US3741422A - Method and means for secondary closure - Google Patents

Abstract

Described herein are methods and means for providing containers with secondary closures resistant to the passage of moisture, bacteria and the like. Heat recoverable tubular members having one or more integral tear tabs and preferably provided with a hot melt adhesive or other sealant material on the inner surface thereof are radially inwardly heat recovered about the generally cylindrical neck portions of containers provided with a primary closure such as a cap. The tear tab is preferably provided with a stress-raising characteristic positioned to resist tearing during radial recovery of the secondary closure and to facilitate removal of the same when the container is to be opened. Simultaneously with or following heat recovery the container, including the container-primary closure interface about which the tubular member is recovered, is sterilized.

Description

United States Patent 1191 Wold et a1. 5] June 26, 1973 [54] METHOD AND MEANS FOR SECONDARY 3,405,833 10/1968 Salzinger et al. 215/38 A X CLOSURE FOREIGN PATENTS OR APPLICATIONS 1 Inventor-$1 Robe" weld; Anthfmy 88 405,953 2/1934 Great Britain 229/1510. 12 bot of emon Cahf- 758,943 10/1956 Great Britain 215/38 A [73] Assignee: Raychem Corporation, Menlo Park, 1,088,552 10/1967 Great Britain 215/38 A Calif.

Primary Examiner -Robert S. Ward, Jr. Flledi 9, 1971 Attorney-Charles G. Lyon et al. [21] Appl. No.: 163,781

[57] ABSTRACT [5 2] US. Cl. 215/38 A, 215/46 A, 156/69, Described herein are methods and means for providing 229/DIG. 12, 53/14 containers with secondary closures resistant to the pas- [51] Int. Cl..,,, B65d 41/00, B65d 43/02, 1365!) 7/00 sage of moisture, bacteria and the like. Heat recover- [58] Field of Search 215/38 A, 46 A; able tubular members having one or more integral tear 229/DIG. 12; 156/69, 86; 53/14, 30 tabs and preferably provided with a hot melt adhesive or other sealant material on the inner surface thereof [56] References Cited are radially inwardly heat recovered about the gener- UNITED STATES PATENTS ally cylindrical neck portions of containers provided 3,623,624 11 1971 Fujio 215/46 A x with a pnmary i such as a .P' The p 2 790 285 4/1957 Pike a al 215/38 A preferably provided with a stress-raising characteristic 2:019:84} 11/1935 Black et 156,69 positioned to resist tearing during radial recovery of the 1 04 123 10/1925 Ingram et 215/4 A secondary closure and to facilitate removal of the same 2,105,367 1/1938 p 229 51 Ts when the container is to be openedhsimultaneously 2,141,722 12/1938 Morgan 215/38 A with or following heat recovery the container, includ- 2,l41,744 12/1938 Evans 215/38 A 7 ing the container-primary closure interface about 21157-342 5/ 1939 Armlwsc 215/46 A which the tubular member is recovered, is sterilized. 2,331,794 10/1943 Mallory 53/14 X 3,095,103 Harrison 215/46 A X 11 Claims, 6 Drawing Figures METHOD AND MEANS FOR SECONDARY CLOSURE BACKGROUND OF THE INVENTION This invention relates to methods and means for providing secondary closures to containers, and more particularly relates to tamper-proof secondary closures resistant to the passage of moisture, bacteria and the like.

