KR20220119674A - Biodegradable polymer fibers made from renewable raw materials - Google Patents

Abstract

The present invention relates to a biodegradable polymer fiber composed of a renewable raw material having excellent physical properties, a method for preparing the same, and a use thereof.

Description

Biodegradable polymer fibers made from renewable raw materials

The present invention relates to biodegradable polymer fibers made from renewable raw materials having excellent physical properties, as well as methods for their preparation and uses thereof.

Polymer fibers, ie fibers based on synthetic polymers, are industrially produced in large quantities. For this purpose, the basic synthetic polymer is processed by a fusion spinning method. In this method, a thermoplastic polymer material is melted and directed through an extruder into a beam of radiation in a liquid state. The molten material is then guided in this beam of radiation into a so-called spinning nozzle. Spinning nozzles generally have spinning nozzles with a number of drilled holes into which individual capillaries (filaments) of fibers are stretched. In addition to the fusion spinning process, wet or solvent spinning methods are also used for the production of spun fibers. For this purpose, instead of a molten mass, a highly viscous solution of a synthetic polymer is drawn through a nozzle with fine drill holes. The person skilled in the art refers to both methods as the so-called multi-step spinning process.

The polymer fibers produced in this way are used for textile and/or technical applications. It is advantageous if the polymer fibers have good dispersion properties in aqueous systems, for example in the production of wet-laid fleece. Moreover, it is advantageous for fiber applications if the polymeric fibers have good mechanical properties that allow them to function well, for example in fiber post-processing, for example when drawn on a conveyor line. For textile applications, it is also advantageous if the thermal shrinkage of the polymer fibers in particular in the form of fleece is low.

At each end-use or necessary intermediate processing step, such as drawing and/or crimping, the polymeric fibers are usually modified or prepared by application of an appropriate finish or layer applied to the surface of the polymeric fiber to be finished or treated.

Another possibility of chemical modification can be realized in the polymer basic structure itself, for example, by incorporation of compounds with a flame-retardant effect in the polymer backbone and/or side chains.

In addition to this, additives such as antistatic or colored pigments may be incorporated into the molten thermoplastic polymer or polymer fibers during the multi-step spinning process.

The dispersion behavior of polymer fibers is influenced, among other things, by the properties of the synthetic polymer. In particular, for thermoplastic polymer fibers, the dispersion properties in aqueous systems are affected by the finish or layer applied to the surface.

In recent years, there is an additional need for textile systems that, besides being manufactured from renewable raw materials, not only meet the aforementioned requirements, but also require little or no adjustments in subsequent applications where possible, so that existing methods and machines can continue to be used. come.

Accordingly, the problem to be solved is to provide a polymer fiber of a renewable raw material with good physical properties and further biodegradability and low thermal shrinkage, so that the post-processing of the fiber can be good, for example, when drawing on a conveyor line. It is further advantageous if the polymer fibers of renewable raw material have good dispersing properties, especially long-term dispersibility which will still be effective after long-term storage.

The problem just described is solved by a bi-component polymer fiber according to the invention, which fiber comprises component A (core) and component B (shell), and in component A the melting point of the thermoplastic polymer is at least 5° C. higher than the melting point of the thermoplastic polymer of component B, wherein the fiber material comprises component A with biopolymer A, and wherein the fiber material comprises component B with biopolymer B. do.

The bicomponent polymer fibers are generally stored as tows after a spinning process and then drawn and post-processed on a conveyor line through a specific method. It is also possible to further machine the tow directly and the placing of the tow in a so-called canister can be partially or wholly omitted.

Combining a specific biopolymer, ie component A (core) and component B (shell) at a specific draw ratio, also results in a bicomponent polymer fiber according to the invention having a lower thermal shrinkage.

polymer

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

"Thermoplastic polymer" according to the invention means a plastic which can be molded (thermoplastically) within a certain temperature range, preferably in the range from 25°C to 350°C. This method is reversible. That is, as long as so-called thermal decomposition of the material due to overheating does not occur, it can be arbitrarily repeated several times by cooling and reheating to a molten state. This is where thermoplastic polymers differ from duroplasts and elastomers.

Among the so-called biopolymer-based thermoplastic polycondensates, synthetic biopolymers, especially synthetic biopolymers suitable for fusion spinning are preferred.

In the present invention, the term " synthetic biopolymer " refers to a material comprising a raw material of biological origin (renewable raw material). This is what distinguishes it from conventional crude oil-based materials or plastics such as polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC).

Bicomponent fibers are made from degradable synthetic biopolymers, where the term biodegradable is defined, for example, according to ASTM D5338-15 (To determine aerobic biodegradation of plastic materials under controlled composting conditions including thermophilic temperatures) Standard Test Methods for , ASTM International, West Conshohocken, PA, 2015, www.astm.org).

