Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F283/00—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G
  • C08F283/006—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G on to polymers provided for in C08G18/00
• • 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
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
  • C08K3/016—Flame-proofing or flame-retarding additives
• • 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
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/0066—Flame-proofing or flame-retarding additives
• • 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
  • C08K5/02—Halogenated hydrocarbons
• • 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

Definitions

• the invention relates to a polymer composition, in particular for injection molding applications, based on thermoplastic polyurethanes (TPU), a process for their preparation, moldings obtainable from the polymer composition, and their use in automotive, shoe manufacture, for sports and leisure applications, in agriculture and fishing.
• TPU thermoplastic polyurethanes
• Thermoplastic polyurethanes for injection molding applications are known. They can be processed on conventional injection molding, extrusion and blow molding equipment and are distinguished, for example, by outstanding elasticity, transparency, abrasion resistance and chemical resistance. TPUs are therefore used in automotive, footwear, sports and recreational applications, agriculture and fisheries.
• TPU is desirable, for example, to matt the TPU, improve surface properties for specific applications, or stiffen the material.
• TPU is only limitedly miscible with polystyrene and other radically polymerized polymers. If TPU compounded with more than 15 wt .-%, it comes in the injection of a delamination and thus to a drastic deterioration of the properties. The delamination can be visualized in a scanning electron microscope.
• FIG. 1 shows an SEM image of a
• thermoplastic polymer blends based on thermoplastic polyurethane and styrene polymer, foams produced therefrom and associated production processes.
• JP-A 1980-080440 describes a process for producing a polymer composition, wherein 20 to 80% by weight of TPU elastomer particles and 80 to 20% by weight of a styrene monomer or methacrylate ester are suspended in an aqueous medium and polymerized.
• JP-A 2007-231068 discloses expandable styrene-modified TPU particles containing 100 parts by weight of TPU and 20 to 300 parts by weight of a styrenic polymer with styrene polymer particles of 0.5 ⁇ m or less dispersed in the TPU. Although good results are already achieved with the known materials, there remains a wide scope for improvement, for example as regards the elasticity and transparency of such materials.
• the invention therefore relates to a polymer composition, in particular for injection molding applications, comprising at least one thermoplastic polyurethane (TPU) having a Vicat temperature (according to ISO 306 / A50) of below 80 ° C and 5 to 95 wt .-% of at least one by free radical polymerization obtainable polymer, based on the sum of TPU and the polymer obtainable by radical polymerization, wherein the polymer obtainable by free-radical polymerization is bonded as a comb, graft or copolymer to the TPU.
• TPU thermoplastic polyurethane
• the invention likewise relates to a molded article obtainable by injection molding of a polymer composition according to the invention and its use as cable insulation as well as material for the production of trailing cables, pneumatic hoses, spiral hoses, timing belts, delivery hoses and hydraulic hoses (top coverings).
• the invention further provides a process for preparing the polymer composition according to the invention, comprising the steps of: a) dispersing one or more TPUs having a Vicat temperature of less than 80 ° C., 5 to 95% by weight of one or more free-radically polymerizable monomers and optionally Comonomers, based on the sum of TPU and the monomers mentioned, a polymerization initiator, a dispersant and optionally further additives and / or polymerization aids in an aqueous medium at a temperature at which no substantial polymerization of free-radically polymerizable monomers takes place; b) optionally stirring the resulting dispersion for one to 24 hours at a temperature at which no substantial polymerization of the free radical polymerizable monomers takes place, and c) Polymerization of the radically polymerizable monomers in the form of a comb, graft or copolymer to the TPU.
• the invention likewise relates to a process for the preparation of a polymer composition, in particular for injection molding applications, comprising the steps of a) dissolving one or more TPUs having a Vicat temperature of less than 80 ° C. and optionally further additives and / or polymerization auxiliaries in a TPU suitable solvent, preferably THF or dioxane; b) heating the solution to a temperature at which the polymerization of the monomers fed in step c) takes place, c) feeding 5 to 95% by weight of one or more radically polymerizable monomers (based on the sum of TPU and the one or more radically polymerizable monomers) and of one or more polymerization initiators.
• a TPU suitable solvent preferably THF or dioxane
• TPU Thermoplastic polyurethanes
• processes for their preparation are known.
