JP7681380B2 - Anti-foam bottom of plastic bottle - Google Patents

Description

The present invention relates to the bottom of a plastic bottle, and more specifically to a bottom that prevents foaming of the plastic bottle when a liquid is filled into a plastic bottle supported at an angle using a rotary filling device.

As is well known, bottle-shaped containers, such as plastic bottles, are widely used as containers for storing liquid contents, such as various beverages, etc. As a method for filling such bottle-shaped containers with liquid contents, a rotary filling device that rotates a cylindrical drum-shaped filling machine at high speed to increase production efficiency is known.
In a rotary filling device, the liquid is discharged from the filling nozzle and filled into the container while the disk is rotating, so that the liquid column is deflected outward from the rotor by centrifugal force and lands on the outside of the bottom of the container. In the case where the bottom of the container is formed in a convex shape in the center and a concave shape on the outer periphery, there is a problem that when the filled liquid directly hits the concave shape on the outside, it splashes up significantly and causes a large amount of foaming.

A rotary filling device that suppresses foaming during filling has been proposed (see Patent Document 1). In this rotary filling device, in order to drop the liquid to the center of the bottom of the container, the container holder supports the container so that it is tilted downward toward the outer periphery of the disk at an inclination angle θ with respect to the discharge direction of the liquid discharged vertically downward from the filling nozzle. Note that this inclination angle θ is generally determined by the diameter of the rotation path of the filling valve of the rotary filling device, the production capacity (the number of containers that can be filled with liquid per minute), and the number of filling valves, and is known to be around 3 to 6 degrees.

However, because the measures taken in the rotary filling device described above were insufficient to prevent foaming, it was necessary to increase the head space (remaining air space) S as a measure to prevent foam spilling over the mouth of the container when the liquid contents are filled up to the mouth of the container and to prevent the mouth from becoming dirty (see Figure 8 (b)). If this head space S is large, oxidation of the liquid contents will be promoted and the amount of liquid contents will appear to be small, so measures to prevent foaming and further reduce the head space S must also be taken into account in the structure of the container to be filled.

As a solution to this problem, for example, the container bottom structure of Patent Document 2 has been proposed. In the container bottom structure of Patent Document 2, the lower end of the body that constitutes the outer peripheral wall of the container is closed by the bottom. This bottom comprises a grounding portion formed in an annular shape and a convex portion formed at the center position within the grounding portion. An annular convex portion is formed between the grounding portion and the convex portion, and an annular concave portion is formed adjacent to the annular convex portion.

JP 2006-248547 A JP 2015-205726 A

However, the technology described in Patent Document 2 attempts to prevent splashing and foaming by reducing the force of the flow of the liquid when it passes over the annular convex portion and colliding with the body, but there is a concern that the liquid will rise up the slope of the annular convex portion and branch toward the inner wall of the body and toward the ground, and that the liquid that branches toward the inner wall of the body will collide with the inner wall of the body along the slope of the annular convex portion and be splashed up, causing increased foaming.

The object of the present invention is to provide a foam-preventing bottom for a plastic bottle that prevents foaming when a plastic bottle supported at an angle is filled with liquid using a rotary filling device.

In order to solve the above problems, the foam-preventing bottom of a plastic bottle of the present invention has a bottom having a flat surface in the center of the bottom, a ground contact portion located on the periphery of the bottom, and a connecting portion connecting the outer periphery of the flat surface to the inner periphery of the ground contact portion, the connecting portion having a first inclined portion that inclines from the flat surface toward the ground contact portion via a first step portion, a second inclined portion that inclines from the first inclined portion toward the ground contact portion via a second step portion, a plane portion that is continuous with the second inclined portion and extends toward the ground contact portion, and a third inclined portion that inclines from the plane portion toward the ground contact portion via a third step portion, the first inclined portion, the second inclined portion, and the third inclined portion are inclined surfaces that are generally arc-shaped and recessed downward, and the inclined surface is The bottle has a structure in which the bottle does not bulge downward from a horizontal plane including the outer peripheral edges of the inclined portion, the second inclined portion, or the third inclined portion, the radial length of the first inclined portion is greater than the radial lengths of the second inclined portion and the third inclined portion, and the radial length of the flat portion is greater than the radial length of the third inclined portion, the height of the first inclined portion in the bottle axial direction is greater than the heights of the second inclined portion and the third inclined portion, a connection portion between the second inclined portion and the flat portion is recessed downward in a V-shape, and the flat surface is formed so that a ratio D1/D2 of a diameter D1 of the flat surface to a maximum diameter D2 of a body portion connected above the bottom is 0.05 to 0.30 .

Furthermore, the flat surface is formed so that the ratio D1/D2 of the diameter D1 of the flat surface to the maximum diameter D2 of the body portion connected above the bottom portion is 0.10 to 0.25 .

Furthermore, the first inclined portion, the second inclined portion, and the third inclined portion are formed so that the ratio of the height of the first inclined portion, the second inclined portion, or the third inclined portion in the bottle axial direction to the total height of the plastic bottle is 0.02 to 0.1 .

Furthermore, the inclination angle between an extension line of the ground contact portion and a tangent to the inclined surface of the maximum curvature of the first inclined portion , the second inclined portion, or the third inclined portion is 20 to 50 degrees.

