WO2013113846A1

WO2013113846A1 - Electromechanical converter comprising a polyurethane polymer having polyester and/or polycarbonate units

Info

Publication number: WO2013113846A1
Application number: PCT/EP2013/051956
Authority: WO
Inventors: Joachim Wagner; Sebastian Dörr; Werner Jenninger
Original assignee: Bayer Intellectual Property Gmbh
Priority date: 2012-02-01
Filing date: 2013-01-31
Publication date: 2013-08-08
Also published as: TW201343699A

Abstract

The present invention relates to an electromechanical converter comprising a dielectric elastomer contacted by a first electrode and a second electrode, wherein the dielectric elastomer comprises a polyurethane polymer. In this case, the polyurethane polymer comprises at least one polyester and/or polycarbonate unit. The invention further relates to a method for producing such an electromechanical converter, the use of the inserted dielectric elastomer and an electrical and/or electronic device comprising an electromechanical converter according to the invention.

Description

Electromechanical transducer comprising a polyurethane polymer with polyester and / or

Polycarbonate units

The present invention relates to an electromechanical transducer comprising a dielectric elastomer contacted by a first electrode and a second electrode, the dielectric elastomer comprising a polyurethane polymer. The polyurethane polymer here comprises at least one polyester and / or polycarbonate unit. The invention further relates to a method for producing such an electromechanical transducer, the use of the dielectric elastomer used and an electrical and / or electronic device comprising an electromechanical transducer according to the invention. Electromechanical transducers play an important role in converting electrical energy into mechanical energy and vice versa. Electromechanical converters can therefore be used as sensors, actuators and / or generators. As an example of this, the systems mentioned in WO-A 2001/006575 are presented, which use prestressed polymers.

One class of such transducers is based on electroactive polymers. It is a constant goal to increase the properties of the electroactive polymers, in particular the electrical resistance and the breakdown strength. At the same time, however, the mechanics of the polymers make them suitable for use in electromechanical transducers.

One way to increase the dielectric constant is to add certain fillers. Thus, WO-A 2008/095621 describes soot-filled polyurethane compositions which at least consist of polyetherurethanes incorporated with polyol components containing from 50 to 100% by weight of polyalkylene oxides prepared by DMC catalysis, in particular polypropylene oxides, and 0-50% by weight. % of catalyst-free polyols, in particular those which are purified by distillation or by recrystallization, or those which have not been prepared by ring-opening polymerization of oxygen heterocycles constructed. Furthermore, the polyurethane compositions contain 0.1-30 wt .-% carbon black.

Energy converters of film-forming aqueous polyurethane dispersions are disclosed in WO-A 2009/074192. Again, the high dielectric constants and the good mechanical properties of the resulting polyurethane films are highlighted.

US-A 5977685, JP-A 07240544, JP-A 06085339 and JP-B 3026043 disclose electromechanical transducers comprising a polyurethane elastomer prepared from macromolecular polyols, organic polyisocyanates and compounds of the Chain extension, wherein the molar ratio of the NCO groups of the polyisocyanate to the OH groups of the polyol is in the range of 1.5 to 9.

The not yet published application with the application number PCT / EP2011 / 063571 discloses electromechanical transducer containing various polyurethane elastomers, which generally have very high electrical resistances and breakdown field strengths. The mechanical properties of these elastomers show, in part, a combination of low elongations with low tear strengths and high tear strengths with high levels of permanent elongation. References to the combination of low permanent strains and comparatively high tear strengths, which is particularly important for use as a mechanical-electrical energy converter, are not disclosed. High tear propagation resistance means that in the case of a dielectric breakdown during operation of the electromechanical transducer, the foils do not spontaneously tear through and thus the electromechanical transducer completely loses its function.

However, there is a need for electromechanical transducers with dielectric elastomers which, in addition to the known properties, such as high electrical resistances and high breakdown field strengths, have increased tear propagation resistance and thus increased stability over the dielectric breakdown in comparison to the systems known hitherto.

The invention therefore proposes an electromechanical transducer comprising a dielectric elastomer contacted by a first electrode and a second electrode, wherein the dielectric elastomer comprises a polyurethane polymer. The converter according to the invention is characterized in that the polyurethane polymer is obtainable from the reaction of

A) a polyisocyanate and / or B) a polyisocyanate prepolymer with C) a compound having at least two isocyanate-reactive groups, wherein the polyisocyanate prepolymer B) and / or the compound having at least two isocyanate-reactive groups C) polycarbonate and / or polyester Units, wherein the polycarbonate units contain hydroxyl-containing polycarbonate polyols having an even number of CH ₂ groups between the hydroxyl groups, and / or the polyester units on the reaction of adipic acid and / or adipic anhydride with diols having an even number based on CH ₂ groups between the hydroxyl groups, wherein for the preparation of the polyurethane polymer no further isocyanate-reactive compounds in addition to the component C) are used, and wherein the molar ratios of isocyanate groups in A) and / or B to isocyanate-reactive groups in C) of 0.8: 1.0 to 1 , 3: 1.0, preferably 0.9: 1.0 to 1.2: 1.0.

