Abstract:
A double walled polycarbonate liquid holding vessel. The vessel may have an inner wall and an outer wall that are coupled to each other in a manner that defines an air tight gap therebetween. A resealable unit may be provided with the vessel that permits resealable access to the interior of the inner wall. The outer wall may be multi-section or single section, and various techniques may be used to conceal joints used to mount the outer wall to the remainder of the vessel. Various embodiments are disclosed.

Description:
FIELD OF THE INVENTION 
   The present invention relates to double walled plastic vessels for holding and/or storing liquids. More specifically, the present invention relates to such vessels that are formed of a durable, substantially transparent material. 
   BACKGROUND OF THE INVENTION 
   The prior art includes various double-walled plastic vessels, both resealable and non-resealable. Resealable examples include thermoses and like containers. Non-resealable examples include various double-walled tea and coffee cups (i.e., tumblers) and related items. 
   The prior art also includes transparent liquid holding vessels. These include a wide range of containers often formed of any of the standard commercial plastics. Examples include clear plastic soda and fruit juice bottles, soup and other liquid containers, and water bottles. Polyethylene terephthalate is an example of a plastic used to fabricate single use water bottles. 
   Higher end water bottles and like devices are known that are made of a polycarbonate resin sheet material. Polycarbonate is favored in some applications because it exhibits resistance to odors and flavors and thus different tasting beverages can be placed in a container with less likelihood of a taste “memory” from the previous beverage. Polycarbonate resin sheet material is also relatively durable compared to many conventional beverage container plastics. One commercial source of polycarbonate is General Electric which sells this material under the trade name “Lexan.” Nalgene is one maker of water bottles and laboratory equipment that are made of single walled polycarbonate. 
   Notwithstanding the benefits of polycarbonate, it is disadvantageous, among other reasons, in that it is relatively difficult to work with. It tends to be more viscous and rigid than other plastics and joining two components made of polycarbonate typically requires a weld that is unsightly. 
   Furthermore, relative to other types of beverage container plastic, the polycarbonate raw material is expensive. Coupling the material cost with the elevated cost of manufacture (associated with the difficulty in working with polycarbonate) renders polycarbonate products disadvantageously expensive. 
   Accordingly, due to problems associated with cost of material, difficulty in manufacturing, joining components and/or hiding unsightly joints, etc., prior art vessels using polycarbonate have been limited to single wall vessels or double walled vessels with only a single wall of polycarbonate material. The benefits of having a double walled polycarbonate vessel, for example, durability, insulating, transparent, non-odor absorbing, potentially microwave-able, etc., are not realized. 
   A need thus exists for a double walled polycarbonate liquid holding vessel that overcomes the deficiencies of the prior art and achieves some or all of the above stated benefits. A need further exists for a double walled polycarbonate liquid holding vessel that is resealable and at least in part transparent. 
   SUMMARY OF THE INVENTION 
   The present invention may be realized in several different embodiments and is not limited to the specific embodiments illustrated herein. 
   In one embodiment, the present invention includes a inner wall and an outer wall that are both formed of polycarbonate material. These walls are separated at least in part by an insulative gap. The inner and outer walls may be coupled to a resealable unit that may include a base and resealable lid or other resealable element. The inner and outer walls may couple directly to this unit. 
   The inner and/or outer wall may be formed of transparent polycarbonate to permit inspection of contents behind the wall. If both the inner and outer wall are transparent, then the contents of the vessel are visible. A transparent outer wall permits inspection of printing or aesthetic patterning on the exterior surface of the inner wall or on an insert provided between the inner and outer walls. 
   The outer wall can be multi-part to permit more aesthetic shaping of the vessel, including a taper towards the top or another shape, and/or the inclusion of other members that provide an desired aesthetic feature or provide a different printable surface or other marking or the like. 
   Beneficial features on the present invention include that the resultant vessel is durable (and resists scratches), insulative, non-metallic (i.e., potentially microwave-able), non-odor absorbing and may be configured to provide an outwardly disposed printable surface or surfaces, among others beneficial features. 
   The attainment of the foregoing and related advantages and features of the present invention should be more readily apparent to those skilled in the art, after review of the following more detailed description of the invention taken together with the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross-sectional side view of a polycarbonate double walled liquid holding vessel in accordance with the present invention. 
       FIGS. 2A-2D  are a series of perspective views of component parts of the polycarbonate double walled liquid holding vessel of  FIG. 1 . 
       FIG. 3  is a side elevation view of the polycarbonate double walled liquid holding vessel of  FIG. 1 . 
       FIGS. 4-7  are cross-sectional views (in whole or part) of other embodiments of a polycarbonate double walled liquid holding vessel in accordance with the present invention. 
   

   DETAILED DESCRIPTION 
   Referring to  FIG. 1 , a cross sectional side view of a polycarbonate double walled liquid holding vessel in accordance with the present invention is shown. From a top plan view, vessel  10  may be substantially round, though it should be recognized that vessel  10  may have any shape in top plan view, e.g., square, rectangular, polygonal, elliptical, amorphous or any other shape, without departing from the present invention. 