According to the foam-preventing bottom of a plastic bottle of the present invention, the bottom has a flat surface in the center of the bottom, a ground contact portion located on the periphery of the bottom, and a connecting portion connecting the outer periphery of the flat surface to the inner periphery of the ground contact portion, the connecting portion having a first inclined portion that inclines from the flat surface toward the ground contact portion via a first step portion, a second inclined portion that inclines from the first inclined portion toward the ground contact portion via a second step portion, a plane portion that is continuous with the second inclined portion and extends toward the ground contact portion, and a third inclined portion that inclines from the plane portion toward the ground contact portion via a third step portion, the first inclined portion, the second inclined portion, and the third inclined portion are inclined surfaces that are generally arc-shaped and recessed downward, and the inclined surface bulges downward from a horizontal plane including the outer periphery of the first inclined portion, the second inclined portion, or the third inclined portion. the radial length of the first inclined portion is greater than the radial lengths of the second inclined portion and the third inclined portion, and the radial length of the flat portion is greater than the radial length of the third inclined portion, the height of the first inclined portion in the bottle axial direction is greater than the height of the second inclined portion and the third inclined portion in the bottle axial direction, the connecting portion between the second inclined portion and the flat portion is V-shaped and recessed downward , and the flat surface is formed so that the ratio D1/D2 of the diameter D1 of the flat surface to the maximum diameter D2 of the body portion connected above the bottom is 0.05 to 0.30, so that when a liquid is filled into a plastic bottle supported at an angle using a rotary filling device, the flow rate of the content liquid is gradually attenuated as it flows through the connecting portion,
Since the liquid content passes through the grounded portion before colliding with the inner wall of the body, splashing is kept small and foaming can be prevented.

Furthermore, according to the foam-preventing bottom of the plastic bottle of the present invention, the flat surface is formed so that the ratio D1/D2 of the diameter D1 of the flat surface to the maximum diameter D2 of the body portion connected above the bottom is 0.10 to 0.25 , which makes it easy to align the filling nozzle in a rotary filling device and allows the content liquid to hit the flat surface once and attenuate the flow rate.

Furthermore, according to the foam-preventing bottom of the plastic bottle of the present invention, the first inclined portion, the second inclined portion, and the third inclined portion are formed so that the ratio of the height of the first inclined portion, the second inclined portion, or the third inclined portion in the bottle axial direction to the total height of the plastic bottle is 0.02 to 0.1 , so that the flow rate of the content liquid is gradually attenuated as it flows through the connecting portion, thereby preventing foaming.

Furthermore, according to the foam-preventing bottom of the plastic bottle of the present invention, the inclination angle between the extension line of the grounded portion and the tangent to the inclined surface of the maximum curved portion of the first inclined portion, the second inclined portion or the third inclined portion is 20 to 50 degrees, so that the flow rate of the content liquid is gradually attenuated as it flows through the connecting portion, thereby preventing foaming.

FIG. 2 is a front view showing an example of a plastic bottle equipped with a foam-preventing bottom according to the present embodiment. FIG. 2 is a plan view of the plastic bottle of FIG. 1. FIG. 2 is a bottom view of the plastic bottle of FIG. 1. FIG. 3 is a view taken in the direction of the arrow I in FIG. 2 . 4A is a partially enlarged cross-sectional view taken along line II-II in FIG. 3, and FIG. 4B is a partially enlarged cross-sectional view taken along line III-III in FIG. FIG. 5B is an enlarged partial cross-sectional view of FIG. FIG. 1A is an image showing the flow of liquid when a plastic bottle according to the present embodiment is supported at an angle and filled with liquid using a rotary filling device; FIG. 1B is an image showing the flow of liquid when a conventional plastic bottle is supported at an angle and filled with liquid using a rotary filling device. 1A is a schematic diagram showing how a plastic bottle supported at an angle is filled with liquid using a rotary filling device, and FIG. 1B is a front view of the plastic bottle after filling with the liquid has been completed. FIG. 2 is an enlarged cross-sectional view taken along line IV-IV in FIG. This is an enlarged partial cross-sectional view taken along line VV in Figure 1. The arrow direction indicates the outside of the plastic bottle. FIG. 2 is an enlarged view of a circumferential groove portion of the plastic bottle of FIG. 1 . FIG. 2 is a schematic plan view illustrating a rotary filling device. FIG. 2 is a front view of a plastic bottle of a comparative example. FIG. 14 is a plan view of the plastic bottle of FIG. 13. FIG. 14 is a bottom view of the plastic bottle of FIG. 13. FIG. 16 is an enlarged partial cross-sectional view taken along line VI-VI in FIG. 1 is a modified example of a plastic bottle having a foam-preventing bottom according to the present embodiment.

The details of the embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a front view showing an example of a plastic bottle equipped with a foam-preventing bottom of the plastic bottle 1 according to this embodiment. Fig. 2 is a plan view of the plastic bottle 1 in Fig. 1, and Fig. 3 is a bottom view of the plastic bottle 1 in Fig. 1. Fig. 4 is a view seen from the direction of the arrow I in Fig. 2. For ease of explanation, in the following description, the mouth 10 of the plastic bottle 1, where the contents are filled into the container, is considered to be on the top when the plastic bottle 1 is in the upright position shown in Fig. 1.

As shown in Figures 1 to 5, the foam prevention bottom of the plastic bottle 1 according to this embodiment has a bottom 40 having a flat surface 42 in the center of the bottom 40, a grounding portion 41 located on the periphery of the bottom 40, and a connecting portion 43 connecting the outer peripheral edge 42d of the flat surface 42 to the inner peripheral edge 41a of the grounding portion 41. The connecting portion 43 has a vertical cross section perpendicular to the bottle axis 11 having a plurality of inclined portions 44a, 44b, and 44c that incline stepwise downward from the outer peripheral edge 42d of the flat surface 42 toward the grounding portion 41 side. The inclined portions 44a, 44b, and 44c are inclined surfaces that are generally arc-shaped and recessed downward. The inclined surfaces do not bulge downward from a horizontal plane including the outer peripheral edges of the inclined portions 44a, 44b, and 44c, and a flat portion 45 is provided between adjacent inclined portions 44a, 44b, and 44c.

Below, as an example of a suitable embodiment of the plastic bottle 1 according to this embodiment, a square bottle with a substantially rectangular horizontal cross section will be exemplified and described in detail. There are no particular limitations on the bottle having the above-described configuration of the bottom 40, except for the bottom shape, and it may be a round bottle with a circular cross section of the body of the container, or a square bottle with a substantially square cross section of the body of the container.

