DE102005001200A1 - Process for the preparation of thermoplastic polyurethane particles - Google Patents

Abstract

Process for the preparation of thermoplastic polyurethane particles, characterized in that molten thermoplastic polyurethane is dripped.

Description

The The invention relates to processes for the preparation of preferably round thermoplastic polyurethane particles, preferably based on aliphatic isocyanates, more preferably hexamethylene diisocyanate, preferably with a melt index according to DIN ISO 1133 (180 ° C / 2.16 kg) between 5 g / 10 min and 300 g / 10 min, more preferably between 10 g / 10min and 200 g / 10min, in particular between 15 g / 10min and 200 g / 10 min, preferably a flowability according to DIN EN ISO 6186: 1998 of less than 15 sec / 100g, preferably less than 10 sec / 100g and preferably a particle diameter of the powder is preferably smaller 2000 μm, more preferably between 50 microns and 1000 μm in particular between 100 μm and 900 μm. The particle diameter is the maximum diameter of a TPU particle in the powder, the average particle diameter is preferred in the powder. Furthermore, the invention relates to such available thermoplastic Polyurethane particles and process for the production of articles based on thermoplastic polyurethanes by sintering powdered thermoplastic polyurethanes, wherein as powdered thermoplastic polyurethanes obtainable according to the invention thermoplastic Polyurethane particles used. Under the term "round" are in this writing To understand shapes that have no corners or edges. there may be droplet-shaped, globular or other forms that accept a drop in falling can.

thermoplastic Plastics are plastics that, when it comes in for the material for processing and application typical temperature range repeatedly heated and chilled will remain thermoplastic. Under thermoplastic the property becomes understood a plastic, in a typical temperature range for him repeated in the heat to soften and cool down to harden and in the softened state repeated by flowing as a molded part, extrudate or forming part to form semi-finished products or articles. thermoplastic Plastics are widely used in the art and are found in the form of fibers, sheets, films, moldings, bottles, casings, Packaging, etc. Thermoplastic polyurethane (hereinafter referred to as TPU) is an elastomer used in many applications finds, for. As shoe applications, films, fibers, ski boots, hoses.

The Production of the TPU is usually done discontinuously or continuously by the known methods, for example with reaction extruders or the belt method One-shot or prepolymer process. In these methods, the reacting components, in particular diisocyanate and Diol successively or simultaneously mixed together, wherein the reaction starts immediately. In the extruder process the starting components individually or as a mixture in the extruder introduced, z. B. at temperatures of 100 to 280 ° C, preferably 140 to 250 ° C for the reaction brought, the resulting TPU is extruded, cooled and granulated.

The Products that can be accessed using these known methods must be a granulation usually especially crushed for use in powder slush, z. B. be ground to achieve an acceptable particle size. Usually the granules are ground (cryogenically) at low temperatures. The powders then obtained contain irregular and angular particles, the the flowability influence negatively. For However, certain applications require TPU particles one possible pronounced flowability exhibit. This is especially true in the well-known powder-slush. In this process, powdered TPU is usually in a mold on a surface distributed, which heated up a melting of the TPU powder and thus producing a TPU "skin" is added If this method uses a mold, one is possible fast and complete Distribution of TPU powder on the surface desirable. This is, however can only be achieved if the flowability of the TPU powder is sufficient is high.

task Thus, the present invention was to provide methods of preparation of thermoplastic polyurethane particles and thermoplastic available in this way To develop polyurethane particles that have a high flowability feature, one possible have round shape and in particular in the powder-slush process a fast and complete Covering the surface enable.

These tasks could be solved by dropping molten thermoplastic polyurethane. For the purposes of this invention, the expression "dripping" also means "spraying". Especially the round TPU according to the invention are very suitable for powder-slush processing, since they are very easy flowing due to their round shape and therefore can be easily and quickly applied in the mold and fill it well. So far, ground TPU are used in the powder-slush, which, however, due to the grinding process have a non-optimal flowability and therefore in the powder-slush application an improvement potential exhibit.