Surprisingly, it has been found that the polyurethane polymers provided in the electromechanical converter according to the invention have particularly high tear propagation strengths with simultaneously small remaining elongations. At the same time, the polyurethanes are present as soft elastomers. The combination of these properties results in an advantageous use in electromechanical transducers.

When a mechanical stress is applied to such a transducer, the transducer deforms along its thickness and area, for example, and a strong electrical signal can be detected at the electrodes. This converts mechanical energy into electrical energy. The converter according to the invention can consequently be used both as a generator and as a sensor.

On the other hand, taking advantage of the opposite effect, namely the conversion of electrical energy into mechanical energy, the converter according to the invention can equally serve as an actuator.

As electrodes, basically all materials are suitable which have a sufficiently high electrical conductivity and can advantageously follow the expansion of the dielectric elastomer. By way of example, the electrodes can be constructed from an electrically conductive polymer, from lead ink or from carbon black.

Dielectric elastomers for the purposes of the present invention are elastomers that can change their shape by the application of an electric field. For example, in the case of elastomeric films, the thickness may decrease while at the same time extending the film lengthwise in the planar direction.

The thickness of the dielectric elastomer layer is preferably> 1 μιη to <500 μιη and more preferably> 10 μιη to <150 μιη. It can be constructed in one piece or in several pieces. For example, a multi-piece layer can be obtained by laminating individual layers. The dielectric elastomer may have other ingredients in addition to the inventively provided polyurethane polymer. Such ingredients include, for example, crosslinkers, thickeners, cosolvents, thixotropic agents, stabilizers, antioxidants, light stabilizers, emulsifiers, surfactants, adhesives, plasticizers, water repellents, pigments, fillers and leveling agents.

For example, fillers in the elastomer can regulate the dielectric constant of the polymer. Examples of these are ceramic fillers, in particular barium titanate, titanium dioxide and piezoelectric ceramics such as quartz or lead zirconium titanate, as well as organic fillers, in particular those having a high electrical polarizability, for example phthalocyanines.

In addition, a high dielectric constant can also be achieved by introducing electrically conductive fillers below their percolation threshold. Examples of these are carbon black, graphite, single-walled or multi-walled carbon nanotubes, electrically conductive polymers such as polythiophenes, polyanilines or polypyrroles, or mixtures thereof. Of particular interest in this connection are those types of carbon black which have a surface passivation and therefore at higher concentrations below the percolation threshold increase the dielectric constant and nevertheless do not lead to an increase in the conductivity of the polymer.

The polyurethane polymer provided in the electromechanical converter according to the invention is obtainable from the reaction of a polyisocyanate A) and / or a polyisocyanate prepolymer B) with a compound C) which comprises at least two isocyanate-reactive groups, with no further isocyanate-reactive for the preparation of the polyurethane polymer Compounds in addition to component C) are used and wherein the molar ratios of isocyanate groups in A) and / or B) to isocyanate-reactive groups in C) of 0.8: 1.0 to 1.3: 1.0, preferably 0, 9: 1.0 to 1.2: 1.0. In this case, B) and / or C) have polycarbonate and / or polyester units, wherein the polycarbonate units contain hydroxyl-containing polycarbonate polyols which have an even number of CH 2 groups between the hydroxyl groups, and / or the polyester units the reaction of adipic acid and / or adipic anhydride with diols having an even number of CH ₂ groups between the hydroxy groups. The following possibilities arise for incorporation of the polycarbonate and / or polyester units according to the invention in the polyurethane polymer: A) + C) with polycarbonate and / or polyester units in C); B) + C) with polycarbonate and / or polyester units in B); B) + C) with polycarbonate and / or Polyester units in C); B) + C) with polycarbonate and / or polyester units in B) and C); A) + B) + C) with polycarbonate and / or polyester units in B); A) + B) + C) with polycarbonate and / or polyester units in C) and finally A) + B) + C) with polycarbonate and / or polyester units in B) and C). The polycarbonate and / or polyester units according to the invention can be obtained by known methods, for example from the reaction of polyisocyanates A) and / or polyisocyanate prepolymers B) with the corresponding polycarbonate polyols and / or polyester polyols. These polycarbonate polyols and / or polyester polyols can also be used to form the prepolymers. Examples of suitable polyisocyanates A) according to the invention are 1,4-butylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), 2,2,4 and / or 2,4,4-trimethylhexamethylene diisocyanate, the isomeric bis (4, 4'-isocyanatocyclohexyl) methanes or mixtures thereof of any isomer content, 1,4-cyclohexylene diisocyanate, 4-isocyanatomethyl-1,8-octane diisocyanate (nonane triisocyanate), 1,4-phenylene diisocyanate, 2,4- and / or 2,6-toluene diisocyanate, 1,5-naphthylene diisocyanate, 2,2'- and / or 2,4'- and / or 4,4'-diphenylmethane diisocyanate, 1,3- and / or l, 4-bis (2-isocyanato-prop-2 -yl) -benzene (TMXDI), 1, 3-bis (isocyanatomethyl) benzene (XDI), alkyl 2,6-diisocyanatohexanoate (lysine diisocyanates) having alkyl groups of 1 to 8 carbon atoms and mixtures thereof. Furthermore, uretdione, isocyanurate, biuret, iminooxadiazinedione or oxadiazinetrione-containing compounds based on the diisocyanates mentioned are suitable building blocks of component A). Preference is given to using components based on 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), bis (4,4'-isocyanatocyclohexyl) methane, tolylene diisocyanate and / or diphenylmethane diisocyanate, particularly preferably 1,6-hexamethylene diisocyanate (HDI).