Biopolymer A (Core)

Synthetic biopolymer A comprising component A is a biopolymer comprising repeating units of an aliphatic polyester, in particular lactic acid, hydroxy butyric acid and/or glycolic acid, preferably lactic acid and/or glycolic acid, in particular lactic acid. Polylactic acid is particularly preferred for this purpose.

It is understood that an aliphatic polyester is typically a polyester having at least about 50 mol %, in some preferred embodiments at least about 60 mol %, and in more preferred embodiments at least about 70 mol % aliphatic monomer.

"Polylactic acid" is understood to mean a polymer comprising lactic acid units. Such polylactic acid is generally produced by condensation of lactic acid, but is also produced by ring-opening polymerization of lactide under appropriate conditions.

According to the invention, particularly suitable polylactic acids are poly(glycolide-co-L-lactide), poly(L-lactide), poly(L-lactide-co-ε-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 for example obtained from Boehringer Ingelheim Pharma KG (Germany) under the trade names Resomer ^® GL 903, Resomer ^® L 206 S, Resomer ^® L 207 S, Resomer ^® L 209 S, Resomer ^® L 210, Resomer ^® L 210 S, Resomer ^® LC 703 S, Resomer ^® LG 824 S, Resomer ^® LG 855 S, Resomer ^® LG 857 S, Resomer ^® LR 704 S, Resomer ^® LR 706 S, Resomer ^® LR 708, Resomer ^® LR 927 S, Resomer ^® RG 509 Available retail as S and Resomer ^® X 206 S.

For the purposes of the present invention, of particular interest are polylactic acids, in particular poly-D, poly-L or poly-D,L-lactic acids.

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

Other suitable materials for biopolymer A are polylactic acid, polyglycolic acid, polyalkylene carbonate (eg polyethylene carbonate), polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV) and copolymers or terpolymers based on polyhydroxybutyrate-hydroxyvalerate copolymer (PHBV).

In a most preferred embodiment, biopolymer A is a thermoplastic polymer based entirely on lactic acid.

The polylactic acid used according to the invention preferably has a number average molecular weight (Mn) of at least 500 g/mol, preferably a minimum (min) measured by gel permeation chromatography on narrowly dispersed polystyrene standards or end group repeats .) 1,000 g/mol, most preferably at least 5,000 g/mol, more preferably at least 10,000 g/mol, in particular at least 25,000 g/mol. On the other hand, the number average is preferably at most (max.) 1,000,000 g/mol, more preferably at most 500,000 g/mol, most preferably at most 100,000 g/mol, in particular at most 50,000 g/mol. Number average molecular weights ranging from a minimum of 10,000 g/mol to a maximum of 500,000 g/mol have also proven very advantageous within the scope of the present invention.

Number average molecular weight (Mw) of a preferred lactic acid polymer, in particular poly-D, poly-L or poly-D,L-lactic acid, preferably determined by gel permeation chromatography against a narrowly distributed polystyrene standard or end group repeats The weight average molecular weight (Mw) to be obtained is preferably in the range from 750 g/mol to 5,000,000 g/mol, more preferably from 5,000 g/mol to 1,000,000 g/mol, most preferably from 10,000 g/mol to 500.000 g/mol. and in particular in the range from 30,000 g/mol to 500,000 g/mol, and the polydispersity of these polymers is preferably in the range from 1.5 to 5.

The intrinsic viscosity of a particularly suitable lactic acid polymer, in particular poly-D, poly-L or poly-D,L-lactic acid, preferably measured in chloroform at 25° C., 0.1 % polymer concentration, is from 0.5 dl/g to 8.0 dl/g, preferably in the range from 0.8 dl/g to 7.0 dl/g, in particular in the range from 1.5 dl/g to 3.2 dl/g.

Within the scope of the present invention, biopolymers, in particular thermoplastic synthetic biopolymers, also have a glass transition temperature of greater than 20 °C, preferably greater than 25 °C, more preferably greater than 30 °C, most preferably greater than 35 °C, in particular 40 °C. It is very advantageous if it is above °C. Within the scope of the most 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.

Furthermore, the melting point is above 120°C, advantageously at least 130°C, preferably above 150°C, and at most 250°C, more preferably at most 210°C, most preferably in the range from 120°C to 250°C, in particular 150°C Polymers in the range from to 210° C. are particularly suitable.

For this purpose, the glass temperature and melting point of the polymer are preferably determined by means of dynamic scanning calorimetry (abbreviated "DSC"). In particular, the following procedures have proven beneficial in this context:

Biopolymer B (shell)

The synthetic biopolymer B comprising component B is preferably a biopolymer having a melting point at least 5° C. lower than the synthetic biopolymer A comprising component A. Preferably, the melting point of biopolymer A is at least 10 °C, more preferably at least 20 °C, most preferably at least 30 °C, in particular at least 40 °C higher than the melting point of synthetic biopolymer B.

Biopolymer B is an aliphatic polyester, in particular an aliphatic polyester having repeat units that differ from those of biopolymer A with respect to the chemical structure.

