Biodegradable polymer fibers made from renewable raw materials

Abstract

The invention relates to a biodegradable polymer fiber made of renewable raw materials and having good physical properties, a preparation method thereof and use thereof.

Description

Technical Field

[0001] The invention relates to a biodegradable polymer fiber made of renewable raw materials and having good physical properties, a preparation method thereof and use thereof. Background Art

[0002] Polymer fibers, i.e. fibers based on synthetic polymers, are produced on a large scale in industry. Here, the synthetic polymers serving as the basis are processed by a melt spinning process. For this purpose, the thermoplastic polymer material is melted and introduced into a spinning bundle in a liquid state through an extruder. The molten material is fed from the spinning bundle into a so-called spinning nozzle. The spinning nozzle usually has a spinneret with a plurality of holes, from which the individual capillaries (filaments) of the fibers are extruded. In addition to the melt spinning process, wet or solvent spinning processes are also used to produce spun fibers. Here, instead of a melt, a high-viscosity solution of a synthetic polymer is extruded through a nozzle with fine holes. Those skilled in the art refer to these two processes as so-called multi-point spinning processes.

[0003] The polymer fibers produced in this way are used for textile and / or technical applications. It is advantageous here that the polymer fibers have good dispersibility in aqueous systems, for example in the production of wet-laid nonwovens. It is also advantageous for textile applications if the polymer fibers have good mechanical strength, for example in order to function well in fiber post-processing, for example in stretching on conveyor lines. It is also advantageous for textile applications if the polymer fibers, in particular in the form of nonwovens, have low thermal shrinkage.

[0004] The modification or finishing of polymer fibers for the respective end use or necessary intermediate processing steps, such as drawing and / or crimping, is generally carried out by applying suitable finishes or sizing agents, which are applied to the surface of the finished or to be treated polymer fibers.

[0005] Another possibility is to chemically modify the polymer backbone itself, for example by introducing flame-retardant compounds into the polymer main chain and / or into the side chains.

[0006] Furthermore, additives such as antistatic agents or color pigments can be introduced into the molten thermoplastic polymer or into the polymer fibers during the multipoint spinning process.

[0007] The dispersion behavior of polymer fibers is influenced, among other things, by the nature of the synthetic polymer. In particular in the case of fibers made of thermoplastic polymers, the dispersibility in aqueous systems is therefore influenced and adjusted by the finish or sizing agent applied to the surface.

[0008] Recently, efforts have been made to find fiber systems that, on the one hand, meet the above requirements and are made from renewable raw materials, and on the other hand, require as little or no changes as possible in subsequent applications so that existing processes and facilities can continue to be used. Summary of the invention

[0009] Therefore, there is an object to provide polymer fibers made from renewable raw materials which, on the one hand, should have good physical properties so that good fiber post-processing, such as drawing on a conveyor line, is possible, and which also have low thermal shrinkage and, on the other hand, are biodegradable. Furthermore, it is advantageous if polymer fibers made from renewable raw materials have good dispersibility, in particular long-term dispersibility, which remains even after long storage periods.

[0010] The above-mentioned object is achieved by a two-component polymer fiber according to the present invention, wherein the fiber comprises component A (core) and component B (sheath), the melting point of the thermoplastic polymer in component A is at least 5°C higher than the melting point of the thermoplastic polymer in component B, and the fiber material forming component A has biopolymer A and the fiber material forming component B has biopolymer B.

[0011] The bicomponent polymer fibers according to the invention are usually stored in the form of tows after the spinning process, and then stretched and post-processed on a conveyor line by specific methods. The tows can also be processed further directly, and the loading of the tows into so-called tanks can be completely or partially omitted.

[0012] The combination of specific biopolymers, ie component A (core) and component B (sheath), in combination with specific stretching, leads to bicomponent polymer fibers according to the invention which also have low thermal shrinkage.

[0013] polymer

[0014] The polymers used according to the invention are thermoplastic polycondensates based on so-called biopolymers.

[0015] In the present invention, the term "thermoplastic polymer" means a plastic that can be deformed (thermoplastically) within a certain temperature range, preferably within the range of 25° C. to 350° C. This process is reversible, i.e. it can be repeated as many times as desired by cooling and heating again to the molten state, as long as the so-called thermal decomposition of the material does not start due to overheating. This is what distinguishes thermoplastic polymers from thermosetting plastics and elastomers.

[0016] Among the thermoplastic polycondensates based on so-called biopolymers, synthetic biopolymers, in particular melt-spinnable synthetic biopolymers, are particularly preferred.

[0017] In the present invention, the term "synthetic biopolymer" refers to a material composed of biological raw materials (renewable raw materials). This is different from traditional petroleum-based materials or plastics such as polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC).

[0018] The bicomponent fibers according to the present invention are produced from biodegradable synthetic biopolymers, wherein the term biodegradable is defined, for example, in accordance with ASTM D5338-15 (Standard Test Method for Determining Aerobic Biodegradation of Plastic Materials Under Controlled Composting Conditions, Incorporating Thermophilic Temperatures, ASTM International, West Conshohocken, PA, 2015, www.astm.org )Sure.

[0019] Biopolymer A (core)

[0020] The synthetic biopolymer A forming component A is an aliphatic polyester, in particular a biopolymer comprising repeating units of lactic acid, hydroxybutyric acid and / or glycolic acid, preferably lactic acid and / or glycolic acid, in particular lactic acid. Polylactic acid is particularly preferred here.

