EXPANDED THERMOPLASTIC POLYURETHANE PARTICLES, METHOD FOR THE PRODUCTION THEREOF AND METHOD FOR THE PRODUCTION OF A MOULDED PART

Description

[0001] The invention relates to an expanded thermoplastic polyurethane composed of isocyanate, an isocyanate-reactive compound with a molecular weight between 500 and 10,000 g / mol, and chain extenders, which may additionally contain conventional additives. The invention further relates to a process for producing the expanded thermoplastic polyurethane and a process for producing a molded part from such an expanded thermoplastic polyurethane. The invention is set forth in the appended set of claims.

[0002] Expanded thermoplastic polyurethane can be used in a wide variety of applications due to its elastic and tribological properties. Expanded thermoplastic polyurethane granules are used, for example, for reusable exercise mats, body protectors, lining elements in automotive construction, sound and vibration dampers, packaging, and shoe soles. High elasticity and high compressive strength are crucial in all of these areas.

[0003] The production of such components is usually done from expanded particles that are poured into a mold and then bonded together. Steam is typically passed through the mold, causing the individual expanded particles to melt at the surface and bond together to form the molded part.

[0004] The chemical structure of thermoplastic polyurethanes and expanded thermoplastic polyurethanes is essentially the same. However, with expanded thermoplastic polyurethanes, a blowing agent is added during production, which foams the polyurethane during production. This also leads to different processes for subsequent processing to produce molded parts.

[0005] Non-expanded thermoplastic polyurethanes composed of an isocyanate, a compound reactive toward the isocyanate, and a chain extender are known, for example, from WO-A 2007 / 118827, US-A 2012 / 0083187, US-A 2010 / 0152405, DE-A 10 2006 021 734, or US-A 2009 / 0104449. In particular, WO-A 2007 / 118827 demonstrates that the hard phase content can be adjusted by a suitable choice of chain extender. For this purpose, two different chain extenders are used in a mixture in WO-A 2007 / 1188727.

[0006] Different expanded thermoplastic polyurethanes, which are also composed of an isocyanate, a compound reactive towards the isocyanate and a chain extender, are described in WO-A 2007 / 082838, WO-A 2013 / 153153, WO-A 2013 / 153190, WO-A 2015 / 052265 or WO-A 2015 / 055811.

[0007] Regardless of whether the thermoplastic polyurethane is produced as a solid polymer or as an expanded polymer, 1,4-butanediol is typically used as a chain extender. However, this has the disadvantage, particularly in expanded thermoplastic polyurethanes, that with a higher hard phase content, which leads to a higher storage modulus at room temperature (measured on a 2 mm thick injection-molded plate annealed for 20 hours at 100 °C in accordance with DIN EN ISO 6721-2:2011 in torsion mode, with a frequency of 1 Hz and a heating rate of 20 K / min from -80 °C to 200 °C) and thus a higher material strength, the melting temperature also increases. However, this is undesirable, especially for further processing into molded parts made from thermoplastic polyurethane particles, since the surface of the individual particles must be melted to bond them together to form molded parts.

[0008] The object of the present invention was therefore to provide expanded thermoplastic polyurethane particles which have a higher hard phase content and thus a higher storage modulus at room temperature (measured on a 2 mm injection-molded plate tempered for 20 h at 100 °C in accordance with DIN EN ISO 6721-2:2011, with a frequency of 1 Hz and a heating rate of 20 K / min from -80 °C to 200 °C), without the melting temperature of the thermoplastic polyurethane increasing significantly compared to the known thermoplastic polyurethanes in order to enable further processing.

[0009] This task is solved by expanded thermoplastic polyurethane particles, composed of isocyanate, polyol as a compound reactive towards the isocyanate with a number-average molecular weight between 500 and 10,000 g / mol and chain extender, whereby additional conventional additives can be included, the thermoplastic polyurethane has a hard phase content in the range of 0.1 to 0.95 and the hard phase content is Hartphasenanteil = ∑ x = 1 k m KVx M KVx ⋅ M Iso + m KVx m ges with M KVx : molar mass of the chain extender x in g / mol, m KVx : mass of the chain extender x in g M Ixo : molar mass of the isocyanate used in g / mol m ges : total mass of all starting materials without additives k: number of chain extenders and the chain extender is a diol having 5 to 10 carbon atoms, a mixture of at least two different diols, wherein at least one diol has 4 to 10 carbon atoms and all other diols have 2 to 10 carbon atoms, a mixture of at least a diol having 4 to 10 carbon atoms and at least one diamine or a mixture of at least one diol having 4 to 10 carbon atoms and an amino alcohol.

[0010] Surprisingly, it has been shown that when using a diol with 5 to 10 carbon atoms as a chain extender or a mixture of at least two diols, where at least one diol has 4 to 10 carbon atoms and all other diols have two to 10 carbon atoms, a mixture of at least one diol with 4 to 10 carbon atoms and at least one diamine or a mixture of at least one diol with 4 to 10 carbon atoms and an amino alcohol, the properties up to a temperature of 40°C show no significant changes compared to the use of 1,4-butanediol, however, the melting point and thus the processing temperature of the expanded thermoplastic polyurethane is reduced and thus also further processing of expanded particles made of a thermoplastic polyurethane with a higher hard phase content and thus a higher storage modulus at room temperature (measured on a 2 mm,for 20 h at 100 °C annealed injection-molded plate in accordance with DIN EN ISO 6721-2:2011 in torsion mode, with a frequency of 1 Hz and a heating rate of 20 K / min from -80 °C to 200 °C).

[0011] For the purposes of the present invention, "diol" refers to branched or unbranched aliphatic, araliphatic, cycloaliphatic, or aromatic hydrocarbons containing two hydroxyl groups. These compounds may additionally contain other functional groups and / or heteroatoms other than hydroxyl. However, diols without further functional groups and without heteroatoms are preferred.

[0012] The expanded thermoplastic polyurethane can be any thermoplastic polyurethane known to those skilled in the art. Thermoplastic polyurethanes and processes for their production have been described extensively, for example, in Gerhard W. Becker and Dietrich Braun, Kunststoffhandbuch, Volume 7, "Polyurethane," Carl Hanser Verlag, Munich, Vienna, 1993.

[0013] The number average molecular weight for the polyol is given below.

[0014] According to the invention, the thermoplastic polyurethane is produced by reacting a mixture of isocyanates with isocyanate-reactive compounds with a molecular weight between 500 and 10,000 g / mol, as well as chain extenders. In addition, conventional additives, such as chain regulators, catalysts, fillers, auxiliaries, or other additives, can be added.

[0015] For the production of the expanded thermoplastic polyurethane according to the invention, a mixture of isocyanate, isocyanate-reactive compound, and chain extender is required. The addition of other additives is optional and can be used individually or in any combination.

[0016] Organic isocyanates suitable for the production of thermoplastic polyurethane include, for example, aliphatic, cycloaliphatic, araliphatic, and / or aromatic isocyanates. Aromatic, aliphatic, and / or cycloaliphatic diisocyanates are particularly preferred.Examples of suitable diisocyanates are trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate; 2-methylpentamethylene-1,5-diisocyanate; 2-ethylbutylene-1,4-diisocyanate; butylene-1,4-diisocyanate; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; 1,4-bis(isocyanatomethyl)cyclohexane; 1,4-cyclohexane diisocyanate; 1-methyl-2,4-cyclohexane diisocyanate; 1-methyl-2,6-cyclohexane diisocyanate; 2,2'-dicyclohexylmethane diisocyanate; 2,4'-dicyclohexylmethane diisocyanate; 4,4'-dicyclohexylmethane diisocyanate; 2,2'-diphenylmethane diisocyanate; 2,4'-diphenylmethane diisocyanate; 4,4'-Diphenylmethane diisocyanate; 1,5-Naphthylene diisocyanate; 2,4-Tolylene diisocyanate; 2,6-Tolylene diisocyanate; Diphenylmethane diisocyanate; 3,3'-Dimethyldiphenyl diisocyanate; 1,2-Diphenylethane diisocyanate and phenylene diisocyanate, and any mixtures thereof.

