1. Field of the Invention
The invention relates to a collection container assembly that includes a plurality of nested containers formed from different respective materials and provides an effective barrier against water and gas permeability and for extending the shelf-life of assembly.
2. Description of the Related Art
Plastic tubes have an inherent permeability to water transport due to the physical properties of the plastic materials used to manufacture the tubes. Therefore, it is difficult to maintain the shelf-life of plastic tubes that contain a liquid additive. It is also appreciated that deterioration of the volume and concentration of the liquid additive may interfere with the intended use of the tube.
In addition, plastic tubes that are used for blood collection require certain performance standards to be acceptable for use in medical applications. Such performance standards include the ability to maintain greater than about 90% original draw volume over a one-year period, to be radiation sterilizable and to be non-interfering in tests and analysis.
Therefore, a need exists to improve the barrier properties of articles made of polymers and in particular plastic blood collection tubes wherein certain performance standards would be met and the article would be effective and usable in medical applications. In addition, a need exists to preserve the shelf-life of containers that contain liquid additives. The time period for maintaining the shelf-life is from manufacturing, through transport and until the container is actually used.
Some prior art containers are formed as an assembly of two or more nested containers. The nested containers are formed from different respective materials, each of which is selected in view of its own unique characteristics. Some nestable containers are dimensioned to fit closely with one another. Containers intended for such assemblies necessarily require close dimensional tolerances. Furthermore, air trapped between the two closely fitting nestable containers can complicate or prevent complete nesting. Some prior art container assemblies have longitudinal grooves along the length of the outer surface of the inner container and/or along the length of inner surface of the outer container. The grooves permit air to escape during assembly of the containers. However, the grooves complicate the respective structures and the grooved containers still require close dimensional tolerances.
Other container assemblies are dimensioned to provide a substantially uniform space at all locations between nested inner and outer containers. Air can escape from the space between the dimensionally different containers as the containers are being nested. Thus, assembly of the nestable containers is greatly facilitated. Additionally, the nestable containers do not require close dimensional tolerances. However, the space between the inner and outer containers retains a small amount of air and the air may be compressed slightly during final stages of nesting. Some such container assemblies are intended to be evacuated specimen collection containers. These container assemblies are required to maintain a vacuum after extended periods in storage. However, air in the space between the inner and outer containers is at a higher pressure than the substantial vacuum in the evacuated container assembly. This pressure differential will cause the air in the space between the inner and outer containers to migrate through the plastic wall of the inner container and into the initially evacuated space of the inner container. Hence, the effectiveness of the vacuum in the container assembly will be decreased significantly. These problems can be overcome by creating a pressure differential between the annular space and the inside of the inner container to cause a migration of air through the walls of the inner container. The inner container then is evacuated and sealed. This approach, however, complicates and lengthens an otherwise efficient manufacturing cycle.
The present invention is a container assembly comprising inner and outer containers that are nested with one another. The inner and outer containers both are formed from plastic materials, but preferably are formed from different plastic materials. Neither plastic material is required to meet all of the sealing requirements for the container. However, the respective plastic materials cooperate to ensure that the assembly achieves the necessary sealing, adequate shelf life and acceptable clinical performance. One of the nested containers may be formed from a material that exhibits acceptable gas barrier characteristics, and the other of the containers may be formed from a material that provides a moisture barrier. The inner container also must be formed from a material that has a proper surface for the specified clinical performance of the material being stored in the container assembly. Materials that exhibit good gas barrier characteristics may include: acrylic polymers and copolymers, including ABS, SAN; ethylene vinyl alcohol; polyesters; PET; PETG; PETN; PEN and engineered thermoplastics, including polycarbonate and blends thereof. Materials that exhibit good moisture or vapor barrier characteristics may include: polyoelfins, including polyethylene, polypropylene and copolymers thereof, cyclic olefin copolymers and chloro- and fluoro-polymers, including PVDC, PVDF, PVF, EPF and ACLAR. Preferably, the inner container is formed from polypropylene (PP), and the outer container is formed from polyethylene terephthalate (PET).
