HK1213859B - Control of bubble size in a carbonated liquid - Google Patents

Description

Method of forming plastic bottles

The present application is a divisional application of an invention patent application entitled "control of bubble size in carbonated liquid", having an international application date of 2011, 9 and 29, having an international application number of PCT/US2011/053819, and having a national application number of 201180057850. X.

Technical Field

The present invention relates to a method of forming a plastic bottle.

Background

The nature of the bubbles generated within the carbonated liquid can affect the use of the carbonated liquid for a predetermined purpose. For example, the nature of the bubbles generated within a carbonated beverage can affect the perceived taste of the beverage and/or the perception that the beverage is produced in the mouth of a person drinking the beverage (the "mouthfeel" of the beverage). In many cases, it is therefore desirable to control the size of the bubbles generated within the beverage or other liquid.

Disclosure of Invention

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key or essential features of the invention or to delineate all embodiments.

Some embodiments include a container (e.g., can, bottle) for holding a carbonated beverage. Such containers may be made of plastic, metal, glass, and/or other materials and include one or more internal features to facilitate and control bubble formation. In some embodiments, these features may include an internal partition. These partitions may include various additional surface features (e.g., ridges or other linearly extending protrusions, bumps). Additional embodiments may include beverage containers wherein features to promote and/or control bubble formation are disposed on the interior bottom surface, on the interior side surface, and/or within the neck region. Still other embodiments may include a container having a bubble trap or other structure that may be secured inside the container or allowed to float in the liquid contained within the container. Still another embodiment can include a method of making and/or using any of the containers disclosed herein.

Drawings

1A 1-1I 3 are partially schematic, cross-sectional views of a beverage container, according to some embodiments, wherein the beverage container includes an interior partition.

Fig. 2 shows a bottle including a neck section having ribs formed around the entire inner circumference according to some embodiments.

Fig. 3 shows a neck of a bottle having ribs according to another embodiment.

Fig. 4A shows a bottle having an internal recess according to some embodiments.

Fig. 4B shows some examples of additional recess shapes and patterns according to some embodiments.

Fig. 5 shows a bottle having ribs extending along the length of the bottle interior according to some embodiments.

Fig. 6-11 illustrate embodiments in which a pattern of ribs is formed on the interior surface of the container.

12A 1-12E 2 illustrate beverage containers having bubble forming structures formed at the bottom of the containers, according to some embodiments.

Fig. 13a 1-13C 2 illustrate beverage containers having bubble catching structures according to some embodiments.

Fig. 14a 1-14D are beverage containers according to further embodiments.

Fig. 15A and 15B are front and cross-sectional views, respectively, of an end of an injection molding mandrel according to some embodiments.

Fig. 15C is a block diagram showing steps of forming a plastic bottle according to some embodiments.

Fig. 16 is a diagram of a blow molding stretch rod according to some embodiments.

FIG. 17A shows a cross-sectional view of a preform made with the modified core rod.

Fig. 17B shows the interior bottom of a bottle stretch blow molded from the preform of fig. 17A.

Fig. 17C shows the interior of a plastic bottle manufactured using one of the stretch rods of fig. 16.

Fig. 17D and 17E show nucleation (nucleation) caused by surface features similar to those shown in fig. 17C.

FIG. 18 is a cross-sectional view of a portion of a bottle according to another embodiment.

Fig. 19 shows the change in size and pressure of bubbles rising within the liquid.

Detailed Description

Changes in the number and type of bubbles within a carbonated beverage can significantly affect the mouthfeel of the beverage. For this and other reasons, it is desirable to control one or more characteristics of bubbles generated in the beverage. These characteristics may include the size of the bubbles produced, the shape of the bubbles, the number of bubbles produced, and the rate at which the bubbles are released and otherwise produced.

Carbonated beverages can include a liquid beverage base and dissolved gas. The beverage base may include water, syrup, condiments, and other dissolved or suspended substances. The dissolved gas may be, for example, carbon dioxide. Carbon dioxide may also be generated in situ from the aqueous carbonic acid. Upon lowering the pressure (e.g., by opening a sealed beverage container), the carbonic acid is converted to carbon dioxide gas. Because carbon dioxide is poorly water soluble, it is released as bubbles in the liquid matrix.

H₂CO₃→H₂O+CO₂

The control of the bubble characteristics may depend on a number of factors. One of these factors is the interfacial tension between the dissolved gas and the liquid matrix. Another factor is the composition of the liquid matrix. For example, the bubble size can be controlled to some extent by the addition of surfactants (surfactants, emulsifiers, etc.) to the beverage base. In particular, the champagne industry has investigated this problem and found that glycoproteins obtained from grapes can be a controlling factor in the size of small bubbles.

The bubble characteristics may also depend on gaseous nucleation, i.e., the formation of bubbles from gas dissolved in the liquid matrix of the beverage. The process of bubble formation in carbonated beverages is similar to the formation of bubbles in supersaturated solutions of gas. However, as described in more detail in example 1 below, the formation of bubbles in the supersaturated continuous liquid is not possible. Therefore, some sort of discontinuity is typically required to form the bubbles. These discontinuities may result from other ingredients dissolved or suspended in the liquid matrix, surface characteristics of the bottle or other container holding the beverage, and/or ice or other objects in the beverage, and nucleation may therefore be affected by these. Gaseous nucleation in carbonated beverages typically occurs at surfaces that are at least partially wettable by the beverage. The surface may be the surface of a beverage container and/or the surface(s) of particles or other objects suspended or floating within the beverage.

The number of bubbles that can be generated in a carbonated beverage will depend on the gas available in the liquid, e.g. as dissolved gas or as precursor, e.g. carbonic acid. The amount of gas available in a carbonated liquid is proportional to the pressure within the container holding the liquid. When sealed, the pressure inside this container is typically greater than atmospheric pressure. When the container is opened, the contained liquid is exposed to atmospheric pressure. This reduction in pressure is the driving force for the formation of bubbles and foam. The size, shape and release rate of the bubbles will depend on a number of factors including: (a) a surface on which bubbles will nucleate, (b) a viscosity of a liquid matrix of the carbonated liquid, (c) an interfacial tension between the carbonated liquid and the walls of the container, and (d) a temperature of the carbonated liquid. In some cases, it is not practical to vary factors (b) and (c) because this may require changing the chemical composition of the beverage. It may also be impractical to attempt to change the temperature (factor (d)). However, factor (a) can generally be modified without affecting the chemical composition of the beverage, and without relying on opening the beverage container under unusual temperature conditions.

The size of bubbles formed within a carbonated beverage may be affected by the availability of bubble nucleation sites on the surface of the beverage container and/or other surfaces in contact with the beverage, as well as by the surface tension of the carbonated liquid and the equilibrium pressure within the bubble for a given bubble size. With respect to bubble shape, the tendency of bubbles to acquire a spherical shape is based on the low surface energy requirement of the sphere (i.e., the sphere has the lowest surface area to volume ratio). As the bubble rises, it must overcome the hydrostatic pressure exerted by the liquid above it. During ascent, the bubbles need to push the liquid around it. This tends to change the bubble shape from spherical to slightly elliptical. When two bubbles meet, they do so on a flat surface, which again yields the smallest surface area possible for the two bubbles. As the number of bubbles in contact with each other increases, the shape of the large bubbles formed by connecting the small bubbles can be changed accordingly to create the smallest surface area possible for the volume of the connected bubbles. Thus, the shape of the bubbles may also be controlled by the number of bubbles that are in contact with each other. To a lesser extent, the shape of the bubbles may also depend on the location and depth at which nucleation occurs.

