EP2870189A1 - Method for producing a multilayer dielectric polyurethane film system - Google Patents

Abstract

The present invention relates to a method for producing a multilayer dielectric polyurethane film system comprising the following method steps: I) producing a mixture comprising a) a compound containing isocyanate groups with an isocyanate group content of > 10% by weight and ≤ 50% by weight, b) a compound containing isocyanate reactive groups with an OH number of ≥ 20 and ≤ 150, wherein the sum of the number average functionality of isocyanate groups and of isocyanate reactive groups in compounds a) and b) is ≥ 2.6 and ≤ 6, II) applying the mixture immediately after it has been produced to a substrate in the form of a wet film, III) curing said wet film while forming the polyurethane film and IV) applying an electrode layer on the almost completely dried film, V) repeating steps I)-IV) to generate a multilayer system. The invention further relates to a multilayer dielectric polyurethane film system and an electromechanical transducer.

Description

 Method for producing a multilayer dielectric polyurethane film system

The present invention relates to a process for producing a multi-layered electroactive polymer film system comprising layers of dielectric polyurethane and conductive electrode layer having a multi-layer actuator / multilayer actuator structure particularly suitable for use in electromechanical transducers. Further objects of the invention are a dielectric polyurethane film system obtainable by the process according to the invention and an electromechanical transducer obtainable by this process.

Transducers - also called electromechanical transducers - convert electrical energy into mechanical energy and vice versa. They can be used as part of sensors, actuators and / or generators.

The basic structure of such a transducer consists of electroactive polymers (EAP). The construction principle and the operation are similar to those of an electrical capacitor. Between two conductive plates, to which a voltage is applied, there is a dielectric. However, EAPs are a ductile dielectric that deforms in the electric field. Strictly speaking, dielectric elastomers are mostly in the form of films (DEAP, dielectric electroactive polymer) which have a high electrical resistance and are coated on both sides with high conductivity, stretchable electrodes (electrode), as described for example in WO-A 01/006575. This basic structure can be used in a variety of configurations for the production of sensors, actuators or generators. In addition to single-layered structures, multi-layered structures are also known.

Depending on the application, electroactive polymers as elastic dielectrics in transducer systems must be divided into different components: Actuators / sensors or generators - different

Have properties. Common electrical properties are: a high electrical resistance of the dielectric, a high dielectric strength, and a high dielectric constant in the frequency range of the application. These properties allow to permanently store a large amount of electrical energy in the volume filled with the electroactive polymer.

Common mechanical properties are sufficiently high elongation at break, low elongation and sufficiently high compressive / tensile strength. These properties provide a sufficiently large elastic deformability without mechanical damage to the energy converter. For energy converters operating "in train", ie in operation on train It is particularly important that these elastomers have no permanent elongation (flow or "creep" should not occur, otherwise there will be no EAP effect after a certain number of cycles of strains) and no stress relaxation under mechanical load However, there are also different requirements depending on the application: For actuators in the tensile mode, highly reversible stretch elastomers with high elongation at break and low tensile modulus of elasticity are required, whereas for stretched generators a high tensile modulus is useful The requirements for the internal resistance are also different, generators are subject to much higher internal resistance requirements than for actuators.For the literature it is known for actuators that the ductility extensibility is proportional to the dielectric constant and the applied voltage squared and inversely proportional to the modulus : with the relative permittivity s _r , the rigidity t Y and the film thickness d with the switching voltage U shows the elongation _z according to the equation

(with the absolute permittivity ε ₀ )

The voltage in turn depends on the breakdown field strength, ie if the breakdown rupture field strength is very low, no high voltage can be applied. Since this value is squared in the equation for calculating the strain caused by the electrostatic attraction of the electrodes, the breakdown field strength must be correspondingly high. A typical equation can be found in the book by Federico Carpi, Dielectric Elastomers as Electromechanical Transducers, Elsevier, page 314, Equation 30.1, as well as similarly in R. Peirine, Science 287, 5454, 2000, page 837, Equation 2. Equation The previous section makes a very important for the operation of dielectric elastomer actuators property: The smaller the layer thickness zo, the smaller the operating voltage of the actuators can be. At the same time, the layer thickness also shrinks the deformation amplitude. A solution to this dilemma was already presented by PELRINE et al. In an early publication from 1997: individual layers can be stacked on top of each other like piezoelectric stack actuators [RE PELRINE, R. KORNBLUH, JP JOSEPH and S. CHIBA. "Electrostriction of polymer films for microactuators. "In: Micro Electro Mechanical Systems, 1997. ME MS '97, Proceedings, IEEE., Tenth Annual International Workshop on (1997), pp. 238-243.] These layers are electrically connected in parallel, ie above each layer In spite of the low operating voltage U, a relatively high field strength E is applied, whereas mechanically the actuator layers are connected in series, which add individual deformations yourself. The stack demonstrated by PELRINE et al. Had four layers of dielectric and electrode and was made manually. It is important that the electrode layers have a structure. This can be achieved by a spray mask, the inkjet printing or a screen in the case of screen printing. Since then, this idea has been taken up several times and further developed. A major challenge in the production of a stack actuator in all processes is the failure and contamination-free covering of a plurality of dielectric layers and electrodes. CARPI et al. Identified the cutting of a hose as a solution to this problem. The dielectric is in the form of a silicone tube. This tube is cut in a spiral, then the cut surfaces are covered with conductive material, which serve as electrodes [F. CARPI, A. MIGLIORE, G. SERRA and D. DE ROSSI "Helical dielectric elastomer actuators" In: Smart Materials and Structures 14.6 (2005), pp. 1210-1216 CHUC et al Principle on the folding according to CARPI is based [N. I I. CHUC, JK PARK, DV THUY, I IS KIM, JC KCX), inter alia, "Multi-stacked artificial muscle actuator based on synthetic elastomer". In: Proceedings of the 2007 IEEE / RSJ International Conference on Intelligent Robots and Systems San Diego, Calif., USA, Oct. 29 - Nov. 2, 2007 (2007), p. 771.]. However, the dielectric films are each folded only once. The pile actuators from CARPI et al. And CHUC et al. Are not designed to absorb tensile forces. Since the electrostatic forces extend only from outside to outside of adjacent electrodes, there is a risk of delamination of the stack actuators, since there are no forces within the electrodes. KOVACS and DÜRING developed a technique for producing extremely thin soot layers. Thus prepared electrodes should consist of only one layer of primary particles. Such a monolayer builds up electrostatic forces to both adjacent electrodes and thereby is able to absorb tensile forces [G. KOVACS and L. DÜRING. Electroactive Polymer Actuators and Devices (EAP AD) 2009. Edited by Y. BARCOHEN and T. WALLMERSPERGER, Vol. 7287. 1. San Diego, CA, USA: "Contractive tension force stack actuator based on soft dielectric EAP". SPIE, 2009, 72870A 15. j. The previously presented stacking actuator concepts from CARPI et al., CHUC et al., KOVACS and DÜRING have in common that they are designed as actuators with large deflections and for the generation of high forces.All of these basic configurations are based on stack actuators In a 3D multilayer structure, the most efficient conversion of electrical input energy into mechanical work is due to the constructively achieved parallelism between the electric field and the strain direction.The presently available actuators, however, have three major drawbacks due to insufficiently matched elastomer, insufficient F production technology and insufficient long-term stability It is a common feature of all the processes mentioned that the layers adhere only weakly and the layer allied is not monolithic. Thus, the layers can often be disassembled after less than 100 load cycles, ie a delamination of the layers takes place. Also, such methods for polyurethane are still unknown. The object of the invention was to produce monolithic multilayer films without boundary layers, so that no delamination and separation of the layers is possible.