The Injection according to the invention can be made by well-known methods and apparatuses for spraying or Dripping of liquids respectively. Corresponding methods are described, inter alia for melted Polyester in WO 02/18113. Details of process parameters, too Contents of this document are also given in WO 01/64326, Page 12 to page 14 and in DE-A 101 37 925, page 7, lines 13 to 39, in particular lines 24 to 39.

The Generation of the spray or the droplets by spraying and / or dripping of the molten TPU can by means of common devices for spraying or dripping liquids done, for example by means of spray nozzles, Vibrvertvertropfern and vibrating diaphragm aerosol generators.

The inventive method may preferably be such that the molten thermoplastic Polyurethane dripped to drips by means of a dropper nozzle, especially preferably by the molten thermoplastic polyurethane by means of a vibrated perforated disc, the preferred a frequency between 50 and 20,000 Hz, more preferably between 70 and 5000 Hz, dripped.

The Temperature of the molten TPU upon spraying and / or dripping is preferred between 140 and 260 ° C, more preferably between 160 and 220 ° C.

Of the when spraying adjusting droplet diameter is preferred according to the invention less than 2000 μm, more preferably less than 1200 μm, in particular between 50 microns up to 1200 μm.

The Dripping and / or spraying is preferably carried out in apparatuses that are also suitable for spray drying are suitable. Such reactors are described, for example, in K. Masters, Spray Drying Handbook, 5th Edition, Longman, 1991, pages 23 to 66, described.

The process according to the invention is preferably carried out in apparatuses in which the spray droplets can fall freely. Suitable for this purpose are apparatuses, as for example in the patent specification US 5,269,980 described.

Prefers Reactors are used, the spray droplets due to their height Provide minimum residence time before the droplets z. B. on the floor of the reactor. Preference is thus given to the molten drip thermoplastic polyurethane into a spray tower. It points the spray tower preferably a height between 2 m and 30 m. Particularly preferred is the device for spraying and / or dripping the TPU at least at an altitude between 2.6 m and 12 m from the bottom of the drop tower. After spraying the Mix at this altitude into the reaction space of the spray or the drops can be driven fall by gravity towards the bottom of the drop tower. Prefers you drip or spray the TPU at the head of the drop tower.

Prefers can in the fall tower in the vertical direction, i. dependent on its height, a temperature profile, particularly preferably a falling down Temperature present.

Prefers At the bottom of the drop tower, a fluidized bed may be present. Fluidized bed reactors are especially for Reactions with solids are well known. This fluidized bed offers the advantage that the addition of liquid and / or solid additives (eg flame retardants, color pigments, etc.) is possible. Preference is thus given to above and / or in the fluidized bed the liquid and / or solid drops of additive (s).

Of the Falling tower is preferred by an inert gas, i. especially one Fabric chosen at the Temperature and the pressure in the reactor in the gaseous state is present and across from Isocyanates are inert, particularly preferably nitrogen, flows through. Prefers is the Gleichstromfahrweise, that is, the inert gas flows through the reactor from top to bottom. The inert gas velocity is preferably adjusted so that the flow in the reactor is preferably laminar and is preferably 0.02 to 1.5 m / s, preferably 0.05 to 0.4 m / s.

The obtainable by the process according to the invention TPU particles are usually in powdered form before and can collected in this form, for example, at the bottom of the reactor and after well known methods, e.g. B. removed by means of screw conveyor, if necessary be tempered and processed, for. B. by extrusion or Injection molding.

The thermoplastic polyurethane is dripped or sprayed in a molten state according to the invention. In this case, the TPU z. B. may be in granulated form, are melted in the Vertropfungsapparatur. Preferably, however, the TPU is introduced in a molten state from an extruder into a dropper device. The extruder may be both a reaction extruder in which the TPU is synthesized and an extruder, which is fed with granulated TPU, which may optionally come directly from a belt plant.

