JP2012162287A - Plastic bottle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plastic bottle that can prevent reverse (buckling) of a bottom part even if the bottle is aseptically filled with a content fluid and the inside is turned into a positive pressure.SOLUTION: A plastic bottle 10 includes an opening part 11, a neck part 12, a barrel part 20 and a bottom part 30. Content fluid 15 is aseptically filled into the bottle 10, and liquefied gas is added thereon. The bottom part 30 has a center part 31 located on a center of the bottom part, a plurality of petaloid bases 32 radially extending from the center part 31 to a circumferential part 30b, and valley parts 33. When a width of each of the valley parts 33 corresponding to a ground part 32a is t1, a width of each of the petaloid bases 32 corresponding to the ground part 32a is t2, a length of each of the petaloid bases 32 is t3, and a maximum diameter of the barrel part 20 is t4, 0.30<t1/t2<1.60 and 0.05<t3/t4<0.35 are satisfied.

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 aseptic filling method) and a hot filling method (high temperature filling method).

  Of these, the aseptic filling method is a technique in which a plastic bottle is sterilized with a drug in an aseptic environment, and then a soft drink is filled into the sterilized plastic bottle at room temperature. When such an aseptic filling method is used, the plastic bottle is not exposed to a high temperature in the manufacturing process, and therefore it is generally possible to use a plastic bottle having low heat resistance.

JP 2009-298483 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 a soft drink is filled in a lighter plastic bottle at room temperature and liquid nitrogen (LN2) is dropped, the bottom of the bottle may be inverted due to an increase in internal pressure immediately after filling (referred to as buckling). .

  The present invention has been made in consideration of such points, and it is possible to prevent reversal (buckling) of the bottom even when the content liquid is filled aseptically and the bottle internal pressure increases immediately after filling. The aim is to provide a possible plastic bottle.

  The present invention relates to a plastic bottle having a mouth portion, a neck portion, a body portion, and a bottom portion, aseptic filling the content liquid inside the bottle, adding a liquefied gas, and the bottom portion is a central portion located at the center. 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 corresponding to the ground contact portion of each petaloid leg is t2, the length of each petaloid leg is t3, and the maximum diameter of the torso is t4, 0.30 <t1 / t2 <1.60 and 0 0.05 <t3 / t4 <0.35 is 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 ground contact portion is 0.03 mm to 0.25 mm.

  The present invention is a plastic bottle characterized in that the filling temperature of the content liquid is 10 ° C. to 40 ° 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, 0.30 <t1 / t2 <1.60 and 0.05 <t3 / t4 <0.35. 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. Thus, even when the inside of the bottle is set to a positive pressure, the pressure inside the bottle can be received by the trough, and deformation and inversion (buckling) of the bottom can be prevented.

  Moreover, when the weight reduction of the bottle is promoted, since the petaloid bottom is more uneven than the round bottom, the leg tip is thinned and the leg tip of the petaloid leg is liable to be crushed when a load is applied. In this case, the bottle cannot be kept in a horizontal state, causing load collapse. According to the present invention, both the blow moldability and the pressure resistance can be satisfied by defining the width of the valley and the length of the petaloid leg within the above-described ranges.

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 bottom view showing a plastic bottle in an empty state according to a comparative example.

  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 aseptically filled (normal temperature aseptic filling) in 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, 0.30 <t1 / t2 <1. .60. Further, when the thickness of the petaloid leg 32 at the ground contact portion 32a is 0.03 mm to 0.15 mm, 0.40 <t1 / t2 <1.40 is further satisfied from the viewpoint of bottle stability and pressure resistance. preferable. 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 ≦ 0.30, 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 ≧ 1.60, 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 0.05 <t3 / t4 <0.35. Further, when the thickness of the ground contact portion 32a of the petaloid leg 32 is 0.03 mm to 0.15 mm, it is more preferable that 0.10 <t3 / t4 <0.32 from the viewpoint of bottle stability and pressure resistance. . 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 ≦ 0.05, the petaloid leg 32 and the trough 33 are short, so that it is difficult to obtain the effect of preventing the buckling of the bottom 30 when the inside of the bottle is positive. On the other hand, when t3 / t4 ≧ 0.35, 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 0.25 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. As the main material of the preform, that is, the plastic bottle 10, a thermoplastic resin, particularly PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PLA (polylactic acid), etc., should be used. Is preferred.

