AU720887B2 - Container with integral handle, preform and method of manufacture - Google Patents

Description

WO 96/33063 PCT/AU96/00232 CONTAINER WITH INTEGRAL HANDLE. PREFORM AND METHOD OF MANUFACTURE

INTRODUCTION

This invention relates to a preform from which a container such as a PET container can be blown and more particularly to a preform and a container formed therefrom that has an integral handle.

BACKGROUND OF THE INVENTION Attempts have been made to incorporate integral handles in PET and like injection blow moulded containers for example see US 4,629,598 to Thompson, assigned to Tri- Tech Systems International, Inc. The parison from which the handled bottles of US 4,629,598 are produced is illustrated in Fig. 1. To date, however, attempts to produce a practical, mass produced version of this arrangement have been unsuccessful. Instead, the best that appears to have been done in commercial practice is an arrangement whereby the blown containers are arranged to accept a clip on or snap on handle in a separate production step after the container itself is formed. See for example W082/02371 and W082/02370, both to Thompson.

Injection-stretch-blow moulding is a process in which the parison is stretched both axially and radially, resulting in biaxial orientation.

Biaxial orientation provides increased tensile strength (top load), less permeation due to tighter WO 96/33063 PCT/AU96/00232 -2alignment of the molecules, and improved drop impact, clarity, and lightweighting of the container.

Not all thermoplastics can be oriented. The major thermoplastics used are polyethylene terephthalate (PET), polyacrylonitrile (PAN), polyvinyl chloride (PVC), and polypropylene PET is by far the largest volume material, followed by PVC, PP, and PAN.

The amorphous materials, PET, with a wide range of thermoplasticity are easier to stretch-blow than the partially crystalline types such as PP. Approximate melt and stretch temperatures to yield maximum container properties are: Material Melt, Degrees C. Stretch, Degrees C.

PET 280 107 PVC 180 120 PAN 210 120 PP 240 160 There are basically two types of processes for stretch-blow moulding: 1) single-stage in which preforms are made and bottles blown on the same machine, and 2) twostage in which preforms are made on one machine and blown later on another machine.

Single-stage equipment is capable of processing PVC, PET, and PP. Once the parison is formed (either extruded or injection moulded), it passes through conditioning stations which bring it to the proper orientation temperature. The single-stage system allows the process to proceed from raw material to finished product in one machine, but since tooling cannot be easily changed, the process is best suited for dedicated applications and low volumes.

WO 96/33063 PCT/AU96/00232 -3- Oriented PVC containers most commonly are made on single-stage, extrusion-type machines. The parison is extruded on either single- or double-head units.

Temperature conditioning, stretching, and thread forming are done in a variety of ways depending on the design of the machine. Many of the processes presently in use are proprietary.

Many oriented PET containers are produced on singlestage machines. Preforms are first injection moulded, then transferred to a temperature conditioning station, then to the blow moulding operation where the preforms are stretchblown into bottles, and finally to an eject station.

With the two-stage process, processing parameters for both preform manufacturing and bottle blowing can be optimized. A processor does not have to make compromises for preform design and weight, production rates, and bottle quality as he does on single-stage equipment. He can either make or buy preforms. And if he chooses to make them, he can do so in one or more locations suitable to his market. Both high-output machinesand low output machines are available. Two stage extrusion-type machines generally are used to make oriented PP bottles. In a typical process, preforms are re-extruded, cooled, cut to length, reheated, stretched while the neck finish is being trimmed, and ejected. The two-stage process is the lowest-cost method to produce oriented PET containers. The two-stage process, which permits injection moulding of the preform and then shipping to blow moulding locations, has allowed companies to become preform producers and to sell to blow moulding producers. Thus companies that wish to enter the market with oriented PET containers can minimise their capital requirements. Two-stage stretch-blow moulding also is being used for production of oriented PVC containers.

Preform design and its relationship to the final container remains the most critical factor. The proper stretch ratios in the axial and hoop directions must be met if the container is to properly package its intended product.

4 Material Stretch Ratios Orientation Temp.Deg.F PET 16/1 195-240 PVC 7/1 210-240 PAN 9/1 220-260 PP 6/1 260-280 It is an object of the present invention to produce a practical, readily implementable injection, stretch blow moulded container made from an orientable thermoplastics material incorporating a handle which is formed during and as part of the said injection, stretch blow moulding operation.

