Flexible heat-sterilizable non-PVC multi-layer film for medical packaging

Description

[0001] The invention relates to heat-sterilizable multilayer films containing aliphatic polyolefins, a process for their production, and their use in the manufacture of medical packaging, as well as medical packaging containing such multilayer films. The multilayer films are steam sterilizable and, when used for medical packaging, are characterized by a low adsorption tendency for drugs or medical solutions, a temperature-resistant outer layer, and sufficient adhesion between the individual layers.

[0002] Multilayer films have found a wide range of applications for many years, e.g. in the food industry but also in the medical / pharmaceutical sector, for example as secondary packaging (outer packaging) or primary packaging for solution sachets, dry concentrates and medications in tablet form.

[0003] Some multilayer films can be processed into flexible packaging, suitable, for example, as pouches for packaging and administering medical solutions. It is currently common practice for medical solutions, such as infusion solutions for parenteral administration, to be available on the market in flexible, single-use pouches made of polyvinyl chloride (PVC) or non-PVC materials.

[0004] Elastic PVC materials pose a health risk because they contain plasticizers that can be released. Therefore, efforts are being made to replace PVC with non-PVC materials.

[0005] In addition to the ability to collapse, which ensures complete drainage of the bag, flexible medical bags must also meet other performance criteria such as transparency, heat sterilization capability at 121°C, sufficient mechanical strength, especially under dynamic stress in the weld seam area, good water vapor barrier, load-bearing capacity for common pressure cuff applications e.g. pressure infusions, and, from a pharmaceutical point of view, minimal influence of the packaging on the bag contents.

[0006] Multilayer films with a layer structure based on polyolefins have proven advantageous with regard to these requirements.

[0007] DE-A 10361851 and WO 2020 / 127227 A1 describe a heat-sterilizable, three-layer multilayer film for the production of medical pouches. The outer layer consists of polypropylene homopolymer modified with impact modifiers, the middle layer of polypropylene terpolymer modified with impact modifiers, and the inner layer of polypropylene terpolymer and / or polypropylene copolymer modified with impact modifiers. Suitable impact modifiers include styrene block copolymers (e.g., SEB) and ethylene / α-olefin copolymers. Exemplary films have a middle layer of 75 wt.% PP terpolymer, 20 wt.% SEBS block copolymer and 5 wt.% PE plastomer (ethylene / octene copolymer), and an inner layer of 85 or 75 wt.% PP terpolymer, 15 or 20 wt.% SEB block copolymer and 0 or 5 wt.% PE plastomer.

[0008] DE 203 20 212 A1 describes a heat-sterilizable 3-layer multilayer film produced by coextrusion for use in medical pouches. Exemplary films have an outer layer of 97 wt.% polypropylene homopolymer and 3 wt.% SEBS block copolymer, a middle layer of 80 wt.% EXCELLEN – a heterophasic copolymer based on polypropylene and polyethylene – and 20 wt.% SEBS block copolymer, and an inner layer of 75 wt.% PP terpolymer, 20 wt.% SEBS block copolymer, and 5 wt.% PE plastomer.

[0009] KR-A 2010-0101332 discloses multilayer films with excellent adhesion between the layers, produced by coextrusion of a polypropylene layer and a polyethylene layer, wherein the polypropylene layer is a blend with polyethylene (40 to 50 wt.%) or the polyethylene layer is a blend with polypropylene (20 to 50 wt.%).

[0010] EP-A 2231775 relates to a multilayer film for use as a container for medical solutions, comprising preferably an outer layer of propylene homopolymer; a middle layer of 30 to 70 wt.% propylene-based polymer (e.g. propylene-ethylene-butene terpolymer) and 30 to 70 wt.% thermoplastic elastomer (e.g. SEBS); and an inner layer of 50 to 70 wt.% propylene copolymer, 5 to 20 wt.% polyethylene (e.g. HDPE), and 10 to 45 wt.% thermoplastic elastomer (e.g. SEBS).

[0011] EP-A 0229475 describes a multilayer film for medical containers, preferably 3-layered, comprising (a) a first (= inner) heat-sealable layer of a blend preferably consisting of 40 to 70 wt.% propylene copolymer, 10 to 40 wt.% ethylene-propylene or ethylene-1-butene copolymer (1-butene content preferably 5 to 15 wt.%), and 5 to 35 wt.% elastomer (e.g., ethylene copolymer, styrene block copolymer); (b) a second (middle) layer of a blend of (i) polyethylene (HDPE) (50 to 90 wt.%) and (ii) a modifier; and (c) a third (outer) layer of a blend of (i) polypropylene and (ii) a modifier.

[0012] JP-A 2007 / 245490 describes a heat-sterilizable multilayer film for use in medical pouches, comprising an inner high-density layer (0.89 to 0.93 g / cm³) of a blend of an ethylene / α-olefin copolymer produced using a metallocene catalyst and HDPE (10 to 40 wt%), and an outer layer of a propylene polymer.

[0013] US 2012 / 0034404 A1 describes a multilayer film for medical packaging (e.g., pouches) comprising: an outer layer comprising preferably a propylene homopolymer; a middle layer comprising 10 to 60 wt.% of a propylene copolymer and 40 to 90 wt.% of a thermoplastic elastomer; and an inner layer comprising: 60 to 80 wt.% of a propylene copolymer, 10 to 30 wt.% polyethylene, and 1 to 10 wt.% of a thermoplastic elastomer. The polyethylene is preferably a copolymer of ethylene and an α-olefin with a melting point of 50 to 120°C (examples: 60°C); preferably, the propylene copolymer is a propylene-ethylene-butene terpolymer. A hydrogenated styrene block copolymer is preferably used as the thermoplastic elastomer.

[0014] The multilayer films according to the state of the art still require improvement, particularly with regard to the adhesion between the individual layers and the requirements for hot steam sterilizability at 121°C.

[0015] The object of the present invention is therefore to provide a flexible, heat-sterilizable multilayer film for medical purposes which has good adhesion between the individual layers and good impact strength, and furthermore exhibits a low tendency for the adsorption of drugs or medical solutions on the surface (inner layer) facing the drug or medical solution, and which can be processed into medical containers (e.g. bags) by simple methods.

[0016] An object of the invention is a heat-sterilizable multilayer film comprising (consisting of) a) comprising (consisting of) a first polymer layer (A) comprising at least one, preferably one, propylene homopolymer modified with at least one, preferably one, impact modifier; b) comprising a second polymer layer (B) (consisting of): B1) 60 to 85 wt.% - based on (B) - of a homogeneous composition (= "composite") (B1) comprising: B11) 65 to 85 wt.% - based on (B1) - ethylene homopolymer, and B12) 15 to 35 wt.%, preferably 20 to 30 wt.%, - based on (B1) - at least one ethylene copolymer comprising as a comonomer at least one, preferably one, alpha-olefin having 4 to 12, preferably 4 to 8, particularly preferably 4 to 6 carbon atoms, preferably selected from 1-butene, 1-pentene, 1-hexene and 4-methyl-1-pentene, preferably 1-butene, and wherein composition (B1) has a melting point of > 125°C and a density of 945 to 960 kg / m³ < has a weight of 11 to 30 kg / m³; B2) 11 to 30 kg.-% - based on (B) - at least one propylene terpolymer; B3) 4 to 15 wt.% - based on (B) - at least one polyethylene elastomer, which is a copolymer of ethylene with at least one, preferably one, alpha-olefin having 4 to 12, preferably 7 to 12, carbon atoms; c) a middle polymer layer (C) located between the first polymer layer (A) and the second polymer layer (B), comprising (consisting of): C1) 61 to 80 wt.%, preferably 65 to 80 wt.%, - based on (C) - at least one propylene terpolymer; C2) 15 to 25 wt.% - based on (C) - at least one styrene block copolymer elastomer; C3) 4 to 14 wt.%, preferably 4 to 10 wt.%, - based on (C) - at least one polyethylene elastomer, which is a copolymer of ethylene with at least one, preferably one, alpha-olefin containing 4 to 12 carbon atoms.

