Monolayer Polyethylene terephthalate (PET) containers are known to have better clarity, gloss, and oxygen and scalping barrier properties compared to containers made from monolayer polyolefins such as High Density Polyethylene (HDPE) and Polypropylene (PP). In many cases, such as when the container is used to store food products such as orange juice, it is desirable for the container to have barrier properties that are conducive to, for example, maintaining the original flavor and nutrient content of the food product (e.g. preventing flavor scalping), to prevent migration of odors into and out of the container, and to prevent the product from spoiling. Many PET containers are made in an injection stretch blow process that limits bottle design and performance (e.g., no integrated handle) compared to the extrusion blow mold process typically used for polyolefins Currently, extrusion blow molding-grade polyethylene terephthalates (EPET) are known to produce monolayer plastic containers having a handle, a desirable clear and glossy appearance, and desirable barrier properties. Many polyolefin container applications do not require clarity, but would still benefit from the improved barrier and gloss properties of PET in a more cost effective package.
For container applications where clarity is important and a high oxygen barrier is required, it is known to produce co-extruded layers of PET and a high barrier polymer (e.g. polyamide resins, or EVOH) in the injection stretch blow molding process. In this process, adhesive layers are often needed to provide sufficient bonding strength between the wall layers. Many of these applications would benefit from more design and process flexibility.
A blow molded container according to particular embodiments of the invention include a co-extruded wall that comprises: (1) a first, inner surface layer comprising an extrusion blow-molding-capable grade of PET, such as: (a) copolysters of polyethylene terephthalates (EPET) (e.g., EBO62 sold by Eastman Chemical Company) and (b) glycol-modified polyethylene terephthalates (PETG); (2) a second, interior layer comprising adhesive polymer; and (3) a third layer comprising a polyolefin and part generated regrind material from one or more containers having a composition that is similar to that of the blow molded container. In particular embodiments, the second layer is disposed between the first and third layers and is adapted to bond the first layer to the third layer. In various embodiments, the third layer is an outer surface layer of the co-extruded wall.
In a particular embodiment, the blow molded container further includes a fourth layer that comprises a polyolefin; and the second and third layers are disposed between the first and fourth layers. In various embodiments, the fourth layer is an exterior surface layer of the blow molded wall.
A blow molded container according to further embodiments of the invention include a wall comprising: (1) a first, inner surface layer comprising an extrusion blow-molding-capable grade of PET; (2) a second, interior layer comprising a barrier material selected from the group consisting of polyamide resins, ethylene vinyl alcohol polymers (EVOH), and PET-compatible oxygen scavengers; and (3) a third layer comprising an extrusion blow-molding-capable grade of PET. In particular embodiments, the second layer is disposed between the first and third layers. Also, in various embodiments, the third layer is an outer surface layer of the wall.
A blow molded container according to yet another embodiment of the invention includes a co-extruded wall that includes at least one layer comprising a blend of an extrusion blow-molding-capable grade of PET and one or more materials selected from a group consisting of polyamide resins, EVOH, and PET-compatible oxygen scavengers.
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The present invention now will be described more fully with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
Containers (e.g., bottles) according to various embodiments of the invention comprise a blow molded wall that defines the container's external dimensions and separates the container's contents from the exterior environment. In particular embodiments, the wall is made by co-extruding different polymers simultaneously during the extrusion blow molding process. In particular embodiments, such polymers may include at least one extrusion blow-molding-capable grade of PET, such as: (a) a copolyster of polyethylene terephthalates (EPET) (e.g., EBO62 sold by Eastman Chemical Company); or (b) a glycol-modified polyethylene terephthalate (PETG). This extrusion blow-molding-capable grade of PET may be in separate layers and/or blends with at least one other polymer material.
Various exemplary embodiments of the invention are discussed in greater detail below in regard to
As may be understood from
The first layer 122 may optionally comprise one or more additional additives. Suitable additives include additives compatible with PETs. For example, suitable additives may include, but are not limited to, oxygen scavenger additives such as cycloolefin polymers and copolymers and unsaturated polyolefins Examples of suitable additives include those sold by BP Amoco Chemicals under the AMOSORB® name and iron oxide formulations such as those sold by Mitsubishi Gas Chemical Company under the AGELESS® name. According to one embodiment, the additives are suitable for and approved for use with foodstuffs.
