Stretch blow molded pipette, and system and method for forming same

A stretch blow molding method may include fabricating a preform (e.g., by molding, optionally while a core pin rotates within a mold cavity), heating the preform to a softening temperature, stretching and thereby elongating at least a portion of the heated preform, blowing the elongated preform with pressurized fluid within a mold cavity, and cooling the resulting pipette. A system for fabricating a stretch blow molded pipette includes a first mold defining a mold cavity for producing a preform. A stretch rod drive unit is configured to move a stretch rod within an interior of the preform to form an elongated preform, and a second mold defines blow molding cavity and a molding surface to contain expansion of the elongated perform when subjected to blowing by supplying pressurized fluid to an interior thereof.

FIELD

The present disclosure relates generally to unitary measuring pipettes, as well as systems and methods for forming the same by, for example, stretch blow molding.

BACKGROUND

Pipettes are well-known tubular devices that usually have openings at both ends, and are designed to dispense measured quantities of liquids. Pipettes have had widespread usage in a number of industries where accurate measurement and delivery of fluids are required, particularly the medical and laboratory testing and analysis fields. Measuring pipettes typically embody straight glass or plastic tubes with one tapered end, and are calibrated into small divisions so that various amounts of liquid can be measured with the same pipette. Measuring pipettes include Mohr pipettes (with graduation marks that end before tapering begins proximate to the tip) and serological pipettes (with graduation marks that continue to a tapering region proximate to the tip), which both include an open tip and an open mouthpiece

Multiple different methods exist for fabricating pipettes, including (i) welding premade mouthpiece and tip components to a hollow tube, (ii) reheating a thick tube followed by drawing the tube downward in open air and trimming the pipette at one or both ends to form a tip and a mouthpiece, and (iii) molding with application of a pressure differential, including vacuum forming and blow molding. Each of these methods entails tradeoffs with respect to cost, quality, performance, and/or processing steps, as detailed below.

Welding premade mouthpiece and tip components to a hollow tube according to method (i) outlined above results in formation of weld seams that may create undesirable residue or particulate in the resulting pipette, and may also create bumps or ridges that may accumulate fluid and contaminants inside a pipette.FIG.1Ais a schematic side cross-sectional view of a welded pipette10including a tubular body region14arranged between a mouthpiece region12and a tip region16, with a hollow interior18. Weld joints13,15are provided between respective pairs of the mouthpiece, tubular body, and tip regions12,14,16, and may be produced by ultrasonic welding. The tip region16is tapered in width between the adjacent weld joint15and a tip opening17. Optionally, the mouthpiece region12includes inner and outer diameter dimensions that are smaller than corresponding dimensions of the tubular body region14, with the mouthpiece region12further including a filter19positioned between the adjacent weld joint13and a mouthpiece opening11. As shown, wall thicknesses of the mouthpiece, tubular body, and tip regions12,14,16may be substantially the same. A typical lower limit of wall thickness for welded pipettes is about 0.6 mm, to enable the weld joints13,15to be fabricated between the mouthpiece, tubular body, and tip regions12,14,16.

FIG.1Bis a flowchart outlining steps of a method20for fabricating a welded pipette according toFIG.1A. A first step21includes extruding, cooling, and cutting tubes to be used to form a tubular body. A second step22includes handling (e.g., transporting and storing) the work-in-process (“WIP”) tubes. A third step23includes facing the WIP tubes in preparation for welding. A fourth step24includes molding pipette mouthpieces suitable for mating with tubes fabricated in the first step21. A fifth step25includes handling the WIP pipette mouthpieces. A sixth step26includes molding pipette tips suitable for mating with tubes fabricated in the first step21. A seventh step27includes handling the WIP pipette tips. Eighth and ninth steps28,29include welding the mouthpieces to one end of the faced tubes, and welding the tips to another end of the faced tubes, respectively. A tenth step30includes printing graduations on exterior surfaces of the welded pipettes, and an eleventh step31includes inserting filters into mouthpieces of the pipettes. As will be evident upon review ofFIG.1B, the method20involves a multitude of processing steps.