• TPU types are used with a Vicat temperature of less than 80 ° C, preferably from 60 to 79 ° C, particularly preferably from 60 to 75 ° C.
• the Vicat temperature refers to the TPU, not the combination of TPU and polymer, as will be apparent to those skilled in the art.
• the Vicat temperature is determined according to DIN EN ISO 306 according to method A50, i. determined with a force of 10 N and a heating rate of 50 ° C / h.
• a Vicat temperature according to the invention can be obtained by methods known to the person skilled in the art, for example by using corresponding monomer building blocks, in the preparation of the TPU (see below).
• TPU types used according to the invention preferably have a Shore A hardness in the range from 50 to 100, more preferably from 65 to 85 (measured to DIN 53505).
• the melting range (glass transition) is preferably in the range from -20 ° C to -60 ° C. It is preferably measured by means of differential scanning calorimetry (DSC), in particular at a heating rate of 10 ° C./min, for example according to ISO 1 1357 / -1 / -2.
• the elongation at break according to DIN 53504-S2 is preferably> 550%.
• TPU Vicat temperature
• TPU 100- 140 ° C; 0.1 -3 wt .-% peroxide initiator such as dicumyl peroxide
• free-radically polymerizable monomers having groups (alkoxide, epoxide, amine groups) which can undergo a polyaddition reaction with isocyanates are added in the preparation of the TPU according to known methods (see below).
• the following compounds are particularly preferred as monomers: hydroxyethyl methacrylate; 1, 2- and 1, 3-dihydroxypropyl methacrylate; Glycidyl methacrylate, ortho-, meta- and para-hydroxystyrene, meta- and para-aminostyrene, methacrylamide, 1,4-butenediol, 1,4-butynediol and / or polybutadiene diol.
• TPU and processes for their preparation have been described many times, for example Gerhard W. Becker and Dietrich Braun, Kunststoff Handbuch, Volume 7 "Polyurethane", Carl Hanser Verlag Kunststoff Vienna 1993.
• TPU is prepared by reacting from a mixture of isocyanates (a) with isocyanate-reactive compounds (b), preferably having a molecular weight of from 0.5 kg / mol to 10 kg / mol and optionally chain extenders (c), preferably one Molecular weight of 0.05 kg / mol to 0.5 kg / mol.
• At least one chain regulator (c1), a catalyst (d) and optionally at least one filler, auxiliary and / or additive are added to the mixture for the production of TPU.
• the substance groups which may also be indicated by the lower case letters, are also addressed as components.
• the components (a), (b), (c), (c1), (d) and (e) usually used in the preparation of the TPU are described below by way of example and comprise the following substance groups: isocyanates (a), relative to isocyanates reactive compounds (b), chain extenders (c), chain regulators (c1), catalysts (d) and / or at least one customary filler, auxiliary and / or additive.
• a mixture of isocyanates (a) and isocyanate-reactive compounds (b) is required for the preparation of TPU.
• component means in each case a single substance or a mixture of the substances belonging to this component.
• the components isocyanates (a), isocyanate-reactive compounds (b), and chain extenders (c) and, if used, the chain regulators (c1) are addressed as structural components.
• the organic isocyanates used are (a) aliphatic, cycloaliphatic, araliphatic and / or aromatic isocyanates, further preferred diisocyanates.
• diisocyanates examples are tri-, tetra-, penta-, hexa-, hepta- and / or octamethylene diisocyanate, 2-methylpentamethylene diisocyanate 1, 5, 2-ethylbutylene diisocyanate-1,4, pentamethylene diisocyanate-1,5, butylene diisocyanate 1, 4, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 1, 4 and / or 1, 3
• IPDI isophorone diisocyanate
• HXDI Bis (isocyanatomethyl) cyclohexane
• 1,4-cyclohexane diisocyanate 1,4-cyclohexane diisocyanate, 1-methyl-2,4- and / or 2,6-cyclohexane diisocyanate and / or 4,4'-, 2,4'- and 2,2 '-Dicyclohexylmethane diisocyanate, 2,2'-, 2,4'- and / or 4,4'-diphenylmethane diisocyanate (MDI), 1, 5-naphthylene diisocyanate (NDI), 2,4- and / or 2,6-tolylene diisocyanate ( TDI), diphenylmethane diisocyanate, 3,3'-dimethyldiphenyl diisocyanate, 1, 2-diphenylethane diisocyanate and phenylene diisocyanate.
