GB2026995A

GB2026995A - Closure Caps

Info

Publication number: GB2026995A
Application number: GB7926411A
Authority: GB
Original assignee: Coulter Electronics Inc
Current assignee: Coulter Electronics Inc
Priority date: 1978-08-01
Filing date: 1979-07-30
Publication date: 1980-02-13
Also published as: FR2432449A1; DE2930828A1; GB2026995B; CA1151598A; FR2432449B1

Abstract

A reusable closure cap for sealing a vial comprises a rigid tubular screw- type cover (10) having as an integral part thereof a relatively soft, highly elastic stopper (12) bonded at its top to the interior of the closed top end of the tubular cover. The elastic stopper has its top and a lower portion both larger in diameter than the inside diameter of the top opening of the vial (16), so as to enable an air and liquid tight seal. The bonding of the stopper to the cover and the sealing of the vial are both accomplished by: seating the stopper into the top of the vial, applying an adhesive (14) to the top of the stopper, and screwing down the cover over the vial and stopper. An embodiment of the stopper and the sealing method is adapted for freeze- dry technology. <IMAGE>

Description

SPECIFICATION Closure Cap This invention is concerned with closure caps for use on vials in the medical and biochemical art fields.

An important requirement in the use of such caps is that they be capable of tightly sealing the vials from bacterial and other contaminants which may enter the vial from the external environment, and that they be reusable until the contents of the vial are entirely depleted.

Known types of vial closure caps suffer from problems. One such known closure cap makes use of a rubber plug stopper which after insertion into the open end of the vial has its upper portion completely covered and surrounded by a thin aluminium sheath. The top of the aluminium sheath and a small portion of the surrounding aluminium skirt are scored to enable the insertion of a fingernail to thereby tear the thin aluminium sheath and remove it from the rubber stopper. In practice, the aluminium sheath does not always completely separate from the rubber st er and the technician often suffers finger cuts front the sharp edges of the aluminium residue which surrounds the stopper.Other problems with this particular type of closure cap are: the fingernail inserted into the scored portion of the aluminium sheath may break, and the removal of the rubber plug stopper sometimes causes the liquid contents (often a blood solution) of the vial to splash onto the person opening the vial.

Another known closure cap is described in U.S.

Patent 3,540,612 granted to William T. Brady, November 17, 1970. This patent discloses a closure cap having a frustoconical section connected to a closed end plug section to form a one-piece cap. The plug section has a bead thereon removed from the distal end thereof. All parts of this particular cap are made of the same deformable material which material bulges when the cap is tightened on the vial. Although the patent fails to describe the particular material from which the entire cap is made, it is quite clear that it is a plastic, such as a copolymer, which deforms partially plastically and partially elastically, as evidenced by the commercially available bottle caps incorporating the patented invention.Disadvantages of this known cap are: The torque required to open and close the bottle cap during repeated uses of the cap tends to cause the deformable plastic material to retain the shape into which it has been deformed once it has been initially used, thereby interfering with a perfect seal upon re-use of the cap. Since the screw-type cover part and the closed end plug of the one-piece cap are made of the same deformable material, the screw threads of the cover tend to deform permanently upon repeated threading and rethreading of the cap on the bottle until finally tightening of the cap on the bottle does not produce sufficient downward pressure to assure a proper air and liquid-tight seal with the bottle.The space between the bead and the bottom of the plug constitutes a blood catching intersection area which promotes clotting and coagulation of the blood, thereby interfering with accurate repeatable instrument counter readings and measurements of the blood solution until the vial contents are entirely depleted.

According to the invention there is provided a method of sealing a vial, capable of holding a liquid, with a reusable closure cap consisting-of a rigid screw-type cover part which surrounds and is bonded in its interior to the top of a highly elastic stopper part, which comprises: seating the elastic stopper into the open end of said vial, applying a thrusting force to the top of said stopper part to cause it to enter the open end of said vial a sufficient distance to tightly seal the contents of said vial, applying a strong-bonding adhesive material, to one of said parts in an area between the top of said elastic stopper part and the uppermost interior portion of the rigid screw type cover part, and then placing said cover part over and surrounding said stopper part and the adjoining end of said vial, so that said cover part firmly contacts the top of said stopper part and, with said adhesive material, produces a permanent strong bond between cover and stopper.

