Container and method for blowmolding a base in a partial vacuum pressure reduction setup

[0001] The invention generally relates to a container blow molding method, and more particularly to a container blow molding method with a base having sufficient rigidity to withstand the forces acting during inversion of the base wall.

Related Art [0002] One method of making containers is a process known as stretch blow molding (blow molding and additional stretching of the preformed container, so-called preforms). In this process, the preformed blow preform, or preform, is made of a thermoplastic material, generally by injection molding. This preform usually has a threaded end that becomes the thread of the container. During stretch blowing, the preform is sandwiched between two open blow mold halves. The blow mold halves close around the preform and cooperate to provide a seat in which the preform is blown to form the container. After closing the mold, gas is injected into the preform, causing it to stretch and take the shape of the mold after the plastic has contacted the mold. After forming, the mold halves open to release the blown container.

[0003] One of the problems associated with stretch blowing is that stretching of the plastic material can affect the technical characteristics of the container in certain areas. While stretching plastic material may not cause

76P31023PL00

As a problem for most container sections, this particularly affects the ability of the plastic material to form around the deep protrusion in the mold. In some applications, when making the container, you may need a deep projection in a specific part of the container, most often in the base of the container. As the plastic comes into contact with the deep protrusion of the mold, the plastic must stretch and flow around the protrusion into the recess. However, the plastic material is less able to flow and stretch around the projection due to contact friction with the mold surface. Insufficient distribution of the material in an area, such as a base, may affect the ability of this area to hold its shape around the projection during hot filling, the strength of the area, or the container's ability to stand on a flat surface.

A container for removing a vacuum, the base of which includes a reversible part, is disclosed, for example, in International

Patent Application WO2004 / 028910. A method of forming the bottom of a container by stretch blow molding is disclosed, for example, in European Patent Application No. EP1063076.

[0004] The lack of clarity in the base, resulting from the inability of the plastic to properly form in the deep projection, is a particular problem when one or more reversible walls are in the base. If the reversible walls or the surrounding areas of the base are not rigid enough, the inversion of the walls can deform the base, which can create problems in terms of the ability of the container to stand stable on a flat surface and can affect the appearance of the container.

[0005] What is needed is an improved method

76P31023PL00

EP 1 996 382 B1 forming a container base that eliminates the disadvantages of conventional solutions.

BRIEF DESCRIPTION OF THE INVENTION [0006] To accomplish this, the invention has the features as defined in the claims.

[0007] Further advantages as well as the structure and operation of exemplary embodiments will be apparent after analyzing the description, drawings and examples.

BRIEF DESCRIPTION OF THE DRAWINGS [0008] The above and other features and advantages of the invention will be apparent from the following, more detailed description of exemplary embodiments of the invention, illustrated in the accompanying drawings, in which similar reference numbers may generally indicate identical, functionally similar and / or structurally similar elements.

[0009] FIG. 1A illustrates an exemplary embodiment of the first step of forming a container base according to the present invention;

[0010] FIG. 1B is a perspective view of the exemplary base of the container of Fig. 1A according to the present invention;

[0011] FIG. 2A illustrates an example of forming a container base according to the invention;

second step of the present [0012] FIG. 2B is a perspective view of the exemplary base of the container of Fig. 2A in accordance with the present invention;

[0013] FIG. 3A illustrates an exemplary embodiment of the third step of forming a container base according to the present invention;

[0014] FIG. 3B is a perspective view

76P31023PL00

An exemplary base of the container of Fig. 3A, according to the present invention; and [0015] FIG. 4 is an enlarged illustration of an exemplary mold for forming a container base.

[0016] Further objects and advantages, as well as the structure and operation of exemplary embodiments, will become apparent after analyzing the description, drawings and examples.

DETAILED DESCRIPTION OF THE INVENTION [0017] Exemplary embodiments of the invention are discussed in detail below. In the description of exemplary embodiments, specific terminology is used for clarity. However, the invention is not intended to be limited to the specific terminology selected in this way. While specific embodiments have been discussed, it should be understood that this has been done for illustrative purposes only. One skilled in the art will recognize that other components and configurations may be used without departing from the spirit and scope of the invention. All references cited herein are incorporated by reference as if each of them is incorporated separately.

