MXPA06007081A

MXPA06007081A - A plastic container or a preform.

Info

Publication number: MXPA06007081A
Application number: MXPA06007081A
Authority: MX
Inventors: Thomas E Nahill
Original assignee: Graham Packaging Pet Tech
Priority date: 2003-12-24
Filing date: 2004-12-23
Publication date: 2006-09-04
Also published as: WO2005066034A1; CN1898134A; EP1706329A1; US20050142311A1; AU2004312420A1; BRPI0418108A; CA2551314A1

Abstract

A finish assembly for a plastic container or preform includes a plastic neck having an open end surrounded by an external flange (22). The flange has an open axially facing channel proximal to an outer surface of the neck. A plastic finish ring has an annular body, an inner surface opposed to the outer surface of the neck, an outer surface with at least one external thread, bead or other means for attachment of a closure, and an annular lip (36) extending into the channel. The channel may be formed in part by a radially inwardly extending conical surface on the flange, and the lip has a radially outwardly extending conical surface in facing engagement with the radially inwardly facing conical surface on the flange to seal the finish ring against the flange against entry of liquid between the finish ring and the neck.

Description

CONTAINER OR PLASTIC PREFORM FIELD OF THE INVENTION The present invention is directed to finishes for plastic containers or preforms, to preform assemblies for blow molded plastic containers, to blow molded plastic containers of such preform assemblies, and to methods for manufacturing such finishes, preform assemblies and containers.

BACKGROUND OF THE INVENTION In the manufacture of plastic containers, it is conventional to injection-molding or compression molding a container preform having a body and a finish with one or more external threads or other closure joining means. The finish of the preform is usually molded to its final geometry, while the body of the preform is subsequently blow molded to the desired geometry of the container body. The preform can be monolayer or single layer construction, or it can be multilayer construction wherein one or more intermediate layers in the preform body may or may not extend in the finishing area of the preform. U.S. Patent Nos. 4,609,516; 4,710,118 and 4,954,376 illustrate the injection molding of preforms of the container REF. 173633 multi-layer. Shaping the finishing portion of the container as part of the preform presents a number of problems. For example, when the preforms are formed by injection molding, the plastic material is normally injected into a mold cavity at the closed end of the preform body and must first flow into the area along the sides of the preform cavity. , to form the preform body of relatively thin walls, and then in the area in which the finish is molded, to form the substantially thicker finishing portion. Because it is located at the end of the flow path, it can be difficult to completely fill the relatively more contoured and thicker finishing portion. Also, the finish normally requires a more accurate and more stable dimension than the body - of the preform, which can lengthen the duration of the molding process time cycle. Furthermore, where the finishing portion of the preform is of the same material as at least the outer layers of the preform body, this may limit the ability to obtain more desirable performance characteristics in the finish. For example, when the preform is of polyester construction, such as polyethylene terephthalate (PET), the finishing portion of the preform can be fully or partially crystallized to improve the operating characteristics of the finishing area, particularly in container applications. Higher temperature (for example, hot filling, pasteurization, filling, etc.). However, the requirement that the finish be of the same material such as at least the outer layers of the preform body (in a multilayer preform) can limit the design, fabrication and / or performance characteristics of the preform or container. . US Applications Nos. Of Series 10 / 351,671; 10 / 375,376; 10 / 375,758 and 10 / 403,415, assigned to the assignee of the present application, describe finishing assemblies for preforms and containers in which the neck of the preform has an external flange around its open end, and a separate plastic finishing ring is provided. mounted on the neck of the preform abutting the external flange. The finishing ring has one or more external threads or other means for securing a closure, and may be of a plastic construction different from the plastic construction of the preform. The body and neck of the preform can be of relatively thin plastic construction, while the finishing ring (alone or together with the neck) forms a thick construction. However, the liquid that spills on the finish during filling of the container may flow between the finishing ring and the flange of the preform, and collect between the finishing ring and the neck of the preform. Such fluid is unpleasant and can promote the growth of the mold. It will be desirable to provide a finishing assembly for a plastic preform or container, a method for manufacturing a plastic preform or container, and a preform assembly that reduces or eliminates the likelihood of fluid leakage between the finishing ring and the neck. of the preform / container.