The invention also provides a method of manufacturing a reusable closure cap for sealing a vial having an exteriorly threaded open end, which comprises selecting a plug-type highly elastic, liquid impermeable stopper having a closed end of such lateral dimension as to extend across and beyond the open end of said vial and a bottom portion having a lateral dimension below said closed end which in its unflexed condition is slightly larger than the lateral dimension of the opening of said vial, applying a thrusting force to said stopper to seat the stopper into the open end of said vial to thereby effect a liquid and air-tight seal with said vial, selecting a rigid interiorly threaded cover closed at one end and whose threads are adapted to mesh with the exterior threads on said open end, applying a strong bonding adhesive to an area between the exposed closed end of said stopper and the interior of the closed end of said cover, placing said cover over and surrounding said neck and surrounding said stopper, and then turning said cover on the threads of said neck until said cover firmly engages the closed end of said stopper, whereby said cover and stopper become an integrally bonded unit which constitutes a reusable closure cap.

The invention further provides a reusable closure cap for sealing a vial which has an exteriorly threaded open end, comprising as a single integral unit a rigid tubular cover of one kind of material interiorly threaded for registering with the threads on said via 1,and a plug-type stopper of a different kind of material which is highly elastic, relatively soft, and has a closed end of such lateral dimension as to extend across and beyond the open end of said vial and a bottom portion having a lateral dimension below said closed end which in its unflexed condition is larger than the lateral dimension of the open end of the vial, said stopper being bonded at the central portion of its closed end to the top of said rigid cover in its interior, said stopper serving to seal the contents of said vial and having structural ability to stretch under relatively low stress and to snap rapidly back to its original shape upon release of stress.

The closure cap embodied hereinafter overcomes the aforesaid disadvantages of the known vial caps. Broadly stated, the embodied cap is a rigid screw-type tubular cover permanently bonded in its interior as a single integral unit to a relatively soft highly elastic elastomer material. The term "elastomer" used herin is a material which at room temperature stretches under low stress to at least twice its length and snaps back to its original length upon release of the stress. This term is deemed to include natural and synthetic rubber or any "rubber like" material such as soft flexible plastics which are highly elastic and capable of rapid elastic recovery upon the release of stress or pressure.The cap, in one embodiment set forth herein satisfies the important requirement that there must be precision and accuracy of measurements during repeated uses of a vial containing a blood solution until the entire contents are used up. The blood solution in the vial must be free of contaminants at all times. To assure this desideratum, the closure cap embodying the invention always provides an effective air and liquid-tight seal with the vial between repeated usages of the vial, and is so constructed and arranged that there exists a smooth flow of blood solution over the interior of the vial during a rocking motion of the vial without causing clotting or coagulation of the blood on the interior of the cap.The relative ease in removing the cap from the vial and resealing the vial without causing splashing of the liquid contents or deterioration in the sealing performance of the cap is an additional advantage.

The rocking motion referred to above is a mixing action to assure homogeneity of the blood solution in the vial before it is used each time.

Tiny glass beads or ball bearings may be introduced into the vial to promote mixing of the blood solution during the rocking motion.

An embodiment of the closure cap, as will be described, is for use with a vial having a liquid solution, for example, blood, and comprises a rigid tubular cover of plastic material closed at one end and threaded in its interior in the manner of a screw-top cover for registration with the threads on the exterior of the vial. A highly elastic stopper is bonded to the interior of the closed end of the rigid threaded tubular cover by a pressure sensitive, strong-bonding, fast-acting adhesive so that the cover and stopper form an integral unit.

The highly elastic elastomer stopper is designed to enter the open end of the vial to provide an air and liquid-tight seal with the walls of the vial. The stopper is arranged coaxially with the center of the rigid cover and has a tapered portion with a rounded edge to enable effective insertion into the open end of the vial in response to a downward pressure thereon resulting from tightening of the cap on the vial. This downward pressure is achieved by turning or twisting the cap onto the open end of the vial so that the threads in the cover engage the threads on the vial to the fullest extent. The bottom of the stopper is concave to enable the blood solution contents of the vial to flow smoothly thereover and back into the vial during the rocking motion of the vial.The smooth concave surface prevents the blood solution from collecting at points of contact between stopper and vial and causing undesired clotting or coagulation of the blood. Stated another way, the stopper embodying the invention is designed to minimize or eliminate virtually entirely blood retaining, catching intersection areas.

