JP7234217B2 - Polymer fiber with improved long-term dispersibility - Google Patents

Description

The present invention relates to polymeric fibers with improved long-term dispersibility, as well as methods of making and uses thereof.

Polymer fibers, ie fibers based on synthetic polymers, are produced industrially on a large scale. In this case, the underlying synthetic polymer is produced by a melt spinning process. For this, the thermoplastic polymer material is melted and delivered in liquid form by an extruder to a spinning beam. Molten material is fed from this spinning beam to a so-called spinneret. A spinneret typically has a spinneret plate with multiple holes from which individual capillaries of fiber (filaments) are extruded. In addition to melt spinning methods, wet spinning methods or solvent spinning methods are also used for the production of spun fibers. In this case, a highly viscous solution of synthetic polymer, rather than a melt, is extruded through a fine-pored die. Both methods are referred to by those skilled in the art as the so-called multi-position spinning method.

Polymer fibers produced in this way are used in textile and/or technical applications. It is advantageous here for the polymer fibers to have good dispersibility in aqueous systems, for example for the production of wet-laid nonwovens. Furthermore, it is advantageous for textile applications when the polymer fibers have a good soft hand.

Modifications or finishing for the specific end use of the polymer fiber or necessary intermediate processing steps such as drawing and/or crimping are usually applied to the finished polymer fiber or the surface of the polymer fiber to be treated. This is achieved by the application of suitable finishes or layers.

Another approach for chemical modification can be achieved by incorporating compounds with flame retardant action into the polymer substructure, eg into the polymer backbone and/or side chains.

Additionally, additives such as antistatic agents or colored pigments can be introduced into the molten thermoplastic polymer or into the polymer fibers during the multi-position spinning process.

The dispersion behavior of polymer fibers is influenced inter alia by the properties of the synthetic polymer. Thus, particularly in the case of fibers of thermoplastic polymers, dispersibility in aqueous systems is influenced and controlled by the finish or layer applied to the surface.

The dispersibility provided or improved by a suitable finish or layer is already sufficient for many textile applications.

However, for food related applications different requirements apply. Substances and materials used must be approved for food contact according to EU Regulation No. 231/2012. In addition, the finished polymer fibers are subjected to relatively long periods of time and/or under more severe conditions, such as under high pressure, strong shear forces and elevated temperatures, especially also in aggressive acidic aqueous systems. It is desirable if it exists in dispersed form and this dispersibility is retained even after relatively long storage times.

Thus, polymer fibers with improved dispersibility, in particular long-term dispersibility, which have good dispersibility even after relatively long-term storage and which furthermore are suitable for use in food products in accordance with EU Regulation No. 231/2012. There is the problem of providing polymer fibers that are approved for contact with. Furthermore, the polymer fibers have, under severe conditions, i.e. under high pressure, severe shear forces and elevated temperatures, in particular and optionally a pH of less than 7 and/or electrolyte-based, in particular salts. It should be readily dispersible even in aggressive aqueous systems with aggressive electrolytes and this good dispersibility should be retained even after relatively long storage.

The subject is a polymer fiber according to the invention comprising at least one synthetic polymer, preferably at least one synthetic thermoplastic polymer, said fiber having on its surface carboxymethylcellulose (CMC), methylcellulose (MC) , ethylcellulose (EC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), methylethylcellulose (MEC), hydroxyethylmethylcellulose (HEMC), hydroxypropylmethylcellulose (HPMC), ethylhydroxyethylcellulose, carboxymethylhydroxyethylcellulose and their A polymer fiber solution characterized in that it has a formulation comprising at least one cellulose ether selected from the group of mixtures.

The synthetic polymers according to the invention forming the polymer dispersion medium are preferably thermoplastic polymers, in particular thermoplastic polycondensates, particularly preferably so-called synthetic biopolymers, particularly preferably thermoplastic polymers based on so-called biopolymers. Contains condensates.

The term "thermoplastic polymer" refers in the present invention to plastics that are (thermoplastically) deformable in a certain temperature range, preferably in the range of 25°C to 350°C. This process is reversible, ie it can be repeated with any frequency by cooling and reheating to the molten state, as long as overheating does not initiate so-called pyrolysis of the material. This is the difference between thermoplastic polymers and thermosets and elastomers.