In this embodiment, the second layer 124 is an interior layer (e.g., a “tie layer”) that comprises (and, in particular embodiments, consists of, and/or consists essentially of) an adhesive or tie-layer resin suitable for bonding extrusion blow-molding-capable grades of PET and polyolefins This adhesive or tie-layer resin may comprise, for example, a maleic anhydride-modified polyolefin, such as maleic anhydride-modified polyethylenes (PE), including modified medium density polyethylenes (MDPE), low density polyethylenes (LDPE) and linear low density polyethylenes (LLDPE), and maleic anhydride-modified polypropylenes (PP). Commercially available suitable adhesives include those sold by Rohm & Haas under the TYMOR™ name, those sold by Equistar Chemicals under the PLEXAR® name including PLEXAR® PX 6002 and PLEXAR® PX 3236, and those sold by Mitsui Chemicals under the ADMER® name.
In the embodiment shown in
The third layer 126 may also include an additional amount of a suitable adhesive. Suitable adhesives for the third layer 126 include the adhesives or tie-layer resins disclosed above comprising, for example, maleic anhydride-modified polyolefin. Where the third layer 126 includes regrind material, the regrind melt preferably includes a suitable adhesive, more preferably the same adhesive as was used in production of the material used as regrind. Where the third layer 126 includes adhesive and regrind, the adhesive is preferably added to the regrind melt prior to extrusion. The amount of adhesive added to the regrind melt may vary and may be adjusted to optimize a property of the third layer, such as brittleness, adhesion, or gloss. In particular embodiments, the amount of adhesive added is suitable to prevent brittleness and breakage of the container during the extrusion process and normal use of the container. The amount of adhesive added to the regrind melt is preferably about 0.5% to about 10% by weight, more preferably about 1% to about 5%, most preferably 3% to 5%, based on the weight of the regrind material.
In particular embodiments, the third layer 126 may be an outer surface layer of the container wall 110A. However, in other embodiments, the container may include other layers that are closer to the container's exterior than the third layer 126. For example, in one embodiment, the container wall includes a fourth layer adjacent the outer surface of the third layer that serves as the outer surface layer of the container wall.
As may be understood from
As may be understood from
In various embodiments, the fourth layer 138 comprises (and, in particular embodiments, consists of, and/or consists essentially of) one or more polyolefins In particular embodiments, these one or more polyolefins may be, for example, selected from a group consisting of polyethylenes and polypropylene. In particular embodiments, these one or more polyolefins may be selected from a group consisting of HDPE and polypropylene. However, in other embodiments, other suitable polyolefins may be used.
As may be understood from
The thicknesses and relative weight of the first layer 122, second layer 124, third layer 126, optional fourth layer 138, and other optional additional layers may vary based on the desired properties of the container, the relative costs of materials, capabilities of process equipment, and other variables. According to one embodiment, the first layer 122 comprises about 2% to about 10% by weight, more preferably about 2% to about 5%, and most preferably about 5%, based on the total weight of the extruded wall 110B of the container. According to another embodiment, the first layer 122 comprises about 2% to about 20% by weight, based on the total extruded wall weight of the container. According to another embodiment, the first layer 122 comprises more than 10% by weight of the container. According to one embodiment, the second layer 124 comprises about 0.2 to about 10%, more preferably about 0.5 to about 3%, based on the total weight of the extruded wall 110B of the container.
In particular embodiments, the container wall 110 is transparent. In other embodiments, the container wall 110 is substantially clear. In particular embodiments, the amount of flavor scalping is reduced relative to a similar HDPE container. In particular embodiments, the amount of gas transmission, including oxygen transmission, is reduced relative to a similar monolayer HDPE container.
In the embodiment shown in
In particular embodiments, the container wall's third layer 146 comprises (and, in particular embodiments, consists of, and/or consists essentially of) an extrusion blow-molding-capable grade of PET. In particular embodiments, the third layer 146 may be an outer surface layer of the container wall 110C. However, in other embodiments, the container may include other layers that are closer to the container's exterior than the third layer 146. For example, in one embodiment, the container wall 110C includes a fourth layer (not shown) adjacent the outer surface of the third layer 146 that serves as the outer surface layer of the container wall 110C.