• MDI 1, 5-naphthylene diis
• organic diisocyanates may optionally be present in minor amounts, e.g. in amounts of up to 3 mol%, preferably up to 1 mol%, based on the organic diisocyanate, be replaced by a tri- or higher-functional polyisocyanate, but its amount must be limited so that even thermoplastically processable polyurethanes are obtained.
• a greater amount of such more than difunctional isocyanates is suitably compensated by the concomitant use of less than difunctional compounds with reactive hydrogen atoms, so that too extensive chemical crosslinking of the polyurethane is avoided.
• polyetherols in preferred embodiments polyetherols, polyesterols, and / or polycarbonate diols, which are usually also included under the term "polyols", are used.
• TPU is preferably prepared from polyether alcohol, more preferably polyether diol is used.
• Suitable polyether can be prepared by known methods, for example by anionic polymerization of alkylene oxides with alkali metal hydroxides, such as sodium or potassium hydroxide, or alkali metal such as sodium, sodium or potassium or potassium isopropoxide, as catalysts and with the addition of at least one starter molecule, 2 to 3, preferably 2, containing reactive hydrogen atoms, or by cationic polymerization with Lewis acids as catalysts from one or more alkylene oxides having 2 to 4 carbon atoms in the alkylene radical.
• Suitable alkylene oxides are, for example, tetrahydrofuran, 1,3-propylene oxide and particularly preferably ethylene oxide and 1,2-propylene oxide.
• the alkylene oxides can be used individually, alternately in succession or as mixtures.
• Suitable starter molecules are, for example: water, organic dicarboxylic acids, such as succinic acid, adipic acid and preferably bivalent, optionally bonded ether bridges containing alcohols such as ethanediol, propanediol-1, 2, butanediol-1, 4, diethylene glycol, hexanediol-1, 6- and 2-methylpentanediol-1, 5.
• the starter molecules can be used individually or as mixtures.
• Particularly suitable and preferred are the hydroxyl-containing polytetrahydrofurans (PTHF).
• the substantially linear polyetherols usually have average molecular weights of from 500 to 8,000, preferably from 600 to 6,000, the PTHF having a preferred average molecular weight of from 500 to 2,500, especially from 800 to 2,000. They can be used both individually and in the form of mixtures with one another.
• a particularly preferred polyether diol is polytetrahydrofuran. Preference is given to using the polyether alcohols and polytetrahydrofuran having a molecular weight between 0.6 kg / mol and 2.5 kg / mol.
• the polyether alcohols are used individually or as a mixture of various polyether alcohols.
• TPU is made from polyester alcohol.
• polyester diol is used for this purpose.
• a preferred polyester diol is prepared from adipic acid and butane-1, 4-diol.
• Preferred embodiments of the polyester alcohols have a molecular weight between 0.6 kg / mol and 2.5 kg / mol.
• these polyols have molecular weights of 0.5 kg / mol to 8 kg / mol, preferably 0.6 kg / mol to 6 kg / mol, in particular 0.8 kg / mol to 4 kg / mol, and in further In a particularly preferred embodiment, the polyol is a polyester alcohol, preferably synthesized from polytetrahydrofuran, and has in a further preferred embodiment a molecular weight between 0.6 kg / mol and 2.5 kg / mol.
• chain extenders (c) in preferred embodiments, aliphatic, araliphatic, aromatic and / or cycloaliphatic compounds are used, which in further preferred embodiments have a molecular weight of from 0.05 kg / mol to 0.5 kg / mol.
• chain extenders (c) are compounds having two functional groups, for example diamines and / or alkanediols having 2 to 10 C atoms in the alkyl radical, in particular butanediol-1, 4, hexanediol-1, 6 and / or di- , Tri-, tetra-, penta-, hexa-, hepta-, octa-, nona- and / or Dekaalkylenglykole having 3 to 8 carbon atoms and corresponding oligo- and / or polypropylene glycols.
• mixtures of the chain extenders are used to prepare TPU.
• chain regulators (c1) usually having a molecular weight of 0.03 kg / mol to 0.5 kg / mol, are used.
• Chain regulators are compounds which have only one functional group compared to isocyanates. Examples of chain regulators are monofunctional alcohols, monofunctional amines, preferably methylamine, and / or monofunctional polyols. Through chain regulators, the flow behavior of the mixtures of the individual Components can be set specifically.
