MXPA99011893A - Polyurethane aliphatic thermoplastics, procedures for your obtaining and your - Google Patents

Abstract

The present invention relates to: A composition for molding, characterized in that it comprises: a thermoplastic, aliphatic polyurethane which is the product of reacting only an aliphatic diisocyanate containing from 60 to 100% in mol of hexamethylene diisocyanate and from 0 to 40% in mole of at least one different aliphatic diisocyanate, at least one polyol having a number average molecular weight of 600,000 g / mol selected from the group consisting of polyester polyols, polyester polyols and polycarbonate diols, and a chain-lengthening reagent having an average molecular weight of 60 to 500 g7mol, where the equivalent ratio of the aliphatic diisocyanate to at least one polyol is 1.5: 1.0 to 10.0: 1.0, the NCO index is 95 to 105, the pliurethane has a Shore A hardness value from 75 to 92 and a softening temperature higher than 100 ° C, the softening temperature being determined by dynamic-mechanical analysis in traction mode E'= Mpa, the hardness value being referred to measurements both pre-post-exposure to weathering and where polyurethane having a Shore A hardness of 85 to 94 and a softening temperature of less than 130 ° C is excluded; a UV stabilizer that is present in an amount of 0.4 to 0.9 percent relative to the total weight of the polyurethane, where the weathering composition determined after 504 hours in accordance with ISO 4892 of less than

Description

ALIPHATIC THERMOPLASTIC POLYURETHANES, PROCEDURES FOR THEIR OBTAINING AND USE THEREOF Field of the Invention The invention relates to aliphatic thermoplastic polyurethanes (TFU) of improved properties, to processes for obtaining and using them. Aromatic thermoplastic polyurethanes (Aromatic TPU) are not photostable because they are composed of aromatic diisocyanates. By adjusting the color of the molding bodies a strong arillation arises due to the effect of light and even, in black molding bodies, there is a change in the gradation of brightness and color.

Background of the Invention DE-C 42 03 307 discloses a thermoplastic polyurethane molding composition which can be prepared in the form of a sintered powder for the production of granulated sintered sheets, in which the powder is obtained exclusively from linear aliphatic components. The components REF .: 32378 polyols are composed of 60 to 80 parts by weight of aliphatic polydiolcarbonate with a molecular mass Mn of 2,000 and 40 to 20 parts by weight of a polydiol based on adipic acid, hexanediol and neopentyl glycol with a molecular weight of , of 2,000. 1,6-hexamethylene diisocyanate is used in an equivalents ratio of 2.8: 1.0 to 4.2: 1.0, based on the mixture of polyols, and 1, -butanediol as a chain extender, increasing the ratio of equivalents of 1, -butanediol referred to the mixture of polyols a from 1.3: 1.0 to 3.3: 1.0. This molding compound has the disadvantage that, after storage (at room temperature and especially after an accelerated aging test, such as the climate change test, the Arizona test and with heating (60-95 ° C)), it tends to to the formation of a white patina. This is a disadvantage especially for optically demanding applications. US Patent 5,824,738 discloses a photostable aliphatic TPU which, after intensive artificial exposure to the weather, shows very little yellowing. The photostable TPU described is comprised on one side by a critical combination of UV stabilizer, antioxidant agent and pigment, and on the other hand of a polyether based on propylene oxide with end groups of ethylene oxide, dicyclohexylmethane diisocyanate (MDI hydrated = H? _- MD1) and 1,4-butanediol. This photostable TPU based on H: _- MDI has the disadvantage of showing a relatively low thermal stability, which is especially disadvantageous for uses, for example in the area of automobile assembly lines, where a greater thermal stability. Therefore, the function of the present invention was to provide both photostable and thermostable thermoplastic polyurethanes, as well as a process for obtaining them. For high optical demands, as for example in the area of automobile assembly lines, the function is also to provide a TPU that after storage at room temperature and especially after an accelerated aging test (for example after storage at 60 a 95 ° C) provide a molding body showing little or no patina formation.

This function could be solved with the thermoplastic polyurethanes according to the invention.

Description of the Invention The subject of the present invention are aliphatic thermoplastic polyurethanes with a ama i 11 eami ent < 20 preferably < 15 after a weather exposure of 504 hours according to IS04892 and with a softening temperature (measured by means of dynamic-mechanical analysis (DMS) in traction mode, which is described in more detail below) Treb (with E '= 3 MPa) > 100 ° C for thermoplastic polyurethanes with a hardness of 75 to 84 Shore A and with a softening temperature (measured by dynamic-mechanical analysis (DMS) in traction mode, described in more detail below) TIot. { with E '= 3 MPa) > 130 ° C for thermoplastic polyurethanes with a hardness of 85 to 98 Shore A, both before and after 504 hours of exposure to the weather according to IS04892. Preferred are the aliphatic thermoplastic polyurethanes according to the invention obtained from: A) from 100 to 60% by mole, preferably from 100 to 70% by mole, especially preferred from 100 to 80% by mole of hexamethylene diisocyanate (HDI) and from 0 to 40% by mole, preferably from 0 to 30. "in moles and especially preferred from 0 to 20. in moles of another aliphatic diisocyanate B) Polyolyester with an average molecular weight of between 600 and 5,000 g / mol, preferably between 700 and 4200 g / mol C) Chain extender with a molecular mass average of 60 to 500 g / mol D) UV stabilizers in an amount of 0.4 to 0.9% by weight, preferably from 0.4 to 0.8 =? by weight, referred to A) + B) + C) E) Catalysts, where appropriate, and- F) Conventional adjuvants and additives, where appropriate, in which the ratio of equivalents of diisocyanate A) to polyol B) amounts to between 1.5: 1.0 and 10.0: 1.0 and in which the NCO index (formed by the quotient of the equivalents of the isocyanate groups and the sum of the hydroxyl groups of the polyols and extenders of the chain multiplied by 100) amounts to 95 to 105.