Containers for liquid or solid food, pharmaceuticals and the like are commonly provided with primary closures such as threaded caps secondarily protected against tampering. Exemplary of such containers are the bottles in which so-called physiological fluids such as distilled water, saline and dextrose solutions are commonly supplied to hospitals for intravenous feeding and other purposes. As background to the present invention, there will now be described a typical method by which such containers have heretofore been closed and sterilized. An open bottle containing, e.g., intravenous feeding solution is removed from the filling line to the bottling line where a cap formed of aluminum or other metal and provided with aluminum, silicone rubber and impregnated paper disk liners is dropped over the neck of the bottle. A capping machine then rolls thread forms on to the cap, forming a primary closure. Another aluminum cap is dropped over the primary closure and crimped thereunder to form a tamperproof Secondary closure, i.e., when twisted the secondlit ary closure rotates rather than is removed so that the primary closure is not presented for extraction. The metal secondary closure is provided with a tear ring or other device as the only means of removal so that it can be readily determined by observation whether occasion has arisen for tampering with the primary closure. The closed bottle is then placed in an autoclave held, e.g., at about 20-25 psig throughout a typical sterilization cycle. The bottle is washed for, e.g., four minutes with unsterile water, after which the steam lines are turned up to generate about 264F air temperature in the clave. Thistemperature is maintained until the temperature within the bottle as determined by a thermocouple-supplied dummy bottle is about 239F. Air temperature in the autoclave is then backed off to about 250F to equilibrate the bottle temperature at about 239F and the bottle held at that temperature for, e.g., about 20 minutes. Steam pressure is then decreased and unsterile water injected into the steam to gradually reduce the temperature within the autoclave, ensuring that the difference between air temperature within the clave and bottle temperature is not greater than about 50F in order to prevent the bottle from bursting. This temperature reduction is continued until the bottle temperature is about 60F, whereafter the bottle is removed from the clave, dried, labeled and boxed for shipment.

' Quality control is had by disassembling a representative number of bottles so closed and sterilized and attempting to culture bacteria in the bottle contents and on, e.g., the interior surface of the bottle neck and the cap liner disks.

Container closure processes like that set out above, while widely used in the past, have not proved entirely satisfactory in ensuring against the possibility of bacterial passage beyond the primary closure and ultimately into the contents of thecontainer. Recently, intravenous solution containers processed as set out above have been implicated in a statistically significant number of septicemia cases in American hospitals. Among the microbial species isolated from sampled lots of such bottles were yeasts, Erwinia Species, S. epidermidis, E. cloacae and Pseudomonas maltophillia. Clearly, then, a continuing need exists for methods and means of secondary closure which the better assure against contamination without sacrificing considerations of economy, ease of secondary closure removal, and tamper-proof characteristics.

BRIEF SUMMARY OF THE INVENTION container about which it has been heat recovered.

One object of the present invention is to afford means for economic secondary closure of containers for food, pharmaceuticals and the like.

Another object of the invention is to provide such articles with means which facilitate their removal when desired without enhancing their susceptibility to pre mature splitting during heat recovery.

Yet another object of the invention is to provide secondary closure method and means which the better ensure containers against bacterial and other contamination.

A further object of the invention is to provide a tamper-proof secondary closure.

Still another object of the invention is to provide an improved method for effecting a secondary closure.

These and other objects and advantages of the invention will become apparent from the detailed description which follows and from the accompanying drawing in which:

FIGS. 1 (a) 1 (e) inclusive pictorially depict representative embodiments of the secondary closure means of the invention; and

FIG. 2 pictorially depicts one such secondary closure means heat recovered about a container.

DETAILED DESCRIPTION OF THE INVENTION The tubular, heat-recoverable closure devices of the invention are preferably cut from heat recoverable polymeric tubing. Methods for making heat recoverable tubing are disclosed in US. Pat. Nos. 3,086,242; 3,243,211 and 3,297,819, the disclosures of which are incorporated herein by reference. Briefly, a polymer susceptible to the impartation of elastic memory is extruded to form tubing having a first diameter, followed by cross-linking of the polymer by chemical means,

tures dominate the locked in stresses resulting from deformation of the cross-linked material. Upon reheating, the locked in stresses become dominant and the material tends to recover to its original cross-linked geometry.

FIGS. 1(a) 1(e) illustrate secondary closure devices formed according to this invention by cutting the illustrated shapes from polymeric tubing which has been rendered heat recoverable as described above. In particular, in each of FIGS. 1(a) 1(a) is illustrated an open-ended tubular member having first and second circumferential edges 11 and 12, at least one arcuate portion 13 of circumferential edge 11 extending longitudinally therefrom to form an integral tear tab 14. The closure device may be provided with more than a single tear tab, of course, as appears from FIG. 2 wherein tubular member 15 is illustrated as heat-recovered about the generally cylindrical neck portion of a container 16 provided with a primary closure cap 17, member 15 having plural tear tabs 18 and 19.

