HK40103430B

HK40103430B - Flexible heat‑sterilizable non‑pvc multilayer film for medical packaging

Info

Publication number: HK40103430B
Application number: HK62024091531.9A
Authority: HK
Inventors: S·霍尔策; R·格罗斯
Original assignee: 玻利西尼有限公司
Priority date: 2021-03-09
Filing date: 2022-03-07
Publication date: 2025-05-23

Description

The invention relates to heat-sterilizable multi-layer films containing aliphatic polyolefins, a method for their production, and their use in the production of medical packaging, as well as medical packaging containing such multi-layer films. The multi-layer films are steam-heat sterilizable and, when used for medical packaging, exhibit a low tendency to adsorb medications or medical solutions, a temperature-resistant outer layer, and sufficient adhesion between the individual layers.

Multilayer films have found a wide range of applications for many years, for example in the food industry, but also in the medical/pharmaceutical field, such as secondary packaging (secondary packaging) or primary packaging for solution bags, dry concentrates, and medicines in tablet form.

Some multilayer films are suitable for flexible packaging, which can be used, for example, as bags for packaging and administering medical solutions. As a common practice, medical solutions such as infusion solutions for parenteral administration are currently available on the market in flexible single-use bags made of polyvinyl chloride (PVC) or non-PVC materials.

Elastic PVC materials are a health concern because they contain plasticizers that can be released again. Therefore, efforts are being made to replace PVC with non-PVC materials.

Flexible medical bags must not only have the ability to collapse, ensuring complete drainage of the bag, but also meet additional performance criteria such as transparency, heat sterilizability at 121°C, sufficient mechanical strength especially under dynamic loading in the weld area, good water vapor barrier properties, capability to withstand typical pressure cuff applications such as pressure infusions, and from a pharmaceutical perspective, they should have minimal influence on the contents of the bag due to the packaging.

Multi-layer films with a layer structure based on polyolefins have proven to be advantageous regarding these requirements.

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

DE 203 20 212 A1 describes a heat-sterilizable three-layer multilayer film produced by co-extrusion for use in medical bags. Representative films have an outer layer consisting of 97 wt.% polypropylene homopolymer and 3 wt.% SEBS block copolymer, a middle layer composed of 80 wt.% EXCELLEN—a heterogeneous copolymer based on polypropylene and polyethylene—and 20 wt.% SEBS block copolymer, and an inner layer comprising 75 wt.% PP terpolymer, 20 wt.% SEBS block copolymer, and 5 wt.% PE plastomer.

KR-A 2010-0101332 discloses multi-layer films with excellent adhesion between the layers, produced by co-extrusion of a polypropylene layer and an ethylene layer, wherein the polypropylene layer is a blend with ethylene (content 40 to 50 wt.-%) or the ethylene layer is a blend with polypropylene (content 20 to 50 wt.-%).

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

EP-A 0229475 describes a multi-layer film for medical containers, preferably a three-layer film, comprising (a) a first (= inner) heat-sealable layer made of a blend, preferably containing 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 made of a blend of (i) polyethylene (HDPE) (50 to 90 wt.%) and (ii) a modifier; and (c) a third (outer) layer made of a blend of (i) polypropylene and (ii) a modifier.

JP-A 2007/245490 describes a heat-sterilizable multi-layer film for use in medical bags, which comprises an inner layer of high density (0.89 to 0.93 g/cm³) made from a blend of an ethylene/α-olefin copolymer (produced using a metallocene catalyst) and HDPE (content 10 to 40 wt.%), and an outer layer made from a polypropylene polymer.

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

Multilayer films according to the prior art are still in need of improvement, particularly with regard to the adhesion between the individual layers and the requirements for sterilizability with hot steam at 121°C.

The object of the present invention is therefore to provide a flexible, heat-sterilizable multi-layer film for medical purposes, which exhibits good adhesion between the individual layers and good impact resistance, and further has a low tendency to adsorb medications or medical solutions on the surface facing the medication or medical solution (inner layer), and can be processed into medical containers (e.g., bags) by simple methods.

