Impermeable flexible multicompartment bag

Abstract: The present invention relates to an impermeable flexible multicompartment bag for medical use for sterile solutions, and to a method for the preparation of such bags. Impermeable flexible multicompartment bags for medical use for sterile solutions for perfusions, consisting of two welded sheets of a composite material wherein the sheets forming the inner wall of the bag consist of a polypropylene and are bonded to an outer layer of a thermoplastic polymer by means of a polyolefin layer, characterized in that the sheets facing the contents of the bags which are made of a homophase copolymer of propylene are immediately welded in the intercompartment region and in the peripheral region such that the weld forming the intercompartment region can be ruptured with a force in the range of from 10 to 30 N while the weld in the peripheral region cannot be ruptured.

Description: The present invention relates to an impermeable flexible multicompartment bag for medical use for sterile solutions, and to a method for the preparation of such bags. In the pharmaceutic industry, and especially in the field of perfusion solutions, impermeable flexible bags are extensively used. Such bags are prepared from polymerized materials which have to meet a wide variety of requirements. Thus, in particular, gas and vapor tightness, transparency, printability and inertness towards the substances they contain are of essential importance. The substances essentially consist of salts and solutions thereof, carbohydrates, amino acids and lipids. They are employed in multicompartment bags, the individual compartments being filled with different components. EP 0 635 254 discloses a multilayered medical film for double compartment container comprising an inner layer of a blend of ethylene-α-olefin copolymer and polypropylene. The inner seals are peelable; a peel force of 10-25 kg is mentioned. DE 44 10 876 A1 relates to a multicompartment bag made of a polymeric material whose bag compartments are formed by welds in the peripheral region and by at least one weld in the intercompartment region, the welds being formed from the polymeric materials facing the compartments. The polymeric materials facing the compartments are inseparably welded together in the peripheral region, and are welded together in the intercompartment region in such a way that the weld can be ruptured with a force in the range of from 5 to 20 N. The different strengths of the bondings are achieved by varying welding temperatures in the welding process. The layer of the multilayer sheet which faces the compartments, referred to herein as the inner layer, essentially comprises two components, namely a matrix polymer and a phase polymer. The system of matrix and phase polymer is also referred to as a matrix-phase polymer system. EP 0 619 998 A1 also describes a multicompartment container with a peeling weld. The multilayer comprises at least one radiofrequency-sensitive layer and one inner layer facing the contents of the compartment which is made of a non-radiofrequency-sensitive material. When the layers are subjected to radiofrequency irradiation, the inner, sensitive layer is heated and can thus be welded with the opposite side. As the materials for the heat-sealable layer, an alloy of styrene-ethylene-butylene-styrene (SEBS) and ethylene-propylene copolymer is described. However, this material is very expensive and therefore only conditionally suitable for a product sold on a large scale. On the other hand, from EP 0 353 193 B1, there is known an impermeable flexible bag for sterile solutions for medical use, in particular a flexible bag for perfusions, characterized by being made of two welded sheets of a multilayer sheet material comprising an 11-aminoundecanoic acid polyamide film bonded by at least one of its faces to a polypropylene film, by means of a polyolefin film, said polypropylene films forming the inner wall of said impermeable flexible bag. Said polypropylene may be either a propylene homopolymer or a copolymerizate of propylene and ethylene. The object of the present invention is to provide an inexpensive impermeable flexible multicompartment bag for medical use which is suitable for subjecting the substances contained therein to heat sterilization at 121°C, especially to provide a bag which does not require a over bag for clinical applications. According to the invention, it has been found that, when defined conditions are observed, a composite material made of a homophase polypropylene copolymer which is bonded to an outer layer of a thermoplastic polymer by means of a polyolefin layer can be used to prepare a suitable impermeable flexible multicompartment bag having a weld in the intercompartment region which can be ruptured with a force in the range of from 10 to 30 N while the weld in the peripheral region cannot be ruptured. Accordingly, in a first embodiment of the present invention, impermeable flexible multicompartment bags for medical use for sterile solutions for perfusions consist of two welded sheets of a composite material, wherein the sheets forming the inner wall of the bag consist of a polypropylene and are bonded to an outer layer of a thermoplastic polymer by means of a polyolefin layer, characterized in that the sheets facing the contents of the bags which are made of a