[0017] The isocyanate-reactive compound used to produce the thermoplastic polyurethane is preferably selected from polyetherols, polyesterols, polybutadienols, and polycarbonatols, and mixtures thereof, as well as block copolymers thereof. Polyetherols, polyesterols, polybutadienols, and polycarbonatols are commonly referred to collectively as "polyols."

[0018] A polyetherol is preferably used to produce the thermoplastic polyurethane. Particularly preferred compounds that are reactive with the isocyanate are polytetrahydrofurandiol, polytrimethylene oxidediol, and polypropylene oxidediol. In addition to polyetherols, polyesterols or polycarbonatols are also preferred for producing the thermoplastic polyurethane. Polycaprolactonediols are particularly preferred as polyesterols.

[0019] In addition to polyols based on fossil raw materials, polyols produced from raw materials derived from renewable resources can also be used.

[0020] The polyols used to produce the thermoplastic polyurethane preferably have a molecular weight in the range from 500 to 8000 g / mol, more preferably from 600 to 6000 g / mol, and in particular from 800 to 4000 g / mol. Furthermore, it is preferred if the polyols have an average functionality of 1.3 to 2.3, further preferably from 1.9 to 2.2, and in particular 2. Therefore, polyetherdiols, polyesterdiols, polybutadienediols, and polycarbonatediols are preferred. If the polyol is a polyether alcohol, in particular polytetrahydrofurandiol, polytrimethylene oxidediol, or polypropylene oxidediol, the molecular weight is preferably between 600 and 2500 g / mol.

[0021] According to the invention, chain extenders are used to produce the expanded thermoplastic polyurethane, the amount of chain extender being selected such that the thermoplastic polyurethane produced has a hard phase content in the range from 0.1 to 0.95 and Hartphasenanteil = ∑ x = 1 k m KVx M KVx ⋅ M Iso + m KVx m ges with M KVx : molar mass of the chain extender x in g / mol, m KVx : mass of the chain extender x in g M Ixo : molar mass of the isocyanate used in g / mol m ges : total mass of all starting materials without additives k: number of chain extenders The chain extenders used are preferably aliphatic, araliphatic, aromatic, and / or cycloaliphatic compounds, preferably having a molecular weight of 50 to 500 g / mol. The chain extenders can be used individually or in mixtures. If only one chain extender is used, this is according to the invention a diol having 5 to 10 carbon atoms and preferably selected from the group consisting of 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclohexyldimethanol, 2-butyl-2-ethylpropanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, pinacol, 2-ethyl-1,3-hexanediol, 1,4-cyclohexanediol, N-phenyldiethanolamine.

[0022] If a mixture of at least two different chain extenders is used, at least one of the chain extenders used is a diol having 4 to 10 carbon atoms. All other chain extenders used can be selected from diols having 2 to 10 carbon atoms, diamines, or amino alcohols. If the chain extender is a mixture of at least two diols, the proportion of the diol having 4 to 10 carbon atoms, based on the total mass of the chain extender, is preferably in the range of 50 to 99.9 wt.%.

[0023] Preferred is the first diol, i.e. the diol having 4 to 10 carbon atoms, selected from 1,4-butanediol and 1,6-hexanediol.

[0024] In a mixture of at least two different diols, all other diols are preferably selected from 1,2-ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclohexyldimethanol, 2-butyl-2-ethylpropanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, pinacol, 2-ethyl-1,3-hexanediol, 1,4-cyclohexanediol, N-phenyldiethanolamine.

[0025] If the mixture of at least two chain extenders contains a diamine, this is preferably a diamine with a maximum of 17 C atoms, particularly preferably selected from ethylenediamine, isophoronediamine, methylenediphenyldiamine, 1,4-diaminobutane, trans-1,4-diaminocyclohexane, bis(4-amino-2-chloro-3,5-diethylphenyl)methane, 4,4'-methylenebis(2,6-diethylaniline), 4,4'-methylenebis(2-isopropyl-6-methylaniline), 4,4'-methylenebis(2,6-diisopropylaniline and 1,6-diaminohexane

[0026] When mixed with an amino alcohol, this is preferably selected from ethanolamine, 4-aminobutan-1-ol and 6-aminohexan-1-ol.

[0027] However, the chain extender is particularly preferably a diol or a mixture of at least two different diols. The chain extender is most preferably 1,6-hexanediol.

[0028] In addition to the chain extenders mentioned above, chain extenders with diol-functional groups can also be used in a mixture of several chain extenders. It is also possible to use chain extenders with carboxy-functional groups, which form amides upon reaction with an isocyanate group, releasing CO2. However, such chain extenders with carboxy-functional groups can only be added in small amounts, i.e., amounts of less than 40 wt.% based on the total mass of chain extender.

[0029] Surprisingly, it has been shown that by using the appropriate chain extenders, a wide variation of the hard phase content in the expanded thermoplastic polyurethane is possible, while at the same time achieving a processing temperature and melting temperature below 160°C, in particular below 120°C, so that in particular the processing to form a molded part from a particulate foam, i.e. welding of individual expanded particles, is possible.

[0030] The proportion of chain extenders is preferably adjusted such that the hard phase proportion is in the range from 0.15 to 0.5 and in particular in the range from 0.2 to 0.45. Due to an appropriate hard phase proportion, the resulting thermoplastic polyurethane has a sufficiently high storage modulus at room temperature (measured on a 2 mm thick injection-molded plate tempered for 20 h at 100 °C in accordance with DIN EN ISO 6721-2:2011 in torsion mode, with a frequency of 1 Hz and a heating rate of 20 K / min from -80 °C to 200 °C), preferably in the range from 5 to 100 MPa, and thus has sufficient strength, although this depends on the intended use of the expanded thermoplastic polyurethane.

[0031] The density of the expanded thermoplastic polyurethane particles (determined according to DIN EN ISO 527:2012) is in the range of 10 to 500 g / l, preferably in the range of 50 to 350 g / l.

[0032] In addition to the isocyanate, the isocyanate-reactive compound, and the chain extender, the polymer may also contain additives commonly used in the production of thermoplastic polyurethanes. Typical additives include chain regulators, catalysts, fillers, auxiliaries, and other additives. The addition of these additives to the thermoplastic polyurethane is optional and can be used individually or in a variety of ways.

[0033] If chain regulators are used, they typically have a molecular weight of 30 to 500 g / mol. Chain regulators are compounds that have only one functional group compared to isocyanates. Examples of chain regulators are monofunctional alcohols, monofunctional amines, preferably methylamine, and / or monofunctional polyols. Chain regulators can be used to specifically adjust the flow behavior of mixtures of the individual components. In preferred embodiments, chain regulators are used in an amount of 0 parts by weight to 5 parts by weight, more preferably 0.1 part by weight to 1 part by weight, based on 100 parts by weight of the compound having at least two hydrogen-containing groups reactive with isocyanate groups. The chain regulators are used in addition to the chain extenders.

[0034] To accelerate the reaction between the isocyanate groups of the diisocyanates and the isocyanate-reactive compounds, in particular hydroxyl groups, of the chain regulators and chain extenders, it is possible to use a catalyst. The catalyst is preferably selected from the group of tertiary amines, for example triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N,N-dimethylpiperazine, 2-(dimethylaminoethoxy)ethanol, diazabicyclo-(2,2,2)octane and similar substances. More preferably, the at least one catalyst is selected from the group of organic metal compounds and is exemplified by titanic acid esters, an iron compound, for example iron(III) acetylacetonate, a tin compound, for example tin diacetate, tin dioctoate, tin dilaurate or a tin dialkyl salt of an aliphatic carboxylic acid such as dibutyltin diacetate, dibutyltin dilaurate or the like.