Within the scope of the present invention, the following polymers are preferably what is meant by the term "thermoplastic polymer":
Acrylonitrile ethylene propylene (diene) styrene copolymer, acrylonitrile methacrylate copolymer, acrylonitrile methyl methacrylate copolymer, acrylonitrile chlorinated polyethylene styrene copolymer, acrylonitrile butadiene styrene copolymer, acrylonitrile ethylene propylene styrene copolymer, aromatic polyester, acrylonitrile styrene acryloester copolymer, butadiene styrene copolymer , cellulose acetate, cellulose acetobutyrate, cellulose acetopropionate, cellulose hydrate, carboxymethyl cellulose, cellulose nitrate, cellulose propionate, cellulose triacetate, polyvinyl chloride, ethylene acrylic acid copolymer, ethylene butyl acrylate copolymer, ethylene chlorotriate Fluoroethylene copolymer, ethylene ethyl acrylate copolymer, ethylene methacrylate copolymer, ethylene methacrylic acid copolymer, ethylene tetrafluoroethylene copolymer, ethylene vinyl alcohol copolymer, ethylene butene copolymer, ethyl cellulose, polystyrene, polyfluoroethylene propylene, methyl methacrylate acrylonitrile butadiene styrene copolymer, methyl Methacrylate Butadiene Styrene Copolymer, Methylcellulose, Polyamide 11, Polyamide 12, Polyamide 46, Polyamide 6, Polyamide 6-3-T, Polyamide 6-Terephthalic Acid Copolymer, Polyamide 66, Polyamide 69, Polyamide 610, Polyamide 612, Polyamide 6I, Polyamide MXD 6, polyamide PDA-T, polyamide, polyarylether, polyaryletherketone, polyamideimide, polyarylamide, polyamino-bis-maleimide, polyarylate, polybutene-1, polybutylacrylate, polybenzimidazole, Poly-bis-maleimide, polyoxadiazobenzimidazole, polybutylene terephthalate, polycarbonate, polychlorotrifluoroethylene, polyethylene, polyester carbonate, polyaryletherketone, polyetheretherketone, polyetherimide, polyetherketone, polyethylene oxide, Polyarylethersulfone, polyethylene terephthalate, polyimide, polyisobutylene, poly isocyanurate, polyimide sulfone, polymethacrylimide, polymethacrylate, poly-4-methylpentene-1, polyacetal, polypropylene, polyphenylene oxide, polypropylene oxide, polyphenylene sulfide, polyphenylene sulfone, polystyrene, polysulfone, polytetrafluoroethylene, polyurethane, poly Vinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinylidene chloride, polyvinylidene fluoride, polyvinyl fluoride, polyvinyl methyl ether, polyvinyl pyrrolidone, styrene butadiene copolymer, styrene isoprene copolymer, styrene maleic anhydride copolymer, styrene maleic anhydride butadiene copolymer, styrene methyl methacrylate copolymer, styrene methyl styrene copolymer, styrene acrylonitrile copolymer, vinyl chloride ethylene copolymer, vinyl chloride methacrylate copolymer, vinyl chloride maleic anhydride copolymer, vinyl chloride maleimide copolymer, vinyl chloride methyl methacrylate copolymer, vinyl chloride octyl acrylate copolymer , vinyl chloride vinyl acetate copolymer, vinyl chloride vinylidene chloride copolymer, and vinyl chloride vinylidene chloride acrylonitrile copolymer.

Within the scope of the present invention, the term "thermoplastic polymer" preferably means a polymer that is chemically and/or physically different from the cellulose ethers used in the preparation. The thread-forming thermoplastic polymer preferably does not contain any cellulose ethers.

Particularly suitable are high-melting thermoplastic polymers (melting point above 100° C.) which are very suitable for the production of spun fibres.

Suitable high-melting thermoplastic polymers include, for example, polyhexamethylene adipinamide, polycaprolactam, polyamides such as aromatic or partially aromatic polyamides (“aramids”), aliphatic polyamides such as Nylon, partially aromatic or wholly aromatic Polymers having ether and keto groups such as polyester, polyphenylene sulfide (PPS), polyetherketone (PEK) and polyetheretherketone (PEEK), or polyolefins such as polyethylene or polypropylene.

Among high melting point thermoplastic polymers, melt spinnable polymers are particularly preferred.

Melt-spinnable polyesters consist primarily of structural units derived from aromatic dicarboxylic acids and aliphatic diols. Common aromatic dicarboxylic acid building blocks are divalent radicals of benzenedicarboxylic acids, especially terephthalic acid and isophthalic acid, common diols having 2 to 4 carbon atoms, where ethylene glycol and /or propane-1,3-diol is particularly suitable.

Especially preferred are polyesters with at least 95 mol % polyethylene terephthalate (PET).

Such polyesters, especially polyethylene terephthalate, usually have molecular weights corresponding to intrinsic viscosities (IV) of 0.4 (dl/g) to 1.4 (dl/g) measured on dichloroacetic acid solutions at 25°C. have

The term "synthetic biopolymer" refers in the present invention to materials that consist exclusively of biogenic raw materials (renewable raw materials). It is thus distinguished from conventional petroleum-based materials or plastics such as, for example, polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC).

According to the invention, particularly preferred synthetic biopolymers are thermoplastic polycondensates based on so-called biopolymers containing repeating units of lactic acid, hydroxybutyric acid and/or glycolic acid, preferably lactic acid and/or glycolic acid, especially lactic acid. is. Polylactic acid is particularly preferred in this case.

By "polylactic acid" is meant herein a polymer composed 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 suitable 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 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 S, and Resomer™ X 206 S from Boehringer Ingelheim Pharma KG (Germany).

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

In a particularly preferred embodiment, the synthetic polymer is a thermoplastic condensate based on lactic acid.