SUMMARY OF THE INVENTION In its broadest form the invention concerns a container comprised of biaxially orientable thermoplastic material manufactured from a two stage injection stretch blow moulding process; said two stage process comprising a 9e first stage in which a preform is manufactured and a second stage in which said preform is reheated and biaxially stretched to form said container; said container including a graspable handle affixed at at least a first point of connection and a second point of connection to said container so as to form an enclosed area between said handle and said container and through which at least two fingers of a human hand can pass; and wherein said first point of connection comprises an integral connection between the handle and the container and is formed in said first stage of said two stage process; said container further including a locating ring at a neck portion thereof; said container further including a first nonexpanding region immediately below said locating ring; age 4 Sent By: wallington-dummer; 61 2 96384793; 19-Apr-uu 3:38PM; -4A said first non-expanding region incorporating at least a portion of said first point of connection; said container further including a second non-expanding region below said first non-expanding region- Further preferred and/or optional features of the invention are: The container wherein said first non-expanding region is formed so as to be slightly raised from that portion of said container which is fully biaxially oriented during said second stage of said two stage process.

The container wherein said second non-expanding region *:is not differentiated from that portion of said container which is fully biaxially oriented during said second stage of said two stage process.

Soo 0the container wherein minor expansion of said second non-expanding region takes place during said second stage of said two stage process.

*500 The container wherein said handle includes a first rib integrally moulded with and extending from said locating ring.

see* The container wherein said handle includes a second rib integrally moulded with and extending from said second :non-expanding region.

oil The container which further includes a rib connector integrally moulded with and extending from said first nonexpanding region and forming a continuous connection between said first rib and said second rib throughout the length of said handle.

The container wherein said second non-expanding region forms part of a temperature transition zone.

age 4 19/04 '00 WED 16:25 [TX/RX NO 8448] 4B The container wherein said first non-expanding region forms part of a temperature transition zone.

The container of wherein deformation of said temperature transition zone takes place during a stretch blow moulding process.

The container of wherein material is injected at different locations during formation of said preform during said first stage of said two stage process whereby said container can be composed from more than one type of material.

The container wherein during said first stage of said two stage process an inner wall and outer wall of said preform is formed, said inner wall made from a different material from said outer wall.

The present invention is described with reference to closely related aspects, such as a preform, a parison, a S method of forming a container, and such like, which are not S to be regarded as limiting the present invention, but provide supporting description.

For example, there is described a preform for a container comprised of orientable thermoplastic material and arranged so that the resultant blown container will include a handle or like support structure; said preform comprising a moulded structure having a neck portion and an expandable portion below the neck, said neck including a locating ring above the expandable portion and a solid stem of orientable thermoplastics material projecting from the locating ring and moulded integrally therewith which when the container is formed constitutes the handle.

Preferably said stem projects from said locating ring and from a temperature transition zone located immediately below said ring.

4C Also for example there is described a method of forming a container having an integral handle; s aid method comprising: forming a preform having a neck portion and an expandable portion below the neck portion, said neck portion including a locating ring above the expandable portion and a solid stem of orientable thermoplastics material projecting from the locating ring and moulded integrally therewith, and performing a blow moulding operation on said preform to expand the expandable portion to form the body of the container.

Preferably said stem projects from said locating ring and from a temperature transition zone located immediately below said ring.

In a preferred form, the neck portion and integral handle are subjected to a crystallisation step.

Preferably, the blow moulding operation includes supporting the stem whilst the preform is blown in a manner whereby at least a portion of the external side of the tube expands to encircle at least a lower portion of the stem so as to form an enclosed grip portion between the external side and the solid stem.

It is preferred that the enclosed grip portion allows at least two fingers of the adult human hand to pass therethrough.

The stem may be formed so as to have an I-shaped cross-section at least throughout that portion of the stem where it projects from the external side of said tube. The handle may be curved to provide additional strength.

In a further broad form there is provided a parison for an injection stretch blow moulding process, said 5 parison formed by an injection process including two separate points of injection.

Preferably a first point of injection permits injection of non-recycled PET or like thermoplastics material. Preferably a second point of injection permits injection of PET or like thermoplastics material incorporating at least a portion of recycled material.

Preferably said first point of injection is for the formation of that part of the parison which will be stretched during a stretch blow moulding operation on the parison. Preferably said second point of injection is for the formation of those parts of said parison which will remain unexpanded or substantially unexpanded in a stretch blow moulding operation on said parison.