Until now known actuators are either too low in the dielectric constant and / or the breakdown field strength or too high in the module. A disadvantage of known solutions is also the low electrical resistance, which leads to high leakage currents in actuators and in the worst case to an electrical breakdown. In order to achieve high deflections in actuators, these actuators must be constructed according to the equation multi-layered.

For generators, it is important that they produce a high electrical current yield with low losses. Typical losses occur at interfaces, loading and unloading of the dielectric elastomer, and leakage through the dielectric elastomer. In addition, the resistance of the electrically conductive electrode layer of the EAP causes a loss of energy; The electrode should therefore again have the lowest possible electrical resistance. A description can be found in an article by Christian Graf and Jürgen Maas, Energy harvesting cycles based on electroactive polymers, proceedings of SPIE Smart structures, 2010, vol. 7642, 764217. From the derivations of Equations 34 and 35, it follows on page 9 (12), last sentence, that the energy loss is minimal when the dielectric constant as well as the electrical resistance are particularly high. Since almost all electroactive polymers are operated under cyclic loading and pre-stretched structures, the materials, as mentioned, are not allowed to flow at repeated cyclic loads and the "creep" should be as low as possible.

In the prior art, transducers which contain various polymers as a constituent of the electroactive layer are described, for example, in WO-A 01/006575, and processes for their preparation are described.

DE 10 2007 005 960 describes soot-filled polyether-based polyurethanes. A disadvantage of this invention is the very low electrical resistance of the DEAP film, so that the loss due to heat is too high.

WO 2010/049079 describes one-component polyurethane systems in organic solvents. The disadvantage here is that only low degrees of branching can be used, so that the systems have too high a creep under cyclic tensile loads Functionality of 2 and smaller possible, so that even the systems known from DE 10 2007 059 858 do not meet the requirements. A one-component solution of higher functionality (in organic or aqueous solvents / dispersion) would lead to a gel or powder, with infinite molecular weight, which makes coating / film formation no longer possible. At the same time, due to the linearity, a reversible tensile-strain process, as it must be used in EAPs, not possible because it leads to a flow of the polymer Furthermore, the electrical resistance of the described polyether is too low.

EP 2 280 034 describes polyether polyols which have too low electrical resistance.

E 2 0649 describes various approaches. Both the tensile strengths and the electrical resistances as well as the breakdown field strength are too low to arrive at technically relevant, high efficiencies.

WO 2010012389 describes amine-crosslinked isocyanates, but here too the electrical resistance and the breakdown field strength are too low.

In all of the methods described in the prior art is disadvantageous that no multilayer actuators can be produced based on polyurethane, since the layers in separate production by a roll-to-roll process no longer strong enough adhere to each other and delamini eren.

It was therefore an object of the present invention to provide a continuous process with which multi-player systems, i. Layer systems of arranged in alternating order dielectric polyurethane films and electrode layers, can be obtained. The multi-layer actuators obtainable from this should have a very high returnability, furthermore they do not tend to flow and have a high electrical resistance.

In particular, the polyurethane process polyurethane film systems which can be produced by the process should have one or more of the following properties: A: For actuators operated in tension mode: a) A tensile strength of> 2 MPa, more preferably> 4, especially> 5 according to DIN 53 504 b ) An elongation at break of> 200% according to DIN 53 504 c) A stress relaxation (Creep) at 10% deformation after 30 minutes according to DIN 53 441 of <30% (particularly preferred <20, very particularly <10%) B: For all actuators d) A stress relaxation (creep) at 10% deformation after 30 min according to DIN 53 441 of <

30% (particularly preferred <20, e) A breakdown field strength of> 40 V / μιη according to ASTM D 149-97a (particularly preferably> 60, very particularly preferably> 80) f) An electrical resistance of> 1.5E12 ohm m according to ASTM D 257 (particularly preferably>

2E12 ohm m, especially,> 5 El 2 ohm m, especially> 1E13 ohm m). g) A permanent elongation at 50% elongation after DI 53 504 of <3% h) A dielectric constant of> 5 at 0.01 - 1 Hz according to ASTM D 150-98 i) One layer thickness of a dielectric film (calculated as monolayer) < 1000 μιη j) wherein the system preferably consists of> 50 and <10000 layers k) and the layers adhere indestructible to each other.

The object according to the invention is achieved by a method for producing a multilayer dielectric polyurethane film system (multilayer) in which at least the following steps are carried out:

FI prepare a mixture comprising a) a compound containing isocyanate groups

Isocyanate groups of> 10% by weight and <50% by weight b) an isocyanate-reactive group-containing compound having an Ol I number of> 20 and <150, wherein the sum of the number average functionality of isocyanate groups and

Isocyanate-reactive groups of compounds a) and b)> 2.6 and <6,

II) Applying the mixture immediately after its preparation in the form of a

Wet film on a support,

III) curing of the wet film is to form the polyurethane film and IV) applying a, in particular structured, electrode layer to the almost completely dried film, in particular by spraying, pouring, knife coating, inkjet or the like, wherein the electrode optionally contains a binder and is optionally dried,

V) repeating steps I) -IV), preferably> 2 and <1,000,000 times, more preferably> 5 and <100,000 and especially preferably> 10 and <10,000, with very particular preference> 10 and <5,000 and in particular very particularly preferably> 20 and <

1000th

The multilayer film produced by the process according to the invention has good mechanical strength and high elasticity. Furthermore, it has good electrical properties such as a high breakdown field strength, a high electrical resistance and a high dielectric constant and can therefore be used advantageously in a elektr omechanis Chen converter with high efficiency.

According to the invention, the layers are produced in stacks, so that preferably each layer is just dry in order to prevent the next layer from flowing into the lower layer, but is still so sticky that an indestructible adhesion is present, which ideally still contains a chemical after-reaction , The 100% conversion of a coated layer is thus preferably carried out only by the drying, which experience the subsequent stories. This results in a monolithic layer structure without delamination of the layers.

The greatest advantage of the chemical process according to the invention is the strong adhesive and adhesive force of the polyurethane to the electrode layer, but especially the resulting monolithic structure with the lower polyurethane layer, in the case of a structured electrode surface which is smaller than the polyurethane surface. The main disadvantage of a mechanical stacking process in comparison with this is that it always always first before application, the release film of the film must be removed. 1 Lierbei it comes to stretching of the film, which usually throws wrinkles or even breaks and in any case changes the structure under strain. As a result, it is mechanically impossible to add a layer exactly to the next layer so that, in the case of a construction with a high number of layers, in the worst case, there will be such a strong slippage that electrical breakdown occurs. But even small dislocations lead to a loss of the actuarial field of action. Particularly disadvantageous and sometimes not possible is therefore the production of small structures, so that the mechanical Production is only suitable for large structures. Another disadvantage is that the mechanical steps are all downstream, and thus less productive with conventional manufacturing technology.