[0017] The proportions given in weight percent (wt%) each add up to 100 wt%.

[0018] For the purposes of the present invention, the structural units of a monomer in a (co)polymer are understood to be the structural units derived from the incorporated monomer.

[0019] The term "heat sterilizable" means that the materials in question can be subjected to sterilization at elevated temperatures, preferably steam sterilization. Sterilization refers to processes by which materials and objects are freed from living microorganisms. The resulting state of the materials and objects is described as "sterile." Steam sterilization of filled or unfilled medical packaging uses hot steam, typically performed in an autoclave. The medical packaging is preferably heated in the steam for 20 minutes at 121 °C and 2 bar pressure. The air inside the autoclave is completely replaced by steam.

[0020] The term "multilayer film" refers to thermoplastic materials in several co-extruded polymer layers that are joined together to form a film in the form of a continuous web or tube.

[0021] The term "impact modifier" refers to polymeric materials, such as styrene block copolymer elastomers, polyethylene elastomers and polypropylene elastomers, which, when mixed in the molten state, improve the impact strength of the polymer surrounding the impact modifier.

[0022] The term "impact strength" refers to a material's ability to withstand dynamic stress. According to the standard DIN EN ISO 180:2013-08, the impact strength of plastics can be measured under specified conditions.

[0023] A "homogeneous composition" is understood to be a composite of substances (components) mixed at the molecular level, which together form a single phase.

[0024] The "melting temperature" (softening temperature, T m ) is usually determined using DSC (Differential Scanning Calorimetry).

[0025] The "density" can be determined using the liquid pycnometer according to DIN EN ISO 1183-1 (2019-09) - Method B). First polymer layer (A)

[0026] The first polymer layer (A) of the multilayer film according to the invention is, by definition, the polymer layer that is located on the outside of the packaging when the film is processed into a package, which is preferably a bag. Therefore, during further processing of the film into packaging, it is in direct contact with the surface of the welding tool and thus preferably requires a high melting or softening temperature, which is preferably above 125°C, particularly preferably between 127°C and 150°C, and most preferably between 130°C and 145°C.

[0027] The first polymer layer (A) contains at least one, preferably one, polypropylene homopolymer which is modified with at least one, preferably one, impact modifier.

[0028] Preferably the first polymer layer (A) consists of at least one, preferably one, polypropylene homopolymer which is modified with at least one, preferably one, impact modifier.

[0029] Furthermore, the first polymer layer (A) preferably contains a polypropylene homopolymer which is modified with an impact modifier.

[0030] The first polymer layer (A) contains (or consists of) at least one, preferably one, propylene homopolymer (polypropylene), which is generally modified with 1 to 30 wt.%, preferably with 2 to 20 wt.%, particularly preferably 2 to 10 wt.%, in particular 3 to 5 wt.%, of at least one impact modifier to improve (cold) impact strength.

[0031] The production of propylene homopolymers is known. Furthermore, propylene homopolymers are commercially available, e.g., from LyondellBasell Corporation, USA.

[0032] Preferably, the first polymer layer (A) contains (or consists of) a propylene homopolymer modified with at least one impact modifier selected from the group of styrene block copolymers such as styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene-propylene-styrene block copolymer (SEEPS), styrene-isoprene-styrene block copolymer (SIS) and styrene-butadiene-styrene block copolymer (SBS), preferably SEBS and SEPS, in particular SEBS, and / or from the group of copolymers of ethylene with at least one alpha-olefin having 4 to 12, preferably 4 to 8 carbon atoms, such as ethylene-butylene copolymers and / or ethylene-1-octene copolymers.

[0033] Particularly preferably, the first polymer layer (A) contains (or consists of) 90 to 98 wt.%, in particular 95 to 97 wt.%, of a propylene homopolymer and 2 to 10 wt.%, in particular 3 to 5 wt.%, of a styrene block copolymer and / or a copolymer of ethylene with at least one alpha-olefin having 4 to 12, preferably 4 to 8 carbon atoms.

[0034] In a preferred embodiment, the first polymer layer (A) contains (or consists of) 95 to 97 wt.% of a polypropylene homopolymer and 3 to 5 wt.% of a styrene-ethylene / butylene block copolymer.

[0035] The weight specifications for the components of the first polymer layer (A) refer to the total weight of the first polymer layer (A). Second polymer layer (B)

[0036] The second polymer layer (B) is, by definition, the polymer layer located on the inside of the packaging when the multilayer film according to the invention is processed into a package, which is preferably a bag. This polymer layer is responsible for ensuring that the packaging can be tightly sealed by welding. The second polymer layer (B) of the film must be reliably weldable to itself and to appropriately inserted port elements at the lowest possible temperature and welding time, while still being heat-sterilizable at temperatures above 121°C. A low welding temperature is particularly important to minimize the stresses placed on the film structure. Accordingly, the melting or softening temperature of the second polymer layer (B) is generally above 121°C, preferably between 122°C and 135°C, and particularly preferably between 124°C and 130°C, but in any case below the melting or softening temperature.Softening temperature of the first polymer layer (A).

[0037] The second polymer layer (B) of the multilayer film according to the invention contains (or consists of) the components B1), B2) and B3) in the following proportions (each based on (B)): B1) 60 to 85 wt.%, preferably 65 to 80 wt.%, particularly preferably 72 to 78 wt.%, B2) 11 to 30 wt.%, preferably 15 to 25 wt.%, particularly preferably 17 to 22 wt.%; B3) 4 to 15 wt.%, preferably 4 to 12 wt.%, particularly preferably 5 to 10 wt.%. Component B1)

[0038] Component B1) serves to reduce the tendency for delamination between the second polymer layer (B) and the middle polymer layer (C).

[0039] The homogeneous composition (= "Composite") (B1) consists of: B11) 65 to 85 wt.% - based on (B1) - ethylene homopolymer, and B12) 15 to 35 wt.%, preferably 20 to 30 wt.%, - based on (B1) - at least one, preferably one, ethylene copolymer, which contains as a comonomer at least one, preferably one, alpha-olefin having 4 to 12, preferably 4 to 8, particularly preferably 4 to 6 carbon atoms, most particularly preferably selected from 1-butene, 1-pentene, 1-hexene and 4-methyl-1-pentene, preferably 1-butene.

[0040] The homogeneous composition (B1) has a melting temperature of > 125°C, preferably of 130 to 135°C, and a density of 945 to 960 kg / m 3<.

[0041] The ethylene copolymer B12) contains no other comonomers besides the alpha-olefin with 4 to 12 carbon atoms.

[0042] The proportion of the alpha-olefin comonomer – based on (B12) – is generally 25 to 40 wt.%, preferably 30 to 37 wt.%; the ethylene proportion – based on (B12) – is accordingly 60 to 75 wt.%, preferably 63 to 70 wt.%. The weight percentages refer in each case to the polymerized structural units of the monomers in the ethylene copolymer (B12).