[0018] Exemplary embodiments of the present invention may generally relate to a container, a method for making the container and the container base taking into account the stiffness and vacuum requirements imposed on the container during the hot filling process. In an exemplary embodiment, the base of the container may include a plurality of reversible walls and hinges. Reversing the reversible walls can be used to partially reduce the vacuum acting on the container during the hot filling process. Initially, the reversible walls can be formed into a container mold so that they protrude away from the interior of the container. In the form of

76P31023PL00

According to an exemplary embodiment of the present invention, the container has eliminated most of the deep protrusions in the mold and replaced the deep protrusions with one or more recesses that form reversible walls. The presence in the form of a cavity instead of a deep protrusion allows the plastic to flow into the cavity in order to better mold all mold surfaces in the base area, thereby increasing the orientation of the plastic in the cavity. By stretching the plastic into the cavity, the possibility of the base setting during the hot filling process can be reduced. After blow molding the reversible walls so that they protrude away from the interior of the container, the reversible walls can be rotated around the hinges in the base, in one or more stages, to form the final shape of the container.

[0019] Figs. 1A-B illustrate an exemplary embodiment of a first stage container having the shape of a stretch blow molded container according to the present invention. Figs. 2A-B illustrate an exemplary embodiment of the second stage container after inverting the first wall of the present invention. FIG. 3A-B show an exemplary embodiment of the third step of the container after inverting the second wall to partially reduce the vacuum applied during the hot filling process of the container according to the present invention. FIG. 4 shows a mold for forming an exemplary container according to the invention. The mold has left side 10, right side 20 and base 30 that can be brought together around the preform to form the mold, or separated to release the formed container.

[0020] Exemplary embodiments will be initially discussed with reference to Figs. 1A-B. According to an exemplary embodiment of the present invention, the container 100 is

76P31023PL00

EP 1 996 382 B1 blow-molded to the shape shown in Figs. 1A-B. FIG. 1A is a side view of an exemplary container 100, and FIG. 1B is a perspective view of the base of an exemplary container 100 according to an exemplary embodiment of the present invention. As shown, the container 100 includes an upper portion 102, a neck 104, a container body 106 and a base 108. The top portion 102 of the container 100 is generally any structure having an opening for the interior of the container 100 and is adapted to receive a closure (not shown). The closure may be any device used to form a substantially airtight seal for the hot-filled product inside the container 100, and thereby substantially preventing air from entering the container 100 through the top portion 102. In one exemplary embodiment, the top portion 102 includes a thread 112 that is adapted to engage with a closure that is a screw cap. The cap may be screwed onto the thread 112 of the upper part 102 to form a seal with the container 100. In an alternative embodiment, a sealing plug may be provided in the upper part 102 to seal the container 100. Other closures or seals may be used as known to those skilled in the art.

[0021] The neck 104 of the container 100 extends from the upper portion of the container body 106 to the lower portion of the upper portion 102. Generally, the neck 104 narrows as it extends from the container body 106 to the lower portion of the upper portion 102. The neck 104 may have any desired shape or it may not be in the container 100. The neck 104 may include patterns, shapes and other geometric elements, or alternatively it may be substantially smooth. In the embodiment shown, the width of the lower neck portion 104 corresponds to the width of the upper body portion 106 of the container i

76P31023PL00

EP 1 996 382 B1 tapers, curving inward as neck 104 approaches upper portion 102. Neck 104 curves outward before reaching upper portion 102, and then curves inward when neck 104 reaches upper portion 102. The neck 104 may have different shapes and contain different designs, as known to those skilled in the art.

