US20080093330A1

US20080093330A1 - Container with Finish Ring

Info

Publication number: US20080093330A1
Application number: US11/550,648
Authority: US
Inventors: Richard Johnston; Joseph Labadie; Lance Novotny
Original assignee: Graham Packaging Co LP
Current assignee: Graham Packaging Co LP
Priority date: 2006-10-18
Filing date: 2006-10-18
Publication date: 2008-04-24
Also published as: CA2607023A1

Abstract

One embodiment of the invention relates to a container having a longitudinal axis and with a finish, shoulder, finish base, and a step. The shoulder has a wall thickness and is inclined away from the finish at a first angle with respect to a plane that is perpendicular to the longitudinal axis of the container. The a finish base extends from the bottom of the finish towards the shoulder and has a wall thickness. The finish base is inclined away from the finish at a second angle with respect to a plane that is perpendicular to the longitudinal axis of the container. The step extends from the finish base to the shoulder and is inclined away from the finish at a third angle with respect to a plane that is perpendicular to the longitudinal axis of the container. The step also has longitudinal height that is approximately the same as the wall thickness of the finish base; and. The container further includes a tubular sidewall extending from the shoulder, in direction that is generally parallel to the longitudinal axis of the container, and the step improves material distribution in the finish base and shoulder to contribute to uniform cooling thereof, thus achieving the perpendicularity of the finish with respect to the longitudinal axis of the container.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates generally to a blow-molded container, and more particularly to a uniformly shaped blow-molded container having increased strength in the neck and shoulder area.
2. Description of Related Art
A problem that commonly occurs in blow molding plastic containers is that hot plastic flows quickly through downwardly sloping areas, depositing an uneven amount of plastic throughout the mold. Also, as material moves axially during the blow-molding process, the material can be stretched too thin and fail to provide sufficient structural support. This is of particular concern in the upper portion of containers, including the finish area, shoulder area, and areas in between. Uneven flow of plastic can create a thinning, or weak spot, when the container is blow-molded, resulting in container weakness in these areas. Weakness can lead to, for example, a loss in perpendicularity in the finish and surrounding areas, such that the finish is no longer level on both sides of the container, and a decreased ability to accommodate top load forces. Ultimately, portions of the container may deform or collapse under pressure or during the capping process.
Plastic bottles having a slightly more pronounced slope between the finish and shoulder areas, often referred to as a step, are known in the art. These step regions typically have an angle of about 5 degrees, and are not clearly visible. The purpose of the step is to assist with removal of the bottle from the mold. Steps currently used in the art do not address issues relating to material distribution in plastic containers.
There is a need in the art for a container and method of manufacturing same that controls distribution of plastic throughout to prevent undesirable thinning and subsequent weakness in areas of the container, where the resulting container has an increased stability between the shoulder and neck finish areas.

