MXPA06011100A - Preform assembly, container assembly, and method of manufacture - Google Patents

Abstract

A method of making a preform assembly (20) including providing a finish ring (24) of plastic construction, placing the finish ring onto a core pin (52), introducing a preform polymer (64)into a mold cavity that includes the core pin, and compression molding the preform polymer (64) to the finish ring. A resulting preform assembly, and container assembly blow-molded from the preform assembly, are also disclosed.

Description

ASSEMBLY OF PREFORM, ASSEMBLY OF CONTAINER, AND MANUFACTURE METHOD FIELD OF THE INVENTION The present invention is directed to preform assemblies for container assemblies of blow molded plastic, to blow molded plastic container assemblies of such preform assemblies, and to methods for making such preform assemblies. and assemblies -of container.

BACKGROUND OF THE INVENTION In the manufacture of plastic containers, it is conventional to mold by "compression or injection molding a container preform", which has a body and a neck finish with one or more external threads or other means of attachment. closing. The preform neck finish is typically molded to its final geometry, while the body or the preform is subsequently blow molded to the desired geometry of the container body. The preform may be of a monolayer construction, or it may be of multiple layer construction in which one or more intermediate layers in the preform body may or may not extend into the pre-orma neck finish. Patents in the United States 4, 60-9, 51-6, 4,710,118 and 4,954,376 illustrate the injection molding of preferentially Ref. 17O38 container -of multiple layers. The molding of the finished neck portion of a container as a part of the container preform has a number of problems. For example, when the preforms are formed by injection molding, the plastic material is typically injected into a mold cavity at the closed end of the preform body, so that the material must flow along the sides of the mold. the preform mold cavity in the area in which the neck finish is molded. The neck finish typically requires more accurate and stable sizing than the body of the preform, which can limit the cycle time, the molding process or preform. In addition, the neck finish of the preform is of the same material as a preform-monolayer body, and of the same material as at least the outer layers of a preform body of multiple layers, which limits the ability to obtain the characteristics of more desirable material in the neck finish. When the preform is of polyester construction, such as polyethylene terephthalate (PET), the preform end of the preform can be completely or partially crystallized to improve the operating characteristics of the neck finish area, particularly in the applications -of hot filling container. However, the requirement that the neck finish be of the same material as at least the outer layers of a multi-layer preform body still limits the design capabilities of the preform manufacturing.

BRIEF DESCRIPTION OF THE INVENTION A production method of a preform assembly in accordance with one aspect of the present invention includes providing a plastic-finished ring on a one-molded, compression-molded core pin and compression-molding. a plastic preform in the ring of - determined in the mold. According to a second aspect of the present invention, a preform assembly for blow molding a container assembly is provided, which includes a molded plastic end ring and a plastic preform molded by compression to the finished ole end ring. so that a neck portion of the plastic preform radially internally couples the ring < 3e finished. In accordance with a third aspect of the invention, there is provided a blow molded container assembly of a preform assembly which is produced from compression molding a preform to a molded plastic finish ring. The container assembly includes the molded plastic end ring, and a plastic container having a neck portion thereof radially engaging the end ring internally.

BRIEF DESCRIPTION OF THE FICURES The invention, together with. objects, features, advantages and additional aspects thereof, will be better understood from the following description, the appended claims and accompanying figures, in the Figure: Figure 1 illustrates a side elevational view of a preform assembly in accordance with an exemplary embodiment of the present invention; Figure 2 illustrates a side elevational view 15 of a blow molded container assembly of the preform assembly of Figure 1, in accordance with another exemplary embodiment of the present invention; Figure 3 illustrates a side elevational view of a finishing ring for the preform and container assemblies of Figures 1 and 2; . Figure 4 illustrates a top view of the finishing ring of Figure 3; Figure 5 illustrates a cross-sectional view of the finishing ring of Figure 3, taken along the line "5-5; Figure 6A illustrates a compression molding apparatus for use in accordance with an exemplary method of the present invention, wherein the apparatus is displayed in an open position in which a charge of preform material is located within a mold cavity • and a pre-fabricated finished ring is loaded onto a core pin; Figure 6B illustrates the compression molding apparatus of Figure d wherein the apparatus is shown in a closed position in which the preform material is compression molded into a portion of the pre-fabricated finishing ring; Figure 7 illustrates a fragmentary cross-sectional view of a portion of the compression molding apparatus of Figures dA and dB and a cross-sectional view of the resulting preform assembly, wherein the preform assembly has been retracted and is the compression core pin; and Figure '8 illustrates an enlarged cross-sectional view "of the preform assembly of Figure 7, taken from the circle" 8 thereof.