[0035] The catalysts can be used individually or in mixtures of catalysts. A mixture of catalysts is preferably used as the catalyst in amounts of 0.001 wt.% to 0.1 wt.%, based on the compound having at least two hydrogen-containing groups reactive with isocyanate groups, preferably the polyhydroxyl compound.

[0036] Auxiliaries and / or other additives that can be used include hydrolysis inhibitors and / or antioxidants. Further additives and auxiliaries can be found in standard works such as the aforementioned Gerhard W. Becker and Dietrich Braun, Kunststoffhandbuch, Volume 7 "Polyurethane," Carl Hanser Verlag, Munich, Vienna, 1993.

[0037] In addition to catalysts, but also without the use of catalysts, hydrolysis protection agents, for example polymers and low molecular weight carbodiimides, can also be added to the isocyanates and the compound with at least two hydrogen-containing groups reactive with isocyanate groups to produce the thermoplastic polyurethane.

[0038] The thermoplastic polyurethane may also contain a phosphorus compound. Organophosphorus compounds of trivalent phosphorus, such as phosphites and phosphonites, are preferably used as phosphorus compounds. Examples of suitable phosphorus compounds are triphenyl phosphites, diphenyl alkyl phosphite, phenyl dialkyl phosphite, tris-(nonylphenyl) phosphite, trilauryl phosphite, trioctadecyl phosphite, distearyl pentaerythritol diphosphite, tris-(2,4-di-tert-butylphenyl) phosphite, diisopentaerythritol diphosphite, di-(2,4-di-tert-butylphenyl)-pentaerythritol diphosphite, tristearyl sorbitol triphosphite, tetrakis-(2,4-di-tert-butylphenyl)-4,4'-diphenylenediphosphonite, triisodecyl phosphite, diisodecyl phenyl phosphite and diphenyl isodecyl phosphite or mixtures thereof.

[0039] Particularly preferred are phosphorus compounds that are difficult to hydrolyze, since the hydrolysis of a phosphorus compound to the corresponding acid can lead to damage to the polyurethane, especially the polyester urethane. Accordingly, phosphorus compounds that are particularly difficult to hydrolyze are particularly suitable for polyester urethanes. Preferred phosphorus compounds that are difficult to hydrolyze include, for example, dipolypropylene glycol phenyl phosphite, phenyl diisodecyl phosphite, diphenyl monodecyl phosphite, triisononyl phosphite, tris-(2,4-di-tert-butylphenyl) phosphite, tetrakis-(2,4-di-tert-butylphenyl)-4,4'-diphenylene disphosphonite, and di-(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, or mixtures thereof.

[0040] To adjust the hard phase content and thus both the storage modulus at room temperature (measured on a 2 mm thick injection-molded plate tempered for 20 h at 100 °C in accordance with DIN EN ISO 6721-2:2011 in torsion mode, with a frequency of 1 Hz and a heating rate of 20 K / min from -80 °C to 200 °C) and the Shore hardness of the thermoplastic polyurethane, the compounds with at least two hydrogen-containing groups reactive with isocyanate groups and the chain extenders can be varied in relatively wide molar ratios. In preferred embodiments, the molar ratio of the compounds having at least two hydrogen-containing groups reactive with isocyanate groups to the total chain extender used is 10:1 to 1:10, preferably 5:1 to 1:8, more preferably 1:1 to 1:4, the hardness of the thermoplastic polyurethane increasing with increasing content of chain extender.In this way, Shore hardnesses from A75 to D60, particularly preferably from A83 to A95, and especially from A85 to A90, can be achieved. The Shore hardnesses are determined according to DIN ISO 7619-1:2012 on compact, i.e., non-expanded, thermoplastic polyurethane. For this purpose, sheets are used that are manufactured either from the starting material or from remelted expanded thermoplastic polyurethane particles or molded parts made from them.

[0041] The storage modulus can also be adjusted by adjusting the ratio of the isocyanate-reactive compound to the chain extender. This is preferably also determined on the compact, unexpanded thermoplastic polyurethane. The storage modulus of the polyurethane without fillers at room temperature (measured on a 2 mm thick injection-molded plate annealed for 20 hours at 100 °C in accordance with DIN EN ISO 6721-2:2011 in torsion mode, with a frequency of 1 Hz and a heating rate of 20 K / min from -80 °C to 200 °C) is preferably in the range of 1 to 300 MPa, more preferably in the range of 5 to 200 MPa, and especially in the range of 10 to 100 MPa.

[0042] By using the diol with 5 to 10 carbon atoms or the mixture of at least two diols, where at least one diol has 4 to 10 carbon atoms and all other diols have 2 to 10 carbon atoms, the mixture of at least one diol with 4 to 10 carbon atoms and at least one diamine or the mixture of at least one diol with 4 to 10 carbon atoms and an amino alcohol as chain extender, even with high hard phase contents, i.e. with high Shore hardness and high storage moduli at room temperature (measured on a 2 mm thick injection-molded plate tempered for 20 h at 100 °C in accordance with DIN EN ISO 6721-2:2011 in torsion mode, with a frequency of 1 Hz and a heating rate of 20 K / min from -80 °C to 200 °C), a processing temperature is achieved that is significantly lower than when using the commonly used 1,2-ethylene glycol or 1,4-butanediol as chain extenders.In particular, the expanded polyurethane made from thermoplastic polyurethane can still be processed at temperatures below 160°C.

[0043] The conversion to thermoplastic polyurethane preferably takes place at conventional ratios, where the ratio is defined by the ratio of the total isocyanate groups used in the reaction, of the aromatic, aliphatic and / or cycloaliphatic diisocyanate to the isocyanate-reactive groups, i.e. the active hydrogens of the compound with at least two isocyanate-reactive hydrogen groups and chain extenders. With a ratio of 100, there is one active hydrogen atom for each isocyanate group of the aromatic, aliphatic and / or cycloaliphatic diisocyanate, i.e. one isocyanate-reactive function of the compound with at least two isocyanate-reactive hydrogen groups and the chain extender. With ratios above 100, there are more isocyanate groups than isocyanate-reactive groups, for example hydroxyl groups.

[0044] In particularly preferred embodiments, the conversion to the thermoplastic polyurethane takes place at a value between 60 and 120, more preferably at a value between 80 and 110.

[0045] Auxiliaries and other additives used in addition to catalysts and chain regulators include, for example, surfactants, flame retardants, oxidation stabilizers, slip and demolding aids, dyes and pigments, and possibly additional stabilizers, for example, to protect against hydrolysis, light, heat, or discoloration, reinforcing agents, and plasticizers. If fillers are used, these can be inorganic and / or organic.

[0046] If the thermoplastic polyurethane contains fillers, these can be organic or inorganic powders or fibers, as well as mixtures thereof. Examples of organic fillers that can be used include wood flour, starch, flax, hemp, ramie, jute, sisal, cotton, cellulose, or aramid fibers. Suitable inorganic fillers include silicate, barite, glass beads, zeolites, metals, or metal oxides. Particular preference is given to powdered inorganic materials such as chalk, kaolin, aluminum hydroxide, magnesium hydroxide, aluminum nitrite, aluminum silicate, barium sulfate, calcium carbonate, calcium sulfate, silicic acid, quartz powder, aerosil, alumina, mica, or wollastonite, or spherical or fibrous inorganic materials such as iron powder, glass beads, glass fibers, or carbon fibers.The average particle diameter, or in the case of fibrous fillers, the length of the fibers, should be in the range of the cell size or smaller. A mean particle diameter or an average fiber length in the range of 0.01 to 100 µm is preferred, more preferably in the range of 0.1 to 50 µm. Expandable, blowing-agent-containing thermoplastic polyurethanes containing between 5 and 80 wt.% organic and / or inorganic fillers, based on the total weight of the blowing-agent-containing thermoplastic polyurethane, are preferred.

