JPS6017693B2 - Polyethylene terephthalate resin bottle and molding method for this bottle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an eel body made of polyethylene terephthalate resin and a method for molding this continuous body.
After injection molding into a straight cylindrical piece with a bottom, this piece is biaxially stretched and blow molded to form a polyethylene terephthalate resin dust body. By not forming threads on the piece, it is possible to make individual pieces from a single mold. The purpose is to compensate for the lack of mechanical strength of the capital, which is rarely biaxially stretched, and to prevent deterioration of the appearance of the neck, which is sometimes prone to whitening, from the outside.

Another object is to easily and reliably achieve the desired assembly of the screw member and the main body 1 by biaxially stretching the screw member as part of a molding die.

Polyethylene terephthalate resin has excellent transparency, a glossy surface, excellent gas barrier properties against oxygen and carbon dioxide, and does not contain additives such as plasticizers or stabilizers, so it is suitable for hygiene purposes. There are no problems and it is highly safe.
It has many excellent properties such as excellent content resistance and aroma retention, no toxic gas is generated during combustion, and low combustion heat, but on the other hand, it has an extremely low viscosity when melted. It is extremely difficult to mold because it becomes cloudy when stretched nearby, does not exhibit sufficient mechanical strength unless biaxially stretched, and turns white when exposed to alcohol, etc., further deteriorating its transparency properties. It became.

Molding of molded articles using polyethylene terephthalate resin is greatly limited by the properties of the polyethylene terephthalate resin described above, and injection blow molding is the most suitable molding method. To briefly explain this injection blow molding method, first, a piece as a primary molded product is formed by injection molding (injection molding), and when the temperature of this piece is cooled to a temperature suitable for blow molding. Then, the pieces are biaxially stretched and blown to form the final product.

By the way, in order to form a screw on the outer circumferential surface of the neck of a polyethylene terephthalate resin body molded by injection molding, it is necessary to mold the neck of the piece to be injection molded at the same time as the molding of the piece. There are two methods: a method of keeping the pieces in place, and a method of forming the neck part by blow molding during blow molding, but the method of molding a screw on the neck part of the piece reduces the number of individual pieces in a single mold. In addition, the structure of the mold device for molding the piece is complicated, making it difficult to handle, and the thickness of the piece varies locally, making temperature control (cooling operation) difficult.
In addition, forming a screw on the neck by blow molding the piece requires an extremely high blow pressure to form the screw, which makes the pressure source uneconomical. Since the mold equipment must be able to handle this pressure, the mold equipment is quite large for the molded product, and even if the blowing pressure is increased, the screws cannot always be molded accurately and reliably. However, it has drawbacks such as an increased incidence of defective products.

The present invention was devised to eliminate all of the above-mentioned problems with polyethylene terephthalate resin bodies having screws in the capital. A cylindrical screw thread made of a suitable synthetic resin other than polyethylene terephthalate resin or metal is attached to the capital of the ethylene terephthalate resin body in a circumferential direction to prevent it from idling. The present invention relates to a method for forming this mackerel body more easily.

Hereinafter, the present invention will be explained with reference to the drawings showing embodiments.

The crab body according to the present invention (see FIG. 1 below) consists of a main body 1 obtained by stretch-blow molding a piece 1', and a neck l of this main body 1.
It consists of a screw member 2 fixed to b to prevent it from idling.

The main body 1 has a slightly thick mouth edge part lc that protrudes outward and serves as a base for fixing the piece 1' to a mold device when the piece 1' is stretched in two balls, and a mouth edge part lc below this mouth rim part lc. It is composed of a capital lb which is the paper attachment part of the screw member 2 connected to the body 1, and a biaxially stretched chest la which forms the main part of the main body 1 as a container. It is stretched in the radial direction, but not necessarily in the radial direction.

The screw member 2, which is fixed to the neck portion lb of the main body 1 with iron fittings while being locked in the central direction, is made of a synthetic resin other than polyethylene terephthalate resin or metal, and has a height equal to the neck portion lb. It has a cylindrical shape with a thread 2a formed on its outer peripheral surface.

