Double screw cap system for sterile medical liquid container and method of opening same

Abstract

A sterile medical liquid container system that includes an inner cap and an outer cap nested together and having interconnecting splines. The inner cap has internal right-handed threads and is screwed onto a threaded bottle neck to hermetically seal this neck. The outer cap has external left-handed threads and is fused at a frangible joint to the thermoplastic bottle. A jacking ring with internal left-handed threads screws onto the outer cap and a continuous clockwise motion of the jacking ring acts to (1) fracture the outer cap, and (2) unscrew the combined intersplined inner and outer caps from the container neck.

Description

BACKGROUND

There have been various types of closure systems for sterile medical liquid containers. Many of these closure systems included an inner cap and an outer cap that form double sterility protector seals. In most cases the outer cap was removed as a separate step prior to opening the inner cap. In some medical circumstances this procedure may be desired. Examples might include opening the outer closure prior to connecting an administration set to the inner closure.

However, there are certain circumstances where it is desired to simultaneously remove the inner and outer closures as quickly and easily as possible. An example would be where a container with a double closure system has a measured volume of liquid that is to be poured into another container. Here the entire liquid contents of the first container would be dispensed at once. Another example would be where a physician desires to dispense a measured quantity of liquid into a surgical wound or the like. Thus, a physician can completely empty a 1/2 liter bottle of liquid into the wound and have a much more accurate volume record than he could by pouring out 1/4 of the liquid contents from a 2 liter container.

With previous containers having double closure systems the nurse or physician often had to go through an intricate tedious series of steps to open the container. This problem was aggravated when numerous bottles had to be opened for a particular medical procedure.

SUMMARY OF THE INVENTION

This invention provides a simple easy to open double closure system on a thermoplastic bottle for sterile medical liquids. A single counterclockwise unscrewing motion of the cap performs a sequence of opening steps. The double cap structure of this invention includes an inner cap with internal righthanded threads, and an outer cap with external left-handed threads. The outer cap fits over the inner cap and has a bottom end of the outer cap skirt sealed to the thermoplastic bottle. To prevent relative rotation, the inner and outer caps have skirts that are longitudinally splined together. During opening of this closure a jacking ring with internal left-handed threads is screwed onto the outer cap. Counterclockwise motion of this jacking ring first breaks apart the outer cap and then wedges tightly onto this outer cap. Continued clockwise rotation of the jacking ring simultaneously removes the interlocked inner and outer caps. The jacking ring and both caps are lifted from the bottle neck as a unit. To a nurse or physician opening the container, it appears that he is simply unscrewing a cap and pouring the contents in a simple easy motion.

THE DRAWINGS

FIG. 1 is a front elevational view of the bottle and closure system as it is stored prior to opening;

FIG. 2 is an exploded perspective view of the bottle and three elements of the closure system;

FIG. 3 is an enlarged sectional view through a left side portion of the closure system, with both inner and outer cap seals intact;

FIG. 4 is an enlarged sectional view of the left side portion of the closure system of FIG. 1 showing it in the process of being opened; and

FIGS. 5 to 8 illustrate the various steps in opening the special double cap system of this invention.

DETAILED DESCRIPTION

With reference to FIG. 1, the container is shown as a thermoplastic blow-molded bottle 1 that has an upper end portion 2 to which is attached the closure system, indicated generally as 3. At a lower end of the bottle is a base 4 and a hinged hanging tab 5. This hanging tab is for suspending the bottle in a mouth downward position if desired.

The various elements of the bottle and closure system are shown in more detail in FIG. 2. Here the top portion 2 of the bottle has a dispensing neck 6 that terminates in an outer pouring lip 7. Neck 6 has external threads 8 that are "right-handed." The term right-handed means that the cap screws downwardly on these threads with a clockwise rotational motion. At a base of neck 6 is an external thermoplastic flange 9.

Fitting onto this neck 6 is an inner cap 10. Inner cap 10 is internally threaded with right-handed threads which mesh with external threads 8 of the neck 6. Inner cap 10 includes a top wall 11 and a downwardly extending annular skirt 12. Extending longitudinally along an exterior surface of this skirt 12 are a series of ribs 13 and 14. The importance of these ribs will be mentioned later in their relationship to an outer cap.