A subject of the invention is a heat-sterilizable multilayer film comprising: a) a first polymer layer (A) containing at least one, preferably one, impact modifier-modified polypropylene homopolymer; b) a second polymer layer (B) containing: B1) 60 to 85 wt.% - based on (B) - of a homogeneous composition (= "Composite") (B1) consisting of: B11) 65 to 85 wt.% - based on (B1) - of an ethylene homopolymer, and B12) 15 to 35 wt.%, preferably 20 to 30 wt.%, - based on (B1) - of at least one ethylene copolymer, which contains as 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 temperature of > 125°C and a density of 945 to 960 kg/m3; B2) 11 to 30 wt.-% based on (B) of at least one propylene terpolymer; B3) 4 to 15 wt.-% based on (B) of 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.

The proportions given in weight percent (wt.-%) add up to 100 wt.-% respectively.

In the sense of the present invention, the structural units of a monomer in a (co)polymer are understood to be the structural units derived from the monomer that has been homopolymerized.

The term "heat-sterilizable" means that the corresponding materials can undergo sterilization at elevated temperatures, preferably through steam sterilization. Sterilization refers to processes by which materials and objects are freed from living microorganisms. The condition achieved in this way is referred to as "sterile." In the case of steam sterilization of filled or unfilled medical packaging, hot steam is used for sterilization, which is typically carried out in an autoclave. During this process, the medical packaging is preferably heated for 20 minutes to 121°C at 2 bar pressure using steam. The air inside the autoclave is completely replaced by steam.

The term "multilayer film" refers to thermoplastic materials consisting of several co-extruded polymer layers that are connected together to form a film in the form of a continuous sheet or tube.

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

The term "impact toughness" refers to the property of a material to resist dynamic loading. According to the standard DIN EN ISO 180:2013-08, the Izod impact toughness of plastics can be measured under defined conditions.

Under a "homogeneous composition," a composite made of substances (components) mixed at the molecular level is meant, which together form a single phase.

The "melting temperature" (softening temperature, Tm) is usually determined by DSC (Differential Scanning Calorimetry).

The "density" can be determined according to DIN EN ISO 1183-1 (2019-09) - Method B) using the liquid pycnometer.

First polymer layer (A)

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

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

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.

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

The first polymer layer (A) contains (or consists of) at least one, preferably one, polypropylene homopolymer (polypropylene), which is generally modified with 1 to 30 wt.%, preferably 2 to 20 wt.%, particularly preferably 2 to 10 wt.%, especially 3 to 5 wt.% of at least one impact modifier in order to improve the (low temperature) impact strength.

The production of polypropylene homopolymers is known. Furthermore, polypropylene homopolymers are commercially available, for example from LyondellBasell Corporation, USA.

Preferably, the first polymer layer (A) contains (or consists of) a polypropylene homopolymer modified with at least one impact modifier, selected from the group of styrene block copolymers such as, for example, 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, particularly SEBS, and/or from the group of ethylene copolymers with at least one alpha-olefin containing 4 to 12, preferably 4 to 8 carbon atoms, such as ethylene-butylene copolymers and/or ethylene-1-octene copolymers.

In particular, the first polymer layer (A) contains (or consists of) 90 to 98% by weight, preferably 95 to 97% by weight, of a polypropylene homopolymer and 2 to 10% by weight, preferably 3 to 5% by weight, 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.

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

The weight values for the components of the first polymer layer (A) refer to the total weight of the first polymer layer (A).

Second polymer layer (B)

The second polymer layer (B) is defined as the polymer layer that, during processing of the multilayer film according to the invention, is located on the inside of the packaging, which preferably is a bag. This polymer layer is responsible for allowing the packaging to be sealed by welding. The second polymer layer (B) of the film must be weldable to itself and to the inserted port elements in a safe manner, at as low a temperature and welding time as possible, yet still capable of being heat-sterilized at temperatures above 121°C. A low welding temperature is particularly important to minimize the stress placed on the film structure by internal stresses. Therefore, the melting or softening temperature of the second polymer layer (B) is generally above 121°C, preferably between 122°C and 135°C, particularly preferably between 124°C and 130°C, but in any case below the melting or softening temperature of the first polymer layer (A).