It is understood that an aliphatic polyester is typically a polyester having at least about 50 mol %, in some preferred embodiments at least about 60 mol %, and in more preferred embodiments at least about 70 mol % aliphatic monomer.

Biopolymer B has a number average molecular weight (Mn) of at least 10,000 daltons, in particular at least 12,000 daltons, more preferably at least 12,500 daltons and at most 120,000 daltons, in particular at most 100,000 daltons, most preferably at most 80,000 daltons. The number average molecular weight (Mn) is usually determined by gel permeation chromatography against a narrowly distributed polystyrene standard.

Biopolymer B generally has an average molecular weight (Mn) of at least 50,000 daltons and at most 240,000 daltons, in particular at most 190,000 daltons, most preferably at most 100,000 daltons. The number average molecular weight (Mn) is usually determined by gel permeation chromatography against a narrowly distributed polystyrene standard.

Biopolymer B generally has a melt flow index of 5 to 200 g/10 min, in particular 15 to 160 g/10 min, particularly preferably 20 to 120, as measured according to ASTM test procedure D1238-13. g/10 min (ASTM D1238-13, Standard Test Method for Melt Flow Rate of Thermoplastics by Extrusion Plastometer, ASTM International, West Conshohocken, PA, 2013, www.astm.org). The melt flow index is the weight (g) of polymer that can be compressed through an extrusion rheometer opening (0.0825 inches in diameter) when exposed to a force of 2160 g for 10 minutes at 190°C.

Biopolymer B preferably has an apparent viscosity of 50 to 215 Pa*s (Pascal seconds), more preferably 70 to 200 Pa*s, measured at a temperature of 160 °C and a shear force of 1000 s ^-1 (s = sec). to be. Biopolymers B based on aliphatic polyesters are generally difficult to process to high apparent viscosities, as well as seemingly too low viscosities generally result in stretched fibers that do not have any tensile strength and do not have sufficient bonding (thermal bonding). should consider doing

The melting point is above 50°C, advantageously at least 100°C, preferably above 120°C, at most 180°C, more preferably at most 160°C, most preferably in the range from 50°C to 160°C, in particular from 120°C to 160°C Biopolymer B, which is in the range of , is also particularly suitable.

The glass transition temperature of biopolymer B is preferably at least 5 °C, more preferably at least 10 °C and most preferably at least 15 °C lower than the glass transition temperature of biopolymer A. Glass transition temperature is measured by DSC

Examples of biopolymer B, which may have a low melting point and low glass transition temperature, include aliphatic polyesters having repeating units having at least 5 carbon atoms, such as polyhydroxyvalerate, polyhydroxybutyrate-hydroxyvalerate copolymer and poly caprolactone) and succinate-based aliphatic polymers such as polybutylene succinate, polybutylene succinate adipate and polyethylene succinate. More specific examples 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 from the prior art (WO 2007/070064) and are typically synthesized by polycondensation of a polyol with an aliphatic dicarbonate or anhydride.

In the context of the present invention, polybutylene succinate and butylene succinate copolymers are particularly preferred.

In particular, biopolymer B is suitable for thermal bonding with high enthalpy of melting and crystallization. In general, biopolymer B has a degree of crystallinity or latent heat of fusion (delta Hf) greater than approximately 25 Joules/gram (“J/g”), more preferably greater than 35 J/g, and most preferably greater than 50 J/g. is chosen Latent heat of melting (ΔHf), latent heat of crystallization (ΔHC) and crystallization temperature are measured by Digital Scanning Calorimetry (“DSC”) according to ASTM D-3418 (ASTM D3418-15, of Polymers of Melting and Crystallization by Differential Scanning Calorimetry) Standard Test Methods for Transition Temperature and Enthalpy, ASTM International, West Conshohocken, PA, 2015, www.astm.org).

The specific stretching performance with the set of parameters defined according to the invention also makes it possible to use more moderate modifications of biopolymer B, wherein the bicomponent-polymer fibers obtained in this way have less thermal shrinkage. In this way it is possible to use the widely available biopolymer B with these specific stretching parameters. The particular biopolymer B used in an embodiment according to the invention has a number average molecular weight (Mn) of at least 10,000 daltons, more preferably at least 12,000 daltons, most preferably at least 12,500 daltons and at most 30,000 daltons, preferably at most 28,000 daltons. , more preferably at most 25,000 Daltons. In general, the number average molecular weight (Mn) is determined by gel permeation chromatography against a narrowly distributed polystyrene standard.

Certain biopolymers B have a melting point greater than 50 °C, advantageously at least 100 °C, preferably greater than 120 °C, and at most 180 °C, more preferably at most 160 °C, most preferably in the range of 50 °C to 160 °C, in particular in the range of 120°C to 160°C.

The glass transition temperature of the particular biopolymer B is preferably at least 5° C., more preferably at least 10° C. and most preferably at least 15° C. lower than the glass transition temperature of biopolymer A. The glass transition temperature is measured by DSC.