The inner and outer containers of the container assembly preferably are tubes, each of which has a closed bottom wall and an open top. The outer tube has a substantially cylindrical side wall with a selected inside diameter and a substantially spherically generated bottom wall. The inner tube has an axial length that is less than the outer tube. As a result, a closure can be inserted into the tops of the container assembly for secure sealing engagement with portions of both the inner and outer tubes. The outer surface of the inner tube and the inner surface of the outer tube are dimensioned to substantially nest with one another.
The inner tube of the container assembly may be formed with a small hole through the cylindrical side wall of the inner tube at a location spaced slightly from the open top. The hole permits venting of air from the space between the inner and outer tubes as the inner tube is being slid into the outer tube. The closure of the assembly includes an internal portion that will telescope within portions of the inner and outer tubes near the top ends of the respective tubes. Thus, the closure will seal the small hole adjacent the open top of the inner tube.
A further embodiment of the subject invention provides an inner tube that is sufficiently smaller than the outer tube to provide a small annular gap between the inner and outer tubes. The small annular gap between the inner and outer tubes permits air to escape easily as the inner tube is being telescoped into the outer tube. The outer surface of the inner tube includes a bead extending partly around the outer tube at a location near the open top. The bead may be formed unitarily with the inner tube or may be applied to the inner tube by adhesive or the like. The outside diameter defined by the bead is substantially equal to the inside diameter defined by the outer tube. The bead does not define a complete annulus. Rather, at least one gap is defined in the bead. Air can escape readily from the space between the inner and outer tubes as the cross-sectionally small inner tube is being telescoped into the outer tube. A complete annular bead around the inner tube would prevent further escape of air as the inner tube approaches its final nested position within the outer tube. However, the small gap in the annular bead permits the escape of air as the inner tube approaches its final nested position within the outer tube. Thus, air in the small annular gap between the inner and outer tubes is at ambient pressure and will not define a high pressure area that is likely to migrate through the plastic material of the inner tube and into the space defined by the inner tube. After assembly, the inner tube is spun relative to the outer tube. Thus, a friction weld is created between the inner and outer tubes for securely sealing the space between the tubes.
Another embodiment of the subject invention provides an inner tube with an outside diameter that is sufficiently smaller than the inside diameter of the outer tube to define an annular gap therebetween. Thus, as with the previous embodiment, the inner tube can be telescoped readily into the outer tube without generating a region of compressed air between the inner and outer tubes. The closure of this assembly includes a short cylindrical wall dimensioned to telescope into the annular space between the inner and outer tubes at a location substantially adjacent the open top of the inner tube. Thus, the short cylindrical wall of the closure seals the space between the inner and outer tubes. The closure also includes an inner section disposed and dimensioned to seal with the inner circumferential surface of the inner tube. An alternate to this embodiment provides a closure with a radially aligned step to cover the open top of the annular space between the inner and outer tubes without entering the annular space between the inner and outer tubes. The closure of this embodiment also includes an inner portion to seal with the inner circumferential surface of the inner tube.
A further embodiment of the subject invention includes an inner tube with an outside diameter that is sufficiently smaller than the inside diameter of the outer tube to define an annular gap therebetween. Thus, as with the previous embodiment, the inner tube can be telescoped readily into the outer tube without generating a region of compressed air between the inner and outer tubes. Portions of the inner tube at locations near the open top include a circumferentially extending weakened region. The weakened region may be created by an annular groove extending around the outer circumferential surface of the inner tube. A similar annular groove may be formed around the inner circumferential surface at a location substantially aligned with the annular groove on the outer circumferential surface. The closure of this assembly includes a tapered region with a small diameter leading end that defines a diameter approximately equal to the inside diameter of the inner tube. The closure then widens to an outside diameter substantially equal to the inside diameter of the outer tube. The tapered configuration enables the closure to function as a wedge that causes the inner tube to deform outwardly as the closure is being urged into the open tops of the inner and outer tubes. Thus, the portions of the inner tube adjacent the open top will flare outwardly and will be urged tightly against the inner circumferential surface of the outer tube as the closure is being urged into the open tops of the nested tubes.