An important characteristic of the relatively soft elastic stopper used in the closure cap of the present embodiments is its ability always to retain its original shape despite repeated useage of the closure cap. This stopper will become deformed when pressure or force is applied to it and then snap back rapidly to its original shape when the pressure or force is removed, in the manner characteristic of the quality of a rubber band which has not been stretched beyond its elastic limit A preferred form of the relatively soft highly elastic stopper used in the practice of the set forth embodiments is one which has an endless groove in the top thereof to allow any undesired excess of glue or adhesive applied during the bonding process of rigid screw-type cover and elastic stopper to flow into the groove, thereby preventing the glue or adhesive from running over the top of the stopper and into the thread area between the closure cap and the bottle over which the closure cap is placed. Although the endless groove is preferred, it may be replaced by a series of groove-like indentations around the top of the stopper without departing from the spirit and scope of the teachings of the purpose of the groove.

The closure cap of the embodiment of the invention has been satisfactorily used with a Coulters Hematology Reference Control constituting a vial containing a blood solution for monitoring the precision and accuracy of the Coulter Counter measurements or determinations of the following: White Cell Counts, Red Cell Counts, Hemoglobin, Mean Corpuscular Voiume, Hematocrit, mean Corpuscular Hemoglobin, and Mean Corpuscular Hemoglobin Concentration. The hematology reference control is made from human blood to which are added fixed erythrocytes to stimulate leukocycles. One such control is commercially sold under the trademark 4C Coulter Electronics, Inc., of Hialeah, Floridaa...

Another closure cap, which will be described, is designed for use with a vial the contents of which are to be subjected to a freeze-dry operation. Here again, there is provided a relatively soft highly elastic stopper of rubber or a flexible plastic of "rubber iike" consistency which is bonded at its top by relatively fast-acting, pressure-sensitive, strong-bonding material to the interior of a screw top cover made of rigid plastic material. The stopper of this embodiment has a tapered portion consisting of a plurality of equal-length spaced segments surrounding a hollow interior. The segments are arcuate in shape. Each segment is separated from its adjacent segment by a slot which is in fluid-free communication with the hollow interior, and is provided with a pair of spaced rubber ridges along its length. The ridges on all segments lie on concentric circles.The continuity of each circle of ridges is interrupted by the aforesaid slots. The purpose of the ridges is to enable the stopper to seat itself partially into the vial during a freeze-dry operation on the vial contents, before the vial contents are completely freeze-dried and before the highly elastic stopper is pushed further into the vial to provide an airtight seal and then subsequently bonded to the screw top cover. here again, the stopper is made of highly elastic rubber or "rubber like" plastic material as is the stopper of Figs. 1, 2 and 3. A more detailed description of this operation appears hereinafter. The stopper of all embodiments serves as a plug-type stopper.

By way of example only, illustrative embodiments of the invention now will be described with reference to the accompanying drawings, in which: Fig. 1 is a vertical section through the closure cap of one of the embodiments, showing the relatively soft highly elastic stopper within and secured to the surrounding rigid cover as an integral unit therewith; Fig. 2 is a vertical section through the highly elastic stopper of Fig. 1; Fig. 3 is a preferred form of stopper and is a modification of the stopper of Figs. 1 and 2 by including an endless circular groove in the top of the stopper.

Fig. 4 is an exploded view in perspective of the various parts of the closure cap of Fig. 1, using the stopper of Fig. 3, in relation to a known screw-cap type of glass vial with which the closure cap embodying the invention may be used; Fig. 5 is a vertical section of a screw-cap type vial showing an embodiment of the closure cap in air and liquid-tight sealing relation with the vial.

The highly elastic stopper is shown partly in section and partly in perspective; Fig. 6 is a vertical section through the closure cap of another cap of another embodiment particularly designed to permit a freeze-dry process to be applied to the vial contents. The highly elastic stopper is shown partly in section and partly in perspective; Fig. 7 is a perspective view of the highly elastic stopper of Fig. 6; Fig. 8 is a bottom view of the stopper of Figs. 6 and 7: Fig. 9 is a view partly in section and partly in perspective of the closure cap of Fig. 6 inserted partially into the open neck of a screw-cap type of vial, in the position the cap occupies during the freeze-dry process; and Fig. 10 shows the closure cap of the embodiment of Figs. 6 and 9 tightly screwed to the top of the vial.