[0021] Aliphatic polyesters refer to those polyesters that generally have at least about 50 mole percent aliphatic monomers, preferably at least about 60 mole percent in some embodiments, and at least about 70 mole percent in particularly preferred embodiments.

[0022] "Polylactic acid" refers here to a polymer consisting of lactic acid units. Such polylactic acid is usually produced by condensation of lactic acid, but can also be obtained by ring-opening polymerization of lactide under appropriate conditions.

[0023] Particularly suitable polylactic acids according to the invention include poly(glycolide-co-L-lactide), poly(L-lactide), poly(L-lactide-co-s-caprolactone), poly(L-lactide-co-glycolide), poly(L-lactide-co-D,L-lactide), poly(D,L-lactide-co-glycolide) and poly(dioxanone). Such polymers are available, for example, from Boehringer IngelheimPharma KG (Germany) under the trade name GL 903, L 206 S, L207 S, L 209 S, L 210, L 210 S, LC 703S, LG 824 S, LG 855 S, LG 857 S, LR 704S, LR 706 S, LR 708, LR 927 S, RG 509 S and X 206 S commercially available.

[0024] Polylactic acids which are particularly advantageous for the purposes of the present invention are, in particular, poly-D-lactic acid, poly-L-lactic acid or poly-D,L-lactic acid.

[0025] The term "polylactic acid" generally refers to homopolymers of lactic acid, such as poly (L-lactic acid), poly (D-lactic acid), poly (DL-lactic acid), mixtures thereof, and copolymers containing lactic acid as the main component and a small amount (preferably less than 10 mol %) of a copolymerizable comonomer.

[0026] Other suitable materials for biopolymer A are copolymers or terpolymers based on polylactic acid, polyglycolic acid, polyalkylene carbonates (e.g. polyethylene carbonate), polyhydroxyalkanoates (PHA), polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV) and polyhydroxybutyrate-hydroxyvalerate copolymers (PHBV).

[0027] In a particularly preferred embodiment, the biopolymer A is exclusively a thermoplastic polycondensate based on lactic acid.

[0028] The polylactic acid used according to the present invention has at least 500g / mol, preferably at least 1000g / mol, particularly preferably at least 5000g / mol, suitably at least 10,000g / mol, particularly at least 25,000g / mol number average molecular weight (Mn), preferably by gel permeation chromatography for narrow distribution polystyrene standards or by end group titration.On the other hand, the number average molecular weight is preferably at most 1,000,000g / mol, suitably at most 500,000g / mol, advantageously at most 100,000g / mol, particularly at most 50,000g / mol.It has been proven that the number average molecular weight in the range of at least 10,000g / mol to 500,000g / mol is particularly useful in the present invention.

[0029] Preferred lactic acid polymers, in particular poly-D-lactic acid, poly-L-lactic acid or poly-D,L-lactic acid, preferably have a weight-average molecular weight (Mw) in the range of 750 g / mol to 5,000,000 g / mol, preferably in the range of 5,000 g / mol to 1,000,000 g / mol, particularly preferably in the range of 10,000 g / mol to 500,000 g / mol, in particular in the range of 30,000 g / mol to 500,000 g / mol, preferably determined by gel permeation chromatography against narrow distribution polystyrene standards, and the polydispersity of these polymers is advantageously in the range of 1.5 to 5.

[0030] Particularly suitable lactic acid polymers, in particular poly-D-lactic acid, poly-L-lactic acid or poly-D,L-lactic acid, have an intrinsic viscosity, measured in chloroform at 25° C. and 0.1% polymer concentration, in the range of 0.5 dl / g to 8.0 dl / g, preferably in the range of 0.8 dl / g to 7.0 dl / g, in particular in the range of 1.5 dl / g to 3.2 dl / g.

[0031] Furthermore, within the scope of the present invention, biopolymers, in particular thermoplastic synthetic biopolymers, are very advantageous, having a glass transition temperature of more than 20° C., advantageously more than 25° C., preferably more than 30° C., particularly preferably more than 35° C., in particular more than 40° C. In a very particularly preferred embodiment of the present invention, the glass transition temperature of the polymer is in the range of 35° C. to 55° C., in particular in the range of 40° C. to 50° C.

[0032] Furthermore, polymers having a melting temperature of greater than 120°C, advantageously at least 130°C, preferably greater than 150°C and at most 250°C, particularly preferably at most 210°C, particularly preferably in the range of 120°C to 250°C, in particular in the range of 150°C to 210°C are particularly suitable.

[0033] The glass transition temperature and melting point of the polymers are preferably determined by dynamic differential scanning calorimetry (DSC). The following procedure has proven to be particularly useful in this regard:

[0034] Biopolymer B(skin)

[0035] The synthetic biopolymer B forming component B is preferably a biopolymer having a melting point at least 5° C. lower than the synthetic biopolymer A forming component A. Preferably, the melting point of biopolymer A is at least 10° C. higher than the melting point of synthetic biopolymer B, preferably at least 20° C., particularly preferably at least 30° C., in particular at least 40° C.

[0036] Biopolymer B is an aliphatic polyester, in particular an aliphatic polyester having repeating units that differ from the repeating units of biopolymer A in chemical structure.

[0037] Aliphatic polyesters refer to those polyesters that generally have at least about 50 mole percent, preferably in some embodiments at least about 60 mole percent, and in particularly preferred embodiments at least about 70 mole percent aliphatic monomers.

