DE29608344U1 - Dispensing unit with a flexible polymer bag, a connector and an inflexible hard part - Google Patents

Description

1
Description

The invention relates to a dispensing unit with a flexible polymer bag, a connecting part and an inflexible hard part, wherein the connecting part has an inner polymer layer welded to the hard part and an outer polymer layer welded to the inner material of the flexible bag. Such dispensing units are used for storing and dispensing liquids and are in particular physiologically harmless heat-sterilizable bags that are made from transparent polymers, such as polyolefin materials, and have at least one hard part that is sterilizably connected to the bag material via a connecting piece - i.e. the welded connection between the bag and the hard part can easily withstand sterilization temperatures of at least 121°C. The bag should be transparent so that changes in the liquids contained therein, such as flocculation, cloudiness, etc., can be immediately recognized. Such bags are used in medicine, for example, as blood bags, bags for dialysis fluids, plasma, etc., but are also suitable for other aqueous solutions, such as drinks, etc.

Similar flexible containers are already in use thousands of times and were initially mostly made from soft PVC in the state of the art. PVC is cheap because it can be easily sealed with polycarbonate, the usual material for hard parts, and also forms a transparent, flexible film. However, PVC is now undesirable for various reasons. PVC must contain plasticizers in order to be able to offer the required physical properties of flexibility. These plasticizers, e.g. diisooctyl phthalate, have a tendency to migrate out of the PVC and into the liquid in the bag. It can happen that a patient who is dependent on long-term dialysis absorbs several grams of plasticizer over the duration of using such PVC bags, which is physiologically highly questionable and can lead to

can cause permanent damage to the patient. Apart from that, PVC is problematic to dispose of due to the formation of chlorine compounds during combustion and attempts are already being made to replace it with non-halogenated compounds. However, it has so far been very difficult to achieve the favorable properties of PVC, namely the very good and problem-free weldability and transparency with high liquid impermeability and good water vapor barrier properties, with other materials at an economically justifiable cost.

For example, it is known from DE 32 47 294 A 1 to weld bags made of a polyolefin, e.g. polyethylene, to a hard part, e.g. made of polycarbonate, using a hose-like connector, which is a polyethylene copolymerized with vinyl acetate, and then to cross-link this composite using radiation, whereby the connection between the PE of the bag and the PE of the connector becomes sterilization-proof. The polyethylene copolymerized with vinyl acetate begins to flow in the non-cross-linked state at sterilization temperatures, which then makes it necessary to cross-link the entire arrangement that has this material.

Because the weld seam between the connector and the PC part is made first and only then the vinyl acetate/polyethylene copolymer is cross-linked so that the connection can withstand the high sterilization temperatures, the bag is sterilization-proof. However, radiation cross-linking requires considerable effort, since all complete delivery units must be brought to an appropriate radiation source and treated there. +

Furthermore, with this state of the art, the choice of material for the bag is very limited, since a polyolefin that can be welded to the EVA-containing polyolefin is always required as the bag liner.

inner material must be used, otherwise the connection to the PC part and the inside of the bag cannot be guaranteed.

A similar arrangement is known from DE-33 05 365. This describes PVC-free, sterilizable bags with an outer layer made of polyamide, usually PA 66, adhesive and a medium-density polyethylene PE as the inner layer.

These bags are physiologically safe because the polyethylene does not contain any plasticizers and is at least equivalent to PVC bags - however, their production is very complex and the MD polyethylene used is expensive.

From EP 380 270, a 2um tube material for connection to the patient or for introducing additional material into a flexible bag, which can be welded to a polycarbonate hard part if necessary, has become known as a 3-layer tube-like material that can be sealed on the outside with polycarbonate by ultrasound, microwaves or heat.