Processes for the production of thermoplastic polyurethanes, also referred to in this document as TPU, are well known. In general, TPUs are prepared by reacting (a) isocyanates with (b) isocyanate-reactive compounds, usually having a molecular weight (M _w ) of 500 to 10,000, preferably 500 to 5000, more preferably 800 to 3000 and (c) chain extenders having a Molecular weight of 50 to 499 optionally prepared in the presence of (d) catalysts and / or (e) conventional additives.

• a) Als organische Isocyanate (a) können allgemein bekannte aliphatische, cycloaliphatische, araliphatische und/oder aromatische Isocyanate eingesetzt werden, beispielsweise Tri-, Tetra-, Penta-, Hexa-, Hepta- und/oder Oktamethylendiisocyanat, 2-Methyl-pentamethylen-diisocyanat-1,5, 2-Ethyl-butylen-diisocyanat-1,4, Pentamethylen-diisocyanat-1,5, Butylen-diisocyanat-1,4, 1-Isocyanato-3,3,5-trimethyl-5-isocyanato-methyl-cyclohexan (Isophoron-diisocyanat, IPDI), 1,4- und/oder 1,3-Bis(isocyanatomethyl)cyclohexan (HXDI), 1,4-Cyclohexan-diisocyanat, 1-Methyl-2,4- und/oder -2,6-cyclohexan-di-isocyanat und/oder 4,4'-, 2,4'- und 2,2'-Dicyclohexylmethan-diisocyanat, 2,2'-, 2,4'- und/oder 4,4'-Diphenylmethandiisocyanat (MDI), 1,5-Naphthylendiisocyanat (NDI), 2,4- und/oder 2,6-Toluylendiisocyanat (TDI), Diphenylmethandiisocyanat, 3,3'-Dimethyl-diphenyl-diisocyanat, 1,2-Diphenylethandiisocyanat und/oder Phenylendiisocyanat. Bevorzugt wird 4,4'-MDI verwendet. Für powder-slush-Anwendungen sind, wie eingangs dargestellt auch aliphatische Isocyanate bevorzugt, besonders bevorzugt 1-Isocyanato-3,3,5-trimethyl-5-isocyanato-methylcyclohexan (Isophoron-diisocyanat, IPDI) und/oder Hexamethylendiisocyanat (HDI), insbesondere Hexamethylendiisocyanat. Wie bereits eingangs dargestellt können als Isocyanat (a) auch Prepolymer eingesetzt werden, die frei Isocyanatgruppen aufweisen. Der NCO-Gehalt dieser Prepolymere beträgt bevorzugt zwischen 10 und 25 %. Die Prepolymere können den Vorteil bieten, dass aufgrund der Vorreaktion bei der Herstellung der Prepolymere eine geringere Reaktionszeit bei der Herstellung der TPU benötigt wird.
• b) Als gegenüber Isocyanaten reaktive Verbindungen (b) können die allgemein bekannten gegenüber Isocyanaten reaktiven Verbindungen eingesetzt werden, beispielsweise Polyesterole, Polyetherole und/oder Polycarbonatdiole, die üblicherweise auch unter dem Begriff "Polyole" zusammengefasst werden, mit Molekulargewichten zwischen 500 und 8000, bevorzugt 600 bis 6000, insbesondere 800 bis weniger als 3000, und bevorzugt einer mittleren Funktionalität gegenüber Isocyanaten von 1,8 bis 2,3, bevorzugt 1,9 bis 2,2, insbesondere 2. Bevorzugt setzt man Polyetherpolyole ein, beispielsweise solche auf der Basis von allgemein bekannten Startersubstanzen und üblichen Alkylenoxiden, beispielsweise Ethylenoxid, Propylenoxid und/oder Butylenoxid, bevorzugt Polyetherole basierend auf Propylenoxid-1,2 und Ethylenoxid und insbesondere Polyoxytetramethylen-glykole. Die Polyetherole weisen den Vorteil auf, dass sie eine höhere Hydrolysestabilität als Polyesterole besitzen.

