JPS6030168Y2 - Polyethylene terephthalate resin bottle - Google Patents

Description

[Detailed description of the invention] The present invention relates to a polyethylene terephthalate resin ring, which requires increased mechanical strength and high transparency at the bottom of the polyethylene terephthalate resin ring that is biaxially stretched and blow-shaped. This is to prevent deterioration of the appearance of the polyethylene terephthalate resin ring body due to runner cutting, for which appearance is important, and to prevent dust from accumulating on the underside of the bottom of the weir body. The purpose is to make it easy to remove trash etc.

Polyethylene terephthalate resin has extremely high transparency, a photo-selectable surface, excellent gas barrier properties against oxygen and carbon dioxide, and does not contain additives such as plasticizers or stabilizers, making it hygienic. It has many excellent properties, such as being safe without the above disadvantages, producing no toxic gas when burned, and having a low combustion heat, but on the other hand, when melted, it has an extremely low viscosity. , Celsius 1
This is because it becomes cloudy when slowly cooled around 40 degrees, does not exhibit sufficient mechanical strength and deteriorates in transparency unless it is biaxially stretched, and furthermore, it turns white when exposed to alcohol, etc. The molding method has generally been limited to a method in which a piece that has been injection molded in the shape of a bottomed cylinder is reheated to a temperature at which a stretching effect can be obtained, and then biaxially stretched and blown.

In the above-mentioned biaxial stretching blowing process of polyethylene terephthalate resin, biaxial stretching gives the molded product sufficient mechanical strength, high transparency, and stable physical properties.
This is done during the blow molding operation.

In this way, the polyethylene terephthalate resin weir body is ultimately formed into a biaxial stretch blow molding, but the piece as the primary molded product to be biaxially stretch blow molded is injection molded.

Due to the temperature characteristics of polyethylene terephthalate resin, in which the injection molded piece becomes cloudy when slowly cooled to around 140 degrees Celsius, there are various difficult temperature control problems during molding, especially when it comes to lunch. The bottom part, which is the connection part with the resin, is the most difficult part to prevent clouding due to slow cooling because the flow of resin is intense, the injection output acts directly on it, and it is located closest to the high temperature nozzle. There is.

As a means to more reliably prevent clouding at the bottom, where cloudiness is most likely to occur, the wall thickness of the bottom is thinner than that of the other body parts so that it can easily receive the cooling power from the mold equipment. I'm doing it.

In this way, the bottom of the piece is molded thinner than other parts, and since the bottom of the piece is stretched in contact with the tip of the stretching pin, it is sufficient for frictional resistance with the stretching pin. Not subject to severe stretching.

Therefore, in many cases, the mechanical strength of the bottom part of the molded product was not necessarily sufficient.

In addition, the piece is reheated to a temperature that produces a stretching effect prior to biaxial stretching blow shaping, but each part of the reheated piece often cannot have a uniform temperature, and there is a slight difference between each part. However, due to the temperature difference, there is a drawback that the center point of the stretching may shift from the tip of the stretching pin during biaxial stretching blow shaping, resulting in deflection of the molded product.

In order to eliminate the above-mentioned drawbacks of the conventional example, the mechanical strength of the bottom is reinforced by providing a low-height holding piece protruding from the center of the lower surface of the bottom, and this holding piece is installed in the mold device in a non-displaceable manner. It is conceivable that the occurrence of deflection can be prevented by attaching it.

However, in this way, the retaining piece is cut out from the launch and protrudes from the bottom of the weir body, which is unsightly for a weir body made of polyethylene terephthalate resin, where appearance is important.

Moreover, if the holding piece is angular, it may cause problems such as getting caught in the hand.

At the same time, dirt and the like that have accumulated on the substantially perpendicular connection between the holding piece and the lower surface of the bottom of the body tend to remain attached, and the ring body tends to become unclean if the dirt that has once adhered is removed.

The present application has been devised to eliminate such inconveniences, and one embodiment thereof will be described below with reference to the drawings.

Weir body made of polyethylene terephthalate resin according to the present invention 1
(See FIG. 1) is formed by biaxial stretching blow molding, and has a holding piece 4 protruding from the center of the lower surface of the bottom part 3.

The ring body 1 is composed of a main body part 2 including a trunk part and a neck part, and a bottom part 3, and the bottom part 3 has a gentle curve.
The central part is raised in the shape of a truncated cone with a crested plate, and a spherical plate-shaped holding piece 4, which is smaller than a hemisphere and has a protruding height lower than the rising height of the central part, is protruded from the center of the lower surface of the central part. The connected part between the piece and the lower surface of the bottom is a curved surface.

It is desirable that the size of this holding piece 4 is as large as possible in relation to the thickness of the runner, which will be described later. is disadvantageous in terms of molding and economy.

For this reason, it is recommended that piece 1', which is the primary molded product of ring body 1, be injection molded with a sufficiently thick lunch, and that when the runner connected to piece 1' is removed, a portion of the lunch will remain. This is extremely advantageous in shaping the piece 1' and the holding piece 4.