The plastic bottle 1 according to this embodiment has a mouth 10, a shoulder 20, a body 30, and a bottom 40. The mouth 10 serves as a filling port for the contents, a pouring outlet, or a drinking spout, and the plastic bottle 1 is sealed by attaching a lid (not shown) to the mouth 10.

The upper side of the shoulder portion 20 is connected to the mouth portion 10, while the lower side is connected to the body portion 30. The shoulder portion 20 has a shape of a truncated quadrangular pyramid that expands in diameter from top to bottom. As shown in FIG. 2, since the plastic bottle 1 is a rectangular bottle, the shoulder portion 20 is composed of four surfaces, which are, in a clockwise direction, shoulder portions 20A, 20B, 20C, and 20D. More specifically, the shoulder portion 20 has four shoulder wall portions 21 of the same shape, and a shoulder corner portion 22 is formed between adjacent shoulder wall portions 21. In the following, one surface including the shoulder portion 20A will be described, and, as necessary, the symbols A to D will be appropriately assigned to each portion of the four surfaces in the circumferential direction as described above.

The shoulder section 20 and the torso section 30 are made up of multiple walls 51 and corners 52 that connect the walls 51 together. The walls 51 are divided into a shoulder wall section 21 and a torso wall section 31. The torso wall section 31 is further divided into an upper torso wall section 31E and a lower torso wall section 31F. The corners 52 are divided into a shoulder corner section 22 and a torso corner section 32. The torso corner section 32 is further divided into an upper torso corner section 32E and a lower torso corner section 32F.

The shoulder portion 20 is connected to the upper body wall portion 31E and the upper body corner portion 32E in detail. From the viewpoint of improving the strength of the shoulder portion 20, it is preferable that the shoulder wall portion 21 is formed by two panels 21a, 21b divided in the vertical direction. From the viewpoint of improving the strength, it is preferable that the vertical division is on a line extending upward through approximately the horizontal center of the wall portion 51. On the other hand, the shoulder corner portion 22 may be formed by a single panel.

Next, it is preferable to provide multiple vertical ribs 53 across the circumferentially extending ridge 50 where the shoulder 20 transitions to the body 30, from the viewpoint of preventing so-called shoulder collapse, in which the portion near the ridge 50 where the shoulder 20 transitions to the body 30 is dented due to an external impact, and from the viewpoint of increasing the vertical buckling strength. Also, from the viewpoint of appropriately exerting this effect, it is preferable to provide the vertical ribs 53 on a line extending vertically through approximately the horizontal center of the wall 51 and the corner 52.

The vertical rib 53 may be a groove shape with a V-shaped cross section in which the groove side faces intersect at a linear groove bottom 55, a groove shape with a groove bottom 55 of a predetermined width, a groove shape with a trapezoidal cross section in which the groove side faces rise from both widthwise edges of the groove bottom 55, or a concave cross section with an arc shape.

With this configuration, when an external force is applied to the area near the ridge line 50 that extends in the circumferential direction where the shoulder portion 20 transitions to the body portion 30, the area near the ridge line 50 is pushed inward into the bottle and deformed, causing a fold line to form in a direction perpendicular to the height direction. By providing a vertical rib 53 perpendicular to this fold line, a restoring force can be exerted against such shape changes, and permanent deformation can be prevented near the ridge line 50 where the shoulder portion 20 of the plastic bottle 1 transitions to the body portion 30. In other words, shoulder collapse can be prevented and the vertical buckling strength can be increased.

Furthermore, the upper end 54 of the vertical rib 53 is preferably a concave rib provided at a position 0.5 to 4.0 mm vertically above the ridge line 50. Furthermore, adjacent vertical ribs 53 in the circumferential direction of the wall portion 51 are preferably provided at equal intervals of 2 to 6 mm. Furthermore, the vertical ribs 53 of the wall portion 51 and the corner portion 52 are each provided with an odd number of vertical ribs 53, and in particular, it is preferable that the vertical ribs 53 of the wall portion 51 are each formed with 5 to 15 pieces.

Next, the body wall 31 of the plastic bottle 1 will be described in detail. The body wall 31 is preferably divided into an upper body wall 31E and a lower body wall 31F at approximately the middle in the vertical direction, each of which is provided with a pressure absorption panel 35. The pressure absorption panel 35 absorbs pressure changes, particularly decompression changes, inside the plastic bottle 1, and maintains the strength of the plastic bottle 1, particularly the side wall strength. The pressure absorption panel 35 will be described below, but because the upper body wall 31E and the lower body wall 31F have the same configuration, only the lower body wall 31F will be described and the configuration of the upper body wall 31E will be omitted.

As shown in Figures 1, 9 and 10, the pressure absorption panel 35 of the lower body wall portion 31F has a stepped body wall surface 33a that is recessed one step inward from the outermost surface of the lower body wall portion 31F, and a stepped body wall surface 33b that is convex one step outward from the stepped body wall surface 33a. The panel inclined portion 34b is formed via a chamfered portion 37d so as to surround the periphery of the stepped body wall surface 33b, the stepped body wall surface 33a is formed via a chamfered portion 37c so as to surround the periphery of the panel inclined portion 34b, the panel inclined portion 34a is formed via a chamfered portion 37b so as to surround the periphery of the stepped body wall surface 33a, and the outermost surface of the lower body wall portion 31F is connected via a chamfered portion 37a so as to surround the periphery of the panel inclined portion 34a.

The depth s1 from the outermost surface of the lower body wall portion 31F to the stepped body wall surface 33a is 0.5 to 4.0 mm, preferably 1.0 to 3.0 mm, and the depth s2 from the stepped body wall surface 33b to the stepped body wall surface 33a is 0.2 to 3.0 mm, preferably 0.5 to 2.0 mm. There is a relationship between s1 and s2, s1 > s2, and if the depth s1 is small, it becomes difficult to absorb the load caused by the change in the internal pressure of the plastic bottle 1, while if the depth s1 is large, poor shaping and whitening due to overstretching are likely to occur during molding of the plastic bottle 1.