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 amounts (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)

Component B1 is used to reduce the tendency for delamination between the second polymer layer (B) and the middle polymer layer (C).

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

The homogeneous composition (B1) has a melting temperature of > 125°C, preferably from 130 to 135°C, and a density of 945 to 960 kg/m³.

The ethylene copolymer B12 contains, in addition to the alpha-olefin with 4 to 12 carbon atoms, no other comonomers.

The content of the alpha-olefin comonomer—based on (B12)—is generally 25 to 40 wt.%, preferably 30 to 37 wt.%; the ethylene content—based on (B12)—is accordingly 60 to 75 wt.%, preferably 63 to 70 wt.%. The weight fractions refer respectively to the homopolymerized structural units of the monomers in the ethylene copolymer (B12).

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 containing 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.

Component B1) is particularly preferred to be 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 content of 1-butene - based on (B12) - is 25 to 40 wt.%, preferably 30 to 37 wt.%.

As an ethylene homopolymer B11), high-density polyethylene (HDPE) is generally used, preferably HDPE with a density of 950 to 970 kg/m³.

The production of HDPE is known to the expert.

Furthermore, HDPE is commercially available; for example, HDPE with a density of 950 to 970 kg/m³ is available from Tosoh Co., Ltd. as Nipolon® Hard, or from Borealis as Bormed® HE2581-PH and Bormed HE7541-PH.

Ethylene copolymer B12 is usually produced by copolymerizing ethylene and an alpha-olefin comonomer using a metallocene catalyst. Suitable metallocene catalysts are organic compounds of a transition metal with several (the number corresponding to the oxidation state of the transition metal) ligands coordinated to the transition metal, wherein at least one ligand is a cyclopentadienyl group. The transition metal is preferably selected from the group consisting of Zr, Ti, Hf, V, Nb, Ta and Cr; particularly preferably Zr or Hf, and most particularly preferably Zr.

Preferred is a zirconium or hafnium metallocene catalyst with two cyclopentadienyl groups.

The metallocene catalyst bis(n-butylcyclopentadienyl)zirconium dichloride is particularly preferred.

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 clay. Any usual clay materials can be used as clay, preferably hectorite, smectite, and montmorillonite.

The organically modified montmorillonite is obtained by reacting montmorillonite with an aliphatic salt. Examples of such aliphatic salts include N,N-dimethyldecylammonium chloride, N,N-dimethyldodecylammonium chloride, N,N-dimethyltetradecylammonium chloride, N,N-dimethylhexadecylammonium chloride, N,N-dimethyl-octadecylammonium chloride, N,N-dimethyl-behenylammonium chloride, N,N-dimethyl-behenylammonium fluoride, N,N-dimethyl-behenylammonium bromide, and N,N-dimethyl-behenylammonium iodide, preferably N,N-dimethyl-behenylammonium chloride.

Preferably, during the production of the ethylene copolymer B12), an organoaluminum compound, preferably triisobutylaluminum, is used as a co-catalyst.

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

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

Ethylene copolymer B12 is a high-density ethylene copolymer. Preferably, the ethylene copolymer B12 has a density of 945 to 960 kg/m³.

Component B2)

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

The term "terpolymer" refers to a copolymer that is made from three different monomers.

The term "propylene terpolymer" refers to a polypropylene molecular chain modified by two additional comonomers during the polymerization process. Preferred additional comonomers are ethylene and/or at least one C4-C12 alpha-olefin, preferably a C4-C8 alpha-olefin, particularly preferably ethylene and a C4-C8 alpha-olefin, and most particularly preferably ethylene and 1-butene.

The ethylene content is preferably 1 to 4 wt.%, and the content of at least one C4-C8 α-olefin, particularly 1-butene, is preferably 9 to 12 wt.%, each based on (B2). The weight fractions refer respectively to the homopolymerized structural units of the monomers in the terpolymer (B2).

In particular, propylene terpolymer (B2) composed of structural units of propylene, ethylene, and butylene is preferred.

The production of propylene terpolymers is known. Furthermore, suitable propylene terpolymers are commercially available, for example from Borealis, Austria.

