Styrene butadiene block copolymer compositions suitable for medical devices

Abstract

The present invention relates to transparent and flexible styrene-butadiene copolymer compositions having high softness and temperature resistance as well as good processability, and methods for their preparation. Furthermore, the present invention relates to shaped articles produced from the polymer compositions of the present invention, and to the use of the polymer compositions for the production of shaped articles, in particular for medical applications, in particular medical drip chambers.

Description

[0001] describe

[0002] The present invention relates to transparent and flexible styrene-butadiene copolymer compositions having high softness and temperature resistance as well as good processability, and a method for their preparation. Furthermore, the present invention relates to shaped articles made from these (SBC) polymer compositions and to the use of these polymer compositions for the production of shaped articles, in particular for medical applications, in particular medical drip chambers.

[0003] Transparent and flexible medical devices used to transport any kind of fluid during medical procedures, such as medical tubing and bags, are typically made from plasticized polyvinyl chloride (PVC). However, the use of plasticized PVC has several disadvantages, notably the migration of harmful plasticizers from PVC into the human body and adverse environmental impacts during the disposal of PVC-based waste.

[0004] Several polymeric materials have been developed as alternatives to plasticized PVC. These polymeric materials often do not possess all the physical and mechanical properties required for specific medical applications. Generally, suitable polymeric materials are flexible, transparent, and elastic, and exhibit sufficient thermal stability, such as is required for steam sterilization of medical devices. Another requirement for polymeric materials is good processability, as medical devices are typically manufactured for single use due to public health concerns and are therefore typically produced in large quantities.

[0005] For example, WO 2001 / 94466 and WO 2012 / 037462 describe flexible medical tubing made from a composition comprising a polyolefin, such as polypropylene, and a styrene-butadiene block copolymer.

[0006] Documents WO 2018 / 166958 and WO 2018 / 166950 describe polymer compositions comprising star-shaped styrene-butadiene copolymers and plasticizers and their use in medical applications, such as medical tubing and medical bags. Document WO 2016 / 034609 proposes polymer blends comprising different styrene-butadiene copolymers, wherein the blends should exhibit high transparency, good thermoforming behavior, and improved multiaxial toughness.

[0007] WO 1996 / 24634 describes a medical molded component, for example a component for a perfusion or blood transfusion system. The medical component is made from a polymer mixture containing a rubber-elastic block copolymer and optionally another thermoplastic polymer.

[0008] Modern injection molding machines for producing medical devices such as drip chambers produce a large number of products, resulting in an ever-increasing number of mold cavities. Therefore, it is necessary to provide polymer compositions with excellent processing properties, such as a high melt flow rate. In particular, an optimized melt flow rate is necessary to ensure that all mold cavities are filled without defects. To achieve good demoulding properties, release agents are usually added to thermoplastic polymer compositions. The addition of release agents usually reduces thermal stability, for example, by lowering the Vicat temperature. However, for some medical applications, sufficient thermal stability is essential, for example, for sterilization and rapid demoulding during processing.

[0009] Furthermore, medical devices must be soft to allow for easy extrusion and deformation, and therefore exhibit a low Shore D hardness. Consequently, plasticizers are often added, which often negatively impact thermal stability and transparency. Consequently, it is desirable to avoid or reduce their use. Furthermore, medical devices must quickly recover their original shape after deformation, such as extrusion. Medical devices must exhibit high flexibility / elasticity. These conflicting properties require thorough optimization and balancing of various performance characteristics.

[0010] One object of the present invention is to provide a polymer composition that can be advantageously used in transparent, flexible medical devices, such as drip chambers, and that has the above-mentioned property balance within given target values. In particular, the polymer composition should have improved thermoforming behavior and be suitable for mass production without sacrificing the other properties mentioned above.

[0011] Surprisingly, it has been found that the polymer compositions of the present invention comprising defined vinyl aromatic hydrocarbon / conjugated diene copolymers, particularly styrene butadiene block copolymers, can achieve this balance of properties, including improved processing properties and thermoforming behavior. In particular, it has been found that optimized melt flow rates, particularly exceeding 25 cm 3 / 10min, preferably at 25 to 40cm 3 A flow rate of 1000 rpm / 10 min (ISO 1133-1:2011, 200°C, 5 kg) is necessary to ensure that all cavities are free of defects during the injection molding process. Preferably, the polymer composition according to the present invention does not require any plasticizers and is PVC-free.

[0012] The present invention relates to a polymer composition comprising (preferably consisting of):

[0013] P1. Based on the total polymer composition, 65 to 100% by weight, preferably 68 to 100% by weight, more preferably 80 to 100% by weight of at least one block copolymer P1 comprising at least one vinyl aromatic monomer and at least one diene monomer, the block copolymer P1 comprising

[0014] 65 to 80% by weight, based on the block copolymer P1, of at least one hard block A1 comprising 90 to 100% by weight, preferably 95 to 100% by weight, based on the total hard blocks A1, of vinyl aromatic monomers and 0 to 10% by weight, preferably 0 to 5% by weight, based on the total hard blocks A1, of diene monomers, and

[0015] 20 to 35% by weight, based on the block copolymer P1, of at least one soft block B1 comprising 0 to 10% by weight, based on the total soft blocks B1, of vinyl aromatic monomers and 90 to 100% by weight, based on the total soft blocks B1, of diene monomers;

[0016] P2. 0 to 35 wt. %, preferably 0 to 32 wt. %, more preferably 0 to 20 wt. %, based on the total polymer composition, of at least one elastomeric block copolymer P2 comprising at least one vinyl aromatic monomer and at least one diene monomer, said block copolymer P2 comprising

[0017] 28 to 40% by weight, based on the block copolymer P2, of at least one hard block A2 comprising 90 to 100% by weight, preferably 95 to 100% by weight, based on the total hard blocks A2, of vinyl aromatic monomers and 0 to 10% by weight, preferably 0 to 5% by weight, based on the total hard blocks A2, of diene monomers, and 60 to 72% by weight, based on the block copolymer P2, of at least one soft block B2 comprising 30 to 60% by weight, based on the total soft blocks B2, of vinyl aromatic monomers and 40 to 70% by weight, based on the total soft blocks B2;

[0018] P3. Based on the total polymer composition, 0 to 20% by weight, preferably 0 to 10% by weight of one or more additional non-elastic thermoplastic polymers P3;

[0019] C. 0 to 1.5% by weight, preferably 0 to 0.15% by weight, based on the total polymer composition, of at least one mold release additive C;

[0020] D. 0 to 10% by weight, preferably 0 to 5% by weight, based on the total polymer composition, of one or more additional additives D,

[0021] with the proviso that the sum of components P1 and P3 is equal to or greater than 75% by weight, preferably equal to or greater than 75.5% by weight, of the weight of the total polymer composition; and

[0022] Provided that, if the amount of component P1 is less than 80 wt. % of the total polymer composition, the composition comprises, based on the total polymer composition, 5-20 wt. %, preferably 6-20 wt. %, more preferably 6-10 wt. % of component P3.

[0023] Preferably, the sum of components P1 and P3 is 75 to 100% by weight, preferably 75.5 to 100% by weight, based on the total polymer composition.