Reheating a thick tube followed by drawing down and trimming the pipette at one or both ends to form a tip and a mouthpiece according to method (ii) outlined above entails significant variability in tip and mouthpiece openings, variability in shape transitions between tip, body, and mouthpiece regions, and variations in overall quality. Additionally, since wall thicknesses of the tip and mouthpiece regions are determined by a thickness of the starting tube, the body portion of a resulting pipette may have a wall thickness substantially thicker than necessary, resulting in excessively high material cost.FIG.2Ais a schematic side cross-sectional view of a drawn pipette40including a tubular body region44arranged between a mouthpiece region42and a tip region46, with a hollow interior48. Transition regions43,45are provided between respective pairs of the mouthpiece, tubular body, and tip regions42,44,46. The tubular body region44has a greater wall thickness than wall thicknesses of the mouthpiece region42and the tip region46. Each transition region43,45includes a variable wall thickness that tapers with increasing distance away from the tubular body region44. A tip opening47is provided at the end of the tip region46. The mouthpiece region42includes a filter49positioned between the adjacent transition region43and a mouthpiece opening41. Due to inherent variations in the drawing process, positions and dimensions of the tip region46, the mouthpiece region42, and the transition regions43,45may vary from one pipette to another.

FIG.2Bis a flowchart outlining steps of a method50for fabricating a drawn pipette according toFIG.2A. A first step51includes extruding, cooling, and cutting thick tubes to be used as body precursors. A second step52includes handling (e.g., transporting and storing) the WIP tubes. A third step53includes facing the WIP tubes in preparation for heating and drawing steps. A fourth step54includes heating the tubes and drawing tip regions. A fifth step55includes heating the tubes (if not cooled from the fourth step54) and drawing mouthpiece regions to form drawn pipettes. A sixth step56includes printing graduations on exterior surfaces of the drawn pipettes, and a seventh step57includes inserting filters into mouthpieces of the pipettes. As will be evident upon review ofFIG.2B, the method50involves numerous processing steps.

Molding with application of a pressure differential according to method (iii) outlined above is capable of producing high quality pipettes free of weld seams, but such method typically results in formation of longitudinally spaced, raised circumferential ring shapes or ribs (i.e., witness features resulting from incursion of softened material into gas escape passages) along an exterior surface of a tubular pipette body, wherein such ring-shaped witness features tend to obscure clarity and readability of graduation lines printed on an exterior of the body. An exemplary pipette60that may be produced by molding with application of a pressure differential (according to method (iii) outlined above) is shown inFIG.3, which is substantially the same as the first figure of International Publication No. WO 2017/091540 A1 entitled “Unitary Serological Pipette and Methods of Producing the Same,” and assigned to Corning Incorporated.) Each of a mouth region62, a body region64, and a tip region66has a curved inner surface71that encloses a space, and has a corresponding diameter (namely, a mouth diameter72, a body diameter74, and a tip diameter76). The pipette60includes a mouth73and a tip75that are aligned along a longitudinal axis, with a filter79proximate to the mouth73. Optionally, the pipette60may have a mouth-body transition region63between the mouth region62and the body region64, as well as a body-tip transition region65between the body region64and the tip region66. If the pipette60is molded of a continuous material without formation of weld joints (e.g., between the tip region66, the body region64, and the mouthpiece region62), then a substantially smooth inside surface69may be provided in the transition regions63,65, thereby reducing potential for retention of fluid and/or particulate material. The pipette60may also include a series of graduated volumetric markings77printed (or imprinted) along an outside surface68of (at least) the body region64to indicate a volume of liquid contained in a space78within the pipette60. The pipette60may be sized to hold a particular volume of liquid (e.g., 1 mL, 2 mL, 5 mL, 10 mL, 25 mL, 50 mL, 100 mL, or another desired volume). Optionally, the diameter74of the body region64may be greater than either the diameter72of the mouth region62or the diameter76of the tip region66. The pipette60may be manufactured of any suitable materials, such as glass or polymers (e.g., polystyrene, polyethylene, or polypropylene).

Fabrication of the pipette60by molding with application of a pressure differential may include supplying a heated parison (e.g., a tube or perform, typically in the shape of a uniform hollow cylinder) into a mold, and creating a differential pressure between an interior and an exterior of the parison to cause the parison to expand and conform to a cavity of the mold. This differential pressure may be created by either supplying pressurized gas (e.g., compressed air at 0.05 to 1.5 MPa) into an interior of the parison, or by generating subatmospheric pressure conditions (also known as vacuum conditions, e.g., at a pressure of 0.01 to 0.09 MPa) along surfaces defining the cavity of the mold. Either case requires the presence of passages in surfaces of the mold to permit the escape of gas between an exterior of the parison and the cavity, to enable expansion of the heated parison. Typically, circumferential channels are formed in curved surfaces of a mold (e.g., in corresponding mold halves) to serve as gas escape passages during a molding operation. Following fabrication of a pipette using mold halves defining registered transverse recessed channel segments along a curved inner surface, a resulting pipette will exhibit longitudinally spaced, raised circumferential rings (i.e., circumferential witness features) along an exterior surface of the tubular pipette body. These circumferential witness features may undesirably interfere with printing of the graduated volumetric markings, and may also distract a user from quickly and accurately reading fluid volumes using the graduated volumetric markings. After sufficient cooling of the expanded material (now embodied in a pipette), the mold is opened, the pipette is ejected, and the mold may receive another heated parison to repeat the process.