Component B3)

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, and particularly preferably 8 carbon atoms.

Ethylene/alpha-olefin copolymers B3) preferably have a density in the range of 600 to 950 kg/m³, particularly preferably 750 to 900 kg/m³.

The proportion of the monomer units of the alpha-olefin - based on (B3) - is more than 8 wt.%, preferably more than 10 wt.%, particularly 20 to 30 wt.%.

Preferably, component B3) is an ethylene-1-octene copolymer.

Suitable polyethylene elastomers are commercially available, for example from Dow Chemical Company, USA.

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 units of propylene, ethylene, and butylene (component B2), and an ethylene-1-octene copolymer (component B3).

In particular, 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).

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)

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.-%, and especially preferably 75 to 85 wt.-% of the entire multilayer film, and serves to improve the impact toughness of the entire structure.

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)

Component C1) is at least one, preferably one, propylene terpolymer. The propylene terpolymer C1) is defined as component B2); reference is made to the corresponding descriptions regarding component B2).

Component C2)

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

The term "Styrol-Blockcopolymer Elastomer" refers to synthetic thermoplastic elastomers based on styrene block copolymers, which are used as impact modifiers.

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, particularly SEBS.

Suitable styrene block copolymer (SBC) elastomers C2) are commercially available, for example from Asahi Kasei, Japan.

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

Preferably, component C2) is a styrene block copolymer (SBC) elastomer, which contains no fractions of a thermoplastic elastomer based on olefins.

Component C3)

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.

Ethylene/alpha-olefin copolymers (C3) generally have a density in the range of 440 to 860 kg/m³.

The proportion of monomerized structural units of the alpha-olefin, based on (C3), is more than 8 wt.%, preferably more than 10 wt.%, particularly 20 to 30 wt.%.

Preferably, component C3) is an ethylene-1-butene copolymer, an ethylene-1-hexene copolymer, or an ethylene-1-octene copolymer, particularly preferably an ethylene-1-octene copolymer.

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

In particular, the middle polymer layer (C) according to the invention contains (or is composed of) 65 to 80 wt.%, preferably 72 to 78 wt.%, of a propylene terpolymer (component C1) consisting of units of propylene, ethylene, and butylene; 17 to 22 wt.%, preferably 19 to 21 wt.%, of a styrene-ethylene-butylene-styrene block copolymer (SEBS) (component C2); and 4 to 10 wt.%, preferably 5 to 8 wt.% of an ethylene-octene copolymer (component C3).

Function layer (D)

The heat-sterilizable multilayer film according to the invention can further include an additional functional layer D) as an outer layer, which is adjacent to the first polymer layer (A) on the outer side of (A) (i.e., on the opposite side of (A) from the one facing the polymer layer (C)).

The functional layer (D) preferably ensures that the heat-sterilizable multilayer film, as well as packaging made from it, such as medical bags or foil tubes produced from it, are airtight and/or waterproof.

Function layer D) 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 oxide (SiOx), aluminum oxide (AlOx) and acrylate-based polymers.

Preferably, the functional layer (D) is made of PET/SiOx.

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

A functional layer (D) made of PET/SiOx significantly improves the gas barrier (e.g., oxygen barrier) of the heat-sterilizable multilayer film according to the invention, making the film also well suitable for storing oxygen-sensitive active ingredients.

By means of a SiOx/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 cm³/(m² x day) ASTM F1927 (23°C, 50% r.H.).

Multi-layer film

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

The multilayer film can contain conventional additives and/or processing aids suitable for the intended use of the multilayer film in conventional amounts in each of the polymer layers (A), (B), and (C).

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).

The heat-sterilizable multilayer film according to the invention preferably contains at least one antioxidant, thermal stabilizer and/or acid scavenger, preferably in a total amount of less than 3000 ppm, based on the entire multilayer film.

