by injection molding using a plastic resin so as to overlap with the outer layer preform piece.

Subsequently, after fixing the outer layer preform piece to a mold of a preform molding apparatus, the inner layer preform piece is overlapped with and fitted to the outer layer preform piece. To form a laminated preform that can be biaxially stretch blow-molded.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention of the present application will be described below with reference to the drawings based on an optimum embodiment. FIG. 1 shows a cylindrical laminated preform according to a first embodiment of the present invention and a molding process thereof, and FIG. 2 shows a blow molded product using this laminated preform. 1 illustrates a bottle-shaped laminated hollow container 1. The body wall of the hollow container 1 is composed of an outer layer 2 that retains the outer shape and an inner layer 3 that can be peeled off. The outer layer 2 at the bottom of the container is provided with an air introduction hole 4. When the content contained in the hollow container evaporates or is reduced due to being used and the inside of the container is reduced in pressure, the inner layer 3 is changed from the outer layer 2 to the inner layer 3. It is formed in a layer configuration that allows easy peeling.

The laminated preform 1 of the present invention described above.
In order to mold A, as shown in FIG. 1 (a), a preform piece 3a serving as an inner layer having a predetermined shape according to the final product is injection-molded with polyethylene terephthalate resin (PET) to form a test tube. The preform piece 2a to be an outer layer is formed into a shape that can be fitted so as to wrap the inner layer preform piece 3a by injection molding a polyacrylate resin (U polymer). Simultaneously with molding, small holes 2a for forming the air introduction holes 4 when the laminated hollow container 1 is molded are formed in the bottom of the outer layer preform piece 2a and other appropriate portions.

Next, after fixing the outer layer preform piece 2a to a preform molding device or other mold so as to be fittable, the inner layer preform piece 3a is overlapped on the outer layer preform piece 2a. Supply and press the inner layer preform piece 3 as indicated by the arrow with a mold or other pressing tool.
a is pressed against the outer layer preform piece 2a, and FIG.
As shown in (b), a cylindrical laminated preform 1A in which both preform pieces are integrally laminated is formed.

The laminated hollow container 1 shown in FIG. 2 has a screw thread 5 for screwing a screw cap onto the mouth and neck of the container to seal the container.
However, in order to form the threaded portion on the mouth and neck of the hollow container, as shown in FIGS. 1A and 1B, the mouth and neck of the inner layer 3a of the laminated preform 1A are formed. It is necessary to form the threaded portion 3b in the portion. For this purpose, in the process of molding the laminated preform 1A, the screw portion 3b and the neck ring portion 3c are simultaneously formed in the portion to be the mouth and neck when the preform piece 3a to be the inner layer is injection-molded. When the preform piece 2a to be the outer layer is formed by injection molding, the end portion thereof has the neck ring portion 3c.
It is preferable that an undercut portion is provided on the fitting piece 2c to be fitted with and formed, and at the same time, a small hole 2b is formed on the bottom thereof.

[0015] Without using a screw cap to seal the container,
A sealing body such as a film is closely attached to the opening end to seal tightly.
Alternatively, when forming a container of a type in which the lid is fitted to the mouth and neck and welded and sealed, as shown in FIG. 7A, an engagement step 3d is formed at the mouth and neck end. The inner layer preform piece 3a thus formed and the outer layer preform piece 2a molded into a shape similar to the inner layer preform piece 3a are fitted to each other to engage the engaging step 2 at the mouth and neck end.
7d, the inner layer preform piece 3a is fitted to the outer layer preform piece 2a, and as shown in FIG. Of the outer layer preform piece 2a on the engaging projection 3e.
e is engaged and the laminated preform 1A laminated is biaxially stretch blow-molded to form a hollow container.

FIG. 3 shows a laminated preform according to a second embodiment of the present invention. Such a bowl-shaped laminated preform 21A is a wide-bottle bottle as shown in FIG. This is suitable for blow molding the laminated hollow container 21 having a shape. To form such a laminated preform 21A, a preform piece 23a serving as an inner layer having a predetermined size and thickness according to the shape of the final product is formed.
Is formed into a bowl shape by injection molding, and a flat flange portion 23b is formed at the edge thereof. The preform piece 22a to be the outer layer is replaced with the inner layer preform piece 23a.
And separately formed by injection molding into a shape that can be fitted to the outer surface of the inner layer preform piece 23a so that the end of the flange portion 22c formed on the edge is flush with the plane of the flange portion of the inner layer preform piece 23a. At the same time, at the bottom of the outer layer preform piece 22a or an appropriate portion, the air introduction hole 24 is provided.
Is formed.