Examples of certain biopolymers B that may have low melting points and low glass transition temperatures include aliphatic polyesters having repeat units having at least 5 carbon atoms, such as polyhydroxyvalerate, polyhydroxybutyrate-hydroxyvalerate copolymers and polycaprolactone) and succinate-based aliphatic polymers such as polybutylene succinate, polybutylene succinate adipate and polyethylene succinate. More specific examples 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.

In the context of the present invention, particular preference is given to polybutylene succinate and butylene succinate copolymers as specific biopolymer B.

In particular, certain biopolymer B is suitable for thermal bonding with high enthalpy of melting and crystallization. In general, biopolymer B has a degree of crystallinity or latent heat of fusion (delta Hf) greater than approximately 25 Joules/gram (“J/g”), more preferably greater than 35 J/g, and most preferably greater than 50 J/g. is chosen Latent heat of melting (ΔHf), latent heat of crystallization (ΔHC) and crystallization temperature are measured by Digital Scanning Calorimetry (“DSC”) according to ASTM D-3418 (ASTM D3418-15, of Polymers of Melting and Crystallization by Differential Scanning Calorimetry) Standard Test Methods for Transition Temperature and Enthalpy, ASTM International, West Conshohocken, PA, 2015, www.astm.org).

Specific biopolymer B has a melt viscosity (Gottfert Rheo-Tester 1000) measured at a temperature of 190 ° C in the range of 250 to 400 Pa*s at 200 s ⁻¹ (shear) and 125 to 1200 s ⁻¹ (shear) 190 Pa*s in the range, preferably in the range of 260 to 380 Pa*s at 200 s ^-1 (shear) and 130 to 180 Pa*s at 1200 s ^-1 (shear), more preferably 200 s ^-1 (shear) ) from 275 to 375 Pa*s and from 1200 s ⁻¹ (shear) to 135 to 175 Pa*s.

Additives in Polymers A and B

The biopolymers A and B described above contain common additives, for example, antioxidants. In this regard, it has been demonstrated that the additives of the antioxidant group are unavoidable in the manufacture and post-processing of fibers because the aforementioned biopolymers A and B are sensitive to oxidative degradation.

Other common additives include pigments, stabilizers, surfactants, waxes, flow promoters, solid solvents, plasticisers and other materials such as , nucleating agents, which are added to improve the processability of thermoplastic compositions.

The aforementioned biopolymers B, in particular certain biopolymers B based on the aforementioned properties, can already be performed with reduced content of additives, in particular nucleating agents. These nucleating agents, which are usually added, simplify crystallization during fiber cooling, thereby simplifying their processing. One type of such nucleating agent is a polycarbonate acid such as succinic acid, glutaric acid, adipic acid, pimelic acid, morphic acid, azelaic acid, sebacic acid and mixtures of these acids as described in US Pat. No. 6,177,193. to be. The nucleating agent is typically present in biopolymer B at 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.

At least 90% by weight of the bicomponent fiber according to the present invention comprises the above-mentioned aliphatic polyester biopolymers A and B, and is typically less than about 10% by weight, preferably about 8% by weight of the biopolymer B forming the shell. %, more preferably less than about 5% by weight additive.

As mentioned above, the biopolymers described above require the addition of antioxidants, especially due to the susceptibility to oxidative degradation of biopolymer B (shell).

Based on the selected formulation and post-processing of the raw materials, the content of antioxidants can be significantly reduced. That is, the concentration of the antioxidant in the biopolymer B (shell) is 0.025 to 0.2 wt%.

The bicomponent fibers according to the invention are spun and post-processed on a conveyor line using methods known from the prior art and then joined into tows, in particular they are drawn and further crimped or texturing if necessary. By selecting specific conveyor line parameters in the stretching, in particular the specific biopolymer B described above can be used.

polymer fiber

The bicomponent fibers according to the invention can be provided as finite fibers, for example so-called staple fibers or endless fibers (filaments). For better dispersibility, the fibers are preferably present as staple fibers. The length of the staple fibers mentioned above is not subject to any fundamental limitation, but is generally from 2 to 200 mm, preferably from 3 to 120 mm, more preferably from 4 to 60 mm.

The single yarn count of the bicomponent fiber according to the invention, preferably the staple fiber, is 0.5 to 30 dtex, preferably 0.7 to 13 dtex. For some applications, a yarn count of 0.5 to 3 dtex and a fiber length of <10 mm, preferably <8 mm, more preferably <6 mm, most preferably <5 mm are particularly suitable.

The bicomponent fibers according to the invention exhibit low hot-air heat shrinkage in the range of 0% to 10%, preferably >0% to 8%, each measured at 110°C.

The combination of a specific biopolymer, i.e., a specific biopolymer B, which is component A (core) and component B (shell), at a specific draw ratio, can also transmit a draw force to the core material, thus reaching stretch-induced crystallization. In the bicomponent polymer fiber according to the invention, this leads to a low thermal shrinkage rate as described above.

