Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/83—Chemically modified polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/16—Nitrogen-containing compounds
  • C08K5/29—Compounds containing one or more carbon-to-nitrogen double bonds
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B11/00—Making preforms
  • B29B11/06—Making preforms by moulding the material
  • B29B11/10—Extrusion moulding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
  • B29C48/04—Particle-shaped
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
  • C08G18/72—Polyisocyanates or polyisothiocyanates
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
  • C08J5/18—Manufacture of films or sheets
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L75/00—Compositions of polyureas or polyurethanes; Compositions of derivatives of such polymers
  • C08L75/04—Polyurethanes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
  • B29C48/25—Component parts, details or accessories; Auxiliary operations
  • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
  • B29C48/919—Thermal treatment of the stream of extruded material, e.g. cooling using a bath, e.g. extruding into an open bath to coagulate or cool the material

Definitions

• the invention relates to processes for producing polyurethanes, in which the production is carried out in the presence of the inventive thermoplastic polyurethanes (i) comprising the isocyanates. Furthermore, the invention relates to processes for reacting thermoplastic polyurethanes with isocyanate, for example in an extruder, in which the inventive thermoplastic polyurethanes (i) comprising isocyanates are used as isocyanate. In addition, the invention relates to processes for injection molding thermoplastic polyurethane, in which thermoplastic polyurethane is injection molded together with the inventive thermoplastic polyurethane (i) comprising isocyanates.
• thermoplastic polyurethanes hereinafter referred to as TPUs for short, is generally known.
• TPUs are partially crystalline materials and belong to the class of thermoplastic elastomers.
• a characteristic of polyurethane elastomers is the segmented structure of the macromolecules. Owing to the differing cohesion energy densities of these segments, a phase separation into crystalline “hard” and amorphous “soft” regions occurs in the ideal case. The resulting two-phase structure determines the property profile of TPUs.
• Thermoplastic polyurethanes are plastics having a wide range of applications. Thus, TPUs are used, for example, in the automobile industry, e.g. in dashboard skins, in films, in cable sheathing, in the leisure industry, as deposition areas, as functional and design elements in sports shoes, as flexible component in rigid-flexible combinations and in many further applications.
• TPU can be improved by introducing crosslinking into the TPU, leading to the strength being increased, the heat resistance being increased, the tensile and compressive sets being reduced, the resistance to media of all types, resilience and creep behavior being improved.
• crosslinking methods are, inter alia, UV or electron beam crosslinking, crosslinking via siloxane groups and the formation of crosslinks by addition of isocyanates to the molten TPU.
• the reaction of a TPU, preferably in the molten state, with compounds bearing isocyanate groups is also referred to as prepolymer crosslinking and is generally known from U.S. Pat. No. 4,261,946, U.S. Pat. No. 4,347,338, DE-A 41 15 508, DE-A 4 412 329, EP-A 922 719, GB 2347933, U.S. Pat. No. 6,142,189, EP-A 1 158 011.
• the reaction of the TPU with the compounds having isocyanate groups also represents a difficult chemical task, since mixing of the molten TPU with diisocyanates can lead to a degradation of the molecular weight of the thermoplastic polyurethanes, while mixing with triisocyanates and polyisocyanates can cause an increase in the molecular weight as far as crosslinking of the thermoplastic polyurethanes in the extruder. In both cases, reliable processing of the polyurethane is made difficult or prevented. On the other hand, very pronounced crosslinking in the end product is sought.
• the present invention is distinguished from the prior art by, in particular, the substantially simplified handling of the isocyanates. While liquid isocyanates have to be handled in most of the documents cited above, according to the present invention it is possible to add solids in the form of the thermoplastic polyurethanes (i) comprising the isocyanates. The addition of a solid is of particular importance for injection molding. In addition, the adhesion of a thermoplastic polyurethane to other thermoplastic polymers in, in particular, 2-component injection molding has been able to be substantially improved by use of the concentrate (i), either alone or together with further thermoplastic polyurethane, presumably as a result of the free isocyanate groups.
• the solid concentrates (i) offer the advantage that the volatility of the isocyanates is significantly reduced. It has surprisingly been found that a TPU comprising 50% by weight of a prepolymer based on MDI and having an NCO content of 23% and a viscosity of 650 mPas determined in accordance with DIN 53018 was, firstly, free-flowing and, secondly, no volatile MDI could be detected.
• the isocyanates are stable in the inventive TPUs (i), i.e. they barely react or do not react at all and are therefore, contrary to expectations, sufficiently storage-stable.
• thermoplastic polyurethanes (i) comprising the isocyanates can thus be used and processed like concentrates. While in the prior art the addition of the isocyanate to the thermoplastic polyurethane is carried out immediately before processing to the end product and crosslinking, according to the invention it is possible to produce a stable concentrate (i) which can be processed only at a significantly later point in time together with further thermoplastic polyurethane to form the end product. A distinction is therefore made in the present text between the concentrates of the invention, i.e. the thermoplastic polyurethane (i) comprising the isocyanate, and the “normal” thermoplastic polyurethanes which do not comprise isocyanates in the amounts according to the invention. The concentrates are denoted by (i) in the present text.
• the isocyanates are present as a solution in the TPU, in particular in the soft phase of the thermoplastic polyurethane. Reaction of the isocyanate with the TPU and thus degradation or crosslinking of the TPU can be avoided, in particular, by a sufficiently low temperature being selected during incorporation.