[0024] For the purposes of the present invention, an "elastomeric polymer" (or also referred to as an elastomer) is a polymer that exhibits rubber-like elasticity. Preferably, the elastic modulus (also referred to as tensile modulus) of the elastomeric polymer is less than 500 MPa, preferably less than 150 MPa (determined according to ISO 527). Preferably, the elastomeric polymer has a strain at break (determined according to ISO 527) of 350% or more, preferably 400% or more and / or a Vicat temperature (Vicat A / 50 determined according to ISO 306) of 65° C. or less, preferably 50° C. or less.

[0025] In the present invention, "non-elastic polymer" refers to a polymer that does not exhibit rubber-like elasticity.

[0026] Preferably, the elastic modulus (also called tensile modulus) of the non-elastic polymer is equal to or higher than 500 MPa, preferably equal to or higher than 1000 MPa (determined according to ISO 527). Preferably, the non-elastic polymer has a strain at break of equal to or lower than 10%, preferably equal to or lower than 5% (determined according to ISO 527) and / or a Vicat temperature (Vicat B / 50 determined according to ISO 306) of equal to or higher than 83° C., preferably equal to or higher than 100° C.

[0027] In the context of the present invention, "diene" refers to a conjugated diene.

[0028] In the context of the present invention, ppm (parts per million) means mg / kg (milligrams per kilogram) and pph (parts per hundred) means 10 g / kg (ten grams per kilogram).

[0029] In the context of the present invention, the average molecular weight MW is determined by gel permeation chromatography (GPC) according to ISO 16014-3:2012 (low temperature T<60° C., size exclusion, relative calibration with polystyrene in THF as standard).

[0030] Typically, the glass transition temperature (Tg) of the polymer block depends on the monomer composition and the 1,2-vinyl content of the diene units. Typically, the glass transition temperature (Tg) of the polymer block can be determined using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) or differential thermal analysis (DTA) or calculated according to the Fox equation. Typically, the glass transition temperature (Tg) of the hard block (also referred to as the hard phase), such as the glass transition temperature (Tg) of the hard blocks A1 and A2, is equal to or greater than 40°C, preferably equal to or greater than 50°C, and the glass transition temperature (Tg) of the soft block (also referred to as the soft phase), such as the temperature of the soft blocks B1 and B2, is equal to or less than 0°C, preferably equal to or less than -30°C.

[0031] Preferably, the polymer composition has a melt volume flow rate (MVR) of 24 to 40 cm2, measured on a polymer melt at 200°C and a load of 5 kg according to ISO 1133-1:2011. 3 / 10min range, preferably 25 to 40cm 3 / 10 minutes, more preferably 25 to 38 cm 3 / 10 minutes, more preferably 25.2 to 38 cm 3 / 10 minutes, more preferably 25.2 to 35.2 cm 3 / 10 minutes.

[0032] In another embodiment, the polymer composition of the present invention has a melt volume flow rate (MVR) of 30 to 40 cm², measured on the polymer melt at 200°C and 5 kg load according to ISO 1133-1:2011. 3 / 10min, more preferably between 30 and 38cm 3 / 10min, more preferably in the range of 31 to 36cm 3 / 10min, more preferably in the range of 30.0 to 35.2cm 3 / 10min, most preferably in the range of 31 to 35.2cm 3 / 10min range.

[0033] Preferably, the polymer composition or the molded article produced therefrom exhibits a Shore D hardness (measured after 15 seconds) in the range of 50 to 68, preferably in the range of 50 to 62, more preferably in the range of 55 to 62, determined according to ASTM D2240.

[0034] Preferably, the polymer composition or the molded article produced therefrom has a modulus of elasticity (E-modulus), measured according to ISO 527 (e.g. on a Zwick tensile tester with a 2.5 kN + 500 N load cell), of greater than 1000 MPa, preferably greater than 1020 MPa, more preferably greater than 1050 MPa, in particular greater than 1100 MPa.

[0035] Preferably, the polymer composition of the present invention or the molded articles produced therefrom exhibit a Vicat temperature Vicat A / 50 measured according to ISO 306:2004 of greater than 68°C, preferably greater than 70°C, more preferably greater than 73°C.

[0036] In particular, the vinyl aromatic monomer of components P1 and P2 is at least one monomer selected from styrene or substituted styrenes. For example, one or more substituted styrenes according to the following formula (I):

[0037]

[0038] in

[0039] R is hydrogen or C1-C8-alkyl; R 1 is hydrogen or C1-C8-alkyl;

[0040] The premise is that R and R 1 It's not all hydrogen, and

[0041] q is 1, 2 or 3, preferably 1 or 2;

[0042] The substituted styrenes can be used alone or in combination with unsubstituted styrenes as the vinyl aromatic monomer in components P1 and P2. Preferably, the at least one vinyl aromatic monomer is selected from styrene, α-methylstyrene and vinyltoluene, more preferably styrene, α-methylstyrene or a mixture thereof.

[0043] In particular, the diene monomer of components P1 and P2 is at least one monomer selected from 1,3-butadiene, isoprene, 1,3-pentadiene and 1-phenylbutadiene. More preferably, the diene monomer of components P1 and P2 is 1,3-butadiene.

[0044] In a particularly preferred embodiment, the vinyl aromatic monomer of components P1 and P2 is styrene and the diene monomer of components P1 and P2 is 1,3-butadiene.

[0045] In a preferred embodiment, the polymer composition of the present invention comprises:

[0046] P1. Based on the total polymer composition, 80 to 100% by weight, preferably 82 to 100% by weight of at least one block copolymer P1;

[0047] P2. 0 to 20% by weight, preferably 0 to 18% by weight, of at least one elastomeric block copolymer P2, based on the total polymer composition;

[0048] P3. 0 to 20% by weight, preferably 0 to 10% by weight, of one or more additional non-elastic thermoplastic polymers P3, based on the total polymer composition,

[0049] C. 0 to 0.15% by weight, preferably 0.01 to 0.15% by weight, based on the total polymer composition, of at least one mold release additive C;

[0050] D. 0 to 10% by weight, preferably 0 to 5% by weight, more preferably 0 to 2.5% by weight, of one or more additional additives D, based on the total polymer composition.

[0051] In another preferred embodiment, the polymer composition of the present invention comprises:

[0052] P1. 79.99 to 99.99% by weight, preferably 81.98 to 98.98% by weight, of at least one block copolymer P1, based on the total polymer composition;

[0053] P2. 0 to 20% by weight, preferably 1 to 18% by weight, of at least one elastomeric block copolymer P2, based on the total polymer composition;

[0054] P3. 0 to 10% by weight, preferably 0 to 8% by weight, of one or more additional non-elastic thermoplastic polymers P3, based on the total polymer composition,

[0055] C. 0.01 to 0.15% by weight, preferably 0.02 to 0.1% by weight, based on the total polymer composition, of at least one mold release additive C;

[0056] D. 0 to 5% by weight, preferably 0 to 2.5% by weight, of one or more additional additives D, based on the total polymer composition.

