CROSS-REFERENCE TO RELATED APPLICATION
This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application Serial No. 60/301,540, filed Jun. 27, 2001, the disclosure of which is incorporated herein by reference.
1. Technical Field
Reusable plastic storage containers are disclosed. More specifically, reusable plastic storage containers having a multiple layer structure are disclosed. Still more specifically, reusable plastic storage containers are disclosed that have a multiple layer structure wherein at least one of the layers is fabricated from recycled plastic or other economical polymer material and wherein at least one of the visible outer layers is fabricated from virgin resin material.
2. Description of the Related Art
Reusable storage containers are known. One common type of reusable storage containers is fabricated from molded plastic in the form of an open-top box with a molded plastic lid. Such containers come in a variety of styles and colors.
One problem associated with currently available reusable storage containers is the relatively high manufacturing cost. Specifically, because the containers need to be aesthetically appealing due to their extended use, virgin resins are typically used in their fabrication. Colorants are added to impart any of a variety of colors to the containers. Because of the aesthetic appeal requirement, post-consumer regrind or post-industrial regrind resins are generally unacceptable because these recycled resins may include large quantities of contaminants, which give the resulting product a speckled and inconsistent appearance. As a result, the manufacturer may have to find a source or recycled material or regrind resin of a higher quality or of a desired color, which may drive up the cost of using a regrind resin.
Further, because reusable containers must be relatively rigid to permit stacking and carrying of heavy items, large quantities of virgin resins are used to fabricate a single container and lid combination. Because the containers are typically injection- or blow-molded, most of the cost of manufacture is tied up in materials costs. As a result, the requirement that virgin resins be used substantially drives up the cost of currently available reusable containers.
- SUMMARY OF THE DISCLOSURE
As a result, there is a need for improved reusable plastic container designs and methods of manufacture which can decrease the cost of manufacture of these items.
A more economical reusable three-dimensional storage container is disclosed.
In one refinement of the disclosure, a reusable three-dimensional storage container includes a first layer of a post-consumer or post-industrial regrind resin selected from the group consisting of linear low density polyethylene, high density polyethylene, polyvinylchloride and polyethyleneterephtalate, and a second layer of a virgin resin that is tied to the first layer. Preferably, the second layer serves as an outer layer to provide the requisite aesthetic appearance. However, it is anticipated that the second layer might serve as an inner layer in the event the reusable storage container is intended to hold food products and therefore the second layer is intended to be a food-contacting surface.
In a refinement, the container further includes a third layer disposed adjacent the first layer, opposite from the second layer. The third layer includes a virgin resin material, thereby providing a reusable three-dimensional storage container having three layers, two virgin resin layers which sandwich a recycled, regrind or other economical polymer layer therebetween.
In a further refinement of the disclosed container, the virgin resin layer(s) may include a colorant.
In still a further refinement of the disclosed container, a ratio of the thicknesses of the first layer to the thickness of either the single second layer or the combined thicknesses of the second and third layers ranges from about 60:40 to about 80:20. As a result, the bulk of the material used to fabricate the reusable storage container is either a recycled resin or an economical resin thereby substantially lowering the overall cost of the reusable container.
The economical or recycled first layer may also include a foaming agent to reduce the weight of the container or a filler such as calcium carbonate which will reduce the molded part cooling time.
BRIEF DESCRIPTION OF THE DRAWINGS
Other advantages of the disclosed container will be apparent to those skilled in the art from a review of the following figures and detailed description taken in conjunction with the appended claims.
The disclosed containers are described diagrammatically in the following drawings wherein:
FIG. 1 is a sectional view of a multilayer material used to fabricate a reusable storage container made in accordance with the disclosure;
FIG. 2 is a sectional view of another multilayer material used to fabricate a reusable storage container made in accordance with the disclosure;
FIG. 3 is a front sectional view of a reusable storage container and lid combination made in accordance with the disclosure;
FIG. 4 is an end sectional view of the container shown in FIG. 3;
FIG. 5 is an enlarged partial end view of the container shown in FIG. 3;
FIG. 6 is a top plan view of the container shown in FIG. 3 with the lid removed;
FIG. 7 is a perspective view of the container shown in FIG. 3 with the lid removed;
FIG. 8 is a front sectional view of two reusable storage containers as shown in FIG. 3 stacked one on top of another;
FIG. 9 is a sectional view of two parisons used to fabricate a two layer reusable storage container in accordance with the disclosure; and
FIG. 10 is sectional view of three parisons used to fabricate a reusable container in accordance with the disclosure.
- DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
The drawings are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the disclosed containers or which may render other details difficult to perceive may have been omitted. It should be understood, of course, that the disclosure is not necessarily limited to the particular embodiments illustrated herein.
