Closure cap for an infusion flask

Abstract

A closure cap which is applied to the closed neck of an infusion flask to provide a sterile seal therefor comprises a tear-off portion which when removed exposes a sealing disc which can be perforated by the canule of a syringe. The sealing disc is cast or moulded within the cap in engagement with the end wall of the cap and the tear-off portion therein, the said portion having at least one projection on its inner face which locally reduces the thickness of the sealing disc by providing an indentation in the disc which identifies a prepared point of perforation. The closure cap can be fixedly connected to the neck of the flask, and locating means may be provided on the cap and the flask to determine a preset rotational position of alignment of the cap and flask.

Description

FIELD OF THE INVENTION

This invention relates generally to infusion flasks, and more particularly to closure caps for infusion flasks. It is to be understood that the term "infusion flasks" as used throughout this specification and the appended claims is intended to embrace any medical or pharmaceutical container containing an injectant that can be drawn out through the canule of a syringe, and that the closure caps of the invention are applicable to the closure of all such containers.

DESCRIPTION OF THE PRIOR ART

It is already known in the art to close an infusion flask by means of a closure cap which is applied to the closed neck of the flask and provides a sterile seal. The cap contains a sealing disc and has an integral cap portion which can be torn open or torn off to uncover the sealing disc when the infusion flask is to be used. After the removal of this tear-off portion of the cap the underlying surface of the sealing disc is exposed. The sealing disc is capable of being perforated after it has been uncovered and exposed in this fashion. For the purpose of facilitating perforation of the sealing disc as by the canule of a syringe, the disc is provided with a prepared point in the form of an indentation where perforation is to take place.

In infusion flasks which have been moulded from plastics material and closed on a machine a parting seam is formed across the closure surface, along the neck and along the flask. The material is naturally thicker where the parting seam is located. Such a seam is not visible after the removal of the tear-off cap portion, and the presence of this seam may be a major nuisance when the disc is being perforated and it may be responsible for bending the capsule of a syringe. It has therefore been further proposed to locate the prepared point of perforation so that the parting seam cannot be an obstruction to perforation, by providing the closure cap, the sealing disc and the neck of the flask with locating means which when aligned in a prescribed manner, ensure that the point of perforation is suitably positioned. However, the provision of such locating means complicates production and raises the cost.

OBJECT OF THE INVENTION

It is therefore a primary object of the present invention to provide a closure cap for infusion flasks, which is suitably contrived to simplify production on a mass production basis and to improve the serviceability of the closure above that of conventional forms of construction.

SUMMARY OF THE INVENTION

A closure cap for application to the closed neck of an infusion flask to provide a sterile seal therefor, the cap comprising a skirt adapted to embrace the neck of the flask and an end closure wall, a sealing disc cast or moulded in engagement with the inner face of the end closure wall, a tear-off cover portion integrally formed in the end closure wall whereby the sealing disc is exposed through the end closure wall when said cover portion is removed, and at least one projection on the inner face of said cover portion which locally reduces the thickness of the sealing disc for perforation.

The above form of construction of the closure cap provides a number of important advantages. The production of the closure cap can be considerably simplified by injection moulding or casting the sealing disc into the cap. The indentation in the sealing disc which identifies the prepared point of perforation and is produced by the at least one projection in the tear-off cover portion which locally reduces the thickness of the sealing disc, is in a predetermined position in relation to the closure cap. The material forming the sealing disc can be sterilised in production, so that a sterile surface for perforation is exposed when the cover portion is removed. The indentation identifying the point of perforation is automatically produced when the sealing disc is moulded or cast.

Conveniently the closure cap may be made in a plastics material, or in a metal such as aluminium. However, generally speaking the use of a plastics material appears to offer advantages in convenience and cheapness of production costs.

Suitable materials for forming the sealing disc include a large number of rubber-elastic compositions which can be formed by a moulding or casting process. A particularly suitable material is an unvulcanised calendered natural rubber, a disc of which can be moulded by vulcanisation in situ in the cap.