This sterilizable hose has an outer layer made of polypropylene, ethylene-propylene copolymer or an ethylene-propylene copolymer modified with a thermoplastic elastomer that can be sealed with polycarbonate, while an intermediate layer that makes the connector flexible can be a very low density propylene, ethyl vinyl acetate copolymer, modified or unmodified ethylene-methyl acrylate copolymer, polyvinylidene chloride, ethyl vinyl acetate and modified ethylene-methyl acrylate copolymer, a mixture of ethyl vinyl acetate and very low density polyethylene or a modified ethyl vinyl acetate; the inner layer should have a polymer material that is as heat-resistant as possible, such as a copolyester, polypropylene, ethylene-propylene copolymer, polyurethane, PVC, or a mixture of a copolyester with ethyl vinyl acetate. Preferably, a material is used for the hose that has already been used during coextrusion to improve the temperature.

ture resistance (sterilization) of the weld joint was cross-linked using chemical cross-linkers or can be subsequently cross-linked using radiation, as the material otherwise does not retain its properties under sterilization conditions and flows. This well-known connection part is designed for the external connection with polycarbonate and has a complicated structure - the connection with the flexible bag is. This is therefore not a connection piece, but a hose for liquids that should be connected to the polycarbonate part and of course must be autoclavable.

EP-A-56 42 31 proposes a coextruded connector for the problem of connecting a flexible bag to a polycarbonate rigid part, which provides a polyolefinic polymer material as the outer layer, which has a melt flow index of about 12.

The inner layer is here bound to an intermediate layer that gives the connecting part flexibility and can be SBS, for example, and is designed as an ethyl vinyl acetate-containing connecting layer for attachment to the polycarbonate. This arrangement again requires the usual measure of cross-linking the bag after welding the connecting part, e.g. by radiation, in order to make the arrangement sterilizable.

From DE 44 72 175 (COSTER) it has become known to weld a flexible bag with a multilayer film, which has an outer layer of polyamide or polyester to improve mechanical strength, with an inner layer of polyethylene or polypropylene, to a connecting tube that has an outer layer of polyethylene, polypropylene or the like, since PE and polypropylene can only be welded well to themselves or to each other. Polyacetal is proposed as the hard part to which the inner layer of the connecting part is welded.

However, this arrangement has the disadvantage that it cannot be heat-sterilized.

WO/93/23108 (BAXTER) refers to the problem of a connector for flexible bags with PVC, which is extruded in three layers and has a polypropylene copolymer/styrene/ethylene-butylene-styrene copolymer mixture as the outer layer and an inner layer made of PVC. The use of PVC is, however, usually undesirable for the reasons mentioned above.

In contrast, the invention relates to the problem of connecting multi-layer bags with a polyolefin inner layer to a hard part, whereby these bags should be sterilizable, but the production should be greatly simplified.

The problem is solved by the features of claim 1. Advantageous further developments emerge from the subclaims.

It makes sense for the hard part to be a polymer, such as polycarbonate or a polyacetal.

Because only the inner layer of the connecting part has to be suitable for attachment to the hard part, whereby in the case of the frequently used polycarbonate the corresponding connecting olefin usually has to be cross-linked, in particular radiation cross-linked, it is possible to subject only the connecting parts themselves to the complex cross-linking process, while the bags themselves can be made from inexpensive, relatively thermally stable polyolefins.

This means that the bags no longer have to be transported to the irradiation facility by road, rail, etc., but only the connecting pieces, which also reduces production costs and environmental pollution.

By using the multi-layer tubes according to the invention, polypropylene can be used as the bag material, which naturally has a high melting temperature (140 - 160°C). This means that considerably higher sterilization temperatures can be used, which can also lead to the sterilization times being shortened.

Steam sterilization prevents the inner surfaces from sticking together - this is what enables safe heat sterilization.

In order to avoid sticking of the inner surfaces when PVC or polyethylene was used as the inner layer of the bag, the polyethylene or PVC used previously had to be roughened. With the solution according to the invention, which now uses higher-melting plastics that do not have to be bondable with polycarbonate, the processing steps of roughening can now be avoided and the bag is also more transparent.

It may be necessary to integrate an additional barrier layer into the bag film. Ethylene vinyl alcohol (EVOH) can be used as a barrier layer, which seals very well against oxygen, nitrogen, CO2 and other gases.

Furthermore, thin-film technology can be used to coat another layer (e.g. polyethylene ¹ ]?) with SiOx or aluminum oxide. Of course, as described in the prior art, polyamide/polyethylene composite films can also be used as bags, as before - however, the selection of the connecting parts according to the invention in

By combining with the other materials, radiation cross-linking of the entire bag can be avoided.