Given the foregoing, there is a need for pipettes free of the aforementioned shortcomings, as well as a need for improved systems and methods for producing pipettes.

SUMMARY

Unitary measuring pipettes (e.g., serological pipettes) formed by stretch blow molding, as well as systems and methods for forming unitary measuring pipettes by stretch blow molding, are provided herein. Stretch blow molding includes a stretching of a prefabricated preform, and blowing of a stretched perform within a mold cavity. The preform may be profiled to distribute material in desired locations, resulting in precise body thickness of a pipette. A stretch blow molded pipette includes a tubular body between a tip region and a mouthpiece region. The tip region comprises an average wall thickness that is greater than a wall thickness of the tubular body, and the pipette is devoid of any joint (e.g., a welded joint), such as would be present in a welded pipette between the tubular body and the tip region, and between the tubular body and the mouthpiece region. A stretch blow molded pipette may comprise thermoplastic material, such as biaxially oriented thermoplastic material. A stretch blow molding method may include fabricating a preform (e.g., by molding), heating the preform to a softening temperature, stretching and thereby elongating at least a portion of the heated preform, blowing the elongated preform with pressurized fluid (e.g., gas such as air) within a mold cavity to cause the heated preform to expand into contact with a molding surface and assume a pipette shape, and cooling the blown and elongated preform. In certain embodiments, the stretching may be performed while the preform is outside the mold cavity, followed by closure of mold halves (defining the mold cavity) around the stretched preform. In certain embodiments, the preform may be fabricated by molding while a core pin rotates within a preform mold cavity to orient polymer chains in a radial direction. A system for fabricating a stretch blow molded pipette may include a first mold defining a preform mold cavity, and a rotary drive unit configured to achieve relative rotation between a core pin (positionable within the preform mold cavity) and the first mold during molding of a hollow preform. The system may still further include a stretch rod drive unit that is configured to move a stretch rod within an interior of the preform to form an elongated preform, and a second mold defining a molding surface and a blow molding cavity to contain expansion of the elongated perform when pressurized fluid is supplied to an interior of the elongated preform.

In accordance with certain aspects of the present disclosure, a stretch blow molded pipette comprising a tubular body arranged between a tip region and a mouthpiece region is provided. The tip region comprises an average wall thickness that is greater than a wall thickness of the tubular body, and the stretch blow molded pipette is devoid of any joint (i) between the tubular body and the tip region, and (ii) between the tubular body and the mouthpiece region.

In accordance with additional aspects of the present disclosure, a method for fabricating a pipette comprising a tubular body arranged between a tip region and a mouthpiece region is provided. The method comprises a step of fabricating (molding) a preform comprising a hollow tubular shape. The method comprises an additional step of heating the preform to within a softening temperature of a material of the preform. The method comprises a further step of stretching at least a portion of the heated preform to form an elongated preform. The method comprises a further step of blowing at least a portion of the elongated preform within a mold cavity by applying a pressurized fluid to an interior of the heated preform to cause the heated preform to expand into contact with a molding surface. A further method step comprises cooling the blown and elongated preform.

In accordance with additional aspects of the present disclosure, a system for fabricating a pipette comprising a tubular body arranged between a tip region and a mouthpiece region by a stretch blow molding process is provided. The system comprises a first mold defining a preform mold cavity configured to permit molding of a hollow preform therein. The system further comprises a preform stretching apparatus comprising a stretch rod positionable within an interior of the hollow preform and coupled with a stretch rod drive unit that is configured to move the stretch rod within the interior of the hollow preform to form an elongated preform. The system further comprises a second mold defining a blow molding cavity configured to contain at least a portion of the elongated preform while pressurized fluid is supplied to an interior of the elongated preform to cause the elongated preform to radially expand and contact a molding surface of the second mold.

Additional features and advantages of the subject matter of the present disclosure will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the subject matter of the present disclosure as described herein, including the detailed description which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description and the following detailed description present embodiments of the subject matter of the present disclosure, and are intended to provide an overview or framework for understanding the nature and character of the subject matter of the present disclosure as it is claimed. The accompanying drawings are included to provide a further understanding of the subject matter of the present disclosure, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the subject matter of the present disclosure and together with the description serve to explain the principles and operations of the subject matter of the present disclosure.