[0057] Block copolymer P1

[0058] The polymer composition comprises at least 65% by weight, preferably at least 68% by weight, based on the total polymer composition, of at least one block copolymer P1 comprising (preferably consisting of) at least one vinyl aromatic monomer and at least one diene monomer, wherein the block copolymer P1 comprises (preferably consists of):

[0059] 65 to 80% by weight, based on the block copolymer P1, of at least one hard block A1 comprising (preferably consisting of), based on the weight of the total hard blocks A1, 90 to 100% by weight, preferably 95 to 100% by weight, more preferably 98 to 100% by weight, of vinyl aromatic monomers, in particular styrene, and 0-10% by weight, preferably 0-5% by weight, more preferably 0-2% by weight, based on the weight of the total hard blocks A1, of diene monomers, in particular 1,3-butadiene, and

[0060] 20 to 35% by weight, based on the block copolymer P1, of at least one soft block B1 comprising (preferably consisting of) 0 to 10% by weight, preferably 0 to 5% by weight, based on the weight of the total soft block B1, of vinyl aromatic monomers, in particular styrene, and 90-100% by weight, preferably 95-100% by weight, based on the weight of the total soft block B1, of diene monomers, in particular 1,3-butadiene.

[0061] In a preferred embodiment, the hard block A1 consists of 100% by weight of styrene.

[0062] In particular, the block copolymer P1 is a styrene butadiene block copolymer. Preferably, the block copolymer P1 is a star block copolymer, more preferably a star styrene butadiene block copolymer.

[0063] In a preferred embodiment, the melt volume flow rate (MVR) of the block copolymer P1 is measured according to ISO 1133-1:2011; load 200°C / 5 kg, at 30-40 cm 3 / min, more preferably in the range of 32-38cm 3 / min, most preferably in the range of 34-36cm 3 / min range.

[0064] In a preferred embodiment, the glass transition temperature Tg of the hard block A1 of the block copolymer P1 is higher than 80°C, and the glass transition temperature Tg of the soft block B1 of the block copolymer P1 is lower than -60°C, preferably -60 to -100°C, more preferably -70 to -100°C.

[0065] Preferably, at least one soft block B1 of the block copolymer P1 comprises, based on the soft block B1, 95 to 100% by weight, preferably 98 to 100% by weight, of a diene monomer, more preferably 1,3-butadiene. More preferably, at least one soft block B1 of the block copolymer P1 consists essentially of a diene monomer, preferably 1,3-butadiene.

[0066] In particular, the molecular weight MW of the soft block B1 of the block copolymer P1 is in the range of 8,000-40,000 g / mol, preferably in the range of 10,000-25,000 g / mol, more preferably in the range of 12,000-18,000 g / mol.

[0067] Typically, the molecular weights MW of the block copolymers P1 and P2 and / or the hard and soft blocks (A and B) of the block copolymers P1 and P2 are determined according to ISO 16014-3:2012 (size exclusion at low temperature T<60° C. with relative calibration using polystyrene in tetrahydrofuran as standard).

[0068] In a preferred embodiment, the block copolymer P1 comprises, based on the total weight of the block copolymer P1, 20-30% by weight, preferably 22-27% by weight, of a diene monomer, preferably 1,3-butadiene. Preferably, the block copolymer P1 comprises, based on the total weight of the block copolymer P1, 65 to 80% by weight, preferably 70 to 80% by weight, more preferably 73 to 78% by weight, of a vinyl aromatic monomer, preferably styrene.

[0069] Particularly preferably, the block copolymer P1 is a star-shaped styrene-butadiene block copolymer comprising at least one (branched) structure A1-B1.

[0070] Preferably, the block copolymer P1 is a radial block copolymer comprising at least two terminal hard blocks A1 composed of vinylaromatic monomers, in particular styrene, and one or more soft blocks B1, each composed of 98 to 100% by weight, preferably 100% by weight, of diene, in particular 1,3-butadiene, and 0 to 2% by weight of vinylaromatic monomers, in particular styrene.

[0071] Preferably, the weight proportion of the hard block A1 in the block copolymer P1 is 65-80% by weight, preferably 70-80% by weight, more preferably 73-78% by weight.

[0072] In particular, the molecular weight MW of the hard block A1 of the block copolymer P1 is in the range of 5,000-200,000 g / mol,

[0073] It is preferably in the range of 7,000-150,000 g / mol, more preferably in the range of 8,000-120,000 g / mol.

[0074] Preferably, the block copolymer P1 is a block copolymer having [A1-B1] n X or [A1-B1] nA Y-structured star block copolymer; wherein A1 is a vinyl aromatic hard block, B1 is a soft block, X is a free radical of an n-functional initiator, Y is a free radical of an n-functional coupling agent, and n is a natural number of 1-10, preferably 3-5.

[0075] Typically, such block copolymers are obtained by anionic polymerization of branches and coupling with epoxidized vegetable oils, such as epoxidized linseed oil or epoxidized soybean oil. In this case, a statistical distribution of star structures with varying numbers of branches is generated, with the most abundant star structures having 2 to 4 branches. The amount and composition of the hard blocks A1 and soft blocks B1 can be identical or different in the different branches of the star-shaped block copolymer P1.

[0076] Preferably, the block copolymer P1 comprises at least two terminal hard blocks A11 and A12 of different molecular weights, wherein the molecular weight MW of block A11 is in the range of 35,000-200,000 g / mol, preferably 50,000-150,000 g / mol, more preferably in the range of 90,000 to 125,000 g / mol, and the molecular weight MW of block A12 is in the range of 5,000 to 30,000 g / mol, preferably in the range of 6,500 to 20,000 g / mol, more preferably in the range of 7,500 to 15,000 g / mol.

[0077] Typically, such block copolymers can be obtained by sequential anionic polymerization of branches, wherein the initiator is added twice in the corresponding molar ratio and then coupled with a coupling agent, such as epoxidized vegetable oil (such as epoxidized linseed oil or epoxidized soybean oil).

[0078] Particularly preferably, the block copolymer P1 is a star-shaped block copolymer, preferably a star-shaped styrene-butadiene block copolymer, having the structure Y[A11-B1] m [A12-B1]1 or Y[A11-B1] m [A12-B1] l wherein A11 and A12 are hard blocks of different molecular weights as described above, B1 is a soft block as described above, Y is a group of an (m+1)-functional coupling agent, and m and l are natural numbers from 1 to 10, preferably from 1 to 5. Preferably, the ratio m / l is in the range of 1:2 to 1:5, more preferably from 1:3 to 1:5. Specifically, this ratio is a statistical ratio obtained during synthesis based on the molar initiation ratio of the two branches.

[0079] These block copolymers can be obtained by anionic polymerization and coupling with a coupling agent, as described in WO 2008 / 000623 (block copolymer A of WO 2008 / 000623).