In regard to the present invention, preferably said first point of connection comprises an integral connection between the handle and the container and is formed in said first step of said two step operation.

.4 Preferably said second point of connection is formed S. during said second step of said two step operation.

Preferably said handle at said second point of interconnection includes a bulbous portion adapted to be at least partially enfolded by a portion of said container as it is blown during said second step of said two step operation whereby a mechanically interlocked connection is o formed at said second point of connection of said handle to said container.

In particular preferred forms said bulbous portion comprises one of an upwardly extending hook, a downwardly extending hook, a bulb or a combination of one or more thereof.

6 BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present invention will now be described by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a side view of a prior art parison, Fig. 2 is a side view of a parison incorporating features according to embodiments of the present invention, Fig. 3 is a partial side elevational view of a blow moulded PET container formed from a preform according to one embodiment of the invention.

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WO 96/33063 PCT/AU96/00232 -7- Fig. 4 illustrates the steps of formation of a parison according to another embodiment of the invention.

Fig. 5A is a side view of a preform according to a further embodiment of the invention; Fig. 5B is a side view of a container formed from the preform of Fig. SA.

Fig. 6 is a side view of a die in open position for manufacture of a preform; Fig. 7 is the die of Fig. 6 in closed position and Fig. 8 is a side view of the die of Figs. 6 and 7 showing the stem of the preform located therein.

DETAILED DESCRIPTION OF THE DRAWINGS A container 10 according to an embodiment of the invention is shown in Fig. 3. It includes a neck 11 and an expanded portion 12.

The neck 11 has a threaded portion 13 and a locating ring 14. Moulded integrally with the ring 14 is a stem having a first portion 15a extending outwardly from the ring 14 and a second portion 15b so inclined to the first portion 15a that it is nearly parallel to a vertical axis of the container 10. In this instance, the first portion subtends an angle of slightly more than 450 to the wall and the second portion subtends an angle of about 200 to the wall The particular shape of the stem 15 is selected so that when formed as a handle it may be grasped by fingers of the human hand.

The stem 15 terminates in a stem end 16 which faces generally downwardly in the general direction of closed end of the container In this instance, the stem 15 is of I-shaped crosssection to combat unwanted effects arising at or near junction 17 of stem 15 with the ring 14 following a blowing operation on the preform WO 96/33063 PCT/AU96/00232 -8- These unwanted effects particularly include stress effects and air inclusions resulting from non-uniform cooling through preform volumes of differing cross-section.

In this embodiment of the invention, the preform is made from PET and is prepared utilizing a heated mould.

In order to produce the container 10, the parison or preform 26 (see Fig. 2) according to an embodiment of the invention can be placed in a blow moulding machine (not shown) and blow moulded according to bi-axial orientation blow moulding techniques with the neck 11 being held in a mould in such a way as not to expand. Initially, the expandable portion of the preform below the neck can be mechanically stretched downwardly to the bottom of the mould and then the bulk of the preform can be blown outwardly by application of compressed air to the extent that a support portion 18 is formed around the stem end 16 such that an enclosed area 19 is formed between wall 20 of the container 10 and the stem 15 in the process of the formation by blow moulding of container In a particular preferred form of the invention, the enclosed area 19 is of sufficient cross-sectional area to allow at least two fingers of a human hand to be inserted therethrough and to grasp handle 15 so as to support the container The blow moulding operation is carried out in such a way so as to provide a bottle or container having optimum strength by achieving biaxial orientation of the molecules of the preferred PET material as well as improved barrier properties to reduce oxidation.

In accordance with an embodiment of the invention, the neck 11 and handle 15 can be crystallised by over-heating those parts of the preform. The crystallisation of the handle increases its rigidity which assists orientation of the preform and permits the use of less material.

Crystallisation of the neck and handle can be carried out by running hot oil over the neck and handle, applying an open flame or by blowing hot air.

WO 96/33063 PCT/AU96/00232 -9- The location of the handle 15 on the ring 14 ensures that there is minimum interference to the blow moulding process applied to the remainder of the preform. Either a one stage or two stage process can be used.

Detailed Description of Further Embodiments Fig. 1 illustrates the prior art preform or parison 21 of US 4,629,598. The concept of this prior art disclosure is to form a handle portion 23 from the locating ring of non-expandable portion 22 of the parison 21.

With reference to Fig. 2 and with reference to the detailed description of the preferred embodiment this arrangement of Fig. 1 is modified according to the present invention in a number of respects.