[0043] Preferably, component B1) is a homogeneous composition consisting of: B11) 70 to 80 wt.% - based on (B1) - ethylene homopolymer, and B12) 20 to 30 wt.% - based on (B1) - at least one, preferably one, ethylene copolymer, which contains as comonomer at least one, preferably one, alpha-olefin selected from 1-butene, 1-pentene, 1-hexene and 4-methyl-1-pentene, preferably 1-butene.

[0044] Component B1) is particularly preferred as a homogeneous composition consisting of: B11) 70 to 80 wt.% - based on (B1) - ethylene homopolymer, and B12) 20 to 30 wt.% - based on (B1) - ethylene-1-butene copolymer, wherein the proportion of 1-butene - based on (B12) - is 25 to 40 wt.%, preferably 30 to 37 wt.%.

[0045] As ethylene homopolymer B11), a high-density polyethylene (HDPE) is generally used, preferably an HDPE with a density of 950 to 970 kg / m 3< .

[0046] The production of HDPE is well known to experts.

[0047] Furthermore, HDPE is commercially available; HDPE with a density of 950 to 970 kg / m 3< is available, for example, from Tosoh Co., Ltd. as Nipolon ®< Hard or from Borealis as Bormed ®< HE2581-PH and Bormed HE7541-PH.

[0048] The ethylene copolymer B12) is typically prepared by copolymerization of ethylene and the alpha-olefin comonomer using a metallocene catalyst. Suitable metallocene catalysts are organic compounds of a transition metal with several ligands (the number corresponding to the oxidation state of the transition metal) coordinated to the transition metal, at least one of which is a cyclopentadienyl group. The transition metal is preferably selected from the group consisting of Zr, Ti, Hf, V, Nb, Tn, and Cr; Zr or Hf is particularly preferred, and Zr is most preferably preferred.

[0049] A Zr or Hf metallocene catalyst with two cyclopentadienyl residues is preferred.

[0050] The metallocene catalyst bis(n-butyl-cylopentadienyl)-zirconium dichloride is particularly preferred.

[0051] For the production of the ethylene copolymer B12, the aforementioned metallocene catalysts are used as ionic complex compounds, which can be obtained by reacting the metallocene catalyst with organically modified alumina. All common clay materials can be used as alumina; hectorite, smectite, and montmorillonite are preferred.

[0052] The organically modified alumina is obtained by reacting alumina with an aliphatic salt. Examples of such an aliphatic salt are N,N-dimethyldecylamine hydrochloride, N,N-dimethyldodecylamine hydrochloride, N,N-dimethyltetradecylamine hydrochloride, N,N-dimethylhexadecylamine hydrochloride, N,N-dimethyl octadodecylamine hydrochloride, N,N-dimethyl behenylamine hydrochloride, N,N-dimethyl behenylamine hydrofluoride, N,N-dimethyl behenylamine hydrobromide, and N,N-dimethyl behenylamine hydroiodide; N,N-dimethyl behenylamine hydrochloride is preferred.

[0053] Preferably, an organoaluminium compound, preferably triisobutylaluminium, is used as a co-catalyst for the production of the ethylene copolymer B12).

[0054] The production of the ethylene copolymer B12) can be carried out in the presence of the metallocene catalyst, for example by a slurry process, a solution process or in the gas phase.

[0055] The production of ethylene-alpha-olefin copolymers using such a metallocene catalyst is described, for example, in JP-A 2019 / 111805 and JP-A 2019 / 167430.

[0056] Ethylene copolymer B12) is a high-density ethylene copolymer. Preferably, ethylene copolymer B12) has a density of 945 to 960 kg / m³. Component B2)

[0057] Component B2) is at least one, preferably one, propylene terpolymer.

[0058] The term "terpolymer" refers to a copolymer made from three different monomers.

[0059] The term "propylene terpolymer" refers to a polypropylene molecular chain modified with two additional co-monomers during the polymerization process. Preferred additional co-monomers are ethylene and / or at least one C4-C12 α-olefin, preferably a C4-C8 α-olefin, particularly preferably ethylene and a C4-C8 α-olefin, and most preferably ethylene and 1-butene.

[0060] The proportion of ethylene is preferably 1 to 4 wt.%, and the proportion of the at least one C4-C8 α-olefin, in particular 1-butene, is preferably 9 to 12 wt.%, each based on (B2). The weight percentages refer to the polymerized structural units of the monomers in the terpolymer (B2).

[0061] Propylene terpolymer (B2) composed of structural units of propylene, ethylene and butylene is particularly preferred.

[0062] The production of propylene terpolymers is known. Furthermore, suitable propylene terpolymers are commercially available, e.g., from Borealis, Austria. Component B3)

[0063] Component B3) is at least one, preferably one, polyethylene elastomer, which is a copolymer of ethylene with at least one, preferably one, alpha-olefin having 4 to 12, preferably 7 to 12, most preferably 8 carbon atoms.

[0064] Ethylene / alpha-olefin copolymers B3) preferably have a density in the range of 600 to 950 kg / m 3< , particularly preferably 750 to 900 kg / m 3< .

[0065] The proportion of the polymerized structural units of the alpha-olefin - based on (B3) - is more than 8 wt.%, preferably more than 10 wt.%, in particular 20 to 30 wt.%.

[0066] Component B3) is preferably an ethylene-1-octene copolymer.

[0067] Suitable polyethylene elastomers are commercially available, e.g. from Dow Chemical Company, USA.

[0068] Preferably, the second polymer layer (B) according to the invention contains (or consists of) a homogeneous composition (component B1) consisting of B11) 70 to 80 wt.% high-density polyethylene and B12) 20 to 30 wt.% ethylene-1-butene copolymer, a propylene terpolymer (component B2) composed of structural units of propylene, ethylene and butylene (component B2), and an ethylene-1-octene copolymer (component B3).

[0069] Particularly preferably, the second polymer layer (B) according to the invention contains (or consists of) 65 to 80 wt.%, preferably 72 to 78 wt.% of the homogeneous composition (component B1) consisting of (B11) 70 to 80 wt.% high-density polyethylene and (B12) 20 to 30 wt.% ethylene-1-butene copolymer, 15 to 25 wt.%, preferably 17 to 22 wt.% propylene terpolymer (component B2) composed of structural units of propylene, ethylene and butylene (component B2), and 4 to 12 wt.%, preferably 5 to 10 wt.% ethylene-1-octene copolymer (component B3).

[0070] The weight specifications for components B1), B2) and B3) of the second polymer layer (B) refer to the total weight of the second polymer layer (B). Middle polymer layer (C)

[0071] The middle polymer layer (C) has the largest mass fraction (at least 50 wt.%) of the multilayer film, preferably 60 to 95 wt.%, particularly preferably 70 to 90 wt.%, most preferably 75 to 85 wt.% of the total multilayer film and serves to improve the impact strength of the entire structure.

[0072] The middle polymer layer (C) of the multilayer film according to the invention contains (or consists of) the components C1), C2) and C3) in the following proportions (each based on (C)): C1) 61 to 80 wt.%, preferably 65 to 75 wt.%, C2) 15 to 25 wt.%, preferably 17 to 22 wt.%, C3) 5 to 19 wt.%, preferably 8 to 17 wt.%. Component C1)

[0073] Component C1) is at least one, preferably one, propylene terpolymer. Propylene terpolymer C1) is defined in the same way as component B2); reference is made to the corresponding descriptions of component B2). Component C2)

[0074] Component C2) is at least one, preferably one, styrene block copolymer (SBC) elastomer.