[0080] Elastic block copolymer P2

[0081] The polymer composition of the present invention may comprise up to 35 wt.-%, preferably up to 32 wt.-%, more preferably up to 20 wt.-% of an elastomeric block copolymer P2 comprising (preferably consisting of) at least one vinyl aromatic monomer and at least one diene monomer, wherein the block copolymer P2 comprises (preferably consists of):

[0082] 28 to 40% by weight, based on the block copolymer P2, of at least one hard block A2 which comprises (preferably consists of) 90 to 100% by weight, preferably 95 to 100% by weight, based on the total hard blocks A2, of vinyl aromatic monomers, in particular styrene, and 0-10% by weight, preferably 0-5% by weight, based on the total hard blocks A2, of diene monomers, in particular 1,3-butadiene, and

[0083] 60 to 72% by weight, based on the block copolymer P2, of at least one soft block B2 which comprises (preferably consists of) 30 to 60% by weight, preferably 40 to 55% by weight, based on the total soft block B2, of vinyl aromatic monomers, in particular styrene, and 40-70% by weight, preferably 45-60% by weight, based on the total soft block B2, of diene monomers, in particular 1,3-butadiene.

[0084] In a preferred embodiment, the hard block A2 of the elastomeric block copolymer P2 consists of 100% by weight of styrene, based on the hard block A2.

[0085] Preferably, the soft block B2 of the elastomeric block copolymer P2 may have a random or tapered distribution of vinyl aromatic monomers and diene monomers. Preferably, the soft block B2 of the elastomeric block copolymer P2 may be composed of a plurality of continuous blocks B2 (e.g., B21-B22-B23) having different compositions and block lengths.

[0086] In particular, the elastomeric block copolymer P2 is a thermoplastic elastomer. In particular, the elastomeric block copolymer P2 is a styrene butadiene block copolymer.

[0087] The elastomeric block copolymer P2 may be a radial or linear block copolymer. Preferably, the elastomeric block copolymer P2 is a linear styrene-butadiene block copolymer, in particular a linear styrene-butadiene block copolymer having thermoplastic elastomer properties.

[0088] In a preferred embodiment, the glass transition temperature Tg of the hard block A2 of the elastomeric block copolymer P2 is above 50°C, and the glass transition temperature Tg of the soft block B2 of the elastomeric block copolymer P2 is below 0°C.

[0089] In a preferred embodiment, the elastomeric block copolymer P2 consists of two or more hard blocks A2 made from vinyl aromatic monomers and one or more random soft blocks B2, wherein B2 consists of 30 to 60% by weight, preferably 30 to 55% by weight, of vinyl aromatic monomers and 40-70% by weight, preferably 45-70% by weight, of diene. Preferably, P2 comprises (preferably consists of) the block sequence A2-B2 or A2-B2-A2, wherein the weight proportion of diene in the total block copolymer P2 is 27-46% by weight.

[0090] Preferably, the molecular weight MW of the at least one hard block A2 of the elastomeric block copolymer P2 is in the range of 5,000 to 100,000 g / mol, more preferably 10,000 to 50,000 g / mol.

[0091] In a preferred embodiment, the elastomeric block copolymer P2 has at least one of the following structures:

[0092] A2-B2-A2

[0093] X-[-B2-A2]2

[0094] Y-[-B2-A2] m

[0095] Y[(B2-A2) n ] m [A2] l and

[0096] Y[(A2-B2) n -A2] m [A2] l

[0097] wherein A2 is one or more vinyl aromatic hard blocks, B2 is one or more soft blocks, X is a free radical of a difunctional initiator, Y is a free radical of an m- or (m+l)-functional coupling agent, and m, n and l are natural numbers from 1 to 10.

[0098] Particularly preferred are linear styrene-butadiene block copolymers P2 of the general formula A2-B2-A2, which have one or more, preferably 1 to 5, more preferably 2 to 4, soft blocks B2 with a random styrene / butadiene distribution between two A2 blocks. These block copolymers can be obtained by anionic polymerization in nonpolar solvents with the addition of polar cosolvents or potassium salts, as described, for example, in WO 95 / 35335 or WO 97 / 40079 and WO 2010 / 072596.

[0099] The 1,2-vinyl content in the soft block B2 of the elastomeric block copolymer P2 is preferably less than 20% by weight, based on the total diene content, in particular in the range of 9 to 15% by weight, and particularly preferably in the range of 9 to 12% by weight. Suitable block copolymers P2 having such a 1,2-vinyl content in the soft block B2 are described in detail in WO 97 / 40079. In general, the vinyl content is the relative proportion of 1,2-bonds in the diene units, based on the sum of 1,2-, 1,4-cis-, and 1,4-trans-bonds.

[0100] In one embodiment, the elastomeric block copolymer P2 has the structure A2-(B2) n -A2, wherein the soft block consists of more than one soft block (B2) of different or identical composition, preferably identical composition n wherein n is a natural number of 2-10, preferably 2-5, more preferably 2-4.

[0101] In one embodiment, the elastomeric block copolymer P2 has the structure A2-(B2) n -A2-structured linear block copolymers, wherein the vinyl aromatic content of the soft blocks adjacent to the hard A2-blocks is lower than the vinyl aromatic content of the other soft blocks B2.

[0102] In a preferred embodiment, the elastomeric block copolymer P2 is a linear block copolymer of the general structure A2-B2-A2, having one or more soft blocks B2 located between two A2 blocks, the soft blocks B2 having a random vinyl aromatic monomer / diene distribution and a 1,2-vinyl content in the copolymer block P2 of less than 20% based on the total diene content.

[0103] Preferably, the elastomeric block copolymer P2 comprises (preferably consists of) 54 to 73 wt. %, preferably 60 to 70 wt. %, based on the weight of the total block copolymer P2, of a vinyl aromatic monomer, preferably styrene, and 27 to 46 wt. %, preferably 30-40 wt. %, based on the weight of the total block copolymer P2, of a diene monomer, preferably 1,3-butadiene.

[0104] Illustratively, the elastomeric block copolymer P2 can be obtained by anionic polymerization in a nonpolar solvent with addition of a polar cosolvent or preferably a potassium salt, as described, for example, in WO 96 / 20248 and WO 97 / 40079.

[0105] Additional non-elastic thermoplastic polymer P3

[0106] The polymer composition of the invention may comprise up to 20% by weight, preferably up to 10% by weight, based on the total polymer composition, of one or more further non-elastomeric thermoplastic polymers P3 different from P1 and P2.

[0107] According to the present invention, the sum of components P1 and P3 is equal to or greater than 75% by weight, preferably equal to or greater than 75.5% by weight, based on the total polymer composition. If the amount of component P1 is less than 80% by weight, based on the total composition, the polymer composition of the present invention comprises 5 to 20% by weight, preferably 6 to 20% by weight, more preferably 6 to 10% by weight, of component P3, based on the total polymer composition.

[0108] The further non-elastic thermoplastic polymer P3 may be any suitable non-elastic thermoplastic polymer, for example as described in WO 96 / 24634, such as polystyrene, polyamide, polyester, polyolefin, polyetherketone, polyoxyalkylene, polyarylene sulfide.

[0109] Exemplarily, the additional non-elastic thermoplastic polymer P3 is selected from styrene homopolymers and / or copolymers, polyamides, polyesters (e.g. polymethyl methacrylate, PMMA), polyolefins (e.g. polyethylene and polypropylene), polyetherketones, polyoxyalkylenes, polyarylene sulfides. Preferably, the additional non-elastic polymer P3 is selected from polystyrene (e.g. regular polystyrene, GPPS), styrene copolymers, polyamides, polyesters (e.g. polymethyl methacrylate, PMMA) and polyolefins (e.g. polyethylene and polypropylene).