BRIEF SUMMARY OF THE INVENTION

In one embodiment, the present invention is related to a container having a longitudinal axis and having a finish. The container includes a shoulder having a wall thickness, and the shoulder is inclined away from the finish at a first angle with respect to a plane that is perpendicular to the longitudinal axis of the container. The container further includes a finish base extending from the bottom of the finish towards the shoulder, the finish base having a wall thickness and being inclined away from the finish at a second angle with respect to a plane that is perpendicular to the longitudinal axis of the container.
Embodiments can additionally include a circumferential step extending from the finish base to the shoulder and being inclined away from the finish at a third angle with respect to a plane that is perpendicular to the longitudinal axis of the container, the step having a longitudinal height that is approximately the same as the wall thickness of the finish base. The container can have a tubular sidewall extending from the shoulder, in a direction that is generally parallel to the longitudinal axis of the container. The container step improves material distribution in the finish base and shoulder (finish area) to contribute to uniform cooling thereof, thus achieving the perpendicularity of the finish with respect to the longitudinal axis of the container.
In one embodiment of the invention, the step is approximately midway between the finish and the sidewall. The first angle of the shoulder can be from about 7 degrees to about 20 degrees, the second angle of the finish base can be from about 7 degrees to about 20 degrees, and the third angle of the step can be about 37 to about 50 degrees. The longitudinal height of the step can range from about 0.01 to about 0.10 inch. The wall thickness of the shoulder can be at least about 10-80% of the wall thickness of the finish base.
In another embodiment of the invention, the container can be an inverted-style container. The container can also be is adapted for use with a wide-diameter closure.
In another embodiment, the present invention is further related to a method of maintaining perpendicularity of a container finish by providing the features described herein. The step can be approximately midway between the finish and the sidewall, and the angle of the finish base or the angle of the shoulder with respect to a plane that is perpendicular to the longitudinal axis can be from about 6 degrees to about 18 degrees. The angle of the step can be about 25 to about 60 degrees with respect plane that is perpendicular to the longitudinal axis, and the wall thickness of the shoulder can also be least about 60-70% of the wall thickness of the finish base.
Other embodiments of the invention are related to a finish area for a blow molded container. The finish area includes a finish, a finish base extending outwardly from the finish, the finish base having a wall thickness, and a step adjacent to the finish base at an end opposite from where the finish base meets the finish, wherein the step has a longitudinal height that is approximately equal to the wall thickness of the finish base. The step also improves material distribution in the finish base and shoulder to contribute to uniform cooling thereof, thus achieving the perpendicularity of the finish area with respect to a longitudinal axis of the container. The step can have an angle of about 43 degrees with respect to plane that is perpendicular to the longitudinal axis of the container.
The finish area can include a shoulder area having a wall thickness, and the wall thickness of the shoulder can be about 60-70% of the wall thickness of the finish area. 17. The shoulder can have an angle of about 11 degrees with respect to a plane that is perpendicular to the longitudinal axis of the container. The finish base can also have an angle of about 11 degrees with respect to a plane that perpendicular to the longitudinal axis of the container.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the invention will be apparent from the following, more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings wherein like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements.

FIG. 1 illustrates a side perspective view of the container according one exemplary embodiment of the present invention;

FIG. 2 illustrates a plan view of the container according one exemplary embodiment of the present invention;

FIG. 3 illustrates a side view of the container according one exemplary embodiment of the present invention;

FIG. 4 illustrates an exploded view of the container of FIG. 3;