In the following, by way of example, the starting components and processes for the preparation of the preferred polyurethanes are shown. The components (a), (b), (c) and optionally (d) and / or (e) usually used in the preparation of the polyurethanes are described below by way of example:

• a) As organic isocyanates (a) it is possible to use generally known aliphatic, cycloaliphatic, araliphatic and / or aromatic isocyanates, for example tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene diisocyanate, 2-methylpentamethylene diisocyanate-1,5, 2-ethyl-butylene-diisocyanate-1,4, pentamethylene-diisocyanate-1,5, butylene-diisocyanate-1,4, 1-isocyanato-3,3,5-trimethyl-5-isocyanato methylcyclohexane (isophorone diisocyanate, IPDI), 1,4- and / or 1,3-bis (isocyanatomethyl) cyclohexane (HXDI), 1,4-cyclohexane diisocyanate, 1-methyl-2,4- and / or 2,6-cyclohexane diisocyanate and / or 4,4'-, 2,4'- and 2,2'-dicyclohexylmethane diisocyanate, 2,2'-, 2,4'- and / or 4, 4'-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate (NDI), 2,4- and / or 2,6-toluene diisocyanate (TDI), diphenylmethane diisocyanate, 3,3'-dimethyl-diphenyl-diisocyanate, 1,2- Diphenylethane diisocyanate and / or phenylene diisocyanate. Preferably, 4,4'-MDI is used. For powder slush applications, aliphatic isocyanates are also preferred, particularly preferably 1-isocyanato-3,3,5-trimethyl-5-isocyanato-methylcyclohexane (isophorone diisocyanate, IPDI) and / or hexamethylene diisocyanate (HDI), in particular hexamethylene diisocyanate. As already mentioned, prepolymers which have free isocyanate groups can also be used as the isocyanate (a). The NCO content of these prepolymers is preferably between 10 and 25%. The prepolymers can offer the advantage that, due to the pre-reaction in the preparation of the prepolymers, a shorter reaction time is required in the production of the TPU.
• b) As isocyanate-reactive compounds (b) it is possible to use the generally known isocyanate-reactive compounds, for example polyesterols, polyetherols and / or polycarbonatediols, which are usually also grouped under the term "polyols", with molecular weights between 500 and 8000 600 to 6000, in particular 800 to less than 3000, and preferably an average functionality over isocyanates of 1.8 to 2.3, preferably 1.9 to 2.2, in particular 2. Preference is given to using polyether polyols, for example those based on of generally known starter substances and customary alkylene oxides, for example ethylene oxide, propylene oxide and / or butylene oxide, preferably polyetherols based on propylene oxide-1,2 and ethylene oxide and in particular polyoxytetramethylene glycols. The polyetherols have the advantage that they have a higher hydrolysis stability than polyesterols.

Farther can as polyetherols so-called low-unsaturated polyetherols can be used. Under low unsaturated Polyols are in the context of this invention, in particular polyether alcohols with a content of unsaturated Compounds of less than 0.02 meg / g, preferably less than 0.01 meg / g, understood.

such Polyether alcohols are usually by addition of alkylene oxides, in particular ethylene oxide, propylene oxide and mixtures thereof the diols or triols described above in the presence of highly active Catalysts produced. Such highly active catalysts are for example, cesium hydroxide and multimetal cyanide catalysts, also referred to as DMC catalysts. One often used DMC catalyst is the zinc hexacyanocobaltate. Of the DMC catalyst can be left in the polyether alcohol after the reaction, usually it is removed, for example by sedimentation or filtration.

Farther can Polybutadienediols having a molecular weight of 500-10000 g / mol preferably 1000-5000 g / mol, in particular 2000-3000 g / mol. TPU's which under the Use of these polyols can be prepared by thermoplastic Processing radiation crosslinked. This leads z. B. to a better Burning behavior.