[0075] The term "styrene block copolymer elastomer" refers to synthetic thermoplastic elastomers based on styrene block copolymers, which are used as impact modifiers.

[0076] The at least one styrene block copolymer (SBC) elastomer B2) is preferably selected from the group consisting of: styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene-ethylene-propylene-styrene block copolymer ( SEEPS ), Styrene-isoprene-styrene block copolymer (SIS) and styrene-butadiene-styrene block copolymer (SBS), preferably SEBS and SEPS, in particular SEBS.

[0077] Suitable styrene block copolymer (SBC) elastomers (C2) are commercially available, e.g., from Asahi Kasei, Japan.

[0078] It is also possible to partially replace the styrene block copolymer (SBC) elastomer with one or more thermoplastic olefin-based elastomers (TPE-O) (proportion of TPE-O: maximum 45 wt.%, preferably 20 to 30 wt.%).

[0079] Component C2) is preferably a styrene block copolymer (SBC) elastomer which does not contain any portion of an olefin-based thermoplastic elastomer. Component C3)

[0080] Component C3) is at least one, preferably one, polyethylene elastomer, which is a copolymer of ethylene with at least one alpha-olefin having 4 to 12, preferably 4 to 8 carbon atoms.

[0081] Ethylene / alpha-olefin copolymers (C3) generally have a density in the range of 440 to 860 kg / m 3< .

[0082] The proportion of the polymerized structural units of the alpha-olefin - based on (C3) - is more than 8 wt.%, preferably more than 10 wt.%, in particular 20 to 30 wt.%.

[0083] Component C3) is preferably an ethylene-1-butene copolymer, an ethylene-1-hexene copolymer or an ethylene-1-octene copolymer, particularly preferably an ethylene-1-octene copolymer.

[0084] Suitable polyethylene elastomers are commercially available, e.g. from Dow Chemical Company, USA.

[0085] Preferably, the middle polymer layer (C) according to the invention contains (or consists of) a propylene terpolymer (component C1)) composed of structural units of propylene, ethylene and butylene, a styrene-ethylene-butylene-styrene block copolymer (SEBS) (component C2)), and an ethylene-octene copolymer (component C3)).

[0086] Particularly preferably, the middle polymer layer (C) according to the invention contains (or consists of) 65 to 80 wt.%, preferably 72 to 78 wt.%, propylene terpolymer (component C1)) composed of structural units of propylene, ethylene and butylene; 17 to 22 wt.%, preferably 19 to 21 wt.%, styrene-ethylene-butylene-styrene block copolymer (SEBS) (component C2); and 4 to 10 wt.%, preferably 5 to 8 wt.%, ethylene-octene copolymer (component C3). Functional layer (D)

[0087] The heat-sterilizable multilayer film according to the invention can further comprise an additional functional layer D) as an outer layer, which is located adjacent to the first polymer layer (A) on the outer side of (A) (i.e. on the other side of (A) opposite the one with polymer layer (C)).

[0088] The functional layer (D) preferably ensures that the heat-sterilizable multilayer film, as well as packaging made from it such as medical pouches or film tubes made from it, are gas-tight and / or waterproof.

[0089] Functional layer D) contains, preferably consists of, at least one, preferably one, material selected from the group consisting of: ethylene-vinyl alcohol copolymers, polyvinyl alcohols, polyamides, liquid crystal polymers (LCP), aromatic polyesters, preferably terephthalic acid polyesters, particularly preferably polyethylene terephthalates (PET), silicon dioxide (SiO₂ x₅), aluminum oxide (AlO₂ x₅), and acrylate-based polymers.

[0090] Preferably the functional layer (D) consists of PET / SiO x .

[0091] The functional layer (D) preferably has a layer thickness of 5 to 25 µm, in particular of 10 to 20 µm.

[0092] By means of a functional layer (D) made of PET / SiO x, the gas barrier (e.g. the oxygen barrier) of the heat-sterilizable multilayer film according to the invention is significantly improved, so that the film is also well suited for the storage of oxygen-sensitive ingredients.

[0093] By means of a SiO x / PET functional layer (D) the oxygen barrier (oxygen transmission rate (OTR)) of the heat-sterilizable multilayer film according to the invention can be reduced by a factor of 1000 to OTR values ​​< 1 cm 3< / (m 2< x day) ASTM F1927 (23°C, 50% rH). Multilayer film

[0094] Preferably, the heat-sterilizable multilayer film according to the invention consists of the polymer layers (A), (B) and (C).

[0095] The multilayer film may contain in each of the polymer layers (A), (B) and (C) common additives and / or processing aids suitable for the intended use of the multilayer film in common quantities.

[0096] Preferred additives are antioxidants and thermal stabilizers (phosphitic and phenolic stabilizers such as Irgafos ®< 168, Irgafos P-EPQ, Irganox ®< 1076 or Irganox 1010), as well as acid scavengers such as DHT-4A ®< , synthetic hydrotalcite (SHT) and magnesium oxide (MgO).

[0097] Preferably, the heat-sterilizable multilayer film made of polymer layers (A), (B) and (C) according to the invention contains at least one antioxidant, thermal stabilizer and / or acid scavenger, preferably in a total amount of < 3000 ppm, based on the entire multilayer film.

[0098] Preferably, the polymer layers (A), (B), and (C) adhere to one another without the use of an adhesion promoter; that is, the multilayer film according to the invention, consisting of polymer layers (A), (B), and (C), preferably contains no adhesion promoter. Furthermore, preferably at least the second polymer layer (B) contains no further additives and / or processing aids (e.g., modifiers or plasticizers, such as mineral oil), and most preferably, none of the polymer layers (A), (B), and (C) contains any further additives and / or processing aids in addition to the additives mentioned above. Accordingly, the multilayer film according to the invention, used as packaging, has no or hardly any effect on the drug or medical solution during sterilization and storage.

[0099] In the case of a multilayer film according to the invention consisting of the polymer layers (A), (B), (C) and the functional layer (D), the multilayer film generally contains, in addition to the additives mentioned above as preferred, an adhesion promoter or adhesive.

[0100] The thickness of the first polymer layer (A) is generally 5 to 15 wt.%, preferably 7 to 13 wt.%, particularly preferably 7.5 to 10 wt.%, of the total film thickness of the multilayer film according to the invention.

[0101] The thickness of the second polymer layer (B) is generally 5 to 15 wt.%, preferably 7 to 13 wt.%, particularly preferably 7.5 to 10 wt.%, of the total film thickness of the multilayer film according to the invention.

[0102] The middle polymer layer (C) has the largest proportion (preferably at least 70 wt.% of the total film thickness) of the multilayer film according to the invention and serves to improve the impact strength of the entire structure.

[0103] If present, the thickness of the optional functional layer (D) is preferably 2.5 to 12.5 wt.%, particularly preferably 5 to 10 wt.%, of the total film thickness of the multilayer film according to the invention.

[0104] The total film thickness of the multilayer film according to the invention is preferably 50 to 500 µm, particularly preferably 100 to 400 µm, and most preferably 150 to 300 µm.

[0105] The total film thickness of a multilayer film according to the invention, consisting of the polymer layers (A), (B) and (C), is preferably 50 to 500 µm, particularly preferably 100 to 400 µm, and most preferably 150 to 300 µm.

