Technical Field

Injection sites made of natural rubber latex and similar puncture-resealable rubber discs and membranes are well known and in common use to cover ampules of vaccines and other medications, as well as for providing access to parenteral solution containers and sets for the delivery of solution to a patient. Injection sites are also used in other technologies such as gas chromatography. For example, Ward U.S. Patent No. 4,279,352 shows a type of molded injection site that can be placed upon the end of tubing communicating with a container for parenteral solution or the like. A latex cap is used on the VIAFLEX® solution containers sold by Travenol Laboratories, Inc. as an injection site.

In Penn et al. U.S. Patent No. 2,702,773 and Maruyama U.S. Patent No. 4,254,884, flat pieces of rubber, such as a rubber disc, may be bonded to a segment of other material through adhesion provided by coatings on all or part of the major faces of the flat component. The coatings may be made of ther oplastic aterial .

Mc inney U.S. Patent No. 3,551,273 discloses a septum for use in a gas chromatograph comprising a layered rubber disc. In accordance with this invention, improved designs of injection site utilizing a puncture-resealable rubber disc are provided, along with methods of manufacturing such injection sites, which can be manufactured with greater ease and reduced cost to provide high-reliability, inexpensive injection sites that do not fall off, as do some known injection sites of the medical field. The systems are particularly susceptible to automation, with a reduced reject rate over other designs for highly desirable mass production purposes.

Description of Invention

By this invention an injection site can be provided which comprises a disc of puncture-resealable rubber having opposed major faces and defining a periphery between the faces. The periphery carries a coating of plastic material , typically thermoplastic, with the major faces being essentially free of said coating. A surface, for example the inside of a tube or a fl at surface, may be made of a material sealingly compatible with the coating carried on the periphery, and the coating is sealed to that surface.

It is to be understood that the term "disc" does not necessarily call for a structure of round periphery. Other fl at, wafer-like structures may be used as equivalents thereto, for example oval or square, flat, disc-l ike structures may be used as a substitute for the typically preferred disc of round periphery.

Puncture-resealable rubber material s are well known to those skilled in the art, so it is unnecessary to recite a complete list of them. Typical ly, natural rubber latex or equivalent polyisoprene rubbers of artificial manufacture are used, but any other appropriate hydrocarbon rubber or other material which exhibits sufficient resealability to withstand a needle puncture under the circumstances of use may be used to make the puncture-resealable rubber discs. Included among the group of unsaturated polymers would be natural or synthetic poly soprene, polybutadiene, styrene-butadiene rubber (S8R) styrene-ethylene-butadiene-styrene (SEBS) , nitrile-butadiene rubber (NBR) and polychloroprene. Al so included are the cl assical saturated or semi -saturated el astomers such as polyisobutylene-polyisoprene copolymer (butyl rubber) , ethyl ene-propylene based polymers (both EPR and EPUM) , and si l i cone rubber. Cross-blends of any of these material s including combinations of them may al so be used.

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Similarly, the coating of plastic material carried on the periphery of the disc may be any desired thermoplastic material which is sealingly compatible with the disc and the surface to which it is to adhere. It is typically contemplated that the adhesion step of the coating to the surface will be performed by a heat sealing process, preferably ^' a radio frequency sealing process or an ultrasonic sealing process, or impulse sealing techniques, which are well known and in wide commercial use. Also included would be a technique of a limited adhesion of the disc injection site that would allow for the desirable removal of such an injection site if deemed necessary for a particular appl cation. If desired, solvent sealing with cyclohexanone or the like or other adhesive techniques may be used for the adhesion purposes as well. Also, the plastic material may be an uncured adhesive which is then cured to bond the disc to the seal ngly compatible surface.

Polyvinyl chloride plastic formulations are often preferred as both the coating of thermoplastic material and the surface to which it adheres, since it shows good advantage in RF sealing processes. However, if one desires to seal the injection site of this invention to a polyolefin container, for example polyethylene or polypropylene, the coating of thermoplastic material on the periphery of the disc may be made of a corresponding sealingly-compatible material, with impulse welding being used.

One candidate for the coating of thermoplastic material on the periphery of the disc for bonding to polyolefin containers is poly(ethylene-propylene-nonconjugated diene), for example SANTOPRENE sold by Monsanto Chemical- Company. An advantage of this material is that, while thermoplastic, it has a softening temperature high enough to withstand autoclaving without serious softening, rendering it a candidate for use in polyolefin containers for medical solutions and the l ke.