DETAILED DESCRIPTION D? THE INVENTION Figure 1 illustrates a preform assembly 20 in accordance with a currently preferred embodiment of the invention - comprising a preform 22 and a separate finishing ring 24 secured thereon. The preform 22 can be injection molded, but preferably is prod by compression molding as will be discussed in more detail later. The preform 22 is composed of any suitable plastic material such as monolayer polyethylene terephthalate (PET) or the like, or PET of multiple layers or the like in which the PET matrix layers, for example, are alternated with one or more layers of a barrier resin material such as ethylene vinyl alcohol < EVOH), nylon or similar. The finishing ring • 24 is injection-molded or -compression or similar, and is composed of any desired material such as PET, post-consumer resin (PCR), process re-trituration (REG), polypropylene - ( PP), polyethylene (PP) ', polyethylene naphthalate. { PEN), or similar. Preferably, however, the finishing ring 24 is composed of a material different from that of the preform 22, such as amorphous PET for the preform 5 and crystallized PET for the finishing ring -2. Figure 2 illustrates a container assembly 12O that is blow molded from the preform assembly 20 of Figure 1 in accordance with another currently preferred embodiment of the present invention, and includes the finished ring 24 secured to a container 122. of one - that is in all significant respects identical to that of the preform assembly 20 of which the container assembly 120 is blow molded. Consequently, such security details will not be repeated for this modality. In Figure 1, the preform 22 includes a closed lower end 26 and extends upward thereof in the form of a body -28 terminating in a neck cylindrical 30 - which is integrally molded - with "body 26. (Directional words such as" upper "and" lower "are used by way of description and not limitation with respect to direct orientation of preform assemblies and illustrated components in the figures, directional words such as "radial" and "circumferential" are used by way of description and not limitation with respect to the axis of the preform neck or end ring when appropriate). As also shown in figures 3-5, the finishing ring 24 is circumferentially continuous and includes an annular cylindrical wall 32 having one or more external threads or thread segments 34. In the preferred embodiment illustrated in the figures, a circumferential ridge 3d extends around the outer surface of the wall 32 below the threads 34 to cooperate with a tamper indicating mechanism in a closure or shown) that is secured to the finished portion of the final container. A capping or support projection 3-8 s extends radially outwardly from the lower end of the wall 32, giving the finishing ring -24 a generally L-shaped lateral cross section in the illustrated embodiments of the invention. As best shown in Figure S, the finishing ring 24 includes a cylindrical internal surface 40 and a tapered inner surface 42 extended between the upper and lower ends 4, 4d. The annular grooves 48 are provided-on the tapered inner surface 42, as will be described further with reference to the subsequent FIGS. Refer now, in general, to Figures 6A-8, a compression molding apparatus 50 is illustrated for use in accordance with an exemplary method of the present invention. In Figure 6A, the apparatus SO includes a pin core 52 positioned above a compression mold 54. The compression mold 54 includes a closed lower end 56, a body portion 58, and a partial finishing portion 60 which together define a mold cavity 62. The apparatus 50 occupies a open position in Figure 6A, in which a preform material load 64 is inserted into the compression mold cavity 62 and the pre-fabricated finishing ring 24 is placed on the compression core pin 52, as shown in FIG. The charge d4 is soft or fused, and whereby the lower end of the mold cavity 62 is formed and filled. The core pin 52, with the finishing ring 24 mounted thereon, and the mold 54 are placed in vertical alignment. shown in Figure 6B, the core pin 52 and the finishing ring 24 then move in the mold 54 to overmold the load 64 partially over the finishing ring 24. The term "eobremoide" is a term of the art and, as used herein, means molding a component from a soft or molten state to another component in a solid or finished state. The charge of molten preform material d4 flows in an upward or forward direction between the core pin 52 and mold 54. Co or a result, the preform 22 is formed including the closed bottom end 2d, the body 28 and the neck 30 More significantly, however, the preform assembly 20 is formed from the overmolding of the preform 22 to the finishing ring 24. Then, and as shown in Figure 7, the core pin 52 retracts with the assembly preform 20, including the preform 22 and finishing ring -24, mounted thereto. As shown in Figure 8, the preform assembly 20 includes the preform 22 compression molded partially within a portion of the finishing ring 24. More specifically, the neck 30 of the preform 22 includes an upper portion 66 having annular projections d 8 extending in the annular grooves 48 of the finishing ring 24 to radially positively interlock or internally engage the finishing ring -24 to the preform 22. The annular grooves 48 in the finishing ring 24 can also be referred to as recesses radial or internal radial coupling devices. The radial internal coupling between the preform 22 and finishing ring 24 provides positive resistance to any axially applied force tending to separate the components 22, 24. The preform 22 also includes a tapered or tapered outer surface 70 corresponding to the tapered inner surface or conical 42 of the finishing ring 24. The tapered inner surface 42 of the finishing ring 24 is larger in diameter than the corresponding portion of the core pin 52. Accordingly, a small opening 72 is provided between the core pin 52, tapered inner surface 42 of the finishing ring 24, and a leading edge 74 of the preform 22. In terms of the preform assembly 20, the opening 72 is provided between a transition point 7d of the finishing ring 24 and the leading edge 74 of the preform 22, wherein the transition point 76 is defined by the intersection of the cylindrical or straight internal surface 40 and the tapered inner surface 42. The opening 72 is intentionally provided to accommodate within the tolerance variation of the size, volume or weight of the molten preform load. In other words, at least some opening 72 should always be present under maximum material conditions of both the preform 22 and the finishing ring 24, to ensure an appropriate fit between them without any distortion due to overpacking of the preform material inside. of the finished ring 24. The term "overpack" is a term of the art and, as used herein, refers to a condition where an excessive amount of molten polymer is compression molded and tends to lead to difficulties the ejection of the finished formed part or pieces from the compression molding apparatus. Overpacking also tends to lead to buckling of, and residual stress within, the finished part or parts. With one or more of the embodiments described above, the present invention provides a number of advantages. The present invention facilitates the production of preform assemblies and container assemblies wherein a finishing ring is composed of a material different from that of a preform or container when the terminating ring is radially coupled internally. Likewise, the present invention facilitates the application of finishing rings of various sizes and / or materials, to a common size preform and / or container. Furthermore, the present invention makes possible a decrease in the cycle time required to produce a preform because the process restriction - forming the neck termination portion - can be subordinated to a separate parallel production process to produce only rings of termination. In the same vein, the present invention makes possible a reduction in the piece price of each preform because the mold tool can be simplified, and reduced in cost, to omit the complex osca splitting characteristics typically required for the threaded termination portion of the preform. Accordingly, preform assemblies have been described for blow molding plastic container assemblies, blow molded plastic container assemblies of such preform assemblies, and method for producing such preform assemblies and container assemblies. The present invention has been described in conjunction with the presently preferred embodiments thereof, and a number of modifications and variations have been discussed. Other modifications and variations will easily inspire people of ordinary skill in the art in view of the foregoing description. Indeed, it is proposed that the invention include all modifications and variations that fall within the scope of the appended 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 (9)