The aforementioned order of the components A to F does not indicate the way of obtaining the TPU according to the invention. The TPUs according to the invention can be obtained with different variants of the process, these variants being equivalent to each other. The TPUs according to the invention can be obtained for example (see also pages 17-24 of the specification) based on two different aliphatic diisocyanates "Al" (HDI) and "A2" (aliphatic diisocyanate), in a reaction process for give the TPU "Al-2". However, it is also possible to obtain, in a known manner, first the TPU "Al" based on the aliphatic diisocyanate '? L "and, separately, the TPU" A2"based on the aliphatic diisocyanate" A2", being the usual components Identical B to F. The "Al" TPU and "A2" TPU are then mixed in a known manner in the desired ratio to give the "Al -2" TPUs (e.g. by extrusion or molding) TPUs according to the invention can obtain also based on mixtures of polyols by using mixtures of polyols (polyol Bl and polyol B2) (for example mixing aggregates) in a reaction process (see also pages 17 to 24) to give the TPU "Bl-2 On the other hand, the TPU "Bl" based on the polyol "Bl" and separately the TPU "B2" based on the polyol "B2" can be obtained in a known manner, with the remaining components A and C to identical F. Then TPU "Bl" and TPU "B2" can be mixed in a known manner in the desired ratio to give the TPU "Bl -2"(for example with extruders or mixers). Instead of the polyester polyol B), the following polyols can be used: polyether polyols with an average molecular weight between 600 and 5,000 g / mol, preferably between 700 and 4200 g / mol, polydiolcarbonates with an average molecular weight between 600 and 5.00 g / mol, preferably between 700 and 4200 g / mo, polyolether / polyester mixture having an average molecular weight between 600 and 5,000 g / mol, preferably between 700 and 4200 g / mol, polyether / polydiol carbonate mixture with an average molecular mass of 600 and 5,000 g / mol, preferably between 700 and 4,200 g / mol, polyester / polydiol carbonate mixture with an average molecular mass between 600 and 5,000 g / mol, preferably between 700 and 4200 g / mol.

Preferably, a mixture of 20 to 80 parts by weight of an aliphatic polydiolcarbonate having an average molecular weight of 1,000 to 2,200 g / mol and 80 to 20 parts by weight of a polybutadiene tobutanediol or a polydiolcaprolactone with a mass is used as the polyol component. molecular weight from 1,000 to 2,400 g / mol. Especially preferred are polyol components composed of a mixture of 30 to 70 parts by weight of an aliphatic polydiol carbonate having an average molecular weight of 1.00 to 2.200 g / mol and 70 to 30 parts by weight of a polyadipanadane tobutane diol or a polydiolcaprolactone. with a molecular mass of 1.00 to 2.400 g / mol. In case the part of polyadipatobutanediol in the polyol mixture amounts to more than 50% and with strict hydrolysis requirements, known polyadipatebutanediol (for example carbodiimides) should be added to the polyadipatebuto-diol.

Suitable UV stabilizers are described in R. Gáchter, H Müller Ed Taschenbuch der Kunstof f-Additive, 3"Ed., Hanser Verlag, Munich 1989, Cap." Poiyurethane. "As UV stabilizers, it is especially preferred to use a mixture of amines stabilizers (HALS) and hydroxy-phenylenediazole, with impairment spherical, in a weight ratio of 2: 1 to 1: 2. According to the requirements of the molding piece, which is obtained from the TPU according to the invention, part of the hexameter and the end product can be used (HDI). ) against one or more aliphatic diisocyanates, especially iso-fordo-isocyanate (IPDI), 1,4-cyclohexanediisocyanate, 1-methyl-2, -cyclohexanediisocyanate, 1-methyl-2,6-cyclohexanediisocyanate and mixtures of these isomers, , 4'-, 2,4'- and 2,2'-dicyclohexylmethane anodiisocyanate and mixture of these isomers Particularly preferred thermoplastic polyurethanes according to the invention are obtained from: TO! 95-70 mol% hexamethylene diisocyanate (HDI) and 5 to 30 mol% other aliphatic diisocyanate B: Polyester, polyether polyol, polydiol carbonate, a mixture of polyether polyol ether, a mixture of polyether polyols and polydiol carbonate or a mixture of polyol This is and polydiolcarbonate with a respective average molecular weight of between 600 and 5,000 g / mol, preferably between 700 and 4200 g / mol c: Chain extender with an average molecular weight of 60 to 500 g / mol D: UV stabilizers in an amount of 0.4 to 0.9% by weight, preferably 0.4 to 0.8 by weight, based on A) + B) + C) • E: Catalysts, where appropriate and F: Coadjuvants and conventional additives, where appropriate, in which the ratio of equivalents of diisocyanate A) to polyol B) is between 1.5: 1.0 and 10.0: 1 and in which the NCO index (formed by the quotient) of the equivalent ratios of the isocyanate groups and the sum of the hydroxyl groups of the polyols and chain extenders multiply per 100) amounts to 95 to 105, and showing a test body obtained from the thermoplastic polyurethane only a very low patina (enti zamiento) formation on the surface also after storage between 60 and 95 ° C for three weeks . Especially preferred are also thermoplastic polyurethanes according to the invention which are obtained from: A) from 100 to 60% by mole, preferably from 100 to 70% by mole, especially preferred from 100 to 80% by mole of hexamethylene diisocyanate (HDI) and from 0 to 40% by moles, preferably from 0 to 30-moles and especially preferred from 0 to 20. ' in moles of another aliphatic diisocyanate B) Polyol ester, polyether polyol ether, polydiol carbonate, a mixture of polyether polyol ether and polyol ester, a mixture of polyether polyol ether and polydiol carbonate or a mixture of polyester ester and polydiol carbonate having an average molecular weight of respectively between 600 and 5,000 g / mol C ) From 80 to 100% by weight of 1,6-hexanediol and from 0 to 20% by weight of chain extender with an average molecular weight of 60 to 500 g / mol.