• c) Als Kettenverlängerungsmittel (c) können allgemein bekannte aliphatische, araliphatische, aromatische und/oder cycloaliphatische Verbindungen mit einem Molekulargewicht von 50 bis 499, bevorzugt 2-funktionelle Verbindungen, eingesetzt werden, beispielsweise Diamine und/oder Alkandiole mit 2 bis 10 C-Atomen im Alkylenrest, insbesondere 1,3-Propandiol, Butandiol-1,4, Hexandiol-1,6 und/oder Di-, Tri-, Tetra-, Penta-, Hexa-, Hepta-, Okta-, Nona- und/oder Dekaalkylenglykole mit 3 bis 8 Kohlenstoffatomen, bevorzugt entsprechende Oligo- und/oder Polypropylenglykole, wobei auch Mischungen der Kettenverlängerer eingesetzt werden können.

Instead of a polyol, it is also possible to use mixtures of different polyols.

• c) As chain extenders (c) it is possible to use generally known aliphatic, araliphatic, aromatic and / or cycloaliphatic compounds having a molecular weight of 50 to 499, preferably 2-functional compounds, for example diamines and / or alkanediols having 2 to 10 carbon atoms in the alkylene radical, in particular 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and / or di-, tri-, tetra-, penta-, hexa-, hepta-, octa, nona and / or decaalkylene glycols with 3 to 8 carbon atoms, preferably corresponding oligo- and / or polypropylene glycols, it also being possible to use mixtures of the chain extenders.

• d) Geeignete Katalysatoren, welche insbesondere die Reaktion zwischen den NCO-Gruppen der Diisocyanate (a) und den Hydroxylgruppen der Aufbaukomponenten (b) und (c) beschleunigen, sind die nach dem Stand der Technik bekannten und üblichen tertiären Amine, wie z. B. Triethylamin, Dimethylcyclohexylamin, N-Methylmorpholin, N,N'-Dimethylpiperazin, 2-(Dimethylamino ethoxy)-ethanol, Diazabicyclo-(2,2,2)-octan und ähnliche sowie insbesondere organische Metallverbindungen wie Titansäureester, Eisenverbindungen wie z. B. Eisen-(III)-acetylacetonat, Zinnverbindungen, z.B. Zinndiacetat, Zinndioctoat, Zinndilaurat oder die Zinndialkylsalze aliphatischer Carbonsäuren wie Dibutylzinndiacetat, Dibutylzinndilaurat oder ähnliche. Die Katalysatoren werden üblicherweise in Mengen von 0,0001 bis 0,1 Gew.-Teilen pro 100 Gew.-Teile Polyhydroxylverbindung (b) eingesetzt.
• e) Neben Katalysatoren (d) können den Aufbaukomponenten (a) bis (c) auch übliche Hilfsmittel und/oder Zusatzstoffe (e) hinzugefügt werden. Genannt seien beispielsweise Treibmittel, oberflächenaktive Substanzen, Füllstoffe, Keimbildungsmittel, Gleit- und Entformungshilfen, Farbstoffe und Pigmente, Antioxidantien, z. B. gegen Hydrolyse, Licht, Hitze oder Verfärbung, anorganische und/oder organische Füllstoffe, Flammschutzmittel, Verstärkungsmittel und Weichmacher, Metalldeaktivatoren. In einer bevorzugten Ausführungsform fallen unter die Komponente (e) auch Hydrolyseschutzmittel wie beispielsweise polymere und niedermolekulare Carbodiimide. Besonders bevorzugt enthält das thermoplastische Polyurethan in den erfindungsgemäßen Materialien Melamincyanurat, das als Flammschutzmittel wirkt. Bevorzugt wird Melamincyanurat in einer Menge zwischen 0,1 und 60 Gew.-%, besonders bevorzugt zwischen 5 und 40 Gew.-%, insbesondere zwischen 15 und 25 Gew.-% eingesetzt, jeweils bezogen auf das Gesamtgewicht des TPU. Bevorzugt enthält das thermoplastische Polyurethan Triazol und/oder Triazolderivat und Antioxidantien in einer Menge von 0,1 bis 5 Gew.-% bezogen auf das Gesamtgewicht des thermoplastischen Polyurethans. Als Antioxidantien sind im allgemeinen Stoffe geeignet, welche unerwünschte oxidative Prozesse im zu schützenden Kunststoff hemmen oder verhindern. Im allgemeinen sind Antioxidantien kommerziell erhältlich. Beispiele für Antioxidantien sind sterisch gehinderte Phenole, aromatische Amine, Thiosynergisten, Organophosphorverbindungen des trivalenten Phosphors, und Hindered Amine Light Stabilizers. Beispiele für Sterisch gehinderte Phenole finden sich in Plastics Additive Handbook, 5^th edition, H. Zweifel, ed, Hanser Publishers, München, 2001 ([1]), S.98-107 und S.116-121. Beispiele für Aromatische Amine finden sich in [1] S.107-108. Beispiele für Thiosynergisten sind gegeben in [1], S.104-105 und S.112-113. Beispiele für Phosphite finden sich in [1], S.109-112. Beispiele für Hindered Amine Light Stabilizer sind gegeben in [1], S.123-136. Zur Verwendung im erfindungsgemäßem Antioxidantiengemisch eignen sich bevorzugt phenolische Antioxidantien. In einer bevorzugten Ausführungsform weisen die Antioxidantien, insbesondere die phenolischen Antioxidantien, eine Molmasse von größer 350 g/mol, besonders bevorzugt von größer 700g/mol und einer maximalen Molmasse < 10000 g/mol bevorzugt < 3000 g/mol auf. Ferner besitzen sie bevorzugt einen Schmelzpunkt von kleiner 180°C. Weiterhin werden bevorzugt Antioxidantien verwendet, die amorph oder flüssig sind.