• the molecular weight of the TPU usually does not change or changes only very slightly during the incorporation according to the invention of the isocyanates.
• the thermoplastic polyurethane is molten during the incorporation of the isocyanate in order to be able to reach a very high concentration of isocyanates in the TPU very quickly.
• the inventive thermoplastic polyurethane (i) comprising isocyanate is preferably stored at a temperature below 40° C. until it is processed.
• thermoplastic polyurethanes (i) comprising the isocyanates particularly preferably have an NCO content of greater than 5%, preferably greater than 8%, particularly preferably from 10% to 40%.
• the NCO content is determined as the sum of isocyanate and allophanate.
• the sample is for this purpose dissolved in dimethylformamide comprising the amine and maintained at 80° C. for 4 hours. The unreacted excess of amine is backtitrated with acid.
• a sample to be tested for isocyanate content is weighed out.
• the amount weighed out depends on the expected content of isocyanate groups and is weighed to a precision of ⁇ 0.001 g.
• the analysis is carried out as a duplicate determination.
• the samples are then cooled to room temperature and can then be titrated.
• indicator solution bromophenol blue, 1% in DMF
• 0.1 N hydrochloric acid prepared by making up the content of an ampoule of Titrisol 0.1 mol/l hydrochloric acid to 1 l with 1-butanol
• Dosimat 665 Microhm Dosimat 665 with 5 ml burette attachment
• the mean of the duplicate determination is the NCO content of the TPU sample (i).
• isocyanates in the thermoplastic polyurethane (i) of the invention generally known isocyanates, for example aliphatic, cycloaliphatic and/or aromatic isocyanates generally having 2 isocyanate groups, can be present.
• Isocyanates of higher functionality e.g. polymeric MDI or modified isocyanates, for example isocyanates which comprise biuret groups and have from 2 to 10 isocyanate groups, isocyanurates which preferably have from 2 to 8, particularly preferably 3, isocyanate groups, and/or prepolymers which have from 2 to 10 isocyanate groups, i.e. isocyanates, and are obtainable by reacting isocyanates with compounds which are reactive toward isocyanates, generally alcohols, are also possible.
• isocyanates examples are thus trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene and/or octamethylene diisocyanate, 2-methylpentamethylene 1,5-diisocyanate, 2-ethylbutylene 1,4-diisocyanate, pentamethylene 1,5-diisocyanate, butylene 1,4-diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 1,4- and/or 1,3-bis(isocyanatomethyl)cyclohexane (HXDI), cyclohexane 1,4-diisocyanate, 1-methylcycloxane 2,4- and/or 2,6-diisocyanate and/or dicyclohexylmethane 4,4′-, 2,4′- and 2,2′-diisocyanate, di
• MDI diphenylmethane 2,2′-, 2,4′- and/or 4,4′-diisocyanate
• MDI carbodiimide-modified diphenylmethane 2,2′-, 2,4′- and/or 4,4′-diisocyanate
• MDI diphenylmethane 2,2′-, 2,4′- and/or 4,4′-diisocyanate
• triisocyanates or polyisocyanates in particular biurets or isocyanurates of the isocyanates mentioned, in particular an isocyanurate having an NCO content of from 20% to 25% and a viscosity at 23° C.
• mixtures (ii) comprising (iia) compounds which have at least three, preferably three, isocyanate groups and are based on aliphatic isocyanates, preferably hexamethylene diisocyanate (HDI) and/or 1-isocyanato-3,3,5-trimethyl-5-isocyanato-methylcyclohexane (isophorone diisocyanate, IPDI), particularly preferably hexamethylene diisocyanate (HDI), and (iib) compounds which have two isocyanate groups and are based on aromatic isocyanates, preferably diphenylmethane 2,2′-, 2,4′- and/or 4,4′-diisocyanate (MDI), particularly preferably diphenylmethane 4,4′-diisocyanate.
• MDI diphenylmethane 2,2′-, 2,4′- and/or 4,4′-diisocyanate
• an isocyanurate having three isocyanate groups preference is given to using an isocyanurate having three isocyanate groups, preferably an isocyanurate based on HDI, i.e. a trimerized HDI in which three HDI units form an isocyanurate structure and three free isocyanate groups are present.
• MDI diphenylmethane 2,2′-, 2,4′- and/or 4,4′-diisocyanate
• MDI diphenylmethane 2,2′-, 2,4′- and/or 4,4′-diisocyanate
• MDI diphenylmethane 2,2′-, 2,4′- and/or 4,4′-diisocyanate
• alkanediol preferably dipropylene glycol, having a molecular weight of from 60 g/mol to 400 g/mol
• polyether diol preferably polypropylene glycol ether, having a molecular weight of from 500 g/mol to 4000 g/mol as (iib).
• (iia) and (iib) are preferably used in a weight ratio of (iia):(iib) of from 1:1 to 1:10, preferably from 1:3 to 1:4.
• isocyanates are diphenylmethane 2,2′-, 2,4′- and/or 4,4′-diisocyanate (MDI), a carbodiimide-modified diphenylmethane 2,2′-, 2,4′- and/or 4,4′-diisocyanate (MDI), a prepolymer based on diphenylmethane 2,2′-, 2,4′- and/or 4,4′-diisocyanate (MDI), preferably a prepolymer having an NGO content of from 20 to 25% and a viscosity at 25° C.