The polyisocyanate prepolymers which can be used as component B) can be obtained by reacting one or more of the abovementioned diisocyanates with one or more hydroxy-functional, in particular polymeric, polyols, if appropriate with addition of catalysts and auxiliaries and additives. In addition, components for chain extension for the formation of the polyisocyanate prepolymer can be used in addition, such as components having primary and / or secondary amino groups. Hydroxy-functional, polymeric polyols for the conversion to the polyisocyanate prepolymer B) according to the invention include, for example, polyester polyols, polyacrylate polyols, polyurethane polyols, polycarbonate polyols, polyether polyols, polyester polyacrylate polyols, polyurethane polyacrylate polyols, polyurethane polyester polyols, polyurethane polyether polyols and / or polyurethane polycarbonate polyols and / or polyester polycarbonate polyols. These can be used to prepare the polyisocyanate prepolymer individually or in any mixtures with each other.

For the preparation of the polyisocyanate prepolymers B) it is possible to use diisocyanates with the polycarbonate polyols containing an even number of CH ₂ groups and / or polyester polyols based on the reaction of adipic acid and / or adipic anhydride with diols having an even number of CH ₂ - Groups, to be implemented.

To prepare the polyisocyanate prepolymers B), diisocyanates may be reacted with the polyols at a ratio of the isocyanate groups to hydroxyl groups (NCO / OH ratio) of 2: 1 to 20: 1, preferably of 8: 1 to 15: 1. In this case, urethane and / or allophanate structures can be formed. The proportion of unreacted polyisocyanates can then be separated off. For this purpose, for example, a thin-film distillation can be used, with residual monomer low products with residual monomer contents of, for example, <1 weight percent, preferably <0.5 weight percent, more preferably <0.1 weight percent, are obtained. The reaction temperature may be from 20 ° C to 120 ° C, preferably from 60 ° C to 100 ° C, amount. Optionally, stabilizers such as benzoyl chloride, isophthaloyl chloride, dibutyl phosphate, 3-chloropropionic acid or methyl tosylate may be added during the preparation.

Components suitable for chain extension in the polyisocyanate prepolymers B) according to the invention are organic di- or polyamines. For example, ethylenediamine, 1, 2-diaminopropane, 1, 3-diaminopropane, 1, 4-diaminobutane, 1, 6-diaminohexane, isophoronediamine, isomer mixture of 2,2,4- and 2,4,4-trimethylhexamethylenediamine, 2-methylpentamethylene - Diamine, diethylenetriamine, diaminodicyclohexylmethane or dimethylethylenediamine or mixtures thereof are used. In addition, it is also possible to use compounds which, in addition to a primary amino group, also have secondary amino groups or, in addition to an amino group (primary or secondary), OH groups, for the preparation of the polyisocyanate prepolymers B). Examples of these are primary / secondary amines, such as diethanolamine, 3-amino-1-methylaminopropane, 3-amino-1-ethylaminopropane, 3-amino-1-cyclohexylaminopropane, 3-amino-1-methylaminobutane, alkanolamines such as N-aminoethylethanolamine, ethanolamine , 3-aminopropanol, neopentanolamine. For chain termination are usually amines with an isocyanate-reactive group such as methylamine, ethylamine, propylamine, Butylamine, octylamine, laurylamine, stearylamine, isononyloxypropylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, N-methylaminopropylamine,

Diethyl (methyl) aminopropylamine, morpholine, piperidine, or suitable substituted derivatives thereof, amide amines from diprimary amines and monocarboxylic acids, monoketim of diprimary amines, primary / tertiary amines, such as Ν, Ν-dimethylaminopropylamine used.

The polyisocyanate prepolymers or mixtures thereof used according to the invention as component B) preferably have an average NCO functionality of> 1.8 to <5, more preferably> 2 to <3.5 and very particularly preferably> 2 to <2.5 ,

In the context of the present invention, component C) may in principle be a compound having at least two isocyanate-reactive groups, preferably amino and / or hydroxyl groups, particularly preferably hydroxy groups. For example, component C) may be a polyol having at least two isocyanate-reactive hydroxyl groups, such as, for example, trimethylolpropane (TMP).

