JP2000280329A - Two-layer-structure preform for draw blowing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two-layer-structure preform free from cracking, shift and peeling in the bottom part of a two-layer plastic bottle of which the outside has barrier properties, in regard to molding of the plastic bottle having the barrier properties by draw blowing. SOLUTION: This two-layer-constituted preform is composed of an outer preform 10 so molded as to have a flange part 16, a cylindrical body part 12 and a bottom part 14 and to be provided with a hole part 18 in the bottom part 14 and of an inner preform 20 so molded as to have a mouth and neck part 26 and also a cylindrical body part 22 and a bottom part 24 being in close contact with the inner surface of the outer preform 10. In this case, a practically circular groove or the like is provided in one side of the bottom part of the outer preform 10 at least, in the vicinity of the peripheral edge of the hole part 18 thereof, and the resin of the inner preform 20 opposite to the hole part 18 of the outer preform 10 is filled and formed in the hole part so that it covers further the outer surface of the bottom part of the outer preform.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-layer preform for stretch blow molding used for molding a plastic bottle or the like by a stretch blow molding method. The present invention relates to a two-layer preform for stretch blow molding for a barrier plastic bottle.

[0002]

2. Description of the Related Art Conventionally, so-called PET bottles using polyethylene terephthalate have been widely used as stretch blow-molded containers for beverages and the like, but the applications have been further expanded to protect the contents from ultraviolet rays, oxygen and water vapor. Barrier PET bottles have become required.

[0003] In the production of this barrier PET bottle, two-layer molding in which a layer made of a barrier resin is applied to the outer layer of a conventional PET bottle has been attempted.

[0004] As the two-layer molding method, there is a method of stretch blow molding using a two-layer preform. A two-layer preform for this stretch blow molding is, for example, as shown in FIG. A cylindrical body (12) having a flange (16) at the upper end and a bottom (14) at the lower end;
And an outer preform (10) made of a barrier resin formed by providing a hole (18) in the bottom (14); and an outer preform (10) having a mouth and neck portion (26) at the top.
A cylindrical body (22) closely attached to the inner surface and a bottom (2
4) and an inner preform (20) made of PET and molded.

[0005]

However, when the above-described two-layered preform is formed by stretch blow, as shown in FIG. 7, for example, a stretch rod (70) inserted into the preform is used. Cracks occur in the stretched bottom (14) of the outer preform (10), or the stretched bottom (14) is
There is a problem that the desired barrier property cannot be obtained or the drop strength is impaired due to displacement or separation from the bottom portion (24) of (0).

Another problem is that the flange portion of the outer preform shifts or peels off from the mouth and neck of the inner preform.

The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to provide a barrier plastic bottle which blocks oxygen, water vapor, ultraviolet rays, etc., in a stretch blow molding process. A two-layer preform that does not have cracks, misalignments, or peeling is provided on the bottom barrier layer of a two-layer plastic bottle having an outer side as a barrier layer, thereby providing a barrier property that is excellent in barrier properties and resistant to falling. The object is to provide a layered plastic bottle.

[0008]

Means for Solving the Problems In order to achieve the above object, the present invention firstly provides a cylindrical body having a flange at the upper end and a bottom at the lower end. An outer preform made of a barrier resin formed by forming a hole at the bottom, a mouth and neck at the upper end, a cylindrical body closely adhered to the inner surface of the outer preform, and a bottom at the lower end. A stretch blow-molded two-layered preform comprising a molded inner preform made of a resin for a container body, wherein at least one surface of a bottom portion near a periphery of a hole of the outer preform has a substantially circular shape. Are formed so that the resin of the inner preform facing the hole portion of the outer preform is filled in the hole portion and further covers the outer surface of the bottom portion of the outer preform. Characterized by It is obtained by a two-layer structure preform for stretch blow molding.

Further, in the invention of claim 2, a substantially circular groove or a convex portion is provided on at least one surface inside the periphery of the flange at the upper end of the cylindrical body of the outer preform. 2. The stretch-blown two-layer preform according to claim 1, wherein the resin at the mouth and neck of the inner preform facing the flange is formed so as to cover the flange. is there.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 1, the two-layered preform for stretch blow molding of the present invention comprises a cylindrical body (12) having a flange (16) at the upper end and a bottom (14) at the lower end. A hole (1) is formed at the bottom (14).
8), an outer preform (10) made of a barrier resin molded with a cylindrical body (2) having a mouth-neck portion (26) at an upper end thereof and being in intimate contact with the inner surface of the outer preform (10).
Fig. 2 is a two-layer stretch blow molding preform (1) composed of 2) and an inner preform (20) made of resin for a container body molded with a bottom (24) at the lower end, As shown in FIG. 2A, a substantially circular groove is formed on at least one surface (the outer surface of the bottom portion (14) in the drawing) of the bottom portion (14) near the periphery of the hole portion (18) of the outer preform (10). (14a) or a convex portion (not shown) is provided,
The resin of the inner preform (20) facing the hole (18) of the outer preform (10) is filled with the resin of the hole (1).
8) and is formed so as to cover the outer surface of the bottom portion (14) of the outer preform (10).