Preferably, the polymer layers (A), (B), and (C) adhere to each other without using an adhesion promoter, i.e., the multilayer film according to the invention comprising the polymer layers (A), (B), and (C) preferably contains no adhesion promoter. Furthermore, preferably at least the second polymer layer (B) contains no additional additives and/or processing aids (e.g., modifiers or plasticizers, such as mineral oil), and particularly preferably none of the polymer layers (A), (B), and (C) contain any further additives and/or processing aids in addition to the aforementioned additives. Therefore, the multilayer film according to the invention as packaging material has no or only minimal influence on the medication or the medical solution during sterilization and storage.

In the case of an inventive multilayer film 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.

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.

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.

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 toughness of the entire structure.

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.

The total film thickness (= thickness) of the multilayer film according to the invention is preferably 50 to 500 µm, particularly preferably 100 to 400 µm, and very particularly preferably 150 to 300 µm.

The total 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 very particularly preferably 150 to 300 µm.

An especially preferred inventive multilayer film comprises the polymer layers (A), (B), and (C), and is characterized in that the total film thickness of the multilayer film is 50 to 500 µm, particularly preferably 100 to 400 µm, and—each value being based on the total film thickness of the multilayer film—the layer thickness of the first polymer layer (A) is 5 to 15 wt.%, preferably 7 to 13 wt.%; the layer thickness of the second polymer layer (B) is 5 to 15 wt.%, preferably 7 to 13 wt.%; and the layer 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 add up to 100 wt.%.

Process for the production of the multilayer film

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 co-extruded.

In co-extrusion, the plastic melts of the polymer layers (A), (B), and (C) are combined into the inventive multi-layer film before exiting the profile die of an extruder.

Often, the extrusion process is 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 (compounding extruders), heating-cooling mixers or pelletizing presses. Then, the molten plastics of the polymer layers (A), (B) and (C) are combined in another, directly coupled or spatially and temporally separated extruder before exiting through the profile die to form the multilayer film according to the invention.

The multilayer film obtained by the inventive process is preferably shock-cooled with water.

By co-extrusion, the inventive multi-layer film can be obtained in the form of a flat film (flat film process, e.g., using a slot die) or a tubular film (blown film process, e.g., inflating the interior of the tubular film with air—preferably sterilized filtered air), wherein in the case of a tubular film, the outer side consists of the first polymer layer (A) and the inner side consists of the second polymer layer (B).

The multilayer film obtained by the inventive process can, in a further process step, have the optional functional layer (D) applied to it—for example, by heat lamination or preferably by laminating.

According to a specific embodiment for manufacturing a laminated multi-layer film tube according to the invention, the inventive method comprises the following steps: (a') producing a film tube from the multi-layer film according to the invention by co-extruding 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 sterilized filtered air; (b') optionally cooling the film tube produced in step (a'); (c') coating the optionally cooled film tube with an adhesive primer layer on at least one side (the first polymer layer (A)) of the film tube; (d') optionally drying the film tube provided with the adhesive primer layer; (e') laminating at least one side (the first polymer layer (A)) of the film tube coated with the adhesive primer layer with a functional layer (D), in particular a SiOx/PET functional layer; (f') optionally drying or curing the laminated film tube.

According to the inventive method of the aforementioned embodiment, the two parallel inner sides (second polymer layers (B)) of the film tube preferably directly adhere to each other after the melting or co-extrusion of the film tube, thus making it possible to coat the outer sides (first polymer layers (A)) of the film tube when the inner space of the film tube is closed. The resulting closed inner space, which will be inflated during later use of the resulting film tube, is thereby essentially particle-free.

Preferably, in the inventive method of the aforementioned embodiment, the inner space of the film tube is flooded with sterile filtered air, resulting in a particle-free, masked multi-layer film tube that is particularly suitable for medical purposes.

The aforementioned inventive method is particularly preferred for producing a particle-free, coated multi-layer tube in a clean room.

In the inventive method according to the above embodiment, a primer is preferably used which allows complete curing at room temperature after approximately 2 weeks, preferably 1 week. In a heating chamber, curing at an elevated temperature, preferably 30°C or higher, often 40°C to 60°C, can take place more quickly.

Suitable adhesives (bonding agents, adhesives or lamination adhesives) include, for example, isocyanates, polyurethanes, poly(ethyl acrylate/methacrylic acid ester), acrylic copolymers, vinyl ester/acrylic copolymers, or inorganic-organic hybrid polymers.