Polyester components which can be used as component C) and / or for the preparation of component B) are the known polycondensates of di- and optionally tri- and tetraols and di- and optionally tri- and tetracarboxylic acids or hydroxycarboxylic acids or lactones , Instead of the free polycarboxylic acids, it is also possible to use the corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic acid esters of lower alcohols for the preparation of the polyesters. Polyester polyols having number-average molecular weights M _{n of} from 1000 to 10000 g / mol, preferably from 1500 to 4000 g / mol, particularly preferably from 1800 to 2300 g / mol, may be used.

M _n is determined by gel permeation chromatography (GPC) at 23 ° C in THF using as calibration relationship polystyrene standards in the relevant molecular weight range. Examples of suitable diols for the preparation of the polyester polyols are those which have an even number of CH ₂ groups between the hydroxyl groups, for example ethylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycols such as polyethylene glycol, butanediol (1,3), butanediol (1 , 4), hexanediol (1,6). Preference is given to hexanediol (1,6), butanediol (1,4) and ethylene glycol, particularly preferred are hexanediol (1,6) and ethylene glycol.

The polyester polyols are preferably obtainable as component C) and / or for the preparation of component B) by reacting adipic acid and / or adipic anhydride with Diols which have an even number of CH ₂ groups between the hydroxyl groups, particularly preferably with hexanediol (1,6), butanediol (1,4) and ethylene glycol and very particularly preferably with hexanediol (1,6) and ethylene glycol.

Polycarbonate components which can be used as component C) and / or for the preparation of component B) are hydroxyl-containing polycarbonate polyols, preferably polycarbonate diols having an even number of CH ₂ groups between the hydroxyl groups, with number-average molecular weights M _n of 1000 to 10000 g / mol, preferably from 1500 to 4000 g / mol, particularly preferably from 1800 to 3000 g / mol. These are obtainable by reaction of carbon dioxide, carbonic acid derivatives, such as diphenyl carbonate, dimethyl carbonate or phosgene, with polyols, preferably diols, which have an even number of CH ₂ groups between the hydroxyl groups.

Examples of such diols are ethylene glycol, 1,3- and 1, 4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1, 4-bishydroxymethylcyclohexane, dibutylene glycol and polybutylene glycols. Preference is given to ethylene glycol, 1,3- and 1,4-butanediol and 1,6-hexanediol. Preferably, the diol component contains 40 to 100 wt .-% of hexanediol, preferably 1,6-hexanediol and / or hexanediol derivatives. Such hexanediol derivatives are based on hexanediol and have ester or ether groups in addition to terminal OH groups. Such derivatives are obtainable by reaction of hexanediol with excess caprolactone or by etherification of hexanediol with itself to di- or trihexylenglykol. Particularly preferred is 1,6-hexanediol as the diol component.

Of course, the aforementioned conditions regarding the presence and shape of polycarbonate and / or polyester units in the polyurethane polymer apply.

If a mixture of component A) and component B) is used, the equivalent ratio of the isocyanate groups from A) to the isocyanate groups from B) is advantageously between> 1:10 to <10: 1, more preferably> 1: 5 <5: 1, and most preferably> 1: 3 to <3: 1.

In the context of the present invention, the terms "a" and "an" in connection with the components A), B) and C) are not used as number words but as an indefinite article. In one embodiment of the electromechanical transducer according to the invention, the polyurethane polymer is obtainable from the reaction of a polyisocyanate prepolymer B) with a compound having at least two NCO-reactive groups C).

Preferred in this embodiment is that the polyurethane prepolymer B) is obtainable from the reaction of a diisocyanate A) with a polycarbonate polyol containing an even number of CH ₂ groups, and / or a polyesterpolyol, based on the reaction of adipic acid and / or adipic anhydride with diols having an even number of CH ₂ groups, particularly preferably used as diisocyanate A) hexamethylene diisocyanate.

In a further embodiment of the electromechanical transducer according to the invention, the polyurethane polymer is obtainable from the reaction of a polyisocyanate prepolymer B) with C) a polycarbonate polyol containing an even number of CH 2 groups and / or a polyester polyol based on the reaction of adipic acid and / or adipic anhydride with diols having an even number of CH ₂ groups and the polyisocyanate prepolymer B) is obtainable from the reaction of an at least difunctional polyisocyanate with a polycarbonate polyol containing an even number of CH ₂ groups, and / or a polyester polyol based on the reaction of adipic acid and / or adipic anhydride with diols having an even number of CH ₂ groups, particularly preferably the diisocyanate A) used is the monomer and / or trimerizate (biuret or isocyanurate) of hexamethylene diisocyanate. Here, the polycarbonate polyol and / or the polyester polyol serves both for the construction of the prepolymer and for its chain extension.

