JP2516648B2 - Bottle primary molded product - Google Patents

Description

The present invention relates to a structure of a biaxially stretch blow-molded relatively large-sized primary molded article for bottle molding, which is made of a synthetic resin, particularly a polyethylene terephthalate resin material. More specifically, it is an object of the present invention to provide a primary molded product capable of molding a bottle having a thick body portion.

[Conventional technology]

Currently, many synthetic resin bottle containers are used,
Especially as a large bottle container, polyethylene terephthalate resin, which is a crystalline synthetic resin material (hereinafter PET for simplicity)
A large bottle made of biaxially stretch blow-molded material has many excellent advantages in terms of content resistance, mechanical strength, price, disposal, etc., so it should be used in large quantities. Has become.

This PET biaxially stretched blow molded bottle body is formed by injection-molding a primary molded product in the shape of a bottomed straight tube, and the body of this primary molded product is heated to a temperature at which it can be stretched. Axial stretch blow molding is performed to form a bottle as a final molded product.

Thus, this type of biaxially stretched blow-molded bottle body is formed into a bottle by biaxially stretch-blow-molding the body of a linear molded bottomed primary molded article. For the body of the primary molded article to be molded, there is an upper limit to the draw ratio, there is an upper limit to the wall thickness due to the relationship between the temperature characteristics of the PET material and the temperature control required for blow molding operation,
Due to the mold release conditions of the primary molded product, which is an injection molded product, there is a limitation that even a part of the inner surface must not be located outside the extended surface of the inner peripheral surface of the mouth. There is a limitation, and for a bottle as a product, there is a limitation that the size of the mouth is limited to a value specified in advance.

That is, regarding the above, the limit is about 7 times in terms of area magnification, and regarding the above, in order to uniformly give rapid cooling and rapid heating to the primary molded product without causing whitening, its thickness is 4 mm is the upper limit, and the inner diameter of the body of the primary molded product must not be larger than the mouth, and further, the size of the mouth of the primary molded product that is the final molded part is limited. Therefore, the upper limit of the diameter of the body of the primary molded product is limited due to the above relationship.

[Problems to be solved by the invention]

As a result of the above-mentioned dimensional restrictions on the primary molded product, the inner diameter and wall thickness of the body of the primary molded product are significantly limited. Therefore, when it is desired to obtain a bottle with a larger storage volume. , It was necessary to increase the length of the body of the primary molded product to make it a bottle with a large body height. That is, since the upper limit of the inner diameter and wall thickness of the body of the primary molded product is limited, it is not possible to increase the thickness of the body of the bottle molded from this primary molded product. When it was desired to obtain a bottle of volume, there was no other way than increasing the height of the body of the bottle.

For this reason, the large bottle that has been biaxially stretch-blow-molded has a large height relative to its storage volume, and it is not possible to provide a sufficiently stable self-supporting posture holding ability. It is difficult to say that it has a good balance with the external appearance, and it is hard to say that it has a good appearance. Furthermore, the mechanical durability of the central part of the trunk is insufficient for the pressing force applied from the outside, and it tends to be Inconvenient buckling deformation occurs.

Therefore, the present invention provides a primary molded product capable of molding a much larger bottle than a conventional bottle under the conditions satisfying all the restrictions on the above-described primary molded product and a bottle as a product. That is the technical issue.

[Means for solving problems]

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

According to the means of the present invention, a plurality of pleats along the axial direction are formed by recessing and bending a portion of the cylindrical wall 6 of the bottomed straight cylindrical body 5 that is continuously provided at the lower end of the mouth cylinder 2 at each equal center angle into a vertical groove shape. It is to form the wall 7.

That is, the cylindrical wall 6 has a portion where the inner peripheral surface is located on a virtual cylindrical surface that is an extension of the inner peripheral surface of the mouth tube 2 and a fold that positions the inner peripheral surface within the virtual cylindrical surface. The wall portion 7 and the wall portion 7 are alternately arranged along the circumferential direction and have a flat cross-sectional shape with a uniform thickness, and the vertical strip portion formed by the fold wall portion 7 on the inner peripheral surface of the tubular body 5 has a front height. It is formed over a range.

[Action]

In this way, since each part of the cylindrical wall 6 at an equal center angle is depressed and curved in the fold wall portion 7, the circumferential length of the cylindrical wall 6 is a simple circular shape in which the flat cross-sectional shape of the cylindrical wall 6 is conventional. In comparison with the above case, the number is increased by a value determined according to the number of pleated wall portions 7 to be formed and the amount of depression of the pleated wall portions 7.

Therefore, the circumferential length of the tubular body 5 of the primary molded product 1 is larger than that of the conventional case even though the overall thickness of the tubular body 5 is the same as that of the conventional case. However, the thickness of the body portion 6'when the bottle 1'is biaxially stretch blow molded becomes large.

The biaxially stretch blow molding operation for the bottle 1'for the primary molded article 1 according to the present invention may be exactly the same as the conventional molding operation. That is, it is only necessary to uniformly heat the entire primary molded product 1 to a temperature at which the stretching effect can be obtained, and then pressurize the pressurized fluid into the primary molded product 1.