It can be advantageous for the flexible bag to contain PVC, polyethylene, polypropylene, polyamide and in particular their compounds, especially those with thermoplastic elastomers, such as SEBS compounds made from them or multilayer composite films made from them, such as polyethylene/ethyl vinyl acetate, PA/polyethylene, polypropylene/SEBS etc. It is advantageous if the bag is manufactured by coextrusion, for example - but all manufacturing processes familiar to the expert can be used.

It is advantageous that the connecting part has an inner layer that forms a heat-sterilizable connection with polycarbonate, such as cross-linked polyethylene with a high ethyl vinyl acetate content.

A dispensing unit according to the invention can be manufactured in such a way that a sterile polymer bag is produced in a manner known per se, for example by coextrusion in the case of a multilayer bag, or the like, independently of this a multilayer polymer connecting part is produced in the form of a tube - for example by coextrusion - whose outer material can be welded to the inner material of the bag and whose inner layer can be welded to the outer material of the hard part, whereby this connecting part can be cross-linked with radiation if necessary in order to make it resistant to sterilization, a hard part is produced from a material that can be welded to the inner material of the connecting part,

and then the hard part is welded to the connecting part and this to the inside of the bag, so that a welded connection is created that can withstand high temperatures, such as normal sterilization temperatures.

Such dispensing units are particularly suitable for the storage of medical liquids, such as

Dialysis fluids, solutions for artificial nutrition, blood, plasma, etc.

Because the combination of bag, connecting part and hard part according to the invention is used, in the special case of sterilizable dispensing units with hard part, it is possible to avoid the laborious radiation cross-linking of the entire bag in order to make the polyolefin used for connection to the hard part resistant to sterilization temperatures, but it is sufficient to cross-link the connecting part, since only this has the cross-linked polyethylene layer with a high ethyl vinyl acetate content, which is required for secure connection to the polycarbonate.

It is also possible to avoid using films with polyamide/polyethylene for the multilayer film bag, whereby special, expensive MD polyethylene is used, which just withstands the sterilization temperature of 121°C, but instead, according to the invention, a simpler, cheaper and more heat-resistant polyolefin can be used as the outer layer of the connecting part and the inner layer of the bag.

The flexible bag preferably comprises PVC, polyethylene, polypropylene, polyamide and compounds thereof or multilayer composite films made of the same, such as polyethylene/ethylene vinyl acetate, polyamide/polyethylene.

The multilayer polymer tube of the connector can, for example, have an outer layer made of polyethylene, PVC, with the multilayer polymer tube and the flexible bag being sealed together.

The invention is explained in more detail below with reference to the drawing, to which, however, it is in no way limited. It shows:

Fig. l: a longitudinal section through the connection area

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a connecting part, hard part and the bag,

Fig. 2: a cross section through the connection area of Fig. 1, and

Fig. 3 is a representation of a complete bag produced according to the invention.

As can be seen from Fig. 1, a preferred embodiment of a dispensing unit according to the invention has a bag made of multilayer film, which has as an inner layer a sealable polyolefin that forms tight seal seams at sterilization temperatures, such as polypropylene or polyethylene, a polypropylene compound or the like.

The connecting part, which is designed here as a two-layer polymer tube, has as outer material 10 a polyolefin that can be welded to the inner layer material 30 of the bag, such as polypropylene or polyethylene, a polypropylene compound or the like, and is welded to the inner layer 30 of the bag film.

The connecting part has as inner layer 11 a high ethyl vinyl acetate compounded polyethylene copolymer, which after radiation cross-linking with a polycarbonate part 20 can be welded in such a way that it forms a sterilization-resistant, liquid-tight weld seam and retains its flexibility and elasticity even after sterilization.

The polycarbonate tube is now welded into the already radiation-cross-linked connection part.

Example 1;

Two-layer hoses with a diameter of

8 mm from an outer layer of a polyethylene compounded with CRATON with a thickness of 0.45 mm and an inner layer with a thickness of 0.5 mm made of polyethylene with a high ethyl vinyl acetate content, co-extruded in a conventional manner as connecting parts. This hose material is then cross-linked by radiation, which gives the inner layer material sufficient temperature resistance of over about 160°C.