• Chain regulators are in preferred embodiments in an amount of 0 parts by weight to 5 parts by weight, more preferably from 0.1 parts by weight to 1 parts by weight, based on 100 parts by weight of the isocyanate-reactive compound b) used. Chain regulators are used in addition to or instead of chain extenders.
• At least one catalyst (d) is used for the production of TPU, in particular the reaction between the NCO groups of the diisocyanates (a) and the isocyanate-reactive compounds, preferably hydroxyl groups of the constituent components (b), (c) and c1 accelerates.
• the catalyst is selected from the group of tertiary amines, such as triethylamine, dimethylcyclohexylamine, N-methylmorpholine, ⁇ , ⁇ '-dimethylpiperazine, 2- (dimethylaminoethoxy) ethanol, diazabicyclo- (2,2,2 ) octane and similar substances.
• the at least one catalyst is selected from the group of organic metal compounds and is, by way of example, titanic acid ester, an iron compound such as iron (III) acetylacetonate, a tin compound, for example tin diacetate, tin dioctanoate, tin dilaurate or a tin dialkyl salt of an aliphatic carboxylic acid such as dibutyltin diacetate, dibutyltin dilaurate or the like.
• the catalysts are used individually, in other embodiments, mixtures of catalysts are used.
• the catalyst or mixture of catalysts is used in amounts of 0.0001 parts by weight to 0.1 parts by weight per 100 parts by weight of the isocyanate-reactive compound (b), preferably polyhydroxyl compound.
• auxiliary and / or additive examples include hydrolysis protection agents and flame retardants.
• Other additives and auxiliaries may be standard works such as o.g. Becker and Braun (1996).
• structural components (a) to (c) and optionally (c1) may also be added with hydrolysis protectants such as, for example, polymeric and low molecular weight carbodiimides.
• the structural components (b) and (c) can be varied in relatively wide molar ratios.
• the molar ratio of component (b) to the total chain extender (c) used is from 10: 1 to 1:10, preferably from 5: 1 to 1: 8, more preferably from 1: 1 to 1: 4 wherein the hardness of TPU increases with increasing content of chain extender (c).
• Shore hardnesses from A44 to D80 can be set in this way, and Shore hardnesses from A44 to A84 are particularly preferred. The Shore hardnesses are determined according to DIN 53505.
• the conversion to TPU takes place with customary characteristic numbers.
• the ratio is defined by the ratio of the total number of implementation th isocyanate groups of component (a) to the isocyanate-reactive groups, ie the active hydrogens, components (b) and (c).
• an isocyanate group of component (a) has an active hydrogen atom, ie, an isocyanate-reactive function, components (b) and (c).
• characteristic numbers above 100 more isocyanate groups than groups reactive toward isocyanates, for example OH groups, are present.
• the conversion to TPU is carried out at a ratio between 60 and 120, more preferably at a ratio between 80 and 1 10.
• TPU is preferably carried out according to one of the known methods mentioned below.
• Preferred embodiments are the continuous process, for example with reaction extruders, the belt process, the "one-shot” process or the prepolymer process, likewise preferred embodiments are the batch process or the prepolymer process process.
• the TPU thus obtained is extruded, cooled and granulated, and where appropriate it may be expedient to remove the resulting TPU in advance annealing at 80 ° C to 120 ° C, preferably at 100 ° C to 1 10 ° C for a period of 1 to 24 hours, i. give the mixture at constant temperature the opportunity to continue to react.
• Preferred TPU types have a greater proportion of the soft phase than the hard phase, preferably from 5 to 30% by weight, particularly preferably from 10 to 25% by weight, of the soft phase. Furthermore, the nitrogen content in the hard phase is preferably higher.
• Preferred TPU types are commercially available, for example, under the names Elastollan®1 170 AU, Elastastan®1 180, Elastollan®1 175 A 10W000 and Elastollan®880 A 13N000 from BASF Polyurethane GmbH, Lemförde, Germany.
• Elastollan® 170 AU a TPU consisting of the polytetrahydrofuran types 1000 and 2000 (the numbers are based on the molecular weight M w , the products are commercially available, for example, from BASF SE), a small proportion of 1, 4 Butanediol and 4,4'-diphenylmethane diisocyanate (MDI) is available.