The polylactic acid used according to the invention has a preferably narrowly distributed It has a number average molecular weight (Mn) determined by gel permeation chromatography or end group titration against polystyrene standards. On the other hand, the number average molecular weight is preferably up to 1000000 g/mol, suitably up to 500000 g/mol, more preferably up to 100000 g/mol, especially up to 50000 g/mol. A number average molecular weight in the range of at least 10 000 g/mol to 500 000 g/mol has proven to be very particularly effective within the scope of the invention.

The weight average molecular weight (Mw) of preferred lactic acid polymers, especially poly-D-lactic acid, poly-L-lactic acid or poly-D,L-lactic acid, preferably measured by gel permeation chromatography against narrowly distributed polystyrene standards, is preferably in the range from 750 g/mol to 5000000 g/mol, preferably in the range from 5000 g/mol to 1000000 g/mol, particularly preferably in the range from 10000 g/mol to 500000 g/mol, especially in the range from 30000 g/mol to 500000 g/mol, The polydispersity of these polymers is more preferably in the range of 1.5-5.

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 of 0, measured in chloroform at 25° C. and a polymer concentration of 0.1%. .5 dl/g to 8.0 dl/g, preferably 0.8 dl/g to 7.0 dl/g, especially 1.5 dl/g to 3.2 dl/g.

Furthermore, particularly suitable lactic acid polymers, especially poly-D-lactic acid, poly-L-lactic acid or poly-D,L-lactic acid, measured in hexafluoro-2-propanol at 30° C. and a polymer concentration of 0.1% The intrinsic viscosity of lactic acid is in the range from 1.0 dl/g to 2.6 dl/g, especially in the range from 1.3 dl/g to 2.3 dl/g.

Furthermore, within the scope of the present invention, polymers having a glass transition temperature above 20° C., more preferably above 25° C., preferably above 30° C., particularly preferably above 35° C., especially above 40° C., in particular Thermoplastic polymers are very preferred. Within a very particularly preferred embodiment of the invention, the glass transition temperature of the polymer is in the range from 35°C to 55°C, in particular in the range from 40°C to 50°C.

Furthermore, polymers with a melting point above 50° C., more preferably at least 60° C., preferably above 150° C., particularly preferably in the range from 160° C. to 210° C., especially in the range from 175° C. to 195° C., are particularly suitable. .

In this case, the glass transition temperature and melting point of the polymer are preferably determined by differential scanning calorimetry, DSC for short. In this connection the following procedure has proven very particularly effective.

DSC measurements are performed under nitrogen on a Mettler-Toledo DSC 30S. Preferably, calibrate with indium. Preferably, measurements are made under dry, oxygen-free nitrogen (flow rate: preferably 40 ml/min). The sample weight is preferably chosen between 15 mg and 20 mg. The sample is first heated from 0° C., preferably above the melting point of the polymer to be studied, then cooled to 0° C. and a second time from 0° C. to said temperature at a heating rate of 10° C./min. heat up.

Polyesters, especially lactic acid polymers, are very particularly preferred as thermoplastic polymers.

Polymer Fibers Polymer fibers according to the invention can exist as finite fibers, eg so-called staple fibers, or as infinite fibers (filaments). The fibers are preferably present as staple fibers for better dispersibility. The length of the staple fibers mentioned above is not subject to any fundamental limitations, but is generally between 1 mm and 200 mm, preferably between 2 mm and 120 mm, particularly preferably between 2 mm and 60 mm. In particular, short fibers can be sufficiently cut from the fibers according to the invention. By short fibers is meant fiber lengths of 5 mm or less, in particular of 4 mm or less.

The individual fineness of the polymer fibers, preferably staple fibers, according to the invention is between 0.3 dtex and 30 dtex, preferably between 0.5 dtex and 13 dtex. For some applications, finenesses between 0.3 dtex and 3 dtex and fiber lengths of less than 10 mm, in particular less than 8 mm, particularly preferably less than 6 mm, particularly preferably less than 4 mm are particularly suitable.

The polymer fibers according to the invention are preferably produced from thermoplastic polymers, in particular thermoplastic organic polymers, particularly preferably thermoplastic organic polycondensates, by the melt spinning process. In this case, the polymeric material is melted in an extruder and processed through a spinneret to form polymeric fibers. The polymer fibers according to the invention generally do not comprise any fibers produced by spinning from solution, in particular by electrospinning.

Polymer fibers can also exist as bicomponent fibers consisting only of component A (core) and component B (shell). In a further embodiment, the melting point of the thermoplastic polymer in component A is at least 5°C, preferably at least 10°C, particularly preferably at least 20°C above the melting point of the thermoplastic polymer in component B. Preferably, the melting point of the thermoplastic polymer in component A is at least 100°C, preferably at least 140°C, particularly preferably at least 150°C.

The thermoplastic polymers used in the bicomponent fibers are the polymers already mentioned above.

