JPH0312648Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a polyester resin bottle manufactured by biaxial stretch blow molding.

[Background Art and Issues to be Solved] Bottles for accommodating beer, wine, soft drinks, etc. can be easily manufactured by biaxial stretch blow molding of polyester resin.

This polyester resin bottle is of a self-supporting type with a hemispherical bottom raised in the direction of decreasing the bottle volume. This raised-bottom bottle has a problem in that the raised bottom part changes in a direction to expand the bottle volume due to the pressure, temperature, etc. of the contents during filling.
In particular, when a liquid having a temperature higher than the glass transition temperature is filled, the bottom part is softened by the heat of the filling material, resulting in significant deformation.

For this reason, a structure has been proposed in the past in which a plurality of ribs are made to protrude in the radial direction along the generatrix of the raised bottom part to strengthen the bottom part.
No. 57330).

However, the resin tends to be incompletely stretched in the raised bottom part of polyester resin bottles, resulting in uneven wall thickness of the raised bottom part, and this uneven part is noticeable from the outside, giving an unnatural feel.

The present invention takes the above facts into consideration, and aims to provide a polyester resin bottle that has a structure in which the raised bottom part is not easily deformed due to the pressure and temperature of the filling material, and can make uneven wall thickness less noticeable. It is.

[Summary and operation of the invention] In the polyester resin bottle according to the invention, a polyester resin mainly composed of polyethylene terephthalate is biaxially stretched and blow molded, and the bottom wall is indented in a dome shape toward the inside of the bottle. In a bottle with a raised bottom, a) the height of the top of the dome from the ground surface of the bottle is 20 to 50% of the diameter at the lower end of the periphery of the dome, and b) from the top of the dome or near the top of the dome to the dome surface. Along, 1/4~ across the generatrix of the dome surface
Spiral-like unevenness is formed on the inner and outer surfaces of 3 to 5 domes that rotate by 1/2, and c) The dome periphery with the spiral-like unevenness has an upright wall of 0 to 20 degrees at the angle formed with the vertical line. and (d) characterized by the formation of fat pockets along the spiral irregularities.

In this way, in the present invention, the reinforcing means has spiral irregularities extending from the top of the dome or the vicinity of the dome, which disperses the stress caused by the falling impact when filling the heated liquid and prevents the concentration of stress on specific parts of the reinforced part. However, by forming wall pockets along the spiral irregularities, resistance to the pressure caused by the filler is provided, and non-uniform wall thickness is made less noticeable when viewed from the outside. Preferably, the thickening formed in the spiral unevenness is thin in areas where the angle with the vertical line is small, and where the angle with the vertical line is large,
For example, by forming it thicker around 90 degrees, it is possible to create a structure that can withstand internal pressure better.

In the present invention, the vertical section of the raised bottom part is approximately V-shaped due to the periphery part which slopes from the lower end of the bottle circumferential wall to the ground contact part so that the diameter decreases at the ground contact part by 10 to 30% of the diameter of the bottom end of the peripheral wall, and the dome periphery part. By doing so, the strength of the raised bottom portion can be further increased.

In addition, the spiral unevenness forms a stepped wall with an approximately 1/4 arc in cross section taken along a vertical line that includes the center axis of the bottle around the dome, so this wall can withstand internal pressure and has great strength. be able to.

[Example] Fig. 3 shows a polyester resin bottle 10 to which the present invention is applied. In this bottle 10, the diameter of the top of a cylindrical peripheral wall portion 12 is reduced to form a neck portion 14, and a male thread 1 is carved on the outer periphery of this neck portion 14.
A cap (not shown) is screwed onto 6 to seal the inside.

As shown in FIGS. 1 and 4, the lower end of the peripheral wall 12 has an inclined part 20 that is inclined toward the grounding part 18 by 10 to 30% of the diameter of the lower end of the peripheral wall 12. are doing. The grounding portion 18 is connected to the outer peripheral portion of the bottom wall 22, and the bottom wall 22 has a raised portion 24 formed slightly higher in the center. The central portion of this raised portion 24 is a dome-shaped raised bottom portion 26 that is raised in the direction of decreasing the internal volume of the bottle.

This raised bottom portion 26 is a recess with a top portion 28 projecting slightly downward. Four spiral protrusions 30 extend from near the top 28 along the dome surface.
Four of them are formed so as to cross the generatrix of the dome surface (the radial line from the top 28 in FIG. 2) and rotate 1/4 to 1/2 of a turn (approximately 1/4 of a turn in this embodiment). The number of spiral protrusions 30 is preferably 3 to 5,
Further, the starting end may be provided from the top portion 28.

As a result, these four protrusions 30 protrude toward the outside of the bottle, the portion between these protrusions 30 protrudes toward the inside of the bottle, and these together form an uneven spiral on the inner and outer surfaces of the dome. It has an uneven shape.

As shown in FIGS. 1 and 4, this spiral convex strip 30 has a crescent-shaped cross-section, and has a thick wall 32 in the middle that is concave toward the inside of the bottle and convex toward the outside. ing. Therefore, this meat pocket 32 has sufficient resistance against the pressure of the filling material.