[0038] The number average molecular weight (Mn) of the biopolymer B is generally at least 10,000 Daltons, in particular at least 12,000 Daltons, particularly preferably at least 12500 Daltons and at most 120,000 Daltons, in particular at most 100,000 Daltons, particularly preferably at most 80,000 Daltons. The number average molecular weight (Mn) is generally determined by gel permeation chromatography against narrow distribution polystyrene standards.

[0039] Biopolymer B generally has a weight average molecular weight (Mw) of at least 50,000 daltons and at most 240,000 daltons, in particular at most 190,000 daltons, particularly preferably at most 100,000 daltons. The number average molecular weight (Mn) is generally determined by gel permeation chromatography against narrow distribution polystyrene standards.

[0040] According to ASTM test method D1238-13 (ASTM D1238-13, Standard Test Method for MeltFlow Rates of Thermoplastics by Extrusion Plastometer, ASTM International, West Conshohocken, PA, 2013, www.astm.org), the melt flow index of biopolymer B is generally 5 to 200 g / 10 min, in particular 15 to 160 g / 10 min, and particularly preferably 20 to 120 g / 10 min. The melt flow index is the weight (in grams) that a polymer can be pressed out through an extrusion rheometer orifice (0.0825 inch diameter) when subjected to a force of 2160 g at 190° C. for 10 minutes.

[0041] Biopolymer B was heated to 160 °C for 1000 s -1 The apparent viscosity, measured at a shear rate of 1.37° (s = seconds), is preferably in the range of 50 to 215 Pa*s (Pascal seconds), particularly preferably in the range of 70 to 200 Pa*s. It should be noted here that, on the one hand, a biopolymer B based on aliphatic polyester having too high an apparent viscosity is generally difficult to process, and, on the other hand, too low an apparent viscosity generally leads to extruded fibers without any tensile strength and insufficient bonding capacity (thermal bonding).

[0042] Furthermore, the biopolymer B is particularly suitable for having a melting temperature of greater than 50°C, advantageously at least 100°C, preferably greater than 120°C and at most 180°C, particularly preferably at most 160°C, and particularly preferably in the range of 50°C to 160°C, in particular in the range of 120°C to 160°C.

[0043] The glass transition temperature of biopolymer B is preferably at least 5° C., in particular at least 10° C., very particularly preferably at least 15° C. lower than the glass transition temperature of biopolymer A. The glass transition temperature is determined by DSC.

[0044] Examples of biopolymers B that may have a low melting point and a low glass transition temperature are aliphatic polyesters having repeating units of at least 5 carbon atoms (e.g., polyhydroxyvalerate, polyhydroxybutyrate-hydroxyvalerate copolymers and polycaprolactone), and aliphatic polymers based on succinate (e.g., polybutylene succinate, polybutylene succinate adipate and polyethylene succinate). More specific examples may include polyethylene oxalate, polyethylene malonate, polyethylene succinate, polypropylene oxalate, polypropylene malonate, polypropylene succinate, polybutylene oxalate, polybutylene malonate, polybutylene succinate and mixtures and copolymers of these compounds. Such aliphatic polyesters are known in principle (WO 2007 / 070064) and are usually synthesized by polycondensation of polyols and aliphatic dicarboxylic acids or their anhydrides.

[0045] In the present invention, polybutylene succinate and butylene succinate copolymers are particularly preferred.

[0046] Biopolymers B with high melting enthalpy and crystallization enthalpy levels are particularly suitable for thermal bonding. Typically, biopolymer B is selected to have a crystallinity or a melting latent heat (Delta Hf) greater than about 25 joules / gram ("J / g"), particularly preferably greater than 35 J / g, and especially greater than 50 J / g. The melting latent heat (ΔHf), crystallization latent heat (ΔHC) and crystallization temperature are determined according to ASTM D-3418 (ASTM D3418-15, Standard Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential Scanning Calorimetry, ASTM International, West Conshohocken, PA, 2015, www.astm.org ) was determined by differential scanning calorimetry ("DSC").

[0047] In addition to the above-mentioned biopolymer B, specific stretching according to the parameter set defined in accordance with the present invention enables the use of cheaper biopolymer B variants, wherein the bicomponent polymer fibers obtained thereby have a low thermal shrinkage. Therefore, these specific stretching parameters enable the use of more widely available biopolymers B. The number average molecular weight (Mn) of the specific biopolymer B used in this embodiment of the present invention is at least 10,000 Daltons, in particular at least 12,000 Daltons, more preferably at least 12,500 Daltons and at most 30,000 Daltons, in particular at most 28,000 Daltons, particularly preferably at most 25,000 Daltons. The number average molecular weight (Mn) is usually determined by gel permeation chromatography against narrow distribution polystyrene standards.

[0048] The melting temperature of the specific biopolymer B is greater than 50°C, advantageously at least 100°C, preferably greater than 120°C and at most 180°C, particularly preferably at most 160°C and particularly preferably in the range of 50°C to 160°C, in particular in the range of 120°C to 160°C.

[0049] The glass transition temperature of the specific biopolymer B is preferably at least 5° C., in particular at least 10° C., very particularly preferably at least 15° C. lower than the glass transition temperature of the biopolymer A. The glass transition temperature is determined by DSC.

