JPH074849B2 - Laminated container manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a synthetic resin container having an excellent gas barrier property.

[Conventional technology]

Conventional synthetic resin containers are often biaxially stretch blow molded because of their improved mechanical strength, heat resistance, and gas barrier properties.

However, internal residual stress is generated in the container molded by these biaxially stretched blows, so that there is a problem that the finished container is contracted and deformed. There is a molding method called double blow that solves this problem.
In this double blow molding, the biaxially stretched blow molded container is heated again to remove the internal residual stress existing in the container, and then blown again to obtain a finished product. As a result, the container formed by the double blow is less likely to shrink and deform than the container formed by simply biaxially stretching.

[Problems to be solved by the invention]

However, even with this conventional synthetic resin container that is difficult to shrink and deform, its gas barrier property cannot be said to be sufficiently satisfactory. In particular, when storing drinking water containing carbon dioxide gas, a gas barrier property superior to that is required.

The present invention has been conceived in view of this point, and an object of the present invention is to further improve the gas barrier property of the conventional double blow molded container.

[Means for solving problems]

Therefore, in the double blow molding process in which the residual stress is removed by reheating after biaxial stretch blow molding, and then reblowing is performed to obtain a finished product, before the biaxial stretch molding is blown and before the reblowing is performed. The container 2 was covered with a heat-shrinkable bag body 3 having an excellent gas barrier property, and the bag body 3 was brought into close contact with the outer surface of the container 2.

[Action]

Since the bag body 3 that covers the container 2 is heat-shrinkable, the bag body 3 shrinks due to the heat when the container 2 is reheated, and adheres to the outer surface of the container 2. With the bag body 3 in close contact with the outer surface of the container 2,
When re-blowing is performed, the container 2 swells slightly, so that the close contact between the bag body 3 and the outer surface of the container 2 becomes more dense.

〔Example〕

 Embodiments according to the present invention will be described below.

FIG. 1 shows a container 2 made of polyethylene terephthalate resin which has been biaxially stretch blow molded. This container 2
Then, as shown in FIG. 2, the bag body 3 is covered. Next, as shown in FIG. 3, the assembly of the bag body 3 and the container 2 is reheated.
By this reheating, the internal residual stress generated in the container 2 is removed, and the heat-shrinkable bag body 3 contracts and adheres to the outer surface of the container 2. Further, the re-blowing shown in FIG. 4 causes the container 2 to slightly swell, and the close contact between the container 2 and the bag body 3 is further increased.
The laminated container 1 which is an integrated product is completed.

5 to 8 show another manufacturing method.
In this manufacturing method, FIG. 5 shows the biaxially stretch blow-molded container 2, and FIG. 6 shows the reheated state. As shown in FIG. 7, the bag 3 is placed in the reheated container 2.
When the bag 3 is covered, the bag 3 comes into close contact with the outer surface of the container 2 while being contracted by the heat of the container 2 and becoming soft. From this state,
As shown in FIG. 8, when re-blowing is performed, the container 2 swells slightly, and the close contact between the container 2 and the bag body 3 is further strengthened.

〔The invention's effect〕

As described above, according to the present invention, a gas-barrier property superior to that of the conventional biaxially stretched blow molding container or the double-blowing molding container can be easily achieved by only covering the heat-shrinkable bag having good gas barrier property during the double-blowing process. It is possible to provide a laminated container having a laminated structure.

[Brief description of drawings]

1 to 4 show one embodiment, FIG. 1 shows a state after biaxial stretch blow molding, and FIG. 2 shows a state in which a bag is covered,
FIG. 4 is a sectional view showing a state of reheating, and FIG. 4 is a state of reblowing. FIGS. 5 to 8 show another embodiment. FIG. 5 shows after biaxial stretch blow molding, FIG. 6 shows reheating, FIG. 7 shows after covering with a bag, and FIG. 8 shows again. It is sectional drawing which shows the state of blow. Explanation of reference numerals 1: laminated container, 2: container, 3: bag body.

Claims (1)

[Claims] 1. In a double blow molding step of reheating after biaxial stretch blow molding to remove residual stress and then reblowing to obtain a finished product, the biaxial stretch molding is blown and the reblowing is performed. A laminated container (1) in which a container (2) before being covered is covered with a heat-shrinkable bag (3) having an excellent gas barrier property, and the bag (3) is brought into close contact with the outer surface of the container (2). Production method.