In the figures, the same parts have the same reference numerals, and equivalent parts carry prime designations. The drawings are exaggerated in size in the interest of clarity. The dimensions given in Figs. 1, 2, 3 and 6 are accurately representative of the closure caps successfully constructed and commercialized.

The closure cap embodiment hereinafter set forth in Figs. 1 to 5 inclusive comprises a rigid plastic cover 10 of the screw top type made from a plastic material, for example, a phenolic plastics material to the interior of which there is securely fastened a highly elastic stopper 12. Both rigid cover 10 and elastic stopper 1 2 form a single integral unit bonded together by a pressure sensitive, strong-bonding, fast-acting, adhesive or glue 14. The adhesive 14 may be ethyl, cyanocrylate. One example of such strong bonding glue is commercially sold under the trademark "SUPER GLUE" and is distributed by Loctite Corp. of Newington, Connecticut.

The rigid cover 10 is tubular in configuration with a smooth flat top and helically wound interior threads, as shown, adapted to engage the threads on the top portion of the vial 1 6. Vial 16 is typical of any small bottle having a reduced neck portion threaded exteriorly to accept the threads on the cover 10 when the cap is tightened on the vial by a twisting motion. The exterior circular surface of the rigid cover is preferably knurled or provided with numerous equally spaced serrations as shown, to enable easy grasping of the cover. The exterior top surface of the rigid cover need not be flat.

The highly elastic stopper 1 2 is relatively soft and made of an elastomer such as natural or synthetic type rubber or a combination of natural and synthetic type rubber, or a "rubber like" highly elastic soft flexible plastic such as polyvinyl chloride (PVC) or polyethylene-ethylene vinyl acetate copolymers. The material from which the stopper is made must be highly elastic, able to stretch under low stress and snap back to its original shape upon release of stress. The PVC may be treated with an additive to provide the desired elastic properties. The synthetic type rubber can, for example, be neoprene or silicon rubber. The highly elastic stopper has a smooth flat top area to which the glue 14 is applied for attachment to the interior of the rigid cover 10, as explained in more detail hereinafter.Stopper 12 is devoid of any relatively hard or stiff plastic material and has such high elasticity that it always returns very rapidly to its orginal size and shape shown in Figs. 1 to 5 after repeated flexing and stretching during usages of the cover cap of the invention. The central portion of the stopper 12 facing the open end of the glass vial is provided with a smooth concave hollow area 1 8 to enable the liquid solution, such as blood, in the vial to flow thereover during agitation of the contents of the vial without collecting any part of the solution on its surface. The smoothly rounded ends 20 of the concave hollow area 18 promote the mixing action of the blood and aid in minimizing or eliminating virtually entirely blood retaining, intersection areas.The tiny glass beads or ball bearings hereinbefore mentioned, contained in the vial, roll over the rounded ends 20 and into the concave interior 18 and then back into the vial as the vial is rocked. The stopper 12 is fluid impermeable and its flat top has a lateral dimension greater than the inside diameter of the open end of the vial.

A protruding circular lip or shouider 22 of the stopper 12 engages the interior of the neck of the vial 16 when the closure cap is screwed down on the vial, as shown in Fig. 5, and provides an air and liquid-tight seal. Figs. 1, 2 and 3 illustrate how the lip extends outwardly when the closure cap is removed from the vial; while Fig. 5 shows how the lip is flexed or squeezed against the interior of the neck of the vial when the closure cap is tightened down on the vial. The bottom portion of the stopper 1 2 between circular lip 22 and the rounded ends 20 is tapered to permit easy insertion of the stopper into the open end of the neck of the vial. An indented portion 11 between the circular lip 22 and the top portion of the stopper 12 provides space into which the lip can flex in the sealing position of Fig. 5.The surface of the stopper can be treated with liquid silicon to provide lubrication properties. This is done by placing numerous of these embodied stoppers in a tumbling machine and introducing therein liquid silicon in the approximate ratio of a couple of ounces of silicon to one hundred thousand stoppers.

