JPS5949892B2 - Mouth and neck stretching method for saturated polyester resin bottles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for stretching the neck and neck of a bottle made of saturated poly9ester resin.

Saturated polyester resin bottles have advantages over other synthetic resin bottles in that they do not exude solvents and do not emit toxic gas when incinerated after disposal, but they have the disadvantage that they are easily broken unless biaxially stretched. It was hot.

Biaxial stretching of the main part of the bottle, excluding the mouth and neck, the grip body, the bottom wall, and the shoulders, is carried out by blowing high-pressure air into the bottle, and at the same time, pushing it down in the longitudinal direction. This is done by pushing down the bottom wall with a rod, but currently the mouth and neck are not stretched biaxially. However, it is natural that it is desirable to biaxially stretch the neck of the bottle as well, and the method of the present invention aims to easily and reliably stretch the neck of the bottle, thereby improving its mechanical properties. Referring to the drawings below, reference numeral 1 denotes a tubular intermediate material made of saturated polyester resin that has been injection molded in advance.

Both the upper and lower ends are open, but the inner diameter of the upper part, the mouth and neck part 2, is smaller than that of the body part 4, which is suspended vertically through the shoulder part 3, and the shoulder part 3 has a tapered shape that expands downward. It is formed into a shape. In the next step, the tubular material 1 is heated up to its neck and shoulder portions to a temperature of approximately 100°C, which is suitable for stretching, and while maintaining this temperature, a rod-shaped jig 6 is inserted into the tube hole 5 from below. The mouth and neck part 2 is stretched by passing through the mouth and neck part 2. The rod-shaped jig has an outer diameter of the upper part T smaller than the inner diameter of the mouth and neck part 2, and an outer diameter of the lower part 8 smaller than the inner diameter of the body part of the intermediate material and larger than the inner diameter of the diameter part. Between the upper and lower parts is a tapered part 9 that expands downward. In the next step, the lower end of the body of the tubular material is heated, and the mold 10 is heated.
The bottom wall portion 4a is formed by using the lower end of the above-mentioned rod-shaped jig.

The bottom wall portion may be formed by closing the lower end of the body by pinching it, etc., and then crimping it between the lower end of the jig and the mold, or by welding a separate material having a bottom wall to the lower end of the body. You may let them. After forming the intermediate material '1 having the bottom wall part 4a as described above, it is heated, transferred into a blow mold, and its body part and bottom wall part are biaxially stretched, forming a bottle. 11 is formed.

The method of the present invention is carried out as described above, in which a pipe-shaped intermediate material is prepared in advance with openings at both ends and the mouth and neck have a smaller inner diameter than the body, and the inside of the pipe hole is made larger than the inner diameter of the bore. Since the diameter portion is stretched by inserting and passing a rod-shaped jig having an outer diameter from the lower end of the intermediate material, the stretching is extremely easy, and the structure of the jig can be extremely simple.

Furthermore, since the caliber is stretched in this manner, cracks that tend to occur around the mouth can be reliably prevented, making it possible to easily produce a bottle with excellent mechanical strength throughout the bottle.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the intermediate material, FIG. 2 is a cross-sectional view showing a method of stretching the mouth and neck, FIG. 3 is a cross-sectional view showing a method of closing the lower end of the intermediate material to form a bottom wall, and FIG. 1 is a cross-sectional view of a saturated polyester resin bottle molded by the method of the present invention. 1... Intermediate material, 2... Mouth and neck area, 3... Shoulder area,
4...Body part, 4a...Bottom wall part, 5...Pipe hole, 6.
... Bar-shaped jig, 1... Upper part (of the jig), 8... Lower part (of the jig), 11... Bottle.

Claims (1)

[Claims] 1. Prepare in advance a tubular intermediate material made of saturated polyester resin with openings at both ends and the neck and mouth having a smaller inner diameter than the body.
With the mouth and neck kept at a temperature suitable for stretching, the upper part has an outer diameter smaller than the inner diameter of the mouth and neck, and the upper part has an outer diameter smaller than the inner diameter of the body and larger than the inner diameter of the mouth and neck. Insert the upper part of the rod-shaped jig into the lower end opening of the intermediate material, pull it upward, and let it pass through the lower part to stretch the neck and neck of the intermediate material.In the next step, the lower end of the intermediate material is welded. 1. A method for stretching the neck and neck of a bottle made of saturated polyester resin, which comprises stretching the bottle to form a bottom wall and biaxially stretching a portion other than the neck and neck.