Preparation The polymer fiber according to the present invention has carboxymethylcellulose (CMC), methylcellulose (MC), ethylcellulose (EC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), methylethylcellulose (MEC), hydroxyethylcellulose on its surface. between 0.1% and 20% by weight containing at least one cellulose ether selected from the group of methylcellulose (HEMC), hydroxypropylmethylcellulose (HPMC), ethylhydroxyethylcellulose, carboxymethylhydroxyethylcellulose and mixtures thereof , preferably from 0.5% to 3% by weight of the formulation.

In preferred embodiments, the preparation comprises carboxymethylcellulose (CMC), methylcellulose (MC), ethylcellulose (EC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), methylethylcellulose (MEC), hydroxyethylmethylcellulose (HEMC). , hydroxypropylmethylcellulose (HPMC), ethylhydroxyethylcellulose, carboxymethylhydroxyethylcellulose, at least two cellulose ethers selected from the group of carboxymethylhydroxyethylcellulose, particularly preferably prepared from methylcellulose (MC) and hydroxypropylmethylcellulose (HPMC) substances, which are present on the surface of the polymer fibers according to the invention in amounts of 0.1% to 20% by weight, preferably 0.5% to 3% by weight.

The preparations according to the invention cover at least 99% of the total surface of said fibers, preferably at least 99.5%, in particular at least 99.9%, particularly preferably 100% of the total surface of said fibers. Surface coverage is measured by microscopy. The preparation according to the invention is preferably applied only to the fibers and not to the textile fabrics subsequently produced from said fibers.

Preparations according to the invention usually have a thickness of 5 nm to 10 nm in the fibers. Thickness is measured by microscopy.

The one or more cellulose ethers used according to the invention are substances approved as additives according to EU Regulation No. 231/2012. Materials of this type are commercially available, for example as VIVAPUR™ or Methocel™.

In a preferred embodiment, the preparation contains cellulose ethers, but especially carboxymethylcellulose (CMC), methylcellulose (MC), ethylcellulose (EC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), methylethylcellulose (MEC), hydroxy Ethylmethylcellulose (HEMC), hydroxypropylmethylcellulose (HPMC), ethylhydroxyethylcellulose, carboxymethylhydroxyethylcellulose, particularly preferred are preparations of methylcellulose (MC) and hydroxypropylmethylcellulose (HPMC), the cellulose ether being .

The one or more cellulose ethers used according to the invention usually have a degree of substitution (number of substituted hydroxy groups per glucose molecule) in the range from 1.3 to 2.6, preferably from 1.6 to 2.0. have The degree of substitution is usually measured by gas chromatography.

The one or more cellulose ethers used according to the invention, but especially methylcellulose, preferably have a methoxy group proportion of 26% to 33%, especially 27% to 32%.

The hydroxypropylcellulose used according to the invention preferably has a hydroxypropyl group proportion of at most 5%.

The hydroxypropylcellulose used according to the invention preferably has a hydroxypropyl group proportion of 7% to 12%.

The one or more cellulose ethers used according to the invention, but especially methylcellulose, preferably have a methoxy group proportion of 26% to 33%, in particular 27% to 32%, and a hydroxypropyl group proportion of up to 5%.

The one or more cellulose ethers used according to the invention, but especially hydroxypropylcellulose, preferably have a methoxy group proportion of 26% to 33%, in particular 27% to 32% and a hydroxypropyl group proportion of 7% to 12%. have

The one or more cellulose ethers used according to the invention are usually between 10 000 g/mol and 380 000 g/mol, preferably between 10 000 g/mol and 200 000 g/mol, in particular between 10 000 g/mol and 100 000 g/mol, in particular It preferably has an average molecular weight Mn of between 12 000 g/mol and 60 000 g/mol, particularly preferably between 12 000 g/mol and 40 000 g/mol. Average molecular weight Mn is usually measured by gel permeation chromatography (GPC).

The one or more cellulose ethers used according to the invention usually have a degree of polymerization of 50-1000.

The one or more cellulose ethers used according to the invention are usually measured at 20° C. as a 2% by weight solution in demineralized water (demineralized water according to DIN standard EN 50272-2:2001), for example by Brookfield LVT (solution 30 seconds after the activation of (resting phase), the measurements are taken over a further 30 seconds, so that the measurements are obtained after 1 minute) have a viscosity of 10 mPas to 40 mPas.

The preparations according to the invention are usually applied as aqueous preparations, the solids content of the one or more cellulose ethers being between 0.1 g/l and 5.0 g/l. The aqueous preparations may also contain additional ingredients such as antifoam agents and the like.

The polymer fibers finished according to the invention exhibit very good fiber dispersibility in water. On the one hand, the fibers according to the invention disperse very quickly and remain dispersed for a relatively long period of time, and on the other hand the polymer fibers finished according to the invention also exhibit good storage stability, i.e. Even after storing the prepared fibers for at least 1 month (at room temperature of 25° C. and relative humidity in the range of 20% to 70%), the fibers are easily dispersed and are very stable in the form of dispersed fibers. Evenly distributed. The polymer fibers finished according to the invention are also suitable for stabilizing aqueous dispersions in which, in addition to the fibers according to the invention, solid particulate particles such as mineral particles are also present. Polymer fibers with a fineness between 0.3 dtex and 3 dtex and a fiber length of less than 10 mm, in particular less than 8 mm, particularly preferably less than 6 mm, particularly preferably less than 4 mm are suitable for this embodiment.