[0110] In a preferred embodiment, the further non-elastic thermoplastic polymer P3 is selected from styrene homopolymers and / or copolymers, for example general purpose polystyrene (GPPS), high impact polystyrene (HIPS), (meth)acrylate-styrene copolymers, acrylonitrile-styrene copolymers (SAN), acrylonitrile-butadiene-styrene copolymers (ABS), acrylonitrile-styrene-acrylate copolymers (ASA), methacrylate-butadiene-styrene copolymers (MBS) and styrene-butadiene copolymers different from P1 and P2.

[0111] Preferably, the additional non-elastomeric thermoplastic polymer P3 may be chosen from styrene-butadiene copolymers different from P1 and P2, for example of the type or (a commercial product provided by INEOS Styrolution).

[0112] Preferably, the further non-elastic thermoplastic polymer P3 can be chosen from polyolefins, such as homopolymers and copolymers of ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 3-methyl-1-butene-1, 4-methyl-1-butene, 4-methyl-1-pentene and 1-octene. In particular, the polyolefin can be chosen from high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene or ethylene-propylene copolymers.

[0113] More preferably, said additional non-elastomeric thermoplastic polymer P3 is chosen from general purpose polystyrene (GPPS).

[0114] The preparation, structure and properties of general purpose polystyrene (GPPS) are described in detail in the literature (see "Plastics Handbook", Volume 4, "Polystyrene", published by Carl Hanser Verlag, 1996).

[0115] Preferably, the further non-elastic thermoplastic polymer P3 is selected from conventional polystyrene (GPPS) having a molecular weight MW in the range of 100,000 to 320,000 g / mol, preferably in the range of 120,000 to 220,000 g / mol. Typically, the polydispersity index D (Mw / Mn) of the conventional polystyrene used as P3 is in the range of 2 to 5, preferably 2.2 to 4.5. Typically, the molecular weight MW and the polydispersity index D are determined by gel permeation chromatography (GPC) according to ISO 16014-3:2012 (size exclusion at low temperature T<60°C, relative calibration method, polystyrene in THF as standard).

[0116] Preferably, the further non-elastic thermoplastic polymer P3 is selected from general purpose polystyrene (GPPS) having a melt volume flow rate (MVR), measured on the polymer melt at 200° C. and a load of 5 kg according to ISO 1133-1:2011, of 8 to 35 cm 3 / 10min, preferably 10 to 30cm 3 Preferably, the further non-elastic thermoplastic polymer P3 is selected from general purpose polystyrene (GPPS) having a Vicat temperature (Vicat B / 50), measured according to ISO 306:2004, in the range of 80 to 110° C., preferably 85 to 105° C.

[0117] Suitable conventional polystyrenes are prepared by anionic or free-radical polymerization processes. The inhomogeneity of the polymers, which can be influenced by the polymerization process, is of little importance here.

[0118] Preferably, the polymer composition comprises as component P3 0.5 to 20% by weight, preferably 1 to 10% by weight, more preferably 2 to 8% by weight, based on the total polymer composition, of one or more conventional polystyrenes.

[0119] In a preferred embodiment, if the amount of component P1 is less than 80% by weight, based on the total polymer composition, the polymer composition of the invention comprises, as component P3, from 6 to 20% by weight, preferably from 6 to 10% by weight, based on the total polymer composition, of one or more general-purpose polystyrenes.

[0120] Release agent C.

[0121] The polymer composition of the invention may comprise up to 1.5% by weight, preferably up to 0.15% by weight, more preferably up to 0.1% by weight, based on the total polymer composition, of one or more mold release additives C.

[0122] The mold release additive C can be selected from the mold release agents and lubricants generally known for use in styrene polymer compositions, in particular from the known waxes and oils.

[0123] Preferably, the release additive C is selected from long-chain fatty acids, such as stearic acid or behenic acid, fatty acid salts (such as calcium stearate or zinc stearate), fatty acid esters (such as stearic acid or pentaerythritol tetrastearate), amide fatty acid derivatives (such as ethylenebisstearamide, erucamide, ), phosphates (e.g. tricalcium phosphate), hydrocarbon waxes, such as microcrystalline wax and paraffin wax (e.g. ) and fumed silica (e.g. ). Usually fatty acids are straight or branched, saturated or unsaturated C5-C 25 Alkyl chain carboxylic acid.

[0124] More preferably, the release additive C is selected from stearic acid, stearates, stearic acid esters and stearamide. Most preferably, the at least one release agent C is selected from stearic acid and stearates, such as calcium stearate and zinc stearate.

[0125] In a preferred embodiment, the polymer composition comprises from 0.01 to 0.15% by weight, preferably from 0.02 to 0.10% by weight, based on the total polymer composition, of at least one mold release additive C, preferably selected from fatty acids, fatty acid esters, amide derivatives of fatty acids and hydrocarbon waxes, more preferably selected from stearic acid, stearates, stearic esters and stearamide.

[0126] Additional additives D

[0127] The polymer composition of the invention may comprise up to 10% by weight, preferably up to 5% by weight, based on the total polymer composition, of one or more additional additives D different from C. Preferably, the polymer composition may comprise 0.01 to 10% by weight, preferably 0.1 to 5, more preferably 0.1 to 2.5% by weight of one or more additives D.

[0128] The additional additives are typically selected from commonly known additives for styrene butadiene copolymers and compositions thereof.

[0129] The polymer composition may comprise, as component D, from 0.01 to 5% by weight of customary additives other than the release agents C, such as processing aids, stabilizers, oxidation inhibitors, UV absorbers, flame retardants, colorants, pigments and plasticizers.

[0130] Examples of oxidation inhibitors and heat stabilizers are sterically hindered phenols, their various substituents, and mixtures thereof, in concentrations up to 1 wt. %, based on the weight of the total polymer composition.

[0131] UV stabilizers which may be mentioned are various substituted resorcinols, salicylates, benzotriazoles and benzophenones, generally used in amounts of up to 2% by weight, based on the total polymer composition.

[0132] Preferably, stabilizers are used, in particular oxygen radical scavengers, e.g. 1010(BASF SE), 1010, 1076, 565 and mixtures thereof, carbon radical scavengers such as GS, GM and mixtures thereof, and / or auxiliary stabilizers, e.g. 168 (BASF SE). The stabilizers are all commercially available. The preferred amount of the stabilizers is 0.01 to 0.5 wt%, more preferably 0.1 to 0.3 wt%.

[0133] Examples of processing aids are homogeneously miscible oils or oil mixtures, in particular selected from mineral oils (medical grade mineral oils), plant oils (also known as vegetable oils) and silicone oils, which can be used in amounts of 0.1-5% by weight, preferably 0.5-3% by weight.

[0134] Preferably, the additive used as additional additive D in the polymer composition of the present invention does not scatter light in order to maintain the transparency of the polymer composition.

