Method for forming a Container from bi-axially Orientable Plastics Material and having an Integral Handle

Abstract

A method of forming a container from bi-axially orientable plastics material and having an integral handle with the steps of forming a preform having a neck portion and an expandable portion below the neck portion, with the neck portion including a locating ring above the expandable portion and a handle molded to the non expandable at one end and molded to the expandle portion at the other end. Where the molded-in handle is the approximate length of the handle of the finished container. The unblown preform of orientable plastics is inserted into a blow molder and thereafter stretched by a stretch rod. During the stretch process the handle on the preform unbends rather than stretching to form the approximate shape of the handle in the finished container. The blow mold then closes on the stretched preform thus capturing the handle. Blow gas is then injected into the interior.

Description

BACKGROUND OF INVENTION

1. Field of Invention

The present invention relates to a method for forming a container from bi-axially orientable plastics material and having an integral handle and in more particular using PET or like thermoplastics material.

2. Description of Prior Art

There is a continuous demand, particularly in the food and beverage industry, for articles, such as bottles, buckets, pitchers, etc., made of clear, tough plastic because they are relatively inexpensive, easy to use, generally non-breakable and serve as good substitutes for glass. It is oftentimes desirable that such articles have handles to as good substitutes for glass. It is oftentimes desirable that such articles have handles to aid in their use, particularly large bottles.

However, it is generally understood that PET lacks sufficient hot melt strength to be extrusion blow molded and it work hardens thereby preventing it from entering shallow areas or forming sharp corners of a mold which form an integral handle. As a result, integrally molded handles on PET bottles have been susceptible to breakage, especially when molded in bottles of larger sizes. The bottle industry has sought an integral-handled PET bottle since PET was first commercially available in 1977. Eastman, DuPont, and other PET resin manufacturers developed a modified PET, called E-PET, that allowed the composition to be extrusion blow molded to form bottles with handles for detergents, milk, etc. However, these bottles were not properly oriented and shattered when drop tested. Also, E-PET was costly and efficiencies in production could not be utilized to reduce the bottles' cost.

Thus, when PET was used and handles were desired, it had been the practice to attach the handle to the PET article in a separate operation, such as by ultrasonic fusion, after the blow molded PET article had been formed in, and removed from, the blow mold. U.S. Pat. No. 4,727,997 discloses a method and apparatus for producing a PET bottle with a PET handle. In a first step, a parison is blow molded in a blow mold which has inwardly extending circumferential ridges to produce a blown bottle with article-encircling grooves therein. In a second step, the blow molded bottle is transferred to a second grip forming mold, which has circumferential grooves therein, and a handle is injection molded onto the bottle.

Another approach has been to injection mold a thermoplastic handle in a separate operation from the blow molding of the container, and then to snap the separately molded handle over the neck or finish of the blown PET bottle. In accordance with a still further proposal, the separately molded handle is inserted into the blow mold and the bottle is blown over, or into, the handle. This rests in a bottle that has a carrying handle or a two handed pour bottle.

Others have previously attempted to overcome the problems associated with forming PET bottles with durable integral handles. U.S. Pat. Nos. 4,992,230, 4,993,931 and 5,057,266 all disclose a method and apparatus for making a hollow blow molded PET article with an integral external projection such as a handle. The method includes blow molding the hollow article and then injection molding the integral projection thereon. The apparatus includes a combination mold having separate and independent blow mold and injection mold cavities which communicate at an interface therebetween. In essence, in the method and apparatus of that invention, a PET preform is inserted into a combination blow mold and injection mold wherein the blow mold cavity defines article (bottle) to be blown and the injection mold cavity defines the handle. The blow mold and injection mold cavities are in communication with each other at a location defining the area where the handle is to extend from the container. After insertion into the blow mold, the preform is injected with blow gas from a gas nozzle to conform the preform to the blow mold cavity thereby forming the hollow blow molded bottle. While the pressure of the blow gas holds the preform in conformity with the blow mold cavity, and prior to exhausting the blow gas, molten PET is injected under pressure into the injection mold cavity to form the integral handle and bond it to the blown preform bottle at the point where the injection mold cavity communicates with the blow mold cavity. The combination mold is then opened and the finished bottle is removed.