   Vessel  10  may include an inner wall  12  and an outer wall  14 . These walls  12 , 14  are preferably separated at least in part by a gap  15  that provides an insulative function. Gap  15  may contain only air or another substances such as foam, or any gaseous, liquid or solid material. Inner wall  12  and outer wall  14  are preferably sealed in an air-tight manner such that gap  15  is air-tight. Both inner wall  12  and outer wall  14  may respectively include bottoms  16 , 17  which may be formed integrally or otherwise. The bottoms  16 , 17  may be inter-coupled or spaced in a manner that maintains a continuous gap therebetween. Inter-coupling may be achieved through a variety of mounting structures including a ring  19  (shown in phantom lines) mounted to each bottom, or a plurality of “leg” members or an “X” or other geometrically shaped structure (from a top perspective), etc. The inter-coupling member(s)  19  serve(s) to provide enhanced stability to the double walled arrangement of device  10  (or the other devices herein, in addition to the welds ending in “60” discussed below). 
   Inner wall  12  is preferably formed of a polycarbonate resin sheet material such as Lexan or another suitable polycarbonate or polycarbonate-like material. The polycarbonate may be transparent (such that it can be readily seen through), translucent or partially to fully opaque. It is preferably transparent to permit visual inspection of the contents within, though it may be formed otherwise to achieve a desired appearance or function (e.g., reflective to reduce solar heating or dark to facilitate same, etc.). Outer wall  14  may also be formed of a polycarbonate resin sheet material or the like with the same or similar characteristics to those of inner wall  12 . The provision of a transparent polycarbonate material for the inner and outer walls permits visual inspection of the contents of vessel  10 . 
   Inner wall  12  and outer wall  14  are preferably attached to a resealable unit  30  that permits resealable access to cavity  40  inside inner wall  12 . Unit  30  may include a base  32  having an annular member  34  and a threaded neck  35  (or another suitable arrangement). A cap  36  may be threaded onto neck  35 . Note that while cap  36  is preferably threaded it may be resealable joined by other mechanisms including, but not limited to, snap-on, slide-on, a clamp, etc. Cap  36  may be moveably tethered to vessel  10  by leash  38 . Cap tethering arrangements are known in the art. 
   The inner and outer walls  12 , 14  are preferably coupled to base  32  of resealable unit  30 , though they may be otherwise coupled. Inner wall  12  is preferably formed integrally with base  32 . Known fabrication techniques for integral formation of these components, including an air-blow based fabrication of inner wall  12 , are generally known in the art. 
   Outer wall  14  is also coupled to resealable unit  30 . This may be achieved by coupling outer wall  14  to base  32  via a weld  60 . This weld is preferably formed by a sonic weld. Sonic welding is known in the art. Other joining techniques, however, may be used and these include, but are not limited to, glue, compression, threading (for example, a threaded outer wall could be removed for cleaning), etc. The upper region or collar  13  of outer wall  14  (and of inner wall  12 ) may be indented, particularly relative to base  32 , such that the typically unsightly weld  60  is substantially hidden underneath the base. 
   Outer wall  14  may also include a second weld. In the embodiment of  FIG. 1 , outer wall  14  may be formed of two sections  54 , 56 . The provision of two or more sections provides more opportunity for modifying the aesthetic features (shape, appearance, etc.) of the vessel. The provision of two or more sections can also be done in a manner that permits the inclusion of other surfaces or substrates, for example, to enhance function, aesthetics or to otherwise mark or distinguish the vessel. 
   In the embodiment of  FIG. 1 , sections  54 , 56  are each approximately one-half of the height of the outer wall, but could be otherwise arranged. The sections  54 , 56  are preferably welded together at weld  62  which may be a sonic weld as discussed above for weld  60 . A bottom portion  59 A of top section  54  and a top portion  59 B of bottom section  56  may be indented proximate second weld  62  to accommodate a band  58 . Band  58  may provide one or more of the following functions. It may hide weld  62 , be made of a material that facilitates a better grip by a user, be an additional substrate for printing or engraving, provide a desired aesthetic feature, support a logo or other type of commercial or personal marking, etc. 
   Gap  15  between the inner and outer walls may be continuous or discontinuous. A continuous gap is one that is substantially free of members or other structures that connect the inner wall to the outer wall. While these members enhance structural integrity, they may conduct cold (or heat) away from the inner wall towards the outer wall and hence compromise the thermal insulative properties of the vessel. Gap  15  is preferably continuous, but may be made otherwise without departing from the present invention. 