With the help of suitable masks, the chemical process can be used not only to structure layers in the manufacturing process, but also to precisely stack and process them one to one. The adhesion of the polyurethane (which is generally higher than silicone) is higher due to the chemical process. Also, the process according to the invention has only one carrier on the lowest layer, so that it is only removed in the final step in the finalization of all layers and thus no strain is previously present. In other words: After the first layer has been formed on the support, the optionally structured electrode layer applied to the almost completely dried film serves as support for the next polyurethane film, so that successively a layer stack [PU layer electrode] with n = 2 , 3, 4, ... arises. Individual polyurethane layers of different thicknesses are possible in the coating: [(polyurethane layer of a first thickness) - (electrode)] - [(polyurethane layer of a second thickness) - (electrode)] - etc ..

Another advantage is that the layer thicknesses that are produced can be significantly lower. This is because with the mechanical variant, the layers always have to be removed from the carrier and thus tear with thin layers. This disadvantage is not given in the inventive method. Productivity is significantly higher due to the lack of robots to remove layers, and more accessible by today's carousel technology.

According to the invention, for example, 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 (1112-MDI) or their mixtures of any desired isomer, 1, 4-cyclohexylene diisocyanate, 4-isocyanatomethyl-l, 8-octane diisocyanate (nonane triisocyanate), 1, 4-phenylene diisocyanate, 2,4- and / or 2, 6-T oluylene diisocyanate (TDI), 1, 5-naphthylene diisocyanate, 2,2'- and / or 2,4'- and / or 4,4'-diphenylmethane diisocyanate (MDI), 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 diisocyanate) having alkyl groups with 1 to 8 carbon atoms and mixtures thereof. Furthermore, modifications such as allophanate, uretdione, urethane, isocyanurate, biuret. Iminooxadiazindion- or Oxadiazintrionstruktur containing compounds based on said diisocyanates suitable building blocks of component a) and polynuclear compounds such as polymeric MDI (pMDI) and combinations of all. Preferred are modifications having a functionality of from 2 to 6, preferably from 2.0 to 4.5 and more preferably from 2.6 to 4.2, and most preferably from 2.8 to 4.0 and most preferably from 2.8 used to 3.8. Diisocyanates from the series HDI, IPDI, H12-MDI, TDI and MDI are particularly preferably used for the modification. Particular preference is given to HDI. Very particular preference is given to using an HDI-based polyisocyanate having a functionality of> 2.6. Biurets, allophanates, isocyanurates and also Iminooxadiazindion- or Oxadiazintrionstruktur are particularly preferably used, very particularly preferred biurets. The preferred NGO content is> 10% by weight, more preferably> 15% and most preferably> 18% by weight. The NGO content is <= 50 wt .-%, preferably <40 wt .-% very particularly preferably <35 wt .-%, very particularly preferably <30 wt .-% and most preferably <25 wt .-%. The NGO content is particularly preferably between 18 and 25% by weight. Very particular preference is given to using as a) modified aliphatic isocyanates based on HDI with a free, unreacted monomeric fraction of free isocyanate of <0.5% by weight.

According to a preferred embodiment, it is provided that the compound a) has a number-average functionality of isocyanate groups of> 2.0 and <4.

In particular, it is also advantageous if the compound a) comprises or consists of an aliphatic polyisocyanate, preferably hexamethylene diisocyanate and particularly preferably a biuret and / or isocyanurate of hexamethylene diisocyanate.

According to the prior art, the isocyanate groups may also be blocked partially or completely until their reaction with the isocyanate-reactive groups, so that they can not react directly with the isocyanate-reactive group. This ensures that the reaction takes place only at a certain temperature (blocking temperature). Typical blocking agents are found in the prior art and are selected so that they split off at temperatures between 60 and 220 ° C, depending on the substance, again from the isocyanate group and only then react with the isocyanate-reactive group. There are blocking agents which are incorporated into the polyurethane and also those which remain in the polyurethane as a solvent or plasticizer or outgas from the polyurethane. One also speaks of blocked NGO values. If the invention refers to NGO values, this is always related to the unblocked NGO value. Usually, up to <0.5% Blocki tert. Typical blocking agents are, for example, caprolactam, methyl ethyl ketoxime, pyrazoles such as 3,5-dimethyl-3, 2-pyrazole or 1, pyrazole, triazoles such as 1, 2,4-triazole , Diisopropylamine, diethylmalonate, diethylmain, phenol or its derivatives or imidazole.

The isocyanate-reactive groups of compound b) are functional groups which can react to form covalent bonds with isocyanate groups. In particular, these may be amine, epoxy, hydroxyl, thiol, mercapto, acrylic, anhydride, vinyl, and / or carbinol Act groups. The isocyanate-reactive groups are particularly preferably hydroxyl and / or amine groups.

It is advantageous if the compound b) has a number-average functionality of isocyanate-reactive groups of> 2.0 and <4, wherein the isocyanate-reactive groups are preferably hydroxy and / or amine.

The compound b) may preferably have an OH number> 27 and <150, more preferably> 27 and <120 mg OH / g.

The average functionality of an isocyanate-reactive group in b) can be from 1.5 to 6, preferably from 1.8 to 4 and particularly preferably from 1.8 to 3. The number average molecular weight of b) can be 1000-8000 g mol, preferably from 1500-4000 g / mol and more preferably from 1500-3000 g / mol.

It is also preferred if the isocyanate-reactive groups of the compound b) is a polymer.

According to an advantageous embodiment of the method according to the invention, it is provided that the compound b) is a diol and particularly preferably a polyester diol and / or a diol

Polycarbonate diol comprises or consists of.

Compound b) may contain polyether polyols, polyether amines, polyetherester polyols, polycarbonate polyols, polyethercarbonate polyols, polyester polyols, polybutadiene derivatives,

Polysiloxanes based derivatives and mixtures thereof are used. However, b) preferably comprises or consists of a polyol having at least two isocyanate-reactive hydroxyl groups. Very particular preference is given to b) polyether, polyester, polycarbonate and polyetheresterpolyols, polybutadiene polyols, polysiloxane polyols, particularly preferably polybutadienols, polysiloxane polyols, polyester polyols and / or polycarbonate polyols, very particularly preferably polyester polyols and / or polycarbonate polyols. Suitable polyester polyols may be polycondensates of di- and optionally tri- and tetraols and di- and optionally tri- and tetracarboxylic acids or hydroxy carb ons 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 are prepared in a manner known per se by polycondensation from aliphatic and / or aromatic polycarboxylic acids having 4 to 16 carbon atoms, optionally from their anhydrides and optionally from their low molecular weight esters, including R 2, predominantly low molecular weight polyols having 2 as reaction components to 12 carbon atoms are used. Examples of suitable alcohols are ethylene glycol, butylene glycol, diethylene glycol, triethylene glycol, polyalkylene glycols, such as polyethylene glycol, and also 1,2-propanediol. 1, 3-propanediol, butanediol (1,3), butanediol (1,4), hexanediol (1,6) and isomers, neopentyl glycol or hydroxypivalic acid neopentyl glycol ester or mixtures thereof, wherein hexanediol (1,6) and isomers, butanediol (I, 4), N epe nty lgl yk ol and hydropexpivalic acid neopentyl glycol esters are preferred. In addition, it is also possible to use polyols, such as trimethylolpropane, glycerol, erythritol, pentachloride, trimethylolbenzene or trishydroxyethyl isocyanurate or mixtures thereof. Diols are particularly preferably used, very particular preference is given to butanediol (1,4) and hexanediol (1,6), very particular preference to hexanediol (1,6). Examples of dicarboxylic acids which may be mentioned are phthalic acid, isophthalic acid, terephthalic acid, tetrahydrate, hexahydrophthalic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid, sebacic acid, glutaric acid, tetrachlorophthalic acid, maleic acid, fumaric acid, itaconic acid, malonic acid, succinic acid, 2-methylsuccinic acid, 3, 3 Diethylglutar s äur e and / or 2,2-Dirnethylbemsteinsäure be used. The acid source used may also be the corresponding anhydrides.