[0047] To reduce the radiation contribution to thermal conductivity, the thermoplastic polyurethane can contain IR opacifiers such as metal oxides, non-metal oxides, metal powders, for example, aluminum powder, carbon, for example, carbon black, graphite, graphene, graphene oxides, carbon nanotubes, diamond, or organic dyes and dye pigments, which is particularly advantageous for high-temperature applications. Carbon black, titanium dioxide, iron oxides, or zirconium dioxide are particularly preferred. These materials can be used individually or in combination, i.e., in the form of a mixture of several materials.

[0048] Surface-active substances that may be contained in thermoplastic polyurethane include compounds that support the homogenization of the starting materials and may also be suitable for regulating cell structure. Suitable surface-active substances include emulsifiers, for example, sodium salts of castor oil sulfates or fatty acids, as well as salts of fatty acids with amines, for example, oleic acid diethylamine, stearic acid diethanolamine, ricinoleic acid diethanolamine; salts of sulfonic acids, for example, alkali or ammonium salts of dodecylbenzenesulfonic acid or dinaphthylmethanedisulfonic acid and ricinoleic acid; foam stabilizers such as siloxane-oxyalkylene copolymers and other organosiloxanes, ethoxylated alkylphenols, ethoxylated fatty alcohols, paraffin oils, castor oil or ricinoleic acid esters, turquoise meal oil and peanut oil; and cell regulators, for example, paraffins, fatty alcohols, and dimethylpolysiloxane.Oligomeric polyacrylates with polyoxyalkylene and fluoroalkane residues as side groups are also suitable for improving the emulsifying effect of the cell structure or for stabilizing it. The surfactants are typically used in amounts of 0.01 to 5 wt.%, based on the total weight of the thermoplastic polyurethane.

[0049] Suitable flame retardants that can be contained in the thermoplastic polyurethane are, for example, tricresyl phosphate, tris-(2-chloroethyl) phosphate, tris-(2-chloropropyl) phosphate, tris-(1,3-dichloropropyl) phosphate, tris-(2,3-dibromopropyl) phosphate, and tetrakis-(2-chloroethyl)ethylene diphosphate. In addition to the halogen-substituted phosphates already mentioned, inorganic flame retardants containing red phosphorus, aluminum oxide hydrate, antimony trioxide, arsenic trioxide, ammonium polyphosphate and calcium sulfate or cyanuric acid derivatives, for example melamine, or mixtures of at least two flame retardants, for example ammonium phosphate and melamine, and optionally starch and / or expandable graphite, can also be used to flame-retard the foamed polyurethanes produced. In general, it has proven advantageous to use 0 to 50% by weight, preferably 5 to 25% by weight.-% of the flame retardant or flame retardant mixture based on the total weight of the thermoplastic polyurethane.

[0050] To produce the expanded thermoplastic polyurethane, it is further preferred to add one or more nucleating agents. Particularly suitable nucleating agents are talc, calcium fluoride, sodium phenylphosphinate, aluminum oxide, carbons such as carbon black, carbon nanotubes, graphite, graphene and graphene oxides, pigments, and finely divided polytetrafluoroethylene, either individually or in any desired mixtures.

[0051] Talc is particularly preferred as a nucleating agent. The proportion of nucleating agent based on the total mass of the thermoplastic polyurethane or the melt of the thermoplastic polyurethane is preferably 0 to 4 wt.%, in particular 0.1 to 2 wt.%.

[0052] Known processes can be used to produce the expanded thermoplastic polyurethane. It is particularly preferred if the amount of blowing agent used to produce the expanded thermoplastic polyurethane is selected such that the expanded thermoplastic polyurethane is more than 85% closed-cell and has an average cell size in the range of 0.1 to 800 µm, preferably in the range of 1 to 500 µm, in particular in the range of 5 to 250 µm, and very preferably in the range of 50 to 150 µm. The proportion of closed cells and the cell size can be determined, for example, optically using microscopic images.

[0053] All conventional blowing agents known to those skilled in the art can be used as blowing agents for producing the expanded thermoplastic polyurethane particles. The blowing agents used depend on the production process of the expanded thermoplastic polyurethane particles and are described in more detail below in connection with the production processes of the expanded thermoplastic polyurethane particles.

[0054] To produce the expanded thermoplastic polyurethane particles, a process is used that includes the following steps: (a) reacting an isocyanate with a polyol as a compound reactive towards the isocyanate and chain extender, optionally in the presence of at least one catalyst and / or additive, to form a polyurethane, wherein the amounts of isocyanate, compound reactive towards the isocyanate and chain extender are adjusted such that the thermoplastic polyurethane has a hard phase proportion in the range from 0.1 to 0.95 and the hard phase proportion is Hartphasenanteil = ∑ x = 1 k m KVx M KVx ⋅ M Iso + m KVx m ges with M KVx : molar mass of the chain extender x in g / mol, m KVx : mass of the chain extender x in g M Ixo : molar mass of the isocyanate used in g / mol m ges : total mass of all starting materials without additives k: number of chain extenders, and the chain extender is a diol having 5 to 10 carbon atoms, a mixture of at least two different diols, where at least one diol has 4 to 10 carbon atoms and all other diols have 2 to 10 carbon atoms, a mixture of at least one diol having 4 to 10 carbon atoms and at least one diamine or a mixture of at least one diol having 4 to 10 carbon atoms and an amino alcohol. (b) impregnating the polyurethane with a blowing agent; (c) relaxing the pressure of the polyurethane impregnated with the blowing agent to give the expanded thermoplastic polyurethane.

[0055] The reaction of the isocyanate with the isocyanate-reactive compound and the chain extender in step (a) can be carried out continuously by processes known to those skilled in the art, for example, using reaction extruders or the one-shot belt process or the prepolymer process, or discontinuously by the known prepolymer process. In these processes, the reacting components can be mixed together sequentially or simultaneously, with the reaction starting immediately.

[0056] During production in a reaction extruder, the isocyanate, the isocyanate-reactive compound, the chain extender, and optionally the catalyst and / or additives are introduced into the extruder individually or as a mixture and reacted, for example, at temperatures in the range of 100 to 280°C, preferably in the range of 140 to 250°C. The resulting thermoplastic polyurethane is extruded, cooled, and granulated. It may be advantageous to heat the resulting thermoplastic polyurethane at 80 to 120°C, preferably at 100 to 110°C, for a period of 1 to 24 hours before further processing.

[0057] The thermoplastic polyurethane produced is used according to the invention to produce the expanded polyurethane particles. The particles preferably have a maximum length in the range of 1 to 25 mm, in particular a maximum length of 2 to 15 mm.

[0058] After the thermoplastic polyurethane is produced, it is impregnated with a blowing agent and then expanded to form thermoplastic polyurethane particles.