D) UV stabilizers in an amount of 0.4 to 0.9% by weight, preferably 0.4 to 0.8 by weight, based on A) + B) + C) E) Catalysts, where appropriate and F) Where applicable, coadjuvants and conventional additives, in which the equivalent ratio of diisocyanate A) to polyol B) amounts to between 1.5: 1.0 and 10.0: 1.0 and in which the NCO index (formed by the quotient of the equivalent ratios of the isocyanate groups and the sum of the hydroxyl groups of the polyols and chain extenders multiplied by 100) is from 95 to 105, and a test body obtained from the thermoplastic polyurethane shows only a poor patina (enti zamiento) formation on the surface as well. after storage between 60 and 95 ° C for three weeks. In applications with low photographic stability requirements, for example dark colored molding compositions, part (from 0 to 20 by weight) of the aliphatic diisocyanate can be replaced by aromatic diisocyanates. These are described in Justus Liebigs Annalen der Chemie 562, p. 75-136. Examples: 2, 4- toluylene diisocyanate, mixture of 2,4- and 2,6-toluylene diisocyanate, 4,4'-, 2,2'- and 2,4'-diphenylmethane diisocyanate, mixture of 2,4- and 4,4 '-diphenylmethane diisocyanate, 2,4- and / or 4,4'-di-phenylmethane diisocyanate modified with urethane, 4,' -di-phenylethane (1,2) diisocyanate, and 1,5-naphthalene diisocyanate. As component B) linear polyols terminated in hydroxyls with an average molecular weight of 600 to 5,000 g / mol, preferably from 700 to 4200 g / mol are used. For production reasons they often contain small amounts of non-linear compounds. This is why "essentially linear polyols" are normally used. Suitable polydiolyes can be obtained, for example, from dicarboxylic acids having 2 to 12 carbon atoms, preferably from 4 to 6 carbon atoms, and functional multi- alcohols. Suitable dicarboxylic acids are: aliphatic dicarboxylic acids, such as succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid and sebacic acid and aromatic dicarboxylic acids, such as phthalic acid, isophthalic acid and terephthalic acid. The di-carboxylic acids can be used alone or as mixtures, for example in the form of a mixture of succinic, glutaric and adipic acids. In order to obtain the pyridolyesters, it may be advantageous, instead of dicarboxylic acids, to use the corresponding derivatives of carboxylic acids, such as diesters of carboxylic acids with 1 to 4 carbon atoms in the alcohol moiety, carboxylic acid anhydrides. or chlorides of carboxylic acids. Examples of multi-functional alcohols are glycols of 2 to 10, preferably 2 to 6 carbon atoms, such as ethylene glycol, diethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol, 2,2-dimet i 1-1, 3-propanediol, 1,3-propanedio 1 and dipropylene glycol. According to the desired properties, the multifunctional alcohols can be used alone or, if appropriate, as a mixture between them. In addition, carbon dioxide esters are suitable with the aforementioned dioids, especially those with 4 to 6 carbon atoms, such as 1,4-butodiol or 1,6-hexanediol, condensation products of hydroxycarboxylic acids, for example hydroxycaproic acid and lactone polymerization products, for example, optionally substituted caprolactones. Polydiolyesters are preferably ethanediol polyadipate, polyadipate 1-butanediol, ethanediol-1,4-butanediol polyadipate, 1,6-hexanediol-neopentyl glycol polyadipate, 1,6-hexanediol-1,4-butanediol polyadipate and pol i capro 1 actona. The polydiolyesters have average molecular masses of 600 to 5,000, preferably 700 to 4,200 and can be used alone or in the form of mixtures. Suitable polydiol ethers can be obtained by reacting one or more alkylene oxides of 2 to 4 carbon atoms in the alkyl moiety with a starter molecule containing 2 active hydrogen atoms attached. Suitable alkylene oxides are, for example, ethylene oxide, 1,2-propylene oxide, epi-chlorohydrin, 1,2-butylene oxide and 2,3-butyl oxide. Preference is given to using ethylene oxide, propylene oxide and mixtures of 1,2-propylene oxide and ethylene oxide. The alkylene oxides can be used alone, alternating or as mixtures. As initiator molecules, for example: water, aminoalcohol, such as N-alkyl-diethanolamines, for example N-methyl-diethanolamine and diols, such as ethylene glycol, 1,3-propylene glycol, 1,4-butanediol and 1,6-diol. -hexanodiol. If appropriate, mixtures of initiator molecules can also be used. Polydiol ethers are also suitable, the polymerization products containing hydroxyl groups of tetrahydrofurans. It is also possible to use trifunctional polyethers in proportions of 0 to 30% by weight, based on bi-functional polyethers, but at most only in an amount which produces a processable product such as thermoplastic. Polymers are essentially linear and have a molecular mass of 600 to 5,000, preferably from 700 to 4,200. They can be used either alone or in the form of mixtures. Especially preferred are polymerization products containing hydroxyl groups of tetrahydrofurans and polyether alcohols based on ethylene oxide and / or propylene oxide. The partial use of these preferred polydiol ethers in blends of polyols, in particular with 1, 6-hexanediol as a chain extender, gives rise to TPU which after accelerated aging tests (for example after storage at 60 to 95 ° C) show only one scarce patina formation on the surface.