A multi -layered polymeric structured coating of periphery of the disc could be tailored to specifical ly address non-co patable interfaces. For example, a co-extruded coating over the rubber rod (i .e. polyisoprene that is coated with a polyester el astomeric al loy) coul d be over-coated simul taneously or later with a non-polar polymer such as polyethylene. ^" Thi s method would allow for the surface to be more compatible to the surface that it would ul timately be attached to, permi ting faster and better coating. Simil arly, many other thermoplastic material s can be used to adhere the injection site to a large variety of plastic and other surfaces. For example, besides pol vinyl chloride coatings, polyolefins such as polyethylene or polypropylene may be used. Thermoplastic polyurethanes are al so usable, often having good adhesion properties; plus mixtures of thermoplastic formulations. For example, thermoplastic formulations having ingredients as described in U.S. Patent No. 4,225,688 may be used.

Primers and adhesives may be used if desired to render the puncture-resealable rubber disc more firmly bonded to the peripheral coating of thermoplastic material . The nature of the primer or adhesive wil l depend upon the type of puncture-resealable rubber and the type of thermoplastic material used. When the disc is made of a polyisoprene rubber such as natural latex or a similar hydrocarbon rubber, the rubber may be chlorinated or brominated at its surface to render it more adhesive to polyvinyl chloride (PVC) thermopl astic, a PVC alloy, or a polyethylene (PE) or PE alloy, or a mixture of PVC and PE or any combination of PVC/PE and PVC alloy and/or PE all oy, for example. One may al so al low the rubber, while stil l in its thermoplastic state, to obtain a temporary bond to the overcoated material s. This can be accompl ished by a true coextrusion process that simultaneously extrudes a non-cured self-seal ing type of rubber while al so coating it with a

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thermoplastic. A permanent bond is then obtained during the cross-linking stage of the rubber. Such cross-linking of the rubber can be achieved by a well known method of heat curing (for example by autoclaving) or gamma-radiation. Electron beam 5 curing is also possible.

The injection sites of this invention may be manufactured by coating a solid rod of puncture-resealable rubber with a thermoplastic coating material. The coated rod is then transversely sl ced into a plurality of discs which, as a

1U consequence of this, carry the thermoplastic coating material only at their peripheries and not on the opposed major faces, which are. created by the slicing action. Thereafter the thermoplastic coatings of the discs are sealed to seal ngly compatible surfaces, to affix the discs into predetermined 5 positions relative to said surfaces.

Specifically, the sealingly compatible surfaces may be surfaces defining the bores of sealingly compatible tubes. Alternat vely, the coated disc may be placed on a flat surface of sealingly compatible material with one of the major faces 0 typically in abutment therewith, and an annular edge of the coating is sealingly adhered thereto, preferably by a heat seal technique such as radio frequency sealing, ultrasonic sealing, or impulse sealing so that the resulting seal between the compatible surface and the thermoplastic coating is an annular 5 seal .

The coated discs of this invention are usable as injection sites for medical apparatus as described or for similar uses in other technologies. They may also be used as membranes and partitions which may be easily held in place by the U thermoplastic, peripheral ring for penetration by a spike without intended resealing, or as a semipermeable membrane or as any other desired membrane or barrier. They may be also used for various mechanical purposes, being conveniently attachable by the thermoplastic, peripheral ring of this invention.

Similarly, the solid rod of puncture-resealable rubber with its thermoplastic coating material may be readily applied by heat sealing or other technique to various surfaces and retained for various mechanical purposes as above, such as a bumper, a reinforcement, a shock absorber, an insulator, or the like.

Description of the Drawings

In the drawings, Figure 1- is a fragmentary, partially exploded elevational view of a flexible, collapsible solution container carrying two different embodiments of the injection site of this invention.

Figure 2 ^* is an enlarged, fragmentary elevational view, with portions broken away, showing one of the injection sites of Figure 1. Figure 3 is an exploded elevational view showing a Y-tube injection site, usable as a component of a blood or solution administration set, or the like.

Figure 4 is a generally schematic view of part of an automated manufacturing process for mak ng injection sites in accordance with this invention.

Figure 5 is a longitudinal sectional view, substantially enlarged, of the other injection site of Figure 1.

Figure 6 is a longitudinal sectional view of an alternative embodiment for the other injection site of Figure 1.

Description of Specific Embodiments

Referring to Figure 1, a solution container, for example a container of solution for parenteral administration or for peritoneal dialysis, comprises walls 10, 12 which may be made of a thermoplastic such as polyolefin or polyvinyl chloride plastic, sealed together at the periphery 14 with a radio frequency heat seal. Except as otherwise indicated, the container may be, for example, of the design of VIAFLEX® solution containers sold by Travenol Laboratories, Inc.

As shown, the container may carry a pair of ports 16, 18 which are sealed in heat seal 14 for firm sealing retention therein to provide communication with the interior of the container. Within each of ports 16, 18 is a smaller molded membrane port 20, which can be seen to carry membrane 22 across its bore.