[0059] In one embodiment, for example, it is possible for the polyurethane to be impregnated with the blowing agent in an extruder, the impregnated polyurethane to be cut into granules, and the granules to be expanded after cutting to form expanded thermoplastic polyurethane particles. To impregnate the polyurethane with the blowing agent, the thermoplastic polyurethane is melted in the extruder and mixed with a blowing agent that is fed to the extruder. The blowing agent-containing mixture is then extruded and granulated under pressure and temperature conditions such that the thermoplastic polyurethane granules do not foam (expand), for which purpose, for example, underwater granulation is used, which is operated at a water pressure of more than 2 bar and a water temperature of 10°C to 40°C.In this case, expandable particles containing a blowing agent are obtained, which are foamed into the expanded particles by subsequent heating. Alternatively and preferably, however, it is also possible to adjust the pressure and temperature conditions in the underwater pelletizing process to promote expansion. In this case, the melt strand leaving the extruder foams, and the expanded particles are obtained by pelletizing. The pressure and temperature depend on the polyurethane used and the amount of blowing agent. The pressure is usually in the range of 1 to 20 bar, preferably in the range of 2 to 15 bar, and the temperature between 20°C and 60°C, preferably between 20°C and 40°C. The pressure and temperature to be set depend on the polyurethane to be processed.

[0060] The production of the thermoplastic polyurethane and the addition of the blowing agent to produce the expanded thermoplastic polyurethane can take place in two different extruders. Alternatively, it is also possible to use a single extruder. In this case, the front part of the extruder, into which the isocyanate, the isocyanate-reactive compound, the chain extender, and any other additives are added, serves as the reactive extruder. The blowing agent is added at a later point in the extruder, where the conversion to polyurethane is complete.

[0061] In an alternative embodiment, the polyurethane produced in step (a) is cut into granules. These granules are impregnated in an aqueous suspension with 0.1 to 40 wt. % of a blowing agent at a temperature in the range of 100 to 160°C and a pressure in the range of 5 to 100 bar. The suspension is then cooled to 20 to 95°C, and the resulting blowing agent-containing granules are subsequently decompressed. In this case, it is possible to first cool the aqueous suspension containing the granules, whereby the particles solidify with the blowing agent enclosed, and then to decompress the reactor. The resulting blowing agent-containing particles are then foamed into expanded particles by heating.Alternatively, it is also possible to abruptly expand the hot aqueous suspension containing the granules without cooling (explosive expansion process), whereby the softened, blowing agent-containing particles foam immediately to form the expanded particles. The production of the expanded thermoplastic polyurethane can, in principle, be carried out as described in WO-A 2007 / 082838.

[0062] The blowing agent used to produce the expanded thermoplastic polyurethane particles can vary depending on the manufacturing process. When added to an extruder or impregnation vessel, the blowing agent used is preferably a volatile organic compound with a boiling point at atmospheric pressure of 1013 mbar in the range of -25 to 160°C, in particular -10 to 125°C. Optionally halogen-substituted hydrocarbons are particularly suitable, with halogen-free hydrocarbons being preferred. Particular preference is given to C 4 -C 10 alkanes, for example the isomers of butane, pentane, cyclopentane, hexane, heptane, and octane, with s-pentane being particularly preferred. Other suitable blowing agents include sterically demanding compounds such as alcohols, ketones, esters, ethers, and organic carbonates. The organic blowing agents can also be combined.Suitable inorganic gases include nitrogen, air, ammonia, or carbon dioxide, or combinations of these or combinations with the other blowing agents mentioned above. These inorganic gases can also be used for impregnation in an autoclave.

[0063] Halogenated hydrocarbons can also be used, but the blowing agent is preferably halogen-free. However, small amounts of halogen-containing blowing agents in the blowing agent mixture should not be ruled out. The blowing agents can be used either as pure substances or in any desired mixture.

[0064] In addition to the blowing agents mentioned, it is possible to use nitrogen and / or carbon dioxide, in particular supercritical carbon dioxide, in the production of the expanded thermoplastic granules both by extrusion and in aqueous suspension.

[0065] The amount of blowing agent is preferably in the range of 0.1 to 40 parts by weight, in particular 0.5 to 35 and particularly preferably 1 to 30 parts by weight, based on 100 parts by weight of thermoplastic polyurethane used.

[0066] The expanded thermoplastic polyurethane particles are used in particular for the production of molded parts from particle foams. To produce a molded part from such expanded thermoplastic polyurethane particles, a suitable process comprises the following steps: (a) introducing the expanded thermoplastic polyurethane particles into a mold; (b) exposing the expanded thermoplastic polyurethane particles introduced into the mold to steam, hot air, or high-energy radiation so that the expanded thermoplastic polyurethane particles melt at the surface and weld together to form the molded part.

[0067] The heating of the surface of the expanded thermoplastic polyurethane particles required for welding, so that they begin to melt, is achieved by exposure to steam, hot air, or high-energy radiation, individually or in any combination. Suitable high-energy radiation includes microwave radiation, radio radiation, or infrared radiation. However, the use of steam or hot air, especially steam, is preferred.

[0068] If steam is used to weld the expanded thermoplastic polyurethane particles, the temperature of the steam introduced into the mold can be adjusted by pressure. The higher the pressure, the higher the boiling point of the water and thus the temperature the steam can reach. In addition to saturated steam, the use of superheated steam or unsaturated steam is also possible. Suitable pressures for introducing the steam into the mold are between 0.1 bar and 6 bar, preferably between 0.3 and 3 bar.

[0069] By using the expanded thermoplastic polyurethane according to the invention, it is possible to produce molded parts with a high hard phase fraction, in particular a hard phase fraction greater than 0.35, and thus molded parts with a comparatively high storage modulus at room temperature (measured on a 2 mm thick injection-molded plate tempered for 20 h at 100 °C in accordance with DIN EN ISO 6721-2:2011 in torsion mode, with a frequency of 1 Hz and a heating rate of 20 K / min from -80 °C to 200 °C) and correspondingly high hardness, since despite the high hard phase fraction, a processing temperature, in particular the beginning of the melting range of the hard phase of the expanded thermoplastic polyurethane, is obtained which is below 160 °C, preferably in the range from 100 to 140 °C.The onset of melting of the hard phase correlates with the sudden drop in the storage modulus at the end of the viscoelastic plateau at a temperature above 80 °C. The pressure and temperature of the steam used to produce the molded part are selected so that, when exposed to steam, the expanded thermoplastic polyurethane granules only melt at the surface, thus bonding neighboring particles together. During the production of the molded part, it is important to avoid completely melting the thermoplastic polyurethane, as this would result in a solid block.To prevent the expanded thermoplastic granules from completely melting, the duration for which the expanded thermoplastic polyurethane particles are exposed to steam, hot air, or high-energy radiation is adjusted so that only a partial melting of the surface occurs. This means that as the temperature of the steam or hot air increases, or the intensity of the high-energy radiation increases, the duration of exposure is shortened. To ensure partial melting, when using steam or hot air, it is necessary that the temperature of the steam or hot air is above the melting temperature of the expanded thermoplastic polyurethane. Welding is preferably carried out in such a way that the particulate surface structure of the final molded part is retained as far as possible.

[0070] Examples of molded parts that can be manufactured in this way include shoe soles, gymnastics mats, body protectors, lining elements in automotive engineering, silencers, vibration dampers, for example for suspension forks, upholstery, bicycle saddles, toys, tires or tire parts, surfaces for athletics tracks, sports halls or sidewalks, or packaging. Examples Preparation of example and reference materials

[0071] At a distance of 6 L / D from the start of the process section of a Coperion GmbH ZSK43 twin-screw extruder acting as a reaction extruder, 4,4'-diphenylmethane diisocyanate, polytetramethylene glycol with a number-average molecular weight (M n ) of 1000 ± 100 g / mol, a diol, and 1 wt. % UV and thermal stabilizers were metered in for the mixing and synthesis of various thermoplastic polyurethanes. The mixture was mixed with 30 ppm of tin(II) dioctoate as a catalyst at a temperature between 180 and 220°C, and reacted. The distance of 6 L / D was chosen to prevent refluxing monomer from entering the gear unit. The exact proportions of the individual components of the respective example and reference materials are listed in Table 1.