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

  First, a medicine (sterilizing liquid) is put into the empty plastic bottle 10, and then the medicine is washed with a cleaning liquid and further dried with a dry gas to keep the inside of the plastic bottle 10 aseptic. It is preferable to use hydrogen peroxide or peracetic acid as a chemical, water as a cleaning liquid, and air as a dry gas. Moreover, as a method of making the inside of the plastic bottle 10 aseptic, not only a method using a drug but also a method using electron beam (EB) irradiation may be used. Next, the plastic bottle 10 is filled with the content liquid 15 sterilized in an aseptic filling machine (not shown) at a temperature of 10 ° C. to 40 ° C., for example. Examples of the content liquid 15 include tea beverages such as mineral water, green tea, and mixed tea, and beverages containing milk such as coffee.

  Subsequently, liquefied inert gas (liquefied gas) such as liquid nitrogen is sterilized, and the sterilized liquefied inert gas (liquefied gas) is filled in the head space 16 on the content liquid 15 and closed with a cap 17. To do. As a method for sterilizing the liquefied inert gas (liquefied gas), a method of passing through a fine filter is preferable. As the material of the filter, it is preferable to use a resin or a metal, and it is particularly preferable to use a polyolefin or a polyimide as the resin, and it is preferable to use a stainless steel as the metal. Moreover, it is preferable to employ a filter having a fineness of 0.01 μm to 1 μm. During this time, each step is performed under a sterile atmosphere. 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 0.30 <t1 / t2 <1.60. 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. Further, 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 0.05 <t3 / t4 <0.35. 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.

  Thus, according to the present embodiment, the ratio (t1 / t2) of the width t1 of the trough 33 to the width t2 of the petaloid leg 32 is 0.30 <t1 / t2 <1.60, and the petaloid leg 32 Since the ratio (t3 / t4) of the length t3 of the body portion 20 to the maximum diameter t4 of the body portion 20 is set to 0.05 <t3 / t4 <0.35, the shape of the bottom 30 compared to the conventional petaloid bottle The shape is more like a sphere. By this, by dropping liquid nitrogen (LN2) after aseptic filling, the deformation of the bottom 30 can be reduced when the inside of the closed plastic bottle 10 becomes positive pressure, and the buckling of the bottom 30 can be reduced. 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 pressure resistance)
The following 6 types of plastic bottles (Example 1 and Comparative Examples 1 to 5) were evaluated for blow moldability 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 0.60. The ratio (t3 / t4) of the length t3 of the petaloid leg 32 to the maximum diameter t4 of the body portion 20 was 0.20. 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 set to 0.30, 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 1.60, 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 set to 0.05. 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 0.35. A plastic bottle for 500 ml having a thickness (Comparative Example 4) was produced.

(Comparative Example 5)
A plastic bottle 50 (Comparative Example 5) for 500 ml having the configuration shown in FIG. 6 was produced. In this case, a plastic bottle 50 (Comparative Example 5) was produced by biaxially stretching blow molding a 28 g preform. In this plastic bottle 50 (Comparative Example 5), the ratio (t1 / t2) of the width t1 of the valley 33 to the width t2 of the petaloid leg 32 was 0.20. Further, the ratio (t3 / t4) of the length t3 of the petaloid leg 32 to the maximum diameter t4 of the body portion 20 was 0.40. This plastic bottle 50 (Comparative Example 5) has a thickness equivalent to that of a conventionally used plastic bottle.

  Among these six types of plastic bottles (Example 1 and Comparative Examples 1 to 5), the plastic bottles according to Comparative Examples 2 and 4 had molding defects (whitening due to overstretching) of the petaloid leg tips during blow molding. Other plastic bottles according to Example 1 and Comparative Examples 1, 3, and 5 had good blow moldability.

  Next, after putting chemicals (bactericidal solution) into four types of plastic bottles (Example 1 and Comparative Examples 1, 3, 5) excluding Comparative Examples 2 and 4 and sterilizing them, green tea was added in an aseptic atmosphere. Filled. At this time, the temperature of the green tea was 30 ° C. Next, sterilized liquid nitrogen (LN2) 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, about each plastic bottle, the depth (distance t1 ') of the center part and the bottle internal pressure were measured (refer Table 1).

  As a result, the plastic bottle 10 of Example 1 was upright (t1 ′> 0 mm) and had good blow moldability. On the other hand, the plastic bottles of Comparative Examples 1 and 3 were easily overturned (t1 ′ <0 mm).

  As a result, it can be said that 0.30 <t1 / t2 <1.60 and 0.05 <t3 / t4 <0.35 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,
Aseptic filling the bottle with the content liquid, adding 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 0.30 <t1 / t2 <1.60 and 0.05 <t3 / t4 <0.35.   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 0.25 mm.   The plastic bottle according to any one of claims 1 to 3, wherein a filling temperature of the content liquid is 10 ° C to 40 ° C.

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