Preferred adhesion promoters are two-component systems that can be solvent-containing or solvent-free, and can contain silicones or be silicone-free, and can optionally be used with an additional "catalyst" to accelerate curing.

Suitable solvent-containing 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.

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

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 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.

Alternatively, also one-component systems can be used as adhesion promoters, which may contain solvents or be solvent-free, and may contain silicones or be silicone-free, and optionally can be used with an additional "catalyst" to accelerate curing.

Suitable solvent-free one-component systems are, for example, Dow MOR-FREE™ ELM 415A (polyurethane adhesive) or SENOBOND®-WB-FILM LAMINATING ADHESIVE FP NDC 375224, which are commercially available.

The adhesive is particularly chosen to meet the requirements of pharmacopoeia limits, for example regarding migration properties, and preferably is free from organic solvents.

The adhesive layer can be applied to the tubular film produced by co-extrusion, either on one side or both sides, depending on the method used or the desired coating. This can, for example, be done by spraying or doctor-blading. The use of aqueous solutions of the corresponding adhesives is also suitable.

After applying these adhesive layers, the resulting film tube may be dried if necessary. For example, if the application of the adhesive is carried out using water, drying can occur through evaporation of the water.

The thickness of the primer adhesive layers preferably lies in the range of 3 to 10 µm.

The invention also relates to the use of the multilayer film according to the invention for producing a medical packaging, preferably a medical bag.

Also the use of the inventive medical packaging, preferably as a container for at least one medication, is the subject of the invention.

The inventive medical packaging is particularly suitable as a container for at least one medication, wherein due to the combination of one

Outer and middle layers based on polypropylene (polymer layers (A) and (C)) with an inner layer based on polyethylene (polymer layer (B)), which ensures excellent processability on all common bag sealing machines, while the polyethylene of the inner layer exhibits a particularly low tendency for adsorption of medicinal active ingredients.

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, for example, relevant for certain medication combinations that must be administered together but are not stable over longer periods when combined, or for solid medications that are administered in the form of a solution or suspension but are not stable over longer periods in the solution or suspension. By using separate chambers, the components of the final dosage form can be stored separately and mixed together shortly before administration by opening the separating sections.

A method for producing an inventive medical packaging, preferably a bag, comprises the steps of: 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) shaping a medical packaging, preferably a bag, from at least one heat-sterilizable multilayer film, such that the second polymer layer (B) forms the inner surface of the medical packaging, preferably of the bag, and the first polymer layer (A) forms the outer surface of the medical packaging, preferably of the bag; d) optionally positioning the port elements and/or tubes between the inner surfaces at the contours of the medical packaging, preferably of the bag; e) bringing together the inner surfaces at the contours of the medical packaging, preferably of the bag, with each other and optionally with positioned port elements and/or tubes in between; f) welding the inner surfaces at the contours of the medical packaging, preferably of the bag, together with each other and optionally with positioned port elements and/or tubes in between.

In step a), the inventive multilayer film is preferably provided in the form of a flat film or a tubular film. Depending on the provided form of the film, the further process may differ in certain details. The obtained particle-free film tube can be coated with a functional layer (D), for example, a SiOx/PET functional layer, through additional processing steps.

Depending on the application of the inventive medical packaging, preferably the bag, additional elements such as, for example, port elements and/or tubes may optionally be provided in step b) after the provision of the inventive multilayer film. The provision of these elements is, for example, meaningful when the inventive medical packaging, preferably the bag, is intended to be used as a permanent component of a medical device or connected to a medical device. Omitting step b) may, for example, be meaningful when the medical packaging, preferably the bag, is merely used for storing a medication and is damaged, for example, by tearing or puncturing with a needle for removing the medication.