[0050] Examples of specific biopolymers B that may have a low melting point and a low glass transition temperature are aliphatic polyesters having repeating units of at least 5 carbon atoms (e.g., polyhydroxyvalerate, polyhydroxybutyrate-hydroxyvalerate copolymer, and polycaprolactone), and aliphatic polymers based on succinate (e.g., polybutylene succinate, polybutylene succinate adipate, and polyethylene succinate). More specific examples may include polyethylene oxalate, polyethylene malonate, polyethylene succinate, polypropylene oxalate, polypropylene malonate, polypropylene succinate, polybutylene oxalate, polybutylene malonate, polybutylene succinate, and mixtures and copolymers of these compounds.

[0051] In the present invention, polybutylene succinate and butylene succinate copolymers are particularly preferred as the specific biopolymer B.

[0052] The specific biopolymer B with high melting enthalpy and crystallization enthalpy levels is particularly suitable for thermal bonding. Typically, the biopolymer B is selected to have a crystallinity or a melting latent heat (Delta Hf) greater than about 25 joules / gram ("J / g"), particularly preferably greater than 35J / g, especially greater than 50J / g. Latent heat of melting (ΔHf), latent heat of crystallization (ΔHC) and crystallization temperature are measured by differential scanning calorimetry ("DSC") according to ASTM D-3418 (ASTM D3418-15, Standard Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential Scanning Calorimetry, ASTM International, West Conshohocken, PA, 2015, www.astm.org).

[0053] The specific biopolymer B at 190°C ( Melt viscosity measured at 200s -1 (shear) is 250 to 400Pa*s, at 1200s -1 (shear) is 125 to 190 Pa*s, preferably 200s -1 (shear) is in the range of 260 to 380 Pa*s and within 1200s -1 (shear) in the range of 130 to 180 Pa*s, especially at 200s -1 (shear) in the range of 275 to 375 Pa*s and at 1200s -1 (shear) is in the range of 135 to 175 Pa*s.

[0054] Additives in Biopolymers A and B

[0055] The above-mentioned biopolymers A and B have conventional additives, such as antioxidants etc. It has been shown here that additives from the group of antioxidants are indispensable for the production and post-processing of the fibers, since the above-mentioned biopolymers A and B have a susceptibility to oxidative degradation.

[0056] Other common additives are pigments, stabilizers, surfactants, waxes, flow promoters, solid solvents, plasticizers and other materials, such as nucleating agents, which are added to improve the processing properties of the thermoplastic composition.

[0057] Due to the described properties, the above-mentioned biopolymer B, especially the specific biopolymer B, is sufficient even with reduced addition of additives, especially nucleating agents. Such nucleating agents, which are usually added, promote crystallization during the quenching of the fiber, thereby promoting its processing. One class of such nucleating agents is polycarboxylic acids, such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and mixtures of these acids, as described in U.S. Pat. No. 6,177,193. The nucleating agent is usually present in the biopolymer B in an amount of less than about 0.5% by weight, in some embodiments less than about 0.25% by weight, and in some embodiments less than about 0.1% by weight.

[0058] The bicomponent fibers according to the invention consist of at least 90% by weight of the above-mentioned aliphatic polyester biopolymers A and B and generally have less than about 10% by weight, preferably less than about 8% by weight, and particularly preferably less than about 5% by weight of additives in the biopolymer B forming the sheath.

[0059] As mentioned previously, due to the sensitivity of the above mentioned biopolymers to oxidative degradation, they require the addition of antioxidants, especially biopolymer B (skin).

[0060] Due to the chosen combination of raw materials and post-treatment, the amount of antioxidant used can be significantly reduced, ie the antioxidant content in the biopolymer B (skin) is between 0.025% and 0.2% by weight.

[0061] After spinning, the bicomponent fibers according to the invention are combined into tows and post-processed in a conveyor line using methods known in principle, in particular stretched and possibly also crimped or texturized. The above-mentioned specific biopolymers B can be used in particular by selecting specific conveyor line parameters during the stretching process.

[0062] Polymer Fiber

[0063] The bicomponent fibers according to the present invention can be in the form of finite fibers, such as so-called staple fibers, or in the form of endless fibers (filaments). For better dispersibility, the fibers are preferably in the form of staple fibers. The length of the above-mentioned staple fibers is not limited in principle, generally 2 to 200 mm, preferably 3 to 120 mm, and particularly preferably 4 to 60 mm.

[0064] The single titer of the bicomponent fibers, preferably staple fibers, according to the invention is 0.5 to 30 dtex, preferably 0.7 to 13 dtex. For some applications, a titer of 0.5 to 3 dtex and a fiber length of <10 mm, in particular <8 mm, particularly preferably <6 mm, particularly preferably <5 mm are particularly suitable.

[0065] The bicomponent fibers according to the invention exhibit low dry heat shrinkages in the range of 0% to 10%, preferably >0% to 8%, respectively measured at 110°C.

[0066] The combination of certain biopolymers according to the invention, i.e. component A (core) and a specific biopolymer B as component B (sheath), combined with a specific stretching enables the stretching force to be transferred to the core material as well, thereby achieving stretch-induced crystallization. This results in the above-mentioned low thermal shrinkage in the bicomponent polymer fiber according to the invention.

[0067] The production of the polymer fiber according to the invention is carried out in principle by conventional methods. First, the polymer is dried, if necessary, and fed into an extruder. The molten material is then spun by conventional means with corresponding nozzles. The outlet speed of the nozzle outlet face is matched to the spinning speed, thereby producing fibers with the desired fineness. The spinning speed refers to the speed at which the coagulation line is drawn.

[0068] The fibers formed may have circular, oval, and other suitable cross-sectional or other shapes.