Insets 2A, 2B and 2C show bulbous portions 27 forming part of stem end 16 in the shape, respectively of a downwardly extending hook 24a, a bulb 24b and an upwardly extending hook 24c.

These portions have in common a shape which is adapted to engage mechanically with a blown portion of the container 10 which is adapted to envelop the bulbous portion 27.

The process by which the second stage blow of the expandable portion 12 of parison 26 is effected so as to envelope the bulbous portion 27 of stem end 16 is a stretch blow, biaxial orientation process.

With reference to Fig. 4 a particular method of manufacture of the parison 26 according to another embodiment of the invention is illustrated. It includes a two stage process for the formation of the parison by an injection moulding process. In Stage 1 a first injection mould inlet 28 permits entry of plastics material for the formation of the expanded portion 12 of the parison 26 (expanded in the blow moulding stage of container formation, with reference to Fig. 3).

In a second stage of the injection moulding process for the formation of parison 26 a second injection mould WO 96/33063 PCT/AU96/00232 inlet 29 permits entry of plastics material for the formation of the non-expandable portion 25 of parison 26.

The two stage injection arrangement is such that different plastics materials may be injected through first injection mould inlet 28 and second injection mould inlet 29.

In a particular preferred form the plastics material injected in first injection mould inlet 28 is non-recycled or substantially non-recycled plastics material whilst the plastics material injected into second injection mould inlet 29 is recycled or at least partially recycled plastics material.

This arrangement permits controlled use of proportions of recycled and non-recycled plastics material in order to achieve optimum economics in the construction of parison 26.

In a modification of this arrangement the Stage 2 step can include the production of two walls in the nonexpandable portion 25 comprising inner wall 51 and outer wall 52. Inner wall 51 is made from virgin or noncontaminated PET material and acts as an insulation barrier with respect to wall 52 which can be made from recycled material 52. This dual wall arrangement can be produced by use of a sliding core arrangement as a modification in the die arrangement and process described with reference to Figs. 6, 7 and 8 later in this specification.

Of course the Stage 1 and Stage 2 steps of Fig. 4 can be interchanged in order.

A parison and resulting container according to a further embodiment of the invention are illustrated in Figs. 5A and B respectively. Like parts are numbered as for previous embodiments.

In this embodiment the parison 21 includes a locating ring 14 immediately below which is a first non-expanding region 30 and a second non-expanding region 31. The first non-expanding region 30 may itself be formed so as to be slightly raised or otherwise differentiated from the WO 96/33063 PCr/AU96/00232 -llexpandable portion of parison 21. Second non-expanding region 31 may not be differentiated from the expandable portion of parison 21 but, in use, the blowing operation will be such as to ensure that the second non-expanding region 31 is not expanded in the blowing process.

In this case the stem 15 includes a first rib 32 integrally moulded with and extending from locating ring 14. The stem 15 also includes second rib 33 integrally moulded with and extending from second non-expanding region 31. Stem 15 further includes a rib connector 34 integrally moulded with and extending from first non-expanding region and forming a continuous connection between first rib 32 and second rib 33 throughout the length of stem The parison 36 of Fig. 5A is then blown in the manner previously described to form the volume 35 of container 37 illustrated in Fig. 5B. The neck portion including stem ring 14, first non-expanding region 30 and second nonexpanding region 31 remain unexpanded whilst the expandable portion 36 of parison 36 is biaxially stretched to form the major volume 35 of container 37. The stem end 16 may include the bulbous portions according to the previously described embodiments for connection to container 37 or, either alternatively or in addition can include the application of an adhesive material whereby a chemical bond is formed between stem end 16 and the wall of container 37 by the use of a chemical intermediary.

In a modification of the embodiments of Fig. 5A and Fig. 5B first non-expanding region 30 and second nonexpanding region 31 can form part of a single non-expanding region.

In yet a further modification second non-expanding region 31 can be located in the temperature transition zone of the container and wherein minor expansion during the blow moulding step may take place.

In yet a further modification both first non-expanding region 30 and second non-expanding region 31 may be located in the temperature transition zone immediately below the WO 96/33063 PCT/AU96/00232 -12locating ring 14 and, again, minor expansion of these regions may take place during blowing.