The mouthfeel of the beverage is related to the size and number of bubbles formed. The degree of foaming of the carbonated liquid is directly proportional to the number of bubbles formed. Thus, differences in the degree of foaming can result in different mouthfeel. The taste can be modified by adding very small particles to the carbonated liquid. In particular, such particles may facilitate nucleation of gas bubbles within the liquid, thereby increasing the number of gas bubbles.

The rate of release of bubbles within a carbonated beverage can be influenced by varying the pressure to which the beverage is exposed. The rate at which the released bubbles reach the surface of the beverage can be varied by creating obstacles in the path of the rising bubbles. Such obstacles may be introduced into the liquid by introducing additional plates or edges. Such plates or edges and/or other structures may be used to create an indirect path to the beverage surface.

The size, shape, release rate and number of bubbles are related to each other. These properties can be improved by improving the design of containers for holding carbonated beverages. In many cases, this involves creating more surface area to contact the beverage. This additional surface area can provide increased stability for rising bubbles and provide more control over, for example, the rate of bubble release.

Fig. 1a 1-1I 3 are partial schematic cross-sectional views of a beverage container including an internal partition according to some embodiments. The divider walls in these embodiments promote bubble formation by, for example, providing increased surface area for bubble nucleation. Furthermore, these partition walls may also cause splashing of the beverage within the container and thereby create more bubbles. In many existing containers, most of the foam is generated immediately upon opening of the container. Mechanical splashing of the beverage by the dividing wall after the container is opened may result in more bubbles being generated for a longer period of time. For example, a patron sipping a carbonated beverage will tend to move the container from an upright position to tilt the container and place the opening of the container at the patron's mouth. Due to this periodical tilting movement the partition wall will agitate the beverage. This can promote the generation of bubbles after the container is opened and help the beverage stay in a foamy state. Small appendages may be added to the dividing wall to obstruct the path of the rising bubbles and slow the collapse of the foam.

FIG. 1A1 is a cross-sectional side view of a sealed beverage container can 10a according to at least one embodiment. FIG. 1A2 is a top cross-sectional view of can 10a taken from the position shown in FIG. 1A 1. Container 10a includes a base 33a, a sidewall 31a, and a top 16 a. The interior surfaces of base 33a, sidewall 31a and top 16a define an interior volume 13a, and carbonated beverage 30 is sealed within interior volume 13 a. Outlet 11a at top 16a is closed as shown in FIG. 1A1, but is configured for opening by a consumer and is positioned on container 10a to allow beverage 30a to flow from container 10a after outlet 11a is opened. Although the embodiment shown in fig. 1a 1-1I 3 illustrates a can-shaped beverage container, in other embodiments, features similar to those shown and described in connection with fig. 1a 1-1I 3 may be included in other types of beverage containers (e.g., bottles, reusable or disposable cups, etc.).

The partition 12a extends downwardly from the top 16a of the container 10a and separates the channel 14a from the remainder of the main volume 13 a. As shown in fig. 1a1 and 1a2, baffle 12a is attached to portions of the interior surfaces of top 16a and side walls 31 a. When base 33a rests on a flat surface, partition 12a is oriented vertically.

The passage 14a is smaller than the remainder of the main volume 13a and is shaped differently from the remainder of the main volume 13 a. In order for beverage 30a in the remaining part of main volume 13a to exit through outlet 11a after opening, beverage 30 must flow around the lower end of partition 12a and into channel 14 a. Partition 12a may be formed of the same material as the material used for the sidewalls of container 10a or of some other material. In at least some embodiments, the passage 14a is the only flow path between the remainder of the main volume 13a and the outlet 11 a.

FIG. 1B1 is a cross-sectional side view of a beverage container can 10B according to another embodiment. FIG. 1B2 is a top cross-sectional view of canister 10B taken from the position shown in FIG. 1B 1. The top, side walls and base of the container 10B and the top, side walls and base of the other containers of fig. 1B 1-1I 3, the location of the elements of these containers, the openable nature of the outlet 11, and various other features of the container shown in fig. 1B 1-1I 3 are similar to the features of the container 10a shown in fig. 1a 1-1 a 2. For convenience, where similarities in features of the container 10a are readily apparent from the figures and further discussion of the described embodiments is not necessary for an explicit understanding, some of these features are discussed separately in conjunction with fig. 1B 1-1I 3. Similarly, the carbonated beverage 30 is omitted from fig. 1B1 through 1I3 for convenience. However, it should be understood that there is a beverage 30 sealed within each container having the described features.

Divider 12b is similar to divider 12a in fig. 1a1, but may not extend as far from the beverage can top as divider 12a does. In order for the beverage contained in the remainder of the main volume 13B to be discharged from the outlet 11B (shown in the closed position of figure 1B 1), the beverage must flow around the lower end of the partition 12B and into the channel 14B. Partition 12b may be formed of the same material as the sidewall for container 10b, or of some other material. The partitions 12b include a plurality of small surface features 15b to promote nucleation and/or aeration by creating turbulence through the channels 14 b. Surface features 15b may include short hair-like protrusions, small bumps, dimples or other surface depressions, and the like, as well as combinations of various types of surface features.

FIG. 1C1 is a cross-sectional side view of a beverage container can 10C according to another embodiment. FIG. 1C2 is a top cross-sectional view of can 10C taken from the position shown in FIG. 1C 1. The outlet 11c, partition 12c, main volume 13c, and surface features 15c are similar to the outlet 11B, partition 12B, main volume 13B, and surface features 15B of FIG. 1B 1. Container 10C in fig. 1C1 and 1C2 differs from container 10B in fig. 1B1 and 1B2 by having surface features 15C on both sides of channel 14C.

FIG. 1D1 is a cross-sectional side view of a beverage container can 10D according to another embodiment. FIG. 1D2 is a top cross-sectional view of can 10D taken at the location shown in FIG. 1D 1. The outlet 11d, partition 12d, main volume 13d, and passage 14d are similar to the outlet 11C, partition 12C, main volume 13C, and passage 14C of FIG. 1C 1. Container 10D of fig. 1D1 and 1D2 differs from container 10C of fig. 1C1 and 1C2 by having surface features 15D that are sloped toward outlet 11D.