• MDI 4,4'-diphenylmethane diisocyanate
• the polymer compositions according to the invention contain, in addition to the TPU, from 5 to 95% by weight (based on the sum of TPU and styrene polymers) of one or more polymers which can be obtained by free-radical polymerization and are bound to the TPU as comb, graft or copolymer. Preferably, their proportion is 80 to 30, more preferably 75 to 50, most preferably 75 to 65%.
• Polymers based on vinylically unsaturated monomers, for example (and preferably) styrene, acrylates and methacrylates, vinyl chloride, vinyl acetate, acrylonitrile and mixtures thereof are preferably used as polymers obtainable by free-radical polymerization.
• styrene polymer comprises polymers based on styrene, alpha-methylstyrene or mixtures of styrene and alpha-methylstyrene.
• Styrene polymers according to the invention are based on at least 50% by weight of styrene and / or alpha-methylstyrene monomers.
• Polystyrene, poly-alpha-methylstyrene and styrene-alpha are preferred as styrene polymers.
• Styrene-butadiene copolymers SB
• SAN styrene-acrylonitrile copolymers
• AMSAN acrylonitrile-alpha-methylstyrene copolymers
• SMA styrene-maleic anhydride copolymers
• SB styrene-methyl methacrylate copolymers
• SMMA styrene-N-phenylmaleimide copolymers
• SPMI styrene-N-phenylmaleimide copolymers
• ASA acrylonitrile-styrene-acrylic esters
• MBS methyl methacrylate-butadiene-styrene
• MABS methyl methacrylate-acrylonitrile-butadiene-styrene
• polystyrene i. the use of styrene monomer.
• the polymer compositions of the present invention are characterized by a unique TPU phase morphology consisting of a continuous phase of TPU homopolymer and a discontinuous phase of the graft polymer of TPU and the polymer obtainable by free-radical polymerization.
• the TPU phase ideally has a phase morphology as shown in FIG. 2 (TEM image).
• the graft polymer of TPU and the polymer obtainable by free-radical polymerization thereby forms round to elliptical discontinuous phases with a diameter between 50 and 500 nm. These are surrounded by a closed continuous TPU network.
• FIG. 2 shows the SEM image of a polymer composed of 40% by weight of TPU and 60% by weight of polystyrene.
• the polystyrene phase was contrasted with RuO 4 from the TPU phase.
• An essential element of the invention is that the above-described polymer structure can be obtained by radical polymerization of one or more monomers in the TPU network swollen by this monomer (s) or in a solvent in which the TPU is dissolved under suitable conditions.
• the compositions according to the invention are not expandable polymer particles.
• the polymer compositions according to the invention can also be used as blends with other polymers. The preparation methods for such blends are known to the person skilled in the art.
• the polymer compositions according to the invention preferably contain an additive component. Suitable additives are known to the person skilled in the art.
• At least one filler is added to the polymer composition.
• finely divided, inorganic solids such as talc, silica, mica, clay, zeolites, calcium carbonate, titanium dioxide, aluminum powder and / or mineral fillers such as glass fibers can be used as fillers in amounts of generally from 0.1 to 10% by weight. , preferably 0.1 to 3 wt .-%, particularly preferably 0.1 to 1, 5 wt .-%, based on the polymer composition are used.
• further additives such as plasticizers, flame retardants, carbon black for coloring, soluble and insoluble dyes, pigments, UV stabilizers and / or thermal stabilizers may be added.
• UV stabilizers has proved to be advantageous. Especially with polymers such as SMA, strong UV radiation leads to visible yellowing and chemical conversion of the material, which is accompanied by significant embrittlement. Reactivity plays a crucial role in the selection of suitable UV stabilizers. While stabilizers based on benzotriazoles such as Tinuvin 234 can improve the UV resistance without changing the processing properties, stabilizers based on sterically hindered amines such as Uvinul 4050 and Tinuvin 770 are less suitable for the polymer compositions according to the invention.
• the granulate according to the invention preferably contains as additive a UV stabilizer based on benzotriazoles in amounts in the range of 0.05 to 5 parts by weight, preferably 0.1 to 1 part by weight, based on 100 parts by weight of polymer.
• Suitable flame retardants are, for example, tetrabromobisphenol A, brominated polystyrene oligomers, brominated butadiene-polystyrene copolymers according to WO 2007/058736, tetrabromobisphenol A diallyl ether and hexabromocyclododecane (HBCD), in particular the industrial products which essentially contain the o, ß- and ⁇ -isomer and an addition of synergists such as dicumyl.