The polymer fibers according to the invention are generally produced by conventional procedures. Initially, if necessary, the polymer is dried and fed into the extruder. Then, the molten material is spun using standard equipment with corresponding nozzles. The exit velocity of the nozzle exit surface is adjusted with the spinning velocity to produce fibers with the desired yarn count. Spinning speed is understood to mean the speed at which a hard filament is pulled.

The formed fibers may have a circular, elliptical or further suitable cross-section and shape.

The fiber filaments produced in this way are incorporated into yarns which in turn are incorporated into tows. The tow is initially placed in a cannister for further processing. Tows stored intermittently in canisters are picked up to make large spun fiber tows.

Another object of the present invention is to post-process using an existing conveyor line with specific stretching of the spun fiber tow produced by the disclosed method, which generally has 10 to 600 ktex and is produced by the disclosed method. The feed rate of the spun fiber tow of the draw or drawframe is preferably 10 to 110 m/min (feed rate). Manufacturing can continue at this point, which promotes elongation but does not adversely affect the following properties.

Stretching can be implemented as a one-step process or optionally by application of a two-step drawing method (see, for example, US 3 816 486 in this regard). One or more finishes may be applied before and during stretching and when applying conventional methods.

The stretching according to the invention is carried out with a draw ratio of 1.2 to 6.0, preferably 2.0 to 4.0, especially when using the specific biopolymer B, wherein the temperature during drawing of the spun tow is from 30° C. to 80° C. Thus, stretching occurs within the glass transition temperature range of the spun tow to be stretched. The drawing according to the invention takes place under steam, ie in a so-called steam chest, so that the drawing point of the fibers is reached in the steam chest. Steam chests are normally operated at a pressure of 3 bar.

By stretching under steam in the temperature range described above, the thermal shrinkage of the fibers can be reduced and adjusted in an intentional and controlled manner.

A preferred conveyor line setup is as follows:

Stretching takes place in the steam chest as a one-step process between stretching machines S2 and S1. That is, the draw point of the fiber reaches the steam chest. The temperature of all godets (usually 7) of S1 is 30 to 80 °C. Full stretching takes place in the steam chest. The steam chest is preferably operated at 3 bar steam pressure.

All godets (usually 7) of the next drawing machine S2 are low temperature, where low temperature means room temperature (about 20 to 35° C.). This so-called "low temperature stretching" mode has the effect that stretching is not fixed at high temperature in the S2 phase under tension. Cold S2 has the advantage that there is no risk of individual fibers sticking to the hot godet of S2. Despite "low temperature stretching", the fibers are nevertheless held in an oven without tension, are insensitive to high temperatures and can withstand temperatures up to 100° C. without sticking. "Low temperature stretching" as described above is particularly suitable for polybutylene succinate (FZ71), the melt viscosity of which is measured at a temperature of 190° C. (Gottfert Rheo-Tester 1000) and ranges from 250 to 250 s -1 (shear) at 200 s ^-1 (shear). 325 Pa*s in the range and 125 to 150 Pa*s at 1200 s ^-1 (shear), preferably 260 to 300 Pa*s at 200 s ^-1 (shear) and 130 at 1200 s ^-1 (shear) to 150 Pa*s, more preferably from 270 to 290 Pa*s at 200 s ⁻¹ (shear) and 135 to 145 Pa*s at 1200 s ⁻¹ (shear).

Melt viscosity (Gottfert Rheo-Tester 1000) measured at a temperature of 190 °C for polybutylene succinate (FZ91) in the range of 340 to 400 Pa*s at 200 s ⁻¹ (shear) and 1200 s ⁻¹ (shear) 150 to 190 Pa*s at, preferably 350 to 390 Pa*s at 200 s ⁻¹ (shear), 160 to 185 Pa*s at 1200 s ⁻¹ (shear), more preferably 200 s ⁻ Stretching machine S2 is operated in a temperature range of 60°C to 100°C, as long as it ranges from 360 to 385 Pa*s at ¹ (shear) and 165 to 180 Pa*s at 1200 s ⁻¹ (shear). That is, all godets (usually 7) have the aforementioned temperature.

The spun tow preferably has 240 to 360 ktex before drawing.

As with the crimping/texturing of the drawn fiber, if necessary, a conventional mechanical crimping method can be applied using a generally known crimping machine. Preference is given to mechanical devices for crimping fibers, eg compression chambers, which operate for example with the aid of steam. However, fibers that have been crimped using other methods may also be used, for example fibers that have been crimped three-dimensionally. To effect crimping, the tow is initially brought to a temperature generally in the range of 50 to 100 °C, preferably 70 to 85 °C, more preferably about 78 °C, 1.0 to 6.0 bar, more preferably about 2.0 With a pressure of the tow infeed roller of bar, a pressure of the crimping chamber of 0.5 to 6.0 bar, more preferably 1.5 to 3.0 bar, 1.0 to 2.0 kg/min, more preferably 1.5 kg/min of steam processed

This is also done at temperatures up to 130° C. as long as smooth or where applicable crimped fibers are relaxed and/or set in an oven or hot air stream.