FIG. 1E1 is a cross-sectional side view of a beverage container can 10E according to another embodiment. FIG. 1E2 is a top cross-sectional view of can 10E taken from the position shown in FIG. 1E 1. The tank 10e includes an outlet 11e, a partition 12e, a main volume 13e and a passage 14e similar to the features described in connection with the previous embodiments. However, in the embodiment shown in FIG. 1E1, can 10E has no additional surface features within channel 14E. In addition, the tank 10e includes a curved top 16e to vary the pressure applied to the carbonated liquid. Although fig. 1E1 shows an outward curve (i.e., top 16E is convex on its outwardly exposed surface), top 16E may alternatively be curved inward (i.e., have a concave exposed outer surface) or have other types of curvature.

FIG. 1F1 is a cross-sectional side view of a beverage container can 10F according to another embodiment. FIG. 1F2 is a top cross-sectional view of can 10F taken from the position shown in FIG. 1F 1. FIG. 1F3 is a cross-sectional side view taken from the position indicated in FIG. 1F1, with the outer wall of can 10F omitted, showing face 20F of partition 12F within channel 14F. The can 10f is similar to the can 10B of fig. 1B1, except that the partition 12f of the can 10f includes a plurality of horizontal linear projections (e.g., ribs, ridges, ribs, etc.) 15 f. The linear protrusion 15f is oriented in a direction substantially perpendicular to the direction of the main flow of liquid through the channel 14f when beverage is discharged from the remainder of the main volume 13f through the outlet 11 f. Each linear protrusion 15f may extend from the face 20f by a height of, for example, 100 nanometers (nm) to 5 millimeters (mm). Each linear protrusion 15f may be uniform in length, width, height, and other characteristics, or the individual linear protrusions 15f may differ in one or more of size or other characteristics. For convenience, fig. 1F1 to 1F3 show only 9 linear protrusions 15F. However, a greater number of linear protrusions 15f may be included, and the linear protrusions may have a closer spacing. The linear protrusions 15f may be arranged in a regular pattern as shown or may have an irregular vertical and/or horizontal distribution. Partition 12f is otherwise similar to partition 12B of FIG. 1B 1. The outlet 11f and the main volume 13f are similar to the outlet 11B and the main volume 13B of FIG. 1B 1.

Fig. 1F4 is a view of face 20ff of partition 12ff of a can similar to can 10F, and taken from a position similar to the view of fig. 1F3 that was cut away. The face 20ff is similar to the face 20f except that each linear protrusion 15f is separated by a plurality of discrete linear protrusions 15ff separated by interruptions 18 ff. Each linear protrusion 15ff may extend from the face 20ff by a height of, for example, 100nm to 5 mm. The linear protrusions 15ff may be uniform in length, width, height, and other characteristics, or each linear protrusion 15ff may be different in one or more of size or other characteristics. The interruptions 18ff may likewise be uniform or varying. The linear protrusions 15ff and interruptions 18ff may be arranged in a regular pattern as shown or may have an irregular vertical and/or horizontal distribution.

FIG. 1G1 is a cross-sectional side view of a beverage container can 10G according to another embodiment. FIG. 1G2 is a top cross-sectional view of canister 10G taken from the position shown in FIG. 1G 1. FIG. 1G3 is a side cross-sectional view taken at the location indicated in FIG. 1G1 and omitting the outer wall of can 10G, showing face 20G of partition 12G within channel 14G. Can 10g is similar to can 10F of fig. 1F1, except that face 20g includes a vertically linear protrusion 19 g. The linear protrusion 19g is oriented in a direction substantially parallel to the direction of the main liquid flow through the channel 14g when beverage is discharged from the remainder of the main volume 13g through the outlet 11 g. The number, size, shape, distribution, continuity, and other aspects of the vertical linear protrusions 19g may be varied in a manner similar to the possible variations of the horizontal linear protrusions 15F and 15ff discussed in connection with fig. 1F 1-1F 4.

FIG. 1H1 is a cross-sectional side view of a beverage container can 10H according to another embodiment. FIG. 1H2 is a top cross-sectional view of can 10H taken from the position shown in FIG. 1H 1. FIG. 1H3 is a side cross-sectional view taken at the location shown in FIG. 1H1 and omitting the outer wall of can 10H, showing face 20H of partition 12H within channel 14H. Tank 10h is similar to tank 10F of fig. 1F1 and tank 10G of fig. 1G1, except that face 20G includes both horizontal linear protrusions 15h (oriented in a direction substantially perpendicular to the direction of the main flow of liquid through channel 14 h) and vertical linear protrusions 19h (oriented in a direction substantially parallel to the direction of the main flow of liquid through channel 14 h). The number, size, shape, distribution, continuity, and other aspects of linear protrusions 15h and/or 19h may be varied in a manner similar to the possible variations discussed in connection with fig. 1F 1-1G 3.

FIG. 1I1 is a cross-sectional side view of a beverage container can 10I according to another embodiment. FIG. 1I2 is a top cross-sectional view of can 10I taken from the position shown in FIG. 1I 1. FIG. 1I3 is a side cross-sectional view taken at the location shown in FIG. 1I1 and omitting the outer wall of can 10I, showing face 20I of partition 12I within channel 14I. Tank 10I is similar to tank 10F of fig. 1F1, tank 10G of fig. 1G1, and tank 10H of fig. 1H1, except that face 20I includes a first set of diagonal linear protrusions 21I (extending from top left to bottom right in a first set of directions in fig. 1I3 that are neither perpendicular nor parallel to the direction of the main liquid flow through channel 14I) and a second set of diagonal linear protrusions 22I (extending from top right to bottom left in fig. 1I3 that are neither perpendicular nor parallel to the second set of directions of the main liquid flow through channel 14I). The number, size, shape, distribution, continuity, and other aspects of the linear protrusions 21i and/or 22i may be varied in a manner similar to the possible variations discussed in connection with fig. 1F 1-1H 3.

In other embodiments, similar to the embodiment of fig. 1C 1-1D 2, both sides of the channel may have linear protrusions such as described in connection with fig. 1F 1-1I 3. Other embodiments include further variations and combinations of the linear protrusions described in fig. 1F1 through 1I 3. Further embodiments may include curved linear protrusions, combinations of curved and linear protrusions and/or combinations of linear protrusions and features such as bumps, depressions, and the like.

The features described in connection with fig. 1a 1-1I 3 may be combined in different ways and/or with other surface features, partitions, and/or other features within the container. Generally, increased surface area for bubble nucleation will result in more bubbles, and increasing the obstruction will slow the bubble rise. In some embodiments where the container is a bottle, the channel formed by the partition of fig. 1a 1-1I 3 may be a channel of the neck of the bottle. The length, internal volume, and/or other characteristics of the neck may be varied to affect bubble formation and/or movement.

Since the physical properties of the bubbles, such as size, shape, number and bubble release rate, are interrelated, they can be adjusted together by varying the configuration of the container. Some or all of these features may be altered by configuring the vessel to change the depth at which bubble nucleation occurs. The rise of the bubbles out of the container will depend on the characteristics in the passage through which the carbonated liquid leaves the container. In some cases, beverage viscosity may be increased (e.g., by adding sweetener syrup), or tiny particles may be suspended (or otherwise designed to settle out of the beverage) in the beverage to increase bubble stability. Particle precipitation may be achieved by relying on the reduced solubility of a particular compound at reduced pressure. Thus, such compounds may be sufficiently soluble in a beverage when pressurized in a sealed container. Once the container is opened, the pressure is reduced and some of the compound will come out of solution.