BRIEF DESCRIPTION OF THE INVENTION According to one embodiment of the invention, a method for manufacturing a preform assembly is provided. A plastic preform is provided having a body with a closed end, and a neck extending from the body, the neck having an open end and a flange extending radially outwardly, surrounding the open end. The flange has an open channel close to the outer surface of the neck. A finishing ring is provided with an annular body and an external surface with a joining portion to ensure a closure. An annular flange extends from the body of the finishing ring. The finishing ring and the preform are mounted such that the ring is received on the outer surface of the neck and the annular flange is received in and engages in at least a portion of the channel.

According to another embodiment of the invention, a finishing assembly for a plastic container or preform is provided. The assembly includes a plastic collar having an open end surrounded by an external flange, the flange having an open channel proximate to an outer surface of the neck. The assembly further includes a plastic finishing ring having an annular body with an inner surface positioned opposite the outer surface of the neck, and an outer surface having a connecting portion for securing a closure. An annular flange on the finishing ring extends into and engages at least a portion of the channel. In another embodiment, a preform assembly is provided for blow molding a plastic container. The assembly includes a plastic preform having a body with a closed end that is blow molded to form a container, and a neck that extends axially from the body and has an open end with a radially and externally extending flange. The flange has an annular groove that forms an open channel in a lower surface of the flange. The assembly further includes a finishing ring having an annular body placed on the neck of the preform, and an external surface having at least one external thread. An annular rim on the ring extends into and engages at least a portion of the channel.

In several described embodiments of the invention, the coupling portions of the flange and channel comprise one or more facing surfaces that allow the sealing of the finishing ring against the flange. The channel, which can be removed from or molded into the lower part of the flange, produces a radially extending upper flange portion and an external flange projection projecting downward or to the flange. The outer flange flange is generally aligns axially with the channel (and with the central axis of the neck of the preform). This flange on the flange has at least one facing surface that is flush with an opposing facing surface on the annular flange of the finishing ring, to seal the ring and the flange. The facing surfaces can, for example, form conical coupling surfaces. The facing surfaces can extend to the outer surfaces of the finishing ring and flange, thereby delaying or preventing the entry of any fluid between the neck of the preform and the finishing ring. The flange of the finishing ring and the channel of the preform may abut completely, or there may be a separation between at least a portion of the flange and channel as long as another portion seals the flange and channel. The flange and channel may alternately have stepped facing surfaces. Generally, each of the finishing ring and the neck of the preform are annular bodies having axially elongated internal and external annular coupling surfaces, respectively. The finishing ring thus forms a collar around the neck of the preform. The finishing ring can be used to provide a substantially coarser finishing portion to the neck of the preform or container, compared to a flank of the container. The finishing ring can be made of a different plastic material than the neck of the preform or container, thus providing various operating characteristics. The finishing ring can be treated (for example, thermally) before or after its assembly with the neck, to provide various properties (even if it is made of the same material as the neck). The finishing ring can be slid over the lower end and over the neck of the preform, followed by the blow molding of the preform body to form a container. Various other embodiments of the invention can be understood from the following description and appended figures.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 is an elevated view of a / preform assembly according to an embodiment of the invention; Figure 2 is an exploded perspective view of the preform assembly illustrated in Figure 1; Figure 3 shows a fragmentary sequential view of the neck of the preform. Figures 3A-3B are a fragmentary sectional view taken substantially along line 3-3 in Figure 1; Figure 3A is a fragmentary sectional view on an enlarged scale of the upper end of the neck of the preform illustrated in Figure 3; Figure 3B is a fragmentary sectional view on an enlarged scale of the upper end of the finishing ring illustrated in Figure 3; Figures 4 and 5 are fragmentary sectional views, similar to Figure 3, but illustrating modified embodiments of the finishing ring and neck of the preform; Figure 6 is a perspective view of a preform and finishing ring for providing a preform assembly according to another embodiment; Figure 7 is an enlarged fragmentary sectional view of the neck of the preform and finishing ring taken substantially along line 7-7 in Figure 6; and Fig. 8 is a fragmentary and partially schematic sectional view of a finishing ring and neck of the preform, similar to the preform assembly shown in Figs. 6-7, and further illustrates a portion of blow molded container made of the body portion of the preform.