To produce staple fibers, smooth or, where applicable, crimped fibers are cut and, where applicable, deposited in flake form on hardening and pressing rolls. The staple fibers of the present invention are preferably cut upon relaxation of the downstream mechanical cutting unit. Cutting can be omitted to produce a tow type. These tow types are deposited into rolls uncut and pressed.

Insofar as the fibers according to the invention are provided in a crimped embodiment, the degree of crimp is preferably at least 2 crimps per cm (fiber curls), preferably at least 3 crimps per cm, more preferably 3 crimps per cm. to 9.8 curls, most preferably 3.9 curls per cm to 8.9 curls per cm. For use for producing textile webs, values of 5 to 5.5 curls per cm for crimp degree are most preferred. If the textile web is produced by the wet method, it may be necessary to individually adjust the crimp degree.

A textile web can be produced from the fibers according to the invention, which is also the subject of the invention. Based on the good dispersibility of the fibers according to the invention, such textile webs are preferably produced by a wet method.

Accordingly, the term "textile web" should be understood in its broadest sense in the context of this description. The textile web can be in any form comprising the fibers according to the invention and produced according to web forming techniques. An example of such a textile web is a fleece, in particular a wet fleece, preferably based on staple fibers, which is produced by thermal bonding.

The fibers according to the invention also have good dispersion persistence. That is, the fibers will continue to have very good dispersion quality even after storage in rolls or similar forms for longer periods of time, such as weeks or months. Moreover, the fibers according to the invention have good long-term dispersion qualities. That is, when fibers are dispersed in a liquid medium, for example in water, the fibers remain dispersed longer and begin to settle only after a longer period of time.

Test Methods:

Unless otherwise specified in the preceding description, the following measurement or test methods are used:

Yarn count:

The yarn number was determined according to DIN EN ISO 1973.

Dispersibility:

For dispersibility evaluation, the following test methods were developed and applied according to the present invention:

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

Then, the fiber/deionized water mixture is stirred for at least 3 minutes (rotation speed about 750-1500 rpm) using a laboratory magnetic mixer (eg IKAMAG RCT) and [sic magnetic fish] (80 mm) and then the mixer to stop It is then determined whether all fibers have been dispersed.

This dispersion behavior of the fibers is now evaluated as follows:

not distributed (-)

Partially distributed (o)

Fully Distributed (+)

The above evaluation is based on a defined time interval.

biodegradable

Measured according to ASTM D5338-15 (Standard Test Method for Determination of Aerobic Biodegradation of Plastic Materials under Controlled Composting Conditions Including Thermophilic Temperature, ASTM International, West Conshohocken, PA, 2015, www.astm.org).

Number average molecular weight (Mn)

Measured by gel permeation chromatography against a narrowly distributed polystyrene standard by end-group titration.

Weight average molecular weight (Mw)

Measured by gel permeation chromatography against a narrowly distributed polystyrene standard by end-group titration.

intrinsic viscosity

Determined via GPC by measurement in chloroform at 25° C., 0.1% polymer concentration.

Glass transition temperature and melting point

It is determined by dynamic differential scanning calorimetry (abbreviated "DSC") according to the following procedure:

DSC measurement performance under nitrogen, corrected for indium.

nitrogen flow is 50 ml/min; The initial weight of the fibers is in the range of 2-3 mg.

The temperature range is from -50 °C to 210 °C at 10 K/min, then held isothermal for 5 min, and finally back to -50 °C at 10 K/min.

The final temperature is usually always about 50 °C higher than the highest predicted melting point.

DSC measurements are performed using a TA/Waters Model Q100.

melt viscosity

Melt viscosity is determined using a Gottfert Rheo Tester 1000 at a temperature of 190 °C at 200 s ^-1 (shear) and 1200 s ^-1 (shear).

apparent viscosity

determined as described in WO 200//070064.

melt flow index

Determined according to ASTM test method D1238-13 (ASTM D1238-13, Standard Test Method for Melt Flow Rate of Thermoplastic Resins by Extrusion Plastometer, ASTM International, West Conshohocken, PA, 2013, www.astm.org). The melt flow index is the weight (g) of polymer that can be compressed through an extrusion rheometer opening (0.0825 inch diameter) when exposed to a force of 2160 g for 10 minutes at 190°C.

latent heat of melting

Latent heat of melting (ΔHf), latent heat of crystallization (ΔHC) and crystallization temperature are measured by Digital Scanning Calorimetry (“DSC”) according to ASTM D-3418 (ASTM D3418-15, of Polymers of Melting and Crystallization by Differential Scanning Calorimetry) Standard Test Methods for Transition Temperature and Enthalpy, ASTM International, West Conshohocken, PA, 2015, www.astm.org).