In accordance with this invention, injection site member 24 may be made of a disc 26 (Fig. 2) of puncture-resealable rubber, particularly polyisoprene rubber, and coated on its periphery with an annular coating 28 of polyvinyl chloride plastic, or other thermoplastic material.

As shown in Figure 2, injection site member 24 may be placed within membrane tube 20 to abut against membrane 22 for positioning, or alternatively membrane tube 20 may be omitted for cost saving, and injection site member 24 adhered directly to the bore of port 18. Both ports 16 and 18 and membrane tubes 20 may be made of polyvinyl chloride plastic or an alloy of polyesters, so in manufacture the entire array of port 18, membrane tube 20 (when used), and injection site member 24 may be heat sealed together with a conventional radio frequency sealing machine to form a firm, tight hermetic seal between coating 28 and the inner bore of membrane tube 20, and the outer periphery of tube 20 and the inner bore of tube 18. The resulting arrangement provides a need!e-resealable injection site which is free of some of the prior art problem of popping off at inconvenient moments, as has been the case with some commercial injection sites used with containers of the type shown. As stated above, the adhesion between a PVC peripheral coating 28 and rubber disc 2b can be promoted by means of a primer, for example, by chlorination or another halogenating process of the periphery of rubber disc 26.

As shown in Figure 2, rubber disc 2b defines opposed major faces 30, 32, one of which may abut membrane 22 and the other of which is exposed to the exterior.

Referring to Figure 3, branched tubing 34 may be made out of polyvinyl chloride plastic or any other desired thermoplastic material and comprises a pair of branched, interconnecting tubes 36, 38. Tube 38 defines an enlarged socket member 40 which, in turn, defines an aperture 42 proportioned to receive injection site member 24a, which may be of similar or identical design to injection site member 24, being a disc of puncture-resealable rubber having opposed major faces and defining a periphery between the faces, with the periphery only carrying the coating 28a of thermoplastic material, specifically polyvinyl chloride plastic, to be sealingly compatible with the plastic material defining socket 42.

After radio frequency sealing, also impulse sealing, or solvent bonding of injection site member 24a into socket 42 a firmly affixed injection site is thus provided, which may then be included as a component of a tubular set in generally conventional manner for parenteral solution sets, blood administration sets, sets for peritoneal dialysis or hemodialysis, or any other desired use. A second injection site 44 is shown carried on the collapsible solution container of Figure 1.

Typically, a container will carry only one and not both of injection sites 24 or 44, the two sites being shown on the container of Fig. 1 for economy of illustration. Figure 5 shows injection site 44 in greater detail. As in the previous embodiments, injection site 44 may include a disc 46 of puncture-resealable rubber such as natural rubber latex, coated on its periphery with a coating of thermoplastic material 48 such as polyvinyl chloride. Injection site member 44 may in fact be of identical design to injection site member 24, although it may be desirable for coating 48 to be somewhat thicker than coating 2b.

As shown, injection site 44 rests upon the surface of wall 10, which may be made of polyvinyl chloride plastic or another

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thermoplastic which is sealingly compatible with the coating 48 of thermoplastic material. In this instance, major face 50 of rubber disc 4b abuts wall 10, being retained in position by an annular heat seal 52 which provides a hermetic seal to the area within the annular seal. Thus a hypodermic needle can penetrate disc 4b and wall 10. While wall 10 may not be resealable, the rubber material of disc 46 is resealable so that, while a thin film of liquid may find its way into the junction between face 50 and wall 10, it cannot leak out of the system. Referring to Figure 6, an alternative embodiment is shown to provide stronger bonding of the rubber disc to thermoplastic wall 1U of the container. Rubber disc 4ba may be identical to disc 46, while thermoplastic peripheral ^" coating 48a may be identical to coating 4b. However, in this instance, reliance on an edge seal of thermoplastic coating 48a to wall 10 is avoided by an added sleeve 52 made of compatible thermoplastic, for example polyvinyl chloride. Sleeve 52 may carry annular flange 54 which provides a larger, more easily sealed junction area 55 with wall 10. At the same time a large surface area 56 is also provided for sealing between sleeve 52 and thermoplastic coating 48a. This provides a potentially stronger system, for those instances where the construction of Figure 5 exhibits insufficient strength.

A specific, preferred alternative formulation of thermoplastic material to polyvinyl chloride plastic in this invention is a mixture of 20 to 80 percent by weight of glycol modified polyethylene terephthalate and 80 to 20 percent by weight of a flexible block copolymer of poly (butylene terephthalate) and poly (1,4-butylene ether). The resulting material may for example be similar to the compositions disclosed in U.S. Patent No. 4,225,688, but possibly present in different proportions, being heat bondable to polyvinyl chloride and other containers, sets, and the like.