The use of injection moulding and/or vulcanisation techniques in the moulding process offer advantages in that moulding temperature is usually sufficiently high to sterilise the surfaces of the resultant sealing disc, so that no separate sterilisation procedures are required. For example, a temperature of 130.degree.C would appear to be possible and would give rise to a sealing disc having sterile surfaces after the moulding process.

Particularly suitable plastics materials for the closure cap include polyethylene, polyvinyl chloride and polypropylene, which can also be satisfactorily heat sealed. It is desirable that the materials chosen for the closure cap and the sealing disc should be such that the tear-off cover portion will detach from the surface of the sealing disc without sticking thereto.

If the infusion flask is formed with a peripheral collar on the neck of the flask, it may be useful to attach the closure cap to the collar. Suitable the closure cap may be bonded to the collar as by the employment of suitable adhesives or by welding, or the cap may be attached to the collar by use of an additional metal or plastics coated flanging ring.

Moreover, it may be advantageous for the closure cap to be a snap-fit onto the neck of the collar. This may be achieved, for example, by forming the skirt of the closure cap in a manner such that it is adapted to snap onto the neck of the flask. The neck of the flask may be formed with an undercut shoulder and an internal peripheral rib on the skirt of the cap may be engaged beneath the shoulder. This arrangement could, of course, be reversed by providing a rib on the neck of the flask and a shoulder on the skirt of the cap. The provision of a snap-fit connection of such a kind provides an additional means of safely holding the closure cap in position.

A convenient method of producing a closure cap of the abovedescribed kind comprises filling a mouldable sealing disc material into the cap and moulding the sealing disc offset material in situ in the cap at a temperature high enough to sterilise the surfaces of the sealing disc.

Since the formation of the indentation establishing the point of perforation in the sealing disc occurs at the time the sealing disc is produced by moulding the disc material in the cap, and the position of this indentation in relation to the cap is thus assured, such a closure cap can be very conveniently located in relation to the parting seam of a plastics flask by providing means on the flask and on the cap for locating the flask and cap in a predetermined relative rotational position, thus permitting the closure cap to be applied to the flask in a production machine and the prepared point of perforation to be automatically located away from the parting seam and/or any other undesirable surface regions of the infusion flask.

Such locating means may with advantage comprise flat surfaces on at least one side of the cap and the flask respectively adapted when aligned or registered to determine the rotational position of the cap relative to the flask.

The above and further features and advantages of the invention will now be more fully described with reference to the accompanying drawings, which illustrate a preferred embodiment of the invention somewhat schematically.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a section of a closure cap according to the invention applied to the neck of an infusion flask, and

FIG. 2 is a top plan view of the cap in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 of the accompanying drawings, there is shown an infusion flask made of a synthetic plastics material. The infusion flask has a neck 2 on which is formed a peripheral collar 12. The parting seam of the flask, whereat the material is thickest, is indicated by the line 13.

The neck 2 of the infusion flask is embraced by the skirt 3a of a closure cap 3 which also comprises an integral end closure wall 4. having a tear-off cover portion 4a integrally formed therein. Tear-off cover portion 4a is defined by an annular groove 16 extending into closure wall 4 from the inner face 4b thereof. With cover portion 4a in place, the cap 3 is sealed. A ring-shaped finger grip 5 is provided on cap 3. By gripping grip 5 and pulling the cover portion 4a is torn off around groove 16 which constitutes a predetermined line of weakening in the end closure wall 4. In order to facilitate tearing off the cover portion 4a the end wall 4 may further be provided with a point of preferential initial fracture, such as a triangular nib adjoining groove 16 at a selected point.

The mouth 7 of the infusion flask 1 is sealed by a sealing disc 6 which has been formed by moulding or casting a compounded rubber material into the cap 3 in engagement with the inner face 4b of the end closure wall 4. At least one protuberance or projection 8 on the underside of the cover portion 4a projects into the sealing disc 6. Projection 8 is suitably in the form of a boss integral with the cover portion 4a. The projection 8 locally reduces the thickness of the sealing disc and provides a prepared location for effecting perforation of the sealing disc 6 by the canule of a syringe (not shown) once the cover portion 4a has been torn off.

Cap 3 is an injection moulded plastics material which does not stick to the surface of the material constituting the sealing disc 6.