heat shrinkage

Twelve fibers (measured samples) are extracted from the tow sample. Using tweezers, secure one end of these fibers with a multi-clamp and the other end with a de-crimp weight. Measured from a PLA/PBS (core/shell) type bicomponent fiber with a yarn count of 2.2 dtex, the de-crimp weight is 190 mg. The multi-clamp loaded with the measurement sample is fixed to the stand so that the measurement sample is freely suspended by the prestressing force of the stand. The chosen starting length (typically 150 mm) is marked on each fiber. This is done by the marking lines on the stand and the marking points on the sample. After marking, lower the loaded multi-clamp and place it on the velvet sheet. The crimp removal pad is removed and the free fiber end is secured in a second multi-clamp. A measurement sample held between two multi-clamps is connected to a wire rack without tension. This wire rack is inserted into the center of a preheated shrink oven heated to the correct processing temperature (normal temperatures are 200 °C, 110 °C, 80 °C). After a processing time of 5 minutes, the wire rack is removed from the oven. After the two multi-clamps have cooled, they are taken out together with the measurement sample and placed on a velvet sheet. After 30 minutes of acclimatization time, back measurement is possible. To do this, reload the de-crimp weight on the measurement sample and connect it to the stand. The adjustable marker lines on the stand are positioned for back measurement so that the top edge of each marker can be covered with the marker line. Now, the length between the marks on the counter of the stand is read with precision down to 1/10 mm individually for each fiber.

Calculation of change in length:

It calculates the average value of all 12 measurement samples.

The present invention is illustrated by the following examples, but the scope is not limited thereto.

Example

NatureWorks' raw materials PLA 6202D and BioPBS Fz71PM were spun into the corresponding fibers through a two-component spinning technique. The PLA concentration as core material was 70 wt % and the shell % was 30 wt %. A total set transport of 331 g/min using a nozzle with 827 bores and a discharge velocity of 1000 m/min produced a spun yarn count of 4.0 dtex. In addition, an antioxidant with an active substance concentration of 0.05% was added to PBS to achieve a corresponding good spinning behavior at a spinning temperature of 240°C. As usual, a finish was applied to the spun material to allow further processing.

The spun product was then processed on an existing staple fiber line to an undrawn tow length of about 42 ktex. The following fiber technology key values of crimp deformation, drawn in a steam medium at 2.2 dtex and fixed at 90 °C in a circulating air oven, were generated for further processing in the airlay process:

Linear Density: 2.3 dtex

Hardness : 28 cN/tec

Elongation: 41%

Shrinkage (110 °C): 1.5%

crimp: 5 Bg/cm

BioPBS Fz71PM is a polybutylene succinate having a melt viscosity (190° C.) of 279 Pa*s at 200 s ⁻¹ (shear) and 139 Pa*s at 1200 s ⁻¹ (shear).

PLA 6202D is a polylactic acid with a relative density of 1.24 g/cm ³ (according to ASTM D792) and a melt flow index (g/10 min at 210° C.) ranging from 15 to 30. The glass transition temperature is between 55 and 60 °C (according to ASTM D3417) and the crystalline melting temperature is between 160 and 170 °C (according to ASTM D3418).

Claims (20)