• MDI diphenylmethane 2,2′-, 2,4′- and/or 4,4′-diisocyanate
• MDI carbodiimide-modified diphenylmethane 2,2′-, 2,4′- and/or 4,4′-diisocyanate
• MDI a prepolymer based on diphenylmethane 2,2′-, 2,4
• isocyanates comprising biuret and/or isocyanurate groups, particularly preferably an isocyanurate having an NCO content of from 20% to 25% and a viscosity at 23° C. of from 2500 mPas and 4000 mPas determined in accordance with DIN EN ISO 3219, in particular one based on hexamethylene diisocyanate (HDI).
• isocyanates comprising biuret and/or isocyanurate groups, particularly preferably an isocyanurate having an NCO content of from 20% to 25% and a viscosity at 23° C. of from 2500 mPas and 4000 mPas determined in accordance with DIN EN ISO 3219, in particular one based on hexamethylene diisocyanate (HDI).
• HDI hexamethylene diisocyanate
• MDI carbodiimide-modified diphenylmethane 4,4′-diiso
• thermoplastic polyurethane (i) comprising the isocyanates
• thermoplastic polyurethanes e.g. ones based on aliphatic or aromatic starting substances.
• the thermoplastic polyurethanes into which the isocyanates are introduced and which subsequently represent the inventive thermoplastic polyurethanes (i) comprising the isocyanates can have a generally known hardness.
• Thermoplastic polyurethanes in the preferred hardness ranges for producing the inventive thermoplastic polyurethanes (i) comprising the isocyanates are optimized in respect of two aspects: firstly, the isocyanate is dissolved predominantly in the soft phase so that the TPU should be as soft as possible in order to dissolve a large amount of isocyanate in the TPU. Secondly, the TPU should be sufficiently free-flowing after the incorporation. This is achieved by the TPU being sufficiently hard for the hard phase to be able to crystallize sufficiently quickly after incorporation of the isocyanate.
• thermoplastic polyurethane (i) comprising the isocyanates is preferably in the form of pellets, preferably pellets having a preferred mean particle diameter of from 0.05 mm to 10 mm, preferably from 1 mm to 5 mm.
• thermoplastic polyurethane (i) comprising isocyanate
• the production of the inventive thermoplastic polyurethane (i) comprising isocyanate can be carried out by melting thermoplastic polyurethane and subsequently incorporating the isocyanate into thermoplastic polyurethane melt, preferably homogeneously.
• the resulting thermoplastic polyurethane melt (i) should preferably have a temperature in the range from 120° C. to 160° C. Particular preference is given to melting the thermoplastic polyurethane at a temperature of from 170° C. to 280° C., preferably from 170 to 240° C., and subsequently mixing the isocyanate at a temperature of from 20 to 80° C. into this melt so that the resulting mixture has a temperature of less than 160° C., preferably in the range from 120° C. to 160° C.
• Such processing at a target temperature of less than 160° C. offers the advantage that degradation of the thermoplastic polyurethane caused by the addition of diisocyanates or crosslinking of the thermoplastic polyurethane due to the introduction of triisocyanates or polyisocyanates can be avoided at this temperature.
• the isocyanate can preferably be incorporated into the thermoplastic polyurethane by means of an extruder, preferably by means of a twin-screw extruder.
• thermoplastic polyurethane (i) comprising isocyanate
• the product obtainable from the extruder i.e. the thermoplastic polyurethane (i) comprising isocyanate
• the strand obtained can subsequently be pelletized, for example, by means of generally known methods.
• the product obtainable from the extruder i.e. the TPU melt (i) comprising the isocyanate
• the TPU melt (i) can preferably be extruded through a multihole die directly from the extruder into a water bath and subsequently cut up by means of a rotating knife (underwater pelletization).
• the TPU melt (i) is preferably extruded in the water, preferably through a multihole die, and cut up by means of a rotating knife, preferably in the water.
• the invention also provides processes for producing polyurethanes, for example crosslinked or thermoplastic, compact or cellular, rigid, semirigid or flexible polyurethanes which may, if appropriate, comprise urea and/or isocyanurate groups, with the production being carried out in the presence of the thermoplastic polyurethanes (i) of the invention.
• the thermoplastic polyurethanes (i) comprising the isocyanates are used as isocyanate concentrate, effectively as sole or additional isocyanate component, if appropriate in addition to further customary isocyanates.
• polyurethanes for example crosslinked or thermo-plastic, compact or cellular, rigid, semirigid or flexible polyurethanes which may, if appropriate, comprise urea and/or isocyanurate groups
• Processes for producing polyurethanes are usually carried out by reacting (a) isocyanates with (b) compounds which are reactive toward isocyanates, preferably by reacting (a) isocyanates with (b) compounds having hydrogen atoms which are reactive toward isocyanate groups, preferably in the presence of catalysts (d), (f) physical and/or chemical blowing agents and, if appropriate, (e) additives, and are generally known.
• the process of the invention is distinguished from these known processes by, as indicated, the inventive thermoplastic polyurethanes (i) comprising the isocyanates being used as isocyanate (a).
• the invention also provides, in particular, processes for reacting thermoplastic polyurethanes with isocyanate, with the inventive thermoplastic polyurethane (i) comprising isocyanates being used as isocyanate.
• thermoplastic polyurethanes two different thermoplastic polyurethanes are thus used: firstly, the thermoplastic polyurethane which is usually in pelletized or molten form and is to be crosslinked by the addition of isocyanates and, secondly, the inventive thermoplastic polyurethane (i) comprising the isocyanates, i.e. the isocyanate concentrate, which is added to the TPU to be crosslinked.