The elastic stopper 12' of Figs. 3, 4 and 5 is provided with an endless groove 1 3 to allow any undesired excess of glue 14 applied during the bonding process of rigid screw-type cover and elastic stopper to flow into the groove, thereby preventing the glue from running over the top of the stopper and into the threaded area between the closure cap and the bottle over which the cap is placed. This groove can be of any desired depth in the top of the stopper provided that the groove does not penetrate into the indent portion 11.

An important aspect of the embodied closure cap is that it has a hard rigid material for its cover, where it is needed, and a soft, highly elastic material for its stopper, as is required for the sealing operation; as distinguished from a closure cap made of identical materials for both cover and stopper.

In the manufacturing operation of producing the closing cap of Figs. 1 to 5 inclusive, the highly elastic stoppers are sterilized in an autoclave before being moved into a glove box. The interior of the glove box is a sterile environment due to a flow of sterile air therethrough. Hand manipulation in the steril box is achieved by an operator with sterile gloves affixed to sealed openings in the box into which the operator inserts her hands. The steril vials are moved in trays down the sterile box and the blood solutions inserted into the vials. The operator then selects a stopper, places it over the open neck of the vial and by a single downward motion of a finger tamps the stopper into the vial to produce an air and liquid-tight seal. At this point in the operation there is no need to hold the vial.Thee contents of the vial are, at this point, completely sealed from outside contamination. The sealed vials are then moved to a station outside the sterile box and a drop of pressure sensitive, strong-bonding, fastacting glue or adhesive 14, such as ethyl cyanocrylate material, is placed on top of the pure rubber stopper 12. The glue drop can be approximately 1 OOth of a ml

Excess glue will flow into groove 1 3 of the elastic stopper. The open end of the rigid plastic cover is then immediately placed over the stopper and screwed onto the threads on the vial to the fullest extent, thereby causing the smooth interior of the top portion of the rigid plastic cover to firmly engage the top of the rubber stopper.The pressure-sensitive, strong-bonding glue spreads and bonds the stopper and cover into a single integral closure cap unit such that unscrewing the rigid cover results in the removal of the highly elastic rubber stopper from the vial. The cover cap of Figs. 1 to 5 can now be used repeatedly to achieve firm air and liquid-tight sealing of the liquid contents of the vial merely by turning the rigid cover on the vial in the proper direction.

The closure cap of the embodiment of Fig. 6 differs from that of Fig. 1 primarily in the structure of the highly elastic stopper. Here again, as in Fig.

1, the stopper 24 is securely bonded by a drop of strong-bonding, fast-acting, pressure-sensitive glue to the interior top portion of the rigid plastic cover 10' so that the rigid cover 10' and the highly elastic stopper 24 form a single integral unit. Although not shown in Figs. 6 to 10, the elastic stopper 24 can be provided with a circular groove in the top thereof in the manner shown in Figs. 3, 4 and 5 to allow undesired excess glue to flow therein during the bonding process of screw type cover and stopper.

The stopper 24 of Figs. 6 to 10 is designed for use in a freeze-dry operation on the contents of vial 1 6. As shown most clearly in Figs. 6 and 7, the stopper 24 has its lower part divided by three equally spaced slots 26 into three flexible equal length segments 28. These segments 28 surround an interior hollow space 30 which extends from the top of the stopper to its bottom and is longer than the slots 26. Each segment 28 is provided with two spaced ridges 32 and 32' of the same elastic material as the rest of the stopper. The lower portions of the segments 28 are tapered inwardly toward the center, as shown.

The ridges 32 and 32' form concentric circles which are interrupted by the equally spaced slots 26.

It should be noted from Fig. 6 that the open end of the tubular interiorly threaded rigid plastic cover 10' is flush with the tapered tip of the highly elastic stopper 24; whereas, in the embodiment of Fig. 1, the rigid plastic cover 10 extends beyond the bottom part of the stopper 1 2. Variations in length of the rigid plastic cover are permissible with due regard to the sealing functions to be achieved and the dimensions of the neck portion of the vial 16.

The operating steps which result in the freezedry process, the sealing of the vial, and the bonding of the highly elastic rubber stopper and the rigid plastic cover as a single integral will now be given.