With respect to the last two variations described advantage is taken of the observation that expansion at the temperature transition zone can be limited by appropriate mould design and process control whereby unwanted distortion effects caused by the rigid interconnection of this temperature transition zone 30, 31 via second rib 33 and rib connector 34 to ring 14 (or other non-expanding portion of the neck 11) can be controlled.

In use preforms and containers blown therefrom can be manufactured as follows: A preform is formed from orientable thermoplastics material, preferably PET or like material in an injection moulding process. Slidable dies are illustrated in Figs.

6, 7 and 8 and include a sliding core 40, sliding blocks 41, body 42, base 43, push block 44 and splits holder Fig. 6 illustrates the die in open position, Fig. 7 illustrates the die in closed position and Fig. 8 illustrates a side view showing accommodation of the stem 14.

The completed preforms in a second and preferably separate step are subsequently passed to a stretch blow mould machine where the preforms are first reheated to the appropriate transition temperature (refer introduction).

The non-expandable portion of the preform including locating ring 14 and stem 15 are shielded substantially from the reheat process by appropriate guarding. In most instances there is likely to be a temperature transition zone in the region 30, 31 described with reference to Figs.

The reheated preform is then placed in a mould and biaxially stretched and the expandable portion blown to full size utilising processes known in the art. During this process the preform is supported at neck 14 and may also be supported at stem 15. Stem 15 does not take part in the blow process although its stem end 16 may be WO 96/33063 PCT/AU96/00232 -13partially enveloped by an external wall of the blown container.

The above describes only some embodiments of the present invention and modifications obvious to those skilled in the art can be made thereto without departing from the scope and spirit of the present invention.

INDUSTRIAL APPLICABILITY Embodiments of the invention are applicable to the manufacture of containers made from orientable thermoplastics material and incorporating a handle or like grasping fixture as an integral component of the container.

Claims (1)

19-Apr-00 3:36PM; Page 14 The claims defining the invention are as follows: 1. A container comprised of biaxially orientable thermoplastic material manufactured from a two stage injection stretch blow moulding process; said two stage process comprising a first stage in which a preform is manufactured and a second stage in which said preform is reheated and biaxially stretched to :0.:form said container; said container including a S graspable handle affixed at at least a first point of connection and a second point of connection to said container so as to form an enclosed area between said handle and said container and through which at least two fingers of a human hand can pass; and wherein said first point of connection comprises an integral connection between the handle and the container and is formed in said first stage of Said two stage process; 0 said container further including a locating ring at a :00 neck portion thereof; said container further including S a first non-expandinlg region immediately below said locating ring; said first non-expanding region incorporating at least a portion of said first point of connection; said container further including a second non-expanding region below said first nlon- expanding region. 19/04 '00 WED 16:25 [TX/RX NO 84481 SentBy: wallington-dummer; 61 2 96384793; 19-Apr-00 3:36PM; Page 6 15 2. The container of claim 1 wherein said handle includes rib portions associated with said first non-expanding region and said second non-expanding region. 3. The container of claim 1 or 2 wherein said first non- expanding region is formed so as to be slightly raised from that portion of said container which is fully biaxially oriented during said second stage of said two stage process. The container of claim 2 wherein said second non- expanding region is not differentiated from that portion of said container which is fully biaxially oriented during said second stage of said two stage process. S 5. The container of claim 2 wherein minor expansion of said second non-expanding region takes place during said second stage of said two stage process. 6. The container of any one of claims 1 to 5 wherein said handle includes a first rib integrally moulded with and extending from said locating ring. 7. The container of claim 6 wherein said handle includes a second rib integrally moulded with and extending from said second non-expanding region. 8. The container of claim 7 which further includes a rib connector integrally moulded with and extending from 19/04 '00 WED 16:25 [TX/RX NO 8448] 1 16 said first non-expanding region and forming a continuous connection between said first rib and said second rib throughout the length of said handle. 9. The container of claim 2 wherein said second non- expanding region forms part of a temperature transition zone. The container of claim 9 wherein said first non- expanding region forms part of a temperature transition zone. 11. The container of claim 10 wherein deformation of said temperature transition zone takes place during a stretch blow moulding process. 12. The container of claim 1 wherein material is injected 4 q e at different locations during formation of said *s preform during said first stage of said two stage 0@ see W process whereby said container can be composed from se 1.more than one type of material. 13. The container of claim 12 wherein during said first Sq.. .S ie.. stage of said two stage process an inner wall and sees outer wall of said preform is formed, said inner wall made from a different material from said outer wall. made from a different material from said outer wall.