homophase copolymer of propylene are immediately welded in the intercompartment region and in the peripheral region such that the weld forming the intercompartment region can be ruptured with a force in the range of from 10 to 30 N while the weld in the peripheral region cannot be ruptured. If the weld in the intercompartment region can be ruptured with too weak a force, a safe separation of the contents of the compartments during storage and shipping is not ensured since the intercompartment region will then be opened by small mechanical actions already. However, if the force required for opening the parting weld is too strong, it may be difficult for the hospital staff to open this parting region. In addition, there is a risk that the bag will break somewhere else. The multicompartment bags according to the invention can be filled in a simple manner without the risk of premature mixing of the components. In addition, it has been found that the multicompartment bags according to the invention can be sterilized at a temperature of 121°C without any problem. An essential realization with the present invention is that particles of the plastic material were not found in the sterile solution after opening the intercompartment region. The rupture strength of the weld is sufficiently high for the bags to exhibit a safe breaking resistance when dropped from a height of 1.50 m and a good breaking resistance when dropped from a height of 2.00 m. The multicompartment bags according to the invention are easily prepared since the usual breaking seals for the separation of the individual compartment regions which have been usual to date are not necessary. This provides the advantage of a quick and thorough mixing of the components after opening. For the preparation of the multicompartment bags, per se known sheet blowing or tube blowing methods can be employed as is known, especially, from EP 0 353 193 B1. As usual in the prior art, the multicompartment bags according to the invention contain at least one connection piece in at least one compartment in the weld of the peripheral region wherein such connection piece can be designed as an inlet and/or outlet connection piece. Of course, the multicompartment bags according to the invention may also have suspension means per se known in the prior art, which may be designed, for example, in the form of an opening in the weld lying opposite the outlet connection piece. The rupturable weld in the intercompartment region can be ruptured, for example, by applying pressure to at least one of the adjacent compartments. This may be done, for instance, with the flat of the hand. If the compartments are not completely filled and firm, it is also possible, in addition, to rupture the rupturable weld in the intercompartment region by tearing opposite surfaces of a compartment apart. In a particular embodiment of the present invention, the multicompartment bags comprise at least three compartments for separately containing carbohydrates, lipids and electrolytes. Similarly, it is particularly preferred that the multicompartment bags are designed to comprise four compartments for separately containing carbohydrates, lipids, electrolytes and vitamins, wherein the components are preferably arranged in the compartments in the way as illustrated in DE 196 05 357. The homophase copolymer of propylene is a per se known material and is appreciated in many fields. For the bag according to the present invention, a polymer having a melting point in the range of 150 to 160°C is preferably employed. For example, the homophase copolymer of propylene which is obtainable under the designation Appryl 3020 SM3 and contains about 3% by weight of polyethylene can be employed to particular advantage since this material is well suitable for opening the peeling weld after injection molding. This polypropylene is essentially impermeable to water vapor, a quality which is advantageously combined with those of the thermoplastic polymer of the outer sheet. According to the invention, the multilayer material of the bags can be combined in a wide variety of ways as compared with other complex materials: it can be prepared by coextrusion, a preparation process which is more advantageous than co-rolling; it enables unobjectionable steam sterilization at 121°C while other materials of the prior art will more or less gradually decompose at this temperature. For welding the peripheral region, the welding head of the selected device can be maintained at a temperature sufficient to melt the polypropylene sheet without modifying the outer thermoplastic sheet which should have a melting point above the welding temperature and thus forms a protective film. A number of such materials are known to those skilled in the art, for example, EVOH, PVDC or various polyamides. Thus, it is possible to prepare the multicompartment bag of the present invention by coextruding the polypropylene, the selected polyolefin binder and the thermoplastic polymer, i.e. directly from the corresponding pellets without prior preparation of the individual sheets. For this purpose, known sheet blowing or tube blowing techniques are advantageously employed. The use of double outer and polypropylene films enables a considerable increase in the mechanical resistance of the sheets which thus form multilayer materials of the bags according to the