In step c), the provided inventive multilayer film is formed into the shape of a medical packaging, preferably a bag. If a tubular film was provided in step a), forming the medical packaging, preferably the bag, may involve, for example, simply 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 of the tubular film. If a flat film was provided in step a), then in step c), the medical packaging, preferably the bag, can be formed, for example, from a single piece of multilayer film by cutting this piece into a symmetrical shape and folding it along the axis of symmetry.So that the edges of the film overlap exactly, with the second polymer layer (B) on the inside. Alternatively, the medical packaging according to the invention, preferably the bag, can be formed from two pieces of flat film by cutting the two pieces in a mirror-symmetrical manner and overlapping them exactly, with the second polymer layer (B) on the inside. During the cutting process, rectangular shapes are particularly preferred, since this results in the least material loss and the easiest processing. However, other shapes are also possible, so that, for example, a medical packaging, preferably a bag, can be produced with an aesthetic shape that is appealing to children and thus distracts them from the actual administration of a medication.

Depending on whether additional elements such as port elements and/or tubes were provided in step b), these elements can be positioned in step d) between the inner surfaces along the contours of the formed medical packaging, preferably the bag. In the case of a tube film, this refers to inserting the additional elements into the openings of the tube film. In this case, the elements can only be positioned on two opposite sides of the medical packaging, preferably the bag. In the case of a flat film, this refers to inserting the additional elements between the edges of one or more flat film pieces that are placed on top of each other in register in step c). In this case, the elements can be positioned at any location along the edges, preferably at most on two opposite edges.

In step e), the inner surfaces of the formed medical packaging, preferably those of the bag, are brought into contact with each other and with any additional elements that may be located between the inner surfaces, so that they can be welded together in step f) by applying heat and, if necessary, mechanical pressure. During welding, the temperature is preferably chosen to be 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 at the contours of the medical packaging, preferably the bag, thus sealing it firmly and fluid-tight, while the first polymer layer (A) retains its shape, thereby providing stability to the medical packaging, preferably the bag.

An important criterion for using the inventive multilayer film as a primary packaging material for medical solutions is its barrier effect against liquid loss. Such liquid loss leads to a concentration of the active ingredients in the solution, which must not exceed certain values. The liquid loss during storage, among other factors, determines the shelf life of the product. The formulation of the inventive multilayer film is chosen such that, with good impact toughness, an excellent water vapor barrier is achieved.

The multi-layer film according to the invention is characterized in that it is heat sterilizable, impact-resistant, and flexible (without plasticizers), and can be reliably welded with a thermally permanently heated welding method even with port elements, and in that it further exhibits good adhesion between the individual layers without requiring an adhesion promoter, and does not or at least hardly influences medical solutions or medications.

The multilayer films according to the invention, which are provided with an additional functional layer (D), in particular a SiOx/PET functional layer, exhibit a significantly improved gas barrier, allowing also the storage of oxygen-sensitive ingredients.

The invention will now be explained in more detail with examples, without thereby limiting it.

Example 1:

First polymer layer (A): 97 wt.% Moplen® HP525J from Lyondell Basell Corp., USA / Polypropylene homopolymer 3 wt.% Tuftec® H1062 from Asahi Kasei, Japan / Styrene-ethylene/butylene block copolymer

The stated formulation was homogeneously mixed in a separate compounding step in the molten state, extruded, and pelletized for further use.

Second polymer layer (B):

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

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

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

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 blown film line with water cooling using conventional processing parameters for polypropylene, resulting in a multi-layer film in the form of a tubular film, whose inner space was flooded with sterile filtered air.

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

The produced film is suitable for hot steam sterilization and can already be firmly welded with welding tools tempered at 125°C.

Example 2:

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

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

The produced film is suitable for sterilization with hot steam and can already be firmly welded with welding tools preheated to 125°C.

Example 3 (Comparative example according to DE 10361851 A1, Example 1) First polymer layer (A):

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

The mentioned formulation was mixed in a separate compounding step in the molten state and granulated for further use.

Second polymer layer (B):

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

The stated formulation was mixed in a separate compounding step in the molten state and pelletized for further use.

Middle polymer layer (C):

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

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

The film was manufactured with a total thickness of 200 µm, where the first polymer layer (A) and the second polymer layer (B) each have a thickness of 15 µm, and the middle polymer layer (C) has a thickness of 170 µm. The produced film is steam-sterilizable and can be firmly welded using tempered welding tools at 125°C.

