JP5678555B2 - 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. 6). 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 provides a plastic bottle having a mouth, a neck, a body, and a bottom, hot-filling the liquid inside the bottle, adding a liquefied gas, The petaloid shape has a plurality of petaloid legs extending radially from the central part to the peripheral part, and a valley part, each petaloid leg has a grounding part, and the width corresponding to the grounding part of each valley part is t1 When the width of each petaloid leg corresponding to the ground contact part is t2, the length of each petaloid leg is t3, and the maximum diameter of the torso is t4, 0.90 <t1 / t2 < 1.40 and 0 .45 <t3 / t4 < 0.52 A plastic bottle characterized by having a structure.

  The present invention is a plastic bottle characterized in that the bottom portion has 5 to 9 petaloid legs.

  The present invention is the plastic bottle characterized in that the thickness of the petaloid leg at the contact portion is 0.03 mm to 0.40 mm.

  The present invention is the plastic bottle characterized in that the filling temperature of the content liquid is 60 ° C to 95 ° C.

  According to the present invention, the width corresponding to the ground contact portion of each valley is t1, the width corresponding to the ground contact portion of each petaloid leg is t2, the length of each petaloid leg is t3, When the diameter is t4, 0.60 <t1 / t2 <1.90 and 0.40 <t3 / t4 <0.65. As described above, the width of the valley is made larger than that of the conventional bottle, and the length of the petaloid leg is made longer than that of the conventional bottle. This enables hot filling of the contents liquid and addition of liquefied gas, so that when the inside of the bottle is made positive pressure, the pressure inside the bottle can be received by the trough, and deformation or inversion of the bottom (buckle) ) Can be prevented.

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. FIG. 6 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 5 are views showing 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.

  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 FIG. 4) 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. 4, when the width corresponding to the grounding portion 32a of each valley 33 is t1, and the width corresponding to the grounding portion 32a of each petaloid leg 32 is t2, 0.60 <t1 / t2 <1. .90. Furthermore, it is more preferable that 0.90 <t1 / t2 <1.40. In the present embodiment, “the width corresponding to the grounding portion 32a of the valley portion 33” means the width of the valley portion 33 between the grounding portions 32a of the petaloid legs 32 adjacent to each other, as shown in FIG. Say. Note that when t1 / t2 ≦ 0.60, the width of the valley portion 33 is narrowed, so that it is difficult to obtain the effect of preventing buckling of the bottom portion 30 when the inside of the bottle is set to a positive pressure. On the other hand, when t1 / t2 ≧ 1.90, the width of the petaloid leg 32 becomes narrow and the stability of the bottle is impaired. Moreover, since the unevenness | corrugation of the bottom part 30 becomes large because the width | variety of the petaloid leg 32 becomes narrow, there exists a possibility that whitening (thinning) by overstretching may generate | occur | produce in the grounding part 32a of the petaloid leg 32 at the time of blow molding.

  Furthermore, in FIG. 5, when the length of each petaloid leg 32 is t3, the ratio (t3 / t4) of the length t3 of the petaloid leg 32 to the maximum diameter t4 of the trunk 20 is 0.40 <t3 / t4 <0.65. Further, 0.45 <t3 / t4 <0.52 is more preferable. In the present embodiment, “the length of the petaloid leg 32” refers to a vertical distance from the ground contact portion 32a of the petaloid leg 32 to the upper end 32d of the petaloid leg 32 (or the upper end 33a of the valley 33). When t3 / t4 ≦ 0.40, the petaloid legs 32 and the valleys 33 are short in length, so that it is difficult to obtain the effect of preventing the buckling of the bottom 30 when the inside of the bottle is set to a positive pressure. On the other hand, when t3 / t4 ≧ 0.65, the length of the petaloid leg 32 becomes longer and the center of gravity becomes higher, so that the stability of the bottle is impaired. Moreover, since the unevenness | corrugation of the bottom part 30 becomes large because the length of the petaloid leg 32 becomes long, there exists a possibility that whitening (thinning) by over-drawing may generate | occur | produce in the grounding part 32a of the petaloid leg 32 at the time of blow molding.

  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. The main material of the preform, that is, the plastic bottle 10 is a thermoplastic resin, in particular, PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PLA (polylactic acid) as a main component. It is preferable to do.

  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, the ratio (t1 / t2) of the width t1 of the valley 33 to the width t2 of the petaloid leg 32 is set to 0.60 <t1 / t2 <1.90. That is, compared with the conventional petaloid bottle, the width of the valley portion 33 is increased and the width of the petaloid leg 32 is decreased. In the present embodiment, the ratio (t3 / t4) of the length t3 of the petaloid leg 32 to the maximum diameter t4 of the trunk portion 20 is set to 0.40 <t3 / t4 <0.65. That is, compared with the conventional petaloid bottle, the length of the trough 33 is made longer. Thereby, even if the inside of the closed plastic bottle 10 becomes a positive pressure and a force acts from the inside of the plastic bottle 10 to the outside, the trough 33 can receive this force. As a result, deformation (buckling) of the bottom portion 30 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 no pressure (0 kPa) or positive pressure is maintained. In this case, the deformation of the bottom 30 is relatively suppressed, and buckling does not occur at the bottom 30.