[0106] A multilayer film according to the invention is particularly preferred, consisting of the polymer layers (A), (B) and (C), and characterized in that the total film thickness of the multilayer film is 50 to 500 µm, particularly preferably 100 to 400 µm, and - in each case based on the total film thickness of the multilayer film the thickness of the first polymer layer (A) is 5 to 15 wt.%, preferably 7 to 13 wt.%, the thickness of the second polymer layer (B) is 5 to 15 wt.%, preferably 7 to 13 wt.%; and the thickness of the middle polymer layer (C) is 70 to 85 wt.%, preferably 74 to 80 wt.%; and the proportions of (A), (B) and (C) together each amount to 100 wt.%. Method for producing the multilayer film

[0107] Another object of the invention is a method for producing the multilayer film according to the invention, wherein the first polymer layer (A), the middle polymer layer (C), and the second polymer layer (B) are coextruded.

[0108] In coextrusion, the polymer melts of the polymer layers (A), (B) and (C) are combined to form the multilayer film according to the invention before leaving the profile die of an extruder.

[0109] The extrusion process is often a two-stage process. In a first step, the materials used for the individual polymer layers are mixed and compacted in extruders, preferably parallel twin-screw extruders (compounders), heating / cooling mixers, or pelletizing presses. Then, the polymer melts of the polymer layers (A), (B), and (C) are combined in another, directly coupled or spatially and temporally separated extruder before exiting the profile die to form the multilayer film according to the invention.

[0110] Preferably, the multilayer film obtained by the inventive method is shock-cooled with water.

[0111] By coextrusion, the multilayer film according to the invention can be obtained in the form of a flat film (flat film process, e.g. when using a slot die) or a film tube (blown film process, e.g. flooding the interior of the film tube with - preferably sterile filtered - air), wherein in the case of a film tube the outside consists of the first polymer layer (A) and the inside of the second polymer layer (B).

[0112] In a further process step, the optional functional layer (D) can be applied to the multilayer film obtained by the inventive process - e.g. by hot lamination or preferably by laminating.

[0113] According to a particular embodiment for the production of a laminated multilayer film tube according to the invention, the inventive method comprises the following steps: (a`) Producing a film tube from the multilayer film according to the invention by coextrusion of the first polymer layer (A), the middle polymer layer (C), and the second polymer layer (B), wherein the interior of the film tube is flooded with air – preferably sterile filtered; (b') optionally cooling the film tube produced in process step (a'); (c') coating the optionally cooled film tube with an adhesive layer on at least one side (first polymer layer (A)) of the film tube; (d') optionally drying the film tube provided with the adhesive layer; (e') laminating the at least one side coated with the adhesive layer (first polymer layer (A)) of the film tube with a functional layer (D), in particular a SiOx / PET functional layer; (f) optionally drying or curing the laminated film tube.

[0114] According to the inventive method of the aforementioned embodiment, the two parallel inner sides (second polymer layers (B)) of the film tube preferably adhere directly to each other after the melt or co-extrusion of the film tube, so that a coating of the outer sides (first polymer layers (A)) of the film tube is possible with a closed interior of the film tube. The closed interior, which is inflated during subsequent use of the resulting film tube, is thus essentially particle-free.

[0115] Preferably, in the inventive method of the aforementioned embodiment, the interior of the film tube is flooded with sterile filtered air, so that a particle-free, laminated multilayer film tube is obtained which is particularly suitable for medical purposes.

[0116] The aforementioned process according to the invention is particularly preferably carried out in a cleanroom for the production of a particle-free, laminated multilayer film tube.

[0117] In the inventive method according to the above embodiment, an adhesion promoter is preferably used which enables complete curing at room temperature after approximately 2 weeks, preferably 1 week. In a heat chamber, curing can also occur more quickly at elevated temperatures, preferably 30°C or more, often 40°C to 60°C.

[0118] Suitable adhesion promoters (adhesives, bonding adhesives or laminating adhesives) include, for example, isocyanates, polyurethanes, poly(ethyl acrylate / methacrylic acid ester), pure acrylate copolymers, vinyl ester / acrylate copolymers or inorganic-organic hybrid polymers.

[0119] Preferred adhesion promoters are two-component systems that can be solvent-based or solvent-free, and silane-based or silane-free, and can optionally be used with an additional "catalyst" to accelerate curing.

[0120] Suitable solvent-based two-component systems include, for example, polyurethane adhesives and other commercially available systems such as... Dow ADCOTE ™< 675A + ADCOTE ™< 675C coreactant; Dow ADCOTE 811A + ADCOTE 811B coreactant; Dow ADCOTE E735A-75 + ADCOTE ™< E735C2 coreactant: MORCHEM PS 241 AE + CS-97 coreactant, Henkel Loctite Liofol LA2798 + Henkel Loctite Liofol LA7371; Henkel LOCTITE HY 4070 2K hybrid adhesive.

[0121] The aforementioned systems can optionally be used with "catalysts," including those such as Dow. Catalyst 9L10 (polyisocyanate), Dow Catalyst 9L200 and Dow Catalyst F Adcote 40-3E, which are commercially available.

[0122] Suitable solvent-free two-component systems include, for example, polyurethane adhesives and other commercially available systems such as... Dow MOR-FREE ™< L 75-720 Adhesive + CR 88-720 or CR 88-721 or MOR-FREE ™< C 79 S coreactant Dow MOR-FREE ™< 203A Adhesive + MOR-FREE ™< 200C coreactant Dow MOR-FREE ™< L705 Adhesive + MOR-FREE ™< C 79 or MOR-FREE ™< C-102 coreactant.

[0123] Alternatively, single-component systems can also be used as adhesion promoters, which can be solvent-based or solvent-free, and silane-containing or silane-free, and can optionally be used with an additional "catalyst" to accelerate curing.

[0124] Suitable solvent-free, one-component systems include, for example, Dow MOR-FREE ™< ELM 415A (polyurethane adhesive) or SENOBOND ®< -WB film laminating adhesive FP NDC 375224, which are commercially available.

[0125] The adhesive is particularly preferably selected to meet the requirements of Pharmacopoeia Limits, for example with regard to migration properties, and is preferably free of organic solvents.

[0126] Depending on the process or desired coating, the adhesive layer can be applied to one or both sides of the co-extruded film tube. This can be done, for example, by spraying or applying with a doctor blade. The use of aqueous solutions of the appropriate adhesives is also suitable.

[0127] After applying these adhesive layers, the resulting foil tube can be dried if necessary. For example, if the adhesive is applied using water, drying can be achieved by evaporating the water.

[0128] The thickness of the adhesive layers is preferably in the range of 3 to 10 µm.

[0129] The invention also relates to the use of the multilayer film according to the invention for the production of medical packaging, preferably a medical bag.

[0130] The invention also relates to the use of the medical packaging according to the invention, preferably as a container for at least one drug.

[0131] The medical packaging according to the invention is particularly suitable as a container for at least one drug, wherein, due to the combination of a

[0132] Polypropylene-based outer and middle layers (polymer layers (A) and (C)) with a polyethylene-based inner layer (polymer layer (B)) ensure very good processability on all common bag sealing machines and at the same time the polyethylene of the inner layer has a particularly low tendency to adsorb medical active ingredients.

[0133] In a preferred embodiment, the packaging according to the invention is divided into chambers so that it can be used as a container for several medications simultaneously. This is relevant, for example, for drug combinations that must be administered together but are not stable in combination over extended periods, or for solid medications that are administered as a solution or suspension but are not stable in solution or suspension over extended periods. Separate chambers allow the components of the final dosage form to be stored separately and mixed together shortly before administration by opening the dividing lines.