The substantially circular groove (14a) formed in the bottom (14) near the periphery of the hole (18) of the outer preform (10) has a bottom (14) as shown in FIG. 2 (b).
2c, and as shown in FIG. 2 (c),
A knurl (14b) in which a plurality of substantially circular grooves and convex portions are alternately formed may be provided on the outer surface or on both surfaces as shown in FIG. 2 (d).

By forming the two-layer preform (1) for stretch blow molding having the shapes of the bottoms (14, 24) of the outer preform (10) and the inner preform (20) as described above, the barrier plastic is formed. At the time of stretch blow molding of a bottle, cracks are generated at the bottom portion (14) of the outer preform (10) stretched by a stretching rod inserted into the two-layered preform (1) for stretch blow molding, or substantially. The circular groove or convex portion exerts a locking function, and there is no deviation or separation from the bottom portion (24) of the inner preform (20).
Thus, the obtained barrier plastic bottle can be made without a decrease in barrier properties or drop strength.

Further, as shown in FIG. 3 (a), at least one surface inside the periphery of the flange portion (16) at the upper end of the cylindrical body of the outer preform (10) (see FIG. The lower surface of the outer preform (1a) is provided with a substantially circular groove (16a) or a convex portion (not shown).
The resin of the mouth and neck portion (26) of the inner preform (20) opposed to the flange portion (16) of (0) is applied to the flange portion (1).
6).

The above substantially circular groove (16a) is provided in FIG.
As shown in (b), the upper and lower surfaces of the flange portion (16) may be used, and as shown in FIG. 3 (c), a knurled eye (16b) in which a plurality of substantially circular grooves and convex portions are alternately formed. 2D may be applied to the lower surface or to both upper and lower surfaces as shown in FIG.

The two-layer stretch blow molding preform (1) having the shape of the flange portion (16) of the outer preform (10) and the mouth and neck portion (26) of the inner preform (20) as described above. Thereby, in the stretch blow molding of the barrier plastic bottle, the substantially circular groove or convex portion exerts a locking function, and the stretched flange portion (16) is attached to the mouth and neck portion (26) of the inner preform. The barrier plastic bottle thus obtained is not displaced or peeled off, and the barrier plastic bottle thus obtained does not cause a decrease in barrier properties or drop strength even in the vicinity of the flange portion (16) of the outer preform (10). Can be.

The outer preform (10) that constitutes the light-shielding barrier packaging material (1) of the present invention is made of a barrier resin that blocks oxygen, water vapor, or ultraviolet rays. For example, polyethylene naphthalate (PEN), ethylene/
Examples thereof include a vinyl alcohol copolymer (EVOH) and meta-xylene diamine (MDX6), which can be appropriately selected depending on the application.

The preparation of the outer preform (10) is as follows.
For example, as shown in FIG. 4, after the heated barrier resin (R) is injected and filled into the cavity (10a) for the outer preform (10) from the resin injection gate (34), the molding die (40) is formed. ) To cool the cavity (10a)
The outer preform (10) is obtained by solidifying the inner barrier resin (R).

In order to form a two-layer preform (1) for stretch blow molding using the outer preform (10), as shown in FIG. 5, a molding die for a two-layer preform for stretch blow molding. The outer preform (10) obtained above is placed in (50), and subsequently heated resin (Y) for container body (polyethylene terephthalate (PE)).
T) is commonly used) a resin injection gate (55)
From the inside of the cavity (50a) and into the hole (18) of the outer preform (10), and further roll-formed so as to cover the outer surface of the bottom (14) of the outer preform (10). Also in the vicinity of the flange portion (16) of 10), it is wound and formed so as to cover the lower surface of the flange portion (16), and then the molding die (50) is cooled to solidify the resin (Y) for the container body in the cavity. Thus, a two-layer preform (1) for stretch blow molding is obtained.

[0019]

As described above, the present invention has the following effects. That is, an outer preform made of a barrier resin and provided with a cylindrical body having a flange at the upper end, a bottom at the lower end, and a hole at the bottom, and a mouth and neck at the upper end. In a two-layer preform for stretch blow molding, which is constituted by a resin-made inner preform for a container body molded with a cylindrical body part and a bottom part at the lower end in close contact with the inner surface of the outer preform, At least one surface of the bottom near the perimeter of the hole of the outer preform is provided with a substantially circular groove or protrusion, and the resin of the inner preform facing the hole of the outer preform is located in the hole. Since it is filled and formed so as to cover the outer surface of the bottom of the outer preform, there is no crack, misalignment or peeling near the bottom when forming the barrier plastic bottle by stretch blow. It is possible to provide a configuration preform.