FIG. 5 illustrates a cross section taken along line 5-5 of FIG. 2; and

FIG. 6 illustrates an exploded view of the finish area of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention are discussed in detail below. In describing embodiments, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. While specific exemplary embodiments are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations can be used without parting from the spirit and scope of the invention.
An exemplary container 100 according to the present invention is illustrated by FIGS. 1-6. The illustrated container includes a neck finish 102, a finish base 104, a step 106, shoulder 108, and sidewall 110. The step 106 may also be referred to as a finish ring. Finish area 112 encompasses the upper portion of the container, including finish 102, finish base 104, step 106, and shoulder 108.
As shown by the Figures, finish base 104 is adjacent to and slopes downwardly away from neck finish 102 at a second angle β, and towards shoulder 108. The angle β is defined with respect to a plane that is perpendicular to the longitudinal axis L_Aof the container 100 (see FIGS. 4, 6). Next to the finish base 104 is the step or finish ring 106, which is positioned between the finish base 104 and the shoulder 108. Step 106 is inclined away from finish 102 and forms a third angle γ, the angle γ defined with respect to a plane perpendicular to the longitudinal axis L_Aof the container 100. Step 106 is circumferential, meaning that it extends along the circumference of container 100. In some embodiments, the step 106 extends along the entire circumference of the container 100. Shoulder 108 is adjacent the step 106 and joins the tubular container sidewall 110. Shoulder 108 is inclined away from finish 102 at a first angle α, the angle α defined with respect to a plane that is perpendicular to the longitudinal axis of the container 100. Shoulder 108 meets container sidewall 110. As shown in FIG. 1, sidewall 110 can be tubular and extends in a direction that is generally parallel to the longitudinal axis L_Aof the container 100.
Both the finish base 104 and the shoulder 108 each have a wall thickness. (See FIG. 5.) The wall thickness of the shoulder T_Scan range from about 10 to about 80% of the wall thickness of the finish base 104 T_F. In one embodiment, the wall thickness of the shoulder T_Scan be about 60-70% of the thickness of the finish base 104.
As most clearly visible in FIG. 6, shoulder 108 forms a first angle α where the shoulder meets step 106. Angle α can have a value ranging from about 7 to about 20° or from about 6 to about 18°. In one exemplary embodiment, angle α is about 11°. Similarly, step or finish ring 106 forms an angle γ where the step meets the finish base 104. Angle γ can have a value ranging from about 37 to about 50° or from about 25 to about 60°. For example, angle γ can be about 43°. Finish base 104 forms angle β where the finish base 104 meets finish 102. Angle β can have a value that ranges from about 7 to about 20° or from about 6 to about 18°. In accordance with one embodiment of the present invention, angle β is about 11°.
Factors that may affect angles α, β and γ are, for example, the flowability of the manufacturing material and the cooling properties of the material (e.g. how quickly the material cools.) Angles β and γ in particular can help with the flow of the material, and can be altered based on the properties of the plastic being used and the desired specifications, dimensions, and/or uses of the container to be produced.
In order to maintain container integrity, especially with respect to the finish area 112 that includes the neck finish 102, finish base 104 and shoulder area 108, step or finish ring 106 is inserted between the finish base 104 and the shoulder 106. The step/finish ring 106 contributes to uniform distribution of material in the manufacturing process. For example, the addition of the step 106 allows hot plastic to flow into the region of the step 106 and aid in material distribution as the plastic is stretched and blown to form the container 100. The angle γ assists with the flow of plastic into the step 106.
The step also has a height H_S(FIG. 6), which can be adjusted depending on the type of container and the amount of material that is needed. The step height H_Scan range from about 0.01 to about 0.10 inch. In one embodiment of the invention, the step height H_Scan be about 0.03 inch. The longitudinal height of the step H_Scan also be about the same as the wall thickness of the finish base T_F.
The distribution of plastic material in the finish area 112 is at least partly determined by the height of the step. The greater the step height H_S, the more material that flows into the finish area 112. Thus, if it is advantageous for a container to have increased strength in the upper portion of the container (including the finish area 112), the height of the step H_Scan be increased so that more plastic is present in the finish area 112.
The container according to some embodiments of the invention described herein can be an inverted-style container. An inverted container may need more strength in the upper portion of the container to support the weight of the container and contents without collapse. The increased material and strength imparted by step 106 to the finish area 112 allows the finish area to maintain perpendicularity and stay level. The ability to maintain perpendicularity is of special importance in inverted style containers. Also, the increased strength imparted by the step can enhance top loading ability for all containers. The container of the present invention can also be adapted for use with wide-diameter closures.
In order to provide a complete idea of the container as described herein, the following are measurements according to one exemplary embodiment, such as that shown in FIG. 4. The diameter of the container opening D_Ocan be about 0.959 inches. The diameter of the container D_C, measured as the distance between the sidewalls 110, can be about 2.2 inches. The distance D_Staken from the center of the container, shown at exemplary pt C_Malong the longitudinal axis L_A, to the step 106 where the step meets the shoulder 108 (step-shoulder junction), can be about 0.881 inches. The length of the finish base L_F, as measured from the point where the finish base 104 meets the finish 102 (finish-finish base junction) to where the finish base 104 meets the step 106 (finish base-step junction) can be about 0.219 inches. As illustrated in FIG. 4, the step 104 is approximately halfway between the finish-finish base junction, and the sidewall 110. Thus, the distance L_Sfrom the step 104 at the step-shoulder junction to the sidewall 110 can also be about 0.219 inches.