[0134] A method for manufacturing a medical packaging according to the invention, preferably a pouch, comprises the following steps: a) Providing at least one heat-sterilizable multilayer film according to the invention; b) optionally providing one or more port elements and / or tubes; c) forming a medical package, preferably a pouch, from the at least one heat-sterilizable multilayer film, such that the second polymer layer (B) forms the inner surface of the medical package, preferably the pouch, and the first polymer layer (A) forms the outer surface of the medical package, preferably the pouch; d) optionally positioning the port elements and / or tubes between the inner surfaces on the contours of the medical package, preferably the pouch; e) bringing the inner surfaces on the contours of the medical package, preferably the pouch, into contact with each other and with port elements and / or tubes optionally positioned between them;f) Welding the inner surfaces along the contours of the medical packaging, preferably the pouch, together and with any port elements and / or tubing positioned between them.

[0135] In step a), the multilayer film according to the invention is preferably provided in the form of a flat film or a tubular film. Depending on the form of the film provided, the further process may differ in certain details. The resulting low-particle film tube can be laminated with a functional layer (D), e.g., a SiOx / PET functional layer, by additional process steps.

[0136] Depending on the application of the medical packaging according to the invention, preferably the pouch, additional elements, such as port elements and / or tubing, can optionally be provided in step b) of the process after the provision of the multilayer film according to the invention. Providing these elements is advantageous, for example, if the medical packaging according to the invention, preferably the pouch, is to be used as an integral part of a medical device or is to be connected to a medical device. Omitting step b) may be advantageous, for example, if the medical packaging, preferably the pouch, serves only to store a medication and is damaged for medication removal, for example, by tearing or puncturing with a cannula.

[0137] In step c), the multilayer film provided according to the invention is formed into the shape of a medical package, preferably a pouch. If a tubular film was provided in step a), forming the medical package, preferably the pouch, can, for example, simply involve cutting the tubular film to the desired length, since the second polymer layer (B) already forms the inner surface of the tubular film and the first polymer layer (A) forms the outer surface. If a flat film was provided in step a), the medical package, preferably the pouch, can be formed in step c), for example, from a single piece of multilayer film by cutting this piece into a mirror-symmetrical shape and folding it over along the axis of symmetry so that the edges of the film are congruent, with the second polymer layer (B) on the inside.Alternatively, the medical packaging according to the invention, preferably the pouch, can be formed, for example, from two pieces of flat film by cutting the two pieces mirror-symmetrically to each other and placing them congruently on top of each other, with the second polymer layer (B) on the inside. Rectangular shapes are particularly preferred for cutting, as this minimizes material waste and simplifies processing. However, other shapes are also possible, so that, for example, medical packaging, preferably a pouch, can be produced with an aesthetically pleasing shape that is appealing to children and distracts them from the actual administration of medication.

[0138] Depending on whether additional elements such as port elements and / or tubing were provided in step b), these elements can be positioned in step d) between the inner surfaces along the contours of the shaped medical packaging, preferably the pouch. In the case of a tubular film, this means inserting the additional elements into the openings of the tubular film. The elements can only be positioned on two opposite sides of the medical packaging, preferably the pouch. In the case of a flat film, this means inserting the additional elements between the edges of one or more flat film pieces that were aligned in step c). The elements can be positioned at any point along the edges, preferably at most on two opposite edges.

[0139] In step e), the inner surfaces of the shaped medical packaging, preferably the pouch, are brought into contact with each other and with any additional elements located between the inner surfaces along its contours, so that they can be welded together in step f) by applying heat and, if necessary, mechanical pressure. During welding, the temperature is preferably selected such that it is above the melting or softening point of the second polymer layer (B), but below the melting or softening point of the first polymer layer (A). This ensures that the second polymer layer (B) melts along the contours of the medical packaging, preferably the pouch, thereby sealing it tightly and fluid-tight, while the first polymer layer (A) retains its shape and thus maintains the stability of the medical packaging, preferably the pouch.

[0140] An important criterion for using the multilayer film according to the invention as primary packaging for medical solutions is its barrier effect against liquid loss. Such liquid loss leads to an increase in the concentration of the solution's active ingredients, which must not exceed certain values. Liquid loss during storage, among other things, determines the product's shelf life. The formulation of the multilayer film according to the invention is selected to achieve a very good water vapor barrier while maintaining good impact strength.

[0141] The multilayer film according to the invention is characterized by the fact that it is heat-sterilizable, impact-resistant and flexible (without plasticizers) and can be reliably welded to port elements using a thermally heated welding process, and that it also has good adhesion between the individual layers and does not require an adhesion promoter and medical solutions or drugs are not affected or at least hardly affected.

[0142] Multilayer films according to the invention, provided with an additional functional layer (D), in particular a SiOx / PET functional layer, exhibit a significantly improved gas barrier, which also allows the storage of oxygen-sensitive ingredients.

[0143] The invention will be explained in more detail below using examples, without thereby limiting it. Example 1:

[0144] First polymer layer (A): 97 wt% Moplen® < HP525J from LyondellBasell Corp., USA / Propylene homopolymer 3 wt% Tuftec® < H1062 from Asahi Kasei, Japan / Styrene-ethylene / butylene block copolymer

[0145] The aforementioned formulation was homogeneously mixed in a separate compounding step in the molten state, extruded, and granulated for further use. Second polymer layer (B):

[0146] B1) 75 wt% Tosoh FY-13 from Tosoh Corp., Japan / / Composite of ethylene homopolymer (70 to 80 wt%) and ethylene-1-butene copolymer (20 to 30 wt%) / Density: 950 kg / m³, Tm: 128°C B2) 20 wt% Bormed® < TD109CF from Borealis, Austria / Propylene terpolymer B3) 5 wt% Engage® < 8003 from Dow Chemical Company, USA / Ethylene-octene polyolefin elastomer

[0147] The aforementioned formulation was homogeneously mixed in a separate compounding step in the molten state, extruded, and granulated for further use.

[0148] Middle polymer layer (C): C1) 70 wt% Bormed® < TD109CF from Borealis, Austria / Propylene terpolymer C2) 20 wt% Tuftec® < H1062 from Asahi Kasei, Japan / Styrene-ethylene / butylene block copolymer C3) 10 wt% Engage® < 8003 from Dow Chemical Company, USA / Ethylene-octene polyolefin elastomer

[0149] The aforementioned formulation was homogeneously mixed in a separate compounding step in the molten state, extruded, and granulated for further use.

[0150] The melts from the granulated compounds of the first polymer layer (A), the middle polymer layer (C) and the second polymer layer (B) were co-extruded on a water-cooled blown film line using process parameters typical for polypropylene, resulting in a multi-layer film in the form of a film tube whose interior was flooded with sterile filtered air.

[0151] The film was manufactured with a total thickness of 200 µm, with the first polymer layer (A) and second polymer layer (B) each having a thickness of 15 µm and the middle polymer layer (C) having a thickness of 170 µm.

[0152] The manufactured film can be sterilized with hot steam and can be firmly welded using welding tools heated to 125°C. Example 2:

[0153] A foil tube produced according to Example 1 was additionally provided on both sides with a functional layer (D) made of SiOx / PET (Techbarrier T from Mitsubishi) with a layer thickness of 15 µm each.