[0022] The body 106 of the container 100 extends from the base 108 to the neck 104 and defines the interior of the container 100. The body

106 the container is located below the neck 104. In an alternative embodiment, if the neck 104 is not in the container 100, the container body 106 extends to the upper portion 102. The container body 106 may have any asymmetrical or symmetrical shape such as, but not limited to, cylindrical, square, rectangular, or with different geometry. Optionally, the container body 106 of the container 100 may include a patterned support structure or vacuum panels. The patterned support structure and vacuum panels can help to ensure the structural integrity of the container 100.

[0023] In the embodiment shown, the container body 106 has a cylindrical shape and has ribs 114 and a plurality of vacuum panels 116A-B. Ribs 114 may be a series of recessed sections alternating with non-recessed sections on the container body 106. Vacuum panel 116A can be configured to form a hand grip area, and vacuum panel 116B can be substantially flat depressed sections with a much larger depressed area than ribs 114. Alternatively, the vacuum panel 116B may include a hand grip, and the vacuum panel 116A may be a substantially flat depressed section. Other types of vacuum panel and / or combinations thereof are known in the art.

The container according to the invention may also contain others

76P31023PL00

EP 1 996 382 B1 types of vacuum panels. Ribs 114 may include other types and shapes, and both ribs 114 and vacuum panels 116A-B may be located at other locations on the container body 106, as is known to those skilled in the art. The ribs 114 and vacuum panels 116A-B may also not be in the container body 106, or may be located elsewhere on the container 100.

[0024] The base 108 may include a convex annular wall 132, a support surface 118, a first hinge

142, first wall 120, second hinge 122, second wall 124, third hinge 144, and section 126. Support surface 118 is the contact surface of the container 100 that can contact the flat surface when the base

108 it is in the third stage, discussed below, and upright on a flat surface. The container 100 is upright on a flat surface when a substantial portion of the support surface 118 is in contact with the flat surface and the flat surface is under the container 100. The support surface 118 may have other asymmetrical or symmetrical geometries as known to those skilled in the art. The support surface 118 is between the convex annular wall 132 and the first hinge 142. The convex annular wall 132 is adjacent the body 106 of the container 100. The convex annular wall 132 may extend completely around the support surface 118, or alternatively may include a notch 134, such like a sprue on the label. As is known in the art, a label head can be used to orient the container 100 to apply the label at a desired location on the container 100.

[0025] Initially, when the container 100 is stretch-blow molded, the first wall 120 and the second

76P31023PL00

The wall 124 is formed so that it extends from the interior of the container 100 along the longitudinal axis 150 of the container 100. The first wall 120 of the container 100 is between the first hinge 142 and the second hinge 122. In the embodiment shown, the first wall 120 has generally, the outer wall shape of a truncated cone and is concentric with the longitudinal axis 150. The first wall 120 may have the shape of a truncated cone. In addition, the first wall 120 may have other asymmetrical or symmetrical shapes, as known to those skilled in the art. Similarly, the first hinge 142 is concentric with the longitudinal axis 150 and may also be formed into other asymmetrical or symmetrical shapes. The first wall 120 slopes away from the first hinge

142 to the second hinge 122 away from the interior of the container 100. The slope of the first wall 120 may be curved or linear, or it may be a combination of curved and linear sections. The first wall 120 may include folds 128 that are adapted to bend to allow the first wall 120 to rotate about the first hinge 142. Alternatively, if the angle between the first wall 120 and the horizontal plane in which the supporting surface 118 lies is sufficiently shallow, then the first wall 120 need not contain any folds, as described in US Patent No. 6,942,116, published September 13, 2005, the content of which is incorporated in its entirety by reference.

[0026] A first hinge 142 is formed between the supporting surface 118 and the first wall 120.

The first hinge 142 is formed in a plastic material such that when an upward axial force is applied to the second wall 124, the first hinge 142 essentially maintains its original shape without wrinkling or deformation, thereby allowing the first wall 120 to pivot around

76P31023PL00

EP 1 996 382 B1 to the first hinge 142. The first hinge 142 is depicted as a circular ring which is offset from the supporting surface 118. However, the first hinge 142 may have other asymmetrical or symmetrical shapes as known to those skilled in the art.