[0072] From the reaction extruder, the reaction mixture is transferred to a ZSK92 twin-screw extruder from Coperion GmbH, which serves as the main extruder. The inlet of the main extruder is located 6 L / D from the start of the process section. The reaction continues in the main extruder at temperatures ranging from 200 to 240°C.

[0073] A melt pump forces the polymer melt through a perforated plate heated to 200°C into a pelletizing chamber through which water flows. The holes in the perforated plate have a diameter of 1.8 mm. Rotating knives in the pelletizing chamber cut the polymer melt into pellets at the perforated plate. The pellets are discharged from the pelletizing chamber with the water and conveyed to a centrifugal dryer. In the centrifugal dryer, the pellets are separated from the water and then dried at 70°C for 4 hours. Table 1: Quantities of the components of the thermoplastic materials dosed into the reaction extruder as example and reference materials Designation Polytetramethylene glycol 4,4'-Diphenylmethane diisocyanate Diol Example: Mat. 1 57% by weight 33.1 wt.% 8.9 wt.% 1,6-hexanediol Example Mat. 2 53.8% by weight 35% by weight 10.2 wt.% 1,6-hexanediol Example Mat. 3 49.1% by weight 37.8 wt.% 12.1 wt.% 1,6-hexanediol Ref. Mat. 1 59.2 wt.% 33.2 wt.% 6.6 wt.% 1,4-butanediol Ref. Mat. 2 56.3 wt.% 35.2 wt.% 7.5 wt.% 1,4-butanediol Ref. Mat. 3 53% by weight 37.4% by weight 8.6 wt.% 1,4-butanediol Ref. Mat. 4 59.2 wt.% 33.9 wt.% 5.8 wt.% 1,3-propanediol

[0074] This production process yields thermoplastic polyurethanes with the properties listed in Table 2. The Shore hardness of injection-molded sheets, which had been annealed for 20 h at 100 °C, was determined at room temperature according to DIN ISO 7619-1:2012 after an indentation time of 3 s. The melt flow rate (MFR) of the granules was measured according to DIN EN ISO 1133-2:2012. The beginning of the melting range of the hard phase was determined from dynamic mechanical analysis (DMA) measurements (heating rate 20 K / min, frequency 1 Hz) according to DIN EN ISO 6721-2:2011 in torsion mode. Table 2: Properties of the prepared example and reference materials Designation Shore hardness MFR (190 °C, 21.6 kg) Beginning of the melting range of the hard phase Example: Mat. 1 83 ± 2 A >40g / 10 min 110 °C Example Mat. 2 85 ± 2 A >40g / 10 min 110 °C Example Mat. 3 90 ± 2 A >40g / 10 min 110 °C Ref. Mat. 1 83 ± 2 A >40g / 10 min 115 °C Ref. Mat. 2 85 ± 2 A >40g / 10 min > 120 °C Ref. Mat. 3 90 ± 2 A >40g / 10 min > 120 °C Ref. Mat. 4 83 ± 2 A >40g / 10 min > 120 °C Production of the expanded granules by impregnation in an extruder

[0075] After the feedstocks had been produced, they were further processed into expanded thermoplastic polyurethane granules as follows. For this purpose, the dried example and reference materials were mixed in a twin-screw extruder (ZE 75, KraussMaffei Bernstorff) with further additives such as 0.1 wt.% talc as a nucleating agent and, if required, a TPU, which had been mixed with 4,4'-diphenylmethane diisocyanate with an average functionality of 2.05 in a separate extrusion process, and melted in a temperature range of 160 °C to 220 °C. CO2 and N2 were injected into the melt in the extruder as blowing agents and mixed with the thermoplastic polyurethane and the other additives to form a homogeneous melt. The exact composition of the individual examples and comparative examples is listed in Table 3. The melt mixture was then pumped into a perforated plate (approx. 160-200 °C depending on the material composition) using a gear pump.180 - 200°C depending on the material composition) and cut into granules in the cutting chamber of the underwater granulation (UWG). These granules are then transported away with tempered and pressurized water, where they expand. After the expanded granules are separated from the water using a centrifugal dryer, the expanded granules are dried at 60°C for 2 hours. The water temperature and water pressure used for the individual examples and comparative examples, as well as the resulting bulk densities of the expanded granules, are listed in Table 3. In Examples 1 to 3, Example Material 2 was used, and in Example 4, Example Material 3. In Comparative Examples 1, 2, 5, and 6, Reference Material 1 was used; in Comparative Example 3, Reference Material 2; in Comparative Example 4, Reference Material 3; and in Comparative Example 7, Reference Material 4.In addition, in Examples 3 and 4 as well as Comparative Examples 2, 3 and 4, 1 wt.% of the TPU, which was mixed with 4,4'-diphenylmethane diisocyanate with an average functionality of 2.05 in a separate extrusion process, was added. Table 3: Data on the examples and comparative examples Proportion of example or reference material (wt.%) Particle mass (mg) Bulk density (kg / m 3< ) CO 2 (wt.%) N 2 (wt.%) Water pressure in the UWG (bar) Water temperature in the UWG (°C) Example 1 99,9 25 132 1,0 0,22 2,5 23 Example 2 99,9 32 131 1,0 0,21 3,0 23 Example 3 98,9 32 121 1,2 0,21 4,5 30 Example 4 98,9 32 122 1,2 0,22 3 30 See Example 1 99,9 25 139 1,2 0,22 3,6 30 See Example 2 98,9 25 129 1,0 0,23 2,6 20 See Example 3 98,9 25 147 1,2 0,16 3,1 38 See Example 4 98,9 25 138 0,7 0,25 1,8 35 See Example 5 99,9 32 123 1,1 0,21 3,3 30 See Example 6 98,9 32 133 1,2 0,21 3 30 See Example 7 99,9 25 160 1,0 0,21 2,6 27

[0076] The expanded granules were then welded to square sheets with a side length of 200 mm and a thickness of 10 mm or 20 mm by exposure to steam on a Kurtz ersa GmbH molding machine (Boost Foamer). The same steaming conditions were used regardless of the sheet thickness. The welding parameters for the different materials were selected so that the sheet side of the final molded part, which faced the movable side of the mold, had the lowest possible number of collapsed ETPU particles. Where necessary, gap steaming was also carried out through the movable side of the mold. Achieving a satisfactory surface quality was not always possible in the comparative examples. Regardless of the test, a cooling time of 120 s was always set at the end for both the fixed and movable sides of the mold.The respective vapor deposition conditions are listed in Table 4 as vapor pressures and in Table 5 as corresponding vapor temperatures. This results in a lower maximum vapor pressure required to weld the polyurethane particles of the examples compared to those of the comparative examples.

[0077] The surfaces of the plates facing the moving side of the tool are shown in the figures.

[0078] They show: Fig. 1 is a surface photograph of the plate produced in Example 1, Fig. 2 is a surface photograph of the plate produced in Example 3, Fig. 3 is a surface photograph of the plate produced in Example 4, Fig. 4 is a surface photograph of the plate produced in Comparative Example 3, Fig. 5 is a surface photograph of the plate produced in Comparative Example 4, Fig. 6 is a surface photograph of the plate produced in Comparative Example 6.