Plastic bottle 1 has a small degree of oxygen permeability. If the contents are stored in plastic bottle 1 for a long period of time, oxidation will occur depending on the liquid contained, causing the pressure inside plastic bottle 1 to decrease. In addition, the pressure inside plastic bottle 1 will change depending on the temperature difference between when the contents are filled and when the bottle is stored. When the pressure inside plastic bottle 1 decreases, it will be pulled inward and deformed.

At this time, the pressure absorption panel 35 easily deforms inward as the stepped body wall surfaces 33a, 33b are stretched. When the pressure inside the plastic bottle 1 is reduced, the pressure absorption panel 35 recesses inward into the plastic bottle 1, thereby preventing the entire plastic bottle 1 from deforming. Furthermore, the stress applied to the plastic bottle 1 is dispersed by the uneven parts, increasing the rigidity of the wall surface 51 and preventing the bottle from bulging.

The pressure absorption panel 35 also serves to prevent the entire plastic bottle 1 from deforming when the pressure inside the plastic bottle 1 is increased. The pressure absorption panel 35 having this configuration can also prevent the walls of the plastic bottle 1 from being pressed inward when the plastic bottle 1 is opened, causing the contents to be pushed out of the mouth 10 and spill. The pressure absorption panel 35 can also increase the rigidity of the body 30.

Here, if the panel of the stepped barrel wall surface 33b is a flat surface, deformation will be significant when the bottle is held in it. Therefore, it is preferable to have multiple horizontal ribs 36 extending horizontally over the entire area of the panel of the stepped barrel wall surface 33b in the vertical direction from the top to the bottom. As described above, it is preferable to have multiple horizontal ribs 36 extending horizontally within the panel surrounded by the stepped barrel wall surface 33b, but it is also possible to have concave or convex ribs (not shown) extending in any direction. Furthermore, the horizontal ribs 36 may be formed only in a part of the panel surrounded by the stepped barrel wall surface 33b, for example, only the upper half, lower half, or the central part in the vertical direction.

However, if there are too many horizontal ribs 36, the pressure absorption panel 35 will be less likely to deform inwardly of the plastic bottle 1, and the pressure absorption function will be lost. Therefore, the number and dimensions of the horizontal ribs 36 are appropriately designed.

It is preferable that four to ten horizontal ribs 36 are provided within the panel surrounded by the stepped body wall surface 33b. By providing four or more horizontal ribs 36, the vacuum absorption function can be fully exerted, the rigidity of the body wall portion 31 is increased, the pressure applied to the plastic bottle 1 is dispersed, and the effect of preventing bottle bulging can be fully obtained. On the other hand, if there are 11 or more horizontal ribs 36, the vacuum absorption function is impaired.

The upper body wall 31E of the plastic bottle 1 is the part where a label is attached. The label is attached by, for example, a shrink label, which is made by applying hot air to a cylindrical heat-shrinkable film such as polystyrene (PS) or polyethylene terephthalate (PET) that is placed over the plastic bottle 1 and shrinking it. Since the dimensions of the cylindrical heat-shrinkable film are set to a predetermined value, if the upper body wall 31E is bulging, problems will occur such as the heat-shrinkable film becoming clogged or not being able to be inserted.

Therefore, it is preferable that the pressure absorbing panel 35 is configured so that it does not protrude outward from the outermost surface of the upper body wall 31E of the plastic bottle 1. In other words, it is preferable that the stepped body wall surface 33b is located inward from the outermost surface of the upper body wall 31E, and the horizontal rib 36 provided within the panel surrounded by the stepped body wall surface 33b is a concave rib. This allows for smooth attachment of the label to the upper body wall 31E, and also improves the loading efficiency of boxing into cardboard boxes, etc., thereby improving productivity. Furthermore, by providing the pressure absorbing panel 35, the appearance of the product filled with the contents in the plastic bottle 1 can be maintained in good condition, and a decrease in the product value can be prevented.

The width a of the stepped barrel wall surface 33a shown in FIG. 9 is preferably set to 0.5 mm≦a≦5.0 mm. Since the stepped barrel wall surface 33a will have an uneven shape in the blow molding die, setting the width a to 0.5 mm≦a makes it easier to shape the stepped barrel wall surface 33a during blow molding. On the other hand, setting the width a of the stepped barrel wall surface 33a to a≦5.0 mm allows it to fully exert its vacuum absorption function and reinforcing function.

The angles θ2 and θ1 of the panel inclined portions 34a and 34b are preferably in the range of 15 degrees ≦ θ2 ≦ 60 degrees and 15 degrees ≦ θ1 ≦ 60 degrees from the viewpoint of blow moldability and releasability after molding. Note that θ2 and θ1 may all be set to the same value θ2 = θ1.

In addition, in one pressure absorption panel 35, each dimension s1, s2, a, θ1, θ2, etc. can be appropriately designed to have different values that satisfy the above-mentioned relationships. Furthermore, the configuration of the pressure absorption panel 35 and horizontal ribs 36 of the lower body wall portion 31F described above can be arbitrarily combined with the configuration of the pressure absorption panel 35 and horizontal ribs 36 of the upper body wall portion 31E to the extent that there is no contradiction.

As shown in FIG. 11, it is preferable to have an annular circumferential groove 38 between the upper body wall portion 31E and the lower body wall portion 31F, which crosses the body wall portion 31 and the body corner portion 32. The circumferential groove 38 improves the sidewall strength, which is the strength to withstand horizontal loads on the body portion 30.