DETAILED DESCRIPTION

The present disclosure relates to unitary measuring pipettes (e.g., serological pipettes), and methods and apparatuses for forming unitary measuring pipettes by stretch blow molding. Stretch blow molding includes a stretching of a prefabricated preform, and blowing of a stretched perform within a mold cavity. The preform may be profiled to distribute material in desired locations, resulting in precise body thickness of a pipette. By prefabricating (e.g., molding) a preform, the tip region and mouthpiece region may be formed prior to stretching, thereby enabling precise and repeatable formation of these regions in a resulting pipette, and further enabling these regions to have an increased thickness relative to a tubular body. Use of a preform with a prefabricated tip and mouthpiece regions also eliminates the need for any cutting typically required for drawn or welded pipettes.

Stretch blow molding methods may be used to produce pipettes of biaxially oriented polymer material. A brief introduction to polymer orientation principles follows, to enable understanding of biaxial orientation.

The ability of a polymer to sustain a mechanical load depends on the strength of covalent bonds and the forces between the molecules. In an amorphous system, much of a mechanical load is carried by van der Waals interactions and random coil entanglements between chains. If, however, a substantial fraction of the polymer chains can be aligned (i.e., oriented) in the load-bearing direction, then a larger portion of the load can be transmitted to the main-chain covalent bonds. In amorphous systems only chain orientation occurs, whereas both chains and crystalline regions can be aligned in semicrystalline polymers. In both amorphous and semicrystalline systems, orientation of polymer chains leads to an increased strength in the direction of orientation. Uniaxially oriented materials typically exhibit low strength in a direction perpendicular to the polymer chain orientation.

Polymer chains are oriented by subjecting them to extensional strain (flow) in a melted or near-melted state. Biaxial orientation of a polymer material can be achieved by straining the material in two directions (e.g., a radial direction and a lengthwise direction) at elevated temperature, and allowing the material to cool while strained. As compared to unoriented or uniaxially oriented polymers, biaxial orientation allows the production of reduced thickness films, containers, and objects having enhanced mechanical and optical properties.

Biaxial orientation may be obtained by stretch blow molding by expanding dimensions of, and thereby straining, a hot preform in the radial direction (e.g., by blowing) and the longitudinal axial direction (e.g., by stretching). Depending on the relative dimensions of the preform and the finished pipette, the degree of radial expansion attributable to blowing may be insufficient to impart a significant degree of radial orientation of polymer chains in a stretch blow molded pipette. To address this situation, in certain embodiments radial orientation of polymer chains may be enhanced through use of a spinning core in contact with molding material of a preform to radially shear the preform material during the preform molding process. The initial radial orientation of polymer chains in the preform, when augmented by axial orientation obtained during axial stretching, will create biaxial orientation of polymer chains in a finished pipette.

In certain embodiments, a preform and a resulting pipette (including a tubular body region, a tip region, and a mouthpiece region) may comprise thermoplastic material, which may be biaxially oriented. In certain embodiments, the thermoplastic material may comprise crystalline polystyrene, poly(styrene-butadiene-styrene), polyethylene terephthalate, polypropylene, copolymers of any two or more of the foregoing polymers, and/or recycled streams of any one or more of the foregoing polymers.

FIG.4Aillustrates a pipette80fabricated by stretch blow molding according to one embodiment of the present disclosure. The pipette80includes a tubular body region84arranged between a mouthpiece region82and a tip region86, with a hollow interior90. A first abrupt transition region83is provided between the mouthpiece region82and the tubular body region84, and a second abrupt transition region85is provided between the tubular body region84and the tip region86; however, such transition regions83,85embody continuously uniform material without presence of any welded joints. An outer diameter of the tip region86is tapered in width with increasing proximity to a tip opening87; however, the tip region86optionally includes a bore88having a substantially constant inner diameter. Such features of the tip region86may be fabricated during a preform molding operation. In certain embodiments, a tip region86may include a non-constant inner diameter. Optionally, the mouthpiece region82includes inner and outer diameter dimensions that are smaller than corresponding dimensions of the tubular body region84, with the mouthpiece region82further including a filter89arranged therein between an open mouthpiece end81and the tubular body region84. The tubular body region84further includes graduated volumetric markings91printed (or imprinted) along an outside surface to indicate a volume of liquid contained in the hollow interior90. As shown, an average wall thickness of the tip region86is greater than a wall thickness of the tubular body region84, and the mouthpiece region82has an average wall thickness that is greater than the wall thickness of the tubular body region84. Additionally, the region of greatest wall thickness of the pipette80is within the tip region86and/or at the transition85between the tip region86and the tubular body region84.