In one embodiment of the electromechanical transducer according to the invention in the polyurethane polymer, the proportion of polyester and / or polycarbonate units is> 20% by weight to <90% by weight. This proportion is preferably between> 25% by weight and <80% by weight and more preferably between> 30% by weight and <50% by weight. In a further embodiment of the electromechanical transducer according to the invention, the polyurethane polymer has a modulus of elasticity at an elongation of 50%>from> 0.1 MPa to <15 MPa. The module is determined according to DIN EN 150 672 1-1 and can also be> 0.2 MPa to <5 MPa. Furthermore, the polyurethane polymer may have a maximum stress of> 0.2 MPa, in particular of> 0.4 MPa to <50 MPa and a maximum elongation of>200%>, in particular of>350%>. In addition, the polymer element according to the invention in the use stretch range of> 50% to <200%, a tension of> 0.1 MPa to <10 MPa, for example from> 0, 15 MPa to <5 MPa, in particular of 0.2 MPa to <3 MPa, have (determination according to DIN 53504). The polyurethane polymer contained in the electromechanical transducer according to the invention has a tensile strength of> 1, 5kN / m, preferably of> 1.6 kN / m. The tear strength was determined according to ASTM D 624-00 on films of thickness from 30 μιη to 200 μιη. A further subject of the present invention is a method for producing an electromechanical transducer, comprising the steps:

1) providing a first electrode and a second electrode;

2) providing a dielectric elastomer, wherein the dielectric elastomer comprises a polyurethane polymer, and the polyurethane polymer is obtainable from the reaction of

A) a polyisocyanate and / or B) a polyisocyanate prepolymer with C) a compound having at least two isocyanate-reactive groups, wherein the polyisocyanate prepolymer B) and / or the compound having at least two isocyanate-reactive groups C) polycarbonate and / or polyester Units, wherein the polycarboxylate units contain hydroxyl-containing polycarbonate polyols having an even number of CH 2 groups between the hydroxyl groups, and / or the polyester units on the reaction of adipic acid and / or adipic anhydride with diols which are based on an even number of CH ₂ groups between the hydroxyl groups, wherein for the preparation of the polyurethane polymer, no further isocyanate-reactive compounds in addition to the component C) are used, and wherein the molar ratios of isocyanate groups in A) and / or B to to isocyanate-reactive groups in C) of 0.8: 1.0 to 1.3: 1.0, preferably 0.9: 1.0 to 1.2: 1.0.

3) placing the dielectric elastomer between the first electrode and the second electrode. Details of the polyurethane polymer including the embodiments have already been described in connection with the device according to the invention. To avoid unnecessary repetition, reference is made to the process with respect to this.

In the process according to the invention, the provision of the dielectric elastomer is preferably carried out by applying the reaction mixture leading to the polyurethane polymer to the first and / or second electrode. The advantage of this procedure is in particular that the curing elastomer can build a good adhesion to the electrodes.

The application of the reaction mixture can be carried out, for example, by knife coating, brushing, pouring, spinning, spraying or extrusion. Preferably, drying and / or tempering is carried out after application of the reaction mixture. The drying / tempering can take place in a temperature range from 0 ° C to 200 ° C, for example for 0.1 min to 48 h, in particular for 6 h to 18 h; drying / heat treatment for a period of 15 minutes to 30 minutes in the temperature range from 60 ° C. to 120 ° C. is particularly preferred. The present invention further relates to the use of a dielectric elastomer as an actuator, sensor and / or generator in an electromechanical transducer, wherein the dielectric elastomer comprises a polyurethane polymer, and the polyurethane polymer is obtainable from the reaction of

A) a polyisocyanate and / or B) a polyisocyanate prepolymer with C) a compound having at least two isocyanate-reactive groups, wherein the polyisocyanate prepolymer B) and / or the compound having at least two isocyanate-reactive groups C) polycarbonate and / or polyester Units, wherein the polycarbonate units contain hydroxyl-containing polycarbonate polyols having an even number of CH ₂ groups between the hydroxyl groups, and / or the polyester units on the reaction of adipic acid and / or adipic anhydride with diols having an even number based on CH ₂ groups between the hydroxyl groups based, wherein for the preparation of the polyurethane polymer no further isocyanate-reactive compounds in addition to the component C) are used, and wherein the molar ratios of isocyanate groups in A) and / or B to isocyanate-reactive groups in C) are from 0.8: 1.0 to 1.3: 1.0, preferably 0.9: 1.0 to 1.2: 1.0.

The present invention further relates to the use of a dielectric elastomer as an actuator, sensor and / or generator in an electromechanical transducer, wherein the dielectric elastomer comprises a polyurethane polymer, and the polyurethane polymer is obtainable from the reaction of

A) a polyisocyanate and / or B) a polyisocyanate prepolymer with C) a compound having at least two isocyanate-reactive groups, wherein the polyisocyanate prepolymer B) and / or the compound having at least two isocyanate-reactive groups C) polycarbonate and / or polyester Units, wherein the polycarbonate units contain hydroxyl-containing polycarbonate polyols having an even number of CH ₂ groups between the hydroxyl groups, and / or the polyester units on the reaction of adipic acid and / or adipic anhydride with diols having an even number are based on CH ₂ groups between the hydroxyl groups, wherein for the preparation of the polyurethane polymer no further isocyanate-reactive compounds in addition to the component C) are used, and wherein the molar ratios of isocyanate groups in A) and / or B to isocyanate-reactive groups in C ) of 0.8: 1.0 to 1.3: 1.0, preferably 0.9: 1.0 to 1.2 : 1.0. Details of the polyurethane polymer including the embodiments have already been described in connection with the device according to the invention. To avoid unnecessary repetition, reference is made to the use thereof.

