EXTRUDED PET PARISON, CONTAINER, AND METHOD

Abstract

An extruded PET parison includes a first extruded polymer comprising PET, and a second extruded polymer comprising PET. In embodiments, the first extruded polymer and the second extruded polymer are co-extruded, and the first extruded polymer has an intrinsic viscosity that is higher that the intrinsic viscosity of the second extruded polymer. A monolayer embodiment is also disclosed. In embodiments, a monolayer extruded PET container is comprised of bottle grade PET resin that has been solid stated and may have an IV from about 0.96 to about 1.4.

Claims

1. An extruded PET monolayer parison for forming an extrusion blow molded container, the extruded PET monolayer parison comprising: an extruded PET monolayer; wherein the extruded PET monolayer is in a solid state, the extruded PET monolayer has an intrinsic viscosity from about 0.96 to about 1.4; the extruded PET monolayer is devoid of chain extenders; and the extruded PET monolayer is not injection-stretch blow molded.

2. The extruded PET monolayer parison of claim 1, wherein the extruded PET monolayer has an intrinsic viscosity of about 1.1.

3. The extruded PET monolayer parison of claim 1, wherein the PET comprises bottle grade PET resin initially having an IV of from about 0.65 to about 0.87 that has been solid-stated to increase the IV of the PET resin.

4. A container formed from the parison of claim 1, wherein the container is extrusion blow molded from the extruded PET monolayer parison.

5. The container of claim 4, wherein the container is substantially free of striations and haze.

6. The container of claim 4, wherein the container, in addition to being devoid of chain extenders, is devoid of additives or modifiers used with chain extenders with PET resin.

7. The container of claim 4, wherein the container is devoid of chain extenders and is recyclable.

8. An extruded PET parison comprising: a first extruded polymer comprising PET; and a second extruded polymer comprising PET; wherein the first and second polymers are co-extruded, the first and second extruded polymers are in a solid state, and the first extruded polymer has an intrinsic viscosity that is higher that the intrinsic viscosity of the second extruded polymer.

9. The parison of claim 8, wherein the first extruded polymer has an intrinsic viscosity of at least 0.96.

10. The parison of claim 8, wherein the first extruded polymer has an intrinsic viscosity from about 1.0 to about 1.4.

11. The parison of claim 8, wherein the second extruded polymer has an intrinsic viscosity of less than 0.85.

12. The parison of claim 8, wherein the second extruded polymer has an intrinsic viscosity of about 0.80 to about 0.87.

13. The parison of claim 8, wherein the second extruded polymer comprises post-consumer recycled (PCR) PET or regrind PET.

14. The parison of claim 8, wherein the second extruded polymer includes a colorant.

15. The parison of claim 8, wherein the cross-sectional thickness of the first extruded polymer is at least about 0.20 of the total parison thickness.

16. The parison of claim 8, wherein the cross-sectional thickness of the second extruded polymer is less than about 0.80 of the total parison thickness.

17. The parison of claim 8, including one or more additional extruded polymer layers.

18. The parison of claim 17, wherein the one or more additional extruded polymer layers comprise recycled or reground material.

19. A container formed from the parison of claim 8.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, wherein:

[0011] FIG. 1 is a partially broken away view that generally illustrates an embodiment of a multi-layer extrusion blow molded container;

[0012] FIG. 2 is a partial sectional view that generally illustrates a wall of the molded container;

[0013] FIG. 3 is a partial sectional view of a wall of an embodiment of an intermediate article; and

[0014] FIG. 4 is a partial sectional view of a wall of another embodiment, which is associated with a monolayer article.

DETAILED DESCRIPTION

[0015] Reference will now be made in detail to embodiments of the present invention, examples of which are described herein and illustrated in the accompanying drawings. While the invention will be described in conjunction with embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims.

[0016] By way of example only, and without limitation, FIG. 1 generally shows a partially broken away view that generally illustrates an embodiment of a multi-layer extrusion-blow molded container 10. FIG. 2 depicts a partial sectional view that generally illustrates a portion of a wall (identified as portion A) of the container 10. In the illustrated embodiment, innermost three layers 12, 14, 16 may be formed in a first processing stagewhich may involve co-extrusion or multiple extrusions of materialsand may provide an intermediate article 20. In the illustrated embodiment an optional, fourth/outermost layer 18 is included. The optional outermost layer, if included, 18 may be comprised of similar or different plastic material than the other layers and, if desired, may comprise a coating. An embodiment of a wall portion of an intermediate article is generally illustrated in FIG. 3. While three layers are disclosed in connection with the intermediate article 20, and four layers are disclosed in connection with the container 10, those of skill in the art will recognize that more layers (or even less layers with respect to the intermediate article 20) may be provided and the layers may have different configurations and thicknesses (including differing thicknesses as to a given layer and relative layer-to-layer thickness variations). FIG. 4 generally illustrates an embodiment of a wall portion of a monolayer article or container. The article or container is generally comprised of a single layer (generally illustrated as layer 14).