In operation, the secondary closure devices of the invention are employed simply by positioning the same about the generally cylindrical neck portion of a container provided with a primary closure and heat recovering the same radially inwardly to engage the container neck, protecting container-primary closure interface 20 against the ingress of moisture and bacteria. The portion of the container about which the tubular member is heat recovered must be sufficiently cylindrical as to ensure that, for a given degree of dimensional recovery, the recoverable closure will not by reason of its own recovery work itself off the container. In this respect, it is important to so position the recoverable closure 15 as to ensure that primary closure 17 protrudes therefrom above circumferential edge 21. The expanded diameter of the closure device need only be sufficiently greater than the neck diameter as to permit facile placement of the closure on the container. During recovery, if primary closure 17 does not protrude beyond circumferential edge 21, it has been discovered that the recovery forces of the tubular closure member will work the same off the neck portion. Where the configuration of the container admits, as in FIG. 2, the heat recoverable secondary closure is preferably sized such that circumferential edge 22 indexes upon that portion of the container which widens from the neck thereof in such fashion as to locate circumferential edge 21 below the top of primary closure 17.

The tear tabs are integral extensions of arcuate portions of a circumferential edge of the recoverable tubular members, i.e., the tabs themselves do not exhibit a closed curve in cross-section. Accordingly, the hoop forces arising during radial recovery do not obtain within the tear tab itself to an extent sufficient to encourage working of the recovering closure off the con tainer. The tear tabs facilitate removal of the secondary closure when it is desired to free the contents of the container. Thus, for example, the tear tab 14 of the embodiment illustrated in FIG. 1(a) can be edge-snipped with scissors or the like to form a stress-raising slit. Thereafter, the arms of the tear tab may be separately grasped and tugged downwardly and apart as is suggested by the arrows in FIG. 2 in order to tear the secondary closure from the container about which it has been recovered. Preferably, however, such stressraising characteristics are imparted to the closure devices of the invention during their formation from heat recoverable tubing. Thus, for example, the same operation which severs the individual closure devices from the tubing and forms the tear tabs themselves can impart stres -raising characteristics such as perforation 23 in FIG. 1(b), the train of perforations 24 in FIG. 1(c), the slit 25 in FIG. 1(d) or the notch 26 in FIG. 1(a). Preferably, such stress-raising characteristics proceed generally longitudinally toward the intersect of tear tab 14 with circumferential edge 11, as is shown in FIGS. 1(a) 1(e) and most preferably, albeit not necessarily, proceed from the outermost edge of the respective tear tabs. Where a stress-raising characteristic is imparted to the closure means before recovery of the same about an object, it is most important that the stress-raising characteristic be positioned sufficiently above the intersect of the tear tab with the circumferential edge of v the recoverable tubularmember as to resist premature tearing of the tab by reason of the hoop forces obtaining in the circumferential portion of the closure device during and following its heat recovery about an object. Thus, for example, in each of FIGS. 1(b) 1(e), the respective stress-raising characteristic is positioned well above the arcuate portion 13 of circumferential edge 11 from which the tear tab longitudinally extends. The minimum distance which may be tolerated between the stress-raising characteristic and the said intersect will vary depending upon, inter alia, the nature of the characteristic itself, the percent recovery and wall thickness of the recoverable closure, etc. For present purposes, of course, the notch or other stress-raising characteristic need extend but slightly from the outermost edge of the tear tab in order to facilitate commencement of tearing, so that little reason exists for attempting to preform the stress-raising characteristic as near as possible to arcuate portion 13 of circumferential edge 11.

Where the closed container is to be sterilized, the heat recoverable secondary closures are applied and pre-recovered before sterilization is effected. Recovery commences when the article is heated to a transition temperature above which the article was first deformed by expansion. For example, the low density polyethylene preferred in the practice of this invention exhibits a transition point at about 216F and commences recovery at about that temperature. Of course, recovery is accelerated at greater temperatures and for that reason will commonly be conducted at temperatures above the transition point of the material, e.g., the low density polyethylene articles are recovered at about 230-240F. Generally, recovery will be had at temperatures ranging from the transition point above which the article was expanded up to about 355F by passing bottles about whose necks the recoverable closures have been disposed through a tunnel. Where the bottles contain fluids which boil at the recovery temperature it is preferred that the heat tunnel be configured to selectively heat only that portion of the container about which the recoverable article has been disposed. Preferably, the tubular closures are sized relative to the containers about which they are to be recovered so as to be recoverable to an unrestricted diameter somewhat less than the container neck diameter so that the recovered closure is placed in tension.