Uses can be found in a variety of different applications in the electro-mechanical and electro-acoustic field, in particular in the field of energy production from mechanical vibrations (energy harvesting), acoustics, ultrasound, medical diagnostics, acoustic microscopy, mechanical sensors, in particular pressure force and / or strain sensors, robotics and / or communication technology. Typical examples include pressure sensors, electroacoustic transducers, microphones, loudspeakers, vibration transducers, light deflectors, diaphragms, Modulators for optical fiber optics, pyroelectric detectors, capacitors and control systems; and 'intelligent' floors, and systems for converting water wave energy, in particular sea-wave energy, into electrical energy.

Another object of the invention is an electrical and / or electronic device comprising an electromechanical transducer according to the invention.

Examples

Unless otherwise indicated, all percentages are by weight and all analytical measurements are for temperatures of 23 ° C. NCO contents were determined volumetrically in accordance with DIN-EN ISO 11909, unless expressly stated otherwise. The indicated viscosities were determined by means of rotational viscometry according to DIN 53019 at 23 ° C. using a rotational viscometer from Anton Paar Germany GmbH.

The tensile tests were carried out by means of a tractor from Zwick, model number 1455, equipped with a load cell of the total measuring range 1 kN according to DIN 53 504 with a pulling speed of 50 mm / min. S2 specimens were used as specimens. Each measurement was carried out on three identically prepared test specimens and the mean of the data obtained was used for the evaluation. The elongation at break in [%] and the modulus of elasticity in [MPa] at 50% elongation were determined.

The stress relaxation (creep) of the elastomer films was determined on rectangular bars of dimensions 15 mm × 100 mm according to DIN 53 441 at 10% elongation after a time of 30 minutes. The propagation energy was determined according to ASTM D 624-00 at a strain rate of 100 mm / min on rectangular bars of dimensions 15 mm × 100 mm.

The electrical resistance was determined by means of a Keithley Instruments Model No. 6517 A and 8009 laboratory setup in accordance with ASTM D 257 (a method for determining the insulation resistance of materials). Substances used and abbreviations:

Desmodur® N 100: trifunctional biuret based on hexamethylene diisocyanate (HDI biuret), NCO content 21.95 ± 0.3% (according to DIN EN ISO 1 909), viscosity at 23 ° C. 9630 ± 750 mPa · s, Bayer MaterialScience AG, Leverkusen, DE. Desmodur® 44M 4,4'-methylene diphenyl diisocyanate, Bayer MaterialScience AG,

Leverkusen, DE.

Desmodur® XP 2599 Aliphatic, ether group-containing prepolymer based on

HDI, Bayer MaterialScience AG, Leverkusen, DE PolyTHF® 2000 difunctional polytetraethylene glycol polyether with M _n = 2000 g / mol,

BASF SE, Ludwigshafen, DE

Acclaim® 4220 difunctional polypropylene oxide-polyethylene oxide polyether with M _n =

4000 g / mol and a proportion of ethylene oxide units of 20% by weight, Bayer MaterialScience AG, Leverkusen, DE

Acclaim® 6300 trifunctional polypropylene oxide polyether with M _n = 6000 g / mol, Bayer

Material Science AG, Leverkusen, DE

Desmophen® C 1200 Linear, aliphatic polycarbonate polyester, Bayer MaterialScience

AG, Leverkusen, DE. Desmophen® C 2200 Terminal linear aliphatic polycarboxylate ion

Hydroxyl groups and a molecular weight of about 2000 g / mol, Bayer MaterialScience AG, Leverkusen, DE

DBTDL dibutyltin dilaurate, E. Merck KGaA, Darmstadt, DE.

Desmorapid® SO Tin (II) 2-ethylhexanoate, Bayer MaterialScience AG, Leverkusen, DE Irganox® 1076 Octadecyl 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, Ciba

Specialty Chemicals Inc., Basel, CH

The other chemicals were purchased from the chemicals trade (Sigma-Aldrich Chemie GmbH, Taufkirchen, DE).