In some embodiments, certain considerations are relevant when modifying a pre-existing container to create a functional surface that affects bubble size, quantity, and/or other characteristics. To achieve consistency, it may be beneficial for as much of the beverage as possible to contact or be affected by the functional surface. To control costs, it may be beneficial for the functional surface to be consistent with existing manufacturing processes (e.g., blow molding of polyethylene terephthalate (PET) preforms). Container (when modified) safety is also desirable, e.g. without creating a blocking hazard or toxic substances.

Some embodiments include beverage containers that improve the fluid dynamics of a beverage passing through the neck of a bottle or other container. Such hydrodynamic improvements may be achieved by reducing viscous drag along the inner neck surface. The reduction in viscous drag reduces the amount of gas released and the degree of "rattling" due to turbulence and drag. The end result may be improved flow and more bubbles remaining in the beverage. If taken directly from the bottle, the end result may be improved beverage flow into the mouth. It is also possible to increase the number of bubbles left in the beverage and thus improve the mouthfeel. The improved flow further reduces gas release in the mouth, allowing for increased rate of consumption and improved drinking experience.

These results are achieved in some embodiments by using "ribs," longitudinal groove micro-geometries, and/or ridges that are aligned with the direction of fluid flow. Fig. 2 shows an example of a bottle comprising a neck section 101 with ribs 102 formed around the entire inner circumference of the neck 101. Bottle 100 has a side wall 182, a top 181 of which neck 101 is a part, and a bottom (not shown). The bottle 100 may be sealed at the outlet of the neck 102 to contain a carbonated beverage in the interior volume of the bottle 100, which outlet may then be opened to allow the contained beverage to be discharged from the interior volume through the opened outlet.

In the embodiment shown in fig. 2, the ribs extend the entire length of the neck 101, but need not be so in all embodiments. As shown in the inset portion of fig. 2, the ribs may be longitudinal grooves having approximately equal height-width dimensions. However, variations in the dimensions of the ribs are equally possible. Various patterns and other features of riblets that may also be used are described, for example, in U.S. patent 5069403 and U.S. patent 4930729, both of which are incorporated herein by reference in their entirety. The cross-sectional height of the ribs (peak-to-valley gap, which may be the height of the rib ridge and/or the depth of the rib groove) may be in the range of 0.1mm to 0.5 mm. Additional embodiments include ridges having a range of sizes including, but not limited to, those described in U.S. patent 5069403 and U.S. patent 4930729. Other patterns that can be added to a container according to one or more embodiments include those described in U.S. patent 5971326 and U.S. patent 6345791, both of which are also incorporated herein by reference. Fig. 3 shows a neck 201 of a bottle according to some other embodiments, the remainder of the bottle not being shown. In the embodiment of fig. 3, improved performance may be obtained by forming the ribs 202 to have a direction 45 degrees to the main flow direction 289 of the beverage flowing from the interior of the container through the open outlet in the top end of the neck. In other embodiments, the ribs in the neck or other container portion may be disposed at different angles relative to the flow direction.

The ribs can be formed in different ways. For example, longitudinal ridges and/or grooves may be formed by applying a reverse pattern of ridges and/or grooves to the surface of the portion of the injection molded preform that forms the inner neck surface. The body of the container may be inclined to the neck to form a shallow angle, as the steepness of this angle may promote the release of gas from the beverage being poured out of the bottle. The ribs may taper to the body portion of the container and/or may extend the full length of the container.

As mentioned above, viscous drag can have an undesirable effect on the release of bubbles from carbonated beverages. As the beverage is consumed, particularly directly from a bottle or other container, the container is repeatedly tilted so that the beverage flows back and forth across the inner surface of the container. Viscous drag across the surface of the container results in the release of gas from the beverage. Over time, the gas release reduces the content of gas within the beverage, and therefore the beverage becomes monotonous and tasteless faster than if the beverage container were to remain stationary.

Some embodiments address viscous drag of an interior region of the beverage container in addition to (or instead of) the neck. At least some of these embodiments also use micro-geometric surface textures to reduce viscous drag of the container-beverage boundary layer. In one embodiment, the beverage container has an inner surface with a recess such that the recess forms a concave surface at the beverage interface. This is shown in fig. 4A. In fig. 4A, a bottle 301 has a distribution pattern of hexagonal recesses 302 on substantially all of the inner surface. The bottle 301 has a side wall, a top (with a neck) and a bottom. The bottle 301 may be sealed at the outlet of the neck to contain a carbonated beverage in the interior volume of the bottle 301, which may then be opened to allow the contained beverage to be expelled from the interior volume through the opened outlet.

For convenience, only a portion of the recess 302 is shown. As shown in the enlarged cross-sectional view of the lower portion of the bottle 301, each recess 302 may have a concave inner surface 303 and a convex outer surface 304. Fig. 4B shows an example of additional recess shapes and distribution patterns that may be used. The number of recesses may be approximately 80 to 160 (e.g., about 120) per square inch (per 6.45 square centimeters), although various other sizes and alternative configurations are possible. Examples of alternative dimensions include, but are not limited to, those described in U.S. patent 5167552, which is incorporated herein by reference. The depth of the recess may range from about 0.1mm to about 0.5mm, for example about 0.1mm to 0.15 mm, although other depths and/or depth ranges may be used.

In further embodiments, recesses similar to those shown in fig. 4A and 4B may be oriented in the opposite manner. In particular, the recess may be configured such that the recess has a convex inner surface and a concave outer surface. The recess may extend over substantially all of the container or be located in a single region of the container. For example, some embodiments may include containers with recesses located only in the shoulder regions, while other embodiments may include containers with recesses located only in the waistline region. In another embodiment, the depressions may be arranged in a plurality of discrete depression groups, one depression group being separated from the other depression group by a non-depression container wall material. Various group patterns (e.g., hexagonal soccer patterns) and/or combinations of patterns may be used.

The embodiments shown in fig. 4A and 4B, for example, may be fabricated using blow molding techniques by including a pattern corresponding to the desired pattern of recesses. If the pattern is formed by the outer surface of the container contacting the blow mold, it may be useful to change the size and/or detail of the pattern to accommodate some loss of detail and/or resolution on the inner surface of the molded container.

Instead of (or in addition to) the inner surface of the neck region, further embodiments use ribs on the inner surface of the beverage container that reduce viscous drag. Such ribs may take the form of ribs extending along the length of the container as shown in fig. 5. In particular, fig. 5 shows an exemplary embodiment of a bottle 401 having ribs 402 extending along the length of the bottle interior. Bottle 401 has a side wall, a top (with a neck) and a bottom. The bottle 401 may be sealed at the outlet of the neck to contain a carbonated beverage in the interior volume of the bottle 401, which may then be opened to allow the contained beverage to be expelled from the interior volume through the opened outlet. For simplicity, only a portion of the ribs 402 are shown. Fig. 6-11 show embodiments in which a pattern of ribs is formed on the inner container surface as a micro-geometric surface texture pattern. In each of the embodiments of fig. 6-11, the ribs may be formed on a bottle or other container having a side wall, a top (having a neck), and a bottom. A bottle or other container may be sealed at an outlet of the neck to contain a carbonated beverage in an interior volume of the container, and the outlet may be opened to allow the contained carbonated beverage to be discharged from the interior volume through the opened outlet.