It is also possible to use monocarboxylic acids, such as benzoic acid and hexanecarboxylic acid.

Preferred acids are aliphatic or aromatic acids of the abovementioned type. Particularly preferred are adipic acid, isophthalic acid and phthalic acid, most preferably isophthalic acid and phthalic acid.

Hydrooxycarboxylic acids which can be used as reactants in the preparation of a polyesterpolyol having terminal hydroxyl groups are, for example, hydroxycaproic acid, hydroxy oxybutric acid, hydroxydecic acid or hydroxy stearic acid or mixtures thereof. Suitable lactones are caprolactone, butyrolactone or homologs of the mixtures thereof. Preference is given to caprolactone. Very particular preference is given to using polyesterdiols, very particularly preferably based on reaction products of adipic acid, isophthalic acid and phthalic acid with butanediol (1,4) and hexanediol (1,6).

Hydroxyl-containing polycarbonates, for example polycarbonate polyols, preferably polycarbonate diols, can be used as isocyanate-reactive group-containing compound b). These can be obtained by reaction of carbonic acid derivatives such as diphenyl carbonate, dimethyl carbonate or phosgene by means of polycondensation with polyols, preferably diols.

Examples of suitable diols are ethylene glycol, 1,2- and 1,3-propanediol, 1,3- and 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, 1, 4-bishydroxymethylcyclohexane, 2-methyl - 1, 3 -propanediol, 2,2,4-trimethylpentanediol-l, 3, dipropylene glycol, polypropylene glycols, dibutylene glycol, polybutylene glycols, bisphenol A, 1.10-decanediol. 1,12-Dodecanediol or lactone-modified diols of the type mentioned above or mixtures thereof.

Preferably, the diol component contains from 40 percent by weight to 100 percent by weight of hexanediol, preferably 1,6-hexanediol and or hexanediol derivatives. Such hexanediol derivatives are based on hexanediol and may have ester or ether groups in addition to terminal Ol I groups. Such derivatives are obtainable, for example, by reaction of hexanediol with excess caprolactone or by etherification of hexanediol with itself to give di- or trihexylenglycol. The amount of these and other components are chosen in the present invention in a known manner such that the sum does not exceed 100 weight percent, in particular 100 weight percent results.

Hydroxyl-containing polycarbonates, especially polycarbonate polyols, are preferably linearly constructed. Particular preference is given to using a polycarboxylate ondiol based on 1,6-hexanediol.

Also, although less preferred, in b) polyether polyols can be used. For example, polytetramethylene glycol polyethers as obtainable by polymerization of tetrahydrofuran by means of cationic ring opening are suitable. Also suitable polyether polyols may be the addition products of styrene oxide, ethylene oxide, propylene oxide, butylene oxide and / or epichlorohydrin to di- or polyfunctional starter molecules. Examples of suitable starter molecules which may be used are water, butyldiglycol, glycerol, diethylene glycol, trimethylolpropane, propylene glycol, sorbitol, ethylenediamine, triethanolamine or 1,4-butanediol or mixtures thereof. Hydroxy-functional oligobutadiene, hydrogenated hydroxy-functional oligobutadiene, hydroxy-functional siloxanes, glycerol or TMP monoallyl ethers can also be used alone or in any desired mixture.

Furthermore, polyether polyols can be prepared by alkaline catalysis or by double metal cyanide catalysis or optionally in stepwise reaction by alkaline catalysis and Dopp elmetallcy anidkataly s e of a starter molecule and epoxides, preferably ethylene and / or propylene oxide and have terminal hydroxyl groups. A description of double metalloid catalyzed catalysts (DMC catalysis) can be found, for example, in US Pat. No. 5,158,922 and in published patent application E 0 654 302 A I. Suitable starters are the compounds with hydroxyl and / or amino groups known to those skilled in the art, as well as water. The functionality of the starter is at least 2 and at most 6. Of course, mixtures of multiple starters can be used. Furthermore, mixtures of several polyether polyols can be used as polyether polyols. Suitable compounds b) are also ester diols such as a-hydroxybutyl-e-hydroxy-caproic acid ester, ro-hydroxyhexyl-y-hydroxybutyric acid ester, adipic acid (.beta.-hydroxyethyl) ester or

Terephthalic acid bis (.beta.-hydroxyethyl) ester.

Furthermore, monofunctional compounds can also be used in step I). Examples of such monofunctional compounds are ethanol, n-butanol, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, dipropylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether,

Tripropylene glycol monobutyl ether, 2-ethylhexanol, 1-octanol, 1-dodecanol or 1-hexadecanol or mixtures thereof. Less preferably, chain extenders or crosslinking agents of compound b) may be added proportionately in step I). In this case, compounds having a functionality of 2 to 3 and a molecular weight of 62 to 500 are preferably used. It may be aromatic or aliphatic amine chain extender such as diethyl toluene diamine (DETDA), ^3,3, dichloro-4,4'-diamino-diphenyimethan (MBOCA), 3,5-diamino-4-chloro- isobutyl, 4-methyl 2,6-bis (methylthio) -1,3-diaminobenzene (Ethacure 300), trimethylene glycol di-p-aminobenzoate (Polacure 740M) and 4,4'-diamino-2,2'-dioro-5,5 '-diethyldiphenylmethane (MCDEA) can be used. Particularly preferred are MBOCA and 3,5-diamino 4-chloro-isobutylbenzoate Components suitable for chain extension 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 Methylpentamethylenediamine, diethylenetriamine, diaminodicyclohexylmethane or dimethylethylenediamine or mixtures thereof.

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), also Ol [groups. 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, and alkanolamines, such as N-aminoethylethanolamine , Ethanolamine, 3-aminopropanol, neopentanolamine. To chain terminations 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 N, N-dimethylaminopropylamine.