The configuration of the circumferential groove 38 will now be described in detail. The circumferential groove 38 is formed so that it becomes wider from both ends of the trunk corner portion 32 toward the center. In other words, the width c2 of the circumferential groove 38 at the center of the trunk corner portion 32 is greater than the width c1 of the circumferential groove 38 at both ends of the trunk corner portion 32. This configuration can increase the rigidity of the trunk portion 30.

From the viewpoints of buckling strength and formability, it is preferable that the ratio of c2/c1 is 1.05 to 2.50. If the ratio of c2/c1 is less than 1.05, it becomes difficult to prevent stress concentration. On the other hand, if the ratio of c2/c1 is greater than 2.50, it becomes a bending point when a vertical load is applied.

The lower body wall 31F has a horizontally extending groove 39 below the pressure absorbing panel 35 and close to the bottom 40, and both ends of the groove 39 do not extend to both ends of the wall 51. With this configuration, the liquid contents filled into the bottle from the mouth 10 hits the flat surface 42 of the bottom 40 (described below), and then flows from the flat surface 42 toward the grounding part 41. As it rises along the inner wall of the body, it comes into contact with the groove 39 that is recessed inward near the bottom 40, preventing significant turbulence and preventing foaming.

Next, the bottom 40 of the plastic bottle 1 will be described in detail with reference to FIG. 3 and FIG. 5. The bottom 40 includes a flat surface 42 in the center of the bottom 40, a grounding portion 41 located on the periphery of the bottom 40, and a connecting portion 43 connecting the outer peripheral edge 42d of the flat surface 42 to the inner peripheral edge 41a of the grounding portion 41. The connecting portion 43 has a plurality of inclined portions 44a, 44b, 44c formed in a vertical section perpendicular to the bottle axis 11, the inclined portions 44a, 44b, 44c being inclined downward in stages from the outer peripheral edge 42d of the flat surface 42 toward the grounding portion 41. The inclined portions 44a, 44b, 44c are inclined surfaces having a substantially arcuate shape recessed downward, and the inclined surfaces do not bulge downward from a horizontal plane including the outer peripheral edges of the inclined portions 44a, 44b, 44c, and are characterized in that a flat portion 45 is provided between adjacent inclined portions 44a, 44b, 44c.

The periphery of the grounding part 41 is generally rectangular, and the short side of the rectangle is generally arc-shaped. The shape of the periphery of the grounding part 41 is not limited to this configuration, and may be, for example, a polygonal shape such as a hexagon, a circular shape, an elliptical shape, etc.

The connecting portion 43 has a three-stage inclination: a first inclined portion 44a that inclines from the outer peripheral edge 42d of the flat surface 42 toward the ground contact portion 41; a second inclined portion 44b that continues from the outer peripheral edge of the first inclined portion 44a and inclines toward the ground contact portion 41; a flat portion 45 that continues from the outer peripheral edge of the second inclined portion 44b and extends toward the ground contact portion 41; and a third inclined portion 44c that continues from the outer peripheral edge of the flat portion 45 and inclines toward the inner peripheral edge 41a of the ground contact portion 41.

Here, the flat surface 42 is preferably formed in a range in which the ratio D1/D2 of the diameter D1 of the flat surface 42 to the maximum diameter D2 of the body 30 is 0.05 to 0.30. If this range is too small, the range in which the liquid content W can reach will be narrow, making it necessary to align the filling nozzle 2 in the rotary filling device 5 shown in Figures 8(a) and 12, and the liquid content W will be less likely to hit the flat surface 42, and once it hits the flat surface 42, the function of attenuating the flow rate will not be fully realized. If the formation range is too large, the range in which the liquid contents W can reach will be wide, and the filling nozzle 2 in the rotary filling device 5 can be easily aligned, but the range of the connecting portion 43 will be narrow, and it will be impossible to secure sufficient space to provide the three-stage inclined portions 44a, 44b, 44c or the flat portion 45. As the liquid contents W flows through the connecting portion 43, the flow rate is not attenuated in stages and it collides with the inner wall of the body, making it impossible to suppress splashing and preventing foaming.

The flat surface 42 is preferably circular, but may be polygonal, such as a hexagon, or elliptical, depending on the size and shape of the bottle. As a modification of this embodiment, the flat surface 42 in the center of the bottom 40 may have an inverted dome-shaped recess 42e in the center, as shown in FIG. 17. With this configuration, the stretch rod used when blow molding a plastic bottle fits nicely into this inverted dome-shaped recess 42e, making it easier to mold the bottle.

As shown in Figures 5(a) and 5(b), the inclined portions 44a, 44b, and 44c are preferably formed such that the ratios H3/H1, H4/H1, and H5/H1 of the heights H3, H4, and H5 of the first inclined portion 44a, the second inclined portion 44b, and the third inclined portion 44c in the direction of the bottle axis 11 relative to the total height H1 of the plastic bottle 1 are 0.02 to 0.25, from the viewpoint of gradually attenuating the flow rate of the content liquid W as it flows through the connecting portion 43 and preventing foaming.

As shown in FIG. 6, the inclination angles α, β, and γ between the extension line of the ground contact portion 41 and the tangent line at the inclined surface of the maximum curved portion of the first inclined portion 44a, the second inclined portion 44b, and the third inclined portion 44c are preferably 15 to 60 degrees from the viewpoint of gradually attenuating the flow rate of the content liquid W as it flows through the connecting portion 43 to prevent foaming. Furthermore, it is more preferable that the inclination angles α, β, and γ have a relationship of β≧α>γ. If α>β>γ or α>β, there is no problem if the flow rate of the content liquid W during filling is fast, but if the flow rate is slow, the filling gradually catches up, causing the content liquid W to become clogged and causing excessive foaming.

The heights H3, H4, and H5 of the inclined portions 44a, 44b, and 44c in the direction of the bottle axis 11 and the inclination angles α, β, and γ of the tangents of the inclined surfaces of the maximum curved portions of the inclined portions 44a, 44b, and 44c relative to the extension line of the ground contact portion 41 can be appropriately designed in consideration of the size of the bottle, etc.