The peripheral edge of the raised bottom part 26 has an acute angle with the vertical line of the bottle 10, and has a stepped upright wall 34 that has a substantially 1/4 arc in cross section taken along a vertical plane that includes the central axis of the bottle 10. . This upright wall 34 preferably has an angle θ of 0 to 20 degrees with the vertical line of the bottle 10, and forms a substantially V-shape together with the inclined portion 20 at the lower end of the outer periphery of the bottle. This standing wall 34 part does not need to have a meat pocket,
Even if the wall is thin, the angle is close to the vertical line of the bottle 10, so it can sufficiently cope with the pressure of the filling. The upright wall 34A formed at the intermediate portion of the raised bottom portion 26 can also be made thin in the same manner.

The height of the top of the raised bottom part 26 from the ground surface of the bottle is
It is desirable that the diameter be 20 to 50% of the diameter at the lower end of the raised bottom portion 26, that is, the lower end of the standing wall 34.

The bottle 10 of this embodiment formed in this manner can be made into a polyester resin bottle as shown in FIG. 1 by blow molding a cylindrical preformed material with a predetermined wall thickness in a female mold. can. This female mold has a protrusion corresponding to the bottom surface of the bottle of the raised bottom part 26 shown in FIGS. Therefore, during blow molding, the polyester material is pressed against the female protrusion, forming a raised bottom portion 26 as shown in FIGS. 1 and 4.

During molding, in order to impart heat resistance, heating the mold during blow molding (90-130°C, 5-10 seconds) strengthens the mold and prevents the bottle from sagging downward due to thermal deformation. Obtainable.

When the filling is injected into the bottle 10, the raised bottom portion 26 receives a force that deforms in the direction of expanding the bottle volume due to the pressure of the filling. If the temperature of the filling is higher than about 70° C., the raised bottom portion 26 is likely to deform due to softening of the material.

However, in the raised bottom part 26 of this embodiment, the spiral protrusion 30 has a thickening 32 to improve the strength of the raised bottom part 26, and has a stress dispersion (concentration prevention effect) based on the spiral shape. Therefore, the amount of deformation is extremely small and it can have sufficient strength. In particular, the raised bottom part 26 is reinforced with a fat pad 32 in the part where the angle with the vertical line is large.
It can have sufficient internal pressure resistance.

Further, in this bottle 10, the flesh pocket 32 has a spiral protrusion 3.
Since it is provided along the
The flesh pockets 32 do not stand out unnaturally, and the flesh pockets 32 are scattered and have a blurred appearance, reducing the sense of discomfort.

Note that the flesh pocket 32 in the above embodiment is formed by the spiral protrusion 3
0 has a crescent-shaped cross section and is thick-walled, but the portion between the protrusions 30 indicated by reference numeral 32A in FIGS. 1 and 4 may be thickened and used as a thick wall. This fat pocket 32A continues to a thin stepped wall 34 when traced toward the bottom along the raised bottom portion 26.

Further, the cross-sectional shape of the raised bottom portion 26 is not limited to a spherical dome shape, but other shapes such as a trapezoid shape and a conical shape can also be applied.

[Effects of the invention] Since the polyester resin bottle according to the invention has the above structure, it has sufficient strength against the filler and can make uneven wall thickness at the raised bottom part less noticeable. Has excellent effects.

[Brief explanation of the drawing]

Fig. 1 is a sectional view taken along the line shown in Fig. 2, showing an embodiment of the polyester resin bottle according to the present invention, Fig. 2 is a sectional view taken along the line taken in Fig. 1, and Fig. 3 is a front view showing the bottle of this embodiment. , Fig. 4 is a sectional view taken along the line of Fig. 2, Fig. 5
The figure is a perspective view of the bottom-up part of the bottle seen from below. DESCRIPTION OF SYMBOLS 10... Bottle, 12... Peripheral wall part, 22... Bottom wall, 26...
Bottom raised part, 30... spiral convex stripe, 32, 32A... meat pocket, 34... standing wall.

Claims (1)

[Claims for Utility Model Registration] (1) A polyester resin mainly composed of polyethylene terephthalate is biaxially stretched and blow molded, and the bottom wall curves inward in a dome shape to form a raised bottom part. In the bottle, a) the height of the top of the dome from the ground plane of the bottle constitutes 20 to 50% of the diameter at the lower end of the periphery of the dome, b) from the top of the dome or near the top of the dome,
Along the dome surface, cross the generatrix of the dome surface 1/
Spiral-like unevenness is formed on the inner and outer surfaces of 3-5 domes that rotate by 4-1/2, and c. The spiral-like unevenness around the dome forms an upright wall with an angle of 0 to 20 degrees at the angle formed with the vertical line. d. A polyester resin bottle characterized by having: (d) a flesh pocket formed along the spiral irregularities. (2) The vertical cross-section of the raised bottom part is formed by the periphery of the dome and the periphery where the diameter decreases from the lower end of the bottle peripheral wall to the ground contact part by 10 to 30% of the diameter of the lower end of the peripheral wall. The polyester resin bottle according to claim (1) of the utility model registration claim, which is approximately V-shaped. (3) The spiral unevenness is approximately 1/2 in the cross section taken along the vertical plane including the central axis of the bottle in the periphery of the dome.
The polyester resin bottle according to claim (1) or (2) of the above-mentioned utility model registration claim, which forms a four-arc stepped wall.