JP5652702B2 - Plastic bottle - Google Patents

Description

  The present invention relates to a plastic bottle including a mouth, a neck, a body, and a bottom.

  Conventionally, as plastic bottle filling methods, there are an aseptic filling method (room temperature filling method) and a hot filling method (high temperature filling method). Of these, the hot filling method has been used for a long time as a filling method for canned beverages.

  Generally, a container for hot filling needs to have heat resistance. In hot filling, since the filling temperature of the content liquid is high, when the bottle is cooled to room temperature after filling, the volume of the content liquid and the head space decreases, and the pressure inside the bottle decreases. As a result, the hot-filled product is more deformed by the reduced pressure of the bottle than the aseptic-filled product (see FIG. 7). For this reason, especially when plastic bottles are used as containers for hot filling, the bottles must be adjusted to a thickness that can withstand the heat and vacuum absorption caused by hot filling, resulting in a lighter bottle. There is a problem that it is difficult.

  On the other hand, in order to suppress the amount of pressure reduction after hot filling, a technique of dropping liquid nitrogen (LN2) after hot filling has been developed (Patent Document 1).

JP 2005-350090 A

  In recent years, it has been desired to reduce the amount of plastic material used for bottles and to further reduce the weight of plastic bottles. However, when the above-described technique of dropping liquid nitrogen (LN2) is used for a plastic bottle that has been reduced in weight, the bottom of the bottle may be inverted due to heat from hot filling and an increase in internal pressure immediately after filling (back). Called ring).

  The present invention has been made in consideration of such points, and it is possible to prevent inversion (buckling) of the bottom even when the content liquid is hot-filled and the inside is positive pressure. The purpose is to provide plastic bottles.

The present invention comprises a plastic bottle comprising a mouth, a neck, a body, and a bottom, and a cap is attached to the mouth . The bottom is a central part located in the center, and from the central part to the peripheral part. It has a petaloid shape having a plurality of petaloid legs extending radially and valleys formed between adjacent petaloid legs, and the central part has an annular surface and a recess recessed inwardly from the annular surface, The bottle is hot filled with the liquid content at a filling temperature of 60 ° C. to 95 ° C. , liquefied gas is added , the distance between the bottom of the recess and the ground contact portion of the petaloid leg is t1, and the distance between the bottom of the recess and the annular surface is When t2, the diameter of the concave portion is t3, and the maximum diameter of the trunk portion is t4, 0.20 <t2 / t1 <0.60 and 0.10 <t3 / t4 <0.40, and in the ground contact portion of the petaloid leg Thickness is 0.03mm to 0.40m , And the when viewed from the bottom, a plastic bottle, wherein the wider towards the valley than the petaloid feet.

  The present invention is a plastic bottle having 5 to 9 petaloid legs at the bottom.

  The present invention is a plastic bottle characterized in that the recess has a circular shape when viewed from the bottom.

  The present invention is the plastic bottle characterized in that the recess has a dome shape when viewed from the vertical end face.

  According to the present invention, the bottom portion has a petaloid shape having a central portion located in the center and a plurality of petaloid legs extending radially from the central portion to the peripheral portion, and the central portion is formed from the annular surface and the annular surface. And a recess that is recessed. This makes it possible to reduce deformation of the bottom and prevent inversion (buckling) of the bottom even when the bottle is filled with hot liquid and liquefied gas is added to create a positive pressure inside the bottle. can do.

FIG. 1 is a front view showing a plastic bottle in a filled state according to an embodiment of the present invention. FIG. 2 is a vertical end view (a cross-sectional view taken along line AA in FIG. 1) showing the plastic bottle in an empty state according to an embodiment of the present invention. FIG. 3 is a top view showing a plastic bottle in an empty state according to an embodiment of the present invention. FIG. 4 is a bottom view showing the plastic bottle in an empty state according to an embodiment of the present invention. FIG. 5 is an enlarged end view showing the bottom of the plastic bottle in an empty state according to an embodiment of the present invention. FIGS. 6A to 6C are enlarged end views showing the bottom of the plastic bottle in a filled state according to the embodiment of the present invention. FIG. 7 is a diagram comparing the amount of reduced pressure between an aseptic filling product and a hot filling product.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 show an embodiment of the present invention.