FIG.4Bis a flowchart outlining steps of a method94for fabricating stretch blow molded pipettes according toFIG.4A. A first step95includes fabricating (e.g., molding) performs and conveying the preforms to a preform stretching apparatus or machine. In certain embodiments, molding of a preform may include injection molding or compression molding in a first mold defining a preform mold cavity configured to permit molding of a hollow preform therein. Optionally, the first mold may be configured to receive a core pin within the preform mold cavity, and a rotary drive unit may be employed to achieve relative rotation between the core pin and the first mold during molding of the hollow preform within the first mold. Such rotation may include rotation of the core pin while the first mold remains stationary, or may include rotation of the first mold while the core pin remains stationary. To complete molding of the preform, the preform is cooled. A second step96includes heating the preform to a softening temperature of the preform material in preparation for stretching and blowing of the preform. In certain embodiments, at least one infrared heating element may be used to heat the preform. A third step97may include depositing ink on a molding surface or inserting a label into a mold cavity to be used for blowing the preform, prior to a blowing operation, in order to impart markings onto an outer surface of a pipette during a blowing process. A fourth step98includes stretching the preform to form an elongated preform, blowing the elongated preform to promote radial expansion of at least a portion thereof, cooling the stretched and blown material to form a pipette, and removing the pipette from a blow molding cavity of a mold (e.g., by separating mated mold halves). A fifth step99includes insertion of a filter (e.g., using a filter plugging mechanism) into a mouthpiece region of a resulting pipette. Thereafter, the pipette may be conveyed to a sterilization and/or packaging station for further processing. In certain embodiments, the stretch blowing manufacturing steps may be performed in aseptic (e.g., cleanroom) environment, thereby avoiding the need for sterilization after fabrication steps are complete.

In certain embodiments, ultrasonic excitation may be applied to an injection screw and/or mold cavity during molding of the preform, to promote attainment of random orientation of polymer chains within the preform, such that need for a spinning core may be eliminated.

In certain embodiments, a stretch rod positionable within at least a portion of a hollow preform may be used to effectuate stretching of a preform and form an elongated preform. A stretch rod may be coupled with a stretch rod drive unit that is configured to move the stretch rod (e.g., by translation) within the interior of a preform. In certain embodiments, a stretch rod comprises a tapered region having a shape matching an interior taper of a transition region between a tip region and a tubular body of a pipette. In certain embodiments, a chuck or clamp may be used to immobilize a mouthpiece end of the preform during movement of the stretch rod within the interior of the preform to form the elongated preform. In certain embodiments, a preform stretching operation may be performed outside of a mold having a blow molding cavity (e.g., with a preform stretching apparatus proximate to open sections of second mold), such that after stretching of the preform, the elongated preform may be transferred to the blow molding cavity (e.g., by closing mold cavity halves around the elongated preform), and radial expansion of the elongated preform may be performed thereafter.

FIG.5Aillustrates a preform mold100having a rotatable core pin106arranged in a mold cavity104thereof, with a rotary drive unit108coupled to the rotatable core pin106. The preform mold100may be formed of separable halves101,102to enable removal of a preform following fabrication thereof. The mold cavity104includes a mouthpiece cavity portion104A, a tubular body cavity portion104B, and tip cavity portion104C each having different dimensions. The rotatable core pin106may include a tapered end portion107positioned within the tip cavity portion104C. As shown, the tubular body cavity portion104B comprises the longest portion of the mold cavity104, the mouthpiece cavity portion104A and the tubular body cavity portion104B include different but constant outer diameters (with the mouthpiece cavity portion104A including the smallest outer diameter of the mold cavity104), and the tip cavity portion104C includes a variable outer diameter. In use of the preform mold100, the separable halves101,102may be closed, molten thermoplastic material may be supplied to (e.g., injected into) the mold cavity104, and the core pin106may be rotated by operation of the rotary drive unit108while the thermoplastic material cools and solidifies in the mold cavity104. Thereafter, the separable halves101,102of the mold100may be separated from one another, and the preform may be removed from the core pin106by pulling the preform in a downward direction, and conveyed to a heating station.

FIG.5Bis a side elevation view illustration of a preform110producible with the preform mold100and rotatable core pin106shown inFIG.5B. The preform110includes a tubular body precursor portion114arranged between a mouthpiece precursor portion112and a tip precursor portion116, all surrounding a hollow interior118extending between a mouthpiece end111and a tip end117.