Next, in the configuration of the bottom 40 of a conventional plastic bottle and the configuration of the bottom 40 of the plastic bottle of this embodiment, the flow of the liquid W filled in the bottle supported so as to be inclined at an inclination angle θ toward the outer periphery of the wheel 7 (see FIG. 12) downward with respect to the discharge direction of the liquid W discharged vertically downward from the filling nozzle 2 (see FIG. 8(a)) using the rotary filling device 5 will be described in detail. Note that this inclination angle θ is preferably about 3 to 6 degrees, and can be appropriately adjusted depending on the diameter of the rotation path of the filling valve 2 of the rotary filling device 5, the production capacity (the number of containers that can be filled with liquid per minute), the number of filling valves 2, etc.

As shown in Figures 7, 8 and 12, after the content liquid W hits the flat surface 42 of the bottom 40 of the bottle, it flows from the tangent 42c of the circle 42b, which is the trajectory of the center 42a of the flat surface 42 of the bottle in the rotary filling device 5, through the connecting portion 43 on the wheel axle 6 side toward the grounding portion 41 (hereinafter referred to as "flowing inward"), and from the tangent 42c of the circle, it flows from the connecting portion 43 on the opposite side to the wheel axle 6 side toward the grounding portion 41 (hereinafter referred to as "flowing outward").

As shown by the arrow in Figure 7 (b), according to the configuration of the bottom 40 of a conventional plastic bottle, the content liquid W flows along the curved shape of the entire bottom 40, and without slowing down in flow speed, it hits the inner wall of the body 30 from the ground contact part 41 and splashes upward in the bottle, causing large splashes and foaming. In addition, because the bottle is supported at an inclination angle θ, when the liquid flows outward, the inclination is gentler than when the liquid flows inward, so the flow speed is slower and foaming is less likely to occur.

On the other hand, as shown by the arrow in FIG. 7(a), according to the configuration of the bottom 40 of the plastic bottle of this embodiment, when the liquid content W flows inward, the liquid content W hits the flat surface 42 of the bottom 40 of the bottle, which is inclined at an inclination angle θ, and then flows down the upper surface of the flat surface 42 toward the ground side, and is decelerated at the first step 46a, which is the boundary between the flat surface 42 and the first inclined portion 44a, by the step acting as a dam. Then, the liquid content W further flows down the first inclined portion 44a and flows between the first inclined portion 44a and the second inclined portion 46a. The flow is slowed down at the second step 46b, which is the boundary between the first and second inclined portions 44b, by the step acting as a dam, and then flows down the second inclined portion 44b, and the acceleration weakens as the flow flows through the flat portion 45, which has a gentler inclination than the second inclined portion 44b. The flow is slowed down at the third step 46c, which is the boundary between the flat portion 45 and the third inclined portion 44c, by the step acting as a dam, and then flows down the third inclined portion 44c, passing through the ground portion 41 at a flow rate that is gradually attenuated, and colliding with the inner wall of the body 30. Here, the step acts as a dam to attenuate the flow rate because the bottle is tilted by the inclination angle θ when filled using the rotary filling device 5.

In addition, the generally arc-shaped inclined surface recessed below the inclined portions 44a, 44b, and 44c does not bulge below the horizontal plane including the outer periphery of the inclined portions 44a, 44b, and 44c, so the liquid contents W do not ascend the gradient of the inclined surface, but branch toward the inner wall of the body due to the momentum of the ascending flow rate, and collide with the inner wall of the body, preventing increased foaming due to splashing. In other words, the liquid contents W passes through the grounding portion at a flow rate that is gradually attenuated while flowing through the above-mentioned connecting portion 43, and then collide with the inner wall of the body, so splashing is kept small and foaming can be prevented.

Furthermore, because flat portions 45 are provided between adjacent inclined portions 44a, 44b, 44c, the flow rate of the content liquid can be further attenuated as it flows through the connecting portion 43. Therefore, without lowering the filling nozzle 2 or slowing down the production speed, foaming can be reduced when the content liquid is filled into the plastic bottle 1 while maintaining the production speed. In addition, by minimizing foaming during filling, the head space S of the plastic bottle 1 can be reduced, and oxidation of the content liquid in the plastic bottle 1 can also be suppressed.

Next, when the liquid contents W flow outward, because the bottle is supported at an inclination angle θ, the inclination is gentler than when the liquid flows inward, resulting in a slower flow rate and less foaming.

Furthermore, as shown in Figures 3 and 5, reinforcing ribs 48 are formed radially from the outer peripheral edge 42d of the flat surface 42 to the inner peripheral edge 41a of the ground contact portion 41 at the connecting portion 43 of the bottom portion 40. Therefore, it is possible to prevent deformation such as inversion of the bottom portion 40 due to internal pressure generated by an impact such as a fall.

The present invention will be explained in more detail below with reference to examples and comparative examples. However, the present invention is not limited to the following examples.

<Materials>
[Examples 1 to 5]
In Examples 1 to 5, the foam-preventing bottom of the plastic bottle 1 according to the present embodiment shown in Figs. 1, 3, and 5 was used. That is, the foam-preventing bottom of the plastic bottle 1 has a bottom 40 having a flat surface 42 in the center of the bottom 40, a ground contact portion 41 located on the periphery of the bottom 40, and a connecting portion 43 connecting from the outer peripheral edge 42d of the flat surface 42 to the inner peripheral edge 41a of the ground contact portion 41, and the connecting portion 43 has a vertical cross section perpendicular to the bottle axis 11 having a plurality of inclined portions 44a, 44b, 44c that slope gradually downward from the outer peripheral edge 42d of the flat surface 42 toward the ground contact portion 41, the inclined portions 44a, 44b, 44c being inclined surfaces that are recessed downwardly and are approximately arc-shaped, the inclined surfaces do not bulge downward below a horizontal plane including the outer peripheral edges of the inclined portions 44a, 44b, 44c, and a flat portion 45 is provided between adjacent inclined portions 44a, 44b, 44c. Plastic bottle 1 was made of polyethylene terephthalate, had a weight of 35 g, and a capacity of 750 ml. Plastic bottle 1 was produced by blow molding a preform. No defective shaping occurred during blow molding.