Another attempt to solve the handle prolem U.S. Pat. No. 6,733,716 whereby a PET bottle is stretch blown and the heated mold parts close on the blown bottle and try to form a handle. With this method material must then be trimmed out causing wasted and decrease production rates.

None of the above practices, however, has been entirely satisfactory in making PET bottles with integral handles since they add steps to the fabrication process, utilize extra materials, and employ complicated molds. Furthermore, other known methods requiring ultrasonic bonding equipment or multiple separate molds are unduly time-consuming, unnecessarily expensive and still do not overcome the handle breakage problem seen in larger bottles or containers.

There is still room for improvement in the art.

SUMMARY OF THE INVENTION

The current invention is a method of forming a container from bi-axially orientable plastics material and having an integral handle with the method of 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 handle molded to the non expandable at one end and molded to the expandle portion at the other end. The molded-in handle is the approximate length of the handle of the finished container. The unblown preform of orientable plastics is inserted into a blow molder and thereafter stretched by a stretch rod. During the stretch process the handle on the preform unbends rather than stretching to form the approximate shape of the handle in the finished container. The blow mold then closes on the stetched preform thus capturing the handle. Blow gas is then injected into the interior of the preform. The blow gas causes the handle portion of mold to move to the shape of the finished container while simultaneously blowing the finished container. After the preform is blown into the shape of the bottle in the mold, blow gas is discharged from the stretch rod.

BRIEF DESCRIPTION OF DRAWINGS

Without restricting the full scope of this invention, the preferred form of this invention is illustrated in the following drawings:

FIG. 1 a shows the preform prior to being blown;

FIG. 1 b shows a side view of the preform prior to being blown;

FIG. 1 c shows a cross section of the preform prior to being blown;

FIG. 1 d shows a cross section of the handle;

FIG. 2 shows a schematic of the preform in the stretched position with an adjustable stretch rod in the blowmold with the moveable handle piece; and

FIG. 3 shows a schematic of the blown bottle in the mold with the moveable handle piece shifted to it final position.

DETAILED DESCRIPTION

The following description is demonstrative in nature and is not intended to limit the scope of the invention or its application of uses.

There are a number of significant design features and improvements incorporated within the invention.

The current invention is a method of forming a container 100 from bi-axially orientable plastics material and having an integral handle 10 with the method of forming from a preform 1.

According to one aspect of the invention, there is provided a preform 1 for a container 100 comprised of orientable thermoplastic material and arranged so that the resultant blown container 100 will include a handle 10 with the preform 1 comprising a molded structure having a neck portion 20 and an expandable portion below the neck as shown in FIGS. 1a and 1b. The preform 1 will have an opening 30 and cavity 40 as shown in the cross section view of FIG. 1c with a handle cross section 12.

The neck 20 typically includes a locating ring above the expandable portion as shown in a cross section in FIG. 1d. The preform has an integrally molded solid handle attached at 2 points along the vertical axis. The first point of attachment can be either at the non expandable portion of the preform or the expandable portion of the preform. The second point of attachment is at the expandable portion of the preform. The approximate length of the desired handle in the finished container 100 determines the length of the handle. Therefore the shape of the attached handle can be of various geometries to accommodate the desired handle length.

During the blow molding operation the preform 1 is oriented in a manner to provide sufficient heat behind the handle 10 while not overheating the handle 10. On the final station prior to blowing the container 100 the preform 1 is oriented so that the handle 10 is in the proper alignment with mold 70. In a typical injection stretch process the mold 70 would close, the stretch rod 60 would be extended and the blow air would create the container. Unlike typical injection stretch blown processes when the preforml arrives at the blowing station the neck 20 of the preform 1 is externally secured. The modified stretch rod 60 is extended causing the preform to stretch.

The modified stretch rod 60 may have an adjustment portion 65 to adjust the size of the rod 60.

When the preform 1 stretches, the attachment points of the handle 10 become separated to the distance of the blown container. The handle 20 itself does not stretch rather uncoils. This causes a sufficient gap between the preform 1 and the handle 20. The mold then closes and the handle 20 is then trapped in the handle pocket 80 of the mold. The handle pocket 80 of the mold 70 is allowed to move to its final location by means of the blow air while the container 100 is blown. The movable mold segments within the blow mold cavity may be unitary segments or may themselves consist of multiple parts. When the mold 70 is opened the handle pocket 80 is retracted resulting in an injection stretch blown container with an integral handle attached at 2 points.