• thermoplastic polyurethane (i) comprising the isocyanates
• these isocyanate groups form crosslinks in the form of, for example, urethane, allophanate, uretdione and/or isocyanurate structures and possibly urea and biuret bonds during and/or after mixing of the TPU with the thermoplastic polyurethane (i) in the cold or preferably hot, particularly preferably molten, state of the components, leading to improved properties of the polyisocyanate polyaddition products.
• crosslinks can, if appropriate, be promoted by addition of catalysts which are generally known for this purpose, for example alkali metal acetates and/or formates.
• catalysts which are generally known for this purpose, for example alkali metal acetates and/or formates.
• crosslinking by free isocyanate-reactive groups, e.g. hydroxyl groups of primary or secondary amino groups, in particular hydroxyl groups, of the linear TPU polymer also occurs.
• These reactive groups can be present originally in the TPU granules, but they are also formed in the TPU melt in the extruder, e.g. by thermal dissociation of the polymer strand under processing conditions or during storage or heating of the isocyanate-rich material.
• thermoplastic polyurethane (i) comprising isocyanates per 100 parts by weight of thermoplastic polyurethane.
• the addition of even small proportions of the concentrate can be useful to compensate for fluctuations in the composition of TPU batches by addition of small amounts of isocyanate.
• the concentrate (i) is preferably added to the thermoplastic polyurethane by introducing preferably pelletized thermoplastic polyurethane, i.e. the thermoplastic polyurethane into which isocyanate groups are to be introduced by means of the concentrate (i), together with the preferably pelletized thermoplastic polyurethane (i), i.e. the concentrate comprising the isocyanate, into an extruder and melting and mixing them, preferably in the molten state.
• thermoplastic polyurethane into the extruder, melt it and subsequently add concentrate (i), preferably as pellets, to the melt.
• the pelletized thermoplastic polyurethane can be introduced together with the thermoplastic polyurethane (i) into the extruder, preferably by means of a feeding aid.
• the extruder preferably has a barrier screw.
• thermoplastic polyurethane (i) is particularly preferably introduced together with thermoplastic polyurethanes through the feeding aid into the extruder or the injection-molding apparatus, i.e. the same feeding aid is used for the TPU and the thermoplastic polyurethane (i).
• the extruder can be a generally known extruder as is generally known, for example, for the extrusion of TPU, e.g. a single- or preferably twin-screw extruder, particularly preferably a single-screw extruder with feeding aid, in particular a grooved feeding aid.
• TPU thermoplastic polyurethane
• Feeding aids for extruders are generally known to those skilled in the art of extrusion and have been described widely.
• the feeding aid is preferably a grooved feed zone.
• Grooved feeding aids, grooved-barrel extruders or extruders having a grooved feed zone are generally known to those skilled in the art of extruder technology and have been described widely, for example in “Der Extruder im Extrusionsproze ⁇ —Grundlage für provide und Boat fixtures”, VDI-Verlag GmbH, Düsseldorf, 1989, ISBN 3-18-234141-3, pages 13 to 27.
• a characteristic of a grooved feed zone is the presence of longitudinal grooves in the barrel wall which are usually essentially parallel to the longitudinal extension of the screw in the feed zone of the extruder and usually taper conically in the transport direction to the end of the feed zone.
• the grooves preferably have a depth which is in the range from 10% to 90% of the mean particle diameter of the TPU, i.e. the depth of the grooves is significantly smaller than the mean particle diameter of the pelletized TPU.
• the grooves particularly preferably have a depth of from 1 mm to 8 mm, preferably from 2 mm to 5 mm.
• the grooved feed zone preferably has a length in the range from 2 times to 4 times the screw diameter.
• the grooved feed zone preferably has from 4 to 32 grooves, particularly preferably from 4 to 16 grooves, which preferably run parallel or helically, preferably parallel, relative to the longitudinal axis of the extruder.
• screws it is possible to use generally known screws, e.g. 3- or 5-zone screws. Particular advantages are obtained in the present process when an extruder which has a barrier screw is used.
• Barrier screws are generally known in extrusion, e.g. from “Der Extruder im Extrusionsproze ⁇ —Grundlage für provide und Boatigi”, VDI-Verlag GmbH, Düsseldorf, 1989, ISBN 3-18-234141-3, pages 107 to 125, pages 139 to 143.
• the temperature of the melt in the extruder or in the injection-molding apparatus, preferably the extruder, is usually from 150° C. to 240° C., preferably from 180° C. to 230° C.
• the residence time of the TPU in the extruder is preferably from 120 s to 600 s.
• the present invention provides processes for injection molding thermoplastic polyurethane, in which thermoplastic polyurethane to which isocyanate is to be added by means of the concentrate (i) and which is usually to be crosslinked by means of these isocyanate groups after injection molding is injection molded together with the inventive thermoplastic polyurethane (i) comprising isocyanates.
• the concentrate of the invention i.e. the thermoplastic polyurethane (i) comprising the isocyanate
• the solid concentrates (i) enable liquid isocyanates to be dispensed with. Nevertheless, a high content of free isocyanate groups can be introduced into the injection-molded shaped body by means of the concentrate (i). This content of free isocyanate groups can subsequently be utilized as desired for crosslinking.