DETAILED DESCRIPTION OF THE INVENTION Figures 1-3B illustrate a preform assembly 10 according to one embodiment of the invention. The assembly 10 includes a preform 12 and a finishing ring 14 mounted thereon. The preform 12 includes a body 16 with a closed lower end 18 and an integrally formed neck 20 with an external flange 22 extending radially and externally from the open end of the neck. The neck 20 is generally cylindrical in construction, and the flange 22 is circumferentially continuous and substantially perpendicular to the central longitudinal axis of the neck of the preform 20. (shown by line 3-3 in Figure 1). An open channel (or notch) 24 (Figures 3 and 3A) is formed on the lower surface 33 of the flange 22, such as that which is molded into the flange or formed therein in a post-molding operation, thus leaving an upper portion 25 on the channel and a lower flange 23 or projection extending downwardly on the flange 22. As best seen in Figure 3A, the channel 24 has a surface that is oriented generally radially and externally 26 which is preferably a continuation of the radially and externally oriented surface 28 of the neck of the preform 20, an annular lower surface 30 adjacent (and substantially perpendicular) to the surface 26, and a surface that is oriented radially and internally inclined 32 (less than 90) ° with respect to the axis of the central neck) (see Figure 3A) extending from the outer edge of the lower surface 30 of the channel. In this example, the inclined surface 32 is conical in construction with respect to the longitudinal axis of the neck. The conical surface 32 is preferably at an angle of about 30 ° to the central axis of the neck of the preform 20. The annular bottom surface 30 of the channel 24 preferably remains in a plane substantially perpendicular to the axis of the neck 20. Similarly, the lower annular surface 33 of the flange of the outer flange 23 preferably remains in a plane substantially perpendicular to the axis of the neck 20. The finishing ring 14 is preferably of molded plastic construction, and can be of a plastic material equal to or different from the preform 12. If Using the same material, the molded finishing ring can be processed differently than the preform to provide various properties. The finishing ring 14 has an elongated annular body 34 with an axially extending upper flange, integrally formed 36. The body of the ring 34 and the flange 36 are preferably circumferentially continuous. The flange 36 has an internal surface 38 (FIG. 3B) preferably formed as an extension of the inner surface 40 of the ring body 34, both preferably being cylindrical. The rim 36 also has an upper end surface 42, which preferably remains in a plane perpendicular to the longitudinal axis of the ring 14 (same as the neck axis), and a radially and externally oriented conical surface 44 extending from the outer edge of the upper surface 42. The conical surface 44 is preferably complementary to the conical surface 32 on the flange 23 of the flange of the preform, preferably at an angle of approximately 30 °, such that the two facing surfaces abut yes in sealing coupling. A second upper surface 46 in the ring 14, which can be parallel to or angled with respect to the upper surface 42, extends from the conical surface 44 to the radially outer surface 48 of the ring body 34. The ring body 34 also it includes at least one external thread, edge or other means 50 to ensure a closure to the final container (Figure 8). In the exemplified embodiments illustrated in the figures, the ring body 34 also includes an annular rim 52 for coupling by means that indicate tampering in the closure, and a support flange 54 for facilitating subsequent handling of the preform and container. The preform 12 is preferably formed in a compression or injection molding operation. The finishing ring 14, which is preferably formed by itself in a convenient plastic molding operation, can be slid over the closed end of the preform such that the radially inner surface 40 of the finishing ring 14 is in narrow sliding engagement with the radially outer surface 28 of the neck of the preform 20. The above-noted pending applications describe various techniques for mounting the finishing ring 14 on the neck 20 and securing the finishing ring to the neck, such as by interference pressure fitting, alone or reinforced by adhesive and / or ultrasonic welding. The finishing ring assembly 14 on the neck of the preform 20 continues until the rim 36 in the finishing ring 14 is received within the channel 24 in the flange 22 of the neck of the preform and the conical surfaces 44, 32 are placed in adjacent confronting coupling. Such facing engagement abutting the surfaces 44, 32 helps to prevent any flow of liquid between the opposite surfaces of the finishing ring and the neck of the preform. The axial dimension (depth) of the channel 24 can be smaller than the axial dimension (height) of the finish flange 36 such that there is a gap 56 (FIG. 3) between the flange of the preform 22 and the surface of the finishing ring 46 when mounted, such as to help ensure that the conical facing surfaces 44, 32 are in seated engagement. In Figure 3, the spacing 56 is between the lower flange 23 (see Figure 3A) of the flange 22 and the upper surface 46 (see Figure 3B) of the finishing ring 14. Figures 4 and 5 illustrate other preform assemblies. , 62 according to the respective modified embodiments of the invention. The reference numbers in Figures 4 and 5 which are identical to those in Figures 1-3B indicate identical or related components. The main difference between the preform assembly 60 in Figure 4 and the preform assembly 10 in Figures 1-3 is that the flange of the preform 22a and / or the rim of the finishing ring 36a is / are dimensioned such that there is the adjoining coupling for both lower surfaces 30, 33 (FIG. 3A) in the flange 22a and upper surfaces 42, 46 (FIG. 3B), respectively, in the finishing ring 14a. That is, the channel flange and the rim of the finishing ring are dimensioned to eliminate the spacing 56 in FIG. 3. As another alternative, there may be a proportionate spacing between the surfaces 30, 42 (FIGS. 3A and 3B) in the embodiment In figure 5, in figure 5, the flange of the neck 22b has a channel in which the conical surface 32b extends to the outer edge of the flange, and the conical surface 44b in the rim of the finishing ring 36b extends to the outer surface of the finishing ring, ie, that the coupling surfaces 33 (Fig. 3A) and 46 (Fig. 3B) are eliminated. Figures 6-8 illustrate another embodiment wherein the assembled preform and neck finish are used to form a blow molded container 6. Figure 6 illustrates a finishing ring 14c, shown separately below, and assembled with a preform 12c in the upper portion of the figure. Figure 7 is an enlarged fragmentary sectional view of the neck of the assembled preform 20c and the finishing ring 14c of Figure 6. Figure 8 shows the assembly of Figures 6-7 after blow molding the preform body 16c for forming a container body 60c. The resulting container 64 thus includes the neck of the unexpanded preform 20c integral with the container body 60c, and the finishing ring 14c placed on the neck 20c. The preforms can be of any suitable plastic construction, such as a single-layer PET construction or multi-layer construction with the PET layers alternating with barrier layers such as ethylene vinyl alcohol (EVOH) or nylon. The preforms can be injection molded or compression molded.