Certain embodiments of the present invention are further related to a method of maintaining perpendicularity of a finish of a blow molded container by providing the container described herein. Containers, particularly containers having a finish area with a large diameter, are susceptible falling on one side, thus becoming crooked. This problem is often experienced with inverted-style containers, that may droop to one side due to weakness in the finish area. Falling or tilting can result from uneven cooling of the plastic material due to uneven distribution of plastic in the finish area 112. By providing the container with finish area 112 having step 106 as set forth in the present invention, material is distributed more evenly, cools more evenly, and this prevents collapse of the finish area 112 on one side. Thus, perpendicularity of the finish area 112 is maintained.
Embodiments of the present invention are additionally related to a finish area 112 for a blow molded container, as most clearly shown in FIGS. 4 and 6 and discussed throughout the present specification.
Embodiments of the invention as described herein can be particularly advantageous in containers where the finish area 112, has a large diameter. For example, containers having an extended finish base 104 where the length of the finish base L_Fis longer than is many standard containers, can be improved by manufacture using the method described herein. For example, one challenge currently experienced in manufacturing is that the finish area can collapse upon itself or recede in the direction of the container body. Such a dent or recession can reduce the distance between the finish and the shoulder. A reduction in this distance can create problems with respect to closure clearances. The addition of a step or finish ring 106 to finish area 112 contributes to uniform distribution of plastic material in finish area 112 and can assist in overcoming some of the difficulties encountered during manufacture. The angled step 106 slows the material flow so that a greater amount of plastic is retained in finish area 112. After blow molding, the finish area 112 of the container 100 is thicker and has increased strength. This prevents the finish area 112 from tilting to one side and/or collapse of the container under pressure. The addition of the step/finish ring 106 stabilizes the finish area which can increase the cycle time of manufacture.
The container 100 has a one-piece construction and can be prepared from a monolayer plastic material, such as a polyamide, for example, nylon; a polyolefin such as polyethylene, for example, low density polyethylene (LDPE) or high density polyethylene (HDPE), or polypropylene; a polyester, for example polyethylene terephthalate (PET), polyethylene naphthalate (PEN); or others, which can also include additives to vary the physical or chemical properties of the material. For example, some plastic resins can be modified to improve the oxygen permeability. Alternatively, the container can be prepared from a multilayer plastic material. The layers can be any plastic material, including virgin, recycled and reground material, and can include plastics or other materials with additives to improve physical properties of the container. In addition to the above-mentioned materials, other materials often used in multilayer plastic containers include, for example, ethylvinyl alcohol (EVOH) and tie layers or binders to hold together materials that are subject to delamination when used in adjacent layers. A coating may be applied over the monolayer or multilayer material, for example to introduce oxygen barrier properties. In an exemplary embodiment, the present container is prepared from PET.
The container can be manufactured by blow molding, such as extrusion blow molding, stretch blow molding, and injection blow molding. In extrusion blow molding, A molten tube of thermoplastic material, or plastic parison, is extruded between a pair of open blow mold halves. The blow mold halves close about the parison and cooperate to provide a cavity into which the parison is blown to form the container. As formed, the container can include extra material, or flash, at the region where the molds come together, or extra material, or a moil, intentionally present above the container finish. After the mold halves open, the container drops out and is then went to a trimmer or cutter where any flash of moil is removed. The finished container may have a visible ridge formed where the two mold halves used to form the container came together. This ridge is often referred to as the parting line.
In stretch blow molding, a preformed parison, or preform, is prepared from a thermoplastic material, typically by an injection molding process. The preform typically can include threaded end, which becomes the threads of the container. Alternatively, the threaded finish can be formed during blow molding. The perform is positioned between two open blow mold halves. The blow mold halves close about the perform and cooperate to provide a cavity into which the preform is blown to form the container. After molding, the mold halves open to release the container. The container can then be sent to a trimmer where the moil, or extra plastic material above the blown finish, is removed.
In injection blow molding, a thermoplastic material is extruded through a rod into an inject mold to form a parison. The parison is positioned between two open blow mold halves. The blow mold halves close about the parison and cooperate to provide a cavity into which the parison is blown to form the container. After molding, the mold halves open to release the container.
The embodiments illustrated and discussed in this specification are intended only to teach those skilled in the art the best way known to the inventors to make and use the invention. Nothing in this specification should be considered as limiting the scope of the present invention. All examples presented are representative and non-limiting. The above-described embodiments of the invention may be modified or varied, without departing from the invention, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the claims and their equivalents, the invention may be practiced otherwise than as specifically described.