  First, the outline of the plastic bottle according to the present embodiment will be described with reference to FIGS. In the present specification, “upper” and “lower” refer to the upper and lower sides of the plastic bottle 10 in an upright state (FIGS. 1 and 2), respectively.

  As shown in FIGS. 1 to 4, the plastic bottle 10 includes a mouth part 11, a neck part 12 connected to the mouth part 11, a shoulder part 13 connected to the neck part 12, and a body part 20 connected to the shoulder part 13. And a bottom portion 30 connected to the body portion 20.

  Among these, the trunk | drum 20 consists of a substantially cylindrical shape, The surface is comprised substantially flat. As shown in FIG. 1, the content liquid 15 is hot-filled inside the plastic bottle 10, and liquefied gas is added into the head space 16 on the content liquid 15. Further, a cap 17 is attached to the mouth portion 11.

  As shown in FIGS. 2 and 4, the bottom 30 has a petaloid shape. That is, the bottom part 30 has a central part 31 located at the center and a plurality (in this case, five) petaloid legs 32 extending radially from the central part 31 toward the peripheral edge part 30 b of the bottom part 30.

  As shown in FIG. 4, the five petaloid legs 32 are arranged at equal intervals in the circumferential direction along the peripheral edge portion 30 b of the bottom portion 30. Five or more petaloid legs 32 are preferably provided to stably erect the plastic bottle 10, but the upper limit is preferably about nine from the viewpoint of moldability. In order to effectively prevent buckling, the number of petaloid legs 32 is preferably an odd number, and more preferably five.

  As shown in FIGS. 2 and 4, each petaloid leg 32 includes a grounding portion 32 a that extends circumferentially, an inner inclined surface 32 b that extends upward from the grounding portion 32 a toward the central portion 31, and a grounding portion. An outer inclined surface 32c extending upward from 32a toward the peripheral edge 30b.

  On the other hand, valleys 33 are formed between adjacent petaloid legs 32. Each trough 33 is formed of a curved surface extending upward from the central portion 31 toward the peripheral edge 30b. Each trough 33 constitutes a part of a spherical surface that curves downward in a cross section from the central portion 31 toward the peripheral edge 30b (see FIG. 2). In this case, each valley part 33 may consist of a part of dome-shaped curved surface.

  In the present embodiment, the central portion 31 has a circular annular surface 34 and a concave portion 35 that retracts inward (upward) from the annular surface 34. The shape of the recess 35 is preferably circular when viewed from the bottom, from the viewpoint of increasing the pressure resistance of the bottom 30. Furthermore, from the viewpoint of improving the moldability, it is preferable that the vertical end surface shape (FIG. 2) of the recess 35 is a dome shape. In addition, the shape of the recess 35 may be a cylindrical shape, or may be a shape in which a hemisphere is connected to the cylinder.

  The size of the plastic bottle 10 is not limited, and may be any size bottle. For example, when the capacity of the plastic bottle 10 is 500 ml, the diameter t4 (see FIGS. 4 and 5) of the body 20 can be set to 60 mm to 70 mm. Further, when the capacity of the plastic bottle 10 is 1000 ml, the diameter t4 of the body 20 can be set to 70 mm to 90 mm, and when 1500 ml, the diameter t4 of the body 20 can be set to 80 mm to 100 mm.

  In FIG. 5, when the distance between the bottom 35a of the recess 35 and the ground contact portion 32a of the petaloid leg 32 is t1, and the distance between the bottom 35a of the recess 35 and the annular surface 34 is t2, 0.20 <t2 / t1 < It is preferable to be 0.60. In addition, when t2 / t1 ≧ 0.60, the unevenness of the bottom 30 becomes large, and thus there is a possibility that whitening (thinning) due to overstretching may occur in the ground contact portion 32a of the petaloid leg 32 during blow molding. On the other hand, when t2 / t1 ≦ 0.20, since the depth of the recess 35 is shallow, it is difficult to obtain the effect of preventing the buckling of the bottom 30.