As the chain extender C), aliphatic diols or diamines with a molecular weight of 60 to 500, preferably aliphatic diols with 2 to 14 carbon atoms, such as, for example, ethanediol, 1,6-hexanediol, diethylene glycol, dipropi lengl i col and especially 1, -butanediol or diamines (cyclo) to ifáticas, such as for example isophorone diamine, eti lendiamine, 1,2-propylenediamine, 1,3-propylenediamine, N-methyl-propyl-1, 3-diamine, N, N '-dimeti let i lendiamine. It is also possible to use mixtures of the chain extenders mentioned above. In addition, small amounts of triols can be added, however at most only in an amount such that they give rise to a processable product such as thermoplastic. Especially preferred as chain extender is 1,6-hexanediol, optionally mixed with up to 20% by weight of chain extender with an average molecular weight of 60 to 500 g / mol, since the TPU obtained with 1, 6 -hexanodiol or the test bodies obtained with them show only a poor patina formation on the surface after accelerated aging tests (for example, after storage between 60 and 95 ° C).

In applications with low photostability requirements, for example dark colored molding compositions, part (from 0 to 80 * by weight) of the aliphatic diols and diamines (from 0 to 20%) can be replaced by aromatic diols and diamines. Examples of suitable aromatic diols are diesters of terephthalic acid with glycols of 2 to 4 carbon atoms, such as, for example, terephthalic acid-bis-ethylene glycol or terephthalic acid-β-1,4-butanediol, hydroxyalkylene ether of hydroquinone, for example 1,4-di (hydroxyethyl) hydroquinone and ethoxylated bisphenols. Examples of suitable aromatic diamines are 2, 4-tolu lend? Amma and 2, 6-tolui 1 endine amine, 3,5-diet 11-2, 4-tolui 1 endiamine and 3, 5-d? Et 11 -2 , 6-toluylenediamine and 4, mono-, di, tri or tetra-substituted primary diaminophenylmethanes with alkyl. In addition, conventional monofunctional compounds can also be used in small amounts, for example to interrupt the chain or as mold release adjuvants. For example, alcohols such as octanol and stearyl alcohol or amines such as butylamine and tearylamine are indicated.

Another object of the invention is a process for the continuous production of the thermoplastic polyurethanes of the invention, characterized in that the polyol / mixture of polyols B) and the chain extender C) are mixed continuously and then intensively mixed with the diisocyanate / diisocyanate mixture A) (one-step process) and finally the reaction is carried out in a delivery container (for example in an extruder) and the product contained therein is granulated. Preferably the reaction is carried out in the presence of a catalyst. The mixture of polyol (B) and chain extender (C) is mixed homogeneously with the diisocyanate (A) preferably in a reactor in a time interval of at most 5 seconds. Preferably the complete mixture with small backmixing should be achieved. A small backmixing in the sense of this invention means that the behavior of residence time in the reactor corresponds to a series of 10 or more ideal agitation tank (cascade of agitation tanks). A complete homogenous mixture in the sense of the present invention means that the distribution of concentrations of the components (A) - * - (B) * (C) and the reaction product in the mixture shows a relative standard deviation of less than 5%. Before continuously introducing the components (A) and (B) + (C) into the reactor, they should be heated alone, preferably in a heat exchanger, at a temperature between 60 and 150 ° C, preferably between 80 and 120 ° C. According to the invention it is essential that the temperatures of the components (A) and (B) + (C) before grouping in the reactor differ by less than 20 ° C. Preferably the temperature difference between the component streams' (A) and (B) + (C) should be <10 ° C, especially preferred < 5 ° C. The mixture thus obtained is then reacted in any reactor, preferably in an extruder or a reaction tube, to give TPU. According to the invention of polyaddition it is preferably carried out in an isolated static mixer and preferably with heating means. This has the advantage that it does not show any moving part and that a complete homogenous mixture is obtained, almost free of back-mixing in the shortest time. The static mixers which can be used according to the invention are described in Chem.-Ing. Techn. 52_, No. 4 on pages 285-291, as well as in "Mischen von Kunstoff und Kautschukprodukten", VDI-Verlag, Dusseldorf 1993 Static mixers are preferably used according to DE-C 2328795. Static mixers preferably have a length / diameter ratio of 8: 1 to 16: 1, especially preferred of 10: 1 14: 1. A residence time is obtained in the static mixer < 5 seconds, preferably < 2.5 seconds. The static mixer is preferably manufactured in steel, especially preferred in V4A. Another object of the invention is a continuous production process of the thermoplastic polyurethanes of the invention, characterized in that the polyol / mixture of polyols B) and the chain extender C) are mixed continuously, then brought to full reaction with hexame ti 1 endi isocyanate, then mixed with the other aliphatic diisocyanate (second) and reacted, the reaction is terminated in a delivery container and the product is granulated, if appropriate. This process variant is especially preferred. The process can also be carried out so that the mixture is reacted with the other aliphatic diisocyanate (second), then mixed with hexameti lendi isocyanate and reacted and the reaction is terminated in a delivery container and the product in its case is granulated. The thermoplastic polyurethanes according to the invention can also be obtained according to the prepolymer process in which the diisocyanate / mixture of diisocyanates is first mixed with the polyol / polyol mixture and reacted until a prepolymer is obtained, this prepolymer is mixed in a second stage with the chain extender and reacted. Preferably a catalyst is used in the continuous production of the thermoplastic polyurethanes by means of the extrusion process or tape. Suitable catalysts are conventional tertiary amines known in the state of the art, such as for example triethylamine, dimethylcyclohexylamine, N-methylmorpholine, N, N'-dimethylpiperazm, 2- (dimethylammoethoxy) ethanol, diazabicyclo- [2, 2, 2] -octane and the like, as well as especially organometallic compounds such as titanic acid ester, iron compounds, tin compounds, for example tin acetate, tin octoate, tin dilaurate or the dialkyltin salts of aliphatic carboxylic acids such as dibutyltin diacetate , dibutyltin dilaurate or the like. The preferred catalysts are organometallic compounds, especially titanic acid esters, iron or tin compounds. Dibutyltin dilaurate is especially preferred. In addition to the TPU components, UV stabilizers and, where appropriate, catalysts, adjuvants and additives may also be added. For example, glidants such as fatty acid esters, their metal soaps, fatty acid amides, silicone compounds, laminar anti-adhesion agents, inhibitors, stabilizers against hydrolysis, heat and decoration, flame retardants, dyes, pigments, fillers are indicated. inorganic and organic and reinforcing; which are obtained according to the state of the art and which can also be applied in the form of a layer. More detailed data can be obtained on the adjuvants and additives mentioned in the literature, for example JH Saunders, KC Frisch: "High Polymers", Vol. XVI, Poiyurethane, parts 1 and 2, Interscience Publishers 1962 or 1964, R. Gáchter , H. Müller (Ed.): Taschenbuch der Kunstoff-Additive, 3rd Ed., Hanser Verlag, Munich 1989 or in DE-A-2901774. The glidants are preferably added in an amount of 0.1 to 1.0% by weight based on A) + B) + C). The antioxidants are preferably used in amounts of 0.1 to 0.7% by weight, based on A) + B) + C). The TPUs according to the invention are preferably obtained continuously by mixing the polyol / polyol mixture and the chain extender continuously (for example by means of a static mixer) and this mixture is mixed with HDI (for example by static mixer) and they react In another stage, the second diisocyanate other than HDI is mixed (if any). The mixture of the second diisocyanate can take place by for example static mixer, tube mixer or also in extruder. The mixture can be reacted completely, for example in an extruder and finally granulated.