As may be understood from
In alternative embodiments of the container wall discussed above in regard to
In the embodiment shown in
In particular embodiments, the container wall 110 is transparent. In other embodiments, the container wall 110 is substantially clear. In particular embodiments, the amount of flavor scalping is reduced relative to a similar HDPE container. In particular embodiments, the amount of gas transmission, including oxygen transmission, is reduced relative to a similar HDPE container. In particular embodiments, the amount of gas transmission, including oxygen transmission, is reduced relative to a similar monolayer PET container.
In various embodiments of the invention, a polymer blend is used as at least one layer in a co-extruded multi-layer container (e.g., bottle) wall structure. In particular embodiments, the wall structure consists of (or consists essentially of) this polymer blend. In particular embodiments, the polymer blend comprises (and, in particular embodiments, consists of, and/or consists essentially of) an extrusion blow-molding-capable grade of PET and one or more materials selected from a group consisting of: polyamide resin, EVOH, and PET-compatible oxygen scavengers. In particular embodiments, the polymer blend may comprise regrind from one or more of the embodiments as described above for
In various embodiments, the polymer blend may be used as a replacement for an extrusion blow-molding-capable grade of PET in any of the embodiments described herein. For example, according to one embodiment, shown in
In other embodiments, a blend of an extrusion blow-molding-capable grade of PET, EVOH and optional adhesives may be used as a replacement or partial replacement for EVOH in known multilayer processes. For example, according to one embodiment, the container may comprise a first layer comprising polypropylene, a second layer comprising a suitable adhesive, a third layer comprising a blend of an extrusion blow-molding-capable grade of PET and EVOH, a fourth layer comprising a suitable adhesive, and a fifth layer comprising polypropylene. According to another embodiment, the container may comprise a first layer comprising HDPE, a second layer comprising a suitable adhesive, a third layer comprising a blend of an extrusion blow-molding-capable grade of PET and EVOH, a fourth layer comprising a suitable adhesive, and a fifth layer comprising HDPE. In various embodiments of the invention described above, the first through fifth layers are sequential (or substantially sequential layers) with the first layer being the closest of the layers to the container's interior and the fifth layer being the closest of the layers to the container's exterior. Accordingly, in such embodiments, the second layer would be the second closest of the layers to the container's interior, the third layer would be the third closest of the layers to the container's interior, and the fourth layer would be the fourth closest of the layers to the container's interior.
In a further embodiment shown in
Exemplary embodiments of the containers described herein are typically made using an extrusion blow-molding process, such as that described in U.S. Pat. No. 4,846,359. In this process, molten thermoplastic material is extruded through an extrusion die head to form a substantially tubular parison. A mold is closed around the parison to pinch the parison's tail and form the bottom of the container. Pressurized air is then injected into the parison to expand it until it comes into contact with the mold's interior surface. After the formed container has cooled and solidified, the mold is opened and the finished container may be removed. The extruder or extruders used according to the invention may include, for example, any extruders suitable for multi-layer/coextruded processes, including shuttle, rotary wheel, and reciprocating-screw blow molding equipment.
Various embodiments of the invention may include one or more of the following advantages over prior art containers: (1) improved food product taste (due to a reduction in flavor scalping) compared to monolayer polyolefin containers; (2) improved product shelf life (which may be due, for example, to improved oxygen and/or chemical barrier characteristics); (3) improved clarity/gloss; (4) lower production cost than monolayer EPET bottles; and/or (5) improved container design flexibility compared to current PET bottles. It should be understood that particular embodiments of the invention may include advantageous characteristics other than those listed above and that some embodiments may include none of the above advantageous characteristics.
Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Accordingly, it should be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended exemplary concepts. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for the purposes of limitation.
This application claims priority to and the benefit of and is a continuation application of U.S. application Ser. No. 12,364,037 filed Feb. 1, 2012, which is a divisional of U.S. application Ser. No. 12/101,538 filed Apr. 11, 2008, which claims priority to and the benefit of U.S. Provisional Application Ser. No. 60/911,732, filed Apr. 13, 2007, the contents of each of which are hereby incorporated herein by reference in their entirety.
Number | Date | Country | |
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Parent | 12101538 | Apr 2008 | US |
Child | 13364037 | US |
Number | Date | Country | |
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Parent | 13364037 | Feb 2012 | US |
Child | 14171471 | US |