In the preferred embodiments of the invention, the tubular closure is provided on its interior surface with a sealant material such as a mastic like those disclosed in US. Pat. No. 3,297,819 or, most preferably in the case where a tamper-proof, bacteria-resistant closure is required, a hot melt adhesive, i.e., an adhesive which is non-tacky at room temperature and gets its adhesive properties by passing through the melt and cooling. The mastic materials flow under conditions of recovery to form a caulking-type seal between the recovered article and the container-primary closure interface, while the hot melt adhesives pass through themelt to adhesively secure and seal the closure to the container about which it is recovered.

Adhesive sealing is facilitated where the substrate portion of the container is at an elevated temperature itself. While the substrate portion is heated in some degree during the prerecovery operation, it presently appears most convenient to effect seal formation during subsequent prolonged exposure of the container to sterilization temperatures in the autoclaves. Conventionally in the case of intravenous solutions, sterilization is effected at or above temperatures on the order of the atmospheric boiling temperature of the liquid present in the container processed. Where an autoclave is employed to sterilize a variety of fluids of varying atmospheric boiling point the cycle is for convenience commonly set to achieve temperatures at or above the atmospheric boiling temperature of the highest boiling fluid treated. Autoclave temperatures ranging from 212F to, e.g., 280F will then commonly be encountered and the hot melt adhesives employed chosen to attain melt temperature during sterilization temperature cycling. Alternatively, albeit not preferably, substrate portions of the containers may be preheated and melt sealing achieved simultaneously with prerecovery of the closure devices thereabout, etc.

The hot melt adhesives preferred are those which are non-tacky at normal storage temperatures and bond well to plastic, glass or ceramic containers, as the case may be, exhibiting shear strength of at least about 50 inch-pounds, most preferably greater than about 100 inch-pounds of torque. Tendencies toward blockiness, referring to the inclination of adhesives in sheet form to self-adhere at storage temperature, may be alleviated by incorporation of minor amounts, e.g., 1-5 percent by weight, of microcrystalline wax, stearates, etc., as is well known. Substantial incorporation of low molecular weight materials known to support fungus growth is, of course, to be avoided. Among the hot melt adhesives suitable in the practice of the invention may be mentioned polyamide resin adhesives such as those available from General Mills under the tradename Versalon, polyester adhesives (see, e.g., DuPont Technical Bulletin No. 17 Polyester Adhesives) and the wide variety of polyvinyl, polybutene and polyacrylate adhesives with which the art is familiar. An .especially preferred formulation is a blend of Versalon 1,140 and 1,165 (ring and ball softening points of, respectively, 284 and 329F), e.g., 20:80::l,165:l,140 by weight, coated onto the closure interior in about 30 percent wt. solids solution in, e.g., methanol.

While, as above noted, it is preferred that the heat recoverable closure of the invention be formed of polyethylene, other materials susceptible to the impartation of elastic or plastic memory may be used as well, e.g., various copolymers of ethylene, propylene and butene; polybutene, polyvinyl halides, e.g., polyvinyl chloride; polyacrylates; polyamides, e.g., nylon 6 or nylon 66; polyesters such as polyethylene terephthalate; fluorocarbon polymers such as polytetrafluoroethylene; ionomers and polyurethanes. The polymer may contain various additives such as, for example, opacifying agents,

pigments and the like. in particular embodiments, ad-

hesive materials may be blended with the polymer prior to extrusion of the tubing from which the closure de- 5 vices are formed as an alternative to provision of an interior layer of adhesive. One class of polymer additives especially suited to the applications in which the present invention finds employment are antimicrobial agents such as fungicides (e.g., chlorinated phenol derivitives) and antibacterial agents (e.g., Hexachlorophene, 2, 2'-thiobis [4,6-dichlorophenol], etc.). Antimicrobial additives may be employed in amounts ranging from, for example, about 0.1 to 5 percent by weight based upon the polymer.