[0027] The second hinge 122 is located at the intersection of the first wall 120 and the second wall 124. The second hinge 122 is depicted as a circular ring which is offset from the supporting surface 118. However, the second hinge 122 may have other asymmetrical or symmetrical shapes as is known specialists in this field of technology. The second hinge 122 is formed in a plastic material such that when an upward axial force acts on the second wall 124, the second hinge 122 substantially maintains its original shape without wrinkling or deformation, thereby allowing the second wall 124 to pivot around the second hinge 122 In one embodiment, the angle of the first wall 120 and the second wall 124 relative to the horizontal plane in which the support surface 118 lies may be about 25 ° -50 °.

[0028] The second wall 124 is positioned between the second hinge 122 and the third hinge 144. The second wall 124 is adapted to rotate around the second hinge 122.

As shown, the second wall 124 is frustoconical outer wall and concentric with the longitudinal axis 150. The second wall 124 may be frustoconical. Other shapes may be used for the second wall 124 and the second hinge 122, as known to those skilled in the art. After the initial blow molding, the second wall 124 slopes in a substantially linear direction from the second hinge 122 towards the third hinge 144. This tilt direction is essentially the direction from inside the container 100 relative to the axis

76P31023PL00

EP 1 996 382 B1 150. The initial tilt direction of the second wall 124 may be the same direction as the initial tilt direction of the first wall 120, as shown in Figs. 1A-B. However, the initial slope directions of the first wall 120 and the second wall 124 may be different, which is obvious to those skilled in the art. The second wall 124 in the embodiment shown also includes folds 136 that facilitate the rotation of the second wall 124 around the second hinge 122. The folds 136 are adapted to bend when the position of the second wall 124 is moved to facilitate rotation around the second hinge 122.

[0029] The third hinge 144 is at the intersection of the second wall 124 and section 126. The section 126 is adapted to pivot around the third hinge 144 while the second wall 124 rotates around the second hinge 122. The third hinge 144 is depicted as a circular ring which is displaced from the supporting surface 118. However, the third hinge 144 may have other asymmetrical or symmetrical shapes, as known to those skilled in the art.

[0030] The section 126 is centrally located inside the second wall 124, and may be concave, convex or flat relative to the interior of the container 100. The section 126 is adapted to receive a mechanical device that changes the position of the second wall 124 around the second hinge 122. This the mechanical device can force the section 126 to change the position of the second wall 124. Alternatively, an air or pneumatic cylinder (not shown) may be used for forced air supply to invert the second wall 124. To invert the second wall 124, the base 108 may be operated with other types of forces, as known to those skilled in the art.

76P31023PL00

EP 1 996 382 B1 [0031] The container 100 is blow molded into the shape shown in Figs. 1A-B to increase the rigidity of the base 108. The container 100 is molded to this shape to ensure that all base areas 108 are properly formed and are sufficiently defined. The advantage of forming the container 100 in the first stage is that the rigidity of the base 108 is increased by allowing further orientation of the plastic material in the base 108 (see Figs. 1A-B), compared to the initial forming of the container into the shape shown in the second stage (see Figs. 2A-B). Due to the fact that the first wall 120 and the second wall 124 extend outward from the interior of the container 100 along the longitudinal axis 150, the orientation of the plastic material in the base 108 increases as this allows the plastic material to further extend into the mold cavity for the base 108 during the formation of plastic particles, the particles straighten the crystalline. Typically, blow molding. As the orientation of the artificial increases, and so the structure can form, the greater the crystallinity of the plastic, the greater the rigidity of the plastic, which improves the structural integrity of the container 100 in the base 108. The structural integrity of the base 108 is important to enable the container 100 to withstand stringent process conditions hot filling. A similar process of increasing orientation is also described in the concurrent US Provisional Patent Application No. 60 / 671,459, filed April 15, 2005, the content of which is fully incorporated herein by reference.