In the embodiment of fig. 6-11, the ridges (peaks) of some ribs may be aligned with the grooves (valleys) of other ribs, effectively forming a series of discontinuous microgeometric surface texture patterns of individual ribs. The patterns of fig. 6-11 may resemble, to some extent, the scutellum of a shark. The microgeometry of the scutellum reduces the viscous drag of the shark through the water and allows the shark to swim at higher speeds. The embodiments of fig. 5-11 may be "bi-directional", i.e. they may reduce viscous drag in both longitudinal directions so that the same effect may be achieved regardless of whether the beverage is tipped down or tipped up back into a stable position within the beverage bottle.

Fig. 6 shows an example of a bottle 501 having a pattern of ribs 502 formed on the inner surface of the bottle. In the example of fig. 6, the rib pattern is a microgeometric pattern in which circumferential rows of ribs are offset so that the ridges of the ribs in one row are aligned with the grooves of the ridges of an adjacent row. Although only a portion of the rib pattern is shown in fig. 6, the pattern may extend over the entire inner surface of bottle 501.

Fig. 7 shows further details of the pattern of ribs 502 of the bottle 501. As can be seen in the partial circumferential cross-sectional view, the ribs have a relatively sharp-angled cross-section. As can be seen in the partial longitudinal section view, the ridge of the ribs on the inside of the bottle 501 is slightly bowed along its length. Fig. 7 also shows an alternative cross-sectional profile of another embodiment in which the rib ridges and grooves are more rounded.

Fig. 8 to 11 show further examples of alternative rib patterns. While each of fig. 8-11 shows only a small segment of the example pattern, such a pattern may extend over the entire interior surface of the bottle or other container. Fig. 8 shows a pattern similar to that of fig. 7, but in which adjacent ribs have different lengths. The upper right hand corner of fig. 8 shows a further modification in which the rib ridges and grooves are more rounded and/or in which some of the ribs have a greater height than adjacent ribs. Fig. 9 shows a pattern of a set of ribs such as shown in fig. 8. Fig. 10 shows a further variation of the rib pattern of fig. 7. There are at least three different rib heights in the pattern of fig. 10. Fig. 11 shows a pattern of a set of ribs, such as the ribs of fig. 10.

In other embodiments, the ridge and groove patterns may have additional configurations. The height of the ridges in the embodiment of fig. 5-11 may be the same as the example height provided in connection with fig. 2 (e.g., approximately 0.1 to 0.5 mm). The length of the ridges in the embodiment of fig. 5-11 may be in the range of about 0.5 to about 1.5mm, although other lengths may be used.

Embodiments such as those shown in fig. 5-11 may also be created using blow molding techniques by including a pattern corresponding to the desired pattern of ribs. If the pattern is formed by the outer surface of the container contacting the blow mold, it may be useful to vary the size and/or detail of the pattern to accommodate some loss of detail and/or resolution on the inner surface of the molded container and to account for the thickness of the material between the mold and the inner surface.

In some embodiments, a bottle, flask, or other carbonated beverage container has one or more bubble forming structures formed on a bottom surface or other surface. Because the sharp edges can encourage bubble formation and act as nucleation sites, the inclusion of these features within the container can promote bubble formation at a desired rate and at a desired size. Fig. 12a 1-12E 2 are partial schematic views of beverage containers having these bubble forming structures according to at least some embodiments. Each of fig. 12a 1-12E 2 relates to one of bottles 601 a-601E, each bottle 601 having a side wall, a top (having a neck), and a bottom. Each bottle 601 may be sealed at the outlet of the neck to contain a carbonated beverage within the internal volume of the bottle, and the outlet may be opened to allow the contained beverage to drain from the internal volume through the opened outlet. For convenience, bottle 601 (and in other figures the bottle) is shown with a flat bottom. However, bottles according to different embodiments may include bottoms that are concave when viewed from the outside, bottles having petal-like bottoms, and bottoms having other shapes.

While fig. 12a 1-12E 2 show bottles as beverage containers, other embodiments may include similar bubble forming structures in other types of containers. Further, other embodiments may include structures similar to fig. 12a 1-1E 2 but located at different locations on the bottom of the container and/or located at other locations within the container (e.g., the sidewalls). Another embodiment may include multiple bubble forming structures of the type shown in one or more of fig. 12a 1-12E 2 and/or a combination of different types of bubble forming structures.

In the embodiment of fig. 12a 1-12E 2, the bubble forming structure includes a pointed tip or other structure having sharp corners or edges. In some cases, two, three, or more sharp angles may be disposed sufficiently close to each other so that bubbles form at each sharp angle and then coalesce to form larger bubbles. This may allow the bubble size to be controlled by varying the number of cusps and their relative distances.

Fig. 12a1 shows a bottle 601 according to an embodiment. FIG. 12A2 is an enlarged cross-sectional view of bottle 601a taken from the position shown in FIG. 12A 1. The bottom 602a of bottle 601a includes projections 603a and 606a that terminate in sharp corners 604a and 605 a. In some embodiments, sharp corners 604a and 605a may alternatively be sharp edges of cratered dimples 607a formed in the raised portions of base 602 a.

Fig. 12B1 shows a bottle 601B according to another embodiment. FIG. 12B2 is an enlarged cross-sectional view of bottle 601B taken from the position shown in FIG. 12B 1. The bottom 602b of bottle 601b includes projections 603b and 606b that terminate in sharp corners 604b and 605 b. However, unlike the protrusions 603a and 606b of bottle 601b, the protrusions 603b and 606b join the bottom 602b along sharp corners 608b and 609b that also promote bubble formation. The other sharp edge is located at the bottom of the valley 607 b. In some embodiments, peaks 604b and 605b may replace the sharp edges of the crater-like valleys as the raised portions formed in bottom 602 b.

Fig. 12C1 shows a bottle 601C according to another embodiment. FIG. 12C2 is an enlarged cross-sectional view of bottle 601C taken from the position shown in FIG. 12C 1. Fig. 12C3 is a further enlarged plan view of the bottom 602C of bottle 601C taken from the position shown in fig. 12C 2. Bottle 601c includes three peaks 603 c-605 c formed on a bottom 602 c. The spires 603c to 605c may be solid and terminate in a point, may be hollow (or partially hollow) and have a sharp peripheral edge at its tip, or may have other configurations. Although the spires 603c to 605c are approximately the same height and shape, other embodiments include spires having different heights and/or different shapes. More than three spires may be included.