The outer layer preform piece 22a
Is set in a preform molding apparatus or other molding die, and then the inner layer preform piece 23a is supplied so as to overlap the outer layer preform piece 22a. To form a bowl-shaped laminated preform 21A.

The laminated preform 21A shown in FIG.
Has an intermediate layer 25a between the outer layer preform piece 22a and the inner layer preform piece 23a,
When the intermediate layer is provided in this manner, it is common to form the intermediate layer using a thermoplastic resin having good adhesiveness with the outer layer and good releasability with the inner layer. Alternatively, the intermediate layer may be formed using a thermoplastic resin having good adhesion to the inner layer and good releasability from the outer layer.

The preform shown in FIG. 5 is a laminated preform showing a third embodiment of the present invention, and the laminated preform 31A having a dish shape as described above is a cup shown in FIG. It is suitable for blow molding the laminated hollow container 31 having a shape.

To form such a laminated preform 31A, a preform piece 33a serving as an inner layer having a predetermined shape according to the shape of the final product is formed into a dish shape by injection molding, and a flat edge is formed. The preform piece 32a to be the outer layer is formed into a shape that can be fitted to the outer surface of the inner layer preform piece 33a by injection molding separately, and the flange at the edge is formed. The portion 32c is formed so that the end is raised so as to surround the flange portion 33c of the inner layer preform piece 33a and is flush with the flange portion 33c of the inner layer. A small hole 32b serving as an air introduction hole 34 is formed in an appropriate portion.

Subsequently, the outer layer preform piece 32a formed as described above is set in a mold of a preform molding apparatus, and then the inner layer preform piece 23a is overlapped with the outer layer preform piece 32a. After supplying to
The two preform pieces are pressed by a molding die and pressed to form a laminated preform 31A.

The peelable laminated hollow container 1 formed from the laminated preform 1A of the present invention has an opening formed by setting the pouring pump 7 after filling the container with the content liquid as shown in FIG. When the product is sealed by screwing and fixing the screw lid 6 to the container, and the container is used by operating the pouring bed 7a of the pouring pump 7, the liquid content is passed through the suction pipe 7b. The inside of the container is gradually reduced and the inside of the container is decompressed. When the inner layer 3 is easily separated from the outer layer 2, air flows in from the air introduction hole 4 and the inner layer 3 contracts but the outer layer 3 contracts. 2 does not shrink, so that the outer shape of the container does not deform and does not impair the appearance.

In the above-described forming of the laminated preform, the outer layer preform piece is formed by injection molding in order to provide the laminated preform with a small hole serving as an air introduction hole when formed into a laminated container. At the same time, the method of forming a small hole in an appropriate portion of the outer layer preform piece was adopted, but without being limited to such a method, after forming the outer layer preform piece, the outer layer preform piece Small holes may be formed in appropriate portions of the pieces, or a method of forming small holes in appropriate portions of the outer layer of the preform after forming the laminated preform may be employed. Simultaneous with the molding of the preform piece can be easily and stably formed.

The bowl-shaped preform shown in FIG. 3 and the bowl-shaped preform shown in FIG.
In any case, no thread is provided on the peripheral surface of the edge, but these preforms are molded in the same manner as the preform of the first embodiment shown in FIG. As shown, it is also possible to provide the threaded portions 23b and 33b on the outer peripheral surface of the edge.

Using the preforms 21A and 31A having the screw portions formed on the outer peripheral surface of the opening end, the container blow-molded into the shape shown in FIGS. Since the lid can be screwed and sealed, it can be used as a container accompanied by heat filling and heat treatment. Further, the small holes 2b and the like serving as the air introduction holes 4 of the container do not necessarily need to be provided at the bottom of the outer layer preform, and may be provided at the side wall portion. A narrow groove may be appropriately provided on the engaging contact surface.

As described above, according to the present invention, the preform pieces forming the inner layer and the preform pieces forming the outer layer are separately injection-molded to form a laminated preform. Unlike the case of forming a laminated preform, there are no various restrictions for co-extrusion, so the selectivity of the materials constituting the inner layer and the outer layer is large, and it is composed of the same kind of synthetic resin. It is also possible to use various synthetic resins having a small molding temperature difference in combination.

[0027]

The laminated preform of the present invention is obtained by separately injection-molding a preform piece for forming the inner layer and a preform piece for forming the outer layer, and superimposing, fitting and laminating. Since it is engaged and fixed at one end of the preform, there is no need to provide an adhesive layer or co-extrusion molding, so that preform molding is easy and a synthetic resin of material can be selected. Because it is wide,
The production cost can be kept low and the productivity can be increased.