That is, in order to protrude the holding piece 4, it is necessary to mold the mold surface part for shaping the holding piece 4 into the injection mold of the piece 1'. Forming a new mold surface part for the holding piece 4J and shape on the molding die not only requires a lot of effort in making the mold, but also reduces the substantial wall thickness at the bottom 3' of the piece 1'. As a result, the bottom portion 3' from which the holding piece 4 protrudes becomes more likely to become cloudy.

On the other hand, if the runner is made sufficiently thick during injection molding of piece 1', and the connecting end of this launch to the bottom part 3' is left on piece 1' and cut to form a holding piece, piece 1
It is not necessary to form a special mold surface part for the four holding pieces in the injection mold of ', and injection pressure can be lowered by injecting piece 1' with a sufficiently thick launch like this. This also makes it possible to suppress the intensity of the flow of the polyethylene terephthalate resin at the connection part between the launch and the injection space of piece 1', which is extremely effective in preventing the occurrence of cloudiness in this part.

Furthermore, the holding piece 4 is formed by the necessary operation of cutting out the runner from the piece 1', which is advantageous in terms of manufacturing process and economy.

However, the holding piece 4 that is formed by simply being cut from the runner as described above has an angular projecting end.
Not only is it unfavorable in appearance, but it also feels bad to the touch, and it is easy for dirt and the like to remain attached to the angular connection between the lower surface of the bottom of the fuselage and the holding piece.

Therefore, in the present invention, as shown in Fig. 1, we draw a gentle line in the center of the lower surface of the structure bottom 3 that rises in the shape of a truncated cone, and from a hemisphere at a height that does not exceed the rising height of the bottom 3. A small spherical arc-shaped holding piece 4 is provided protrudingly, and the connecting portion of the holding piece 4 and the lower surface of the bottom is curved.

The weir body 1 having such a structure is biaxially stretched and blow-shaped using a blow mold device as shown in FIG.

That is, the biaxial stretch blow mold device for molding the weir body 1 draws a gentle curve of the bottom mold 7, which forms the mold surface in combination with the split molds 6, 6, and stands up in the shape of a truncated cone. A fitting hole 8 for a holding piece 4 projecting from the piece 1' is formed by cutting a hole 8 on the mold surface opposite to the tip of the elongated pin 5 in the center of the piece 1'.

This fitting hole 8 has a spherical dish shape smaller than a hemisphere and is connected to the center of the upper surface of the bottom mold 7 by a gently curved surface.
It is pressed into this fitting hole 8 and formed into the final shape described above.

It is also conceivable to form the shape of the holding piece 4 of the piece 1' in advance before performing stretch blow molding after forming the piece 1'.

(See Fig. 3) That is, after injection molding of piece 1', which is the primary molded product of weir body 1, the ball of holding piece 4 is attached to the holding piece (see Fig. 3a), which is molded with a part of the launch remaining. The fitting hole 8' of the mold 7' having an arcuate fitting hole 8' is pressed (FIG. 3b) to form the holding piece 4 of the piece 1' as shown in FIG. 3C.

By doing so, the shape of the holding piece can be molded.

As is clear from the above description, the present invention has a weir body made of polyethylene terephthalate resin that is biaxially stretched and blow-shaped, and the holding piece on the bottom of the weir body, which is an essential element during molding, is shaped as described above. It can be formed into.

In the present invention, since the holding piece is not angular, it has an extremely excellent appearance and eliminates inconveniences such as getting caught in the hand.

In addition, since the lower surface of the bottom of the ring body and the connecting part of the holding piece have a gently curved surface, it is unlikely that dirt will accumulate on the bottom surface of the bottom of the ring body, and even if it does, it will be removed by cleaning. It can be easily washed and the weir body can always be kept clean.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the structure of a weir body made of polyethylene terephthalate resin according to the present invention. FIG. 2 is a vertical cross-sectional view of the main part showing the structure of the main part of the biaxial stretch blow forming mold device for the weir body shown in FIG. , FIG. 3 is a longitudinal sectional view showing one mode of molding of the holding piece of the piece in molding the weir body shown in FIG. 1. 1; Weir body, 1'; Piece, 2; Main body, 3゜3; Bottom,
4; Holding piece, 5; Extension pin, 6; Split mold, 7; Bottom mold, 8; Fitting hole.

Claims (1)

[Scope of utility model registration request] A ring body 1 made of polyethylene terephthalate resin that has been biaxially stretched and blow-shaped, has a truncated frustum-shaped bottom part 3 that rises up in a gentle line, and has a height set at the center of the lower surface of the bottom part 3. A ring body made of polyethylene terephthalate resin, in which a holding piece 4 in the shape of a spherical arc smaller than a hemisphere is provided with a height that does not exceed the height, and the connecting portion between the holding piece 4 and the lower surface of the bottom part 3 is a curved surface.