[0032] It should be noted, initially formed that if the container 100 were being blown into the shape shown in Figs. 2A-B (this is bypassing the first

76P31023PL00

Stage 1), the base 108 would not be fully formed in the area near the supporting surface 118 and in the area near the third hinge 144. If the base 108 were not fully formed on the supporting surface 118, it could be formed uneven or a warped support surface 118, which could cause the container 100 to swing when placed upright on a flat surface. The reason for the incomplete formation of the base 108 is the way the containers are formed during stretch blowing. Since the container is stretch blow molded, the gas stretches the plastic material into a container mold, such as a container mold 100. If the mold includes a projection to form the base 108 shown in Figs. 2A-B, the plastic material would have to extend around this projection from the second hinge 122 down to the supporting surface 118 and to the third hinge 144 (see Figs. 2A-B). Contact with the mold would entrap the mold material in the area near the second hinge 122, and would not allow the material to form completely downwards to the area near the supporting surface 118, the first hinge 142 and the third hinge 144.

[0033] Forming the container 100 into the shape shown in the first stage also reduces the wall thickness of the base 108 and reduces the occurrence of thick amorphous plastic sections in the base 108, as opposed to the first stage. This may allow reducing the amount of plastic material in the base 108 without adversely affecting the performance of the container, and in some cases this technique improves the performance of the base 108.

Similarly, forming the container in the first stage may allow a more even distribution of the plastic material

76P31023PL00

EP 1 996 382 B1 to the base 108. In addition, the increased rigidity of the base 108 allows the first wall 120 and the second wall 124 to be inverted without significantly distorting the base network 108. Thus, forming the container 100 as described in the first step allows the base 108 to retain its appearance and stable standing on a flat surface after both inversions of the first wall 120 and the second wall 124.

while (not shown [0034] After blow molding the container into the shape of the first stage shown in Figs. 1A-B, the first wall 120 can be inverted around the first hinge 142 to the shape shown in the second stage as shown in Figs. 2A-B Fig. 2A is a side view of an exemplary container in a second step and Fig. 2B is a perspective view of the base of an exemplary container according to the present invention. During the inversion, force can be applied to the second wall 124 and to the section 126, the container 100 remains within the mold

In one embodiment, the inversion of the first wall 120 may occur in a blow molding process as late as possible so that the container 100 has the ability to cool as much as possible before pushing the container 100 out of the mold, because the warmer the container is during inversion, the greater the likelihood that the container folds in an undesirable place. Inversion can occur just before pushing to reduce the likelihood that the inversion will cause 100 undesirable folds or distortions to form in the container. A pneumatic cylinder (not shown) may be used to invert the first wall 120 by force on the second wall 124 and section 126. Alternatively, other mechanical means may be used for the inversion, as is known to those skilled in the art. When flipping over,

76P31023PL00

The folds 128 in the first wall 120 bend to facilitate inversion and prevent deformation of the base 108. The first wall 120 rotates around the first hinge 142 during its inversion from the first stage to the second stage. The first wall 120 also rotates around the second hinge 122 relative to the second wall 124 during inversion from the first stage to the second stage. After inverting the first wall 120, the first wall 120 slopes toward the interior of the container 100 relative to the longitudinal axis 150, and the second wall 124 slopes outwardly from the interior of the container 100 relative to the longitudinal axis 150, as shown in Figs. 2A-B.

[0035] The second stage is the stage at which the container 100 can be filled with the hot product. The base structure 108 in the second stage can be used to partially reduce the internal vacuum acting on the container 100 during the hot filling process. After the container 100 has been filled with the hot product and sealed with a closure such as a screw cap, but not limited to it, the product begins to cool inside the container 100. The cooling of the product creates an internal vacuum in the container 100 due to the reduction in the volume of the product due to the cooling and shrinkage of the product. Internal underpressure in the container

100 tends to cause the container 100 to collapse inward. In order to compensate for a portion of the internal underpressure inside the container 100, the position of the second wall 124 around the second hinge 122 can be changed. During this change of position, the folds 136 in the second wall

124 may bend to facilitate repositioning and prevent significant distortion of the base 108.