  Thus, according to the present embodiment, the ratio (t1 / t2) of the width t1 of the valley 33 to the width t2 of the petaloid leg 32 is 0.60 <t1 / t2 <1.90, and the petaloid leg 32 Since the ratio (t3 / t4) of the length t3 of the body 20 to the maximum diameter t4 of the body portion 20 was set to 0.40 <t3 / t4 <0.65, the shape of the bottom 30 compared to the conventional petaloid bottle The shape is more like a sphere. Thereby, when liquid nitrogen (LN2) is dropped after hot filling and the inside of the closed plastic bottle 10 becomes positive pressure, deformation of the bottom 30 can be reduced, and buckling of the bottom 30 is prevented. be able to.

  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 following five types of plastic bottles (Example 1, Comparative Examples 1 to 4) 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. The ratio (t1 / t2) of the width t1 of the valley 33 to the width t2 of the petaloid leg 32 was 1.00. The ratio (t3 / t4) of the length t3 of the petaloid leg 32 to the maximum diameter t4 of the body portion 20 was 0.50. This plastic bottle 10 (Example 1) is made thinner than a plastic bottle generally used conventionally.

(Comparative Example 1)
Except that the ratio (t1 / t2) of the width t1 of the trough 33 to the width t2 of the petaloid leg 32 was 0.60, the same weight and thickness as in Example 1 were obtained. A 500 ml plastic bottle (Comparative Example 1) was prepared.

(Comparative Example 2)
Except that the ratio (t1 / t2) of the width t1 of the trough 33 to the width t2 of the petaloid leg 32 was 1.90, the same weight and thickness as in Example 1 were obtained. A 500 ml plastic bottle (Comparative Example 2) was prepared.

(Comparative Example 3)
The same weight and meat as in Example 1 except that the ratio (t3 / t4) of the length t3 of the petaloid leg 32 to the maximum diameter t4 of the body part 20 was 0.40. A plastic bottle for 500 ml having a thickness (Comparative Example 3) was produced.

(Comparative Example 4)
The same weight and meat as in Example 1 except that the ratio (t3 / t4) of the length t3 of the petaloid leg 32 to the maximum diameter t4 of the body part 20 was 0.65. A plastic bottle for 500 ml having a thickness (Comparative Example 4) was produced.

  In Comparative Examples 2 and 4, a molding failure of the petaloid leg tip (whitening due to overstretching) occurred during blow molding, but other Examples 1 and Comparative Examples 1 and 3 had good blow moldability.

  Next, the content liquid was filled in three types of plastic bottles (Example 1, Comparative Examples 1 and 3) that had good blow moldability, 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, for each plastic bottle, (1) leg tip moldability, (2) depth at the center when cooled to room temperature (t5 '), (3) internal pressure after cooling, (4) grounding Stability was measured (see Table 1). (4) As a method for verifying the grounding stability, a plastic bottle at room temperature was placed upright on an inclined surface having a gradient of 15 °, and it was verified whether or not the plastic bottle would fall.

  As a result, the plastic bottle 10 of Example 1 was upright (t5 ′ ≧ 0 mm) in a state where the positive pressure was maintained after cooling (internal pressure after cooling> 0 kPa), and the grounding stability was also good.

  On the other hand, the plastic bottles of Comparative Examples 1 and 3 became negative pressure after cooling (internal pressure after cooling <0 kPa), and the bottom was inverted (t5 ′ <0 mm).

  As a result, it can be said that 0.60 <t1 / t2 <1.90 and 0.40 <t3 / t4 <0.65 are preferable.

DESCRIPTION OF SYMBOLS 10 Plastic bottle 11 Mouth part 12 Neck part 13 Shoulder part 15 Content liquid 16 Head space 17 Cap 20 Trunk part 30 Bottom part 31 Center part 32 Petaloid leg 33 Valley part

Claims (4)

In a plastic bottle with a mouth, a neck, a torso, and a bottom,
Hot-fill the bottle with the content liquid, add liquefied gas,
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 a valley part,
Each petaloid leg has a ground contact,
When the width corresponding to the grounding portion of each valley is t1, the width corresponding to the grounding portion of each petaloid leg is t2, the length of each petaloid leg is t3, and the maximum diameter of the trunk is t4 0.90 <t1 / t2 < 1.40 and 0.45 <t3 / t4 < 0.52 .   The plastic bottle according to claim 1, wherein the bottom portion has 5 to 9 petaloid legs.   3. The plastic bottle according to claim 1, wherein a thickness of the petaloid leg at the contact portion is 0.03 mm to 0.40 mm.   The plastic bottle according to any one of claims 1 to 3, wherein a filling temperature of the content liquid is 60 ° C to 95 ° C.

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