The plastic bottles of Examples 1 to 5 were shaped as described above, and were evaluated as described below using the values in Table 1 for the ratio D1/D2 of the diameter D1 of the flat surface 42 in each configuration of the bottom 40 to the maximum diameter D2 of the body 30, the ratios H3/H1, H4/H1, H5/H1 of the heights of the inclined portions 44a, 44b, 44c in the bottle axial direction to the total height of the plastic bottle, and the inclination angles α, β, γ between the extension line of the ground contact portion 41 and the tangent to the inclined surface of the maximum curved portion of the inclined portions 44a, 44b, 44c. In the examples, evaluation was performed on plastic bottles with a maximum diameter of the body of the plastic bottle of 75 mm.

[Comparative Example 1]
A 750 ml plastic bottle 100 having a mouth 110, a shoulder 120, a body 130, and a bottom 140 as shown in Figures 13 to 16 was used as Comparative Example 1 for a plastic bottle of conventional shape.

13 is a front view of plastic bottle 100, FIG. 14 is a plan view of plastic bottle 100 in FIG. 13, FIG. 15 is a bottom view of plastic bottle 100 in FIG. 13, and FIG. 16 is an enlarged partial cross-sectional view of plastic bottle 100 taken along line VI-VI in FIG. 15.
The bottom 140 is provided with a flat surface 142 in the center of the bottom 140, a grounding portion 141 located on the periphery of the bottom 140, and an inclined portion 144 whose longitudinal section perpendicular to the bottle axis 11 is inclined downward from an outer peripheral edge 142d of the flat surface 142 toward an inner peripheral edge 141a of the grounding portion 141. The plastic bottle 100 having such a configuration was produced by blow molding a 35 g preform. No defective shaping occurred during the blow molding.

[Comparative Examples 2 to 3]
The plastic bottles of Comparative Examples 2 and 3 were shaped as in Example 1, and were evaluated as described below using the ratio D1/D2 of the diameter D1 of the flat surface 42 in each configuration of the bottom 40 to the maximum diameter D2 of the body 30, the ratios H3/H1, H4/H1, H5/H1 of the heights of the inclined portions 44a, 44b, 44c in the bottle axial direction to the total height of the plastic bottle, and the inclination angles α, β, γ between the extension line of the ground contact portion 41 and the tangent to the inclined surface of the maximum curved portion of the inclined portions 44a, 44b, 44c as shown in Table 1. In Comparative Examples 2 and 3, the evaluation was performed on plastic bottles with a maximum diameter of the body of the plastic bottle of 75 mm.

<Method>
(Foaming test)
The plastic bottles of Examples 1 to 5 and Comparative Examples 1 to 3 were filled with 750 ml of tea-based beverages that easily foam using a rotary filling device 5 shown in Figs. 8 and 12, and liquid and foam portions were generated, and the height of the foam above the liquid surface was measured. The filling valve 8 constituting the rotary filling device 5 is supported vertically by a bracket 9, and the direction of discharging the liquid W from the filling nozzle 2 is also vertically downward (see Fig. 8). In contrast, the support part of the container holder 3 is inclined with respect to the horizontal plane, and the bottle axis 11 of the plastic bottle whose flange part 4 of the container is supported by this support part is inclined downward by an inclination angle θ with respect to the vertical toward the outer periphery of the wheel 7. This inclination angle θ is generally determined by the diameter of the rotation path of the filling valve 8 of the rotary filling device 5, the production capacity (the number of containers that can be filled with liquid per minute), the number of filling valves 8, and the like, and is known to be about 3 to 6 degrees.
As a result, the liquid W discharged vertically downward from the filling nozzle 2 falls substantially along the bottle axis 11 of the plastic bottle 1 due to the centrifugal force generated by the rotation of the wheel 7.

(Measurement results)
A foam height above the liquid surface of 40 mm or more was rated as ×, 20-40 mm as △, 10-20 mm as ◯, and 2-10 mm as ◎. The measurement results (foam height above the liquid surface, evaluation) are shown in Table 1.

As is clear from the evaluation results in Table 1, the foam-preventing bottom of the plastic bottle of each Example had a smaller foam height from the liquid surface during filling than the bottoms of the plastic bottles of Comparative Examples 1 to 3, and it was confirmed that the inclined portion of the connecting portion of the bottom and the flat portion provide excellent foam prevention. In addition, although the bottom of Comparative Example 1 has an inclined portion formed on the bottom, it does not provide sufficient foam prevention effect compared to the other Examples. This is because the bottom of Comparative Example 1 does not have multiple downwardly recessed arc-shaped inclined portions that slope in stages, so the flow rate of the content liquid does not decrease and flows to the body, causing the liquid to splash up.

On the other hand, in Comparative Examples 2 and 3, the ratio D1/D2 of the diameter D1 of the flat surface to the maximum diameter D2 of the body, the ratios H3/H1, H4/H1, H5/H1 of the heights of the inclined portions 44a, 44b, 44c in the bottle axial direction to the total height of the plastic bottle, and the inclination angles α, β, γ between the extension line of the ground contact portion and the tangent to the inclined surface of the maximum curved portion of the inclined portions 44a, 44b, 44c are too small or too large, respectively, so that the flow rate attenuation function of the content liquid in the connecting portion is not well exhibited and the foam prevention effect may be insufficient.