The components a) to c) are particularly preferably difunctional compounds, ie diisocyanates (a), difunctional polyols, preferably polyetherols (b) and difunctional chain extenders, preferably diols.

• d) Suitable catalysts which in particular accelerate the reaction between the NCO groups of the diisocyanates (a) and the hydroxyl groups of the synthesis components (b) and (c) are known and customary in the prior art tertiary amines, such as. As triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N, N'-dimethylpiperazine, 2- (dimethylamino ethoxy) ethanol, diazabicyclo- (2,2,2) octane and the like, and in particular organic metal compounds such as titanic acid esters, iron compounds such. As iron (III) acetylacetonate, tin compounds, such as tin diacetate, tin dioctoate, tin dilaurate or Zinndialkylsalze aliphatic carboxylic acids such as dibutyltin diacetate, dibutyltin dilaurate or the like. The catalysts are usually used in amounts of 0.0001 to 0.1 parts by weight per 100 parts by weight of polyhydroxyl compound (b).
• e) In addition to catalysts (d) can the constitutional components (a) to (c) and conventional auxiliaries and / or additives (e) are added. Mention may be made, for example, blowing agents, surface-active substances, fillers, nucleating agents, lubricants and mold release agents, dyes and pigments, antioxidants, eg. As against hydrolysis, light, heat or discoloration, inorganic and / or organic fillers, flame retardants, reinforcing agents and plasticizers, metal deactivators. In a preferred embodiment, component (e) also includes hydrolysis protectants such as, for example, polymeric and low molecular weight carbodiimides. The thermoplastic polyurethane in the materials according to the invention particularly preferably contains melamine cyanurate, which acts as a flame retardant. Melamine cyanurate is preferably used in an amount of between 0.1 and 60% by weight, more preferably between 5 and 40% by weight, in particular between 15 and 25% by weight, in each case based on the total weight of the TPU. Preferably, the thermoplastic polyurethane contains triazole and / or triazole derivative and antioxidants in an amount of 0.1 to 5 wt .-% based on the total weight of the thermoplastic polyurethane. As antioxidants are generally suitable substances which inhibit or prevent unwanted oxidative processes in the plastic to be protected. In general, antioxidants are commercially available. Examples of antioxidants are hindered phenols, aromatic amines, thiosynergists, trivalent phosphorus organophosphorus compounds, and hindered amine light stabilizers. Examples of sterically hindered phenols are found in Plastics Additives Handbook, ^th edition 5, H. Zweifel, ed, Hanser Publishers, Munich, 2001 ([1]), and S.98-107 S.116-121. Examples of aromatic amines can be found in [1] p.107-108. Examples of thiosynergists are given in [1], p.104-105 and p.112-113. Examples of phosphites can be found in [1], p.109-112. Examples of hindered amine light stabilizers are given in [1], p.123-136. Phenolic antioxidants are preferred for use in the antioxidant mixture according to the invention. In a preferred embodiment, the antioxidants, in particular the phenolic antioxidants, have a molecular weight of greater than 350 g / mol, more preferably greater than 700 g / mol and a maximum molecular weight of <10,000 g / mol, preferably <3,000 g / mol. Furthermore, they preferably have a melting point of less than 180 ° C. Furthermore, antioxidants are preferably used which are amorphous or liquid.