The vial with its liquid contents appears before the operator in a clean but not necessarily a sterile environment. The operator inserts-the stopper 24 partially into the open neck of the vial 1 6 until the stopper rests on its lowermost ridge 32', as indicated in Fig. 8. The vial along with many hundreds or thousands of similar vials, also provided with identical partially seated stoppers, is placed in the freeze-dry chamber in which the temperature and vacuum are controlled. Due to the partial seating of the rubber stopper 24 in the neck of the vial 16 there is fluid flow communication between the freeze-dry chamber and the interior of the vial through the slots 26 and the centrally positioned hollow space 30. The vacuum in the freeze-dry chamber reduces the frozen contents of the vial to powder or granules.

Observation of the condition of the vial contents can be made through windows in the freeze-dry chamber.

After the freeze-dry operation is completed and while the stopper is partially in place a shelf or similar object within the freeze-dry chamber descends to fully and completely seat the highly elastic stoppers on the necks of the vials in the manner indicated by the position of the stopper in Fig. 10, to thereby tightly seal the powdered contents within the vial from the outside atmosphere. The elastic ridges 32 are squeezed against the interior neck part of the vial to aid in sealing the vial. The sealed vials with the stoppers in place are then removed from the drying chamber into a clean area.The operator now places a drop of pressure-sensitive, strongbonding, fast-acting glue on the top of each stopper after which the rigid plastic screw-type cover is immediately placed over the stopper and tightened over the neck of the vial so as to bond the stopper to the interior top portion of the rigid cover as indicated in Fig. 10. This last step is similar to that hereinbefore described to form the bond between the rigid cover and the stopper of the embodiment of Fig. 1. The cover cap of Fig.

10, like that of Fig. 1, can be repeatedly used merely by turning the rigid cover which carries with it, as an integral unit thereof, the highly elastic sealing stopper.

In closure cap embodiments of the invention constructed and satisfactorily tested, the stopper was made of natural rubber which when subjected to three hundred percent (300%) of elongation indicated a stress reading of twelve hundred pounds per square inch (1200 psi).

Although such a reading is preferred, the range of acceptable material for the highly elastic stopper may be from 300 psi up to 2500 psi. This range is not as great as it may seem, since it is not strictly linear and the higher numbers represent material that is harder to stretch as well as reflecting the fact that the material has a greater tenacity in retaining its original shape when subjected to stress as well as returning to its original shape when stress is removed. In contrast, normal plastics, such as the rigid cover of the closure cap embodying the invention, has a modulus of elasticity approximating 200,000 psi for the same degree of elongation.

Claims

1. A method of sealing a vial, capable of holding a liquid, with a reusable closure cap consisting of a rigid screw-type cover part which surrounds and is bonded in its interior to the top of a highly elastic stopper part, which comprises: seating the elastic stopper into the open end of said vial, applying a thrusting force to the top of said stopper part to cause it to enter the open end of said vial a sufficient distance to tightly seal the contents of said vial, applying a strong-bonding adhesive material to one of said parts in an area between the top of said elastic stopper part and the uppermost interior portion of the rigid screwtype cover part, and then placing said cover part over and surrounding said stopper part and the adjoining end of said vial, so that said cover part firmly contacts the top of said stopper part and, with said adhesive material, produces a permanent strong bond between cover and stopper.

2. A method of claim 1, wherein the permanent bonding of said stopper to the rigid screw-type cover part in the interior thereof is the result of turning the cover part over the aforesaid end of said vial until the cover part firmly engages the stopper.

3. A method according to claim 1 or 2 in which said step of seating comprises: partially seating said highly elastic stopper into the open end of said vial to permit vacuum suction of liquid contents of the vial to occur during a freeze-dry process, completing the freeze-dry process in a freeze-dry chamber under suction, whereby the liquid contents is reduced to powder form, then applying said thrusting force to the top of said elastic stopper to force said stopper further into said vial and thereby produce an air-tight seal with the wall of said vial while the vial is still under suctionsin said chamber.

4. A method according to any one of claims 1 to 3 which includes the steps of: employing a sterile stopper, seating the sterile stopper into the open end of said vial while said vial is within a sterile environment, and advancing the sealed vial to an area outside said sterile environment before applying said adhesive material.