A substantially circular groove or projection is provided on at least one surface inside the periphery of the flange at the upper end of the cylindrical body of the outer preform, so that the inner side faces the flange of the outer preform. Since the resin of the mouth and neck of the preform is formed so as to cover the flange, when stretch-blown molding of the barrier plastic bottle, the resin for the mouth and neck of the inner preform near the stretched flange is used. It is possible to provide a two-layer preform for stretch blow molding without displacement or peeling.

The barrier plastic bottle thus obtained can be made without a decrease in barrier properties or drop strength near the bottom or flange of the bottle.

Therefore, the present invention stores drinks and the like,
As a two-layer stretch blow molding preform for a barrier plastic bottle that blocks oxygen, water vapor or ultraviolet rays, it exhibits excellent practical effects.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a two-layered preform for stretch blow molding of the present invention in a side cross section.

FIG. 2 is an enlarged view illustrating an example of the bottom shape of a two-layer preform for stretch blow molding according to the present invention.
(B) shows a substantially circular groove formed on the bottom surface of the outer preform, and (b) shows a substantially circular groove formed on both bottom surfaces of the outer preform. (C) is a knurled lower surface of the outer preform,
(D) is obtained by applying knurling to both bottom surfaces of the outer preform.

FIG. 3 is an enlarged view for explaining an example of a flange shape of a two-layer preform for stretch blow molding of the present invention.
(A) is a case where a substantially circular groove is formed on the lower surface of the flange portion of the outer preform, and (b) is a case where a substantially circular groove is formed on both surfaces of the flange portion of the outer preform. (C)
(D) is a case where knurling is applied to the lower surface of the flange portion of the outer preform, and (d) is a case where knurling is applied to both surfaces of the flange portion of the outer preform.

FIG. 4 is an explanatory view showing an example of molding of an outer preform constituting a two-layer preform for stretch blow molding of the present invention in a side cross section.

FIG. 5 is an explanatory view showing an example of molding of a two-layer preform for stretch blow molding of the present invention in a side cross section.

FIG. 6 is an explanatory view showing an example of a conventional two-layer preform for stretch blow molding in a side cross section.

FIG. 7 is an explanatory view showing, in a side cross section, an example of stretch blow molding using a conventional two-layer stretch preform for stretch blow molding.

[Explanation of symbols]

1 ‥‥ Preform having a two-layer structure for stretch blow molding 10 ‥‥ Outside preform 12 ‥‥ Body of outside preform 14 ‥‥ Bottom of outside preform 14a ‥‥ Substantially circular groove at bottom 14b ‥‥ Knurl at bottom 16 ‥‥ Flange portion of outer preform 16a ‥‥ Substantially circular groove of flange portion 16b ‥‥ Knurled portion of fwange portion 18 ‥‥ Hole portion of outer preform bottom 20 ‥‥ Inner preform 22 ‥‥ Inner preform Body 24 ‥‥ Bottom of inner preform 26 ‥‥ Mouth and neck of inner preform 34 ‥‥ Gate for injection of barrier resin 40 ‥‥ Molding die for outer preform 50 ‥‥ Two-layer structure for stretch blow molding Reforming mold 50a {double-layer preform cavity for stretch blow molding 55} resin injection gate for container body 56} core Body 70 ‥‥ Stretched rod R ‥‥ Barrier resin Y ‥‥ Container body resin V ‥‥ Blow pressure direction

Continued on the front page F term (reference) 3E033 AA20 BA18 BB08 CA16 DA03 DA08 FA02 FA03 4F202 AA24 AG03 AG07 AG23 AG24 AH55 CA11 CA15 CB22 CK11 CK81 4F208 AA24 AG03 AG07 AG23 AG24 AH55 LA04 LA08 LB22 LG15 LG16 LG19 LG29 LN

Claims (2)

[Claims] 1. An outer preform made of a barrier resin and having a cylindrical body having a flange at the upper end, a bottom at the lower end, and a hole provided at the bottom, and a mouth and neck at the upper end. A two-layer stretch blow molding mold comprising a cylindrical body part closely attached to the inner surface of the outer preform and a resin inner preform for the container body molded with a bottom part at the lower end. In the reforming, a substantially circular groove or a convex portion is provided on at least one surface of the bottom near the perimeter of the outer preform, and the resin of the inner preform facing the perforated portion of the outer preform is provided. A two-layered preform for stretch blow molding, wherein the preform is formed so as to be filled in the perforated portion and to cover an outer surface of a bottom portion of the outer preform. 2. A substantially circular groove or convex portion is provided on at least one surface inside a periphery of a flange portion at an upper end of a cylindrical body portion of the outer preform, and an inner side opposed to the flange portion of the outer preform. 2. The stretch blow molding two-layer preform according to claim 1, wherein the resin at the mouth and neck of the preform is formed so as to cover the flange.