Fig. 12D1 shows a bottle 601D according to another embodiment. FIG. 12D2 is an enlarged cross-sectional view of bottle 601D taken from the position shown in FIG. 12D 1. FIG. 12D3 is a further enlarged plan view of the bottom 602D of bottle 601D taken from the position shown in FIG. 12D 2. Bottle 601d is similar to bottle 601c except that the bottom 602d of bottle 601d includes three taller peaks 603d and nine shorter peaks 604 d. The peaks 603d and 604d may be solid and terminate in a sharp point, may be hollow (or partially hollow) and have a sharp peripheral edge at their tip, or may have other configurations. Other embodiments may include additional (or fewer) peaks, may include peaks having heights different from peaks 603d and 604d, may include peaks having different shapes, may include combinations of different peak heights and shapes.

Such as those of fig. 12C1 through 12D3, as well as peaks, bumps, protrusions, and/or other surface features according to other embodiments, may be scored, sandblasted, or otherwise scratched or treated to create a roughened surface to increase nucleation points. The peaks, bumps, protrusions, and/or other surface features, whether roughened or not, may be treated with a silicone spray or another agent to alter the wetting characteristics of the surface and facilitate more rapid bubble release.

Fig. 12E1 shows a bottle 601E according to another embodiment. FIG. 12E2 is an enlarged cross-sectional view of bottle 601E taken from the position shown in FIG. 12E 1. Bottle 601e includes a protrusion 603e extending from a base 602 e. Protrusion 603e includes three sharp corners 604e formed at the ends of protrusion 603 e. Other embodiments may include additional protrusions and/or protrusions having additional (or fewer) sharp corners.

The number, size, shape, distribution, and other aspects of the spires, lobes, protrusions, and/or other surface features may vary in numerous ways other than those explicitly described herein.

Some embodiments include a bubble trapping structure. Fig. 13a1 shows a bottle 701a according to such an embodiment. FIG. 13A2 is an enlarged cross-sectional view of bottle 701a taken from the position shown in FIG. 13A 1. Each of fig. 13a 1-13C 2 relates to one of bottles 701a-701C, each bottle 701 having a side wall, a top (having a neck) and a bottom. Each bottle 701 may be sealed at the outlet of the neck to contain a carbonated beverage in the interior volume of the bottle, which may then be opened to allow beverage to drain from the interior volume through the opened outlet. Bottle 701a includes a dome-shaped bubble catching structure 703a affixed to a base 702 a. For convenience, tabs or other structures connecting the bubble catching structure 703a to the base 702a are not shown. The bubble catching structure 703a forms a volume 704a that is partially separated from the main volume 707 a. Except for the area around the edge of bubble catching structure 703a and the orifice 705a of bubble catching structure 703a, liquid (and bubbles) cannot pass between areas 704a and 707 a. As also shown in fig. 13a2, orifice 705a is disposed at or near the uppermost portion of the dome of bubble catching structure 703 a. When bottle 701a is in an upright configuration, bubbles trapped under structure 703a can only escape into main volume 707a through orifice 705a, but liquid within bottle 701a can readily reach region 704a through an opening at the edge of structure 703 a.

The upper surface 708a of structure 703a is smooth to minimize bubble formation. However, the underside 706a and/or the bottom 702a of structure 703a includes a plurality of scratches, sharp edges, or the like to encourage bubble formation. Bubbles formed under structure 703a will coalesce into larger bubbles before (or during) escaping from orifice 705a to region 707 a.

Fig. 13B1 shows a bottle 701B according to another embodiment. FIG. 13B2 is an enlarged cross-sectional view of bottle 701B taken from the position shown in FIG. 13B 1. Bottle 701b is similar to bottle 701a except that dome-shaped bubble catching structure 703b is not secured to bottom 702 b. Instead, structure 703b may move up and down within volume 707 b. Therefore, the area 704b has an unfixed size. The upper surface 708b is smooth. The bottom surface 706b (and/or the bottom 702b) includes scratches, sharp edges, and/or other surface features to promote bubble formation. Bubbles formed under structure 703b nucleate and escape through orifice 705b, with outlet 705b being disposed at or near the uppermost portion of the dome of bubble catching structure 703 b. In some embodiments, forming a sufficiently large bubble under structure 703b may allow structure 703b to move up and down in a periodic manner within main volume 707 b. In some embodiments, structure 703b may be stabilized by lowering its center of gravity (e.g., attaching weights underneath) and/or by having the sides of structure 703b conform relatively closely to the inner walls of bottle 701 b. In the embodiment of fig. 13a 1-13B 2, the size of the bubbles entering the main volume of the bottle can be controlled by the diameter of the orifice.

Fig. 13C1 shows a bottle 701C according to another embodiment. FIG. 13C2 is an enlarged cross-sectional view of bottle 701C taken from the position shown in FIG. 13C 1. Bottle 701c includes structure 703c, which is free to move within main volume 707 c. One or both surfaces of structure 703c may have scratches, sharp edges, and/or other surface features to promote bubble growth. Structure 703c lacks an aperture and is allowed to rotate freely. Bubbles formed on the underside of structure 703c escape upward as structure 703c tilts upward. Structure 703c may be symmetric or asymmetric, may have the shape shown or may have other shapes. In some embodiments, structure 703c has a width (W) that is greater than width (A) of the neck opening of bottle 701c_w) And a length (L) less than the width (B) of the interior of bottle 701c_w). More than one structure 703c may be included in bottle 701 c.

Although fig. 13a 1-13C 2 show embodiments in which the beverage container is a bottle, structures such as the embodiment shown in fig. 13a 1-13C 2 can be applied to other embodiments in which the container is a can, a reusable or disposable cup, or the like.

In some embodiments, the shape of the beverage container may be configured to increase the inner surface area and/or increase the number of internal corners, edges, or other surface features that may help promote nucleation. For example, the container may be formed with a through hole, a recess, a notch, or the like. Examples of such bottles are shown in fig. 14a 1-14D. Each bottle of fig. 14a 1-14D includes a side wall, a top (having a neck), and a bottom. Each bottle may be sealed at the outlet of the neck to contain a carbonated beverage in the interior volume of the bottle, which may then be opened to allow the contained beverage to drain from the opened outlet. As an additional advantage, the container structures shown, for example, in fig. 14a 1-14D may also be used to create a distinctive appearance for product marketing or other purposes. Fig. 14a1 shows a bottle 800 having two sealed through-holes 801, 802 disposed within the bottle. Fig. 14a2 is a cross-sectional view of bottle 800 taken from the position shown in fig. 14a 1. As shown in fig. 14a2, each hole 801 and 802 provides an external passageway through the body of bottle 800 without exposing the interior of the bottle. Fig. 14B shows a bottle 810 with a star-shaped sealed through hole 811. Fig. 14C is a longitudinal cross-sectional view of a bottle 815 having a plurality of notches 816 projecting inwardly toward the interior of the bottle. Fig. 14D is a longitudinal cross-sectional view of a bottle 825 with a pair of inwardly projecting notches. A protrusion 827 extends from an inner surface of the notch 826. In yet another embodiment, the entire outer profile of the bottle may be custom shaped (e.g., long serpentine, star-shaped) to increase the inner surface area and/or internal nucleation features.