However, the stretched deformation mode of the cylindrical body 5 due to the press-fitting of the pressure fluid is significantly different from the conventional case. That is, when this pressure fluid is pressed into the tubular body 5, the fold wall portion 7 expands and deforms the recessed and curved wall structure before stretching and deformation of the tubular wall 6, so that the entire tubular wall 6 is not deformed. The plane cross-section of is a simple circle.

As described above, after the flat wall cross-sectional shape of the cylindrical wall 6 becomes a simple circle due to the expansion deformation of the fold wall portion 7, the cylindrical wall 6 is stretched and deformed as in the conventional case.

〔Example〕

In the case of the illustrated embodiment, the mouth tube 2 of the primary molded product 1 has a thread 3 provided around the outer peripheral surface thereof, and a flange 4 is provided below the thread 3 as in the case of the conventional primary molded product. I have set up. A bottom wall 8 of the tubular body 5 having a linear tubular shape with a bottom projects outward in a hemispherical shell shape. This cylinder 5 has a wall thickness of PE
The maximum wall thickness value allowed for biaxially stretch blow molding of T is set to 4 mm, and for the mouthpiece 2 which is generally only about 2 mm thick, the wall thickness difference to the outside is 2 mm. It is in a prime state.

The number of the pleated wall portions 7 formed on the tubular wall 6 is not specified, but the wall thickness value of the tubular wall 6, the inner diameter value of the tubular wall 6,
Further, it is set to an appropriate value according to the amount of depression of the fold wall portion 7. However, if the number of the corrugated wall portions 7 is small, the increase in the circumferential length of the cylindrical wall 6 that is substantially obtained is small,
On the contrary, if the number of the pleated wall portions 7 is too large, it becomes difficult to form the primary molded product 1 itself. Therefore, the number of the pleated wall portions 7 is actually 4 to 3 shown in FIG. The six shown in are suitable.

In the case of the embodiment of FIG. 2 in which the number of pleated wall portions 7 is 4, the substantial increase in the circumferential length of the cylindrical wall 6 obtained by molding the pleated wall portions 7 is about 16%, As shown in FIG. 4, four pleated wall portions 7 shown in FIG. 2 are provided as compared with a bottle body 1 ″ formed from a primary molded product having a conventional structure in which the pleated wall portion 7 is not provided. The bottle body 1'molded from the primary molded product 1 according to the present invention can increase the thickness of the body portion 6'by about 20%.

In the primary molded product 1 according to the present invention, since the pleated wall portion 7 is depressed in the cylindrical wall 6, the peripheral surface of the cylindrical wall 6 is the cylindrical body 5.
Since it is not located at a uniform distance with respect to the central axis of the, the heating operation for the primary molded product 1 for carrying out stretch blow molding, if a far-infrared heater or the like is used as in the conventional case, the distance is not uniform. Due to the uniformity, uniform heating of the entire tubular body 5 cannot be achieved. Therefore, when heating the primary molded product 1 according to the present invention, it is preferable to heat the entire primary molded product 1 in the atmosphere.

〔The invention's effect〕

As is clear from the above description, the present invention can increase the substantial circumferential length of the cylinder wall of the primary molded product of the biaxially stretched blow molded bottle body within the same dimension, and therefore, the present invention has a higher peripheral length. For the sake of size, a large bottle with a thick body and good appearance can be obtained, and as the body becomes thicker, the buckling strength against pressing force is higher, and Since the structure is simple by simply forming a plurality of pleated wall parts on the cylindrical wall by concave curve molding, it can be easily molded by changing the setting of the injection molding die, and biaxial stretching as usual. Since it can be molded into a bottle by a blow molding operation, it exhibits many excellent effects such as simple implementation.

[Brief description of drawings]

FIG. 1 is an overall vertical cross-sectional view showing an embodiment of the primary molded product according to the present invention, in which the vertical cross-sectional shape of the fold wall portion is indicated by a two-dot chain line. 2 and 3 are plan cross-sectional views of the cylindrical portion of the embodiment shown in FIG. 1, FIG. 2 shows a case where four fold wall portions are provided, and FIG. The case where six fold wall portions are provided is shown. FIG. 4 is an overall front view for comparing the thickness of the body of the bottle molded by the primary molded product according to the present invention with the bottle molded by the conventional primary molded product. The body is indicated by a chain double-dashed line. DESCRIPTION OF SYMBOLS 1; Primary molded product, 1 ', 1 "; Bottle, 2: Mouth tube, 3; Thread, 4;
Flange, 5; tubular body, 6; tubular wall, 6 '; trunk, 7; fold wall portion,
8; bottom wall.

Claims (1)

(57) [Claims] 1. A primary molded product (1) of a biaxially stretch blow molded bottle body (1 '), which is a cylinder wall of a bottomed straight cylinder body (5) connected to a lower end of a mouth cylinder (2). A primary molded product of a bottle body, which is formed by forming a vertical groove-like recessed curve at each part of (4) to form a plurality of fold wall portions (7) along the axial direction.