The polyol-chain extender mixture and the diisocyanate should preferably show a temperature difference before mixing. 20 ° C, preferably < 10 ° C, especially preferred < 5 ° C The absolute temperature of the raw material is preferably between 60 ° C and 150 ° C, especially preferred between 80 ° C and 120 ° C. The second diisocyanate other than HDI can be reacted first with the polyol-chain extender mixture. The HDI is then mixed and also reacted. The addition of additives can take place after the polymerization by "compounding" or also during the polymerization. During the polymerization, for example antioxidants and UV stabilizers can be dissolved in the polyol. The gliders and stabilizers can also be added in the extrusion process, for example in the second part of the propeller. The whitish patina formation on the surface that appears with the accelerated aging tests (for example storage at 60 to 95 ° C) in the TPU molding bodies can be especially avoided by partially replacing the hexamethylene diisocyanate used in the TPU according to the invention. other aliphatic diisocyanates. This patina formation can be avoided by using chain extender mainly 1,6-hexanediol. The TPUs according to the invention can be used for the production of mold bodies, in particular for the production of extrudates (for example sheets) and injected castings. They are preferred for their properties in the area of automobile assembly lines. The TPUs according to the invention can also be used as a sinterable powder for obtaining flat articles and hollow bodies. The invention is made clearer by the following examples.

Examples Obtaining TPU and injection plates The TPUs are obtained continuously in the following manner: The mixture of polyol B) - chain extender C) and dibutyltin diurate was heated in a tank with stirring at about 110 °. C together with the corresponding diisocyanate, which by means of a heat exchanger was heated to around 110 ° C, was agitated intensively in a static mixer of the company Sulzer (DN6 with 10 mixing elements and a cutting speed of 500 s '1) and then it was brought to the entrance of a propeller (ZSK 32). As a result it was necessary to feed the second diisocyanate other than HDI in zone 1 of the helix (ZSK 32). The aforementioned mixture reacted in the extruder until complete reaction and finally granulated. The corresponding granulate was dried and then injected obtaining several injection plates. A part of the injection plates was in turn stored in a drying chamber with air recirculation at 85 ° C and the formation of patina on the surface was determined. The patina formation is especially easy to recognize in the fingerprints that are in the molding body. The result of the tests is considered qualitatively, since no measurement procedure is known. The other part of the injection plates was subjected to the exposure to the weather described below. Finally, the yellowing and the modulus of elasticity were measured with temperature.