Example 1: Preparation of a di-isocyanate-functional polyisocyanate prepolymer

592 g of hexamethylene-l, 6-diisocyanate (HDI) and 1.3 g of isophthaloyl chloride were placed in a 4 liter four-necked flask with stirring. Within 2 hours 470 g of Desmophen® C 2201 were added in portions at 80 ° C., followed by stirring at the same temperature for 1 hour. Subsequently, the excess HDI was distilled off by thin-layer distillation at 130 ° C and 0.1 Torr. The NCO prepolymer obtained had an NCO content of 3.4%, it solidified on cooling to room temperature. Example 2: Preparation of a di-isocyanate-functional polyisocyanate prepolymer

To prepare the prepolymer 7.15 kg of Desmodur 44M® were placed in a stirred tank at a temperature of 50 ° C and added 45.85 kg of temperature-controlled polyether Acclaim 6300® within 15 minutes (alternatively, but could also be the polyether at 50 C., and then the isocyanate, likewise heated to 50.degree. C., is added).

Thereafter, the reaction mixture was heated to 100 ° C and held at this temperature for a further 7 hours. After cooling, a product having an NCO content of 2.70 ± 0, lGewichts-% and a viscosity at 70 ° C of about 4200 ± 600 mPas. Example 3 (comparative): Preparation of a polymer not to be used according to the invention

The raw materials used were not degassed separately. 55.2 g of a prepolymer from Example 2 and 33.33 g of PolyTHF® 2000 were mixed with an amount of 0.00083 g of DBTDL in a polypropylene beaker in the Speedmixer at 3000 revolutions per minute for 1 minute. From the still liquid reaction mixture, films of a wet layer thickness of 1 mm were laced by hand on glass plates. All films were dried after production at 80 ° C in a drying oven overnight and then post-annealed at 120 ° C for 5 min. The films could be easily released from the glass plate after tempering by hand.

Example 4 (comparison): Preparation of a polymer not to be used according to the invention The raw materials used were not degassed separately. 50.0 g of Acclaim® 4220 and 0.05 g of Irganox® 1076 were weighed into a polypropylene beaker and mixed in the Speedmixer at 3000 rpm for 1 minute with 0.4 g DBTDL and 5.75 g Desmodur® N 100 mixed. From the still liquid reaction mixture, films of a wet layer thickness of 1 mm were laced by hand on glass plates. All films were dried after production at 80 ° C in a drying oven overnight and then post-annealed at 120 ° C for 5 min. The films could be easily released from the glass plate after tempering by hand.

Example 5 (comparative): Preparation of a polymer not to be used according to the invention The raw materials used were not degassed separately. 29, ll g of Desmodur® XP 2599 and 50.0 g of Desmophen® C 2200 were loaded with 0.045 g of Desmorapid® SO and 0.05 g of Irganox® 1076 in a polypropylene beaker in the Speedmixer at 3000 revolutions per minute for the duration mixed for 1 minute. From the still liquid reaction mixture, films of a wet layer thickness of 1 mm were laced by hand on glass plates. All films were dried after production at 80 ° C in a drying oven overnight and then post-annealed at 120 ° C for 5 min. The films could be easily released from the glass plate after tempering by hand.

Example 6 (Comparative): Preparation of a Polymer Not According to the Invention The raw materials used were not degassed separately. 50.0 g Desmophen® C 1200 was mixed with 0.05 g Irganox® 1076, 9.188 g Desmodur® N100 and 0.013 g DBTDL in a polypropylene beaker in the Speedmixer at 3000 rpm for 1 minute. From the still liquid reaction mixture, films of a wet layer thickness of 1 mm were laced by hand on glass plates. All films were dried after production at 80 ° C in a drying oven overnight and then post-annealed at 120 ° C for 5 min. The films could be easily released from the glass plate after tempering by hand.

Example 7: Preparation of a polymer to be used according to the invention

The raw materials used were not degassed separately. 309.5 g of the prepolymer from Example 1 was preheated to 60 ° C, with 10.0 g of TMP, 0.2 g of DBTDL and 0.01 g Irganox ^® was weighed into a polypropylene beaker 1076 and in the Speedmixer at 3000 revolutions per minute mixed for a period of 1 minute

From the still liquid reaction mixture, films of a wet layer thickness of 1 mm were laced by hand on glass plates. All films were cured after production at 100 ° C in the oven for a period of 1 h. The films could be easily released from the glass plate after curing by hand.

Elongation at break and modulus of elasticity in tension (DIN EN 150 672 1-1), tension relaxation in tension (Creep; DIN 53 441), tensile elongation at break (ASTM D 412), tear strength (ASTM D 624 -00) and the electrical resistance (ASTM D 257) determined. The results for the examples not according to the invention and the examples of polymer elements according to the invention are shown in Table 1 below. Numerical values the volume resistances are given in exponential notation. For example, the numerical value 3 means a volume resistance of 1.88 × 10 ¹² ohm cm.

Breaking modulus Continuing tear propagation

Example Stretching 50% Creep Stretching 100% Strength Widestand

[%] [Mpa] [%] [%] [kN / m] [Ohm cm]

3 (Cf.) 220 1.032 5.01 0.92 0.995 1.88E + 12

4 (Cf.) 133 0.825 2.90 0.65 0.265 9.61E + 10

5 (Cf.) 274 0.874 18.35 16.26 1.421 1.20E + 13

6 (See) 125 1.723 2.35 0.76 0.829 2.42E + 13

7,274 1,785 3.34 1.56 1.746 3.43E + 13

TABLE 1 Properties of the Films Produced in Examples 3 to 6 (Comp. = Comparison) and 7 (Inventive) It was found in the experiments that the polymer according to the invention has a clear advantage over the prior art as a film.