5. A method of manufacturing a reusable closure cap for sealing a vial having an exteriorly threaded open end, which comprises selecting a plug-type highly elastic, liquid impermeable stopper having à closed end of such lateral dimension as to extend across and beyond the open end of said vial and a bottom portion having a lateral dimension below said closed end which in its unflexed condition is slightly larger than the lateral dimension of the opening of said vial, applying a thrusting force to said stopper to seat the stopper into the open end of said vial to thereby effect a liquid and air-tight seal with said vial, selecting a rigid interiorly threaded cover closed at one end and whose threads are adapted to mesh with the exterior threads on said open end, applying a strong bonding adhesive to an area between the exposed closed end of said stopper and the interior of the closed end of said cover, placing said cover over and surrounding said open end and surrounding said stopper, and then turning said cover on the threads of said vial until said cover firmly engages the closed end of said stopper, whereby said cover and stopper become an integrally bonded unit which constitutes a reusable closure cap.

6. A reusable closure cap for sealing a vial which has an exteriorly threaded open end, comprising as a single integral unit a rigid tubular cover of one kind of material interiorly threaded for registering with the threads on said vial, and a plug-type stopper of a different kind of material which is highly elastic, relatively soft, and has a closed end of such lateral dimension as to extend across and beyond the open end of said vial and a bottom portion having a lateral dimension below said closed end which in its unflexed condition is larger than the lateral dimension of the open end of the vial, said stopper being bonded at the central portion of its closed end to the top of said rigid cover in its interior, said stopper serving to seal the contents of said vial and having structural ability to stretch under relatively low stress and to snap rapidly back to its original shape upon release of stress.

7. A closure cap according to claim 6 wherein said closed end of said stopper forms a flat top area and said bottom portion includes a coaxially positioned tapered portion, said tapered portion being adapted to enter the open end of said vial and provide a liquid and air tight seal for the contents of said vial.

8. A closure cap according to claim 6 or 7, wherein there is a circular indented portion in said elastic stopper between said bottom portion and said closed end.

9. A closure cap according to any one of claims 6 to 8, wherein said bottom portion is closed and is formed with a concave surface area facing the open end of said vial to enable the liquid contents of said vial to enter therein and exit smoothly therefrom when said vial is shaken.

10. A closure cap according to any one of claims 6 to 9, wherein said bottom portion of the stopper has a plurality of spaced slots therein extending the length thereof to provide a plurality of highly elastic segments surrounding a centrally positioned hollow interior.

11. A closure cap according to claim 10, wherein there are provided spaced ribs on said segments along the widths thereof, to enable said stopper to be initially positioned partially into the vial while enabling fluid communication between the interior and the outside of said vial by way of said slots.

12. A closure cap according to any one of claims 6 to 11, wherein the top of said highly elastic stopper is provided with a groove located near the peripheral bounds thereof to prevent bonding material to go therebeyond.

13. A closure cap according to any one of claims 6 to 12, wherein said highly elastic stopper is rubber which stretches approximately three hundred percent under a stress of approximately 1200 pounds per square inch.

14. A closure cap according to any one of claims 6 to 13, wherein said highly elastic stopper is characterized by its ability to stretch under a stress in the range of approximately 300 psi up to 2500 psi and to rapidly return to its original shape upon release of said stress.

1 5. A method of sealing a vial, substantially as herein described with reference to and as illustrated by the accompanying drawings.

16. A method of manufacturing a reusable closure cap, substantially as herein described with reference to and as illustrated by the accompanying drawings.

1 7. A reusable closure cap substantially as herein described with reference to and as illustrated by the accompanying drawings.

18. A closure cap as claimed in claim 17 substantially as herein described with reference to and as illustrated by Figures 1 and 2 of the accompanying drawings.

19. A closure cap as claimed in claim 1 8 but modified substantially as herein described with reference to and as illustrated by Figure 3 of the accompanying drawings.

20. A closure cap as claimed in claim 1 7 substantially as herein described with reference to and as illustrated by Figures 6, 7 and 8 of the accompanying drawings.

21. A vial provided with a closure cap as claimed in any of claims 6 to 14 or 17 to 20.

22. A vial sealed by a method as claimed in any of claims 1 to 4 or 15.

23. A closure cap, the cap being the product of either claim 5 or 16.