The inner diameter of this screw member 2 is not larger than the outer diameter of the neck portion lb of the piece 1' having a straight cylindrical shape with a bottom.

Molding of the continuous body having such a structure is performed in the following order.

(See Figures 2 and 3 below) A cylindrical screw member is inserted from the bottom side of a piece 1' made of polyethylene terephthalate resin, which has a bottomed straight cylindrical shape and has a rim lc on the outer periphery of the mouth. 2 is attached to the main body of piece 1' until it hits the mouth edge lc.

This assembly of the screw member 2 to the piece 1' may be performed after the piece 1' is attached to the mold device, or after the assembly of the screw member 2 to the piece 1'. The combination of piece 1' and screw member 2 may be attached to the mold cap.

In this way, after the piece 1' to which the screw member 2 has been roughly attached is roughly attached to the mold device by the tread portion lc or via the screw member 2, the piece 1' is roughly attached to the screw member 2 by the mold device. In this state, the main body 1 is formed by two-way stretch molding, and a mackerel body is formed. That is, the attachment of the screw member 2 to the main body 1 in an irremovable manner is achieved by two-wheel stretch-forming of the piece 1' onto the main body 1.

There are various means for narrowing the screw member 2 relative to the main body 1 in a state where it is locked in the circumferential direction to prevent it from idling.Next, a representative one of these means will be explained.

The first method (see Fig. 4) is to provide a desired number of vertical grooves 2b on the inner circumferential surface of the threaded part 2, and then attach the threaded member 2 to the outer circumferential surface of the neck part 1b of the piece 1'. Vertical groove 2 when iron-clad
It has a structure in which a vertical groove lb' is provided which fits perfectly into the groove b.

In this structure, the inner diameter of the screw member 2 is approximately equal to the outer diameter of the neck lb' of the piece 1', and the screw member 2 is iron-clad to the piece 1', and the vertical groove 2b and the vertical strip lb' are It is better to make sure that they match each other.

Second, (see Figs. 5 and 6), a recess 2c having a substantially longitudinal groove shape is formed on the inner circumferential surface of the threaded portion 2, and the neck portion lb also has a radius of It has a structure in which a part of the neck portion lb is depressed into the concave portion 2c by stretching in the direction of the neck portion 2c.

In the case of this structure, the inner diameter of the screw member 2 is preferably made larger to some extent than the outer diameter of the capital lb of the piece 1'.

This is because when the piece 1' is stretched biaxially, the neck lb of the piece 1' is also biaxially stretched like the other parts because the screw member 2 is not in contact with the neck lb of the piece 1'. This is because the mechanical strength increases.

Thirdly, (see Fig. 7), the lower end edge 2d of the screw member 2 is made into a waveform shape that is uneven up and down, and when the piece 1' is stretch-molded using the screw member 2 as part of the mold, Torso l
The connecting base of the chest part a with the capital lb is formed along this lower edge 2d, and the connecting base of the chest la with the capital lb is meshed with the corrugated lower edge 2d.

In the case of this structure, it does not matter at all whether the inner diameter of the screw member 2 is equal to or larger than the outer diameter of the neck lb of the piece 1', that is, whether the neck lb is stretch-molded or not. The part of the main body 1 that engages with the green 2d is the base end of the connection with the neck part lb of the body part la, which is biaxially stretched and given sufficient mechanical strength, so that the screw member 2 does not slip with respect to the main body 1. The impossible rope attachment power becomes powerful.

It goes without saying that the thickness of the screw member 2 is equal to or greater than the amount of outward protrusion of the rim portion lc. Furthermore, compared to the structure shown in Fig. 4, the structure shown in Figs. Since it is stretch-molded, it exhibits excellent effects in terms of the mechanical strength of the bell body.

Furthermore, although the structure shown in FIG. 7 has a continuous wave shape in the case of the illustrated embodiment, the unevenness of the lower end green 2d does not necessarily have to be a continuous wave shape, but can be formed in a desired number. All that is required is to form the concave portions or convex portions appropriately. However, the concave or convex portion must be formed with a sufficiently rounded structure.