[0154] First, a two-component adhesive (Dow ADCOTE 811A + ADCOTE 811B coreactant, and Dow Catalyst 9L10, available from Dow Chemical) was applied to both sides of the flattened foil tube, and then the adhesive-coated foil tube was laminated on both sides with the functional layer.

[0155] The manufactured film can be sterilized with hot steam and can be firmly welded using welding tools heated to 125°C. Example 3 (comparative example according to DE 10361851 A1, Example 1) First polymer layer (A):

[0156] 97 wt% Moplen® < HP525J from LyondellBasell Corp., USA / Polypropylene homopolymer 3 wt% Tuftec® < H1062 from Asahi Kasei, Japan / Styrene-ethylene / butylene block copolymer

[0157] The aforementioned formulation was mixed in a separate compounding step in the molten state and granulated for further use. Second polymer layer (B):

[0158] 85 wt% Bormed® < TD109CF from Borealis, Austria / Propylene terpolymer 15 wt% Tuftec® < H1062 from Asahi Kasei, Japan / Styrene-ethylene / butylene block copolymer

[0159] The aforementioned formulation was mixed in a separate compounding step in the molten state and granulated for further use. Middle polymer layer (C):

[0160] 75 wt% Bormed® < TD109CF from Borealis, Austria / Propylene terpolymer; 20 wt% Tuftec® < H1062 from Asahi Kasei, Japan / Styrene-ethylene / butylene block copolymer; 5 wt% Engage® < 8003, Dow Chemical Company, USA / Ethylene-octene polyolefin elastomer

[0161] The aforementioned formulation was mixed in a separate compounding step in the molten state and granulated for further use.

[0162] The film was co-extruded on a water-cooled blown film line using process parameters typical for polypropylene.

[0163] The film was manufactured with a total thickness of 200 µm, with the first polymer layer (A) and second polymer layer (B) each having a thickness of 15 µm and the middle polymer layer (C) having a thickness of 170 µm. The manufactured film is steam sterilizable and can be welded securely using welding tools heated to 125°C. Example 4 (not according to the invention, comparison) First polymer layer (A):

[0164] 97 wt% Moplen® < HP525J from LyondellBasell Corp., USA / Polypropylene homopolymer 3 wt% Tuftec® < H1062 from Asahi Kasei, Japan / Styrene-ethylene / butylene block copolymer

[0165] The aforementioned formulation was homogeneously mixed in a separate compounding step in the molten state, extruded, and granulated for further use. Second polymer layer (B):

[0166] 75 wt% Bormed® < LE6600-PH from Borealis, Austria / low-density polyethylene (LDPE) 20 wt% Bormed® < TD109CF from Borealis, Austria / propylene terpolymer 5 wt% Engage® < 8003 from Dow Chemical Company, USA / ethylene-octene polyolefin elastomer

[0167] The aforementioned formulation was homogeneously mixed in a separate compounding step in the molten state, extruded, and granulated for further use. Middle polymer layer (C):

[0168] 70 wt% Bormed® < TD109CF from Borealis, Austria / Propylene terpolymer; 20 wt% Tuftec® < H1062 from Asahi Kasei, Japan / Styrene-ethylene / butylene block copolymer; 10 wt% Engage® < 8003, Dow Chemical Company, USA / Ethylene-octene polyolefin elastomer

[0169] The aforementioned formulation was homogeneously mixed in a separate compounding step in the molten state, extruded, and granulated for further use.

[0170] The granulated compounds of the polymer layers (A), (B) and (C) were co-extruded on a water-cooled blown film machine using process parameters typical for polypropylene, and a multi-layer film in the form of a film tube was obtained.

[0171] The film was manufactured with a total thickness of 200 µm, with the first polymer layer (A) and second polymer layer (B) each having a thickness of 15 µm and the middle polymer layer (C) having a thickness of 170 µm. Investigation of the weld strength (SNF) of films of examples 1 to 4

[0172] 1. (a) Preparation of sealed samples using a foil sealing machine (IST Med by Kopp) from two overlapping foils (each 20 x 15 cm); sealing area (foil edge) -15 mm. Sealing parameters: pressure: 2-3 bar, time: 1-2 seconds, gap: 320 µm. (b) Subsequently, punching out 15 x 80 mm wide sample strips with sealed edges (= unsterilized samples). 2. Steam sterilization at 121 °C (Webeco Type A 35 autoclave, 2 bar, 20 minutes) of some of the resulting sample strips with sealed edges (= steam sterilized samples). To prevent the foil from clogging, the unsealed areas of the sample strips are opened beforehand and paper is inserted between them. 3. Determination of the weld strength by clamping the cooled test strips with welded edges into a tensile testing machine (Zwick iLine 500N from Zwick) and pulling the test strips at a rate of 400 mm / min.

[0173] The results for evaluating the weld are given in N / 15mm.

[0174] The weld strength of the multilayer film should be greater than 25 N / 15 mm, preferably greater than 30 N / 15 mm. If the weld strength of the multilayer film is 10 to 20 N / 15 mm, it is a peel weld.

[0175] Figure 1 shows welding curves of unsterilized samples according to examples 1 to 4. The x-axis indicates the welding temperature [°C]; the y-axis the tensile strength [N / 15mm].

[0176] Figure 2 shows welding curves of hot steam sterilized samples according to examples 1 to 4. The x-axis indicates the welding temperature [°C]; the y-axis the tensile strength [N / 15mm].

[0177] In the figures, the individual examples are characterized by different line structures. Results: (a) Unsterilized samples

[0178] The welding curves (see Figure 1The films of examples 1, 3 and 4 exhibit a SNF of >30N / 15mm at approximately 130°C; the film of example 2 with the PET / SiOX functional layer begins to weld at approximately 5°C higher (SNF >30N / 15mm), which is not a problem due to the higher temperature resistance of the film caused by the PET / SiOX functional layer. (b) Steam-sterilised samples

[0179] The welding curves (see Figure 2 The films in Examples 1, 2, and 3 are similar to those of the unsterilized samples, i.e., they exhibit a SNF of >30 N / 15 mm at approximately 130°C and 135°C, respectively. The film in Example 4 (second polymer layer based on LDPE) does not show the desired weld strength after steam sterilization. The weld seam separates, peels, or delaminates. If films according to Example 4 were used as medical pouches, the pouches would open during sterilization in the autoclave or upon removal.

[0180] PE materials such as LDPE or HDPE are not compatible with polypropylene; that is, in the case of multilayer films with PP-based middle layers, the inner layer easily separates from the middle layer. Furthermore, the melting point of LDPE raw materials is 110 to 115°C, meaning the raw material melts during steam sterilization and weakens the weld.

[0181] It is shown that the multilayer film according to the invention according to Examples 1 and 2, due to the specific combination of a polyethylene-based composite B1), a PP terpolymer B2) and a polyethylene elastomer B3) (as an adhesion promoter) used for the second polymer layer (inner layer) B), has the advantage that the inner layer B) cannot be easily detached from the middle layer C), furthermore the composite B1) used does not melt during steam sterilization and thus the weld strength remains sufficiently high.

[0182] Compared to the prior art multilayer films according to Example 3 (inner layer B made of impact-modified propylene terpolymer), the multilayer films of Examples 1 and 2 according to the invention exhibit very good impact strength even without the addition of an impact modifier – due to the polyethylene-based composite B1) used for the inner layer B) – and have comparable weld strength and suitability for steam sterilization. Furthermore, the multilayer films according to the invention offer the advantage over those according to Example 3 that active ingredients adhere less strongly to the PE-containing inner layer, i.e., the so-called "recovery value" is higher.