DBTL: Dibutyltin dilaurate DE2020: Polydiolcarbonate based on 1,6-hexanediol of average molecular mass Mn = 2000 g / mol PE225B: Polyadipatebuto-diol of average molecular mass Mn = 2.250 g / mol l, 4BDO: 1,4-butanediol PE100B: Polyadipabutobutane diol Mn = 1,000 g / mol Terathane 2000 (R): Polydioltetrahydrofuran of Mn = 2,000 g / mol (Company DuPont) Terathane 1000 (R): Polydioltetrahydrofuran of Mn = 1.0 g / mol (Company DuPont) HDI: Hexamethylene diisocyanate IPDI: Isoforondiisocyanate H? 2-MDI: Isomer mixture of dicyclohexylmethane diisocyanate April (R) 10 DS Bis-stearylamide (Co. ürtz GmbH) Irganox (R) 1010: Tetrakis [methylene- (3,5-di-tert-butyl-4-hydroxyhydrocinnamate] methane (Co Ciba Geigy).

Tinuvin (R) 328: 2- (2'-Hydroxy-3'-5'-di-tert-amylphenyl) benzotriazole (Co. Ciba Geigy). Tinuvin (R) 622: Dimethylsuccinate polymer with 4-hydroxy-2, 2,6,6,6-tetramethyl-1-piperidinetanol (Co. Ciba Geigy).

Loxiol (R) G78: Stearic acid (Co. Hoechst) Acrawax (R) C: Bis-stearylamide (Co. Lonza) 1,6 HDO: 1,6-hexanediol Tinuvin (R) 213: Poly (oxy-1,2-ethanediyl ), (a- (3- (3 - (2H-benzotriazol-2-yl) -5,11, -dimethylethyl) -4-hydroxyphenyl) -1- oxopropoxyl) -omega - (3- (3- ( 2H-benzotriazol-2-yl) -5- (1,1-dimethylethyl) -4-hydroxyphenyl) -1- oxopropoxy, main component (Co. Ciba Geigy) Tinuvin (R) 765: Bis (1, 2, 2, 6, 6-pentamethyl-4-piperidinyl) sebacate, main component (Co. Ciba Geigy) Irganox (R) 245: Ethylenebis (oxyethylene) bis-3-tert-butyl-4-hydroxy-5- (methylhydrocinnamate) ( Co. Ciba Geigy) Summary of TPU (thermoplastic polyurethanes) * The amounts of reagents are given in moles and grams (mol / g).

The TPU from 1 to 4 and from 10 to 16 contain 0.3% by weight of April (R) 10DS, 0.3% by weight of Irganox (R) 1010, 0.4% by weight of Tinuvin ( R) 328 and 0.4% by weight of Tinuvin® 622, respectively referred to TPU. The content of DBTL refers to the mixture of polyols. TPU 16 contains 0.75 moles (78 g) of neopentyl glycol (2,2-dimethyl-l, 3-propanediol). TPU 15: HD0: BD0: 80: 20 (Ratio of the percentages in moles) TPU 16: HDO: Neopentyl glycol = 80:20 (Ratio of the percentages in moles) Results The TPU 5 to 9 and 17 as well as the comparisons 1 and 2 also contain the following additives: Results Summary of the TPU TPU 17 contains as chain extender l, 6HDO (1.84 moles, 217 g). * The amount of reagents is given in moles and grams (mol / g).

Condition »of essays From the TPU, rectangular injection plates (125 mm x 50 mm x 1 mm) were obtained.

Dynamic-ecomanic analysis (DMS) Rectangles 30 mm x 10 mm x 1 mm were stamped from the injection plates. These test plates were stimulated at constant preload, possibly depending on the storage module, periodically with very small deformations and the active fixing force was measured as a function of the temperature and the stimulation frequency.

The additional pre-load used serves to keep the sample sufficiently taut at the point of negative strain amplitude.

The softening temperature Tr bb was determined as a characteristic temperature for the thermal state at E '= 3 MPa. The DMS measurements were carried out with the Seiko model DMS 210 of the company Seiko with 1HZ in the temperature range of -150 ° C to 200 ° C with a heating rate of 2 ° C / min.

Exposure to the weather of the samples The exposure to the weather of the test samples was carried out in a weathering device Cl 4,000 OM for 504 hours. The test cycle was 102 minutes of light and 18 minutes of light and rain at a standard darkening temperature of 65 ° C. The irradiation power amounted to 0.35 W / m2 at 340 nm and 50% relative humidity to the air. These conditions essentially corresponded to those of ISO 4892. In the test samples subjected to weathering, both the E 'module (DMS) measurements and the yellowness determinations were carried out.

Determination of yellowness The determination of yellowing was carried out in the test samples with the Minolta Chroma Meter CR-100 device. The determination of yellowing basically follows DIN 6167.

The device is calibrated in principle for each set of measurements. After the measuring flash has been triggered, the display should show the value indicated on the white contrast plate on the back.

The yellowing reference of the contrast plate amounts to 3.75.

The yellowing (Y) is calculated with the following measure: v. (2.45 __- i, i49) and 149 * 100 The yellowing (Y) can be calculated with the previous formula.

For the yellowing measurement, place the test sample on the white reference ceramic plate so that it overlaps the middle zones. Finally, the measurement flash fires. The values of x and y are measured, and the yellowness (Y) is calculated with the previous formula.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following:

Claims (23)

R E I V I N D I C A C I O N S

1. Thermoplastic polyurethane with yellowing < 20, preferably < 15 after a weather exposure of 504 hours according to IS04892 and with a softening temperature (measured by dynamic-mechanical analysis (DMS) in traction mode) Treb (with E '= 3 Mpa) > 100 ° C for thermoplastic polyurethanes with a hardness of 75 to 84 Shore A and with a softening temperature (measured by means of dynamic-mechanical analysis (DMS) in Treb traction mode (with E '= 3 Mpa) > 130 ° C for thermoplastic polyurethanes with a hardness of 85 to 98 Shore A, before and after 504 hours of exposure to the weather according to IS04892.