[0017] In embodiments of the present disclosure, a method is provided in which two or more polymers are co-extruded to form a parison that can be subsequently blow into a bottle or container. In an embodiment, two separate polymers may be provided. A first polymer may comprise PET and may have a comparatively higher IVe.g., 0.96 or greater (or, for instance, from about 1.0 to about 1.4). The first polymer may, for example and without limitation, be created by solid-stating standard bottle grade PET and may be devoid of chain extenders. A second polymer may also comprise PET and may have a comparatively lower IVfor instance, less than about 0.85 (or, for example, from about 0.8 to about 0.87). The second polymer, i.e., having a comparatively lower IV, may comprise post-consumer recycled (PCR) PET and/or regrind PET. Moreover, for some embodiments, the second polymer may additionally include one or more colorants.

[0018] In an embodiment, the first polymer may be provided with an IV of, for example, about 0.97, while a second polymer may have an IV of, for example, 0.76. The layer with the comparatively higher IV can serve to handle higher melt temperatures and provide strength, and can additionally help to prevent migration.

[0019] In embodiments of a method and system, the first (higher IV) and second (lower IV) polymers may be extruded and combinede.g., via an extrusion headto form a parison having multiple (e.g., two) layers. In an embodiment, the cross-sectional thickness (along the sidewall and perpendicular to the centerline of the parison) of the higher-IV layer may be about 20% (0.20) of the total parison thickness, and the thickness of the lower-IV layer may be about 80% (0.80) of the total parison thickness. Further, depending on the desired content of the resulting bottle or container, the higher-IV layer and the lower-IV layer may be interchanged with respect to which layer is the inner co-extruded layer and which layer is the outer co-extruded layer.

[0020] Embodiments of bottles and containers produced in accordance with the present disclosure may comprise crystalline PET, may exhibit commercially acceptable clarity, and may be fully recyclable in the standard PET recycling stream (i.e., marked as No. 1).

[0021] In embodiments, an extrudable PETthat is not solid-statedmay have a composite IV of about 0.96, or less, so as to be able to extrude down. The invention is not, however, limited to equipment that extrudes in the direction of gravity, and other known techniques may be employed.

[0022] Further, the disclosed method and system may be applied to parisons formed in one co-extruded layer, or in multi-layer embodiments that have two or more extruded layers. Moreover, in embodiments, one layer may serve as a carrier layer, while the other layer(s) may impart one or more other structures or features. Such other structures or features may include the use of PCR, coloring (e.g., an outside color), or cost optimization (e.g., inclusion of a comparatively less expensive (junk) middle layer). Without limitation, in an embodiment a comparatively high-IV polymer may serve as a skeleton, while another layer may include as much as 28% or more PCR. Further, without limitation, some embodiments of resulting bottles or containers may comprise a PCR content of between about 10% to 50% by weight. In other embodiments, the PCR content may be in the nature of about 20% to 30% by weight. Moreover, if desired, a junk layer of 80% or more (even up to 100%) PCR may additionally be included. Embodiments of the present disclosure are not dependent upon chain extenders, and are not combinations of amorphous and solid state resins. That is, the extrudable polymers can be provided in a solid state condition, and are not amorphous.

[0023] A potential benefit of a dual layer is the ability to utilize a carrier resin. It is also possible to color one or both layers to provide different visual effects, whether the layer or layers are colored alone or in various combinations. Further, if permeation is a potential issue, one or more barrier layers may be employed in connection with one or more layers of the parison/article.

[0024] Parisons associated with the disclosed concept may be processed utilizing various forms of known processing techniques and equipment. For some embodiments, a shuttle-type system may be used. With shuttle-type equipment a head with multiple outlets may provide a parison at a common spot and a mold or molds can be moved, or shuttled, in position under the parison. Such a system may work well if space is an issue and/or if production will be more on demand with less concerns about high capacity and speed. Alternatively, various known rotary or wheel extrusion techniques may be employed where a more continuous process, with potentially higher speed and output, is desirable. In embodiments, wheel extrusion devices and apparatus may, as desired, be configured to extrude in various directionsfor example, upwards or, perhaps more desirably for some applications, downwards.

[0025] Another embodiment of the present disclosure comprises a monolayer extruded PET container made from standard bottle grade PET resin that has been solid-stated. Standard bottle grade PET resin may have an IV of from about 0.65 to about 0.87. With embodiments of the instant disclosure, such PET resin may be solid-stated to increase its IV to from about 0.96 to about 1.4, and for some embodiments, about 1.1. Such resin may be devoid of chain extenders or other similar additives or modifiers. Extrusion blow molding of such resin, for example in connection with a downward-extruding wheel process, can produce a recyclable (e.g., #1 marked) PET container with good clarity and material distribution (which can result in improved container strength and performance). As referenced herein good clarity may describe containers that are substantially free of striations and/or haze. Containers produced in accordance with the teachings of this disclosure can result in containers that are well suited to withstand drop tests, including conventional three-foot drop tests (which may be chilled or unchilled tests). That is, with limited testing, a significant number (e.g., greater that 50%) of the tested containers pass a three-foot drop test. In embodiments, in connection with the EBM processing of such resin, it can be desirable to maintain generally consistent mold temperatures.

[0026] The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and various modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to explain the principles of the invention and its practical application, to thereby enable others skilled in the art to utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.