Often these have a thixotropic effect due to their high reactivity, so that the rheology is changed so that the mixture has a higher viscosity on the substrate. Examples of non-aminic chain extenders which are often used are, for example, 2,2'-thiodiethanol, 1,2-propanediol, 1,3-propanediol, glycerol, 2,3-butanediol, 1,3-butanediol, 1,4-butanediol, 2-methylpropanediol 1,3, pentanediol-1,2, pentanediol-1,3, pentanediol-1,4, pentanediol-1,5, 2,2-dimethyl-1,2-propanediol, 2-methylbutanediol-1, 4, 2- Methylbutanediol-1,3,1,1,1-trimethylolethane, 3-methyl-l, 5-pentanediol, 1,1,1-trimethylolpropane, 1,6-hexanediol, 1,7-heptanediol, 2-ethyl-1, 6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol 1,11-undecanediol, 1,12-dodecanediol, diethylene glycol, triethylene glycol, 1,4-cyclohexanediol, 1,3-cyclohexanediol and water used.

Most preferably, a) and b) have low levels of free water, residual acids and metal contents. The residual water content of b) is preferably <1% by weight, more preferably <0.7% by weight (based on b)). The residual acid content of b) is preferably <1% by weight, more preferably <0.7% by weight (based on B). The residual metal contents, caused, for example, by residues of catalyst constituents used in the preparation of the educts, should preferably be less than 1000 ppm and more preferably less than 500 ppm, based on a) or b). The ratio of isocyanate-reactive groups to isocyanate groups in the mixture of step I) can be from 1: 3 to 3: 1, preferably from 1: 1.5 to 1.5: 1, more preferably from 1: 1.3 to 1, 3: 1 and most preferably from 1: 1.02 to 1: 0.95.

In addition to compounds a) and b), the mixture of step I) may additionally contain auxiliaries and additives. Examples of such auxiliaries and additives are crosslinkers, thickeners, solvents, thixotropic agents, stabilizers, antioxidants, light stabilizers, emulsifiers, surfactants, adhesives, plasticizers, water repellents, pigments, fillers rheology improvers, plasticizers, degassing and defoaming agents, wetting additives and catalysts and fillers. The mixture of step I) particularly preferably contains wetting additives. Usually, the wetting additive is contained in an amount of 0.05 to 1.0% by weight in the mixture. Typical wetting additives are available, for example, from Altana (Byk additives such as: polyester-modified polydimethylsiloxane, polyether-modified polydimethylsiloxane or acrylate copolymeric polymers, and, for example, C6F13 fluorotelomers). Preferably, the mixture of step I) comprises fillers having a high dielectric constant. 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, poly-3-hexythiophene. By adding the filler, the dielectric constant of the polyurethane film can be increased.

In addition, a higher dielectric constant can also be achieved by introducing electrically conductive fillers below the percolation threshold. Examples of such materials are carbon black, graphite, graphene, fibers, 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.

In the context of the present invention, additives for increasing the dielectric constant and / or the electrical breakdown field strength can also be added after the film formation in steps II) and III). This can be achieved, for example, by producing one or more further layers or by penetrating the polyurethane film, for example by

Diffuse done. As the solvent, aqueous and organic solvents can be used.

Preferably, a solvent may be used which has a vapor pressure at 20 ° C of>

0, 1 mbar and <200 mbar, preferably> 0.2 mbar and <150 mbar and particularly preferably> 0.3 mbar and <120 mbar. This solvent may in particular be added to the mixture of step I). It is particularly advantageous that the films of the invention can be prepared on a roll coating device.

The polyurethane film may have a layer thickness of 0.1 μm to 1000 μm, preferably from 1 μm to 500 μm, more preferably from 5 μm to 200 μm, and very particularly preferably from 10 μm to 100 μm. The application of the mixture of step I) to the carrier in step II) can be carried out, for example, by knife coating, brushing, pouring, spinning, spraying, extrusion in a batch process, i. in a repetitive process with coating steps and intervening drying steps. Preferably, the mixture is applied to the carrier with a squeegee (such as a squeegee, quark, or the like), rollers (such as anilox rollers, gravure rollers, burnishing rollers, or the like) or a nozzle. The nozzle may be part of a nozzle application. It is also possible to operate several commissioned works simultaneously or in succession. Several layers can be applied simultaneously with a commissioned work. Preferably, a nozzle is used, and more preferably a residence time optimized and / or recirculation-free nozzle. Most preferably, the distance of the nozzle to the carrier is less than three times the thickness of the wet film, preferably less than twice the thickness of the wet film and more preferably less than one and a half times the thickness of the wet film. If, for example, 150 μm wet film is coated (if the wet film contains 20% by weight of solvent, this corresponds to 120 μm of cured film), then the distance between the nozzle and the substrate should be <300 μm. If the distance of the nozzle to the support is chosen as described above, a roller coater can be used to make the films.

According to a further preferred embodiment of the method according to the invention, in step II) a wet film having a thickness of from 10 to 300 μm, preferably from 10 to 300 μm, may be used. 5 to 150 μηι, more preferably from 20 to 120 μηι and very particularly preferably from 20 to 80 μηι is produced.

It is also preferred if the wet film is cured in step III) by being passed through a first drying section, which preferably has a temperature> 40 ° C and <120 ° C, more preferably> 60 ° C and <1 10 ° C and particularly preferably> 60 ° C and <100 ° C. The wet film may also be passed through a second drying section after the first drying section, which preferably has a temperature> 60 ° C and <130 ° C, more preferably> 80 ° C and <ί 20 ° C and particularly preferably> 90 ° C and <120 ° C has.

In addition, after the second drying section, the wet film can also be passed through a third drying section, which preferably has a temperature> 110 ° C. and <180 ° C., more preferably> 110 ° C. and <150 ° C. and particularly preferably> 110 ° C. and <140 ° C.

Drying can be done in suspension or in roller dryers, such as those from Kröner !. Coatema, Drytec or Polytype offered on the market. Alternatively, infrared or UV curing / drying can be used. The typical speed at which the wet film is carried on the carrier through the drying section (s) is> 0.5 m / min and <600 mmin, more preferably> 0.5 m / min and <500 m / min and more preferably> 0.5 m / min and <100 m / min.

The dry section length and the supply air of the dry sections are adapted to the speed. Most commonly, the total residence time of the wet film in the dry section (s) is> 10 seconds and <60 minutes, preferably> 30 seconds and <40

Minutes, more preferably> 40 seconds and <30 minutes and most preferably> 40 seconds and <10 minutes.

The dielectric polyurethane film according to the invention is provided with a further conductive layer according to method IV. This can be done on one side or on both sides, in one layer or in several layers one above the other, by complete or by surface partial coating. The coating can be full-surface or structured or segmented, i. take place only in subregions of the surface of the underlying layer, with a specifiable geometrical structure.