In an alternate version of the preform, the preform handle could be achieved by mechanical means by physically attaching the handle to the preform outside the injection molding process or by coinjecting the handle on the preform.

In an alternate version of the preform, the preform could be molded with a handle that is shorter than the finished handle. The handle 10 itself could be stretched to the desired length with the stretch rod 60.

In an alternate form of this invention utilizing the handled preform 1 the sequence of the injection stretch operations could be modified. When the oriented preform is sequenced into the molding station the molds 70 would close, the stretch rod 60 would be extended. However prior to blowing the container 100, the handle pockets in the mold 70 would extend to capture the handle 20. When the container 100 is blown the handle pocket would be allowed to move to the finished container requirements. The movable mold segments within the blow mold cavity may be unitary segments or may themselves consist of multiple parts.

Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible. Therefore, the point and scope of the appended claims should not be limited to the description of the preferred versions contained herein.

As to a further discussion of the manner of usage and operation of the present invention, the same should be apparent from the above description. Accordingly, no further discussion relating to the manner of usage and operation will be provided.

Claims

1. A preform for a container comprised of orientable thermoplastic material and arranged so that the resultant blown container will include a handle; said preform comprising a molded structure having a neck portion and an expandable portion below the neck, said neck typically includes a locating ring above the expandable portion, where the preform has an integrally molded solid handle attached at 2 points along the vertical axis with the first point of attachment at the non expandable portion of the preform or the expandable portion of the perform, where the second point of attachment is at the expandable portion of the perform with the approximate length of the desired handle in the finished container determines the length of the handle therefore the shape of the attached handle can be of various geometries to accommodate the desired handle length.

2. The preform of claim 1, where the preform is formed by an injection process including two separate, first and second, points of injection.

3. The preform of claim 2, wherein the first point of injection injects non-recycled PET or like thermoplastics material to form a portion of the preform.

4. The preform of claim 3, wherein the second point of injection injects PET or like thermoplastics material incorporating at least a portion of recycled material.

5. The preform of claim 2, wherein the first point of injection is for the formation of that part of the preform which will be stretched during a stretch blow moulding operation on the preform.

6. The preform of claim 5, wherein said second point of injection is for the formation of those parts of said preform which will remain unexpanded or substantially unexpanded in a stretch blow moulding operation on said preform.

7. The preform of claim 1, wherein the preform includes more than one wall profile.

8. The preform of claim 1, wherein said preform has a first wall profile closest to its neck followed by a second wall profile immediately there below and separated therefrom by a first transition zone.

9. The preform of claim 1, wherein said preform has a first wall profile closest to its neck followed by a second wall profile immediately there below and separated therefrom by a first transition zone, and further wherein the said preform further includes a third wall profile immediately below said second wall profile and separated therefrom by a second transition zone.

10. A method of making a hollow blow molded article having a handle attached at 2 points from the preform of claim 1 extending from the exterior wall thereof comprising the steps of: (a) inserting an unblown preform of thermoplastic polymer into a blow mold having a hollow article-defining blow mold cavity and movable mold segments; (b) orienting a preform in a manner to provide sufficient heat behind the handle while not overheating the handle; (c) reorienting the preform in the final station prior to blowing the container so that the handle is in the proper alignment with mold; (d) securing the neck of the preform at the blow station; (e) Extending a modified stretch rod causing the preform to stretch so when the preform stretches, the attachment points of the handle become separated to the distance of the blown container, where the handle itself does not stretch rather uncoils causing a sufficient gap between the preform and the handle; (f) Closing the mold causing the handle to be trapped by the handle pocket of the mold; (g) inflating the container by means of the blow air causing the handle pocket of the mold to move to the final destination of the finished container; (h) opening said blow mold; and (i) removing the blow molded article having a handled connected at two points from said blow mold allowing the handle pocket to retract for the next container to be blown.

11. The method of claim 10 having a stretch rod where said stretch rod make contact with the preform during stretching at 2 discreet points. First point being at the bottom of the preform and the second point being at the inside diameter of the preform where the handle is attached at the inflatable portion of the preform.

12. The method of claim 10 having a movable handle pocket in the mold where said handle pocket may be unitary segments or may themselves consist of multiple parts.