2. Thermoplastic polyurethanes according to claim 1, characterized in that they are obtained from: A) from 100 to 60% by moles of hexamethylene diisocyanate (HDI) and 0 to 40% by moles of another aliphatic diisocyanate B) polyol ester with an average molecular weight of between 600 and 5,000 g / mol C) chain extender with a mass average molecular weight of 60 to 500 g / mol D) UV stabilizers in an amount of 0.4 to 0.9% by weight, based on A) + B) + C) E) catalysts, where appropriate and F) adjuvants and conventional additives, where appropriate, in which the ratio of equivalents of diisocyanate A) to polyol B) is between 1.5: 1.0 and 10.0: 1.0 and in which the NCO index ( formed by the quotient of the equivalent ratios of the isocyanate groups and the sum of the hydroxyl groups of the polyols and chain extenders multiplied by 100) is from 95 to 105.

3. Thermoplastic polyurethanes according to claim 1, characterized in that they are obtained from: A) from 100 to 60% by moles of hexamethylene diisocyanate (HDI) and 0 to 40% by moles of another aliphatic diisocyanate B) polyether ether with an average molecular weight of between 600 and 5,000 g / mol C) chain extender with a mass molecular weight of 60 to 500 g / mol D) UV stabilizers in an amount of 0.4 to 0.9% by weight, based on A) + B) + C) E) catalysts, where appropriate and F) adjuvants and conventional additives, where appropriate in which the ratio of equivalents of diisocyanate A) to polyol B) is between 1.5: 1.0 and 10.0: 1.0 and in which the NCO index (formed by the quotient of the ratios of equivalents of the isocyanate groups and the sum of the hydroxyl groups of the polyols and chain extenders multiplied by 100) is from 95 to 105.

4. Thermoplastic polyurethanes according to claim 1, characterized in that they can be obtained from: A) from 100 to 60% by moles of hexamethylene diisocyanate (HDI) and 0 to 40% by moles of another aliphatic diisocyanate B) polyether / polyester mixture with an average molecular weight of between 600 and 5,000 g / mol C) chain with an average molecular weight of 60 to 500 g / mol D) UV stabilizers in an amount of 0.4 to 0.9% by weight, based on A) + B) + C) E) catalysts, where appropriate and F) conventional adjuvants and additives, where appropriate in which the ratio of equivalents of diisocyanate A) to polyol B) is between 1.5: 1.0 and 10.0: 1.0 and in which the NCO index (formed by the quotient of the ratios of equivalents of the isocyanate groups and the sum of the hydroxyl groups of the polyols and chain extenders multiplied by 100) is from 95 to 105.

5. Thermoplastic polyurethanes according to claim 1, characterized in that they are obtained from: A) from 100 to 60 mol% hexamethylene diisocyanate (HDI) and from 0 to 40 mol% of another aliphatic diisocyanate B) polyol ether / polydiol carbonate mixture with an average molecular weight of between 600 and 5,000 g / mol C) chain extender with an average molecular weight of 60 to 500 g / mol D) UV stabilizers in an amount of 0.4 to 0.9% by weight, based on A) + B) + C9 E) catalysts, in your case and F) conventional adjuvants and additives, where appropriate in which the ratio of equivalents of diisocyanate A) to polyol B) is between 1.5: 1.0 and 10.0: 1.0 and in which the NCO index (formed by the quotient of the ratios of equivalents of the isocyanate groups and the sum of the hydroxyl groups of the polyols and chain extenders multiplied by 100) is from 95 to 105.

6. Thermoplastic polyurethanes according to claim 1, characterized in that they can be obtained from: A) from 95 to 60 mol% hexamethylene diisocyanate (HDI), preferably from 90 to 60 mol% and from 5 to 40 mol% of another aliphatic diisocyanate, preferably from 10 to 40 mol% B) polyol ether mixture / polydiolcarbonate with an average molecular weight of between 600 and 5,000 g / mol C) chain extender with an average molecular weight of 60 to 500 g / mol D) UV stabilizers in an amount of 0.4 to 0.9% by weight, based on A) + B) + C) E) catalysts, where appropriate F) adjuvants and conventional additives, where appropriate in which the ratio of equivalents of diisocyanate A) to polyol B) is between 1.5: 1.0 and 10.0: 1.0 and in which the NCO index (formed by the quotient of the ratios of equivalents of the isocyanate groups and the sum of the hydroxyl groups of the polyols and chain extenders multiplied by 100) is from 95 to 105.

7. Thermoplastic polyurethanes according to claim 1, characterized in that they are obtained from: A) from 95 to 60 mol% hexamethylene diisocyanate (HDI), preferably from 90 to 60 mol% and from 5 to 40 mol% of another aliphatic diisocyanate, preferably from 10 to 40 mol% B) polydiol carbonate with a mass molecular weight of between 600 and 5,000 g / mol C) chain extender with an average molecular weight of 60 to 500 g / mol D) UV stabilizers in an amount of 0.4 to 0.9% by weight, based on A) + B) + C) E) catalysts, where appropriate F) adjuvants and conventional additives, where appropriate in which the ratio of equivalents of diisocyanate A) to polyol B) is between 1.5: 1.0 and 10.0: 1.0 and in which the NCO index (formed by the quotient of the ratios of equivalents of the isocyanate groups and the sum of the hydroxyl groups of the polyols and chain extenders multiplied by 100) is from 95 to 105.