Beverage containers according to various embodiments may be formed using a variety of techniques. For example, nucleation sites may be formed on the interior region of a plastic beverage bottle during the blow molding process. As described above, molds used to form plastic bottles may include protrusions, depressions, or other features that create external features on the outer surface of the bottle. These external features would then have corresponding features on the inner surface of the bottle (e.g., a dimple created on the outside of the bottle would create a bump on the inside of the bottle).

As another example, internal surface features may be formed on plastic bottle preforms using a mandrel having surface features corresponding to desired surface features. When the preform is stretched and blown, the internal surface features of the preform will become the internal surface features of the plastic bottle. FIG. 15A is a front view of a mandrel 901 according to one embodiment. Fig. 15B is a sectional view of the tip of the mandrel 901 taken from the position shown in fig. 15A. The bar 901 includes a plurality of superfine channels 902 formed in a curved front surface 903 of the bar 901. In operation, the core rod 901 is placed in the mold cavity. Molten PTE or other material is then injected into the space between the rod 901 and the cavity wall to create a preform that will be subsequently used to blow mold a beverage container. During injection molding, the molten material flows into the channel 901 to produce a pointed protrusion on the portion of the preform corresponding to the inner bottom surface of the resulting plastic bottle. The dimensions (diameter and/or depth) of each channel 902 may vary in different embodiments, and not all channels need be the same size. The number and distribution of channels may likewise be varied in different embodiments. In some embodiments, one or more channels at the forwardmost tip of the end 903 may be omitted so that the resulting preform will have an area without protrusions to better accommodate the stretch rod in blow molding. In another embodiment, a push rod used with a preform produced from core rod 901 may have a concave cup-shaped end that fits over a protrusion in the preform. The concave region of the end portion receives the protrusions during the stretch blow molding process without damaging them. The ring at the end of the pusher pushes against a portion of the preform surface surrounding the protrusion in the preform.

Fig. 17A is a diagram showing a cross section of a preform made from a core rod similar to core rod 901 of fig. 15A and 15B. However, the mandrel used to make the preform of fig. 17A has only nine channels. These channels are wider than the channel 902 of the mandrel 901 and are conical. FIG. 17B is a drawing of the interior bottom of a bottle stretch blow molded from the preform of FIG. 17A.

The internal surface features within the container may alternatively (or simultaneously) be created by modifying the stretch rod used to push against the bottom surface of the preform in blow molding. Such stretch rods may be used to create spikes or other protrusions, surface microprotrusions, inclusions or other types of surface features on the interior base area of blow molded bottles. The stretch rod may alternatively or additionally be used to create a surface texture to the interior base region of the bottle. In addition to forming nucleation sites for controlling bubble formation, texture and surface features formed inside or outside the bottle may be used to introduce decorative features for aesthetic purposes.

Fig. 15C is a block diagram of the steps of forming a plastic bottle having one or more internal surface features using a stretch rod with a modified tip. At step 991, a stretch rod having a modified tip is inserted into a fully heated plastic preform. The neck of the preform is fixed with respect to the axis of movement of the stretching rod (i.e. will also correspond to the longitudinal axis of the bottle to be formed). In step 992, the stretch rod is pushed against the inner bottom surface of the preform to force the heated plastic of the preform into the cavity of the modified tip. In step 993, gas (e.g., air) is blown into the stretched preform, and the preform axially expands against the inner walls of the blow mold. This results in a bottle having a bottom surface feature that corresponds to the surface feature of the stretch rod tip. Different types of stem tips may be applied to form various types of internal surface features in blow-molded containers.

For example, fig. 16 is a diagram illustrating the ends of the four stretch rods 921 and 924 according to some embodiments. The stem 921 has seven conical depressions 929 formed in its end surface 925. Each recess 929 is approximately 0.05 inches deep. The lever 922 has seven conical recesses 929 formed in its end surface 926. Each recess 930 is approximately 0.1 inches deep. The rods 923 and 924 have a plurality of irregularly shaped depressions formed in the respective end surfaces 927 and 928.

The test bottles were blown through each end rod shown in fig. 16 using green plastic preforms. Process adjustments are made to slow the molding machine to allow the temperature to equilibrate more thoroughly within the preform and to allow the details to be more fully formed. The stretch rod is also adjusted to press the preform material more tightly than in conventional blow molding to press the preform material to the bottom of the stretch rod. It is desirable to have a flat surface in the base mold that corresponds to the location against which the rod end is pressed.

Fig. 17C is a view of the interior of a bottle blow molded by the stem 921. In some cases, instead of a modified pushrod similar to pushrod 922, a high aspect ratio protrusion (such as that shown in fig. 17B) may be more easily produced using a modified mandrel (such as that described in connection with fig. 17A).

All features of the bottle blow molded by the rods 921 to 924 serve as nucleation points. Due to the respective surface features, the bubble release rate is controlled according to the bubble growth rate. Fig. 17D and 17E show nucleation resulting from surface features similar to those shown in fig. 17C.

In other embodiments, nucleation sites may be formed by other methods. Fig. 18 is a cross-sectional view of a portion of a bottle 1001 according to one such embodiment. The bottle 1001 includes a bottom 1003 and a sidewall 1002 (only a portion of the sidewall 1002 is shown), and has a top (not shown) that includes a neck (not shown). The bottle 1001 can be sealed at the outlet of the neck to contain a carbonated beverage in the interior volume of the bottle 1001, which can be opened to allow the contained beverage to drain from the inner container through the opened outlet.

The bottom 1003, side walls 1002, and top of the bottle 1001 are formed of a first material (e.g., PET or other plastic). A plurality of discrete elements 1004 are embedded in the inner surface of the bottom 1003 and/or the inner surface of the lower portion of the sidewall 1002. The element 1004 is partially exposed to the beverage contained in the bottle 1001. Although not shown in the cross-sectional view of fig. 18, the elements 1004 may be distributed around the entire circumference of the bottle 1001 across the entire surface of the bottom 1003 and in the lower portion of the sidewall 1002. Each element 1004 is formed of a second material that may be different from the first material. For example, the discrete elements 1004 may include embedded particles of silica (e.g., sand sized), embedded particles of an inorganic material, embedded particles of a plastic different from the first material plastic, and the like. Other materials that may be embedded or otherwise attached to the interior surface of the bottle or otherwise disposed within the bottle may include wood fibers, coffee filter material, food grade insoluble fibers, for capillary properties and for other materials to be adhered to the base of the bottlecellulose/PET fibers optimized for bubble structure control, fibrous networks having bubbles trapped therein to act as nucleation sites for carbon dioxide bubbles, floating on the surface of the beverage and having a size slightly less than O₂A semi-permeable membrane having a pore size of molecular size and activated carbon inclusions.

In some embodiments, the sidewall surface portion with the embedded element 1004 may extend further up within the bottle (e.g., approximately half the height of the bottle). In yet another embodiment, only the inner bottom surface may have embedded elements. In yet another embodiment, only the interior sidewall surface may have embedded elements. The embedded elements may be arranged in groups separated by regions without embedded elements.