Next the said components a), b) and c) and optionally d) and e) can also chain regulator, usually having a molecular weight of 31 to 3000, are used. Such chain regulator are compounds which are only a functional isocyanate-reactive Group have such. B. monofunctional alcohols, monofunctional Amines and / or monofunctional polyols. By such chain regulator can a flow behavior, especially with TPUs, can be set specifically. chain regulators can generally in an amount of 0 to 5, preferably 0.1 to 1 parts by weight, based are used and fall on 100 parts by weight of component b) by definition the component (c).

All The molecular weights stated in this document have the unit [g / mol].

to Adjustment of hardness The TPUs can be the Construction components (b) and (c) in relatively broad molar ratios be varied. proven have molar ratios of component (b) to total chain extenders to be used (c) from 10: 1 to 1:10, especially from 1: 1 to 1: 4, wherein the hardness the TPU increases with increasing content of (c).

Can use the thermoplastic polyurethane particles according to the invention for extrusion, injection molding, calendar articles so as especially for powder-slush find.

The Processing of the invention produced TPUs which are preferred according to the invention in powder form, in the powder-slush process or in injection molding, Calendar and extrusion articles, e.g. B. to the desired Films, molded parts, rolls, fibers, linings in automobiles, hoses, cable connectors, bellows, Tow cables, cable sheathing, seals, belts or damping elements, can according to usual Procedure done. Such injection molding and extrusion articles may also from compounds containing the TPU according to the invention and at least one another thermoplastic, especially a polyethylene, Polypropylene, polyester, polyether, polystyrene, PVC, ABS, ASA, SAN, Polyacrylonitrile, EVA, PBT, PET, polyoxymethylene. Especially preferred become the TPU invention used for the production of articles by means of powder-slush Processes are produced, in particular instrument panels in Automobiles, for example foils for instrument panels.

Claims (9)

Process for the preparation of thermoplastic polyurethane particles, characterized in that molten thermoplastic polyurethane is dripped. Method according to claim 1, characterized in that that the molten thermoplastic polyurethane by means a dropper nozzle dripped into drops. Method according to claim 1, characterized in that that the molten thermoplastic polyurethane by means a vibrated perforated disc dripped. Method according to claim 1, characterized in that that the molten thermoplastic polyurethane in a spray tower dripped. Method according to claim 4, characterized in that that the spray tower a height between 2 m and 30 m. Method according to claim 1, characterized in that that drops of thermoplastic polyurethane have a diameter between 50 and 2000 μm exhibit. Method according to claim 1, characterized, then the thermoplastic polyurethane in a molten state from an extruder into a dropping device introduces. Thermoplastic polyurethane particles available through a method according to a of claims 1 to 7. Process for the production of articles based of thermoplastic polyurethanes by sintering of pulverized thermoplastic polyurethanes, characterized in that as powdered thermoplastic polyurethanes thermoplastic Polyurethane particles according to claim 8 inserts.