[0135] Method for preparing the polymer composition of the present invention

[0136] The present invention also relates to a process for preparing a polymer composition. In particular, the present invention relates to a process for preparing a polymer composition as described above, wherein components P1 and optionally P2, P3, C and / or D are melt compounded at a temperature in the range of 180 to 280°C, preferably 200 to 250°C.

[0137] The polymer composition of the present invention can be prepared by known methods. For example, an extruder, such as a co-rotating or counter-rotating single-screw or twin-screw extruder, or other conventional kneading equipment, such as a continuous or batch kneader, a Brabender mixer, or a Banbury mixer, can be used. The kneading equipment should ensure sufficient homogenization of the components, thereby ensuring micromixing.

[0138] The polymer compositions can be obtained by mixing and homogenizing the components by customary methods of plastics technology, wherein the order of addition of the components can vary.

[0139] Molded articles made from polymer compositions

[0140] Furthermore, the present invention relates to a molded article (shaped article) made from the above polymer composition. In particular, the molded article can be produced by a generally known injection molding method.

[0141] In particular, the moldings produced from the polymer compositions of the invention are medical devices, in particular transparent, elastic and flexible devices, such as containers, tubes, hoses or bags, for example for perfusion or transfusion systems, infusion apparatus, dialysis devices.

[0142] In a preferred embodiment, the present invention relates to a molded article made from the polymer composition of the present invention, wherein the molded article is a medical device, preferably a drip chamber.

[0143] In particular, the molded article, preferably a medical device, more preferably a drip chamber, exhibits one or more, preferably all, of the following properties:

[0144] - Melt volume flow (MVR), measured according to ISO 1133-1:2011 at 200°C and 5 kg load on polymer melt, 24 to 40 cm 3 / 10min, preferably 25 to 40cm 3 / 10min, more preferably 25 to 38cm 3 / 10min, preferably 25.2 to 38cm 3 / 10min, most preferably 25.2 to 35.2cm 3 / 10min;

[0145] - Shore D hardness, determined according to ASTM D2240 (measured after 15 seconds), in the range of 50 to 68, preferably in the range of 50 to 62, more preferably in the range of 55 to 62;

[0146] - an elastic modulus (E-modulus), measured according to ISO 527 (e.g. on a Zwick tensile testing machine with a 2.5 kN + 500 N load cell), of greater than 1000 MPa, preferably greater than 1020 MPa, more preferably greater than 1050 MPa, in particular greater than 1100 MPa;

[0147] - a Vicat temperature, Vicat A / 50 measured according to ISO 306:2004, exceeding 68°C, preferably exceeding 70°C, more preferably exceeding 73°C.

[0148] In a preferred embodiment, the molded article is a medical device, in particular a transparent, soft and flexible medical device.In a particularly preferred embodiment, the molded article of the present invention is a drip chamber.

[0149] Uses of polymer compositions

[0150] Furthermore, the present invention relates to the use of the polymer composition according to the invention for producing molded articles.The polymer composition according to the invention can advantageously be used for producing transparent, soft and flexible medical devices, such as medical tubes, medical hoses, medical bags, medical foils, catheters, balloons and drip chambers.

[0151] Preferably, the present invention relates to the use of the polymer composition of the present invention for the preparation of a molded article, wherein the molded article is a medical device, preferably a drip chamber. More preferably, the polymer composition of the present invention is optimized for the production of a drip chamber, in particular a drip chamber having one or more properties as defined above.

[0152] The present invention will be further described below with examples and claims: Example

[0153] 1. Test Method

[0154] a. Melt Volume Rate (MVR): MVR is measured according to ISO 1133-1:2011 on a polymer melt at 200°C and a 5 kg load.

[0155] b. Mechanical properties: Shore D, tensile test and Vicat test specimen preparation conditions: at 220 ° C, screw speed 500 mm / s, injection speed 100 mm / s, injection pressure 1500 bar and cooling time 50 s (25 ° C).

[0156] Subsequently, the samples were conditioned at 23°C for 24 hours.

[0157] Shore D hardness values ​​(measured after 15 seconds) are measured according to ASTM D2240 using a measuring column and an analog Shore D meter (supplied by BAQ GmbH, Germany). The measurements are performed on specimens with a minimum thickness of 6 mm (or two 3 mm specimens stacked on top of each other). The values ​​given are the average of 10 measurements.

[0158] Tensile tests (stress and strain at yield and break, and E modulus) were measured according to ISO 527 on a Zwick tensile testing machine (with a 2.5 kN + 500 N load cell). For this purpose, the specimens were prepared in the 1A configuration specified in the standard. The values ​​given are the average of at least five measurements.

[0159] Vicat temperature (Vicat A / 50) is measured using 1 kg conditions in accordance with ISO 306:2004.

[0160] c. Demolding behavior

[0161] The forming behavior of the 1A specimens used for tensile testing was evaluated during the production. The demolding behavior was described using numbers 1-4:

[0162] 1: Good demoulding

[0163] 2: Demolding is general

[0164] 3: Poor demoulding

[0165] 4: Poor demoulding

[0166] 2. Preparation of polymer compositions and samples

[0167] The following components were used:

[0168] Block copolymer P1:

[0169] P1: Star-shaped styrene-butadiene block copolymer P1, the content of butadiene in the total block copolymer is 25%, and the content of styrene is 75% (both based on the total amount of monomers), and the MVR (200℃ / 5kg) is 34cm 3 / 10min.

[0170] Block copolymer P1 was prepared as follows:

[0171] In a batch reactor (stainless steel reactor, stirred, 50m 3 ) was used as the initial feed, and 20000 L of cyclohexane at 40 ° C was used as the initial feed, and 20 m 3 3885 L of styrene (S1) was added at a rate of 1 / h. When 388 L of S1 had been added, 26.00 L of a 1.4 M sec-butyllithium solution (BuLi 1) was immediately added for initiation. The reaction was allowed to proceed under continuous stirring until monomer consumption was complete (determined by no further increase in the temperature of the reaction mixture). After complete consumption of the monomer, the polymerization mixture was cooled to a temperature below 60°C by reflux cooling.

[0172] Next, 114.40 L of a 1.4 M sec-butyllithium (BuLi 2) solution was added in one portion as the second initiator mixture.

[0173] In the next step, 2147 L of styrene (S2) were added again and the polymerization reaction was carried out under continuous stirring to complete the monomer consumption (determined by the temperature of the reaction mixture no longer rising). After complete consumption of the monomer, the polymerization mixture was cooled to a temperature below 50° C. by reflux cooling.

[0174] Then, 2951 L of butadiene (B1) were added and polymerization was carried out with continuous stirring to complete monomer consumption (determined by no further increase in the temperature of the reaction mixture).

[0175] Then, 10 minutes after the last complete consumption of monomer, 18.8L PL 5382 (epoxidized soybean oil, BASF) was heated to 85° C., added to the polymer solution as a coupling agent and allowed to react for 10 minutes while stirring.

[0176] The reaction mixture was stabilized by acidification with a stream of 0.05 phm* demineralized water and 0.36 phm CO2 and was continuously stirred using a static mixer with 0.15 phm GS, 0.20phm 1010 and 0.15 phm 168 for stabilization.