• thermoplastic polyurethane in which thermoplastic polyurethane is injection molded as one component in two-component injection molding together with thermoplastic polyurethane (i) comprising isocyanates and is preferably injection molded onto a further thermoplastic polymer, preferably in an adhering fashion.
• thermoplastic polymers The injection molding of thermoplastic polymers is generally known and has been widely described, in particular for thermoplastic polyurethane, too.
• 2-C two-component injection molding
• the temperature in the injection molding of thermoplastic polyurethane is preferably from 140° C. to 250° C., particularly preferably from 160° C. to 230° C.
• TPUs are preferably processed under mild conditions. The temperatures can be adapted depending on the hardness.
• the circumferential velocity during plasticization is preferably less than or equal to 0.2 m/s, and the back pressure is preferably from 30 to 200 bar.
• the injection velocity is preferably small in order to keep the shear stress low.
• the cooling time is preferably chosen so as to be sufficiently long, with the hold pressure preferably being from 30 to 80% of the injection pressure.
• the molds are preferably heated to from 30° C. to 70° C.
• the gate is preferably chosen at the thickest part of the component. In the case of wide-area overinjections, an injection point cascade can be used.
• thermoplastic polymers preferably rigid thermoplastic polymers
• further thermoplastic polymers for example polyamides, polyesters, polycarbonates, ABS, together with the TPU. Preference is given to firstly producing the molding from a rigid thermoplastic polymer by means of injection molding and subsequently injection molding the thermoplastic polyurethane comprising the concentrate (i) onto this.
• thermoplastic polyurethane adheres particularly well to further generally known thermoplastic polymers which are used together with the thermoplastic polyurethane in 2-component injection molding.
• the process product according to the invention i.e. the TPU comprising the thermoplastic polyurethane (i) with the isocyanate
• the processing temperature in production of the films, moldings or fibers is preferably from 150° C. to 230° C. particularly preferably from 180° C. to 220° C.
• Processing of the mixture to produce the desired films, moldings and/or fibers is preferably carried out immediately after or during the mixing of the TPU with the thermoplastic polyurethane (i), since thermoplastic processing of polyisocyanate polyaddition products to produce films, moldings or fibers is preferably carried out before and/or during formation of the crosslinks.
• the process products from extrusion, injection molding or melt spinning, for example the moldings, films or fibers, can subsequently be heat treated/stored at a temperature of, for example, from 20° C. to 100° C. for a period of usually at least 2 hours, preferably from 12 to 48 hours, to form allophanate, uretdione and/or isocyanurate crosslinks, possibly also urea bonds and biurets by hydrolysis, by means of the isocyanate groups present in excess in the polyisocyanate polyaddition products.
• a temperature of, for example, from 20° C. to 100° C. for a period of usually at least 2 hours, preferably from 12 to 48 hours to form allophanate, uretdione and/or isocyanurate crosslinks, possibly also urea bonds and biurets by hydrolysis, by means of the isocyanate groups present in excess in the polyisocyanate polyaddition products.
• thermoplastic polyurethane is extruded together with the thermoplastic polyurethane (i) comprising isocyanates.
• thermoplastic polyurethane i
• isocyanates The production of films based on TPU is generally known and has been described widely.
• skis which have these films according to the invention, in particular as supports for the ski decor.
• These preferably transparent films are printed on the reverse side and subsequently adhesively bonded to the ski support.
• the advantage of the TPU film is the particularly good abrasion resistance, cold flexibility and high transparency. A ski produced in this way no longer has to be after-treated.
• thermosublimation printing has hitherto not been possible for TPU films.
• the sublimation dye runs further into the matrix after printing and the printing becomes blurred very quickly.
• TPU concentrate (i) comprising isocyanate to the TPU and thus the incorporation of isocyanate groups into the TPU film enables the migration of the printing ink in the film and thus a blurred printed image to be prevented.
• This advantage i.e. the effective prevention of the migration of the dye, is particularly useful when using amine dyes.
• binders for dye are: starch, cellulose, agar, porous materials, hydrolyzed PVC-PVA or PVA (EP0531579B1 and U.S. Pat. No. 6,063,842).
• Possible binders on paper/carrier film are, for example, ZnO, CaCO 3 , polyvinyl alcohol, cellulose, metal salts, metal sulfides, TiO 2 or SiO 2 , with this also serving as white pigment for improving the contrast and also as filler to make the material opaque.
• the present invention therefore also provides skis which preferably have a transparent, printed, preferably by means of amine dyes, preferably by means of thermosublimation printing, film based on a thermoplastic polyurethane comprising isocyanate, preferably a thermoplastic polyurethane (i) comprising isocyanate, on at least part of their visible surface.
• TPUs are generally known and have been described widely.
• thermoplastic polyurethanes can be produced by reacting (a) isocyanates with (b) compounds which are reactive toward isocyanates and have a molecular weight of from 500 to 10 000 and, if appropriate, (c) chain extenders having a molecular weight of from 50 to 499, if appropriate in the presence of (d) catalysts and/or (e) customary auxiliaries.
• auxiliaries and additives may be found in the specialist literature, e.g. Plastics Additive Handbook, 5th edition, H. Zweifel, ed., Hanser Publishers, Kunststoff, 2001. All molecular weights mentioned in the present text have the units [g/mol].
• the molar ratios of the formative components (b) and (c) can be varied within a relatively wide range.
• the reaction can be carried out at customary indexes, preferably at an index of from 950 to 1050, particularly preferably at an index in the range from 970 to 1010, in particular from 980 to 995.