Furthermore, polymer fibers finished according to the invention also stabilize aqueous dispersions having other polymer fibers not finished according to the invention. Other polymer fibers that are not finished according to the present invention may be different or the same in terms of the polymer for forming the fiber. The fibers according to the invention may therefore be suitable for use in the production of wet-laid textile fabrics. Addition of the polymer fibers finished according to the invention can be carried out in a pulper or sheet former.

Polymer fibers with a fineness between 0.3 dtex and 3 dtex and a fiber length of less than 10 mm, in particular less than 8 mm, particularly preferably less than 6 mm, particularly preferably less than 4 mm are suitable for this embodiment.

Synthetic polymer fibers according to the invention are produced by conventional methods. The synthetic polymer is first optionally dried and fed to the extruder. The melted material is then spun by conventional equipment with corresponding dies. The discharge speed at the die exit area is adapted to the spinning speed such that fibers with the desired fineness are produced. Spinning speed means the speed at which the solidified yarn is taken off. The yarn so taken off may be fed directly to drawing or may be wound up and stored for drawing at a later time. The conventionally drawn fibers and filaments can then be fixed and cut to desired lengths by generally conventional methods to form staple fibers. In this case, the fibers may be uncrimped or crimped, and if crimped, the crimp must be configured for wet lamination (low crimp).

The formed fibers may have circular, elliptical and other suitable cross-sections or may have other shapes such as dumbbell-shaped, kidney-shaped, triangular or tri- or more bilobal cross-sections. Hollow fibers are also possible. Fibers formed from more than one type of polymer can also be used.

The fiber filaments thus produced are bundled to form yarns, which are then bundled to form a tow. The tow is first contained in cans for further processing. A large tow is produced by removing the tow that has been intermediately stored in the can.

These large tows, usually having 10 ktex to 600 ktex, can then be stretched using conventional methods on a conveyor line, preferably at an entry speed of 10 m/min to 110 m/min. . Formulations can now be applied, which facilitate stretching, but do not adversely affect subsequent properties.

The draw ratio preferably amounts to 1.25 to 4, in particular 2.5 to 3.5. The temperature during stretching is within the glass transition temperature of the tow to be stretched, for example between 40°C and 80°C for polyester.

Stretching can be carried out as a single stage or, if desired, using a two stage stretching process (see, for example, US Pat. No. 3,816,486). One or more chemical dressings can be applied using conventional methods before and during stretching.

For the crimping/texturing of the drawn fibres, which is optionally carried out, the customary methods of mechanical crimping using crimping machines known per se can be used. Preferred are mechanical devices for steam-assisted fiber crimping, such as stuffing boxes. However, it is also possible to use fibers crimped by other methods, thus for example three-dimensionally crimped fibers. To carry out crimping, the tow is usually first heat-treated to a temperature in the range from 50° C. to 100° C., preferably from 70° C. to 85° C., particularly preferably at about 78° C., at 1.0 bar to 6.0 bar, in particular Preferably at a pressure in the tow run-in rollers of about 2.0 bar and a pressure in the stuffing box of 0.5 bar to 6.0 bar, particularly preferably 1.5 bar to 3.0 bar, 1.0 kg/ 1.5 kg/min of steam is particularly preferred.

The formulation according to the invention is applied after drawing and before the second crimper if crimping is to be applied. The formulations according to the invention are usually heated, applied to the fibers at application temperatures in the range from 30° C. to 110° C. and dried.

It has been found that the drying of the preparation according to the invention and all post-treatments of the fibers with the preparation according to the invention are carried out at temperatures of up to 120°C. This is because higher temperatures adversely affect the dispersibility of the fibers. At temperatures of up to 120° C., a very homogeneous and uniform application of the preparation is achieved and virtually no sedimentation is observed. Such applications are advantageous due to the dispersibility according to the invention.

If smooth or optionally crimped fibers are to be relaxed and/or fixed in an oven or in a hot air stream, this is done at temperatures up to 130°C. This is because higher temperatures adversely affect the dispersibility of the fibers. At temperatures above 130° C., the application of previously obtained homogeneous and uniform preparations is impaired and the dispersibility according to the invention is reduced.

To produce staple fibers, the smooth or optionally crimped fibers are removed, cut, optionally consolidated and deposited as flocs in a compacted bale. The staple fibers of the present invention are preferably cut with a mechanical cutting device downstream of relaxation. For producing tow varieties, cutting can be omitted. These tow types are deposited in uncut form into bales and compacted.