Claims

1. Heat-sterilizable multilayer film comprising a) a first polymer layer (A) containing at least one propylene homopolymer modified with at least one impact modifier; b) a second polymer layer (B) containing: B1) 60% to 85% by weight - based on (B) - of a homogeneous composition (B1) consisting of: B11) 65% to 85% by weight - based on (B1) - of ethylene homopolymer, and B12) 15% to 35% by weight, preferably 20% to 30% by weight - based on (B1) - of at least one ethylene copolymer which contains as comonomer at least one alpha-olefin having 4 to 12 carbon atoms, where (B1) has a melting temperature of > 125°C, determined as specified in the description, and a density, determined according to DIN EN ISO 1183-1 : 2019-09 - Method B, of 945 to 960 kg / m3; B2) 11% to 30% by weight - based on (B) - of at least one propylene terpolymer; B3) 4% to 15% by weight - based on (B) - of at least one polyethylene elastomer which is a copolymer of ethylene with at least one alpha-olefin having 4 to 12 carbon atoms; c) a central polymer layer (C) situated between the first polymer layer (A) and the second polymer layer (B), containing: C1) 61% to 80% by weight - based on (C) - of at least one propylene terpolymer; C2) 15% to 25% by weight - based on (C) - of at least one styrene block copolymer elastomer; C3) 5% to 19% by weight - based on (C) - of at least one polyethylene elastomer which is a copolymer of ethylene with at least one alpha-olefin containing 4 to 12 carbon atoms.

2. Heat-sterilizable multilayer film according to claim 1, characterized in that the homogeneous composition B1) consists of: B11) 70% to 80% by weight, and B12) 20% to 30% by weight.

3. Heat-sterilizable multilayer film according to claim 1 or 2, characterized in that the ethylene copolymer B12) is prepared by copolymerization of ethylene and at least one alpha-olefin in the presence of a metallocene catalyst.

4. Heat-sterilizable multilayer film according to any of claims 1 to 3, in which the ethylene homopolymer B11) used is a high-density polyethylene (HDPE), preferably an HDPE having a density of 950 to 970 kg / m3.

5. Heat-sterilizable multilayer film according to any of claims 1 to 4, characterized in that the ethylene copolymer B12) contains 25% to 40% by weight, preferably 30% to 37% by weight, of at least one alpha-olefin comonomer.

6. Heat-sterilizable multilayer film according to any of claims 1 to 5, characterized in that the ethylene copolymer B12) contains as comonomer at least one alpha-olefin selected from 1-butene, 1-pentene, 1-hexene and 4-methyl-1-pentene, preferably 1-butene.

7. Heat-sterilizable multilayer film according to any of claims 1 to 6, in which component B2) and / or C1) is a terpolymer of propylene, ethylene and / or C4 to C16 α-olefins, preferably a terpolymer of propylene, ethylene and butylene.

8. Heat-sterilizable multilayer film according to any of claims 1 to 7, in which component B3) is a copolymer of ethylene with an alpha-olefin having 7 to 12 carbon atoms.

9. Heat-sterilizable multilayer film according to any of claims 1 to 8, in which the second polymer layer (B) contains: B1) 65% to 80% by weight, preferably 72% to 78% by weight, B2) 15% to 25% by weight, preferably 17% to 22% by weight; B3) 4% to 12% by weight, preferably 5% to 10% by weight.

10. Heat-sterilizable multilayer film according to any of claims 1 to 9, in which the central polymer layer (C) contains: C1) 65% to 75% by weight; C2) 17% to 22% by weight; C3) 8% to 17% by weight.

11. Heat-sterilizable multilayer film according to any of claims 1 to 10, in which the styrene block copolymer (SBC) elastomer C2) is selected from the group consisting of: styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPS), styrene-isoprene-styrene block copolymer (SIS) and styrene-butadiene-styrene block copolymer (SBS), preferably SEBS and SEPS, in particular SEBS.

12. Heat-sterilizable multilayer film according to any of claims 1 to 11, in which the polyethylene elastomer C3) is an ethylene-butylene copolymer and / or an ethylene-octene copolymer, in particular an ethylene-octene copolymer.

13. Heat-sterilizable multilayer film according to any of claims 1 to 12, characterized in that the multilayer film consists of the polymer layers (A), (B) and (C), and the total film thickness of the multilayer film is 50 to 500 µm, preferably 100 to 400 µm, and - based in each case on the total film thickness of the multilayer film - the layer thickness of the first polymer layer (A) is 5% to 15% by weight, preferably 7% to 13% by weight; the layer thickness of the second polymer layer (B) is 5% to 15% by weight, preferably 7% to 13% by weight; and the layer thickness of the central polymer layer (C) is 70% to 90% by weight, preferably 74% to 86% by weight.

14. Method for producing a heat-sterilizable multilayer film according to any of claims 1 to 13, wherein the first polymer layer (A), the central polymer layer (C) and the second polymer layer (B) are coextruded.

15. Heat-sterilizable multilayer film according to any of claims 1 to 12, which comprises an additional functional layer (D) adjacent to the first polymer layer (A) on the outer side of (A) and wherein functional layer (D) contains at least one material selected from the group consisting of: ethylene-vinyl alcohol copolymers, polyvinyl alcohols, polyamides, liquid crystal polymers (LCP), aromatic polyesters, preferably terephthalic acid polyesters, particularly preferably polyethylene terephthalates (PET), silicon oxide (SiOx), aluminum oxide (AlOx) and acrylate-based polymers.

16. Heat-sterilizable multilayer film according to claim 15, in which functional layer (D) consists of PET / SiOx.

17. Method for producing a laminated multilayer film sleeve made of a heat-sterilizable multilayer film according to any of claims 15 or 16, comprising the following steps: (a`) producing a film sleeve made of a multilayer film produced according to claim 14, wherein the interior of the film sleeve is flooded with - preferably sterile-filtered - air; (b') optionally cooling the film sleeve produced in method step (a'); (c') coating the optionally cooled film sleeve with a pressure-sensitive adhesive layer on at least one side (first polymer layer (A)) of the film sleeve; (d') optionally drying the film sleeve provided with the pressure-sensitive adhesive layer; (e') laminating the at least one side (first polymer layer (A)) of the film sleeve coated with the pressure-sensitive adhesive layer with a functional layer (D), in particular a SiOx / PET functional layer; (f) optionally drying or curing the laminated film sleeve.

18. Use of a heat-sterilizable multilayer film according to any of claims 1 to 13, 15 or 16 for production of a medical package, preferably a medical bag.

19. Method for producing a medical package, preferably a bag, made of a heat-sterilizable multilayer film according to any of claims 1 to 13, 15 or 16, comprising the steps of: a) providing at least one multilayer film produced according to claim 14 or 17; b) optionally providing one or more port elements and / or flexible tubes; c) shaping a medical package, preferably a bag, from the at least one multilayer film, such that the second polymer layer (B) forms the inner face of the medical package, preferably the bag, and the first polymer layer (A) forms the outer face of the medical package, preferably the bag; d) optionally positioning the port elements and / or flexible tubes between the inner faces at the contours of the medical package, preferably the bag; e) contacting the inner faces at the contours of the medical package, preferably the bag, with one another and with port elements and / or flexible tubes optionally positioned in between; f) heat-sealing the inner faces at the contours of the medical package, preferably the bag, with one another and with port elements and / or flexible tubes optionally positioned in between.