• tetrabromobisphenol A brominated polystyrene oligomers, brominated butadiene-polystyrene copolymers according to WO 2007/058736
• tetrabromobisphenol A diallyl ether hexabromocyclododecane
• brominated aromatics such as tetrabromobisphenol A, and brominated styrene oligomers.
• Suitable halogen-free flame retardants are, for example, expandable graphite, red phosphorus and phosphorus compounds, such as triphenyl phosphate and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.
• Preferred phosphorus compounds are tris (2-chloroisopropyl) phosphate, phosphoric acid triethyl ester, diethyl ethyl phosphonate, cresyl diphenyl phosphates, Exolit OP560, phosphoric acid 6- (diphenoxy-phosphoryloxy) -hexahydro-furo [3,2-b] -furan-3-yl- ester diphenyl ester, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide or 6H-dibenz [c, e] [1, 2] oxaphosphorine 6-oxide.
• the abovementioned flame retardants can either be dissolved in the monomers before the beginning of the polymerization or be incorporated into the TPU by extrusion.
• the total amount of additives is generally 0 to 5 wt .-%, preferably 0 to 0.5 wt .-%, based on the total weight of the polymers used.
• the polymer compositions according to the invention are obtainable by a process for preparing the process comprising the steps of a) dispersing one or more TPUs having a Vicat temperature of less than 80 ° C., 5 to 95% by weight of one or more free-radically polymerizable monomers and optionally comonomers to the sum of TPU and said monomers, a polymerization initiator, a dispersing agent and optionally further additives and / or polymerization aids in an aqueous medium at a temperature at which no substantial polymerization of the radically polymerizable monomers takes place; b) optionally agitating the resulting dispersion for one to 24 hours at a temperature at which no substantial polymerization of the free-radically polymerizable monomers takes place, and c) polymerizing the radically polymerizable monomers in the form of a comb, graft or copolymer to the TPU.
• the process preferably consists of the steps a) to c).
• styrene is preferably used according to the above.
• other radically polymerizable monomers such as alkylstyrenes, divinylbenzene, 1,4-butanediol dimethacrylate, acrylonitrile, diphenyl ether or ⁇ -methylstyrene and acrylates can also be used.
• the customary auxiliaries such as peroxide initiators, suspension stabilizers, chain transfer agents and plasticizers can be added.
• auxiliaries and additives may be added to the suspension in amounts of from 3 to 15% by weight, based on the sum of monomer and TPU. It can be added before, during or after the polymerization of the suspension. It is advantageous to use inorganic Pickering dispersants, for example magnesium pyrophosphate or calcium phosphate, as suspension stabilizers.
• the used TPU before it is used in the polymerization, can be processed by underwater granulation to give a minigranulate having an average diameter of 0.5 to 1.5 mm.
• nucleating agents such as talc or polyethylene waxes can be incorporated in amounts of from 0.01 to 15% by weight into the polyurethane used by extrusion.
• a preferred embodiment of the process is characterized in that first an aqueous phase which contains 0.1 to 10% by weight of the abovementioned Pickering stabilizers, 0.1 to 0.001% by weight of a surfactant (for example sodium dodecylsulfonate) and 1 to 90% by weight.
• a surfactant for example sodium dodecylsulfonate
• the monomer which optionally contains the abovementioned auxiliaries, such as initiators and flame retardants, is metered into the stirred reactor at room temperature or below the polymerization temperature.
• the TPU is first combined at room temperature with the monomer containing the above-mentioned adjuvants such as initiators and optionally flame retardants in the absence of water and allowed to swell for 0.5 to 24 hours. Subsequently, the granules which have been swollen by monomer are likewise transferred into the polymerization reactor in which the aqueous phase with the abovementioned Pickering stabilizer and the surfactant is located.
• substantially circular particles having a mean diameter in the range of 0.5 to 4 mm are formed when microgranular TPU is used and 0.5 to 2 cm in size when microgranulation of the TPU is omitted. They can be coated with the usual coating agents, for example finely divided silicates. In this case, it has proven to be particularly practical to coat the polymer with 0.1 to 1% by weight of hydrophilic silica (Sipernat® FK320, from Evonic).