[0069] The fiber filaments produced in this way are combined into yarns, which in turn are combined into tows. The tows are first stored in tanks for further processing. The tows temporarily stored in the tanks are taken out and large spun fiber bundles are produced.

[0070] Another subject of the invention is the post-treatment of the spun fiber bundles produced by the known method, which usually have a weight of 10 to 600 ktex, using conventional conveyor lines by specific stretching. The feed speed of the spun fiber bundle into the stretching or stretching device is preferably 10 to 110 m / min (feed speed). It is also possible to apply agents that promote stretching but do not adversely affect the subsequent properties.

[0071] Stretching may be performed in one stage or optionally using a two-stage stretching process (see, for example, US Pat. No. 3,816,486). One or more finishes may be applied prior to and during stretching using conventional methods.

[0072] The drawing according to the invention is carried out with a drawing ratio between 1.2 and 6.0, preferably between 2.0 and 4.0, in particular when using specific biopolymers B, wherein the temperature during the drawing of the tow is between 30° C. and 80° C. Thus, the drawing takes place in the glass transition temperature range of the tow to be drawn. The drawing according to the invention is carried out in the presence of steam, i.e. in a so-called steam box, so that the drawing point of the fiber is set in the steam box. The steam box is usually operated at a pressure of 3 bar.

[0073] By stretching in the presence of steam within the above-mentioned temperature range, the thermal shrinkage of the fibers can be reduced and adjusted in a targeted and controlled manner.

[0074] The conveyor line is preferably set up as follows:

[0075] The drawing is carried out in one stage in the steam box between the drawing unit S2 and the drawing unit S1, i.e. the drawing point of the fiber is located in the steam box. The temperature of all the godet wheels of S1 (usually 7) is 30-80°C. The entire drawing is carried out in the steam box. The steam box is preferably operated with 3 bar steam.

[0076] All the godet wheels (usually 7) of the subsequent stretching mechanism S2 are cold, and cold means room temperature (about 20-35° C.).

[0077] This so-called "cold drawing" way results in the drawing not being fixed on the S2 under tension at high temperatures. The advantage of cold S2 is that there is no risk of individual fibers sticking to the hot godet of the S2.

[0078] Despite being "cold-stretched", the fibers are not sensitive to high temperatures during tension-free setting in an oven and can withstand temperatures up to 100°C without sticking.

[0079] The above-mentioned "cold stretching" is particularly applicable to polybutylene succinate (FZ71), the melt viscosity of which is determined at a temperature of 190°C ( Rheo-Tester 1000) for 200s -1 (shear) in the range of 250 to 325 Pa*s and at 1200s -1 (shear) in the range of 125 to 150 Pa*s, preferably 200s -1 (shear) in the range of 260 to 300 Pa*s and at 1200s -1 (shear) in the range of 130 to 150 Pa*s, especially at 200s -1 (shear) in the range of 270 to 290 Pa*s and at 1200s -1 (shear) is in the range of 135 to 145 Pa*s.

[0080] As long as polybutylene succinate (FZ91) is determined at 190°C ( The melt viscosity of the Rheo-Tester 1000 is 200s -1 (shear) in the range of 340 to 400 Pa*s and at 1200s -1 (shear) in the range of 150 to 190 Pa*s, preferably 200 s -1(shear) in the range of 350 to 390 Pa*s and at 1200s -1 (shear) in the range of 160 to 185 Pa*s, especially at 200s -1 (shear) in the range of 360 to 385 Pa*s and at 1200s -1 If the (shear) is in the range of 165 to 180 Pa*s, the stretching device S2 is operated at a temperature in the range of 60°C to 100°C, that is, all the godet wheels (usually 7) have the above temperature.

[0081] The tow preferably has a density of 240 to 360 ktex before drawing.

[0082] For the possible crimping / texturing of the drawn fibers, conventional methods of mechanical crimping using crimping machines known per se can be applied. Preferred are steam-assisted mechanical devices for fiber crimping, such as stuffer boxes. However, fibers crimped by other methods, such as three-dimensionally crimped fibers, can also be used. For crimping, the tow is usually first heated to a temperature of 50° to 100° C., preferably 70° to 85° C., particularly preferably to about 78° C., and treated under conditions of a pressure of 1.0 to 6.0 bar, particularly preferably about 2.0 bar, on the tow feed rollers, a pressure of 0.5 to 6.0 bar, particularly preferably 1.5 to 3.0 bar, and 1.0 to 2.0 kg / min, particularly preferably 1.5 kg / min, of steam.

[0083] As long as the smooth or possibly curly fibers are relaxed and / or fixed in the oven or in the process air stream, this likewise takes place at temperatures of up to 130° C.

[0084] To prepare staple fibers, smooth or possibly curly fibers are picked up, then cut and optionally fluffed and stored in compressed bundles as flocking. The staple fibers of the invention are preferably cut on a mechanical cutting device after relaxation. To prepare tow types, cutting can be omitted. These tow types are stored in uncut form in bundles and pressed.

[0085] If the fibers according to the invention are in crimped form, the crimp is preferably at least 2 crimps (crimps) / cm, preferably at least 3 crimps (crimps) / cm, preferably at least 3 crimps / cm to 9.8 crimps / cm, particularly preferably 3.9 crimps / cm to 8.9 crimps / cm. For applications in the production of textile fabrics, a crimp of about 5 to 5.5 crimps per centimeter is particularly preferred. For the production of textile fabrics by a wet-laid process, the crimp must be set separately.