A bi-component polymer fiber, wherein the fiber comprises component A (core) and component B (shell);
(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;
(ii) the fiber material comprising component A comprises biopolymer A and the fiber material comprising component B comprises biopolymer B;
(iii) biopolymer A is a biopolymer comprising repeating units of an aliphatic polyester, preferably lactic acid, biopolymer B is an aliphatic polyester, and biopolymer B and biopolymer A have different chemical structures;
wherein the bicomponent polymer fiber has a hot-air thermal shrink rate in the range of 0% to 10% as measured at 110°C. The bicomponent polymer fiber of claim 1 , wherein biopolymer A and biopolymer B each are biodegradable synthetic biopolymers according to ASTM D5338-15. 3 . The biopolymer A according to claim 1 , wherein the biopolymer A comprises repeating units of lactic acid, hydroxy butyric acid and/or glycolic acid, preferably comprising repeating units of lactic acid and/or glycolic acid, in particular of lactic acid. A bicomponent polymer fiber, characterized in that it comprises repeat units. 4 . The biopolymer A according to claim 1 , wherein the biopolymer A has a number average molecular weight (Mn) of at least (min.) 500 g/mol, preferably at least 1,000 g/mol, more preferably at least 5,000. A bicomponent polymer fiber, characterized in that it is polylactic acid in g/mol, most preferably at least 10,000 g/mol, in particular at least 25,000 g/mol. 5. The biopolymer A according to any one of the preceding claims, wherein the biopolymer A has a number average molecular weight (Mn) of at most (max.) 1,000,000 g/mol, preferably at most 500,000 g/mol, in particular at most 100,000 g/mol. A bicomponent polymer fiber, characterized in that it is phosphorus polylactic acid. 4. The biopolymer A according to any one of claims 1 to 3, wherein the biopolymer A has a number average molecular weight (Mw) in the range from 750 g/mol to 5,000,000 g/mol, preferably from 5,000 g/mol to 1,000,000 g/mol. polylactic acids in the range, more preferably in the range from 10,000 g/mol to 500,000 g/mol, most preferably in the range from 30,000 g/mol to 500,000 g/mol, the polydispersity of these polymers being A bicomponent polymer fiber, characterized in that it ranges from 1.5 to 5. 7. The biopolymer A according to any one of claims 1 to 6, wherein the biopolymer A has an intrinsic viscosity in the range of 0.5 dl/g to 8.0 dl/g, preferably 0.8 dl, measured in chloroform at a concentration of 0.1% polymer at 25°C. A bicomponent polymer fiber, characterized in that it is polylactic acid in the range of /g to 7.0 dl/g, more preferably in the range 1.5 dl/g to 3.2 dl/g. 8. The biopolymer A according to any one of claims 1 to 7, wherein the biopolymer A has a glass transition temperature of greater than 20 °C, preferably greater than 25 °C, in particular greater than 30 °C, more preferably greater than 35 °C, in particular greater than 40 °C. Characterized in that, bicomponent polymer fibers. 9. The biopolymer B according to any one of claims 1 to 8, wherein the biopolymer B has a number average molecular weight (Mn) of at least 10,000 daltons, in particular at least 12,000 daltons, more preferably at least 12,500 daltons, at most 120,000 daltons, in particular A bicomponent polymer fiber, characterized in that it is at most 100,000 Daltons, most preferably at most 80,000 Daltons. 9. The method according to any one of the preceding claims, characterized in that biopolymer B has an average molecular weight (Mn) of at least 50,000 daltons, at most 240,000 daltons, in particular at most 190,000 daltons, most preferably at most 100,000 daltons, 2 component polymer fiber. 11. The method according to any one of claims 1 to 10, wherein the biopolymer B has a melt flow index measured according to ASTM test method D1238-13 of 5 to 200 g/10 min, in particular 15 to 160 g/10 min, more than Bicomponent polymer fibers, characterized in that preferably 20 to 120 g/10 min. 12. The biopolymer according to any one of claims 1 to 11, wherein biopolymer B has a glass transition temperature of at least 5 °C, more preferably at least 10 °C and most preferably at least 15 °C higher than the glass transition temperature of biopolymer A. Characterized in low, bicomponent polymer fibers. 13. Biopolymer B according to any one of claims 1 to 12, wherein biopolymer B is an aliphatic polyester having repeating units having at least 5 carbon atoms, preferred biopolymer B is polyhydroxyvalerate, polyhydroxybutyrate-hydroxyvalerate late copolymers and aliphatic polymers based on polycaprolactone and succinate, in particular polybutylene succinate, polybutylene succinate adipate and polyethylene succinate as well as polyethylene oxalate, polyethylene malonate, polyethylene succinate, polypropylene oxalate , polypropylene malonate, polypropylene succinate, polybutylene oxalate, polybutylene malonate, polybutylene succinate and mixtures thereof and copolymers of these compounds. 14. Bicomponent polymer fiber according to claim 13, characterized in that biopolymer B is polybutylene succinate and/or polybutylene succinate copolymer. 15. The biomaterial according to any one of claims 1 to 14, wherein the polymer fiber is stretched after spinning in the form of a tow, and the temperature during stretching of the tow is 30°C to 80°C, so that the bio A bicomponent polymer fiber, characterized in that it is higher than the glass transition temperatures of polymers A and B, and the stretching is carried out with exposure to steam, preferably at an elongation of 1.2 to 6.0. 16. The bicomponent polymer fiber of claim 15, wherein the spun tow has a yarn count of 240 to 360 ktex before drawing. 17. The biopolymer B according to claim 15 or 16, wherein the biopolymer B has a number average molecular weight (Mn) of at least 10,000 daltons, in particular at least 12,000 daltons, more preferably at least 12,500 daltons, at most 30,000 daltons, in particular at most 28,000 daltons, most preferably is up to 25,000 Daltons. 18. The method of claim 17, wherein the biopolymer B has a melt viscosity measured at a temperature of 190 °C in the range of 250 to 400 Pa*s at 200 s ⁻¹ (shear) and 125 to 190 Pa at 1200 s ⁻¹ (shear) *s in the range, preferably in the range of 200 s ^-1 (shear) to 260 to 380 Pa*s and 1200 s ^-1 (shear) to 130 to 180 Pa*s, more preferably in 200 s ^-1 (shear). A bicomponent polymer fiber, characterized in that it ranges from 275 to 375 Pa*s and from 135 to 175 Pa*s at 1200 s ⁻¹ (shear). A textile web, in particular obtained from a wet-laid procedure, comprising polymer fibers according to any one of claims 1 to 18. Use of a polymer fiber according to any one of claims 1 to 18 for producing an aqueous suspension.