• the invention further provides a process for preparing a polymer composition, in particular for injection molding applications, comprising the steps of a) dissolving one or more TPUs having a Vicat temperature of less than 80 ° C and optionally further additives and / or polymerization aids in a solvent; b) heating the solution to a temperature at which the polymerization of the monomers fed in step c) takes place, c) feeding 5 to 95% by weight of one or more radically polymerizable monomers (based on the sum of TPU and the one or more radically polymerizable monomers) and of one or more polymerization initiators.
• the process preferably consists of the steps a) to c).
• solution polymerization according to the invention is preferably used in accordance with the above styrene alone.
• radically polymerizable monomers such as alkylstyrenes, divinylbenzene, 1,4-butanediol dimethacrylate, acrylonitrile, diphenyl ether or ⁇ -methylstyrene and acrylates can be used.
• Suitable solvents are, for example, cyclic ethers, preferably THF and dioxane, more preferably dioxane.
• the usual auxiliaries such as peroxide initiators, chain transfer agents and plasticizers can be added.
• auxiliaries and additives mentioned can be added to the solution in amounts of from 3 to 15% by weight, based on the sum of monomer and TPU. It can be added to the solution before, during or after the polymerization.
• a preferred embodiment of the process is characterized in that initially TPU dissolved in the solvent (for example dioxane or THF) is introduced into a stirrable pressure autoclave. Subsequently, it is raised to a temperature at which the polymerization of the radically polymerizable monomers takes place (preferably 95 to 130 ° C.). Then, a solution of the polymerization initiator (preferably dibenzoyl peroxide or dicumyl peroxide) in the free-radically polymerizable monomer (preferably styrene) is slowly added continuously. After stirring for several hours, a smaller amount of polymerization initiator is added again and stirring is continued for several hours.
• the polymer composition according to the invention can be isolated by removal of the solvent.
• the polymer compositions prepared by solution polymerization show an even finer phase distribution between TPU homopolymer and TPU graft polymer.
• the polymer composition of the invention is particularly suitable for the production of moldings by injection molding.
• moldings according to the invention are suitable, for example, for applications in the automotive industry, shoe production, in the sports and leisure sector, in agriculture and in fisheries. The invention is explained in more detail by the examples.
• MPP precipitation In Examples 1 to 4, an amorphous MPP precipitate was used as Pickering stabilizer. It is crucial that the MPP precipitation used was freshly prepared (maximum 12 hours old), since otherwise sufficient stabilization of the reaction mixtures can not take place.
• the MPP precipitation can be prepared as follows:
• the swollen TPU was transferred to a 6 l pressure autoclave [EPS reactor, maximum pressure: 20 bar, paddle stirrer (stirrer speed 300 rpm) in which 3 kg of deionized water, 803 g of MPP precipitate and 42 g of 2% strength solution of the emulsifier E30 (manufactured from E30-40 from Leuna Tenside GmbH). After the reactor was closed and exposed to nitrogen (inerting), the following temperature profile was started:
• Example 1 was repeated, using instead of Elastollan 1 170AU microgranulate from Elastollan 1 180A.
• FIG. 1 shows the SEM image of one of the polymers from Example 2 (40% by weight of polystyrene). The polystyrene phase was contrasted with RuO 4 from the TPU phase.
• Example 3 Preparation of TPU Polystyrene 40:60 Copolymer
• Example 1 was repeated with the following quantities of starting material:
• Example 2 was repeated. Instead of Elastollan 1 170AU, microgranulate from Elastollan 1 180A was used.
• FIG. 2 shows the SEM image of an injection-molded body from example 3 (40% by weight TPU 60% by weight polystyrene). The polystyrene phase was contrasted with RuO 4 from the TPU phase.
• FIG. 3 shows PS / TPU graft polymer 54:46 according to Example 5 after injection molding.
• Example 6 was repeated, but the extruder was charged with 17 g of a mixture of polystyrene 158 K (Styrolution) and Elastollan 1 170AU.
• FIG. 4 shows the SEM image of a blend (extrusion temperature 190 ° C.) of TPU (Elasto-Man 1 170AU) and polystyrene according to Comparative Example 1.
• the polystyrene phase was contrasted with RuO 4 from the TPU phase.
• the elongation at maximum force (measured according to IS0527-2) serves:

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• 2014
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