[0086] A textile fabric can be produced from the fibers according to the invention, which is also the subject of the present invention. Due to the good dispersibility of the fibers according to the invention, such a textile fabric is preferably produced by a wet-laid process.

[0087] The term "textile fabric" is therefore to be understood in its broadest sense within the scope of this specification. This may be any composition comprising the fibers according to the invention, which has been produced according to a fabric forming technology. Examples of such textile fabrics are nonwovens, in particular wet-laid nonwovens, preferably based on staple fibers, which are produced by thermal bonding.

[0088] The fibers according to the invention also have a good dispersibility durability, i.e. the fibers have very good dispersibility even after long-term storage in the form of bundles or similar structures, e.g. weeks or months. In addition, the fibers according to the invention have a good long-term dispersibility, i.e. when the fibers are dispersed in a liquid medium, e.g. water, the fibers remain dispersed for a longer time and start to settle only after a long time.

[0089] Test method:

[0090] Unless otherwise stated in the above description, the following measurement or test methods are used:

[0091] Denier:

[0092] The titer was determined according to DIN EN ISO 1973.

[0093] Dispersibility:

[0094] To assess the dispersibility, the following test method was developed and used according to the invention:

[0095] The fibers according to the invention are cut into lengths of 2 to 12 mm. The cut fibers are placed in a glass container (dimensions: length 150 mm; width 200 mm; height 200 mm) filled with deionized water (VE water; VE = completely desalinated) at room temperature (25° C.). The amount of fiber is 0.25 g per liter of deionized water. For better evaluation, 1 g of fiber and 4 liters of deionized water are usually used.

[0096] The fiber / VE water mixture was then stirred for at least three minutes (speed in the range of 750-1500 rpm) using a conventional laboratory magnetic stirrer (eg IKAMAG RCT) and a magnetic fish (80 mm), and then the stirrer was turned off. It was then assessed whether all the fibers were dispersed.

[0097] The dispersion behavior of the fibers was evaluated as follows:

[0098] Not dispersed (-)

[0099] Partial dispersion (o)

[0100] Completely dispersed (+)

[0101] The above evaluations are performed at defined time intervals.

[0102] Biodegradability

[0103] Measured according to ASTM D5338-15 (Standard Test Method for Determining AerobicBiodegradation of Plastic Materials Under Controlled Composting Conditions, Incorporating Thermophilic Temperatures, ASTM International, West Conshohocken, PA, 2015, www.astm.org).

[0104] Number average molecular weight (Mn)

[0105] Determined by gel permeation chromatography against narrow distribution polystyrene standards or by end group titration

[0106] Weight average molecular weight (Mw)

[0107] Determined by gel permeation chromatography against narrow distribution polystyrene standards or by end group titration

[0108] Intrinsic viscosity

[0109] Determined by GPC at 25°C at 0.1% polymer concentration in chloroform.

[0110] Glass transition temperature and melting temperature

[0111] The determination was performed by dynamic differential scanning calorimetry (DSC), and the steps were as follows:

[0112] DSC measurements were performed under nitrogen and calibrated against indium.

[0113] The nitrogen flow rate was 50 ml / min; the fiber weight was in the range of 2 to 3 mg.

[0114] The temperature range was from -50°C to 210°C at 10K / min, followed by isothermal heating for 5 min, and finally back to -50°C at 10K / min.

[0115] In general, the final temperature is always about 50°C higher than the expected highest melting point.

[0116] DSC measurements were performed by TA / Waters model Q100.

[0117] Melt viscosity

[0118] pass Rheo-Tester 1000 at 190°C, 200 s -1 (cut) and 1200s -1 The melt viscosity was measured under shear.

[0119] Apparent viscosity

[0120] The assay was performed following the guidance in WO 200 / / 070064.

[0121] Melt flow index

[0122] The melt flow index is measured according to ASTM test method D1238-13 (ASTM D1238-13, Standard Test Method for Melt Flow Rates of Thermoplastics by Extrusion Plastometer, ASTM International, West Conshohocken, PA, 2013, www.astm.org). The melt flow index is the weight (in grams) that a polymer can be forced out through an extrusion rheometer orifice (0.0825 inch diameter) when subjected to a force of 2160 grams for 10 minutes at 190°C.

[0123] Latent heat of fusion

[0124] The latent heat of fusion (ΔHf), latent heat of crystallization (ΔHC) and crystallization temperature were determined according to ASTM D-3418 (ASTM D3418-15, Standard Test Method for Transition Temperatures and Enthalpies of Fusion and Crystallization of Polymers by Differential Scanning Calorimetry, ASTM International, West Conshohocken, PA, 2015, www.astm.org ) was determined by differential scanning calorimetry (DSC).

[0125] Heat shrink

[0126] 12 fibers (measurement samples) were prepared from a tow band sample. They were clamped in a multi-clamp at one end with the aid of tweezers and a decurling weight was fixed at the other end. The measurement was performed using a PLA / PBS type (core / sheath) bicomponent fiber with a fineness of 2.2 dtex and a decurling weight of 190 mg.

