CA1151598A

CA1151598A - Closure cap

Info

Publication number: CA1151598A
Application number: CA000332789A
Authority: CA
Inventors: Robert R. Burnett; John W. Box
Original assignee: Coulter Electronics Inc
Current assignee: Coulter Electronics Inc
Priority date: 1978-08-01
Filing date: 1979-07-30
Publication date: 1983-08-09
Also published as: FR2432449B1; GB2026995B; GB2026995A; FR2432449A1; DE2930828A1

Abstract

ABSTRACT
A reusable closure cap for sealing a vial, a method of making such closure cap, and methods of sealing a vial with such closure cap. The closure cap comprises a rigid tubular screw-type cover having as an integral part thereof a relatively soft, highly elastic stopper 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, 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 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.

Description

~lS98 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 bacteria and other contaminants which may enter the ~ial from the external environment, and that they be reusable until the contents of the vial are entirel~ 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 aluminum sheath. The top of the aluminum sheath and a small portion of th~ surrounding aluminum skirt are scored to enable the insertion of a fingernail to thereby tear the thin aluminum sheath and remove it from the rubber stopper. In practice, the aluminum sheath does not always completely separate from the rubber stopper and the technician o~ten suffers finger cuts from the sharp edges of the aluminum residue which surrounds the stopper. Other problems with this particular type of closure cap are: the fingernail inserted into the scored por-tion of the aluminum 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 grantecl to William T. Brady, November 17, 1970. This patent discloses a closure cap having a frustoconical section connected ~e ~5~S98 to a ctosed end plug section to forn~ a ore~iece cap. The ptug section has a bead thereon removed from the dîstal end thereof. All parts of this particutar cap are made of the same deformable material which material bulges when the cap is tightened on the vial.
Atthough the patent fails to describe the particutar material From whid~ the entire cap is made, it is quite clear that it is a plastic, - such as a cGpolyrner, which de~orrns partially plastically and partiaily etastically, as evidencsd ~y the commerciatly availabte bottte 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 deformabte plastic material to retain the shape into which it has been deformed once it h~s been initialty used, thereby interfering with a perfect seat upon rs--use of the cap. Since the screwtype cover part and the closed end plug of the one-piece cap are made of the same deformabte material, the screw threads of the cover tend to deform permanently upon repeated threading and rethreading of the cap on the bottte untit finally tightening of the cap on the bottte does not pro-duce sufr~ciert dowr,ward pressure to assure a proper air and liquid-tight seal with the bottla. The spacs between the bead and the botton~ of the plug constitutes a blood catching inter~ection area which promotes ctotting and coagutation of the btood, thereby interfering with accurate repeatabte instrument counter readings and measure-ments of the blood sotution untit the vial contents are entirely depteted.

According to the invention there is provided a method of sealing a vial, capable of holdin~ a liquid, with a reusable closure cap consisting of a rig;d screw-type cover part which surrounds and is bonded in its interior to the top of ~ h;ghly 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 di~ension 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 l598 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 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.

`~5~5~8 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 herein 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 accur-acy 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 of 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 vlal 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 re-sealing the vial without causing splashing of the liquid contents or deterioration in the sealing performance of the cap is an additional advantage~

~5~59~
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 bea~ings may be introduced into the vial to promote mixing of the blood solu-tion 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 providP 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 extenk. 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 clot-ting or coagulation of the blood. Stated another way, thestopper of the invention is designed to minimize or eliminate entirely blood retaining, catching intersection areas.

~51598 An important characteristic of the relati~ely soft elastic stopper used in the closure cap of the present embodi-ments is its ability always to r~tain its original shape des-pite repeated useaye 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 preferrsd, 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 this embodiment of the invention has been satisfactorily used with a Coulter ~ 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 Volume, 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 commerically sold under the trademark 4C ~ Coulter Electronics, Inc., of Hialeah, s9~
Florida.
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 like" 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 acruate 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 segmants 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 air-tight 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.
~ 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 accompany-ing drawings, in which:

Fig. t is a vertical section through the closure cap of one of the embodiments, showir,g the relatLvely soflc highly elastic stopper within and secured to the surroundlng rigid cover as an Lntegral unit therewith;
Fig. 2 ts a vertical section through the hlghly elastic stopper of Fig. 1;
Fig, 3 is a preferred form of stopper and is a modification of the stopper of Figs. t and 2 by including an endless circular groove in the top of the stoppsr.
Fig. 4 is an exploded view in perspective of the various parts oF the closure cap of Fig, t, using the stopper of Fig~ 3, in relation to a ',~nown screw--cap type of gtass vial with which the closure cap of the invention may be used;
- -- Fig, 5 is a vertical section oF a scre~ap 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;
~ig, 6 is a vertical section through the closure cap of another cap of another embodiment particutarly designed to perrnit 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 his;hly 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 c~f Fig. 6 irserted partiatly into the open neck of a screw-cap type of vial, in the position the cap occupies during the Freeze~ry process; and ~L~ 5 9 8 Fig. 10 shows the closure cap o~ the e~bodiment of Figs. 6 and 9 tightly screwed to the top of the vial.
I~ the figures, the same parts have the same referen~e numerals, and equivalent parts carry prime desiqnations. 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 rlgid pt~stic cover 10 of the screw top lQ type made from a plastic rnaterLal, for example, phenol, to the ir~terior of which there is securely faster~ed a highty elastic stopper 12. Both r~id cover 10 and elastic sto,oper 12 form a slngle inte~ral unit bonded together by a pressure ser sitive, strong--- bonding, ~ast-actirg, adhesive or glue 14. ~e adhesive ~4 may be ethyl cyanocrylate. One exarnple of such strong bonding gtue ~s commercially sold under the trademar5< "SUPER GLUE~" and is distributed by Loctite Corp. o~' Newington, Conrecticut.
The rigid cover t0 is .ubular in configuration with a smooth Rat eOI~ ard helically wound interior threads, as shown, adapted to engage the threads on the top portion oF the vial 16. Viat 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 surfac_ of the rigid cover is preferably knurted or provided with numerous equally spaced serrations as showr, to enable easy grasping of the cover. Itle exterior top sur~ace of the rigid cover need r,ot be ~lat 5~598 l~e highly el~stic stopper 12 is relatively sof~ and made of an etastomer such as raturat or synthetic t~pe rubber or a cornbir~tion of natural and synthetic type rubber, or a "rubber like" highly elastic soft flexible plastic such as polyvinyl chloride (PVC) or polyethylene - ethylene vin~yl acetate copolyrners. The rnaterial from which the stopper Is made must be highly elastic, able to stretch ur~er tow stress and sr,ap back to its ori~inal shape upon release of stress,. The PVC may be treated with an additiva to provide the desired elastic properties. The synthetic t~pe rubber may, for example,, be neoprene or siticon rubber.
The highly elastic stopper has a smooth ftat top area to which the glue t4 is applied for attachment to the interior of the rigid cover 10, as explained in more detail hereirafter. Stopper 12 is devoid of ary relatively hard or stiff plastic material and has such high elasticity that it always returns very rapidly to its origir~l size and shape shown in Figs. 1 to 5 after repeated flexing and stretching during usages 0lc the cover cap of the invention. The centr31 portion of the stopper 12 facing the op~n erd of the glass vial is provided with a sm~oth concave hollow area 18 to enable the liquid solution, such as blood, in the-vial to flow thereover during agitation of the contents of the v;al without collectir~ ary part of the solution on its surfac~. The smoothly rounded ends 20 of the concave hollow area 18 promote the mixing action or the blood and aid in minimizing or eliminatir~ en;tirely blood retaining, intersection areas.
The ti~y slass beads or ~all bearings hereinbefore mentioned, contained in the vial, roll over the rounded ends 20 and into the coricave ir~erior 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.

~1 59~
A protruding circular lip or shoulder 22 of the stopper 12 engages the interior o~ 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 12 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 l? provides space into which the lip can flex in the sealing position of Fig. 5. The surface of the stopper may 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 13 to allow any undesired excess of glue 14 applied during thebondingprocess o~ 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 rigj~d material for its cover, where it is needed, and a soft, highly elastic material for its stopper, as is - 13 ~

;lS9l~

required for the sealing operation; as distinguished from a closure cap made of identical materials for both cover and stopper.