Still a further embodiment includes an inner tube that has an outside diameter less than the inside diameter of the outer tube. Accordingly, the inner tube can be inserted into the outer tube without generating compressed air in the annular space between the inner and outer tubes. Portions of the inner tube near the open top may be flared out to an outside diameter equal to or slightly greater than the inside diameter of the outer tube. The assembly of the inner tube into the outer tube may be carried out by an annular collar with an inside diameter slightly less than the outside diameter of the flared open top of the inner tube and with an outside diameter approximately equal to the inside diameter of the outer tube. The collar is forced over the flared top of the inner tube and hence reduces the diameter of the flared top slightly. The collar of the assembly device includes a notch that extends from a location below the flared top of the inner tube to a location above the inner tube. The notch functions as a vent that permits the escape of air as the inner tube is being telescoped into the outer tube. The assembly apparatus also includes a plunger dimensioned to telescope into the open top of the collar. Thus, the plunger will engage the top of the inner tube. As the inner tube reaches or approaches complete assembly within the outer tube, the collar is withdrawn up while the plunger is urged down. As a result, the collar separates from the flared open top of the inner tube, and the flared top resiliently expands into sealing engagement with the inner circumferential surface of the outer tube.
Another embodiment of the subject invention includes an inner tube with an outside diameter that is sufficiently less than the inside diameter of the outer tube to define an annular gap between the inner and outer tubes. Thus, as with the previous embodiments, the inner tube can be telescoped into a fully nested condition within the outer tube without creating compressed air in the annular space between the inner and outer tubes. The assembly of this embodiment further includes a retaining ring. The retaining ring is dimensioned to nest with and seal the space between the inner and outer tubes. The sealing can be facilitated by chamfering the outer top surface of the inner tube and/or forming the retaining ring with a taper.
An assembly in accordance with a first embodiment of the subject invention is identified generally by the numeral 10 in
Outer tube 12 is unitarily formed from PET and includes a spherically generated closed bottom wall 18, an open top 20 and a cylindrical wall 22 substantially extending therebetween. Outer tube 12 defines a length “a” from the interior of the bottom wall 18 to the open top 20. Side wall 22 of outer tube 12 includes a cylindrically generated inner surface 24 with an inside diameter “b”. However, side wall 22 may taper slightly from open top 20 to closed bottom wall 18 to facilitate molding.
Inner tube 14 is formed unitarily from polypropylene and includes a spherically generated closed bottom wall 26, an open top 28 and a substantially cylindrical side wall 30 extending therebetween. Inner tube 14 defines an external length “c” that is less than internal length “a” of outer tube 12. However, side wall 30 may taper slightly from open top 28 to closed bottom wall 26 to facilitate molding. The extreme top of inner tube 14 includes an outwardly flared region 32 with a maximum outside diameter approximately equal to inside diameter “b” of side wall 22 on outer tube 12. Inner tube 14 is further characterized by a pin hole 34 that extends through side wall 30 of inner tube 14 at a location slightly below the outward flare 32.
Closure 16 preferably is formed from rubber and has a bottom end 36 and an internal section 37 adjacent bottom end 36. Closure 16 also has top end 38 and an external section 39 adjacent top end, as shown in
Assembly 10 is assembled by slidably inserting inner tube 14 into open top 20 of outer tube 12, as shown in
The assembly of inner tube 14 with outer tube 12 can be sealed by closure 16. In particular, the tapered portion of internal section 37 facilitates initial insertion of closure 16 into open top 20 of outer tube 12. Sufficient axial advancement of closure 16 into open top 20 will cause cylindrical outer portion of internal section 37 to sealingly engage internal surface 24 of outer tube 12. Further insertion will cause the tapered portion of internal section 37 to sealingly engage the internal surface of inner tube 14 adjacent open top 28. Dimension “h” of internal section 37 is selected to ensure that internal section 37 seals pin hole 34 approximately when external section 35 abuts top end 20 of outer tube 12.