[0127] The multi-clamp with the measuring sample is fixed to the tripod so that the measuring sample hangs freely on the tripod under prestress. The selected initial length (usually 150 mm) is marked on each fiber. This is done with the help of a marking line on the tripod and a marking point applied to the measuring sample. After marking, the equipped multi-clamp is removed and placed back on the flannel board. The decurling weight is removed and the free fiber end is clamped into the second multi-clamp. The measuring sample clamped between the two multi-clamps is suspended in a wire frame without tension. This wire frame is placed in the center of the heat shrink oven, which has been preheated to the correct treatment temperature (usually 200°C, 110°C, 80°C). After a treatment time of 5 minutes, the wire frame is removed from the oven. After the two multi-clamps have cooled, they are removed together with the measuring sample and placed on the flannel board. After an adaptation time of 30 minutes, a return measurement can be performed. For this purpose, the measuring sample is loaded with the decurling weight again and hung on the tripod. For the return measurement, the adjustable marking line of the tripod is positioned so that the upper edge of the marking point can be aligned with the marking line. The length of each fiber can now be read between the markings on the tripod counter with an accuracy of 1 / 10 mm.

[0128] Calculation of length change:

[0129]

[0130] Calculate the average of all 12 measurement samples. DETAILED DESCRIPTION

[0131] The present invention is illustrated by the following examples without limiting its scope thereto.

[0132] Example

[0133] The raw materials PLA 6202D and BioPBS Fz71PM from NatureWorks were spun into corresponding fibers using bicomponent spinning technology. The proportion of PLA as the core material was 70% by weight and the proportion of the cladding was 30% by weight. The total delivery rate set at an 827-hole nozzle and a traction speed of 1000 m / min was 331 g / min, resulting in a spinning fineness of 4.0 dtex. In addition, an antioxidant with an active substance content of 0.05% was added to PBS to achieve corresponding good spinning behavior at a spinning temperature of 240°C. As usual, a finishing agent was applied to the spinning material to ensure further processing.

[0134] The spun product was then processed on a conventional staple fiber conveyor line, with an undrawn tow thickness of about 42 ktex. Drawing to 2.2 dtex in a steam medium and fixing in a circulating air oven at 90°C resulted in the following textile technical parameters for the crimp variant for further processing in an air-laid process:

[0135] Fineness: 2.3dtex

[0136] Strength: 28cN / tec

[0137] Elongation: 41%

[0138] Shrinkage (110℃): 1.5%

[0139] Curl: 5 arcs / cm

[0140] BioPBS Fz71PM is a polybutylene succinate with a melt viscosity (190°C) of 200s -1 (shear) is 279Pa*s, at 1200s -1 (Shear) is 139Pa*s.

[0141] PLA 6202D is a polylactic acid with a relative density of 1.24 g / cm 3 (According to ASTM D792), its melt flow index (g / 10min@210°C) is in the range of 15 to 30. The glass transition temperature is 55 to 60°C (according to ASTM D3417), and the crystalline melting temperature is 160 to 170°C (according to ASTM D3418).

Claims

1. A bicomponent polymer fiber, wherein the fiber comprises component A as a core and component B as a sheath, and (i) the melting point of the thermoplastic polymer in component A is at least 5°C higher than the melting point of the thermoplastic polymer in component B, and (ii) the fiber material forming component A comprises biopolymer A and the fiber material forming component B comprises biopolymer B, (iii) biopolymer A is an aliphatic polyester of polylactic acid, and biopolymer B is an aliphatic polyester of polybutylene succinate and / or a copolymer of polybutylene succinate, wherein: Biopolymer B and biopolymer A differ in their chemical structures. characterised in that the bicomponent polymer fiber has a dry heat shrinkage measured at 110°C in the range of 0% to 10%, and the biopolymer A and the biopolymer B are each a biodegradable synthetic biopolymer according to ASTM D5338-15, Therein, the polymer fibers are stretched in the form of tows after spinning, the temperature during the tow stretching being between 30° C. and 80° C., and the stretching is carried out in the presence of steam.

2. The polymer fiber according to claim 1, characterized in that The biopolymer A is polylactic acid having a number average molecular weight (Mn) of at least 500 g / mol.

3. The polymer fiber according to claim 1 or 2, characterized in that The biopolymer A is polylactic acid having a number average molecular weight (Mn) of at most 1,000,000 g / mol.

4. The polymer fiber according to claim 1 or 2, characterized in that The biopolymer A is polylactic acid having a weight average molecular weight (Mw) in the range of 750 g / mol to 5,000,000 g / mol.

5. The polymer fiber according to claim 1, characterized in that The biopolymer A is polylactic acid having an intrinsic viscosity ranging from 0.5 dl / g to 8.0 dl / g as measured in chloroform at 25°C, 0.1% polymer concentration.

6. The polymer fiber according to claim 1, characterized in that The biopolymer A has a glass transition temperature greater than 20°C.

7. The polymer fiber according to claim 1, characterized in that The biopolymer B has a number average molecular weight (Mn) of at least 10,000 Daltons and at most 120,000 Daltons.

8. The polymer fiber according to claim 1, characterized in that The biopolymer B has a weight average molecular weight (Mw) of at least 50,000 Daltons and at most 240,000 Daltons.

9. The polymer fiber according to claim 1, characterized in that The biopolymer B has a melt flow index of 5 to 200 g / 10 minutes measured according to ASTM test method D1238-13.

10. The polymer fiber according to claim 1, characterized in that The biopolymer B has a glass transition temperature that is at least 5°C lower than the glass transition temperature of biopolymer A.

11. The polymer fiber according to claim 1, characterized in that The temperature at which the tow is stretched is above the glass transition temperature of biopolymers A and B.

12. The polymer fiber according to claim 11, characterized in that The filament bundle has 240 to 360 ktex before drawing.

13. The polymer fiber according to claim 11 or 12, characterized in that Biopolymer B has a number average molecular weight (Mn) of at least 10,000 Daltons and at most 30,000 Daltons.