   Referring to  FIGS. 2A-2D , a series of perspective views that illustrate aspects of manufacturing a polycarbonate double walled vessel in accordance with the present invention are shown.  FIG. 2A  illustrates inner wall  12  with base  32  formed integrally therewith.  FIG. 2B  illustrates top section  54  which is slid over the configuration of  FIG. 2A  and welded to the underside of base  32  (at weld  60  of  FIG. 1 ). Bottom section  56 , shown in  FIG. 2C , is then slid over the remainder of inner wall  12  and welded to top section  54  (at weld  62  of  FIG. 1 ). Band  58 , shown in  FIG. 2D , is then positioned into complementary recess  59  (formed in part in top section  54  and bottom section  56 ) to hide weld  62 , among other potential reasons. Band  58  may include a design feature  57  such as an oval or other shaped section or substrate for printing on or for mounting/displaying an item (logo, etc.) or as otherwise alluded to herein. Band  58  may be made in whole or in part of an elastomeric material such as rubber or a rubber like material and is preferably stretched over bottom section  56  until it settles into recess  59 , or can be otherwise constructed. Note that the supplemental surface member that is band  58  need not be elastomeric, may be mounted by glue, welding or other mounting means and may be differently shaped, etc. 
   Referring to  FIG. 3 , a side elevation view of vessel  10  of  FIG. 1  in accordance with the present invention is shown.  FIG. 3  illustrates cap  36 , base  32 , leach  38 , top section  54  and bottom section  56  (of outer wall  14 ), band  58  and design feature  57 . 
   Referring to  FIG. 4 , a cross sectional side view of another polycarbonate double walled liquid holding vessel  110  in accordance with the present invention is shown. Vessel  110  is similar to vessel  10  of  FIG. 1  (for example, inner wall  112  is preferably formed in the same manner as inner wall  12 ), yet the outer wall  114  includes a top section  154  that is relatively large compared to the bottom section  156 , resulting in a weld  162  or other joint that is located towards the bottom of the vessel. While the top and bottom sections  154 , 156  could be configured to define a recess such as recess  59  of vessel  10  (to accommodate band  58 ), weld  162  may be sufficiently near the bottom of the vessel that a bottom piece  170 , perhaps made of non-slip rubber or the like, can be provided in such a manner as to hide weld  162  and/or provide any of the other functions of band  58 . The inner and outer walls  112 , 114  in this embodiment, between base  132  and bottom piece  170 , may be uninterrupted, providing a continuous substrate for clear viewing or patterning, etc. 
   Referring to  FIG. 5 , a cross sectional side view of another polycarbonate double walled liquid holding vessel  210  in accordance with the present invention is shown. Vessel  210  may share many of the same features and components of vessel  10  of  FIG. 1 , for example, inner wall  212  may be formed in the same manner as inner wall  12  of  FIG. 1 . One difference is that the outer wall  214  of vessel  210  is preferably made of a singular piece of polycarbonate material as opposed to two sections (top and bottom sections  54 , 56 ) as in vessel  10 . The singular piece outer wall  214 , which is free of a weld such as weld  62 , may present a smooth, unobstructed outward surface. Outer wall  214  is preferably mounted to vessel  210  by welding the top of outer wall  214  to base  232 . A sonic weld such as weld  60  or other suitable joining means may be used. The embodiment of  FIG. 5  potentially provides a double walled vessel with an unobstructed outer and inner wall  214 , 212 . 
   Referring to  FIG. 6 , a cross-sectional side view of a portion of a double walled vessel liquid holding vessel  310  in accordance with the present invention is shown.  FIG. 6  illustrates the upper portion of a vessel  310  in which the arrangement of base  332  and inner and outer walls  312 ,  314  is different from that of  FIG. 1 . Inner wall  312  has a more pronounced taper (than wall  12 ) and base  332  extends outward from a part near the end of the taper. 
   Outer wall  314  is joined to the underside of base  332 , preferably by welding at  360  (like weld  60 ). Relatively, weld  360  is farther out on base  332  than weld  60  on base  32 . 
   Referring to  FIG. 7 , a cross sectional side view of another polycarbonate double walled liquid holding vessel  410  in accordance with the present invention is shown. Vessel  410  may include an inner wall  412  and outer wall  414 . The outer wall may be formed in two sections: a top section  454  and a bottom section  456 . In contrast to the embodiment of  FIG. 1 , and other embodiments herein, the diameter of inner wall  412  towards a middle and lower region thereof is wider than the diameter of the outer wall  414  towards a top portion thereof. The configuration of vessel  410  may be achieve by fitting top section  454  over the top of the inner wall (in contrast to sliding it up from the bottom as was the preferred mounting method in the embodiments of  FIGS. 1-6 ) and sliding bottom section  456  up from the bottom. 
   Top section  454  may be joined to inner wall  412  at weld  460  (which may be a sonic or other type of weld) and bottom section  456  may be joined to top section  454  at weld  462 . Welds  460  and  462  may be sonic or another type of weld. The top and bottom sections  454 , 456  may be joined other than be welding. 
   While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention and the limits of the appended claims.