Having fully described our invention with reference to the preferred embodiments thereof, we wish it understood that the invention is not limited thereto but only to the lawful scope of the appended claims.

I claim 1. An open-ended tubular member heat-recoverable radially inwardly toward the longitudinal axis thereof, at least one arcuate portion of one circumferential end extending longitudinally therefrom to form an integral tear tab, said tab being provided with a stress-raising characteristic positioned sufficiently above the arcuate portion of said circumferential end as to resist tearing of the tab when the tubular member is radially recovered about an object.

2. An article according to claim 1 having a layer of sealant material on the interior surface of said member.

3. An article according to claim 2 wherein said sealant material is a hot melt adhesive.

4. In combination, a container having a generally cylindrical neck portion and primary closure, and an article according to claim 1 positioned about the neck portion and container-closure interface, said primary closure protruding beyond a circumferential end of said tubular member.

5. The combination of claim 4 wherein said tubular member is provided with a layer of sealant material on the interior surface thereof.

6. The combination of claim 5 wherein said sealant material is a hot melt adhesive.

7. The process of providing a secondary closure on a container having a generally cylindrical neck portion and primary closure which comprises (1) positioning an open-ended tubular member about said neck portion over the container-primary closure interface such that the primary closure protrudes beyond a circumferential end thereof, said tubular member being heat recoverable radially inwardly toward the longitudinal axis thereof, at least one arcuate portion of one circumferential end of the tubular article extending longitudinally therefrom to form a tear tab; and (2) heat recovering said tubular member about said containerprimary closure interface- 8. A process according to claim 7 wherein the interior surface of said tubular member is provided with a sealant layer of hot melt adhesive, and which additionally comprises the step of melting said adhesive to form a seal along said container-primary closure interface resistant to the passage of moisture and bacteria.

9. A process according to claim 8 wherein said container is sterilized following heat recovery of said member.

3 ,74 1 ,422 7 10. A process according to claim 9 wherein the meltoccurs at a temperature less than the melting point of ing point of said adhesive is attained during recovery of said adhesive, said melting point being attained during said member. subsequent sterilization.

11. A process according to claim 9 wherein recovery

Claims (11)

1. An open-ended tubular member heat-recoverable radially inwardly toward the longitudinal axis thereof, at least one arcuate portion of one circumferential end extending longitudinally therefrom to form an integral tear tab, said tab being provided with a stress-raising characteristic positioned sufficiently above the arcuate portion of said circumferential end as to resist tearing of the tab when the tubular member is radially recovered about an object.

2. An article according to claim 1 having a layer of sealant material on the interior surface of said member.

3. An article according to claim 2 wherein said sealant material is a hot melt adhesive.

4. In combination, a container having a generally cylindrical neck portion and primary closure, and an article according to claim 1 positioned about the neck portion and container-closure interface, said primary closure protruding beyond a circumferential end of said tubular member.

5. The combination of claim 4 wherein said tubular member is provided with a layer of sealant material on the interior surface thereof.

6. The combination of claim 5 wherein said sealant material is a hot melt adhesive.

7. The process of providing a secondary closure on a container having a generally cylindrical neck portion and primary closure which comprises (1) positioning an open-ended tubular member about said neck portion over the container-primary closure interface such that the primary closure protrudes beyond a circumferential end thereof, said tubular member being heat recoverable radially inwardly toward the longitudinal axis thereof, at least one arcuate portion of one circumferential end of the tubular article extending longitudinally therefrom to form a tear tab; and (2) heat recovering said tubular member about said container-primary closure interface.

8. A process according to claim 7 wherein the interior surface of said tubular member is provided with a sealant layer of hot melt adhesive, and which additionally comprises the step of melting said adhesive to form a seal along said container-primary closure interface resistant to the passage of moisture and bacteria.

9. A process according to claim 8 wherein said container is sterilized following heat recovery of said member.

10. A process according to claim 9 wherein the melting point of said adhesive is attained during recovery of said member.

11. A process according to claim 9 wherein recovery occurs at a temperature less than the melting point of said adhesive, said melting point being attained during subsequent sterilization.

Images