CLAIMS Having described the invention as above, the content of the following revocations is claimed as property:

1. A method for producing a preform assembly, characterized in that it comprises: providing a plastic termination ring on a core pin of a compression mold; and compression molding a plastic form on the termination ring in the mold.

2. Method according to claim 1, characterized in that it includes providing a load of preform material in the mold, and wherein at least a portion of the preform material flows between the termination ring and the core pin during the stage. of compression molding. Method according to claim 2, characterized in that the termination ring includes an internal coupling device, and wherein at least a portion of the preform material flows into the internal coupling device during the compression molding step. Method according to claim 1, characterized in that the termination ring has an internal coupling surface of greater diameter than the core pin, and wherein at least a portion of the molded preform is formed between the coupling surface and the core pin. Method according to claim 1, characterized in that an opening is provided between an internal mating surface of the finishing ring and the core pin, and wherein the opening is not completely filled during the compression molding step. Method according to claim 1, characterized in that a preform material charge is provided in the mold, and the core pin and terminating ring are moved in the mold allowing the preform material to flow into the coupling with a internal surface of the termination ring. 7. Assembly of preform produced by the method according to claim 1, characterized in that it comprises the termination ring and preform. 8. Method for producing a container assembly, characterized in that it includes blow molding the preform according to claim 1 to form a container. 9. Assembly of a container produced by the method according to claim 8, characterized in that ld comprises the termination ring and container. 1 . Preform assembly for blow molding a container assembly, characterized in that it includes: a molded plastic end ring, and a plastic preform which is compression molded to the end ring so that a portion of the neck of the preform plastic radially internally engages "the termination ring. 11. Preform assembly according to claim 10, characterized in that the termination ring has at least one radial internal coupling device formed therein, and wherein the neck portion of the plastic preform engages at least one device radial internal coupling. 12. Preform assembly according to claim 10, characterized in that the terminating ring includes an inner surface having a lower tapered surface, an upper straight surface, and a transition point therebetween, and wherein an open aperture exists between the transition point and a leading edge of the neck portion of the plastic preform. 1

3. Container assembly, characterized in that it comprises: a molded plastic termination ring, and a blow molded plastic container of a preform assembly, the preform assembly includes a preform having a neck portion molded by compression to the termination ring. 1 . Container assembly according to claim 13, characterized in that the termination ring has at least one internal radial internal coupling device, and e wherein the neck portion of the plastic container engages at least one radial internal coupling device. 15. A container assembly according to claim 14, characterized in that the terminating ring includes an inner surface having a lower tapered surface, an upper surface r-ecta, and a transition point between these, and wherein an open aperture. it exists between the transition point and a leading edge of the neck portion of the plastic container.