  In FIG. 5, when the diameter of the recess 35 is t3 and the maximum diameter of the body 20 is t4, it is preferable that 0.10 <t3 / t4 <0.40 (see FIG. 6A). When t3 / t4 ≧ 0.40, the radius of curvature R1 of the recess 35 is increased, so that it is difficult to obtain the effect of preventing the buckling of the bottom 30 (see FIG. 6B). Furthermore, since the inner inclined surface 32b of the petaloid leg 32 becomes steep, the petaloid leg 32 may be whitened (thinned) due to overstretching due to poor molding. On the other hand, when t3 / t4 ≦ 0.10, the effect of preventing buckling of the bottom portion 30 is difficult to obtain because the diameter t3 of the recess is short (see FIG. 6C). For this reason, it is preferable that 0.20 <t2 / t1 <0.60 and 0.10 <t3 / t4 <0.40.

  The wall thickness of the ground contact portion 32a of the petaloid leg 32 of the plastic bottle 10 can be 0.03 mm to 0.40 mm. Thus, by reducing the thickness of the plastic bottle 10, the weight of the plastic bottle 10 can be reduced.

  The plastic bottle 10 can be manufactured by biaxially stretch blow molding a preform manufactured by injection molding a synthetic resin material. In addition, it is preferable to use a thermoplastic resin, especially PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), PEN (polyethylene naphthalate) as a material of the preform, that is, the plastic bottle 10.

  Next, the operation of the present embodiment having such a configuration will be described.

  First, the content liquid 15 such as green tea or coffee is filled in an empty plastic bottle 10 whose interior has been cleaned, for example, at a temperature of 60 to 95 ° C. (hot filling).

  Subsequently, a liquefied inert gas (liquefied gas) such as liquid nitrogen is filled into the head space 16 on the content liquid 15, and the cap 17 is closed. Next, the plastic bottle 10 is tilted horizontally, for example, to bring the high-temperature content liquid 15 into contact with the back surface of the cap 17, thereby sterilizing the back surface of the cap 17 and the inside of the plastic bottle 10 (overturn sterilization). The method of sterilization may be a hot water shower called a paste riser depending on the type of the inner solution 15. Immediately after the closure, the inside of the plastic bottle 10 becomes a positive pressure by the filled inert gas or content liquid 15.

  In this way, when the inside of the plastic bottle 10 becomes a positive pressure, a force acts from the inside (upper side) to the outside (lower side) of the plastic bottle 10, and at the bottom portion 30, generally from the inside toward the outside. Pressure is applied. In this case, the central portion 31 of the bottom portion 30 acts so as to bulge outward.

  In the present embodiment, a concave portion 35 that is recessed inward from the annular surface 34 is provided in the central portion 31 of the bottom portion 30. As a result, the inside of the closed plastic bottle 10 becomes a positive pressure, and even when a force acts from the inside of the plastic bottle 10 to the outside, the deformation of the bottom 30 can be suppressed, and the back of the bottom 30 can be suppressed. Rings can be prevented.

  Thereafter, the temperature of the plastic bottle 10 decreases to room temperature. At this time, the volume of the content liquid 15 and the head space 16 is reduced, so that the pressure inside the plastic bottle 10 is reduced, but still maintains no pressure (0 kPa) or positive pressure. In this case, the deformation of the bottom 30 is relatively suppressed, and buckling does not occur at the bottom 30.

  As described above, according to the present embodiment, since the concave portion 35 that is retracted inward from the annular surface 34 is provided in the central portion 31 of the bottom portion 30, the liquid nitrogen (LN2) is dropped after the hot filling to close the plug. When the inside of the plastic bottle 10 becomes a positive pressure, deformation of the bottom 30 can be reduced, and buckling of the bottom 30 can be prevented.

  Further, according to the present embodiment, buckling of the bottom portion 30 can be prevented, so that the plastic bottle 10 can be formed thin, the plastic bottle 10 can be reduced in weight, and the plastic material can be used. The amount can be reduced.

  Next, specific examples in the present embodiment will be described.

(Evaluation of blow moldability and heat and pressure resistance)
The five types of plastic bottles (Example 1 and Comparative Examples 1 to 4) listed below were evaluated for blow moldability and heat and pressure resistance, respectively.