FIG. 1 illustrates a two layer structure including a first layer 20 tied to a second layer 21. In order to reduce manufacturing costs, of which approximately 50% are due directly to the cost of materials and colorant, the first, thicker layer 20 can be fabricated from a post-consumer regrind or post-industrial regrind resin such as linear low density polyethylene, high density polyethylene, polyvinylchloride, polyethyleneterephthalate, nylon and mixtures thereof. Other, inexpensive resins may also be used to drive down the manufacturing costs, which will be apparent to those skilled in the art. The thinner, second layer 21 is preferably fabricated from a virgin resin to provide an improved outer appearance to a container or to provide a satisfactory food-contacting surface. Suitable resins for the second layer 21 include, but are not limited to, linear low density polyethylene, high density polyethylene, polyvinylchloride, polyethyleneterephthalate, nylon and mixtures thereof. Other suitable resins will be apparent to those skilled in the art depending upon the qualities desired (e.g., scratch resistance, stain resistance, resistance to oxidation, etc.).
Often, it is desirable to have either an improved inner and outer appearance to a reusable container or to provide an aesthetically appealing outer surface wall providing a suitable food-contacting inner surface. In such cases, containers can be fabricated from the three layer structure shown in FIG. 2 which includes a first layer 20, a second layer 21 and a third layer 22. The layer 22 can be made from like or similar materials as used for the layer 21 discussed above.
Suitable colorants for the outer and inner layers 21, 22 include, but are not limited to, various organic and inorganic pigments dispersed in a polyolefin carrier. Further, to reduce the weight of the overall structure formed, foaming agents can be used in the layer 20. Suitable foaming agents include, but are not limited to, citric acid mixed with sodium bicarbonate.
In addition, fillers may be added to the thicker layer 20 to reduce the cooling time of the molded part, reduce the gloss or sheen of the product and/or stiffen the resulting product. One suitable filler is calcium carbonate. Other suitable fillers include, but are not limited to, talc, barium sulfate, mica, glass, clay, titanium dioxide, dolomite, wood flower and flax.
Other functional properties may be incorporated into the inner and outer layers 22, 21, such as stain resistance. If stain resistance is desired for either layer 22, 21, the layers should incorporate a stain-resistant resin including, but not limited to, polysulphone, polymethylpentene, polycarbonate, polyetherimide, nylon, polyarylate, polyphenylsulphide, polyphenylene oxide, polyethersulphone, polyethyleneterephtalate, aromatic polyketone, liquid crystal polymer and mixtures thereof.
Further, fragrance can be added to any of the layers 20-22. Suitable fragrance includes various fragrance oils dispersed in a polyolefin carrier. Further, odor fighting additives, such as sodium bicarbonate can be added to one or more of the the resins utilized. Still further, using a foaming agent in at least the middle layer 20, and perhaps the outer layers 21, 22, can increase the insulating properties of the resulting container.
FIG. 3 is a partial elevational/sectional view of a container 25 that can be fabricated from either the two-layer structure of FIG. 1 or the three layer structure of FIG. 2 as discussed above. Container 25 includes a lid 26 secured to an open-top container 27. Container 27 includes bottom panel 28 disposed between and connected to opposing end panels 29, 31 as well as side panels 32, 33 (see also FIG. 7). The container portion 27 typically includes handles 30, 34. Further, to enhance sealing, the handles 30, 34 may include a bead 35, 36 around which a lip 37, 38 of the lid 26 is secured to provide a secure engagement. The side panels 32, 33 may also include recessed sections 41-44 (see also FIG. 7). The recess sections 41-44 enhance the structural integrity of the container 27. Further, as discussed below with respect to FIGS. 9-10, the recess sections 41-44 may also serve as a transparent window to make it easy for the consumer to view the contents of the container 27. Similarly, as shown in FIGS. 4 and 7, the end panels 29, 31 may also include recesses 45, 46. As shown in FIG. 8, the recesses 41-46 also enhance the stackability of two light container portions 27 a, 27 b.
Turning to FIGS. 9 and 10, a preferred method for fabricating the reusable containers disclosed above is a co-extrusion blow molding process. In such a process, a parison 50 as shown in FIG. 9 is co-extruded so that it has an inner layer 20 and an outer layer 21 (see FIG. 1). The parison 50 may then be blow molded into a three dimensional article such as the container portion 27 or lid portion 26 of the container assembly 25 shown in FIG. 3. In the embodiment shown in FIG. 9, clear resins are provided at 51, 52 to provide a window at one of the recesses 41-46 of either the side panels 32, 33 or end panels 29, 31 as shown in FIGS. 3, 4, and 7-8. Similarly, as shown in FIG. 10, a parison 60 may be provided with co-extruded layers 20-22 (see FIG. 2). Again, clear portion 61, 62 may be provided for purposes of a viewing “window” as described above.
The thickness of the layers 20-22 can vary, depending upon the embodiment. Preferably, the thickness of the layer 20 is at least twice as thick as the layer 21 in a two layer structure or the layer 20 is at least twice as thick as the combined thicknesses of the layers 21, 22 in a three layer structure. Suitable thickness ratios of the thickness of the layer 20 to the thickness of the layer 21 (two layer structure) or to the combined thicknesses of the layers 21, 22 (three layer structure) can range from about 50:50 to about 80:20.
The foregoing detailed description is given for clearness of understanding only, and no unnecessary limitation should be understood therefrom, as modifications within the scope of the invention may become apparent to those skilled in the art.