Fibers made according to the present invention preferably have at least 2, preferably at least 3 crimps per cm (crimp arcs), preferably 3 crimp arcs per cm, in crimped embodiments. It has a crimp degree of from 3.9 bends per cm to 8.9 bends per cm, particularly preferably from 3.9 bends per cm to 8.9 bends per cm. For applications in making textile surfaces, crimp values of about 5 to 5.5 bends per cm are particularly preferred. In order to produce textile surfaces by wet lamination, the degree of crimp must be adjusted individually.

The above parameters, spinning speed, draw, draw ratio, draw temperature, fixing, fixing temperature, run-in speeds, crimping/texturing, etc., are dependent on the particular polymer. These are parameters selected within the usual ranges by those skilled in the art.

Textile fabrics can be produced from the fibers according to the invention and are also the subject of the invention. As a result of the good dispersibility of the fibers according to the invention, such textile fabrics are preferably produced by wet-lamination.

In addition to the improved dispersibility of the fibers in water, the polymer fibers according to the invention also show good pumpability of the dispersed fibers in water, so the polymer fibers according to the invention use wet-lamination processes. It is particularly suitable for the production of textile fabrics. Since the fibers according to the invention promote the dispersibility of solid particulate particles, such as mineral particles, it is also possible to produce textile fabrics with a mineral finish. Polymer fibers with a fineness between 0.3 dtex and 3 dtex and a fiber length of less than 10 mm, in particular less than 8 mm, particularly preferably less than 6 mm, particularly preferably less than 4 mm are suitable for this embodiment.

In addition to these wet lamination methods, the so-called meltblown methods (described for example in "Complete Textile Glossary", Celanese Acetate LLC, 2000 or "Chemiefaser-Lexikon", by Robert Bauer, 10th Edition, 1993). is also suitable. Such meltblown processes are suitable for the production of fine denier fibers or nonwovens, for example for hygiene applications.

Accordingly, the term "textile fabric" should be interpreted in its broadest sense within the scope of this detailed description. This may include all structures containing fibers according to the invention manufactured by a surface-forming technique. Examples of such textile fabrics are nonwovens, preferably based on staple fibers, in particular wet-laid nonwovens or nonwovens produced by the meltblowing process.

The fibers according to the invention are characterized by significantly improved dispersibility performance compared to fibers without additives according to the invention. The fibers according to the invention have very good dispersibility even after relatively long-term storage, for example weeks or months, in the form of bales or similar structures.

Furthermore, the fibers according to the invention exhibit improved long-term dispersion. That is, when fibers according to the invention are dispersed in a liquid medium, such as water, the fibers remain dispersed for a longer period of time and only begin to settle after a relatively long period of time.

Furthermore, the fibers according to the present invention exhibit reduced fiber shedding, resulting in improvements in occupational injury prevention. This is because the preparations mentioned lead to a significantly increased retention in fiber composites. A reduction in fiber shedding is very important, especially in the formation of textile fabrics, such as nonwoven fabrics.

Textile fabrics produced with the fibers according to the invention are in particular wet-laid textile fabrics, in particular wet-laid nonwovens.

Textile fabrics produced from the fibers according to the invention contain the polymers according to the invention and on the surface thereof carboxymethylcellulose (CMC), methylcellulose (MC), ethylcellulose (EC), hydroxyethylcellulose (HEC), hydroxypropylcellulose ( at least one cellulose ether selected from the group of HPC), methylethylcellulose (MEC), hydroxyethylmethylcellulose (HEMC), hydroxypropylmethylcellulose (HPMC), ethylhydroxyethylcellulose, carboxymethylhydroxyethylcellulose and mixtures thereof; Between 0.1% and 20% by weight, preferably between 0.5% and 3% by weight of the formulation are applied. The proportion of the polymer fibers according to the invention in the textile fabric is usually at least 10% by weight, preferably at least 20% by weight, in particular at least 30% by weight, particularly preferably at least 50% by weight, relative to the total weight of the textile fabric. In a particularly preferred embodiment, the textile fabric consists exclusively of polymer fibers according to the invention.

Test method:
Unless already indicated in the detailed description above, the following measurement and test methods are used:

Fineness:
The fineness was measured according to DIN EN ISO1973.

Dispersibility:
To assess dispersibility, the following test method was developed and used by the present invention.

Fibers according to the invention are cut to lengths between 2 mm and 12 mm. The cut fibers were introduced at room temperature (25° C.) into a glass container (dimensions: length 150 mm, width 200 mm, height 200 mm) filled with demineralized water (demineralized=completely demineralized). The amount of fiber is 0.25 g per liter of demineralized water. For improved evaluation, 1 g of fiber and 4 liters of demineralized water are commonly used.

The fiber/demineralized water mixture is then stirred by a conventional laboratory magnetic stirrer (e.g. IKAMAG RCT) and a magnetic stirring bar (80 mm) for at least 3 minutes (rotational speed ranging from 750 rpm to 1500 rpm) and turn off the switch. It is then evaluated whether all fibers are dispersed.

Fiber dispersion behavior was evaluated as follows:
Not distributed (-)
Partially distributed (○)
Fully distributed (+)

The above evaluations were performed after defined time intervals.

