JP2012140154A - Plastic bottle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plastic bottle which is filled with content liquid aseptically and can prevent buckling of a bottom part even when inside pressure is made positive pressure.SOLUTION: The plastic bottle 10 includes a mouth portion 11, a neck portion 12, a body portion 20, and the bottom part 30. The bottom part 30 has a petaloid shape having a center part 31 located at the center thereof, and a plurality of petaloid feet 32 radially extending from the center part 31 to a peripheral edge part 30b. The central part 31 has an annular surface 34, and a recessed portion 35 recessed inward from the annular surface 34. The plastic bottle 10 is filled with the content liquid 15 aseptically, and liquefied gas is added thereto. Consequently, the buckling of the bottom part 30 can be prevented, when the inside pressure of the plastic bottle 10 is made the positive pressure.

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 provides a plastic bottle including a mouth, a neck, a body, and a bottom, wherein the bottom includes a central portion located in the center, and a plurality of petaloid legs extending radially from the central portion to the peripheral portion. A plastic having a petaloid shape, a central portion having an annular surface and a recess recessed inwardly from the annular surface, wherein the bottle is aseptically filled with content liquid and liquefied gas is added. It is a bottle.

  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 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.

  In the present invention, 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. The plastic bottle is characterized in that 10 <t2 / t1 <0.50 and 0.15 <t3 / t4 <0.35.

  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 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. Accordingly, even when the inside of the bottle is set to a positive pressure, deformation of the bottom can be reduced, 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, by providing a recess at the center of the bottom, the unstretched portion at the center of the bottom is reduced to relieve stress, and the resin does not accumulate in the center of the bottom. Resin will accumulate. Thereby, the malfunction which the leg tip of a petaloid leg collapses 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. 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 vertical end view showing the 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 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 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.

  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.

  As shown in FIG. 2 and FIG. 5, the concave portion 35 has a smooth curved surface as a whole, and has a smooth curved surface without providing a convex portion at the center of the bottom center portion in the concave portion 35. Thereby, when the inside of a bottle is made into a positive pressure, it has the structure where the recessed part 35 cannot be reversed easily.

  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, 0.10 <t2 / t1 < It is preferably 0.50. In addition, when t2 / t1 ≧ 0.50, 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 ≦ 0.10, 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 0.15 <t3 / t4 <0.35 (see FIG. 6A). When t3 / t4 ≧ 0.35, 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 ≦ 0.15, since the diameter t3 of the recess is short, it is difficult to obtain the effect of preventing the buckling of the bottom 30 (see FIG. 6C). For this reason, it is preferable that 0.10 <t2 / t1 <0.50 and 0.15 <t3 / t4 <0.35.

  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, 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.

  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 by dropping after aseptic filling. 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 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. 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 0.30. 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 0.25. 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 wall thickness as in Example 1 (comparison) except that the ratio (t2 / t1) of the distance t2 to the distance t1 was set to 0.10. Example 1) was prepared.

(Comparative Example 2)
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 0.50. 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 0.15. 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 0.35. Example 4) was prepared.

(Comparative Example 5)
A plastic bottle 50 (Comparative Example 5) for 500 ml having the configuration shown in FIG. 7 was produced. In this case, a plastic bottle 50 (Comparative Example 5) was produced by biaxially stretching blow molding a 28 g preform.

  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 is upright (t1 ′> 0 mm), has good blow moldability, and has the same performance as the plastic bottle 50 (Comparative Example 5) having a weight of 28 g. Had. 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 it is preferable to satisfy 0.10 <t2 / t1 <0.50 and 0.15 <t3 / t4 <0.35.

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 (7)

In a plastic bottle with a mouth, a neck, a torso, and a bottom,
The bottom has a petaloid shape having a central part located in the center and a plurality of petaloid legs extending radially from the central part to the peripheral part,
The central portion has an annular surface and a recess recessed inward from the annular surface,
A plastic bottle characterized in that the liquid inside is aseptically filled and a liquefied gas is added.   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.   When the distance between the bottom of the recess and the ground contact part 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, 0.10 <t2 / 5. The plastic bottle according to claim 1, wherein t1 <0.50 and 0.15 <t3 / t4 <0.35.   The plastic bottle according to any one of claims 1 to 5, 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 6, wherein the filling temperature of the content liquid is 10 ° C to 40 ° C.

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