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A preferred formulation for the thermoplastic material surrounding the rubber disc may be a mixture of Eastman PETG 6763 and DuPont HYTREL 4056 in a respective proportion of 35-65 percent to 65-35 percent by weight. Specifically, a mixture of 60 percent by weight of glycol-modified polyethylene terephthalate (PETϋ type 6763) and 40 percent by weight of the flexible block copoly er (e.g. DuPont Hytrel type 4056) may be used. The various sleeves (for example sleeves 18 and 20) and the coated rubber disc can be assembled, and if sleeves 18, 20 are made of polyvinyl chloride and coating 28 is made out of the above-described thermoplastic material or materials similar to it, they can be designed to heat seal together to form the desired sealed injection site during a radio-frequency sealing process. Such seals can survive autoclaving which is conventionally used to sterilize containers of solution for use in the medical field. Such a bond may be optionally made using a solvent.

Also, the bond may be formed between the thermoplastic coating 28 and the compatible surface for sealing by the autoclaving process.

Referring to Figure 4, a portion of an automated process for manufacturing injection site members or similar structures is disclosed. A coil of rubber rod 58 is unwound from spool 60. Rubber rod 58 may be made of polyisoprene and may have a diameter, for example, of 0.295 inch. For example, 100 parts fay weight of NATSYN 2200 or NATSYN 2205, sold by Goodyear Rubber Company, may be mixed with 1.5 parts of dicu yl peroxide as a curing agent and 5 parts by weight of AEROSIL 200 silica, sold by Degussa. This mixture may be extruded into the rubber rod and cured in molten salt (to activate the peroxide) at a temperature of 400° F. for one minute. The rubber rod can then be washed to remove any salt.

Following this, for bonding to polyvinyl chloride thermoplastic, the rubber rod can be exposed to a solution of sodium hypochlorite and hydrochloric acid, to provide a chlorine concentration of 750 to 1000 parts per million, the time of exposure being 30 to 60 seconds. Thereafter the rubber can be

dipped in one percent ammonium hydroxide solution to neutralize the acidic solution and rinsed in water. Thereafter it may be blown dry. The above chlorination process is schematically represented at station 62, where it may be part of a continuous process in accordance with this invention.

Alternatively, prechlorina ed rubber rod can be purchased from various vendors.

Chlorine-treated rubber rod 58 is fed into extruder 64, which may be of a conventional design, to coat rod 58 with an outer coating 66 of polyvinyl chloride plastic which is 0.024 inch thick, the adhesion of which is promoted by the chlorinated surface of rod 58. Rod 58, with its coating 66, is then passed into cooling tank 68 containing water or other cooling medium to sol d fy coating 66, being guided by wheel idler 70 to take up rollers 62. A caterpillar track may be used instead of rollers. Following this, rubber rod 58, having polyvinyl chloride coating 6b, is passed through feed guide station 72 in which caterpillar track type treads 74. Rollers, driven by motor 76, advance rubber rod 58 and its coating 6b, providing the drive means for the entire system. Coated rubber rod 58 is advanced into fly knife type cutter 78, which is driven by cutter motor 80 to cut coated rod 58 up into a continuous stream of injection site members 24, each comprising a rubber disc 26 having peripheral thermoplastic coating 28,. for example. Discs 24 may be collected in a conventional shaker basket, and from there presented to automated machinery for installing injection site members 24 into the bore of a tube as in Figures 2, 3, or 6, or for application to an appropriate surface as in Figure 5, with an automated heat sealing process of bonding for substantially complete automation of the injection site manufacturing process.

Alternatively, rubber rod 58 may be a thermoplastic rubber formulation, for example a block cσpolymer of a rubbery polyolefin and polystyrene such as RATUN or KRATON G sold by

the Shell Chemical Company. Such a rubber rod may be extrusion coated with a coating 66 of polyethylene or other polyolefin, which then may be heat-sealed to a compatible polyolefin sleeve or other surface, typically also made of a polyolefin. It may also be preferred to use the previously described thermoplastic glycol-modified polyester mixed with the block copoly er {e.g. PETG and DuPont Hytrel) for coating 66.

A polyisoprene rubber rod may be extruded without curing; coated with a polyolefin such as polyethylene or poly(ethylene vinyl acetate); and then cured by cross linking the rubber rod, for improved bonding to the polyolefin coating. This curing can be accomplished by an autoclaving step, gamma radiation or electron beam.

When cured, the coated rod would be cut into a plurality of discs normally off-line, then heat impulse sealed into the appropriate receiver.

Accordingly, a sturdy, inexpensive injection site is provided, the manufacture of which may be automated for substantial product improvement at low cost. The above has been offered for illustrative purposes only and is not to be considered as limiting the scope of the invention of this application, which is as defined in the claims below.

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