As a comparison, fibers were used which did not contain the preparation according to the invention, but were otherwise identical.

Gelling temperature:
The gel temperature was measured by an oscillating rheometer, model Physica MCR 301, manufactured by Anton Paar.

Unless already specified in the detailed description above, the other parameters below are measured according to the publication "Methylcellulose, a Cellulose Derivative with Original Physical Properties and Extended Applications" in Polymers 2015, 7(5), 777-803 Or measured by the test method.

The invention is illustrated by the following examples, which are not intended to limit the scope of the invention.

The methylcellulose solution was applied to the melt-spun PLA fibers on a conveyor line during processing and then dried. The PLA fibers produced thus have on their surface a formulation comprising at least one methylcellulose (MC).

The PLA fibers produced contain the preparation according to the invention on at least 99% of the total surface of the fibers.

PLA fibers according to the invention were cut into 6 mm lengths, 1 gram of chopped PLA fibers was dispersed and tested at room temperature (25° C.) as described above.

For comparison, 1 gram of PLA fibers without the additive according to the invention, but otherwise identical, were dispersed and tested at room temperature (25° C.) as described above.

The fibers according to the invention show significantly improved dispersibility performance after several weeks of storage, along with greatly improved long-term dispersion relative to the comparative fibers (without finishing according to the invention).

Claims (24)