As is clear from the above description, the present invention has a structure in which a screw member 2 molded from an appropriate material is attached to the neck portion lb of a biaxially stretch-molded main body 1 made of polyethylene terephthalate resin. Since it is not necessary to form a screw on the outer peripheral surface of the neck portion 1' of the piece 1' or to form a screw on the neck portion 1b by biaxial stretching molding of the piece 1', the molding operation of the piece 1' and the body 1 is extremely simple. 2. Since the screw is not directly molded on the neck part lb, which cannot be said to have sufficient mechanical strength because it is not stretch-molded, a strong screw connection can be obtained without damaging the main body 1, and the transparency is lower than that of the chest la. Since the inferior neck part lb is hidden by the screw member 2, deterioration of the appearance of the crab body can be prevented, and a large number of pieces 1' can be molded with a single mold, and the material of the screw member 2 can be can be selected completely freely, and there are many excellent effects regarding the polyethylene terephthalate resin moat body, such as biaxial stretching of the piece 1' and simultaneous roughening of the screw part 2 to the main body 1 that cannot be separated. It has the following.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing an example of the structure of a foot body made of polyethylene terephthalate resin according to the present invention, and FIGS. 2 and 3 are longitudinal cross-sectional views of main parts showing some steps of the molding order of the bell body. In the figures, FIG. 2 shows the state of the screw member before it is attached to the piece, and FIG. 3 shows the state of the screw member being assembled to the piece. Figures 4 to 7 are diagrams showing a structure in which the neck of a screw member is roughened to prevent slippage. Figure 4 shows a structure in which a protrusion is provided at the capital of the piece in a vertical groove cut into the inner circumferential surface of the screw member. Figures 5 and 6 are cross-sectional views of the main parts in the case of a structure in which vertical strips are interlocked, and Figs. In the top views, FIG. 5 shows the neck before stretching and FIG. 6 shows the capital after stretching. 7th
The figure is a front view of a main part of a structure in which unevenness is formed on the lower edge of the screw member and a part of the main body is engaged with the unevenness. Explanation of symbols 1: Main body, 1'; Piece, la; Body, -lb; Neck, lc; Mouth rim, 2; Thread member, 2a; Thread, 2b;
Vertical groove, 2c; recess, 2d; lower edge. / / 2 thorns, 3 sardines? 4th dan Liu Nogaku 2 poems 6 shoes are fu ■

Claims (1)

[Scope of Claims] 1. In the neck portion 1b formed between the body portion 1a which is biaxially stretch blow molded of the main body 1 made of polyethylene terephthalate resin and the mouth edge portion 1c which becomes slightly thicker and protrudes outward. , a screw member 2 made of a synthetic resin other than polyethylene terephthalate resin or metal, which is a cylindrical body having the same height as the neck portion 1b and has a thread 2a formed on its outer peripheral surface, is fitted in a state in which it is locked in the circumferential direction. A bottle made of polyethylene terephthalate resin. 2 Desired number of vertical grooves 2b formed on the inner peripheral surface of the screw member 2
A bottle according to claim 1, wherein a vertical strip 1b' formed on the outer circumferential surface of the neck portion 1b is fitted so that a screw member 2 is attached to the main body 1 so as to be prevented from idling. 3. A patent claim in which the screw member 2 is assembled to the main body 1 so as not to be idly rotated by fitting a part of the neck portion 1b into a desired number of vertical groove-like recesses 2c formed on the inner circumferential surface of the screw member 2 by blow molding. Bottle shown in range 1. 4 Patent for assembling the screw member 2 to the main body 1 so as not to rotate by blow molding the lower end edge 2d of the screw member 2 formed with corrugated irregularities to fit the connecting base with the neck portion 1b of the body portion 1a by blow molding. The bottle shown in claim 1. 5. After fitting the screw member 2 into the bottomed straight cylindrical piece 1' which is formed into the main body 1 by biaxial stretch blowing in such a manner that it abuts against the mouth edge 1c of the piece 1', A method for molding a polyethylene terephthalate resin bottle body, in which a screw member 2 is used as part of a mold and a piece 1' is biaxially stretch blow molded onto a main body 1.