JPS585232A - Method of forming biaxially oriented bottle of synthetic resin - Google Patents

Abstract

PURPOSE:To produce a bottle economically, by clamping a parison, whose upper part is heated to 150-230 deg.C, in molds, pushing down the parison bottom wall by an oriented rod, and biaxially orientating the parison across it and at the same time forming a threaded section to the parison. CONSTITUTION:The upper part of the parison is heated to 150-230 deg.C, and is clamped in the molds. By pushing down the oriented rod 8 into the parison, it is longitudinally orientated. Then compressed air is blown into the parison to orientate it transversely. simultaneously with the orientation, pressure is applied to the inner surfaces of the bottle neck and the shoulder adjacent to the base of the bottle neck to make them forcibly in contact with the inner surfaces of the molds so that a cap threaded section 11 is formed. After cooling, the biaxially oriented bottle 12 is taken out from the molds.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the production of biaxially stretched synthetic resin bottles, particularly biaxially stretched bottles with screw-on caps for filling high-temperature liquids and filling liquids whose internal pressure increases when sealed. Regarding the method. Biaxially stretched bottles tend to have residual strain due to stretching, so when filled with high temperature liquid, they shrink, resulting in a reduction in grain size. Heat fixing is performed to remove these defects, but it is difficult to heat fix the neck of the bottle and the shoulder near the proximal end of the neck.
In addition, in the case of a bottle in which a screw for screwing the cap is formed on the neck of the bottle, heat setting after forming the bottle is time-consuming, troublesome, and costly.

The present invention eliminates the above-mentioned drawbacks, and will be explained below with reference to the drawings. 1.1 is a mold for molding the outside peripheral surface having a cavity 2.2, and 3 is a mold for molding an additional bottom wall portion. . At least one of the molds 1.1 is movable in the horizontal direction and is capable of closing and opening the mold. The upper part of the mold 1.1 is formed into parts 1a, 1a which form the entire neck and neck of the bottle, and the inner surface of the mold 1.1 is a capitivity part which forms the neck with a thread for screwing the cap. From the mold 3, the rod passes through the entire mold, and by clamping the molds 1 and 1, the central axis of the rod passes on the central axis of the one-shaped space formed by the cavity, and the rod passes into the space. It is preferable that the eccentricity prevention rod 4 protrudes so as to be able to be moved in and out.

When forming a biaxially stretched bottle, a cylindrical parison 7 with a closed bottom end is vertically placed in the space formed by the cavity of the mold. The parison has a mouth and neck forming part 1a at the upper part of the parison.
, la to hang it vertically. The parison is heated to a temperature suitable for biaxial stretching, and especially the upper part, which is held between the molds, is heated to about 150'O to 230'O. The heating is performed by heating the upper outer surface with a mold,
This may be done within the mold by applying suitable means to the inner surface of the upper part, or may be done prior to installation into the mold.

When the upper bar 4 is provided by inserting the stretching rod 8 into the parison, the upper part of the parison is sandwiched between the upper end surface of the rod and the upper end surface of the stretching rod, and while maintaining the clamped state, rod? By lowering them together, they can be extended as shown in FIG. After stretching in this manner, or during stretching, compressed air is blown into the parison to stretch it in the transverse direction. Compressed air may be blown into the parison after the extension rod is removed, or with the extension rod inserted, from between the outer peripheral surface of the extension rod and the inner surface of the upper end of the parison. All compressed air introduction lines 9 are provided on the rod, and all of the introduction paths can be utilized.

Furthermore, after or at the same time as the stretching, internal pressure is applied to the inner surface of the first neck part and one shoulder part adjacent to the proximal end of the neck part, and the cap screw is attached to the outer surface of the neck part 10 by press-contacting it to the inner surface of the mold. A mating threaded portion 11 is formed. The inner surface can be pressurized using hydraulic pressure, air pressure, or the like.

After the above-described threaded portion is formed, the neck and neck portion and the shoulder portion adjacent to the proximal end of the neck and mouth are cooled, and then the biaxially stretched bottle 12 is removed from the mold.

The method of the present invention is carried out as described above, and starts with about 1
Since the biaxially stretched bottle is completely formed using a parison whose upper part is heated to 50°C to 230°C, even if the parison is filled with boiling liquid, the neck and neck part and the adjacent shoulder part at the proximal end will not shrink due to heat. (other parts are heat-set by a well-known appropriate method), the upper part is heated to the above temperature and then biaxially stretched, and the shoulder of the bottle close to the widening neck and the base of the neck The parts are pressed against the inner surface of the mold, and a threaded part for screwing the cap is formed on the white neck by this pressure-welding. Therefore, the entire threaded part is formed on the upper outer surface of the parison in advance, and the parison with the threaded part is mounted on two shafts. Compared to the case of a stretched bottle, the threaded portion 11 can be formed at the same time as heat setting, and the threaded portion can also be formed using heating for heat setting, so it can be done easily and quickly. can be achieved, and the cost can also be reduced.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the parison suspended in the mold, Fig. 2 is a cross-sectional view showing the parison stretched in the longitudinal axis direction, and Fig. 3 is a cross-sectional view showing the parison stretched in the longitudinal direction. It is a sectional view showing a state made into an axially stretched bottle. 1... Mold for molding the outside peripheral surface 2... Capity 3
...Mold for forming the bottom wall part 7...Cavity 8.
...Stretching rod 11...Threaded part 12...Biaxially stretched bottle

Claims (1)

[Claims] The upper part is heated to about 150' to 230' C and the upper part is held between the threaded mouth and neck forming part of the mold, so that the cavity of the mold forms a cylindrical parison with the lower end closed. The parison is suspended in the space and stretched in the longitudinal direction by pressing down a stretching rod inserted into the parison, and compressed air is blown into the parison at the same time as or after the stretching in the longitudinal direction. An axially stretched bottle is formed, and a threaded part of the neck part is formed by press-contacting the one neck part and one scrap part close to the proximal end of the neck part to the inner surface of the mold by applying internal pressure by an appropriate means. A method for forming a luniaxially stretched synthetic resin bottle, which comprises cooling the mouth and neck portion and the shoulder portion adjacent to the proximal end of the portion, and then removing the bottle from the mold.