invention. Particularly preferred thicknesses of the individual sheet layers are known from the prior art and need not be changed according to the invention. Special attention is to be drawn to the intercompartment region. While a stable hot-sealed weld is desired in the peripheral region, it is required according to the present invention that the intercompartment region have a lower strength than the peripheral region. In this connection, it is suggested in DE 44 10 876 A1 that the molecular structure of the inner layer of the multilayer sheet has chain regions which require much heat and, in other regions, significantly less heat (energy uptake) for the excitation of vibrations. This heterophase structure is supposed to cause that welding at a lower temperature will only melt those regions which require a low energy uptake for melting. This is called partial melting. In contrast, at the higher temperature, both the regions which require a low energy uptake and the regions which require a high energy uptake will melt. A more or less complete melting of the inner layer occurs, in particular in the peripheral region. Such different melting behavior is ensured by a different temperature control in the welding of the different welds. According to the invention, however, the molecular structure of the inner layer of the multicompartment bags does not contain any chain regions which require a high (heat) energy uptake and, in other regions, significantly lower energy uptake for the excitation of vibrations. Rather, a weld having the desired characteristics is formed by exactly adjusting the temperature in the intercompartment region to below the melting temperature of the homophase polypropylene copolymer. Thus, another aspect of the present invention is a method for the preparation of the above defined multicompartment bags, the method being characterized in that the intercompartment region of the sheet is welded at a temperature below the welding temperature of the peripheral region, in particular below the melting temperature or melting range of the polypropylene which froms the inner wall of the container. Homophase copolymer of propylene is a thermoplastic material and thus, of course, has no exact melting point. However, by differential thermogravimetric analysis or other analogous methods, it is possible to determine the maximum/minimum in the melt transition curve. According to the invention, it has now been found that, for achieving rupturability of the intercompartment region, it is required that the welding of the intercompartment region be performed at a temperature significantly below the minimum of the melting range of the polypropylene, in particular at a temperature of 10 to 20°C below the melting range of the polypropylene. Particularly preferred is a temperature of above 136°C, especially in the range of 137.5°C ± 1°C. Of course, this is supposed to mean the temperature of the melting electrode. Temperatures of below 136°C involve the risk that the weld in the intercompartment region already tears during the filling of the contents since the latter are washed into the compartments in part at a high liquid pressure. In a sterility test, it could be established that no problems occurred in the storage, shipping and opening of the peeling weld with multicompartment bags the intercompartment regions of which were hot-sealed at a temperature of 136.5°C. Irrespective of the temperature of the hot-sealing step of the intercompartment region, it could be found no instance in which particles entered the solutions from the opening of the intercompartment region.

Claims: Impermeable flexible multicompartment bags for medical use for sterile solutions for perfusions, consisting of two welded sheets of a composite material wherein the sheets forming the inner wall of the bag consist of a polypropylene and are bonded to an outer layer of a thermoplastic polymer by means of a polyolefin layer, characterized in that the sheets facing the contents of the bags which are made of a homophase copolymer of propylene are immediately welded in the intercompartment region and in the peripheral region such that the weld forming the intercompartment region can be ruptured with a force in the range of from 10 to 30 N while the weld in the peripheral region cannot be ruptured. The multicompartment bags according to claim 1, comprising at least three compartments for separately containing carbohydrates, lipids and electrolytes. The multicompartment bags according to claim 1, comprising at least four compartments for separately containing carbohydrates, lipids, electrolytes and vitamins. A method for the preparation of multicompartment bags according to one or more of claims 1 to 3, characterized in that the intercompartment region is welded at a temperature below the melting range of the peripheral region, in particular at a temperature below the melting range of the sheets forming the inner wall of the bag. The method according to claim 4, characterized in that the intercompartment region is welded at a temperature of above 136°C, especially in the range of 137.5°C ± 1°C.

Inventors: CHATTOT RAOUL, DJOKIC SARA, LORETTI MAURICE, CHATTOT, RAOUL, DJOKIC, SARA, LORETTI, MAURICE
Applicants: BRAUN MELSUNGEN AG, B. BRAUN MELSUNGEN AG
Application year: 1998
Main classification: A61J1
IPC codes: A61J1, B29C65, B65D81