[0079] It is clearly evident that, with comparable Shore hardnesses of the starting material listed in Table 2, satisfactory surfaces, in which the particle structure is still recognizable, are only obtained for the panels produced according to the examples and Comparative Example 6. The panels produced according to Comparative Examples 3 and 4 have a smooth surface, which indicates a plastic change in the surface structure of the panel. Table 4: Steam pressures and welding times for the materials of the examples and comparative examples Gap vapor deposition (bar) Gap vapor deposition (s) Transverse steam fixed side (bar) Transverse steam fixed side (s) Transverse steam movable side (bar) Transverse steam moving side (s) Autoclave steam fixed / movable side (bar) Autoclave steam (s) Example 1 0,75 10 1,2 20 - - - - Example 2 0,75 10 1,2 20 - - - - Example 3 - - 1,6 10 1,6 10 1,0 / 1,0 15 Example 4 - - 1,3 40 - - 1,3 / 0,8 10 See Example 1 1,3 18 1,8 30 - - - - See Example 2 0,4 5 2,2 40 2,2 40 - - See Example 3 0,7 30 2,2 7 2,6 7 1,9 / 1,9 32 See Example 4 - - 1,9 7 1,9 7 1,9 / 1,9 32 See Example 5 - - 1,1 15 1,3 30 - - See Example 6 - - 1,9 10 2 20 - - See Example 7 Welding at 3 bar not possible Table 5: Steam temperatures (measured at the tool) and times for welding the materials of the examples and comparative examples Gap vapor deposition (°C) Gap vapor deposition (s) Transverse steam fixed side (°C) Transverse steam fixed side (s) Transverse steam moving side (°C) Transverse steam moving side (s) Autoclave steam fixed / movable side (°C) Autoclave steam (s) Example 1 116 10 123 20 - - - - Example 2 116 10 123 20 - - - - Example 3 - - 128 10 128 10 120 / 120 15 Example 4 - - 124 40 - - 124 / 116 10 See Example 1 124 18 131 30 - - - - See Example 2 109 5 135 40 135 40 - - See Example 3 115 30 135 7 139 7 132 / 132 32 See Example 4 - - 132 7 132 7 132 / 132 32 See Example 5 - - 121 15 124 30 - - See Example 6 - - 132 10 133 20 - - See Example 7 Welding at 143 °C not possible

[0080] The weld quality of the sheets can be determined using the tear strength (DIN ISO 34-1, test specimen 100 x 50 mm with a 50 mm incision). The higher the tear strength, the better the weld for starting materials with identical Shore hardness. The values ​​for the examples and comparative examples are listed in Table 6. Table 6: Results of the tear strength of the welded plates of the examples and comparative examples (plate thickness 20 mm) Board density (kg / m 3< ) Tear resistance (N / mm) Example 1 236 4 ± 0,11 Example 2 232 3,58 ± 0,28 Example 3 208 3,9 ± 0,3 Example 4 226 2,58 ± 0,1 See Example 1 287 3,96 ± 0,17 See Example 2 292 3,45 ± 0,10 See Example 3 327 3,5 ± 0,2 See Example 4 299 0,59 ± 0,1 See Example 5 272 1,88 ± 0,59 See Example 6 263 1,57 ± 0,27

[0081] As an alternative to tear strength, the tensile strength of the samples can also be tested. This was determined for a sheet thickness of 10 mm based on ASTM D5035:2015, which was developed for textiles. The values ​​are listed in Table 7. Table 7: Tensile test results of the welded plates of the examples and comparative examples (plate thickness 10 mm) Board density (kg / m 3< ) Tensile strength (kPa) Elongation at break (%) Example 1 270 1460 ± 90 169 ± 17 Example 2 235 911 ± 38 119 ± 3 Example 3 240 820 ± 20 104 ± 10 Example 4 230 850 ± 6 71 ± 13 See Example 1 301 812 ± 73 95 ± 14 See Example 2 305 919 ± 83 120 ± 17 See Example 3 310 819 ± 20 83 ± 4 See Example 4 314 730 ± 70 53 ± 8 See Example 5 281 450 ± 9 53 ± 11 See Example 6 291 710 ± 6 89 ± 10 Production of the expanded granules by impregnation in an autoclave

[0082] For Examples 5 and 6 and Comparative Examples 8 and 9, Example Materials 2 and 3 and Reference Materials 2 and 3 were further processed as described below.

[0083] The tests were conducted with a vessel filling level of 80% and a phase ratio of 0.39. The phase ratio is defined as the ratio of the mass of granules to the suspension medium, which in the examples is water.

[0084] 100 parts by weight of the granules (corresponding to 28.0 wt.%, based on the total suspension without propellant), 257 parts by weight of water (corresponding to 72.0 wt.%, based on the total suspension without propellant), 0.13 part by weight of a surfactant (Lutensol AT 25) (corresponding to 0.04 wt.%, based on the total suspension without propellant), and the appropriate amount of butane as propellant (based on the amount of granules used) were heated while stirring. Nitrogen was then injected into the liquid phase at 50°C, and the internal pressure was adjusted to 800 kPa. Subsequently, upon reaching the impregnation temperature and, if necessary, after observing a holding time and at the final impregnation pressure, the pressure was released using a pressure release device.

[0085] The holding time is defined as the time during which the temperature of the liquid phase is in a temperature range of 5°C below the impregnation temperature and 2°C above the impregnation temperature.

[0086] After drying, the bulk density of the resulting foam particles is measured.

[0087] The exact manufacturing parameters and the bulk density of the resulting product are listed in Table 8. Table 8: Data on the examples and comparative examples Material used Propellant content [%] Impregnation temperature [°C] Holding time [min] Impregnation pressure [bar] Particle mass [mg] Bulk density [kg / m 3 ] Example 5 Example Mat. 2 24 122 23 26,0 32 105 Example 6 Example Mat. 3 24 127 30 29,3 32 72 See Example 8 Ref. Mat. 2 24 128 3 30,4 32 131 See Example 9 Ref. Mat. 3 24 135 3 34,7 32 142

[0088] The expanded granules were then welded together by exposure to steam on a Kurtz ersa GmbH Boost Foamer molding machine to form square sheets with a side length of 200 mm and a thickness of 10 mm. The welding parameters for the different materials were selected so that the sheet side of the final molded part, which faced the moving side of the mold, had the lowest possible number of collapsed ETPU particles. Gap vapor deposition was also carried out through the moving side of the mold where necessary. Achieving a satisfactory surface quality was not always possible with the comparative examples. The different temperatures and vapor deposition times for the examples and the comparative examples were necessary to produce comparable sheets. Under the same conditions, the particles of the comparative examples were either not welded homogeneously or had collapsed at the surface.Regardless of the test, a cooling time of 120 s was always set at the end of the test on both the fixed and movable sides of the mold. The respective vapor deposition conditions are listed in Table 9 as vapor pressures and in Table 10 as corresponding vapor temperatures. This results in a lower maximum vapor pressure required to weld the polyurethane particles of the examples compared to those of the comparative examples. Table 9: Steam pressures and welding times for the materials of the examples and comparative examples Gap vapor deposition (bar) Gap vapor deposition (s) Transverse steam fixed side (bar) Transverse steam fixed side (s) Transverse steam movable side (bar) Transverse steam moving side (s) Autoclave steam fixed / movable side (bar) Autoclave steam (s) Example 5 1 20 1,9 4 1,9 7 1,9 / 1,9 32 Example 6 1 20 2,5 10 2,5 13 2,5 / 2,5 32 See Example 8 1 20 2,4 3 2,4 3 2,4 / 2,4 48 See Example 9 1 20 3,2 3 3,2 3 3,2 / 3,2 48 Table 10: Steam temperatures (measured at the tool) and times for welding the materials of the examples and comparative examples Gap vapor deposition (°C) Gap vapor deposition (s) Transverse steam fixed side (°C) Transverse steam fixed side (s) Transverse steam moving side (°C) Transverse steam moving side (s) Autoclave steam fixed / movable side (°C) Autoclave steam (s) Example 5 120 20 132 4 132 7 132 / 132 32 Example 6 120 20 138 10 138 13 138 / 138 32 See Example 8 120 20 137 3 137 3 137 / 137 48 See Example 9 120 20 144 3 144 3 144 / 144 48