Claims

1. A container having a longitudinal axis and comprising:

a finish;

a shoulder having a wall thickness and being inclined away from the finish at a first angle with respect to a plane that is perpendicular to the longitudinal axis of the container;

a finish base extending from the bottom of the finish towards the shoulder, the finish base having a wall thickness and being inclined away from the finish at a second angle with respect to a plane that is perpendicular to the longitudinal axis of the container;

a circumferential step extending from the finish base to the shoulder and being inclined away from the finish at a third angle with respect to a plane that is perpendicular to the longitudinal axis of the container, the step having a longitudinal height that is approximately the same as the wall thickness of the finish base; and

a tubular sidewall extending from the shoulder, in direction that is generally parallel to the longitudinal axis of the container

wherein the step improves material distribution in the finish base and shoulder to contribute to uniform cooling thereof, thus achieving the perpendicularity of the finish with respect to the longitudinal axis of the container.

2. The container of claim 1, wherein the step is approximately midway between the finish and the sidewall.

3. The container of claim 1, wherein the second angle of the finish base is from about 7 degrees to about 20 degrees.

4. The container of claim 1, wherein the third angle of the step is about 37 to about 50 degrees.

5. The container of claim 1, wherein the longitudinal height of the step is about 0.01 to about 0.10 inch.

6. The container of claim 1, wherein the first angle of the shoulder is from about 7 degrees to about 20 degrees.

7. The container of claim 1, wherein the wall thickness of the shoulder is at least about 10-80% of the wall thickness of the finish base.

8. The container of claim 1, wherein the container is an inverted-style container.

9. The container of claim 1, wherein the container is adapted for use with a wide-diameter closure.

10. A method of maintaining perpendicularity of a finish area of a blow molded container comprising:

providing a container comprising:

a finish;

a shoulder having a wall thickness and inclining away from the finish a first angle with respect to a plane that is perpendicular to the longitudinal axis of the container;

a finish base having a wall thickness and inclining away from the finish at a second angle with respect to a plane that is perpendicular to the longitudinal axis of the container, the finish base extending from the bottom of the finish towards the shoulder,

a circumferential step between the finish base and the shoulder, and inclining away from the finish at a third angle with respect to a plane that is perpendicular to the longitudinal axis of the container, the step having a longitudinal height that is approximately equal to the wall thickness of the finish base, and,

a tubular sidewall extending from the shoulder in direction that is generally parallel to the longitudinal axis of the container; and

forming the step

wherein the step improves material distribution in the finish base and shoulder to contribute to uniform cooling thereof, thus achieving the perpendicularity of the finish area with respect to a longitudinal axis of the container.

11. The container of claim 10, wherein the step is approximately midway between the finish and the sidewall.

12. The container of claim 10, wherein the angle of the finish base or the angle of the shoulder with respect to a plane that is perpendicular to the longitudinal axis is from about 6 degrees to about 18 degrees.

13. The container of claim 10, wherein the angle of the step is about 25 to about 60 degrees with respect plane that is perpendicular to the longitudinal axis.

14. The container of claim 10, wherein the wall thickness of the shoulder is at least about 60-70% of the wall thickness of the finish base.

15. A finish area for a blow molded container comprising:

a finish;

a finish base extending outwardly from the finish, the finish base having a wall thickness, and

a step adjacent to the finish base at an end opposite from where the finish base meets the finish, the step having a longitudinal height that is approximately equal to the wall thickness of the finish base

16. The finish area of claim 15, further comprising a shoulder area having a wall thickness, wherein the wall thickness of the shoulder is at least about 60-70% of the wall thickness of the finish area.

17. The finish area of claim 15, wherein the step further comprises an angle of about 43 degrees with respect to a plane that is perpendicular to the longitudinal axis of the container.

18. The finish area of claim 15, wherein the finish base further comprises an angle of about 11 degrees with respect to a plane that perpendicular to the longitudinal axis of the container.

19. The finish area of claim 15, wherein the shoulder further comprises an angle of about 11 degrees with respect to a plane that perpendicular to the longitudinal axis of the container.

20. The finish area of claim 15, wherein the height of the step is about 0.03 inch.