Since the laminated preform of the present invention does not require the use of an adhesive layer between the inner layer and the outer layer, when the container discarded after use is recovered and reused, the inner layer and the outer layer are not used. Can be easily separated, and resources of different materials are not mixed into the separated raw materials, so that the resources can be easily reused.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view showing a forming step of a laminated preform of the present invention, and FIG. 1B is a cross-sectional view showing a formed cylindrical laminated preform.

FIG. 2 is a sectional view of a laminated container formed from the laminated preform shown in FIG.

FIG. 3 is a cross-sectional view of a bowl-shaped laminated preform of the present invention.

4 is a sectional view of a laminated container formed from the laminated preform shown in FIG.

FIG. 5 is a sectional view of a dish-shaped laminated preform of the present invention.

6 is a sectional view of a laminated container formed from the laminated preform shown in FIG.

7A is a sectional view showing a modification of the preform shown in FIG. 1, and FIG. 7B is a sectional view showing another modification of the preform shown in FIG.

FIG. 8 is a sectional view showing another modified example of the preform shown in FIG.

FIG. 9 is a cross-sectional view showing another modification of the preform shown in FIG.

FIG. 10 is a cross-sectional view showing a usage form of the laminated container shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laminated hollow container 2 Outer layer 3 Inner layer 4 Atmosphere introduction hole 5 Thread 6 Screw cover 7 Discharge pump 1A Laminated preform 2a Outer layer preform piece 2b Small hole 2c Fitting piece 3a Inner layer preform piece 3b Screw part 3c Neck ring part 7a Head 7b Suction pipe

Claims (13)

[Claims] 1. A preform piece for forming an inner layer formed by injection molding a thermoplastic resin into a predetermined shape, and a thermoplastic resin injection molded into a shape in which the preform piece can be fitted. The preform piece forming the outer layer is overlapped, pressure-bonded and peelably integrated, and a small hole for forming an air introduction hole in the laminated hollow container is provided. Laminated preform for forming a laminated hollow container to be formed. 2. The laminated hollow container according to claim 1, wherein the preform piece forming the inner layer and the preform piece forming the outer layer are formed in a bottomed cylindrical shape. Laminated preform for molding. 3. The laminated hollow according to claim 1, wherein the preform piece forming the inner layer and the preform piece forming the outer layer are formed in a bowl shape with a bottom. A laminated preform for forming containers. 4. The laminated hollow according to claim 1, wherein the preform pieces forming the inner layer and the preform pieces forming the outer layer are formed in a dish shape with a bottom. A laminated preform for forming containers. 5. The preform piece forming the outer layer is integrally formed by engaging an engaging piece formed at an end thereof with an outer peripheral surface of an end part of the preform piece forming the inner layer. A laminated preform for molding the laminated hollow container according to any one of claims 1 to 4. 6. The preform piece forming the inner layer, wherein a screw portion for screwing a lid body is formed on an outer peripheral surface of an upper end portion of the preform piece. A laminated preform for forming the laminated hollow container described. 7. The preform piece forming the outer layer is provided with a small hole at the bottom for forming an air introduction hole in the laminated hollow container. 5. A laminated preform for forming the laminated hollow container described in any one of items 4 to 4. 8. A preform piece serving as an inner layer of a laminated preform is formed into a predetermined shape suitable for the shape of a container by injection molding of a thermoplastic synthetic resin, while a preform piece serving as the inner layer is formed. Forming a preform piece serving as an outer layer having a shape that can be fitted, fitting the outer layer preform piece to the inner layer preform piece, and then pressing to form a laminated preform, and A method for forming a laminated preform for forming a laminated hollow container, wherein a small hole for forming an air introduction hole in the laminated hollow container is formed in the preform. 9. The laminated hollow container according to claim 8, wherein the preform piece serving as the inner layer and the preform piece serving as the outer layer are formed into a bottomed cylindrical shape. A method for forming a laminated preform. 10. The laminated hollow container according to claim 8, wherein the preform piece serving as the inner layer and the preform piece serving as the outer layer are formed in a bowl shape with a bottom. For forming a laminated preform. 11. The laminated hollow container according to claim 8, wherein the preform piece serving as the inner layer and the preform piece serving as the outer layer are formed into a dish with a bottom. For forming a laminated preform. 12. A thread portion and a neck ring portion are formed in a portion to be a mouth and neck portion of the container at an upper end portion of the preform piece serving as the inner layer, and an upper end of the preform piece serving as the outer layer is provided. The lamination for forming a laminated hollow container according to claim 8, wherein an engagement piece for engaging with the neck ring portion is formed on the portion, and an undercut portion is formed on the engagement piece. Preform molding method. 13. The laminated hollow container according to claim 8, wherein a small hole for forming an air introduction hole of the container is formed in a body wall portion of the preform piece serving as the outer layer. A method for molding a laminated preform for molding.