Example 4 (not in accordance with the invention, comparison) First polymer layer (A):

Second polymer layer (B):

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

Middle polymer layer (C):

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

The granulated compounds of the polymer layers (A), (B), and (C) were co-extruded on a blown film line with water cooling using typical processing parameters for polypropylene, resulting in a multi-layer film in the form of a tubular film.

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

Investigation of Weld Seam Strength (WSS) of the films from Examples 1 to 4

1. (a) Preparation of welded samples using a foil welding device (IST Med by Kopp) from two overlapping foils (each 20 x 15 cm); welding area (foil edge) - 15 mm. Welding parameters: Pressure: 2-3 bar, Time: 1-2 seconds, Gap: 320 µm. (b) Subsequently, punching of test strips with a width of 15 x 80 mm with a welded edge (= non-sterilized samples). 2. Heat steam sterilization at 121°C (autoclave WEBECO Type A 35, 2 bar, 20 minutes) of some of the obtained test strips with a welded edge (= heat steam sterilized samples). To prevent the foils from sticking together, the non-welded areas of the test strips are opened beforehand and paper is placed between them. 3. Determination of the weld strength by clamping the cooled test strips with a welded edge into a tensile testing machine (Zwick iLine 500N by Zwick) and pulling the test strips with a tensile speed of 400 mm/min.

The results for the weld seam evaluation are given in N/15mm.

The weld strength of the multi-layer film should be more than 25 N/15 mm, preferably more than 30 N/15 mm. If the weld strength of the multi-layer film is between 10 to 20 N/15 mm, it is considered a peel joint.

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

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

The individual examples are marked by different line structures in the figures.

Results: (a) Non-sterile samples

The welding curves (see Figure 1) of the films from Examples 1, 3 and 4 show an SNF of >30N/15mm at about 130°C; the film from Example 2 with the PET/SiOX functional layer starts to weld approximately 5°C higher (SNF >30N/15mm), which is not a problem due to the higher temperature resistance of the film provided by the PET/SiOX functional layer.

(b) Hot steam sterilized samples

The welding curves (see Figure 2) of the films from Examples 1, 2, and 3 are similar to those of the non-sterilized samples, i.e., they exhibit an SNF of >30N/15mm at approximately 130°C or 135°C; the film from Example 4 (second polymer layer on an LDPE base) does not show the desired weld strength after steam sterilization. The weld breaks apart or "peels" off or delaminates. If films according to Example 4 were used as medical bags, the bags would open during sterilization in the autoclave or when being removed.

PE materials such as LDPE or HDPE are not compatible with polypropylene, i.e., in the case of multi-layer films with middle layers based on PP, the inner layer can easily separate from the middle layer. Furthermore, the melting temperature of LDPE raw material is between 110 and 115°C, i.e., the raw material melts during hot steam sterilization and weakens the weld seam.

It has been found that the inventive multilayer film according to examples 1 and 2, due to the specific combination used for the second polymer layer (inner layer) B), consisting of a composite B1) based on polyethylene, a PP terpolymer B2), and a polyethylene elastomer B3) (as an adhesion promoter), has the advantage that the inner layer B) does not easily separate from the middle layer C). Furthermore, the composite B1) does not melt during hot steam sterilization, thus maintaining sufficient weld strength.

Compared to multilayer films of the prior art as described in Example 3 (inner layer B made of impact-modified propylene terpolymer), the multilayer films of the inventive examples 1 and 2 also exhibit very good impact strength—due to the composite B1 used for inner layer B—which is based on polyethylene—without the addition of an impact modifier. They have a comparable seam strength and suitability for steam sterilization. Furthermore, the inventive multilayer films offer the advantage over those of Example 3 that active ingredients adhere less strongly to the PE-containing inner layer, i.e., the so-called "recovery value" is higher.

Claims

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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 (SiO_x), aluminum oxide (AlO_x) and acrylate-based polymers.
Heat-sterilizable multilayer film according to claim 15, in which functional layer (D) consists of PET/SiO_x.
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.
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.
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.