In this way, in order to obtain the good foaming prevention effect described above even in this embodiment, it is preferable to form the flat surface 42 on the bottom 40 so that the ratio D1/D2 of the diameter D1 of the flat surface 42 to the maximum diameter D2 of the body 30 is 0.05 to 0.30, and to form the inclined portions so that the ratios H3/H1, H4/H1, H5/H1 of the heights H3, H4, H5 of the inclined portions 44a, 44b, 44c in the bottle axis 11 direction to the total height H1 of the plastic bottle 1 are 0.02 to 0.25, and the inclination angles α, β, γ between the extension line of the ground contact portion 41 and the tangent to the inclined surface of the maximum curved portion of the inclined portions 44a, 44b, 44c are 15 to 60 degrees.

The present disclosure is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. The foam-preventing bottom of the plastic bottle of the present disclosure is particularly useful for preventing foaming when filling a plastic bottle supported at an angle with a rotary filling device, for example, with a viscous liquid that tends to foam, such as vegetable juice or fruit juice, but can be applied to plastic bottles used to fill any liquid that foams when filled with a rotary filling device into a plastic bottle supported at an angle.

1. Container (plastic bottle)
2 Filling nozzle 3 Container holder 4 Flange portion of container 5 Rotary filling device 6 Wheel shaft 7 Wheel 8 Filling valve 9 Bracket 10 Mouth portion 11 Bottle shaft 20 (20A, 20B, 20C, 20D) Shoulder portion 21 (21a, 21b) Shoulder wall portion 22 Shoulder corner portion 30 Body portion 31 (31E, 31F) Body wall portion (upper body wall portion, lower body wall portion)
32 (32E, 32F) Torso corners (upper torso corners, lower torso corners)
33a, 33b: stepped body wall surface 34a, 34b; panel inclined portion 35; pressure absorbing panel 36; horizontal rib 37 (37a, 37b, 37c, 37d); chamfered portion 38; circumferential groove 39; groove portion 40; bottom portion 41; ground contact portion 41a; inner peripheral edge of ground contact portion 42; flat surface 42a; center of flat surface 42b; circle 42c which is a path through the center of the flat surface; tangent 42d to the circle which is a path through the center of the flat surface; outer peripheral edge 42e of flat surface; inverted dome-shaped recess 43; connected portions 44a, 44b, 44c; inclined portion (first inclined portion, second inclined portion, third inclined portion)
45 Plane section 46 (46a, 46b, 46c) Step section (first step section, second step section, third step section)
48 Reinforcing rib 50 Ridge line 51 Wall portion 52 Corner portion
53 Vertical rib 54 Upper end of vertical rib 55 Groove bottom 100 Plastic bottle (Comparative Example 1)
110 Mouth 120 Shoulder 130 Body 140 Bottom 141 Ground contact portion 141a Inner periphery of ground contact portion 142 Flat surface 142d Outer periphery of flat surface 144 Slope S Head space (remaining air space)
a Width θ of the stepped barrel wall surface 33a Inclination angles θ1, θ2 Angle s1 of the panel inclined portions 34a, 34b Depth s2 of the stepped barrel wall surface 33a from the outermost surface of the lower barrel wall portion Depth H1 from the stepped barrel wall surface 33a to the stepped barrel wall surface 33b Total height H3, H4, H5 of the plastic bottle Height c1 of the first inclined portion, the second inclined portion, and the third inclined portion in the bottle axial direction Width c2 of the circumferential groove at both ends of the barrel corner portion Width D1 of the circumferential groove at the center of the barrel corner portion Diameter D2 of the flat surface Maximum diameters α, β, γ of the barrel portion Inclination angle W between the extension line of the ground contact portion and the tangent to the inclined surface of the maximum curved portion of the first inclined portion, the second inclined portion, and the third inclined portion Contents (liquid)

Claims (4)

The bottom is
a flat surface at the center of the bottom;
a ground portion located on the bottom periphery;
A connecting portion that connects an outer peripheral edge of the flat surface to an inner peripheral edge of the ground contact portion;
having
The connecting portion has a first inclined portion inclined from the flat surface via a first step portion toward the ground portion, a second inclined portion inclined from the first inclined portion via a second step portion toward the ground portion, a plane portion continuing from the second inclined portion and extending toward the ground portion, and a third inclined portion inclined from the plane portion via a third step portion toward the ground portion,
the first inclined portion, the second inclined portion, and the third inclined portion are inclined surfaces each having a generally arcuate shape recessed downward,
the inclined surface does not bulge downward from a horizontal plane including an outer peripheral edge of the first inclined portion, the second inclined portion, or the third inclined portion,
A radial length of the first inclined portion is greater than radial lengths of the second inclined portion and the third inclined portion,
a structure in which the radial length of the flat portion is greater than the radial length of the third inclined portion,
The height of the first inclined portion in the bottle axial direction is greater than the heights of the second inclined portion and the third inclined portion in the bottle axial direction,
a connection portion between the second inclined portion and the flat portion is recessed downward in a V-shape ,
The flat surface is formed such that a ratio D1/D2 of a diameter D1 of the flat surface to a maximum diameter D2 of a body portion connected above the bottom portion is 0.05 to 0.30.
Anti-foam bottom for plastic bottles. The flat surface is formed such that a ratio D1/D2 of a diameter D1 of the flat surface to a maximum diameter D2 of a body portion connected above the bottom portion is 0.10 to 0.25.
The foam-preventing bottom of a plastic bottle according to claim 1. The first inclined portion, the second inclined portion, and the third inclined portion are formed so that a ratio of a height of the first inclined portion, the second inclined portion, or the third inclined portion in the bottle axial direction to a total height of the plastic bottle is 0.02 to 0.1.
The foam-preventing bottom of a plastic bottle according to claim 1 or 2. The inclination angle between the extension line of the ground contact portion and a tangent to the inclined surface of the maximum curved portion of the first inclined portion, the second inclined portion, or the third inclined portion is 20 to 50 degrees.
The foam-preventing bottom of a plastic bottle according to any one of claims 1 to 3.

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