A polymer fiber comprising at least one synthetic polymer,
said fibers having, on their surface, carboxymethylcellulose (CMC), methylcellulose (MC), ethylcellulose (EC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), methylethylcellulose (MEC), hydroxyethylmethylcellulose (HEMC), a preparation comprising at least one cellulose ether selected from the group of hydroxypropylmethylcellulose (HPMC), ethylhydroxyethylcellulose, carboxymethylhydroxyethylcellulose and mixtures thereof;
the cellulose ether has a gelation temperature in the range of 45 °C to 70 °C;
Polymer fiber, characterized in that said preparation has a thickness of 5 nm to 10 nm, and said preparation covers at least 99.9% of the total surface of said fiber. Polymer fiber according to claim 1, characterized in that the synthetic polymer is a thermoplastic polymer, preferably a thermoplastic polycondensate, in particular a thermoplastic polycondensate based on biopolymers. Said synthetic polymers include acrylonitrile ethylene propylene (diene) styrene copolymers, acrylonitrile methacrylate copolymers, acrylonitrile methyl methacrylate copolymers, acrylonitrile chlorinated polyethylene styrene copolymers, acrylonitrile butadiene styrene copolymers, acrylonitrile ethylene propylene styrene copolymers, aromatic polyesters, acrylonitrile styrene acryloesters. Copolymer, butadiene styrene copolymer, cellulose acetate, cellulose acetobutyrate, cellulose acetopropionate, cellulose hydrate, carboxymethyl cellulose, cellulose nitrate, cellulose propionate, cellulose triacetate, polyvinyl chloride, ethylene acrylic acid copolymer, ethylene butyl acrylate Copolymer, ethylene chlorotrifluoroethylene copolymer, ethylene ethyl acrylate copolymer, ethylene methacrylate copolymer, ethylene methacrylic acid copolymer, ethylene tetrafluoroethylene copolymer, ethylene vinyl alcohol copolymer, ethylene butene copolymer, ethyl cellulose, polystyrene, polyfluoroethylene propylene, methyl methacrylate acrylonitrile butadiene styrene copolymer, methyl methacrylate butadiene styrene copolymer, methyl cellulose, polyamide 11, polyamide 12, polyamide 46, polyamide 6, polyamide 6-3-T, polyamide 6-terephthalic acid copolymer, polyamide 66, polyamide 69, polyamide 610, polyamide 612, Polyamide 6I, Polyamide MXD 6, Polyamide PDA-T, Polyamide, Polyarylether, Polyaryletherketone, Polyamideimide, Polyarylamide, Polyamino-bis-maleimide, Polyarylate, Polybutene-1, Polybutylacrylate, Polybenzo Imidazole, poly-bis-maleimide, polyoxadiazobenzimidazole, polybutylene terephthalate, polycarbonate, polychlorotrifluoroethylene, polyethylene, polyester carbonate, polyaryletherketone, polyetheretherketone, polyetherimide, polyetherketone, poly Ethylene oxide, polyaryl ether sulfone, polyethylene terephthalate, polyimide, polyisobutylene, polyiso Cyanurate, polyimide sulfone, polymethacrylimide, polymethacrylate, poly-4-methylpentene-1, polyacetal, polypropylene, polyphenylene oxide, polypropylene oxide, polyphenylene sulfide, polyphenylene sulfone, polystyrene, polysulfone, polytetrafluoroethylene, polyurethane, polyacetic acid Vinyl, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinylidene chloride, polyvinylidene fluoride, polyvinyl fluoride, polyvinyl methyl ether, polyvinylpyrrolidone, styrene butadiene copolymer, styrene isoprene copolymer, styrene maleic anhydride copolymer, styrene maleic anhydride butadiene copolymers, styrene methyl methacrylate copolymers, styrene methyl styrene copolymers, styrene acrylonitrile copolymers, vinyl chloride ethylene copolymers, vinyl chloride methacrylate copolymers, vinyl chloride maleic anhydride copolymers, vinyl chloride maleimide copolymers, vinyl chloride methyl methacrylate copolymers, vinyl chloride octyl acrylate copolymers, 2. A polymer fiber according to claim 1, characterized in that it is selected from the group of polymers comprising vinyl chloride vinyl acetate copolymers, vinyl chloride vinylidene chloride copolymers, and vinyl chloride vinylidene chloride acrylonitrile copolymers. 2. The polymer fiber of claim 1, wherein said synthetic polymer is polyester. Polymer fiber according to claim 1, characterized in that the synthetic polymer is a synthetic biopolymer, preferably a synthetic biopolymer from polylactic acid. Said polylactic acid is characterized in that it has a number average molecular weight (Mn) of at least 500 g/mol, preferably of at least 1000 g/mol, particularly preferably of at least 5000 g/mol, suitably of at least 10000 g/mol, especially of at least 25000 g/mol. The polymer fiber of claim 5, wherein 7. Claim 5 or 6, characterized in that the polylactic acid has a number average molecular weight (Mn) of max. 1000000 g/mol, preferably max. The polymer fiber according to . Said polylactic acid is in the range from 750 g/mol to 5000000 g/mol, preferably in the range from 5000 g/mol to 1000000 g/mol, particularly preferably in the range from 10000 g/mol to 500000 g/mol, especially in the range from 30000 g/mol to 500000 g/mol. Polymer fiber according to any one of claims 5 to 7, characterized in that it has a weight average molecular weight (Mw) of Polymer fiber according to any one of claims 5 to 8, characterized in that said polylactic acid has a polydispersity in the range of 1.5-5. Polymer fiber according to any one of claims 5 to 9, characterized in that said polylactic acid is poly-D-lactic acid, poly-L-lactic acid or poly-D,L-lactic acid. Polymer fibers according to any one of the preceding claims, characterized in that the fibers are present in the form of staple fibers, preferably staple fibers having a length in the range from 1 mm to 200 mm. Polymer fiber according to any one of the preceding claims, characterized in that said fiber has a fineness between 0.3 dtex and 30 dtex, preferably between 0.5 dtex and 13 dtex. Said fibers are bicomponent fibers consisting only of component A (core) and component B (shell), the melting point of component A being at least 5°C, preferably at least 10°C, particularly preferably at least 20°C, above the melting point of component B. 13. The polymer fiber according to any one of claims 1 to 12, characterized in that the temperature is high. of claims 1 to 13, characterized in that between 0.1% and 20% by weight, preferably 0.5% to 3% by weight, of said preparation is applied to the surface of said fibers. A polymer fiber according to any one of the preceding claims. Said preparations are carboxymethylcellulose (CMC), methylcellulose (MC), ethylcellulose (EC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), methylethylcellulose (MEC), hydroxyethylmethylcellulose (HEMC), hydroxypropylmethylcellulose (HPMC), ethyl hydroxyethyl cellulose, carboxymethyl hydroxyethyl cellulose, and particularly preferred are preparations from methyl cellulose (MC) and hydroxypropylmethyl cellulose (HPMC). Polymer fiber according to any one of claims 1 to 14, characterized in that. Polymer fiber according to any one of the preceding claims, characterized in that the preparation covers 100% of the total surface of the fiber. Polymer according to any one of the preceding claims, characterized in that the cellulose ether has a gelling temperature in the range from 45 °C to 60°C, particularly preferably in the range from 45°C to 55°C. fiber. Claim 1, characterized in that the cellulose ether has a degree of substitution (number of substituted hydroxy groups per glucose molecule) in the range from 1.3 to 2.6, preferably from 1.6 to 2.0. 18. The polymer fiber of any one of claims 1-17. Polymer fiber according to any one of the preceding claims, characterized in that the cellulose ether is methylcellulose with a methoxy group proportion of preferably 26% to 33%, in particular 27% to 32%. 19. Any one of claims 1 to 18, characterized in that the cellulose ether is hydroxypropylcellulose with a hydroxypropyl group proportion of preferably at most 5%, particularly preferably with a hydroxypropyl group proportion of 7% to 12%. A polymer fiber according to claim 1. 19. The cellulose ether according to any one of claims 1 to 18, characterized in that it has a methoxy group proportion of 26% to 33%, in particular 27% to 32%, and a hydroxypropyl group proportion of up to 5%. polymer fibers. 19. The cellulose ether according to any one of claims 1 to 18, characterized in that it has a methoxy group proportion of 26% to 33%, in particular 27% to 32%, and a hydroxypropyl group proportion of 7% to 12%. The polymer fiber according to . A textile fabric, in particular obtainable by a wet-lamination process, containing polymer fibers as defined in any one of claims 1-22. Use of polymer fibers as defined in any one of claims 1 to 22 for the production of aqueous suspensions.