After fabrication of the preform110, the preform110may be heated to a softening temperature of the preform material, to prepare the preform110to be stretched and blown for formation of a pipette. In certain embodiments, such heating may be accomplished by positioning the preform110in or proximate to an infrared heating apparatus.FIG.5Cillustrates the preform110ofFIG.5Barranged within an infrared heating apparatus that includes infrared heating elements119A,119B, showing impingement of infrared radiation on the preform110.

FIG.5Dis a schematic side cross-sectional view illustration of a preform stretching apparatus120showing an elongated preform110′ (e.g., still in a heated state) after being subjected to a stretching operation by translation of a stretch rod122within an interior118′ of the elongated preform110′. The stretch rod122optionally includes a core123and a cladding124, and includes a tapered end125. Optionally, the core123may be arranged to rotate along a threaded surface internal to the cladding124to cause translation of the stretch rod122. In certain embodiments, the tapered end125has a shape corresponding to an interior taper of a tip portion116′ of the elongated preform110′ and/or corresponding to an interior taper of a transition region between the tip portion116′ and a tubular body portion114′, thereby allowing an interior of the elongated preform110′ to be plugged for blowing. The elongated preform110′ further includes a tubular body portion114′ and a mouthpiece portion112′. Translation of the stretch rod122is motivated by a stretch rod drive unit128. A chuck or clamp126is provided to immobilize the mouthpiece portion112′ as the stretch rod122is translated during the stretching operation.

FIG.5Eis a schematic side cross-sectional view illustration of the elongated, heated preform110′ (including a mouthpiece portion112′, tubular body portion114′, and tip portion116′) and stretch rod122ofFIG.5Dpositioned within a blow molding cavity134of a mold130. The mold130is composed of separable first and second mold halves131,132defining a molding surface135. A male receiving feature139may be provided at a bottom of the blow molding cavity134to assist in closing the interior of the elongated preform110′. As illustrated, the elongated heated preform110′ is in a state prior to blowing, involving the supplying of pressurized fluid into an interior thereof (e.g., through the stretch rod122) to cause the elongated preform110′ to radially expand and contact a molding surface135of the mold130. After the blowing operation is complete, the mold130may be opened by separating the mold halves131,132and removal of a resulting pipette from the stretch rod122.

FIG.5Fis a schematic cross-sectional view illustration of a stretch blow molded pipette140obtainable using the preform and apparatuses shown inFIGS.5A-5E, following stretching and blowing operations, and removal of the pipette140from the mold130. The pipette140includes a tubular body region144arranged between a mouthpiece region142and a tip region146, with a hollow interior150. A first abrupt transition region143is provided between the mouthpiece region142and the tubular body region144, and a second abrupt transition region145is provided between the tubular body region144and the tip region146; however, such transition regions143,145embody continuously uniform material without presence of any welded joints. Both an outer diameter and an internal bore148of the tip region146have a width that tapers with increasing proximity to a tip opening147. As shown, the tip region146includes an average wall thickness that exceeds a wall thickness of the tubular body region144, and the mouthpiece region142includes a smaller outer diameter than an outer diameter of the tubular body region144. The mouthpiece region142further includes a filter149arranged therein between an open mouthpiece end141and the tubular body region144. Although the mouthpiece region142is illustrated as having the same inner diameter as the tubular body region144, in certain embodiments, the mouthpiece region142may have a smaller inner diameter than an inner diameter of the tubular body region144.

FIGS.6-9embody tables providing calculated preform outer diameter, preform inner diameter, preform length, hoop ratio, axial ratio, and blow up ratio value ranges useful for producing stretch blow molded pipettes of multiple different volumes, with diameter and length values in inches. Hoop ratio is a ratio of the outer diameter of a tubular body region of a stretch blow molded pipette relative to the outer diameter of a tubular body region of a corresponding preform. Axial ratio is a ratio of length of a stretch blow molded pipette relative to the length of a corresponding preform. Blow up ratio is a product of hoop ratio and axial ratio.

FIG.6provides calculated value ranges useful for producing stretch blow molded pipettes of four different volumes having tubular body wall thickness dimensions consistent with conventional Costar® welded pipettes commercially available from Corning Incorporated (Corning, New York, USA), without using a spinning core pin during a preform fabrication step. The maximum outside diameter was calculated to enable orientation of polymer chains in a radial direction during blowing, without requiring use of a spinning core during preform molding to achieve biaxial orientation of the pipette material.

FIG.7provides calculated value ranges useful for producing pipettes of five different volumes, while using 50% less material than conventional Costar® welded pipettes, without using a spinning core pin during a preform fabrication step. As was the case withFIG.6, the maximum outside diameter was calculated to enable orientation of polymer chains in a radial direction during blowing, without requiring use of a spinning core during preform molding to achieve biaxial orientation of the pipette material. When compared withFIG.6,FIG.7shows that stretch blow molding a pipette requiring less material potentially opens the design range for molding of a preform, as evident by the expanded ranges for hoop ratio, axial ratio, and blow up ratio inFIG.7.