[0177] *phm=parts per hundred by weight, representing the weight percentage of the components (initiator, coupling agent, etc.) based on the total weight of the monomers)

[0178] Finally, the cyclohexane solvent was removed by flash evaporation, degassing extruder and underwater pelletization to obtain styrene-butadiene block copolymer pellets.

[0179] Elastic block copolymer P2:

[0180] P2: linear styrene-butadiene block copolymer P2, the butadiene content of the total block copolymer is 35% by weight, the styrene content is 65% by weight (both based on total monomers), and the MVR (200°C / 5kg) is 14 cm 3 / 10 minutes.

[0181] Block copolymer P2 was prepared as follows:

[0182] In a batch reactor (stainless steel reactor, stirred, 50m 3 ) was used as the initial feed, and 20500 L of cyclohexane at 40 ° C was used as the initial feed, and 20 m 3 1344 L of styrene (S1) was added at a rate of 1 / h. When 134 L of S1 had been added, 47.91 L of a 1.4 M sec-butyl lithium solution (BuLi 1) as an initiator and 6.23 L of a 5 wt% solution of potassium tert-butylate (in cyclohexane) as a randomizer were added in one go. The reaction was allowed to proceed under continuous stirring until monomer consumption was complete (determined by no further increase in the temperature of the reaction mixture). After complete consumption of the monomers, the polymerization mixture was cooled to a temperature below 65° C. by reflux cooling.

[0183] In the next step, 924 L of styrene (S2) and 1439 L of butadiene (B1) are added together and polymerization is carried out under continuous stirring to complete monomer consumption (determined by the fact that the temperature of the reaction mixture no longer increases). After complete consumption of the monomers, the polymerization mixture is cooled to a temperature below 48°C by reflux cooling.

[0184] In the next step, 1193 L of styrene (S3) and 1857 L of butadiene (B2) are added together and polymerization is carried out under continuous stirring to complete monomer consumption (determined by the fact that the temperature of the reaction mixture no longer increases). After complete consumption of the monomers, the polymerization mixture is cooled to a temperature below 65°C by reflux cooling.

[0185] In the next step, 655 L of styrene (S4) and 1020 L of butadiene (B3) are added together and polymerization is carried out under continuous stirring to complete monomer consumption (determined by the fact that the temperature of the reaction mixture no longer increases). After complete consumption of the monomers, the polymerization mixture is cooled to a temperature below 65°C by reflux cooling.

[0186] In the next step, 1344 L of styrene (S5) were added and polymerization was allowed to proceed with continuous stirring to complete monomer consumption (determined by no further increase in the temperature of the reaction mixture).

[0187] Then, 10 minutes after the last complete consumption of the monomer, 9.8 L of isopropyl alcohol was added to the polymer solution and reacted for 10 minutes under stirring.

[0188] Then, the mixture was heated to 0.06 phm* demineralized water and 0.43 phm CO 2 The reaction mixture was stabilized by gas flow acidification and the static mixer was used to continuously add 0.15 phm GS, 0.20phm 1010 and 0.15 phm 168 for stabilization.

[0189] *phm = "percentage by weight of components, initiators, coupling agents, etc., calculated based on the total weight of monomers).

[0190] Finally, the cyclohexane solvent was removed by flash evaporation, degassing extruder and underwater pelletization to obtain styrene-butadiene block copolymer pellets.

[0191] Other non-elastic thermoplastic polymers P3:

[0192] P3_I: ordinary polystyrene 124N (INEOS Styrolution, Germany), melt volume flow rate MVR is 12cm 3 / 10 min (200°C / 5 kg) and Vicat B / 50 was 87°C.

[0193] P3_II: ordinary polystyrene 156F (INEOS Styrolution, Germany), melt volume flow rate MVR is 28cm 3 / 10 min (200°C / 5 kg) and Vicat B / 50 is 101°C.

[0194] Additive C

[0195] C: Masterbatch containing 5% zinc stearate

[0196] The polymer compositions summarized in Table 1 were prepared by melt compounding in a twin-screw extruder at a temperature of 230°C.

[0197] Test specimens were prepared by injection molding as described above.

[0198]

[0199]

[0200] Notes to Table 1: Composition of the polymer compositions, values ​​are given in wt. % based on the total polymer composition, pph is calculated on the basis of zinc stearate and means parts of zinc stearate per hundred parts of P1+P2+P3.

[0201] 3. Results

[0202] The test results of the polymer compositions according to Test Examples 1 to 15 were obtained as described above.

[0203] The results are summarized in Table 2 (two parts).

[0204]

[0205] Table 2 Part 1

[0206]

[0207] Table 2 Part 2

[0208] The results show that the properties of the polymer composition of the present invention are within the target values ​​that are particularly required for the production of medical drip chambers.

[0209] It has been found that the desired balance of properties with respect to melt flow rate, thermal stability, hardness and elasticity can be achieved in a composition comprising 6 to 20 wt. % of component P3 if the amount of the defined block copolymer P1 is at least 65 wt. %, the sum of the non-elastomeric polymer components P1 and P3 is at least 75 wt. %, and if the amount of component P1 is less than 80 wt. %, such a composition achieves

[0210] The desired balance of properties can also be achieved in the resulting composition if the amount of the defined block copolymer P1 is at least 80% by weight, preferably at least 81% by weight, the amount of the elastomeric block copolymer P2 is at most 20% by weight, preferably at most 19% by weight, and the other components are within the defined ranges as required.

Claims

1. A polymer composition comprising the following components: P1. Based on the total polymer composition, 65 to 100% by weight of at least one block copolymer P1 comprising at least one vinyl aromatic monomer and at least one diene monomer, wherein the block copolymer P1 comprises 65 to 80 wt. %, based on the block copolymer P1, at least one hard block A1 comprising 90 to 100 wt. %, based on the total hard blocks A1, of vinyl aromatic monomers and 0 to 10 wt. %, based on the total hard blocks A1, of diene monomers, and 20 to 35 wt. %, based on the block copolymer P1, at least one soft block B1 comprising 0 to 10 wt. %, based on the total soft blocks B1, of vinyl aromatic monomers and 90 to 100 wt. %, based on the total soft blocks B1, of diene monomers; P2. 0 to 35 wt. % of at least one elastomeric block copolymer P2 comprising at least one vinyl aromatic monomer and at least one diene monomer, based on the total polymer composition, wherein the block copolymer P2 comprises 28 to 40 wt. %, based on the block copolymer P2, at least one hard block A2 comprising 90 to 100 wt. %, based on the total hard blocks A2, of vinyl aromatic monomers and 0 to 10 wt. %, based on the total hard blocks A2, of diene monomers, and 60 to 72% by weight, based on the block copolymer P2, at least one soft block B2 comprising 30 to 60% by weight, based on the total soft blocks B2, of vinyl aromatic monomers and 40 to 70% by weight, based on the total soft blocks B2, of diene monomers; P3. Based on the total polymer composition, 0 to 20% by weight of one or more additional non-elastic thermoplastic polymers P3; C. 0 to 1.5% by weight, based on the total polymer composition, of at least one mold release additive C; D. 0 to 10% by weight of one or more additional additives D, based on the total polymer composition, provided that the sum of components P1 and P3, based on the total polymer composition, is equal to or greater than 75% by weight; and provided that if the amount of component P1, based on the total polymer composition, is less than 80 wt. %, the polymer composition comprises, based on the total polymer composition, 5 to 20 wt. % of component P3, The polymer composition has a melt volume flow rate (MVR), measured on a polymer melt at 200° C. and a load of 5 kg according to ISO 1133-1:2011, of 24 to 40 cm 3 / 10min, and the melt volume flow rate (MVR) of the block copolymer P1, measured according to ISO 1133-1:2011 at 200°C and 5 kg load, is in the range of 30 to 40 cm 3 / min range.