Glass, release paper, films and plastics, from which the produced polyurethane dielectric film can be easily separated, are particularly suitable as carriers for the production of a polymer film from the reaction mixture. Particularly preferred paper or films are used. Paper can be coated on one or both sides, for example, with silicone or plastics. The coating and / or the film can be made, for example, of plastics such as polyethylene, polypropylene, polymethylpentene, polyethylene terephthalate, polypropylene, polyethylene, polyvinyl chloride, Teflon, polystyrene, polybutadiene, polyurethane, acrylic ester-styrene-acrylonitrile, acrylonitrile / butadiene / acrylate, acrylonitrile il-butadiene styrene, acrylonitrile / chlorinated polyethylene / styrene, acrylonitrile / methyl methacrylate, butadiene rubber, butyl chut chuk, casein plastics, Artificial horn, cellulose acetate, cellulose hydrate, cellulose nitrate, chloroprene rubber, chitin, chitosan, cyclo-olefin copolymers, epoxy resin, ethylene-ethyl acrylate copolymer, ethylene-propylene copolymer, ethylene-propylene-diene rubber, ethylene-vinyl acetate, fluororubber, urea Formaldehyde resin, isoprene rubber, lignin, melamine-formaldehyde resin, melamine / phenol-formaldehyde, methyl acrylate / butadiene / styrene, Naturkauts chuk (gum arabic), phenol formaidebyd resin, perfluoroalkoxylalkane, polyacrylonitrile, polyamide, polybutylene succinate, polybutylene terephthalate, polycaprolactone, polycarbonate , Polycblortrifluoroethylene, polyesters, polyester amide, polyether block amide, polyetherimide, polyether ketones, polyethersulfone, polyhydroxyalkanoates, polyhydroxybutyrate, polyimide, polyisobutylene, polylactide (polylactic acid), polymethacrylmethylimide, polymethylene terephthalate, polymethyl methacrylate, polymethylpentene, polyoxymethylene or polyacetal, polyphenylene ether, Polyphenylene sulfide, polyphthalam id, polypyrrole, polystyrene, polysulfone, polytetrafluoroethylene, polyurethane PUR, polyvinyl acetate, polyvinyl butyral, polyvinyl chloride, polyvinylidene fluoride, polyvinylpyrrolidone, silicone, styrene-acrylonitrile copolymer, styrene-butadiene rubber, styrene-butadiene-styrene, thermoplastic starch, thermoplastic polyurethane, Vinyl chloride / ethylene, vinyl chloride / ethylene / methacrylate. Alternatively, these plastics can also be used directly as support materials and / or additionally provided with further internal or external release agents or layers. The layers may have barrier functions or may also contain conductive structures which may optionally be transferred to the polyurethane dielectric film. The plastics may be axially or biaxially oriented or stretched and may be pretreated by pressure or corona. The films can also be reinforced. Typical reinforcements are fabrics such as textile or glass fibers.

According to a particularly preferred embodiment, a carrier made of glass, plastic or paper and preferably made of silicone or plastic-coated paper can be used. The film or paper can be peeled off directly after coating and reused. In a particular embodiment, the film can be moved in a circle and the dielectric polyurethane film can be transferred directly to a new carrier when it is peeled off. In a preferred embodiment, the carrier is provided with a structure. In the same way one speaks of a coinage. The embossment is such that the structure transfers to the polyurethane dielectric film in such a manner that the embossment is formed only in the surface of the polyurethane dielectric film. The embossing is smooth when the film is stretched. The embossment is made such that an electrode layer on the film is stretched when stretched without significantly stretching that layer itself. The embossment is preferably embossed in a roll-to-roll process in the carrier. For example, it gets cold or over here Cooling process hot stamped over a roll in a thermoplastic. Typical embossings are described for example in EP 1 919 071.

The electrode layers applied according to method step IV) can be applied, for example, via a printing process such as ink-jet, flexographic printing, screen printing, spraying or via a doctor blade, a nozzle or roller and via a metallization in a vacuum. Typical materials are carbon based or based on metals such as silver, copper, aluminum, gold, nickel, zinc or other conductive metals as well as materials. The metal can be applied as a salt or as a solution, as a dispersion or emulsion and also as a precursor. The adhesion is adjusted so that the layers in each case still adhere to each other.

The following is an example of a large-scale process for the continuous production of the multilayer polyurethane film according to the invention. Show:

1 shows a schematic structure of a multi-layer coating device,

2 shows an actuator with structured electrode and contacting of the layers and

Fig. 3 is a process diagram illustrating the Herstellungsprozes ses of a multilayer polyurethane coating system.

Figure 1 shows the schematic structure of the coating system used. In the figure, the individual components have the following reference numerals:

 1 storage tank

 2 metering device

 3 vacuum degassing device

 4 filters

 5 Static mixer

 6 Coating device (doctor blade, injection printer, spray unit, or the like)

 7 circulating air dryer

 8 conveyor belt

9 Optional cover layer Component b) is introduced into one of the two storage containers 1 of the coating installation. In the second reservoir 1, the component a) is filled. Both components are then conveyed through the metering devices 2 to the vacuum degassing device 3 and degassed. From here they are then each passed through the filter 4 in the static mixer 5, in which the mixing of the components takes place. The resulting liquid mass is then fed to the coating device 6.

 The coating device 6 in the present case is a slot nozzle or a squeegee. The mixture is applied to a support with the aid of the coating device 6, the aforesaid mixture being applied on a conveyor belt 8 as a wet film (station 1 in FIG. 3) and then cured in the circulating-air dryer 7 (station 2 in FIG. 3). In this case, a dielectric polyurethane is obtained on a support, which is then optionally provided with a cover layer 9 (dust reduction), which is then removed again in a subsequent step. However, the use of a cover layer 9 is not preferred. If the conveyor belt 8 is a linear conveyor belt, the sample is subsequently removed therefrom and fed to a further coating station (station 3 in FIG. 3), where in a second step the electrode layer is applied and subsequently dried (station 4 or 2 in Fig. 3). Then, the polyurethene coated in this way is returned to the processing unit (station I in FIG. 3) shown in FIG. 1 for the purpose of applying another polyurethane layer, etc. Typical embodiments include a repetitive production system (dashed lines) Arrows in Fig. 3), such as a circulating conveyor belt or a carousel. This is a quasi-continuous process (solid parts in FIG. 3), wherein the intermediate layers are not isolated.

 A further subject of the present invention is a multilayer dielectric polyurethane film system produced by the process according to the invention. In addition, an obtainable by this method electromechanical transducer is the subject of the invention.

In the case of the electromechanical transducer, the electrode layer is applied to the layers in such a way that it can be contacted from the sides and does not stand above the dielectric film edge, since otherwise breakdowns occur. It is usual to allow a safety margin between the electrode and the dielectric so that the electrode area is smaller than the dielectric area. The electrode is structured such that a conductor track is led out for electrical contacting. A typical picture is shown in FIG. 2. The converter can be advantageously used in a variety of configurations for the production of sensors, actuators and / or generators.

Another object of the present invention is therefore an electronic and / or electrical device, in particular a module, automaton, instrument or a component comprising an electromechanical transducer according to the invention.

Furthermore, the present invention relates to the use of an electromechanical transducer according to the invention in an electronic and / or electrical device, in particular in an actuator, sensor or generator. Advantageously, the invention in a variety of different applications in elektr omechanis chen and elektr oakustis chen area, especially in the field of energy from mechanical vibrations (energy harvesting), acoustics, ultrasound, medical diagnostics, acoustic microscopy, the mechanical Sensor technology, in particular pressure force and / or strain sensors, the robotics and / or communication technology can be realized. Typical examples include pressure sensors, electro-acoustic transducers, microphones, loudspeakers, vibration transducers, light deflectors, diaphragms, optical fiber modulators, pyroelectric detectors, capacitors and control systems, and "intelligent" floors, as well as mechanical energy conversion systems, in particular rotating or oscillating movements. into electrical energy.