FIG.8provides calculated value ranges useful for producing stretch blow molded pipettes of five different volumes having tubular body wall thickness dimensions consistent with conventional Costar® welded pipettes, including use of a spinning core pin during a preform fabrication step. When comparingFIG.8withFIG.6, it is apparent that use of a spinning core enables a larger dimensional range of molded preforms, as evident by the expanded ranges for blow up ratio inFIG.8.

FIG.9provides calculated value ranges useful for producing pipettes of five different volumes, while using 50% less material than conventional Costar® welded pipettes, including use of a spinning core pin during a preform fabrication step. When comparingFIG.9withFIGS.7and8, it is apparent that use of a spinning core in combination with stretch blow molding of a pipette requiring less material enables an even larger dimensional range of molded preforms than either one of these circumstances alone, as evident by the expanded ranges for hoop ratio, axial ratio, and blow up ratio inFIG.9versusFIGS.7and8.

According to an aspect (1) of the present disclosure, a stretch blow molded pipette is provided. The stretch blow molded pipette comprises: a tubular body arranged between a tip region and a mouthpiece region; wherein the tip region comprises an average wall thickness that is greater than a wall thickness of the tubular body, and the stretch blow molded pipette is devoid of any joint (i) between the tubular body and the tip region, and (ii) between the tubular body and the mouthpiece region.

According to an aspect (2) of the present disclosure, the stretch blow molded pipette of aspect (1) is provided, wherein the tip region comprises an aperture having a substantially constant inner diameter.

According to an aspect (3) of the present disclosure, the stretch blow molded pipette of any of aspects (1)-(2) is provided, wherein the mouthpiece region comprises an average wall thickness that is greater than the wall thickness of the tubular body.

According to an aspect (4) of the present disclosure, the stretch blow molded pipette of any of aspects (1)-(3) is provided, comprising at least one of the following features (i) or (ii): (i) the mouthpiece region comprises an inner diameter that is smaller than an inner diameter of the tubular body; or (ii) the mouthpiece region comprises an outer diameter that is smaller than an outer diameter of the tubular body.

According to an aspect (5) of the present disclosure, the stretch blow molded pipette of any of aspects (1)-(4) is provided, wherein the tubular body, the tip region, and the mouthpiece region comprise a thermoplastic material.

According to an aspect (6) of the present disclosure, the stretch blow molded pipette of any of aspects (1)-(5) is provided, wherein the tubular body comprises biaxially oriented thermoplastic material.

According to an aspect (7) of the present disclosure, the stretch blow molded pipette of any of aspects (5)-(6) is provided, wherein the tubular body, the tip region, and the mouthpiece region comprise: crystalline polystyrene, poly(styrene-butadiene-styrene), polyethylene terephthalate, polypropylene, copolymers of any two or more of the foregoing polymers, or recycled streams of any one or more of the foregoing polymers.

According to an aspect (8) of the present disclosure, the stretch blow molded pipette of any of aspects (1)-(7) is provided, wherein the tubular body comprises a wall thickness in a range of from 0.25 mm to 0.6 mm.

According to an aspect (9) of the present disclosure, the stretch blow molded pipette of any of aspects (1)-(8) is provided, wherein the tip region comprises a substantially constant inner diameter, and comprises an outer diameter that increases with proximity to the tubular body.

According to an aspect (10) of the present disclosure, the stretch blow molded pipette of any of aspects (1)-(8) is provided, wherein the tip region comprises a non-constant inner diameter.

According to an aspect (11) of the present disclosure, the stretch blow molded pipette of any of aspects (1)-(10) is provided, wherein a region of greatest wall thickness of the stretch blow molded pipette is within the tip region, at or proximate to a transition between the tip region and the tubular body.

According to an aspect (12) of the present disclosure, a method for fabricating a pipette comprising a tubular body arranged between a tip region and a mouthpiece region is provided. The method comprises: fabricating a preform comprising a hollow tubular shape; heating the preform to within a softening temperature of a material of the preform; stretching at least a portion of the heated preform to form an elongated preform; blowing at least a portion of the elongated preform within a mold cavity by applying a pressurized fluid to an interior of the heated preform to cause the heated preform to expand into contact with a molding surface and assume a pipette shape; and cooling the blown and elongated preform.

According to an aspect (13) of the present disclosure, the method of aspect (12) is provided, wherein the stretching of at least a portion of the heated preform to form an elongated preform is performed while the heated preform is outside the mold cavity.