- 13a -~5;1598 rn the rnanuFacturing operation of producir~ the closure cap of Figs. 1 to 5 inclusive, the hlghly elastic stoppers are sterilized in an autoclave beFore being r,~oved into a glove box. The interior oF the glove box is a sterile environment due to a iqow of sterile air therethrou~h. Hand maniputation in the sterile box is achieved by an operator with sterile gloves affixed to sealed openings in the box Into which the operator inserts her hands. The sterile vials are moved in trays down the sterile box and the blood solutions inser~ed into the vials. The operator then selects a stopper, places it over the ol~en neck of the viat and by a single downward motion oP a finger tamps the stopper into the vial to produce an air and liqutd-tight seai. At this point in the operation there is no need to hold the vial.
The contents of the vial are, at this point, complètely sealed fron~
outside contamiration. The sealed vials are then moved to a station outside the sterile box and a drop of pressure sensltive, strong-bonding, ~ast-acting glue or adhesive 14, such as eth!,~l cyanocrylate material, is ptaced on top oF the pure rubber stopper t2. The glue drop rnay be approximatety l/lOth l~f a ml (~ 1/100 ml). Excess glue will flow into groove ~3 oF the elas.ic stopper. The open end of the rigid plastlc cover is then immediately placed over the stopper and screwed onto the ~hreads on the vial to the fullest extent, thereby ca~sing the smooth interior oF the top portion of the rigld plastic cover to firmly engage the top of the rubber stooper. The pressure-sensitive, strong-bonding glue spreads and bonds the stopper and cover i~o a slngle irtegral closure cap unit such that unscrewing the rigld cover results {n the removal of the hlghly elastlc rubber stopper from the vlal. The cover c~p of Figs. 1 to 5 can r,ow be used repeatedly to achieve firm air and tiquid--tight sealir~ of the llquid contents of the vlal merely by turning the rlgid cover on the vial in the proper direction.

The closure cap of the embodiment of Fig.6 differs Prom that of Fig. 1 primarity in the structure of tha highly etastic stopper. Here a~}ain, as in Fig" 1, the stopper 24 Ls securely bonded by a drop of strong~ondir~, fast-actirg, pressure-sensiti~2 glue to the ireerior top portion of the rigid ptastic cover 10' so that the rigid cover tO ' and the highly e1astic stopper 24 form a single intesrat unit. Although not shown in Figs. 6 to 10, the elastic stopper 24 may be provided with a circular groove in the top thereot' in the manrer shown in Figs. 3, 4 and 5 to allow undesired excess gtue to ftow therein during the bonding process of screw-type ca~r and stopper.
The stopper 24 of Figs. 6 to tO is designed for use in a freeze--dry operation on ~he contenes of vial 16. 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 Ftexible equal-length segments 28. These segments 28 surround an interior hollow space 30 which extends from the top of the stopper to i tS bottom and is longer than the slots 26. Each segment 2~ is provided with two spaced ridges 32 and 32 ' of the same etastic materia~ as the rest of the stopper. The lower portions of the segments 28 are tapered irn,Yardty 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 12. 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 s9~