During inversion, the second wall 124 also rotates around the third hinge 144 relative to section 126. This change in position of the second wall 124 corresponds to the change

76P31023PL00

EP 1 996 382 B1 from the second stage (see Figs. 2A-B) to the third stage (see Figs. 3A-B). Alternatively, both the first wall 120 and the second wall 124 can be inverted prior to the hot filling process.

[0036] When inverting the second wall 124, force can be exerted on section 126 to invert the second wall 124 around the second hinge 122. This inversion also causes section 126 to rotate around the third hinge 144. This force can be exerted on the section 126 by means of an air cylinder or pneumatic rod activated by a cam or other machines. As the machine increases the force exerted on section 126, section 126 pivots about the third hinge 144 and the second wall 124 pivots about the second hinge 142 relative to the longitudinal axis 150. After being inverted, both the first wall 120 and the second wall 124 are inclined towards the inside of the container 100 relative to the longitudinal axis 150. The rigidity of the base 108, in particular in the area near the supporting surface 118 and the convex annular wall 132, prevents the base 108 from crumpling or deforming when the first wall 120 is turned over. Similarly, the rigidity of the base 108, in particular in the area near the first wall 120, the supporting surface 118 and the convex annular wall 132, prevent the base 108 from crumpling or deforming when the second wall 124 is inverted. The rigidity of the base 108 allows the first wall 120 and the second wall 124 to substantially maintain their shape after both inversions so that there is no significant distortion of the network of the first wall 120, second wall 124, section 126, or any other part of the base 108.

[0037] FIG. 3A shows a side view of an exemplary container in a third step, and FIG. 3B is a perspective view of the base of an exemplary container according to

76P31023PL00

EP 1 996 382 B1 of the present invention. Figs. 3A-B show the second wall 124 after changing position from the second stage to the third stage. During the change of position, the second wall 124 is moved from a position extending outwardly from the container 100 to a position extending inwardly of the container 100 relative to the longitudinal axis 150. The change in position causes the second wall 124 to rotate around the second hinge 122 and causes the second wall 124 to rotate around the third hinge 144 relative to section 126.

An inwardly directed repositioning of the second wall 124 reduces the volume within the container 100. This reduction in internal volume partially reduces the internal underpressure within the container 100 due to the volumetric contraction of the cooled product. The size of the volume reduced during the inversion of the second wall 124 refers to the volume of the area inside the base 108 of the container 100 bounded by the second wall 124 and section 126. The reduced volume refers to the difference in internal volume between the container 100 shown in Figs.

2A-B, with a second wall 124 extending outward from the interior of the container 100 and the container 100 shown in Figs. 3A-B with a second wall 124 extending inwardly towards the interior of the container 100. The reduction of pressure by inverting the base wall is also discussed in the simultaneous U.S. Patent Application No. 11 / 249,342 entitled "Adapted container base structure" filed October 14, 2005, the contents of which are incorporated herein by reference in their entirety.

[0038] Thus, the container 100 according to an exemplary embodiment of the present invention can compensate for a portion of the vacuum caused by the hot filling process and has sufficient rigidity in the base 108, which allows the container 100 to be in a stable state on a flat

76P31023PL00

It does not allow significant distortion of the network or deformation of the container 100 due to a change in the position of the first wall 120 and the second wall 124.

[0039] The embodiments and examples discussed herein are non-limiting examples.

[0040] The intention of the exemplary embodiments shown and discussed in this description is merely to provide those skilled in the art with the best method of implementing and using the invention known to inventors.

Nothing in this description should be construed as limiting the scope of the present invention. All examples presented are representative and not limiting. The exemplary embodiments of the invention described above can be modified or altered without departing from the scope of the invention, as will be understood by those skilled in the art in the light of the above information. Therefore, it goes without saying that, within the scope of the claims and their equivalents, the invention may be practiced in a different way than that which has been specifically described.

Graham Packaging Company, LP

Proxy:

76P31023PL00

EP 1 996 382 B1