According to an aspect (14) of the present disclosure, the method of any of aspects (12)-(13) is provided, wherein the fabricating of the preform comprises: supplying moldable material in a molten state to a cavity of a preform mold; processing the moldable material by achieving relative rotation between (i) a core pin within the cavity of the preform and in contact with the moldable material and (ii) the perform mold; and cooling the moldable material to a solid state.

According to an aspect (15) of the present disclosure, the method of any of aspects (12)-(14) is provided, further comprising immobilizing a mouthpiece end of the preform prior to the stretching of at least a portion of the heated preform.

According to an aspect (16) of the present disclosure, the method of any of aspects (12)-(15) is provided, wherein the stretching of at least a portion of the heated preform utilizes a stretch rod comprising a tapered region having a shape matching an interior taper of a transition region between the tip region and the tubular body of the pipette.

According to an aspect (17) of the present disclosure, the method of any of aspects (12)-(16) is provided, further comprising one of the following steps (a) or (b) prior to the blowing of at least a portion of the elongated preform: (i) depositing ink on the molding surface, or (ii) inserting a label into the mold cavity.

According to an aspect (18) of the present disclosure, the method of any of aspects (12)-(17) is provided, wherein the heating of the preform to within a softening temperature of a material of the preform comprises impinging infrared radiation on the preform.

According to an aspect (19) of the present disclosure, a system for fabricating a pipette comprising a tubular body arranged between a tip region and a mouthpiece region by a stretch blow molding process is provided. The system comprises: a first mold defining a preform mold cavity configured to permit molding of a hollow preform therein; a preform stretching apparatus comprising a stretch rod positionable within an interior of the hollow preform and coupled with a stretch rod drive unit that is configured to move the stretch rod within the interior of the hollow preform to form an elongated preform; a second mold defining a blow molding cavity configured to contain at least a portion of the elongated preform while pressurized fluid is supplied to an interior of the elongated preform to cause the elongated preform to radially expand and contact a molding surface of the second mold.

According to an aspect (20) of the present disclosure, the system of aspect (19) is provided, wherein the first mold is configured to receive a core pin within the preform mold cavity, and the system further comprises a rotary drive unit configured to achieve relative rotation between the core pin and the first mold during molding of the hollow preform within the first mold.

According to an aspect (21) of the present disclosure, the system of any of aspects (19)-(20) is provided, being configured to enable movement of the stretch rod within the interior of the preform to form the elongated preform while the preform is outside the blow molding cavity.

According to an aspect (22) of the present disclosure, the system of any of aspects (19)-(21) is provided, further comprising an infrared heating element configured to heat the preform to a softening temperature of a material of the preform prior to movement of the stretch rod within the interior of the hollow preform to form the elongated preform.

According to an aspect (23) of the present disclosure, the system of any of aspects (19)-(22) is provided, further comprising a chuck or clamp configured to immobilize a mouthpiece end of the preform during movement of the stretch rod within the interior of the hollow preform to form the elongated preform.

According to an aspect (24) of the present disclosure, the system of any of aspects (19)-(23) is provided, wherein the stretch rod comprises a tapered region having a shape matching at least one of (i) an interior taper of the tip region, or (ii) an interior taper of a transition region between the tip region and the tubular body of the pipette.

In further aspects of the disclosure, it is specifically contemplated that any two or more aspects, embodiments, or features disclosed herein may be combined for additional advantage.

As used herein, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a “notch” includes examples having two or more such “notches” unless the context clearly indicates otherwise

The term “include” or “includes” means encompassing but not limited to, that is, inclusive and not exclusive.

“Optional” or “optionally” means that the subsequently described event, circumstance, or component, can or cannot occur, and that the description includes instances where the event, circumstance, or component, occurs and instances where it does not.

Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is no way intended that any particular order be inferred. Any recited single or multiple feature or aspect in any one claim can be combined or permuted with any other recited feature or aspect in any other claim or claims.

It is also noted that recitations herein refer to a component being “configured” or “adapted to” function in a particular way. In this respect, such a component is “configured” or “adapted to” embody a particular property, or function in a particular manner, where such recitations are structural recitations as opposed to recitations of intended use. More specifically, the references herein to the manner in which a component is “configured” or “adapted to” denotes an existing physical condition of the component and, as such, is to be taken as a definite recitation of the structural characteristics of the component.

While various features, elements or steps of particular embodiments may be disclosed using the transitional phrase “comprising,” it is to be understood that alternative embodiments, including those that may be described using the transitional phrases “consisting” or “consisting essentially of” are implied.