• the index is defined as the molar ratio of the total isocyanate groups of the component (a) used in the reaction to the isocyanate-reactive groups, i.e. the active hydrogens, of the components (b) and (c).
• an index of 1000 there is one active hydrogen atom, i.e. one isocyanate-reactive function, of the components (b) and (c) per isocyanate group of the component (a).
• indexes above 1000 there are more isocyanate groups than OH groups present.
• the production of the TPUs can be carried out by known methods either continuously, for example by means of reaction extruders or the belt process by the one-shot or the prepolymer process, or discontinuously by the known prepolymer process.
• the components (a), (b) and, if appropriate, (c), (d) and/or (e) which are reacted can be mixed with one another either in succession or simultaneously, with the reaction commencing immediately.
• the formative components (a), (b) and, if appropriate, (c), (d) and/or (e) are introduced individually or as a mixture into the extruder, reacted at, for example, temperatures of from 100° C. to 280° C., preferably from 140° C. to 250° C., and the TPU obtained is extruded, cooled and pelletized.
• TPUs as described in WO 03/014179 are particularly suitable both for producing the concentrates (i) and for mixing with the concentrate (i).
• the following information up to the examples is based on this particularly preferred TPU.
• TPUs are preferably obtainable by reacting (a) isocyanates with (b1) polyester diols having a melting point of greater than 150° C., (b2) polyether diols and/or polyester diols in each case having a melting point of less than 150° C. and a molecular weight of from 501 to 8000 g/mol and, if appropriate, (c) diols having a molecular weight of from 62 g/mol to 500 g/mol.
• thermoplastic polyurethanes in which the molar ratio of the diols (c) having a molecular weight of from 62 g/mol to 500 g/mol to the component (b2) is less than 0.2, particularly preferably from 0.1 to 0.01.
• thermoplastic polyurethanes in which the polyester diols (b1), which preferably have a molecular weight of from 1000 g/mol to 5000 g/mol, comprise the following structural unit (I):
• R1, R2, R3 and X have the following meanings:
• melting point refers to the maximum of the melting peak of a heating curve measured using a commercial DSC instrument (e.g. DSC 7/from Perkin-Elmer).
• the molecular weights reported in the present text are the number average molecular weights in [g/mol].
• thermoplastic polyurethanes can preferably be prepared by reacting a, preferably high molecular weight, preferably partially crystalline, thermoplastic polyester with a diol (c) in a first step (I) and subsequently, in a further reaction (II), reacting the reaction product from (I) comprising (b1) polyester diol having a melting point of greater than 150° C. and, if appropriate, (c) diol together with (b2) polyether diols and/or polyester diols in each case having a melting point of less than 150° C.
• the molar ratio of the diols (c) having a molecular weight of from 62 g/mol to 500 g/mol to the component (b2) in the reaction (II) is preferably less than 0.2, preferably from 0.1 to 0.01.
• step (I) While the hard phases are made available for the end product in step (I) by means of the polyester used in step (I), the use of the component (b2) in step (II) results in formation of the soft phases.
• the preferred technical teaching is that polyesters having a pronounced, readily crystallizing hard phase structure are melted, preferably in a reaction extruder, and firstly degraded by reaction with a low molecular weight diol to form shorter polyesters having free hydroxyl end groups.
• the original high crystallization tendency of the polyester is retained and can subsequently be utilized in a rapidly occurring reaction to obtain TPUs having the advantageous properties such as high tensile strength, low abrasion values and, because of the high and narrow melting range, high heat distortion resistances and low compression sets.
• thermoplastic polyesters are degraded in a short reaction time by reaction with low molecular weight diols (c) under suitable conditions to give rapidly crystallizing polyester diols (b1) which in turn are then incorporated into high molecular weight polymer chains together with other polyester diols and/or polyether diols and diisocyanates.
• thermoplastic polyester used i.e. before the reaction (I) with the diol (c), preferably has a molecular weight of from 1 5 000 g/mol to 40 000 g/mol and preferably has a melting point of greater than 160° C., particularly preferably from 170° C. to 260° C.
• polyester which is reacted in step (I), preferably in the molten state, particularly preferably at a temperature of from 230° C. to 280° C. for a time of preferably from 0.1 min to 4 min, particularly preferably from 0.3 min to 1 min, with the diol(s) (c), it is possible to use generally known, preferably high molecular weight, preferably partially crystalline, thermoplastic polyesters, for example in pelletized form. Suitable polyesters are based, for example,.
• aliphatic, cycloaliphatic, araliphatic and/or aromatic dicarboxylic acids for example lactic acid and/or terephthalic acid
• aliphatic, cycloaliphatic, araliphatic and/or aromatic dialcohols for example 1,2-ethanediol, 1,4-butanediol and/or 1,6-hexanediol.
• polyesters are: poly-L-lactic acid and/or polyalkylene terephthalate, for example polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, in particular polybutylene terephthalate.
• thermoplastic polyester is preferably melted at a temperature of from 180° C. to 270° C.
• reaction (I) with the diol (c) is preferably carried out at a temperature of from 230° C. to 280° C., preferably from 240° C. to 280° C.
• diols having a molecular weight of from 62 to 500 g/mol, for example the diols mentioned at a later point, e.g. ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6
• the weight ratio of the thermoplastic polyester to the diol (c) in step (I) is usually from 100:1.0 to 100.10, preferably from 100:1.5 to 100:8.0.