Coextruded two-layer bags with an outer layer made of polypropylene and an inner layer made of polypropylene compounded using the same thermoplastic elastomer as the outer layer of the connecting part are then connected to the cross-linked connecting hose using high-frequency welding. A polycarbonate hard part with a pipe attachment is then inserted into the connecting part in a known manner and then sealed with it. The cross-linked polyethylene with a high ethyl vinyl acetate content forms a tight seal that is durable under the thermal conditions of steam sterilization.

Example 2

Two-layer hoses with an outer diameter of 6 mm are coextruded in a conventional manner with an outer layer made of polyethylene with a thickness of about 0.5 mm and an inner layer made of polyethylene with a high ethyl vinyl acetate content with a thickness of about 0.5 mm. This hose material is then cross-linked by radiation, which gives the inner layer material sufficient temperature resistance of its properties of over about 160°C.

Coextruded two-layer bags with an outer layer of polyethylene and an inner layer of polyethylene compounded with an elastomer are then bonded by high frequency welding to the cross-linked connecting tube, which has compounded polyethylene on the outside and

The polycarbonate part is then inserted and sealed in a conventional manner.

Example 3:

Two-layer tubes with an outer diameter of 8 mm and an inner diameter of about 6 mm are coextruded in a conventional manner with a 0.45 mm outer layer of ethyl vinyl acetate polypropylene and a 0.5 mm inner layer of polyethylene with a high ethyl vinyl acetate content. This tube material is then cross-linked by radiation, which gives the inner layer material sufficient temperature resistance of over about 160°C.

Coextruded three-layer bags with an outer layer of 200 u polypropylene, a 200 u thick polypropylene compounded with a thermoplastic elastomer (CAWITON, available from Wittenburg/Bissum/Netherlands) as an intermediate layer and a polypropylene compounded with a higher proportion of thermoplastic elastomer (CAWITON) of approx. 250 u as an inner layer, which were produced by extrusion in a water bath, are then connected by high frequency welding to the cross-linked connecting tube, which has a polypropylene compounded with a thermoplastic elastomer (CAWITON) on the outside and a cross-linked polyethylene with a high ethyl vinyl acetate content on the inside. The polycarbonate part is then inserted and sealed in a conventional manner. Dialysis solutions, e.g. for CAPD, can then be placed in these bags, steam sterilized and stored.

Although the invention has been explained using preferred embodiments, it is by no means limited to these. Rather, the person skilled in the art will be able to come up with any number of further

Implementation forums that fall within the scope of the claims.

Claims (5)

Protection claims 1. Dispensing unit with a flexible polymer bag, a connecting part (10, 11) and an inflexible hard part (20), wherein the connecting part has an inner layer (11) welded to the hard part and an outer polymer layer (10) welded to the inner material of the flexible bag, characterized in that the inner material (30) of the flexible bag and the outer material of the connecting part (10) are the same and are connected in a heat-sterilizable manner. 2. Dispensing unit according to claim ₁₇ , characterized in that the hard part (20) is a polymer, such as polycarbonate, whereby the inner material of the connecting part can be welded thereto to produce a sterilizable weld seam. 3. Dispensing unit according to one of the preceding claims, characterized in that the flexible bag is made of PVC and/or Films made of polyethylene, polypropylene, polyamide and their compounds with thermoplastic elastomers, in particular SEBS compounds thereof or multilayer composite films (30, 31) made of the same, such as PE/EVA, PA/�RΕ, PP/SEBS etc. 4. Dispensing unit according to one of the preceding claims, characterized in that the connecting part has an inner layer forming a heat-sterilizable connection with polycarbonate, such as cross-linked polyethylene with a high EVA content. 5. Dispensing unit according to one of the preceding claims, characterized in that the bag material has an outer layer made of polypropylene and an inner layer made of compounded polypropylene, the connecting part has an outer layer made of compounded polypropylene and an inner layer made of radiation-crosslinked polyethylene with a high EVA content, which is welded to a polycarbonate hard part.