Particularly advantageous when using the film according to the invention is the combination of high elongation at break, low creep, high electrical resistance and high tear propagation resistance. Particularly advantageous electromechanical transducers can be produced with this polymer according to the invention.

Claims

claims

An electromechanical transducer comprising a dielectric elastomer contacted by a first electrode and a second electrode, the dielectric elastomer comprising a polyurethane polymer, characterized in that the polyurethane polymer is obtainable from the reaction of

A) a polyisocyanate and / or B) a polyisocyanate prepolymer with C) a compound having at least two isocyanate-reactive groups, wherein the polyisocyanate prepolymer B) and / or the compound having at least two isocyanate-reactive groups C) polycarbonate and / or polyester Units, wherein the polycarbonate units contain hydroxyl-containing polycarbonate polyols having an even number of CEh groups between the hydroxyl groups, and / or the polyester units on the reaction of adipic acid and / or adipic anhydride with diols having an even number CH ₂ groups between the hydroxyl groups are based, wherein for the preparation of the polyurethane polymer no further isocyanate-reactive compounds in addition to the component C) are used, and wherein the molar ratios of isocyanate groups in A) and / or B to isocyanate-reactive groups in C) from 0.8: 1.0 to 1.3: 1.0.

2. Electromechanical transducer according to claim 1, wherein the polyurethane polymer obtainable from the reaction of a polyisocyanate prepolymer B) with a compound having at least two NCO-reactive groups C).

3. Electromechanical transducer according to claim 2, wherein the polyisocyanate prepolymer

B) is obtainable from the reaction of a diisocyanate A) with a polycarbonate polyol containing an even number of CH ₂ groups, and / or a polyester polyol based on the reaction of adipic acid and / or adipic anhydride with diols having an even number of CH ₂ - Groups.

4. Electromechanical transducer according to claim 2 or 3, characterized in that the polyisocyanate prepolymer B) based on hexamethylene diisocyanate and component

C) is trimethylolpropane. Electromechanical transducer according to one of claims 1 to 4, wherein the polyurethane polymer has a modulus of elasticity at an elongation of 50% of> 0.1 MPa to <15 MPa and a tear strength of greater than 1.5 kN / m.

A method of making an electromechanical transducer comprising the steps of:

1) providing a first electrode and a second electrode;

A) a polyisocyanate and / or B) a polyisocyanate prepolymer with C) a compound having at least two isocyanate-reactive groups, wherein the polyisocyanate prepolymer B) and / or the compound having at least two isocyanate-reactive groups C) polycarbonate and / or polyester Units, wherein the polycarboxylate units contain hydroxyl-containing polycarbonate polyols having an even number of CH 2 groups between the hydroxyl groups, and / or the polyester units on the reaction of adipic acid and / or adipic anhydride with diols which are based on an even number of CH ₂ groups between the hydroxyl groups, wherein for the preparation of the polyurethane polymer, no further isocyanate-reactive compounds in addition to the component C) are used, and wherein the molar ratios of isocyanate groups in A) and / or B to towards isocyanate-reactive groups in C) of 0.8: 1.0 to 1.3: 1.0.

Use of a dielectric elastomer as an actuator, sensor and / or generator in an electromechanical transducer, wherein the dielectric elastomer a Polyurethane polymer, and the polyurethane polymer is obtainable from the reaction of

A) a polyisocyanate and / or B) a polyisocyanate prepolymer with C) a compound having at least two isocyanate-reactive groups, wherein the polyisocyanate prepolymer B) and / or the compound having at least two isocyanate-reactive groups C) polycarbonate and / or polyester Units comprising polycarbonate units containing hydroxyl group-containing polycarbonate polyols having an even number of CEh groups between the hydroxyl groups, and / or the polyester units on the reaction of adipic acid and / or adipic anhydride with diols containing a are just number of CH ₂ groups between the hydroxyl groups based, wherein for the preparation of the polyurethane polymer no further isocyanate-reactive compounds in addition to the component C) are used, and wherein the molar ratios of isocyanate groups in A) and / or B to isocyanate-reactive groups in C) of 0.8: 1.0 to 1.3: 1.0.

Use according to claim 7, wherein the polyurethane polymer obtainable from the reaction of a polyisocyanate prepolymer B) with a compound having at least two NCO-reactive groups C).

Use of a dielectric elastomer according to claim 7 or 8 as an actuator, sensor and / or generator in an electromechanical transducer having a tear strength of greater than 1.5 kN / m.

10. Electrical and / or electronic device comprising an electromechanical transducer according to one of claims 1 to 5.