The invention will be explained in more detail below with reference to examples.

Unless otherwise indicated, all percentages are by weight. Unless otherwise noted, all analytical measurements would be carried out at temperatures of 23 ° C under normal conditions.

methods: NCO contents were determined volumetrically in accordance with DIN EN ISO 1 1909, unless expressly stated otherwise.

The indicated viscosities were determined by rotational viscometry according to DIN 53019 at 23 ° C with a rotary viscometer Anton Paar Germany GmbH, Germany, I felmulli-l lirth- Str 6, 73760 Ostfildern.

Measurements of film thicknesses were made with a mechanical probe from Dr. Ing. Johannes Heidenhain GmbH, Germany, Dr.-Johannes-I Leidenhain-Slr. 5, 83301 Traunreut. The specimens were measured at three different locations and the mean value was used as a representative measurement. The tensile tests were carried out by means of a tractor from Zwick, model number 1455, equipped with a load cell of the official calibration lkN according to DIN 53 504 with a load cell

Train speed of 50 mm / min performed. 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. Specifically, in addition to the tensile strength in [MPa] and the elongation at break in [%], the stress in [MPa] at 100% and 200% elongation was determined.

The determination of the permanent elongation was carried out by means of a tractor Zwicki Zwick / Roell equipped with a load cell of the total measuring range of 50 N, on a S2 rod of the sample to be examined. In this measurement, the sample is stretched with a volumetric efficiency of 50 mm / min up to n * 50%; after this deformation has been reached, the sample is relieved to force = 0 N and the remaining strain is then determined. Immediately afterwards, the next measuring cycle starts with n = n + 1; the value of n is increased until the sample breaks. I only measure the value for 50% deformation.

The determination of the stress relaxation was also carried out on the tractor Zwick; the instrumentation corresponds to the attempt to determine the permanent strain. The sample used was a strip-shaped sample of the dimension 60 × 10 mm ² , which was clamped with a clamp spacing of 50 mm. After a very rapid deformation to 55 mm, this deformation was held constant for a period of 30 minutes and during this time the catheter was closed. The stress relaxation after 30 minutes is the percentage decrease in stress, relative to the initial value immediately after deformation to 55 mm.

The measurements of the dielectric constant in accordance with ASTM D 1 50-98 were carried out using a measuring setup from Novocontrol Technologies GmbH & Co. KG, Obererbacher Strasse 9, 56414 Hundsangen, Germany. Germany (measuring bridge: Alpha-A Analyzer, measuring head: ZGS Active Sample Cell Test Interface) with a diameter of the test piece of 20 mm. Analyzes it was a frequency range of 10 ⁷ Hz to 10 ^"2 Hz. As a measure of the dielectric constant of the investigated material, the real part of the dielectric constant has been selected at 10 to 0.01 Hz. The determination of the electrical recovery prior done by means of a Laborau tbaus Fa. Keithley Instruments (Keithley Instruments GmbH, Landsberger Strasse 65, D-82 1 10 Germering Germany) Model No .: 6517 A and 8009 according to ASTM D 257, a method for determining the insulation resistance of materials.

Fracture field strength was determined according to ASTM D 149-97a using a model HypotMAX high voltage source from Associated Research Inc, 13860 W Laurel

Drive. L ke Forest, IL 600045-4546, USA and a self-constructed sample holder.

The sample holder contacts the homogeneously thick polymer samples with only a small amount of mechanical force

Preload and prevents the operator from coming into contact with the tension. The non-prestressed polymer film is statically loaded in this structure with increasing voltage until an electrical breakdown takes place through the film. Measurement result is that achieved at break-through

Stress, based on the thickness of the polymer film in [ν / μηι]. There are 5 measurements per slide and the mean value is given.

To investigate whether a boundary layer is present, a confocal microscope (confocal laser scanning microscopy, LSCM) was used. These devices use laser light to excite fluorescent dyes, so they are fluorescent microscopes.

Substances used and abbreviations: Desmodur ^® N100 biuret based on hexamethylene diisocyanate, NCO content 220 ± 0.3%

 (according to DIN EN ISO 1 909), viscosity at 23 ° C 10000 ± 2000 mPas, Bayer Materials Science AG, Leverkusen, DE

Desmodur * N75 MPA 75% Desmodur® N100 and 25% methoxypropyl acetate, 250 ± 75 mPas,

Bayer Materials Science AG, Leverkusen, DE P200H / DS polyester polyol based on 1,6-hexanediol and phthalic anhydride,

Molar weight 2000 g / mol, Bayer MaterialScience AG, Leverkusen, DE

Desmophen® C2201 polycarbonate polyol, based on 1.6-1 lex andiol. manufactured by

 Reaction with dimethyl carbonate, molecular weight 2000 g / mol, Bayer MaterialScience AG, Leverkusen, DE

Ketjenblack EC 300 J Product of Akzo Nobel AG

Cabot CCI-300 (silver dispersion from Cabot)

Tib Kat 220 Butyltin tris (2-ethylhexanoate), from Tib Chemicals AG, Mannheim

BYK 310 Solution of a polyester-modified polydimethylsiloxane, Altana BYK 3441 Solution of an acrylate copolymer, Altana.

Methoxypropyl acetate from Sigma-Aldrich.

Hostaphan R N 2SLK: release film from Mitsubishi based on polyethylene terephthalate with

 Silicone coating. A 300 mm wide film was used.

Baytubes® C150P: Multilayered carbon nanotubes from Bayer MaterialScience AG Release paper: Polymethylpentene-coated release paper.

For the coating experiments of the examples according to the invention, a squeegee system from Zehntner was used for the dielectric film. The substrate was dried as follows:

A first drying section was at 80 ° C (2 m / s supply air), a second drying section at 100 ° C (3 m / s supply air), a third drying section at 1 10 ° C (8 m / s supply air), a fourth drying section operated at 130 ° C (7, 5, 2, 2 m's supply air). The web speed of the carrier was controlled at 1 m / min; as incoming air, dry air was blown into the drying sections. The layer thickness of the finished dielectric polyurethane film was 100 μηι.

As a next step, the electrodes were applied. For this purpose either a spraying device from Hansa (airbrush), a screen printing machine from Thieme Model 3030, an inkjet printer from Fujifilm Di mal ix or a doctor blade from Zehntner (ZAA 2300) were used. There were 21.39 parts by weight Desmodur N100, reacted with a polyol mixture of 0.0024 parts by weight of Tib Kat 220 and 100 parts by weight of P200H / DS with each other. The isocyanate (Desmodur N100) was used at 40 ° C, the polyol mixture (P200H / DS with TIB Kat 220) at 80 ° C. The respective components were heated to 40 ° C and 80 ° C, respectively. The static mixer was heated to 6 5 ° C, the doctor blade had 60 ° C. The ratio of NGO to OH groups was 1, 07. It was poured onto the Hostaphan film.

Example 2:

There were 21.39 parts by weight of Desmodur N100, reacted with a polyol mixture of 0.0024 parts by weight of Tib Kat 220 and 100 parts by weight of Desmophen C2201 with each other. The isocyanate (Desmodur N100) was used at 40 ° C, the polyol blend (Desmophen C2201 with TIB Kat 220) at 80 ° C. The hoses of the respective components were heated to 40 ° C respectively 80 ° C. The static mixer was heated to 65 ° C, the squeegee had 60 ° C. The ratio of NGO to OH groups was 1, 07. It was poured onto the Hostaphan film.