8. Thermoplastic polyurethanes according to claim 1, characterized in that they are obtained from A) from 95 to 70% by moles of hexamethylene diisocyanate (HDI), and from 5 to 30% by moles of another aliphatic diisocyanate B) polyester, polyether polyol, a mixture of polyol ether and polyol ester, a mixture of polyether polyol ether and polydiol carbonate or a mixture of polyester polyol and polydiol carbonate with an average molecular weight between 600 and 5,000 g / mol C) chain extender with an average molecular weight of 60 to 500 g / mol D) stabilizers UV in an amount of 0.4 to 0.9% by weight, based on A) + B) + C) E) catalysts, where appropriate F) adjuvants and conventional additives, where appropriate in which the ratio of equivalents of diisocyanate A) to polyol B) is between 1.5: 1.0 and 10.0: 1.0 and in which the NCO index (formed by the quotient of the ratios of equivalents of the isocyanate groups and the sum of the hydroxyl groups of the polyols and chain extenders multiplied by 100) is from 95 to 105 and a test body obtained from the thermoplastic polyurethane shows only a poor patina formation ( entizamiento) on the surface after storage between 60 and 95 ° C for three weeks.

9. Thermoplastic polyurethanes according to claim 1, which are obtained from: A) from 100 to 60% by mole of hexamethylene diisocyanate (HDI) and from 0 to 40% by mole of another aliphatic diisocyanate B) polyester polyol, polyol ether, a mixture of polyether and polyester polyol, a mixture of polyether polyol ether and polydiol carbonate or a mixture of polyol ester and polydiol carbonate having a respective average molecular weight of between 500 and 5,000 g / mol C) of 80 to 100% by weight of 1,6-hexanediol and 0 to 20% by weight of chain extender with an average molecular weight of 60 to 500 g / mol D) UV stabilizers in an amount of 0.4 to 0.9% by weight, based on A) + B) + C ) E) catalysts, where appropriate and F) adjuvants and conventional additives, where appropriate in which the ratio of equivalents of diisocyanate A) to polyol B) is between 1.5: 1.0 and 10.0: 1.0 and in which the NCO index (formed by the quotient of the ratios of equivalents of the isocyanate groups and the sum of the hydroxyl groups of the polyols and chain extenders multiplied by 100) is from 95 to 105 and a test body obtained from the thermoplastic polyurethane shows only a poor patina formation ( entizamiento) on the surface after storage between 60 and 95 ° C for three weeks.

10. Process for the continuous production of the thermoplastic polyurethanes according to any of claims 1 to 9, characterized in that the polyol / mixture of polyols and the chain extender are mixed continuously and then intensively mixed with the diisocyanate / mixture of diisocyanates ( one-step process) and then the reaction is carried out in a delivery container (for example in an extruder) and the product obtained therefrom is granulated.

11. Process according to claim 10, characterized in that the reaction is carried out in the presence of a catalyst.

12. Process according to claims 10 or 11, characterized in that the temperatures of the mixture of polyol / (mixture of polyols) / chain extender and of the diisocyanate (mixture of diisocyanates) differ by not less than 20 ° C, preferably from 10 ° C .

13. Process according to claims 10 or 11, characterized in that the polyol / mixture of polyols and the chain extender are mixed continuously and then intensively mixed homogeneously with the diisocyanate / mixture of diisocyanates in a reactor in a time interval of at most 5 seconds, in which the temperatures of both mixtures before grouping in the reactor show a difference < 20 ° C.

14. Process according to claim 13, characterized in that the temperature of both mixtures before entering the reactor is between 60 and 150 ° C.

15. Process according to claim 13, characterized in that the reactor is a static mixer.

16. Procedure according to the claim 15, characterized in that the static mixer shows a length / diameter ratio in the range of 8: 1 to 16: 1.

17. Process for the continuous production of thermoplastic polyurethanes according to one or more of claims 1 to 9, characterized in that the polyol / mixture of polyols and the chain extender are continuously mixed, then reacted with hexamethylene diisocyanate, then mixed with the another aliphatic diisocyanate (second) and reacted, the reaction is terminated in a delivery container and the product is granulated if necessary.

18. Process for the continuous production of thermoplastic polyurethanes according to one or more of claims 1 to 9, characterized in that the polyol / mixture of polyols and the chain extender are mixed continuously, the mixture is reacted with the other aliphatic diisocyanate, then hexamethylene diisocyanate is added, the reaction is terminated in a delivery container and finally the product in its chaos is granulated.

19. Process for the continuous production of thermoplastic polyurethanes according to one or more of claims 1 to 9 according to the prepolymer process, characterized in that first the diisocyanate / mixture of diisocyanates is mixed with the polyol / polyol mixture and reacted until a prepolymer is obtained , this prepolymer is mixed in a second stage with the chain extender and reacted.

20. Use of the thermoplastic polyurethanes according to one of claims 1 to 9 or of the thermoplastic polyurethanes obtained according to the processes of claims 10 to 19 for the production of molding bodies.

21. Use according to claim 20 for obtaining extruded and injected castings.

22. Use of the thermoplastic polyurethanes according to one of claims 1 to 9 or of the thermoplastic polyurethanes obtained according to the processes of claims 10 to 19, as a sinterable powder for obtaining flat articles and hollow bodies.

23. Molding bodies, characterized in that they are obtained from a thermoplastic polyurethane according to one or more of claims 1 to 9 from a thermoplastic polyurethane obtained according to the processes of claims 10 to 19.