Likewise, the finishing rings can be of plastic construction molded by injection or compression. By providing the finishing rings separately from the preforms, the finishing rings can be of any desired material construction, or either the same as or more preferably different from the construction of the material of the preforms. For example, the construction of the finishing ring can be PET, post-consumer resin (PCR), process fragmentation (REG), polypropylene (PP), polyethylene (PE) or polyethylene naphthalate (PEN). Where the finishing ring. is of polyester construction (eg, PET, PEN or process fragmentation), the finishing ring can be completely or partially crystallized when molded. This can be achieved by using materials of rapid crystallization, or conditions of the adjustment process suitable for manufacturing the finishing ring, such as a high molding temperature, slow molding cooling, areas heated in the mold cavity, etc. The finishing ring can alternatively be completely or partially crystallized in a post-molding operation. In other words, the material and manufacturing conditions of the finishing ring can be selected separately from the conditions of the material and manufacture of the preform to obtain the desired operating characteristics in the finishing area of the preform and the final container. In addition, the preform can be molded with thin wall sections without having to adjust the flow of material in a thick finish area, which reduces material cost and molding cycle time. The finishing ring is secured to the neck of the preform by interference fit (e.g., snap fit or shrink fit), adhesive or solder. The finishing ring and / or the neck of the preform can be provided with suitable means to prevent the ring from rotating in the neck. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention described herein. It is desired that the specification and examples be considered as exemplary only, with a true scope of the invention which is indicated by the following claims.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims

CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. Method for manufacturing a preform mold for blow molding a container, characterized in that it comprises the steps of: (a) providing a preform of plastic having a body with a closed end and a neck extending from the body, the neck having an open end and a flange extending radially outwardly surrounding the open end, (b) providing a finishing ring having an annular body, an outer surface with a joining portion for securing a closure, and (c) mounting the finishing ring to the preform by means of a sliding coupling therebetween such that the finishing ring is received on the outer surface of the neck, wherein the neck furthermore has a flange extending downwardly in the flange, the flange and the flange extending downwards form an open channel next to an outer surface of the neck, and the finishing ring further has an annular ridge extending from the body, and in step (c) and the annular rim is received in and engages at least a portion of the channel . Method according to claim 1, characterized in that the flange and the channel have facing surfaces which engage when the flange is received in the channel. Method according to claim 2, characterized in that the facing surfaces are inclined with respect to a central axis of the neck. . Method according to claim 3, characterized in that the channel and flange have conical facing surfaces. Method according to claim 3, characterized in that the facing surfaces extend to the outer surfaces of the finishing ring and flange. Method according to claim 1, characterized in that there is a separation between at least a portion of the flange and finishing ring after step (c). Method according to claim 1, characterized in that the flange and channel have facing surfaces that are completely abutting after the step (c). Method according to claim 2, characterized in that the flange and the flange extending downwards form a first stepped facing surface which is coupled to a second stepped facing surface formed by the annular flange and the upper edge surface of the annular body . Method according to claim 1, characterized in that the finishing ring and neck of the preform have internal and external annular coupling surfaces, respectively. Method according to claim 1, characterized in that the joining portion of the finishing ring comprises a radially thickened threaded portion. Method according to claim 1, characterized in that step (a) is performed by injection or compression molding. Method according to claim 1, characterized in that it is followed by the step of: (d) blow molding a container from the preform. 13. Finish assembly for a plastic container or preform for blow molding a plastic container, characterized in that it comprises: (a) a plastic neck having an open end surrounded by an external flange, a flange extending downwardly in the flange, the flange and the flange extending downwards form an open channel close to an outer surface of the neck, and (b) a plastic finishing ring having an annular body, an outer surface with a joining portion for securing an closure, and an annular flange extending into and engaging at least a portion of the channel, wherein the outer surface of the neck is cylindrical and the finishing ring has an internal cylindrical surface opposite the outer cylindrical surface of the neck. 14. Finishing assembly according to claim 13, characterized in that the flange and channel have facing surfaces engaged to seal the finishing ring to the flange. 15. Finishing assembly according to claim 14, characterized in that the facing surfaces are inclined with respect to a central axis of the neck. 16. Finish assembly according to claim 15, characterized in that the channel and flange have tapered facing surfaces. 17. Finishing assembly according to claim 13, characterized in that there is a separation between at least a portion of the flange and finishing ring. 18. Finish assembly according to claim 13, characterized in that the facing surfaces of the flange and channel abut completely. 19. Finish assembly according to claim 14, characterized in that the flange and the flange extending downwardly form a first stepped facing surface engaging a second stepped facing surface formed by the annular flange and the upper edge surface of the second flange. ring body. 20. Finish assembly according to claim 13, characterized in that the joining portion of the finishing ring comprises a radially thickened threaded portion. 21. Finishing assembly according to claim 13, characterized in that the finishing ring and neck are in snap-fit engagement.