14. The polymer fiber according to claim 13, characterized in that Biopolymer B has a temperature of 190 °C and a -1 The shear rate is in the range of 250 to 400 Pa*s and in the range of 1200s -1 The melt viscosity is in the range of 125 to 190 Pa*s at a shear rate of .

15. The polymer fiber according to claim 2, characterized in that The biopolymer A is polylactic acid having a number average molecular weight (Mn) of at least 1000 g / mol.

16. The polymer fiber according to claim 2, characterized in that The biopolymer A is polylactic acid having a number average molecular weight (Mn) of at least 5000 g / mol.

17. The polymer fiber according to claim 2, characterized in that The biopolymer A is polylactic acid having a number average molecular weight (Mn) of at least 10,000 g / mol.

18. The polymer fiber according to claim 2, characterized in that The biopolymer A is polylactic acid having a number average molecular weight (Mn) of at least 25,000 g / mol.

19. The polymer fiber according to claim 3, characterized in that The biopolymer A is polylactic acid having a number average molecular weight (Mn) of up to 500,000 g / mol.

20. The polymer fiber according to claim 3, characterized in that The biopolymer A is polylactic acid having a number average molecular weight (Mn) of up to 100,000 g / mol.

21. The polymer fiber according to claim 4, characterized in that The biopolymer A is polylactic acid having a weight average molecular weight (Mw) in the range of 5,000 g / mol to 1,000,000 g / mol.

22. The polymer fiber according to claim 4, characterized in that The biopolymer A is polylactic acid having a weight average molecular weight (Mw) in the range of 10,000 g / mol to 500,000 g / mol.

23. The polymer fiber according to claim 4, characterized in that The biopolymer A is polylactic acid having a weight average molecular weight (Mw) in the range of 30,000 g / mol to 500,000 g / mol.

24. The polymer fiber according to claim 4, characterized in that The polydispersity of biopolymer A ranged from 1.5 to 5.

25. The polymer fiber according to claim 5, characterized in that The biopolymer A is polylactic acid having an intrinsic viscosity ranging from 0.8 dl / g to 7.0 dl / g as measured in chloroform at 25°C, 0.1% polymer concentration.

26. The polymer fiber according to claim 5, characterized in that The biopolymer A is polylactic acid having an intrinsic viscosity ranging from 1.5 dl / g to 3.2 dl / g as measured in chloroform at 25°C, 0.1% polymer concentration.

27. The polymer fiber according to claim 6, characterized in that The biopolymer A has a glass transition temperature greater than 25°C.

28. The polymer fiber according to claim 6, characterized in that The biopolymer A has a glass transition temperature greater than 30°C.

29. The polymer fiber according to claim 6, characterized in that The biopolymer A has a glass transition temperature greater than 35°C.

30. The polymer fiber according to claim 6, characterized in that The biopolymer A has a glass transition temperature greater than 40°C.

31. The polymer fiber according to claim 7, characterized in that The biopolymer B has a number average molecular weight (Mn) of at least 12,000 Daltons and at most 100,000 Daltons.

32. The polymer fiber of claim 7, wherein The biopolymer B has a number average molecular weight (Mn) of at least 12,500 Daltons and at most 80,000 Daltons.

33. The polymer fiber of claim 8, wherein The biopolymer B has a weight average molecular weight (Mw) of at least 50,000 Daltons and at most 190,000 Daltons.

34. The polymer fiber of claim 8, wherein The biopolymer B has a weight average molecular weight (Mw) of at least 50,000 Daltons and at most 100,000 Daltons.

35. The polymer fiber of claim 9, wherein The biopolymer B has a melt flow index of 15 to 160 g / 10 minutes measured according to ASTM test method D1238-13.

36. The polymer fiber of claim 9, wherein The biopolymer B has a melt flow index of 20 to 120 g / 10 minutes measured according to ASTM test method D1238-13.

37. The polymer fiber of claim 10, wherein The biopolymer B has a glass transition temperature that is at least 10°C lower than the glass transition temperature of biopolymer A.

38. The polymer fiber of claim 10, wherein The biopolymer B has a glass transition temperature that is at least 15°C lower than the glass transition temperature of biopolymer A.

39. The polymer fiber of claim 11, wherein The stretch ratio is between 1.2 and 6.

0.

40. The polymer fiber of claim 13, wherein Biopolymer B has a number average molecular weight (Mn) of at least 12,000 Daltons and at most 28,000 Daltons.

41. The polymer fiber of claim 13, wherein Biopolymer B has a number average molecular weight (Mn) of at least 12,500 Daltons and at most 25,000 Daltons.

42. The polymer fiber of claim 14, wherein Biopolymer B has a temperature of 190 °C and a -1 The shear rate is in the range of 260 to 380 Pa*s and in the range of 1200s -1 The melt viscosity is in the range of 130 to 180 Pa*s at a shear rate of .

43. The polymer fiber of claim 14, wherein Biopolymer B has a temperature of 190 °C and a -1 The shear rate is in the range of 275 to 375 Pa*s and in the range of 1200s -1 The melt viscosity is in the range of 135 to 175 Pa*s at a shear rate of .

44. A textile fabric comprising polymer fibers as defined in any one of claims 1 to 43.

45. The textile fabric according to claim 44, characterized in that The textile fabric is a textile fabric that can be obtained according to a wet-laid web-forming process.

46. ​​Use of a polymer fiber as defined in any one of claims 1 to 43 for the preparation of an aqueous suspension.

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