The inner surface of the skirt 3a of the closure cap 3 is formed with projecting peripheral rib or flange 9 which by snap-action engages beneath an undercut shoulder 10 encircling the neck 2 of the flask. The rim of the closure cap 3 is further formed with a flange 11 which can be bonded to the peripheral collar 12 on the neck of the flask by hot sealing, with an adhesive or by like means or with the aid of a flanging ring (not shown) to firmly attach the closure cap 3 to the flask 1.

Locating means are preferably provided on the closure cap 3 and on the neck 2 of the flask for locating these parts in a predetermined rotational position when the cap is being fitted onto the flask, for example to ensure that the prepared point of perforation is not near the parting seam 13 of the flask or near some other undesirable part of the surface of the flask. The locating means suitably comprise flat surfaces on at least one side of the closure cap 3 and the flask 1. In the embodiment shown, the locating means comprise diametrically opposed pairs of flats 14 on the closure cap 3 and flats 15 on the collar 12 of the neck 2 of the flask 1 which permit corresponding parts of the circumference of the cap 3 and of the neck 2 to be mechanically aligned in a bottle closing machine.

When casting or moulding the material comprising the sealing disc 6 into the cap 3, the moulding process carried out in situ in the cap is preferably carried out at a temperature which is high enough to sterilise the surfaces of the sealing disc. Thus, an unvulcanised calendered natural rubber disc may be vulcanised in situ in the cap and sterilised automatically in the course of the vulcanisation. When an injection moulding process is used to form disc 6, the temperature of the material will normally be high enough to ensure sterilisation of the material in producing the disc.

A sterile surface of the sealing disc is thus exposed when the cover portion 4a is torn off.

It is to be understood that the embodiment described herein is merely illustrative of the principles of the invention. Various modifications thereto may be effected by a person skilled in the art without departing from the spirit and scope of the invention.

Claims

I claim:

1. A closure cap for application to the closed neck of an infusion flask to provide a sterile seal therefor, the cap comprising a skirt adapted to embrace the neck of the flask and an end closure wall, a sealing disc cast or moulded in engagement with the inner face of the end closure wall, a tear-off cover portion integrally formed in the end closure wall whereby the sealing disc is exposed through the end closure wall when said cover portion is removed, and at least one projection on the inner face of said cover portion which locally reduces the thickness of the sealing disc for perforation.

2. A closure cap according to claim 1, wherein the at least one projection comprises a boss integral with said cover portion.

3. A closure cap according to claim 1, wherein the sealing disc comprises an injection moulded elastomer.

4. A closure cap according to claim 1, wherein the sealing disc comprises a natural rubber and is moulded by vulcanising the material in situ in the cap.

5. A closure cap according to claim 1 which comprises a synthetic plastics material.

6. A closure cap according to claim 1, wherein said tear-off cover portion is defined by an annular groove which constitutes a predetermined line of weakening in said end closure wall and said wall further comprises a point of preferential initial fracture adjoining said groove.

7. An infusion flask comprising the closure cap as claimed in claim 1 and a peripheral collar on the neck of the flask to which said closure cap is attached.

8. An infusion flask according to claim 7, wherein the closure cap is bonded to the collar.

9. An infusion flask comprising the closure cap as claimed in claim 1 and the skirt of the cap is adapted to snap onto the neck of said flask.

10. An infusion flask according to claim 9, wherein one of said neck and skirt has an undercut shoulder and the other of said neck and said skirt has a peripheral rib engaged beneath said shoulder.

11. An infusion flask comprising the closure cap as claimed in claim 1 and means on said flask and said cap for locating said cap and flask in predetermined relative rotational position.

12. An infusion flask according to claim 11, wherein said locating means comprise flat surfaces on at least one side of said cap and said flask respectively adapted when aligned to determine the rotational position of said cap relative to said flask.

13. A method of manufacturing a closure cap as claimed in claim 1 which comprises filling a mouldable sealing disc material into the cap and moulding the sealing disc of said material in situ in the cap at a temperature high enough to sterilise the surfaces of the sealing disc.

14. A method according to claim 13, wherein the moulding process employed is an injection moulding process.