• the reaction of the thermoplastic polyester with the diol (c) in reaction step (I) is preferably carried out in the presence of customary catalysts, for example those which are described at a later point. Preference is given to using catalysts based on metals for this reaction.
• the reaction in step (I) is preferably carried out in the presence of from 0.1 to 2% by weight of catalysts, based on the weight of the diol (c).
• the reaction in the presence of such catalysts is advantageous in order to enable the reaction to be carried out in the short residence time available in the reactor, for example a reaction extruder.
• Possible catalysts for this reaction step (I) are, for example: tetrabutyl orthotitanate and/or tin(II) dioctoate, preferably tin dioctoate.
• the polyester diol (b1) as reaction product from (I) preferably has a molecular weight of from 1000 g/mol to 5000 g/mol.
• the melting point of the polyester diol as reaction product from (I) is preferably from 150° C. to 260° C., in particular from 165° C. to 245° C., i.e. the reaction product of the thermoplastic polyester with the diol (c) in step (I) comprises compounds which have the melting point mentioned and are used in the subsequent step (II).
• the polymer chain of the polyester is cleaved by transesterification by means of the diol (c).
• the reaction product of the thermoplastic polyester therefore has free hydroxyl end groups and is preferably processed further in the further step (II) to give the actual product, viz. the TPU.
• the reaction of the reaction product from step (I) in step (II) is preferably carried out by addition of a a) isocyanate (a) and (b2) polyether diols and/or polyester diols in each case having a melting point of less than 150° C. and a molecular weight of from 501 to 8000 g/mol and, if appropriate, further diols (c) having a molecular weight of from 62 to 500, (d) catalysts and/or (e) auxiliaries to the reaction product from (I).
• the reaction of the reaction product with the isocyanate occurs via the hydroxyl end groups formed in step (I).
• the reaction in step (II) is preferably carried out at a temperature of from 190° C.
• step (I) preferably from 0.5 to 5 min, particularly preferably from 0.5 to 2 min, preferably in a reaction extruder, particularly preferably in the same reaction extruder in which step (I) has also been carried out.
• the reaction of step (I) can be carried out in the first barrel section of a customary reaction extruder and the corresponding reaction of step (II) can be carried out at a later point, i.e. later barrel sections, after addition of the components (a) and (b2).
• the first 30-50% of the length of the reaction extruder can be used for step (I) and the remaining 50-70% can be used for step (II).
• the reaction in step (II) is preferably carried out at an excess of isocyanate groups over the groups which are reactive toward isocyanates.
• the ratio of isocyanate groups to hydroxyl groups in the reaction (II) is preferably from 1:1 to 1.2:1, particularly preferably from 1.02:1 to 1.2:1.
• reaction extruder a generally known reaction extruder.
• reaction extruders are described, for example, in the company brochure of Werner & Pfleiderer or in DE-A 2 302 564.
• the preferred process is preferably carried out by metering at least one thermoplastic polyester; e.g. polybutylene terephthalate, into the first barrel section of a reaction extruder and melting it at temperatures of preferably from 180° C. to 270° C., preferably from 240° C. to 270° C., adding a diol (c), e.g. butanediol, and preferably a transesterification catalyst in a subsequent barrel section, degrading the polyester by reaction with the diol (c) at temperatures of from 240° C. to 280° C.
• a diol (c) e.g. butanediol
• transesterification catalyst e.g. butanediol
• polyester oligomers having hydroxyl end groups and molecular weights of from 1000 to 5000 g/mol, adding isocyanate (a) and (b2) compounds which are reactive toward isocyanates and have a molecular weight of from 501 to 8000 g/mol and, if appropriate, (c) diols having a molecular weight of from 62 to 500, (d) catalysts and/or (e) auxiliaries in a subsequent barrel section and subsequently carrying out the formation of the preferred thermoplastic polyurethanes at temperatures of from 190° C. to 250° C.
• step (II) preference is given to feeding in no diols (c) having a molecular weight of from 62 to 500 apart from the diols (c) present in the reaction product from (i).
• the reaction extruder preferably has neutral and/or backward-transporting kneading blocks and back-transporting elements, preferably screw mixing elements, toothed disks and/or toothed mixing elements in combination with back-transporting elements, in the region in which the thermoplastic polyester is melted and also in the region in which the thermoplastic polyester is reacted with the diol.
• the clear melt is usually conveyed by means of a gear pump to underwater pelletization and pelletized.
• thermoplastic polyurethanes give optically clear, single-phase melts which solidify rapidly and, owing to the partial crystalline polyester hard phase, form slightly opaque to opaque white moldings.
• the rapid solidification behavior is an important advantage compared to known formulations and production processes for thermoplastic polyurethanes.
• the rapid solidification behavior is so pronounced that even products having hardnesses of from 50 to 60 Shore A can be processed by injection molding with cycle times of less than 35 s.
• no problems typical of TPUs e.g. conglutination or blocking of the films or film bubbles, occur.
• thermoplastic polyester in the end product i.e. the thermoplastic polyurethane
• the proportion of thermoplastic polyester in the end product is preferably from 5 to 75% by weight.
• the preferred thermoplastic polyurethanes are particularly preferably products of the reaction of a mixture comprising form 10 to 70% by weight of the reaction product from (I), from 10 to 80% by weight of (b2) and from 10 to 20% by weight of (a), with the percentages by weight being based on the total weight of the mixture comprising (a), (b2), (d), (e) and the reaction product from (I).