[0089] To analyze the weld quality, the tensile strength of the samples was tested. This was determined for a panel thickness of 10 mm based on ASTM D5035:2015, which was developed for textiles. The values ​​are listed in Table 11. Table 11: Tensile test results of the welded plates of the examples and comparative examples (plate thickness 10 mm) Board density (kg / m 3< ) Tensile strength (kPa) Elongation at break (%) Example 5 203 580 ± 10 65 ± 7 Example 6 147 530 ± 70 53 ± 9 See Example 8 307 587 ± 100 74 ± 15 See Example 9 240 503 ± 80 58 ± 13

Claims

1. An expanded thermoplastic polyurethane bead polymerized from an isocyanate, a polyol as isocyanate-reactive compound having a number-average molecular weight between 500 and 10 000 g / mol and a chain extender, wherein customary adjuvants may be additionally present, the thermoplastic polyurethane has a hard phase fraction in the range from 0.15 to 0.5 and the hard phase fraction is defined by Hard phase fraction = ∑ x = 1 k m KVx M KVx ⋅ M Iso + m KVx m ges where - MKVx: molar mass of chain extender x in g / mol, - mKVx: mass of chain extender x in g - MIxo: molar mass of isocyanate used in g / mol - mtot: total mass of all starting materials without adjuvants - k: number of chain extenders, and the chain extender is a diol having 5 to 10 carbon atoms, a mixture of two or more differing diols wherein one or more than one diol has 4 to 10 carbon atoms and all further diols have 2 to 10 carbon atoms, a mixture of one or more than one diol having 4 to 10 carbon atoms and one or more than one diamine or a mixture of one or more than one diol having 4 to 10 carbon atoms and an aminoalcohol.

2. The expanded thermoplastic polyurethane bead according to claim 1 wherein the isocyanate is selected from trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, octamethylene diisocyanate; 2-methylpentamethylene 1,5-diisocyanate; 2-ethylbutylene 1,4-diisocyanate; butylene 1,4-diisocyanate; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; 1,4-bis(isocyanatomethyl)cyclohexane; 1,4-cyclohexane diisocyanate; 1-methyl-2,4-cyclohexane diisocyanate; 1-methyl-2,6-cyclohexane diisocyanate; 2,2'-dicyclohexylmethane diisocyanate; 2,4'-dicyclohexylmethane diisocyanate; 4,4'-dicyclohexylmethane diisocyanate; 2,2'-diphenylmethane diisocyanate; 2,4'-diphenylmethane diisocyanate; 4,4'-diphenylmethane diisocyanate; 1,5-naphthylene diisocyanate; 2,4-tolylene diisocyanate; 2,6-tolylene diisocyanate; diphenylmethane diisocyanate; 3,3'-dimethylbiphenyl diisocyanate; 1,2-diphenylethane diisocyanate and phenylene diisocyanate and also any desired mixture thereof.

3. The expanded thermoplastic polyurethane bead according to claim 1 or 2 wherein the polyol as isocyanate-reactive compound is selected from polyetherols, polyesterols, polybutadienols and polycarbonateols and their mixtures and also block copolymers thereof.

4. The expanded thermoplastic polyurethane bead according to any one of claims 1 to 3 wherein in the case of just one chain extender the chain extender is selected from the group consisting of 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclohexyldimethanol, 2-butyl-2-ethylpropanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, pinacol, 2-ethyl-1,3-hexanediol, 1,4-cyclohexanediol and N-phenyldiethanolamine.

5. The expanded thermoplastic polyurethane bead according to any one of claims 1 to 3 wherein, when a mixture of two or more differing diols is used, the proportion of the diol having 4 to 10 carbon atoms is in the range from 0.001 to 50 wt% based on total chain extender mass.

6. The expanded thermoplastic polyurethane bead according to claim 5 wherein the first diol is selected from 1,4-butanediol and 1,6-hexanediol and all further diols are selected from 1,2-ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,4-cyclohexyldimethanol, 2-butyl-2-ethylpropanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, pinacol, 2-ethyl-1,3-hexanediol, 1,4-cyclohexanediol and N-phenyldiethanolamine, wherein the first diol and all further diols differ.

7. The expanded thermoplastic polyurethane bead according to any one of claims 1 to 6 wherein the expanded thermoplastic polyurethane is closed cell and has a cell size in the range from 1 to 250 µm, wherein the cell size is quantifiable visually from micrographs.

8. The expanded thermoplastic polyurethane bead according to any one of claims 1 to 7 wherein the expanded thermoplastic polyurethane is in the form of beads having a maximum longitudinal dimension of 1 to 25 mm.

9. A process for producing the expanded thermoplastic polyurethane bead according to any one of claims 1 to 8, comprising the following steps of: (a) reacting an isocyanate with a polyol as isocyanate-reactive compound and a chain extender optionally in the presence of one or more catalysts and / or adjuvants to form a polyurethane, wherein the amounts of isocyanate, of polyol as isocyanate-reactive compound and of chain extender are adjusted such that the thermoplastic polyurethane has a hard phase fraction in the range from 0.15 to 0.5 and the hard phase fraction is defined by Hard phase fraction = ∑ x = 1 k m KVx M KVx ⋅ M Iso + m KVx m ges where - MKVx: molar mass of chain extender x in g / mol, - mKVx: mass of chain extender x in g - MIxo: molar mass of isocyanate used in g / mol - mtot: total mass of all starting materials without adjuvants - k: number of chain extenders, and the chain extender is a diol having 5 to 10 carbon atoms, a mixture of two or more differing diols wherein one or more than one diol has 4 to 10 carbon atoms and all further diols have 2 to 10 carbon atoms, a mixture of one or more than one diol having 4 to 10 carbon atoms and one or more than one diamine or a mixture of one or more than one diol having 4 to 10 carbon atoms and an aminoalcohol, (b) impregnating the polyurethane with a blowing agent, (c) depressurizing the blowing agent-impregnated polyurethane into the expanded thermoplastic polyurethane, wherein the polyurethane is impregnated with the blowing agent in an extruder, the impregnated polyurethane is cut into a pellet material and the pellet material is depressurized immediately after cutting into expanded thermoplastic polyurethane beads, or the polyurethane produced in step (a) is cut into a pellet material, the pellet material is impregnated in a tank or in an autoclave with 0.1 to 40 wt% of a blowing agent at a temperature in the range from 100 to 180°C and a pressure in the range from 5 to 100 bar and then the blowing agent-containing pellet material is foamed by depressurization.

10. The process according to claim 9 wherein the producing of the polyurethane in step (a) is carried out in a first extruder or a first extruder part and the impregnating of the melt is carried out in a second extruder or a second extruder part, the impregnated polyurethane is cut into a pellet material and the pellet material is depressurized immediately after cutting into expanded thermoplastic polyurethane beads.

11. A process for producing a molded part from the expanded thermoplastic polyurethane beads according to any one of claims 1 to 8, comprising the following steps of: (a) introducing the expanded thermoplastic polyurethane beads into a mold, and (b) subjecting the expanded thermoplastic polyurethane beads introduced into the mold to steam, hot air or high-energy radiation whereby the expanded thermoplastic polyurethane beads incipiently melt at the surface and fuse together to form the molded part.

12. The process according to claim 11 wherein the molded part is a shoe sole, a gymnastics mat, a body protector, a trim element in automotive construction, a sound absorber, a vibration absorber, a cushioning pad, a bicycle saddle, a toy, a tire or a tire part or a surface for an athletic running track, a sports hall or a footpath, a damping layer or a damping core in a sandwich element or a packaging item.