Example 1
A plastic bottle 10 (Example 1) for 500 ml having the configuration shown in FIGS. 1 to 5 was produced. In this case, the plastic bottle 10 (Example 1) was produced by carrying out biaxial stretch blow molding of 18g preform. In Example 1, the ratio (t2 / t1) of the distance t2 between the bottom 35a of the recess 35 and the annular surface 34 to the distance t1 between the bottom 35a of the recess 35 and the ground contact portion 32a of the petaloid leg 32 is 0.50. there were. The ratio (t3 / t4) of the diameter t3 of the concave portion 35 to the maximum diameter t4 of the body portion 20 was 0.30. This plastic bottle 10 (Example 1) is made thinner than a plastic bottle generally used conventionally.

(Comparative Example 1)
A 500 ml plastic bottle 10 having the same weight and thickness as in Example 1 (comparison) except that the ratio (t2 / t1) of the distance t2 to the distance t1 was set to 0.20. Example 1) was prepared.

(Comparative Example 2)
A 500 ml plastic bottle 10 having the same weight and thickness as Example 1 (comparison) except that the ratio (t2 / t1) of the distance t2 to the distance t1 was 0.60. Example 2) was prepared.

(Comparative Example 3)
A 500 ml plastic bottle 10 having the same weight and thickness as in Example 1 (Comparison) except that the ratio (t3 / t4) of the distance t3 to the distance t4 was set to 0.10. Example 3) was prepared.

(Comparative Example 4)
A 500 ml plastic bottle 10 having the same weight and thickness as in Example 1 (Comparison), except that the ratio (t3 / t4) of the distance t3 to the distance t4 was set to 0.40. Example 4) was prepared.

  Next, the content liquid was filled in these five types of plastic bottles (Example 1 and Comparative Examples 1 to 4), and the bottles were closed. At this time, first, the content liquid was filled into each plastic bottle at a temperature of 90 ° C. (hot filling), and then liquid nitrogen (LN 2) was dropped into each plastic bottle. Thereafter, a cap was attached to the mouth of each plastic bottle to obtain a closed plastic bottle.

  Next, with respect to each plastic bottle, (1) the depth (distance t1 ′) of the central portion when the temperature reached room temperature after cooling, and (2) the internal pressure at this time were measured (see Table 1).

  As a result, the plastic bottle 10 of Example 1 was upright (t1 ′> 0 mm) in a state where the positive pressure was maintained even after cooling (internal pressure after cooling> 0 kPa), and the blow moldability was good. On the other hand, in the plastic bottles 10 of Comparative Examples 1 to 4, the internal pressure became negative after cooling (the internal pressure after cooling <0 kPa), and it was easy to fall over (t1 ′ <0 mm). Furthermore, whitening (thinning) occurred in the petaloid legs 32 of the plastic bottles 10 of Comparative Examples 2 and 4 due to overstretching due to molding failure.

  As a result, it can be said that 0.20 <t2 / t1 <0.60 and 0.10 <t3 / t4 <0.40 are preferable.

DESCRIPTION OF SYMBOLS 10 Plastic bottle 11 Mouth part 12 Neck part 13 Shoulder part 15 Contents liquid 16 Head space 17 Cap 20 Body part 30 Bottom part 31 Center part 32 Petaloid leg 33 Valley part 34 Annular surface 35 Recessed part

Claims (4)

In a plastic bottle with a mouth , a neck, a body, and a bottom, with a cap attached to the mouth ,
The bottom part has a petaloid shape having a central part located in the center, a plurality of petaloid legs extending radially from the central part to the peripheral part, and valleys formed between adjacent petaloid legs ,
The central portion has an annular surface and a recess recessed inward from the annular surface,
The content liquid is hot filled in the bottle at a filling temperature of 60 ° C. to 95 ° C. , liquefied gas is added ,
When the distance between the bottom of the recess and the ground contact portion of the petaloid leg is t1, the distance between the bottom of the recess and the annular surface is t2, the diameter of the recess is t3, and the maximum diameter of the body is t4, 0.20 <t2 / t1 <0.60 and 0.10 <t3 / t4 <0.40,
The thickness at the ground contact portion of the petaloid leg is 0.03 mm to 0.40 mm,
A plastic bottle characterized in that each valley is wider than each petaloid leg when viewed from the bottom side .   The plastic bottle according to claim 1, wherein the bottom portion has 5 to 9 petaloid legs.   The plastic bottle according to claim 1 or 2, wherein the recess has a circular shape when viewed from the bottom.   The plastic bottle according to any one of claims 1 to 3, wherein the concave portion has a dome shape when viewed from a vertical end surface.

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