• the preferred thermoplastic polyurethanes preferably have a hardness of from Shore 45 A to Shore 78 D, particularly preferably from 50 A to 75 D.
• thermoplastic polyurethanes preferably comprise the following structural unit (II):
• R1, R2, R3 and X have the following meanings:
• the radical R1 is defined by the isocyanate used
• the radical R2 is defined by the reaction product of the thermoplastic polyester with the diol (c) in (1)
• the radical R3 is defined by the starting components (b2) and, if appropriate, (c) in the production of the TPU.
• thermoplastic polyurethanes TPUs
• TPUs Thermoplastic Polyurethanes
• polyurethanes (i) according to claim 1 a twin-screw extruder model ZE 40 A from Berstorff having a process section length of 35 D divided into 10 barrels was used.
• the screw element arrangement had two backward-conveying kneading blocks as melting unit for the TPU pellets in barrel 2 .
• Barrel 3 comprised a facility for adding liquid isocyanates to the TPU melt.
• Barrels 3 , 6 and 7 had mixing elements in the form of serrated disk blocks in addition to conventional transport elements.
• the barrel temperatures were initially all set to 210° C. and 15.0 kg/h of Elastollan® C 85 A pellets were fed continuously by gravimetric metering into barrel 1 .
• 5.0 kg/h of Lupranat® MM 103 were then introduced continuously into the TPU melt by means of a gear pump and gravimetric metering into barrel 3 and intensively mixed in in the subsequent barrels.
• all further barrel temperatures from barrel 4 onward were reduced to 150° C.
• the optically clear strands of melt leaving the extruder die head had reached temperatures of 150-160° C., they were cooled in a water bath, freed of adhering water in an extraction apparatus and pelletized in the usual way. This resulted in hard, nonsticky granules which crystallized readily and could be used without after-drying (concentrate No. 1).
• the reduced NCO content determined by analysis can be explained by water remaining in the pelletized material in an amount of 0.05-0.15% by weight leading to a reduction in the NCO content by reacting with NCO groups.
• thermoplastic polyurethanes (i) a twin-screw extruder model ZSK 58 from Werner & Pfleiderer having a process section length of 48 D divided into 12 barrels was used.
• the melt was discharged from the extruder by means of a heated gear pump, and pelletization was effected by means of a conventional underwater pelletization apparatus (UWP).
• UWP underwater pelletization apparatus
• the screw element arrangement corresponded to the arrangement described in example 1.
• the molecular weights Mn were determined in a customary way by means of gel permeation chromatography using dimethylformamide as solvent/eluent and mass calibration using narrow-distribution polymethyl methacrylate.
• Elastollan® C 80 A 10 pellets were mixed with pellets of concentrate No. 1 and concentrate No. 4 and these pellet mixtures were processed in a customary manner by injection molding to produce test plates, the test plates were heat treated at 100° C. for 20 hours and the mechanical properties were determined.
• the changes in the mechanical properties resulting from addition of the isocyanate concentrates are a reduction in the elongation at break, a decrease in the compression set values, in particular at 100° C., and an increase in the heat distortion resistance, measured by the VICAT A 120 value.
• thermoplastic polyurethanes (i) of the invention will keep without loss of effectiveness when stored correctly.
• Concentrate No. 4 obtained as described in example 3 was fed as a pellet mixture with Elastollan® 1195 A and Elastollan® 1154 D into an extruder having a groove feed zone, process section length of 32 D and a barrier mixing part screw, melted, mixed and extruded as a tube. Extrudates having a smooth surface were obtained.
• Elastollan® 1195 A and 1154 D were extruded in the same way without addition of concentrate No. 4. About 4 g of the extrudates were stirred in 50 ml of dimethylformamide for 14 hours and the proportions of soluble material were subsequently determined.
• Elastollan® 1174 D was processed in a customary manner by injection molding to produce plates. These plates were then printed using a thermotransfer color film (amine-comprising) for 2 minutes at 180° C. and cooled again. The plates prepared in this way were subsequently stored at 80° C. for 3 days. Diffusion of the dye of about 800 ⁇ m was determined on cross sections of these plates by means of optical microscopy. The printed image was blurred after the hot storage.
• Elastollan® 1174 D with addition of 5% of concentrate No. 4 obtained as described in example 3 was likewise processed as a pellet mixture by injection molding to produce plates, printed using thermotransfer color film and stored at 80° C. for 3 days in the same way as described in example 7.
• Diffusion of the dye of about 300 ⁇ m was determined on cross sections of these plates by means of optical microscopy. The printed image was sharp and had not run even after hot storage.
• Ultramid® B3 viz. a polyamide 6 from BASF, was shaped on a two-component injection molding machine to produce a plate having dimensions of 4 ⁇ 65 ⁇ 130 mm and Elastollan® C 78 A 10 as soft component was subsequently injected onto this hard Ultramid® B3 plate so that the two equal-sized plates were joined to one another over the cross-sectional area of 4 ⁇ 130 mm.
• Test bars S1 in accordance with DIN 53 504 were milled from these plates so that the interface was precisely in the middle of the S1 bar.
• the tensile strength i.e. the bond strength between Ultramid® B3 and Elastollan® C 78 A 10, was then tested in accordance with DIN 53 504.
• thermoplastic polyurethanes (i) of the invention Similar increases can be achieved when polybutylene terephthalate, polyethylene terephthalate, polycarbonate, ABS plastics, etc., are used as hard component.

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