The operatin~ steps which result in the ~reeze~iry process, ~he sealing of the vial~ and the bondin~7 oF the highly elastic rubber st~pper and the rigid plastic cover as a single integral will now be gi~en, The vial with its tiquid contents appears before the operator in a cl~an but not r,ecessarily a sterile ervironrnent. ~he operator ir~erts the stopper 24 partially ir,to the open neck oF the vial t6 urrtil the stopper rests on its lowermost ridge 3~ ', 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~ry chamber in which the tem~erature and ~c~lum are controlled, Due to the partial seating of the rubber stopper 24 in the neck of tha vial 16 there is Fluid ftow ^omm~nication between the freeze-dry chamoer and the interior of the vial through the slots 25 ar~ the centrally positioned hollo~ space 30. The vacuum in the freeze-dry chamber reduces the frozen contents of the vial to powder or grar~les, Observation of the condition of the vial contents can be rnade throush windows in the free2e~ry chamber.
After the freeze-dry operation Is completed and while the stopper is partial2y in place a shelf or similar object within the freeze--dry chamber descends to futly and completely seat the highly e2astic stoppers on the necks of the vials in the manner indicated by the position of the s~opper ln Fig. 10, to thereby tightly sea2 the powdered contents within the vial from the outside atrnos--ph~re. The elastic ridges 32 are sclueezed asain5t the interior neck part oF the ~ial to aid in sealing the vial. ~e sealed vials ~ith the stoppers in place are then removed from the drylng chamber into a clean area. The operator now places a drop of pressure~ensitive"
stron~--bon~ling, ~'ast~Lcting glue on the top of each stopper at~er ~vhich the rigid plastic screw type cover is immediately ptaced over the ~L~5 9 ~3 siopper and tightened over the neck of the vial so as to bond the stopper to the Lnterior top portion of the rigid c over as indi::ated in Fig~ 10 Tl is tast step is sirnitar to that hereinbefore described to form the bond between the rigid cover and the stopper oF the embodiment of Fig. t. 1nhe ccver 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 irtegral unit thereof, the highty etastic seatir~ stooper In ctosure cap embodlments of the invertion construs*ed and satis~actority testedJ the stopper was made o~ natural rubber which when subjected to three hur~red percent (300%) of elongation indicated a stress reading of twelve hundred pounds per square inch(1200 psL).
Atthcugh such a reading is preferred, the range of acceptable material for the highly elastic stopper may be from 300 psi up to 2500 psi.
~his rar,ge is not as great as it may seem, since it is not strict~y linear and the higher rx~mbers represent materiat that is har~er to st~etch as well as reflecting the fact that the materiat has a greater tenacit~ in retainina its original shape when subjected to stress as wetl as reh~rning to its origir,at shape when stress is removed. In contrast, normat ptastics, such as the rigid cover of the closure cap of the invertion, has a modulus of elasticity approxir.~ating 200,000 psi for the same degree of elongation.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. The 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.

2. The 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. The 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 suction in said chamber.

4. The method according to claim 1 or 2 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. The method of assemblying a reusable closure cap while 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.

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 condi-tion 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, said stopper being formed of a rubber which stretches approximately 300%
under a stress of approximately 1,200 p.s.i.

7. 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, said stopper being characterized by its ability to stretch under a stress in the range of approximately 300 psi up to 2,500 psi and to rapidly return to its original shape upon release of said stress.

8. A closure cap according to claims 6 or 7 wherein said closed end of said stopper forms a flat top area and said bottom portion includes a co-axially 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.

9. A closure cap according to claims 6 or 7, 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.

10. For use in the medical and biochemical art field, a reusable and removable closure cap for sealing a vial which has a uniformly dimensioned cylindrical opening exteriorly threaded at one end, comprising as a single integral unit a rigid tubular cover of plastic material interiorly threaded for registering with the threads on said vial, said cover being closed at only one end, a plug-type stopper of highly elastic and relatively soft material having a flat top area and a coaxially positioned bottom tapered portion, that part of said stopper which is below said flat top area having an annular lip intermediate the ends thereof which has a lateral dimension larger than the diameter of said cylindrical opening, but smaller than the lateral dimension of said flat top area, said tapered portion being adapted to enter the open end of said vial and to provide with said lip a liquid and air-tight seal for the contents of said vial, and a pressure-sensitive material of strong-bonding adhesive qualities bonding the central top portion of said rigid tubular cover in its interior to the central flat top portion of said highly elastic stopper, said stopper being characterized by its ability at room temperature to stretch under low stress and to return rapidly to its original shape upon release of stress.

11. A vial sealed with a reusable closure cap, said vial having an exteriorly threaded cylindrical opening of uniform diameter, said closure cap comprising a highly elastic fluid-impermeable plug inserted into said cylindrical opening, said plug having a tapered portion at its lowest end of a lateral dimension smaller than the diameter of said cylindrical opening, and an intermediate annular portion of a lateral dimension greater in its unflexed condition than the diameter of said cylindrical opening, said plug having at its top a flat flange-like body made of the same highly elastic material as said plug and integral there-with and of a lateral dimension which extends across and beyond said opening and rests upon the rim of the vial opening when said plug is, except for its flange-like body, completely inserted into said opening, and a rigid screw-type internally threaded cover inseparably bonded in its interior to the top surface of said flange-like body by a strong-bonding adhesive, said cover having been securely bonded to said flange-like body by twisting the cover over the exterior threads of said vial after said plug has been inserted into and sealed said vial and after the application of said adhesive to the top surface of said flange-like body, until the interior of said cover engaged said body.

12. A sealed vial according to claim 11, wherein the annular intermediate portion of said plug is an uninterrupted annular lip or shoulder above said tapered portion.