A thermoplastic outer cap 15 fits over the inner cap and includes a top wall 16 and an annular downwardly extending skirt 17. At a lower end of skirt 17 is a thin thermoplastic frangible brim 18 integral with the inner cap. When the outer cap is assembled over the inner cap the frangible brim 18 is heat fused at an annular hermetic seal to flange 9. Thus, there is a double hermetic seal made by the closure system. The inner cap 10 hermetically seals against pouring lip 7 and the frangible brim 18 is hermetically sealed at an annular heat fusion joint with the flange 9.

Two important features of the outer cap are shown in FIG. 2. The first structural feature includes a series of internal logitudinal ribs 19 and 20 on an internal surface of skirt 17. These ribs 19 and 20 interfit between ribs 13 and 14 of the inner cap 10. Thus the inner and outer caps can move longitudinally but cannot rotationally move relative to each other. This inter-relationship is called an "intersplining" of the inner and outer caps. This intersplining can also be created by forming the ribs as small longitudinal serrations on only the inner cap or outer cap, and then diametrically shrinking the outer cap onto the inner cap to impress these serrations on the other cap. Such shrinking can be done by forming the outer cap with more internal stress than the inner cap and then stress relieving the two caps with steam sterilization. Such stress relief is explained in detail in an application Ser. No. 338,684, by Elmer F. St. Amand and Thomas R. Thornbury entitled "Threaded Closure System For Medical Liquid Container and Method of Making Same" filed Mar. 7, 1973.

Combined with this intersplining is an important thread feature of the outer cap. The threads 21 on an outer surface of skirt 17 of the outer cap are "left-handed" and threads 8 on an inner surface of the inner cap are right-handed. Thus the inner and outer caps can be considered a double screw closure system.

The top element shown in FIG. 3 is a rigid jacking ring 22. This jacking ring has a knurled or grooved outer surface 23 for easy gripping. An internal surface has left-handed threads 24 that interfit and mesh with the threads 21 of the outer cap.

When the bottle neck, inner cap, outer cap and jacking ring are all assembled after the bottle has been filled with its liquid contents and sterilized, it appears as in FIG. 3. Here the top wall 11 of cap 10 forms a first annular hermetic seal at 25 with the pouring lip 7 of the bottle neck. The outer cap forms the second annular hermetic seal at 26 at its annular fusion joint with the flange 9. The inter connecting rib 19 fits against a rib of the inner cap 10 to stop relative rotation of the inner and outer caps.

As previously mentioned, the container with closure system is shipped to the hospital as shown in FIG. 3. When it is desired to open the container the nurse or physician merely rotates the jacking ring counterclockwise. As the jacking ring 22 is rotated counterclockwise the left-handed threads 21 cause it to move downwardly a slight distance. This downward motion is not readily felt by the nurse or physician opening the bottle. To them it is a simple standard motion that they are quite accustomed to in unscrewing caps from bottles.

The sequence of steps happening internally of the double closure system as it is rotated counterclockwise is very important. As the jacking ring rotates counterclockwise it moves downwardly to exert a pressure on the frangible brim 18 that is fused to flange 9. This causes skirt 17 of the outer cap to be pulled upwardly until frangible brim 18 is ruptured. As the jacking ring is screwed down tighter and tighter against brim 18 it is simultaneously wedging more tightly against the outer cap. This wedging takes place between a non-threaded flange portion at a top of the jacking ring. This can be seen in FIGS. 3 and 4. In FIG. 4 the jacking ring and outer cap are wedged at a contact point between numeral 22 and numeral 16. There is also a wedging action between the jacking ring and outer cap caused by the fractured portion of the frangible brim wedging against a lower portion of the jacking ring as shown in FIG. 4. The purpose of these two wedging actions at the top and bottom portion of the jacking ring is to prevent further counterclockwise rotation of the jacking ring relative to the outer cap after the brim has been fractured. A wedging action can also be created by terminating the threads of the jacking ring short of its top end, so the jacking ring and outer cap wedge when the upper end of these threads are reached by the outer cap threads.