There were 151.50 parts by weight of Desmodur N75 MPA, with a polyol blend of 0.02 parts by weight of Tib Kat 220 and 536.84 parts by weight of P200H / DS, 3.24 parts by weight of Byk 310 and 308 , 41 parts by weight of methoxypropyl acetate reacted with each other. The isocyanate (Desmodur N75 MPA) was used at 23 ° C, the polyol mixture (P200H / DS with TIB Kat 220) at 23 ° C. The hoses, the static mixer and the squeegee were each at 23 ° C. The ratio of NGO to Ol I groups was 1, 07. It was poured onto the paper.

example

There were 1 13.62 parts by weight of Desmodur N75 BA, with a polyol mixture of 0.01 parts by weight of Tib Kat 220 and 459.30 parts by weight of P200H / DS, 2.77 parts by weight of Byk 3441 and 158.31 parts by weight of butyl acetate reacted with each other. The isocyanate (Desmodur N75 BA) was used at 23 ° C, the polyol mixture (P200H / DS with TIB Kat 220) at 23 ° C. The hoses, the static mixer and the squeegee were each at 23 ° C. The ratio of NGO to OH groups was 1, 07. It was poured onto the paper.

Example 5:

There were 1 13.62 parts by weight of Desmodur N75 BA, with a polyol mixture of 0.01 parts by weight of Tib Kat 220 and 459.30 parts by weight of P200H / DS, 2.77 parts by weight of Byk 3441 and 158.31 parts by weight of butyl acetate and 2 parts by weight Ketjenbiack EC 300 J reacted with each other. The Isocyanate (Desmodur N75 BA) was used at 23 ° C, the polyol mixture (P200H / DS with TIB Kar 220) at 23 ° C. The hoses, the static mixer and the squeegee were each at 23 ° C. The layer thickness was 20 μηχ after drying

Example 6-9: 1 was alternately 5 so that 500 layers could be made. Accordingly, 2-4 in combination with 5 were used.

Example 10:

It was prepared in 4 layers and sprayed with Ketjenbiack EC 300J. There were sprayed 100 μχη. The process was repeated 500 times. The resistance of the electrode layer was determined to be 1.89E + 04Ohm.

Example 1 1:

It was 4 single-layered and sprayed with Baytubes C 150P. There were sprayed 100 μιη. The process was repeated 500 times. The resistance of the electrode layer was determined to 1.54 ι 04 () hm. Example 12:

It was made in 4 layers and printed by Inkjet with Cabot CCI-300. It was dried. There were 5 μηι electrode applied. The process was repeated 500 times. The resistance of the electrode layer was determined to be 1.75 + 3 ohms.

Comparative Example 1

Two polyurethane films prepared according to Example 4 were used. Two foils of polyurethane were stacked on top of each other and laminated with a laminator with two rubber rollers under 3 bar pressure and a blowing speed of 5 mm / second.

The layers could be pulled apart again after lamination. Comparative Example 2:

 Two polyurethane films prepared according to Example 4 were used. Two polyurethane films were stacked on top of each other and laminated with a laminator with two rubber rollers under 3 bar pressure and 100 ° C temperature (roll tempera- ture) and a blowing speed of 5 mm / second.

The layers could be pulled apart again after lamination. Comparative Example 3

 Two polyurethane films prepared according to Example 1 were used. For this purpose, two films of polyurethane were placed on each other and laminated with a laminator with two rubber rollers under 3 bar pressure and 100 ° C temperature (roller temperature) and a speed of 5 mm / second.

 The layers could be pulled apart again after lamination. Comparative Example 4

Two polyurethane films prepared according to Example 2 were used. For this purpose, two polyurethane films were stacked on top of each other and with a laminator with two rubber rollers under 3 bar pressure and 100 ° C temperature (Rollentemp er atur) and a speed of 5 mm /

Second laminated.

 The layers could be pulled apart again after lamination.

Comparative Example 5:

 Two polyurethane films prepared according to Example 3 were used. For this purpose, two films of polyurethane were placed on each other and laminated with a laminator with two rubber rollers under 3 bar pressure and 100 ° C temperature (roller temperature) and a speed of 5 mm / second.

 The layers could be pulled apart again after lamination.

Comparative Example 6:

 Two polyurethane films prepared according to Example 4 were used. For this purpose, two films of polyurethane were placed on each other and laminated with a laminator with two rubber rollers under 3 bar pressure and 100 ° C temperature (roller temperature) and a speed of 5 mm / second.

 The layers could be pulled apart again after lamination. It turns out that a solid layer composite is only possible by the process according to the invention by the layers are gradually chemically crosslinked to each other.

Evaluation of Examples and Comparative Examples: The electrical resistance and breakdown field strength were determined on the films. The results for the comparative examples and the examples according to the invention are shown in Table 1 below.

Table 1: Electrical / mechanical properties of a monolayer:

In Example 5, the resistance was determined to be I, 10E + 04, so that it is a conductive layer.

All films showed a very high electrical resistance and high breakdown field strength. The films according to the invention can be used in particular for the production of electromechanical converters with particularly good efficiencies. Due to the 500-layer structure, a 500-fold deflection could be achieved. The multi-layer structure had no negative effects on the properties and even after several cycles the properties were unchanged and there were no delaminations. The layers behaved for one shift.

Claims

claims

1. A process for producing a multilayer dielectric polyurethane film system

(Mulitlayer) with the following process steps:

I) Preparing a mixture comprising a) a compound containing isocyanate groups with a content of

 Isocyanate groups of> 10 wt .-% and <50 wt .-%, b) an isocyanate-reactive group-containing compound having an Ol I number of> 20 and <150, wherein the sum of the number average functionality of isocyanate groups and isocyanate-reactive Groups of compounds a) and b)> 2.6 and <6,

II) Applying the mixture immediately after its preparation in the form of a

 Wet film on a support,

III) curing the wet film to form the polyurethane film and

IV) applying an electrode layer to the almost completely dried film,

V) repeating steps I) -IV) to produce a multilayer system.

2. The method according to claim 1,

 characterized in that

 the electrode layer applied in step IV) is structured or segmented.

3. The method according to any one of claims 1 or 2,

 characterized in that

 the application of the electrode layer according to step IV) by spraying, pouring, knife coating, inkjet or the like takes place.

4. The method according to any one of claims 1 to 3,

 characterized in that

 the electrode layer contains a binder.

5. The method according to any one of claims 1 to 4,

 characterized in that

the electrode layer after application according to step IV) is dried.

6. The method according to any one of claims 1 to 5,

 characterized in that

 the steps I) to IV) according to step V)> 2 and <1000000 times, more preferably> 5 and <100000 and especially preferably> 10 and <10000, very particularly preferably> 10 and <5000 and especially very particularly preferably> 20 and <1000 are repeated.

A multilayer dielectric polyurethane film system obtainable by a process according to any one of claims 1 to 6.

8. Electromechanical transducer comprising a multilayer dielectric

 Polyurethane film system according to claim 7.