A second container assembly in accordance with the subject invention is identified generally by the numeral 40 in
Inner tube 42 can be telescoped within outer tube 12. The outside diameter of portions of inner tube 42 below bead 52 permit air to escape from outer tube 12 as inner tube 42 is urged into outer tube 12. Sufficient insertion of inner tube 42 within outer tube 12 will bring bead 52 into contact with inner surface 24 of side wall 22 on outer tube 12. This engagement between bead 52 and inner surface 24 will restrict the outflow of air from the space between inner and outer tubes 42 and 12. However, gap 54 in bead 52 will permit air to escape as inner tube 42 is moved into its final position. Accordingly, compressed air will not exist within container assembly 40. Closure 16 may be urged into the open tops of the nested inner and outer tubes 42 and 12 to seal the inside of both inner tube 42 and the annular space between inner and outer tubes 14 and 12.
A further embodiment of the subject container assembly is identified generally by the numeral 60 in
Assembly 70 includes an inner closure 72 and an outer cap 74. Inner closure 72 is formed from an elastomeric material and has a bottom end 76 and a top end 78. Closure 72 includes an external section 80 extending down from top end 78. External section 80 is cross-sectionally larger than inner circumferential surface 24 of outer tube 12. Hence, external section 80 of closure 72 is dimensioned to sit on open top 20 of outer tube 12. Closure 72 further includes an internal section 82 extending up from bottom end 76. Internal section 82 defines an outside diameter slightly greater than inside diameter “b” of outer tube 12. Thus, internal section 86 is dimensioned to sealingly engage inner circumferential surface 24 of outer tube 12. Internal section 86 is formed further with an annular groove 88 extending up into bottom end 76. Groove 88 is spaced inwardly from the outer circumferential surface of internal section 86 by a distance substantially equal to the radial dimension of the annular gap between inner tube 62 and outer tube 12. Thus, as shown most clearly in
Cap 74 is of known construction and includes an annular top wall 90 for abutting top end 78 of closure 72. Cap 74 further includes a cylindrical skirt 92 that extends down from top wall 90. Skirt 92 is cross-sectionally dimensioned to frictionally engage the outer circumferential surface of external section 80 of closure 72. Skirt 92 is longitudinally dimensioned to extend down beyond external section 80 of closure 72.
A further embodiment of a container assembly in accordance with the subject invention is identified generally by the numeral 100 in
Inner tube 102 is characterized by an annular groove 110 extending around the outer circumferential surface of side wall 108 at a location spaced slightly below open top 106. In the illustrated embodiment, a second annular groove 112 is formed around the inner circumferential surface of side wall 108 at a location aligned with groove 110. The grooves 110 and 112 weaken side wall 108 sufficiently to facilitate an outward flaring of side wall 108 at locations between open top 106 and grooves 110, 112.
Container assembly 100 further includes a closure assembly 114. Closure assembly 114 includes an outer cap 74 substantially identical to the outer cap 74 described and illustrated with respect to
A further embodiment of the container assembly of the subject invention is identified generally by the numeral 130 in
Container assembly 130 further includes a retaining ring 142. Retaining ring 142 is dimensioned to fit in the annular generally V-shaped space defined between inner surface 24 of outer tube 12 and chamfer 140 at open top 136 of inner tube 132. As shown most clearly in
Container assembly 130 is assembled by telescoping inner tube 132 into open top 20 of outer tube 12. The relative dimensions permits an easy escape of air from outer tube 12 as inner tube 132 is being inserted. A small annular space will be defined between inner tube 132 and outer tube 112 after complete insertion of inner tube 132. Air in this space will be substantially at ambient pressure. The space between inner and outer tubes 132 and 12 can be sealed by mounting retaining ring 142 onto chamfer 140. Thus, retaining ring seals 142 against chamfer 140 and against inner circumferential surface 24 of tubular side wall 22 on outer tube 12. Retaining ring 142 can be friction welded in position to provide a substantially hermetic seal of the annular space between inner tube 132 and outer tube 12. Closure 144 then can be urged into the open tops 20 and 136 substantially as with the previous embodiments.
A further alternate of the subject container assembly is identified generally by the numeral 150 in
Assembly venting device 162 is used by first telescoping tubular body 164 over inner tube 152, as shown in
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US03/27124 | 8/29/2003 | WO | 00 | 5/5/2004 |
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WO2004/022234 | 3/18/2004 | WO | A |
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