In yet another embodiment, the bottom or other interior region may be roughened by grit blasting, by cryogenic grinding, or the like. In another embodiment, the prior art for producing bottles with a layer of foamed plastic may be modified to produce bottles with one or more areas of foamed plastic inside the bottle. Techniques for producing bottles with foamed plastic layers are described, for example, in U.S. patent 7,588,810, in U.S. patent application publication No. 20050181161, in U.S. patent application publication No. 20070218231, in U.S. patent application publication No. 20080251487, in U.S. patent application publication No. 20090297748, and in international patent application publication No. WO2008/112024, each of which is incorporated by reference in its entirety.

With respect to beverage containers formed by any of a variety of methods, numerous factors may be considered when attempting to increase foaming. In general, a greater number of nucleation points results in more bubble formation. With respect to the geometry of the nucleation sites, high surface energy is desirable. This typically corresponds to a high aspect ratio (i.e., a high aspect ratio). Highly fine structures (e.g. oblate shapes similar to cereal-like pasta, needles) may be applied here. The density of nucleation sites in a given area is also relevant. Larger bubbles may form from regions with increased nucleation point density, and larger bubbles may be released and rise faster. The location of the nucleation points may also be relevant. The nucleation sites may sometimes be more useful at the bottom of the container, since the potential energy associated with surface tension may be higher at the bottom than at the neck of the bottle.

A greater number of spikes (or other types of protrusions) can result in more bubble release than fewer spikes (or other types of protrusions). Greater spacing between the spikes/protrusions can also increase the number of bubbles released and/or decrease the size of bubbles released. The inverse relationship to the number and spacing of the spikes/projections is equally applicable.

Example 1:

the pressure inside the bubble is expressed by equation 1:

P_{air bubble}＝P_{Atmosphere (es)}+P_{Carbonic acid liquid}+2Y/R (equation 1)

Wherein:

surface tension of a carbonated liquid

R is the radius of the hole

P_{Carbonic acid liquid}Pressure exerted by liquid above the bubble

P_{Atmosphere (es)}Atmospheric pressure

Fig. 19 shows the change in size and pressure of bubbles rising inside the liquid. As can be derived from equation 1, the equilibrium pressure within the bubble is inversely proportional to the size of the bubble. The pressure within the bubble is also dependent on the surface tension of the carbonated liquid. As the bubble rises, the pressure P_{Carbonic acid liquid}And (4) descending. Since the equilibrium pressure inside the bubble depends on the pressure exerted by the carbonated liquid above the bubble, P_{Air bubble}And also decreases. Such a reduction in pressure is accommodated by an increase in the size of the bubbles. In addition to this, as the bubbles rise, gas from the carbonated liquid surrounding the bubbles also diffuses into the bubbles due to the pressure difference. Described below is a mathematical explanation of why very small bubbles will not form without some surface bubble nucleation.

Air bubbleWill tend to be spherical because the surface/volume ratio of this shape is minimal, but the bubbles within the liquid must push the surrounding liquid as they rise, and thus, in practice, have a slightly distorted shape²To create this large surface in the liquid, the work required to overcome the surface tension of the liquid is equal to 4 П R²Y. the amount of gas within the bubble will be (4/3) П R³The free energy release from a bubble will be (4/3) П R³ρ F. as long as 4/3 П R³ρF>4ПR²Y, i.e. as long as R ρ F>3Y, spontaneous gas evolution is possible. From this relationship it is clear that the term R ρ F will be less than 3Y for sufficiently small values of R, regardless of the value of (correlated) ρ, F, Y. Also, because the bubbles must be small at nucleation prior to bubble growth, very tiny bubbles cannot form at the same time.

Given that the supersaturated carbonated liquid will equilibrate with the gas at pressure P, it will tend to diffuse the gas to a location where the pressure is less than P. In the case of random nucleation, there is a statistical probability that bubbles with small and large (R) will occur simultaneously, but they will not persist. Controlling whether these nuclei are sufficiently thermodynamically stable for growth is the Gibbs free energy volume and surface area energy balance. Above the critical free energy, nuclei can grow. From equation 1, it is apparent that the pressure within the bubble is greater than the surrounding liquid 2Y/R (assuming the pressure exerted by the carbonated liquid is negligible). Thus, the bubble will grow only if the term 2Y/R is less than the surrounding pressure P. Since R needs to be small enough at nucleation, the above condition can only be achieved by an improbably large value of P. For a given container volume, providing a usable surface for nucleation of bubbles within the carbonated liquid may facilitate foaming.

Overview

The foregoing description of one or more embodiments of the invention has been presented for purposes of illustration and discussion. The foregoing description is not intended to be exhaustive or to limit the embodiments to the precise form explicitly described herein. Modifications and variations are possible in light of the above teachings or may be acquired from practice of various embodiments. The embodiments discussed herein were chosen and described in order to explain the principles and the nature of various embodiments and its practical application to enable one skilled in the art to make and use these and other embodiments with various modifications as are suited to the particular use contemplated. Substitutions of any and all features from the above-described embodiments are also within the scope of the invention.

Claims (14)

1. A method of forming a plastic bottle comprising:

placing a mandrel in a mold cavity, wherein the mandrel has a plurality of channels formed in a front surface of the mandrel;

injecting molten plastic into the space between the core rod and the wall of the mold cavity to produce a preform having a pointed protrusion; and

blow molding the preform to form a plastic bottle having a pointed protrusion on an inner bottom surface of the plastic bottle;

wherein the blow molding operation comprises stretch blow molding with a pushrod having a concave cupped end that fits over the pointed protrusion in the preform.

2. The method of claim 1, wherein not all channels have the same dimensions.

3. The method of claim 1, wherein the ring at the end of the pusher pushes against a portion of the surface of the preform surrounding the pointed protrusion in the preform.

4. The method of claim 1, wherein the channel is conical.

5. The method of claim 1, wherein the pointed protrusions are conical.

6. The method of claim 1, wherein the molten plastic comprises molten polyethylene terephthalate (PET).

7. A method of forming a plastic bottle comprising:

inserting a stretch rod into a heated plastic preform having a neck, wherein the neck is fixed with respect to an axis of motion of the stretch rod, and the stretch rod comprises a tip having a cavity formed therein, the cavity having a shape corresponding to a pointed extension;

pushing a tip of a stretch rod against an inner bottom region of the preform to force heated plastic of the preform into the cavity; and

blowing gas into the stretched preform to produce a plastic bottle having a pointed extension formed on an inner bottom surface thereof.

8. The method of claim 7, further comprising roughening a surface of the pointed extension.

9. The method of claim 8, wherein the surface of the pointed extensions is roughened by scoring, sandblasting, or scratching.

10. The method of claim 7, further comprising treating the pointed extensions with silicone.

11. The method of claim 7 wherein the cavity is a conical depression formed in the stretch rod tip and the pointed extension has a conical shape.

12. The method of claim 7, wherein the pointed extensions are spikes.

13. The method of claim 7, wherein the plastic preform is a green plastic preform.

14. The method of claim 7, wherein the heated plastic preform comprises a heated polyethylene terephthalate (PET) preform.