When the brim 18 has been fractured continued counterclockwise rotation of the jacking ring simultaneously rotates the outer cap and the inner cap. Thus the jacking ring outer and inner caps are removed as a unit. The inner cap will preferably fit tightly enough in the outer cap so that the weight of the inner cap will not cause it to fall out of the outer cap. Therefore, the three part unit can be unscrewed and feels as a single cap to the nurse or physician.

This double screw closure system, with the left and right-handed threads, and the intersplining between the two caps, needs only a single counterclockwise motion to open the inner and outer hermetic seals. FIGS. 5 to 8 illustrate the steps in opening this double screw closure system. FIG. 5 shows the jacking nut as it is received at the hospital and is stored. Preferably the jacking nut has a slight space between jacking ring 22 and flange 9. This is so the jacking ring will not place undue stress on the frangible brim of the outer cap that is sealed to flange 9. To open the double closure system of this invention the jacking ring is rotated counterclockwise as in FIG. 5 to move it downwardly into contact with the flange 9. The jacking ring 22 is further rotated as in FIG. 6 to fracture the outer cap at its frangible brim 18. After fracture, the inner and outer caps and the jacking ring are simultaneously removed in a continuation of the counterclockwise rotation of the cap system. Once removed, the liquid contents from the container can be simply poured out as in FIG. 8.

The closure system and bottle of this invention work exceptionally well if the bottle is made of a polyallomer such as a propylene-ethylene copolymer thermoplastic material and the outer cap is likewise of the same propylene-ethylene copolymer thermoplastic material fused to this bottle. Eastman Chemical Company markets such a polyallomer under the name of TENITE. The inner cap and the outer jacking ring can be made of suitable rigid thermoplastic material.

In the foregoing specification and drawings a specific example has been used to illustrate the invention. However, it is understood by those skilled in the art that certain modifications can be made to this embodiment without departing from the spirit and scope of the invention.

Claims

We claim:

1. A container with inner and outer closures for storing and dispensing sterile liquids, which includes a blow molded thermoplastic container with a dispensing outlet, said container and outer closure forming a unit that has a transverse abutment means surrounding the outlet, wherein the improvement comprises:

a threaded dispensing neck on the container; a threaded inner closure connected to the dispensing neck and forming a hermetic seal therewith to create a sealed unit; a separately formed injection molded outer cap with a longitudinal axis; said outer cap having both a thin frangible section and externally exposed threads, and said outer cap is sealed to the container proximate said abutment means with an annular bacteria-tight bond with the threads of the outer cap being in a predetermined alignment with the abutment means whereby said threads can receive a threaded opening member and guide it toward the abutment means for exerting a pressure against the abutment means to axially pry the outer cap apart at its frangible section; and rotational stop means on the outer cap and inner closure to prevent rotation of the outer cap relative to the inner closure.

2. The combination as set forth in claim 1, wherein the combination also includes an internally threaded jacking ring threadingly disposed on the outer closure threads.

3. The combination as set forth in claim 1, wherein the threads of the inner cap are right-handed and the threads on the outer cap are left-handed.

4. The combination as set forth in claim 1, wherein there is a jacking ring threadingly disposed on the outer cap threads for fracturing the outer cap; and the jacking ring and outer cap have wedging structure that stops relative rotation between the jacking ring and outer cap after fracture.

5. The combination as set forth in claim 1, wherein the rotational stop means between the inner closure and outer cap include a series of longitudinally slideable interconnecting ribs internally of the outer cap and externally of the inner closure.

6. The combination as set forth in claim 5, wherein the ribs are formed as longitudinal serrations on one of the outer cap and inner closure, and the outer cap is diametrically shrunk to impress the serrations of one of the outer cap and inner closure into the other of the outer cap and inner closure to create a longitudinally slideable rotational stop means between the outer cap and inner closure.

7. The combination as set forth in claim 6, wherein the diametral shrinking is performed by steam sterilizing the container and closure system.

8. The combination as set forth in claim 1, wherein the container has a flange as the abutment means and the outer cap has an external frangible brim heat fused at an annular hermetic seal to said flange.

9. The combination as set forth in claim 8, wherein the combination includes a threaded jacking ring that pries apart the outer cap and abuts at least a portion of the frangible brim of the outer cap to limit the rotational movement of the jacking ring relative to the outer cap after the frangible brim has been fractured.