2. The polymer composition according to claim 1, wherein the polymer composition comprises: P1. Based on the total polymer composition, 80 to 100% by weight of at least one block copolymer P1; P2. Based on the total polymer composition, 0 to 20% by weight of at least one elastomeric block copolymer P2; P3. Based on the total polymer composition, 0 to 20% by weight of one or more additional non-elastic thermoplastic polymers P3; C. 0 to 0.15% by weight, based on the total polymer composition, of at least one mold release additive C; D. 0 to 10% by weight of one or more additional additives D, based on the total polymer composition. 3 . The polymer composition according to claim 1 , wherein the block copolymer P1 comprises 20 to 30% by weight of diene monomers, based on the total block copolymer P1. 4 . The polymer composition according to claim 1 , wherein the glass transition temperature Tg of the hard block A1 of the block copolymer P1 is higher than 80° C., and the glass transition temperature Tg of the soft block B1 of the block copolymer P1 is lower than −60° C. 5 . The polymer composition according to claim 1 , wherein the elastomeric block copolymer P2 comprises 30 to 40 wt % of diene monomers, based on the total block copolymer P2. 6 . The polymer composition according to claim 1 , wherein the glass transition temperature Tg of the hard block A2 of the elastomeric block copolymer P2 is higher than 50° C., and the glass transition temperature Tg of the soft block B2 of the elastomeric block copolymer P2 is lower than 0° C.

7. The polymer composition according to claim 1 or 2, wherein the further non-elastomeric thermoplastic polymer P3 is selected from the group consisting of polystyrene, styrene copolymers, polyamides, polyesters and polyolefins.

8. The polymer composition according to claim 1 or 2, wherein the polymer composition comprises from 1 to 10% by weight of one or more additional non-elastic thermoplastic polymers P3 selected from conventional polystyrenes, based on the total polymer composition.

9. The polymer composition according to claim 1 or 2, wherein the polymer composition comprises 0.01 to 0.15% by weight, based on the total polymer composition, of at least one mold release additive C selected from stearic acid, stearates, stearic acid esters and stearic acid amides.

10. A method for preparing a polymer composition according to claim 1 or 2, wherein the components P1 and optionally P2, P3, C and / or D are melt mixed at a temperature in the range of 180 to 280°C.

11. A molded article made from a polymer composition comprising P1. 65 to 100% by weight, based on the total polymer composition, of at least one block copolymer P1 comprising at least one vinyl aromatic monomer and at least one diene monomer, the block copolymer P1 comprising: 65 to 80 wt. %, based on the block copolymer P1, of at least one hard block A1 comprising 90 to 100 wt. %, based on the total hard blocks A1, of vinyl aromatic monomers and 0 to 10 wt. %, based on the total hard blocks A1, of diene monomers, and 20 to 35% by weight, based on the block copolymer P1, of at least one soft block B1 comprising 0 to 10% by weight, based on the total soft blocks B1, of vinyl aromatic monomers and 90 to 100% by weight, based on the total soft blocks B1, of diene monomers; P2. 0 to 35 wt. % of at least one elastomeric block copolymer P2 comprising at least one vinyl aromatic monomer and at least one diene monomer, based on the total polymer composition, said block copolymer P2 comprising: 28 to 40 wt. %, based on the block copolymer P2, of at least one hard block A2 comprising 90 to 100 wt. %, based on the total hard blocks A2, of vinyl aromatic monomers and 0 to 10 wt. %, based on the total hard blocks A2, of diene monomers, and 60 to 72% by weight, based on the block copolymer P2, of at least one soft block B2 comprising 30 to 60% by weight, based on the total soft blocks B2, of vinyl aromatic monomers and 40 to 70% by weight, based on the total soft blocks B2, of diene monomers; P3. Based on the total polymer composition, 0 to 20% by weight of one or more additional non-elastic thermoplastic polymers P3; C. 0 to 1.5% by weight, based on the total polymer composition, of at least one mold release additive C; D. 0 to 10% by weight, based on the total polymer composition, of one or more additional additives D, Provided that the sum of components P1 and P3 is equal to or greater than 75% by weight, based on the total polymer composition; and provided that if the amount of component P1 is less than 80 wt. %, based on the total composition, the polymer composition comprises, based on the total polymer composition, 5 to 20 wt. % of component P3, The molded article is a medical device.

12. The molded article according to claim 11, wherein the molded article is a drip chamber.

13. A use for preparing a molded article using a polymer composition comprising P1. 65 to 100% by weight, based on the total polymer composition, of at least one block copolymer P1 comprising at least one vinyl aromatic monomer and at least one diene monomer, the block copolymer P1 comprising: 65 to 80 wt. %, based on the block copolymer P1, of at least one hard block A1 comprising 90 to 100 wt. %, based on the total hard blocks A1, of vinyl aromatic monomers and 0 to 10 wt. %, based on the total hard blocks A1, of diene monomers, and 20 to 35% by weight, based on the block copolymer P1, of at least one soft block B1 comprising 0 to 10% by weight, based on the total soft blocks B1, of vinyl aromatic monomers and 90 to 100% by weight, based on the total soft blocks B1, of diene monomers; P2. 0 to 35 wt. % of at least one elastomeric block copolymer P2 comprising at least one vinyl aromatic monomer and at least one diene monomer, based on the total polymer composition, said block copolymer P2 comprising: 28 to 40 wt. %, based on the block copolymer P2, of at least one hard block A2 comprising 90 to 100 wt. %, based on the total hard blocks A2, of vinyl aromatic monomers and 0 to 10 wt. %, based on the total hard blocks A2, of diene monomers, and 60 to 72% by weight, based on the block copolymer P2, of at least one soft block B2 comprising 30 to 60% by weight, based on the total soft blocks B2, of vinyl aromatic monomers and 40 to 70% by weight, based on the total soft blocks B2, of diene monomers; P3. Based on the total polymer composition, 0 to 20% by weight of one or more additional non-elastic thermoplastic polymers P3; C. 0 to 1.5% by weight, based on the total polymer composition, of at least one mold release additive C; D. 0 to 10% by weight, based on the total polymer composition, of one or more additional additives D, Provided that the sum of components P1 and P3 is equal to or greater than 75% by weight, based on the total polymer composition; and provided that if the amount of component P1 is less than 80 wt. %, based on the total composition, the polymer composition comprises, based on the total polymer composition, 5 to 20 wt. % of component P3, Wherein, the molded product is a medical device.

14. The use according to claim 13, wherein the molded article is a drip chamber.

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