HK1159144A - Electromechanical transducer having a polyisocyanate-based polymer element - Google Patents

Description

Electromechanical transducer with polyisocyanate-based polymer element

The invention relates to an electromechanical transducer (electromechanic transducer) with a polymer element (polymer element), in particular an electromechanical sensor, actuator (Aktuator) and/or Generator (Generator), wherein the polymer element is obtainable from a reaction mixture comprising a polyisocyanate or a polyisocyanate prepolymer or a mixture thereof and a compound having at least two isocyanate-reactive amino groups. In addition, the invention relates to a method for producing such an electromechanical transducer, and to the use of such a polymer element as an actuator, sensor and/or generator. Furthermore, the invention relates to an electronic and/or electrical device comprising the electromechanical transducer according to the invention, and to the use of the electromechanical transducer according to the invention in an electronic and/or electrical device.

Electromechanical transducers convert electrical energy into mechanical energy and vice versa. Thus, the electromechanical transducer may be used as a sensor, an actuator and/or a generator.

The basic structure of such a transducer is based on an electroactive polymer layer covered on both sides with electrodes. In this connection, the expression "electroactive polymer" is understood to mean a polymer which changes its volume and/or shape depending on the voltage applied to it and/or a polymer which is capable of generating a voltage due to a change in volume and/or shape.

WO 01/06575 a1 discloses that these properties can be exhibited by, for example, silicone elastomers, acrylic elastomers, polyurethanes, thermoplastic elastomers, polytetrafluoroethylene-containing copolymers, fluoroelastomers, and polymers containing silicone groups and acrylic groups.

Furthermore, it is known from EP 1081171A 2 and DE-A10246708A 1 that polyurethane prepolymers can be crosslinked by means of aspartic acid esters.

However, conventional polymers for electromechanical transducers often exhibit poor mechanical and other properties, in particular poor elongation properties, low insulating effect, in particular low breakdown field strength and high electrical conductivity, poor processability and high raw material costs. In particular, with polymers conventionally used for electromechanical transducers, such as silicone, a combination of desired properties cannot be obtained by one material.

The object of the present invention is thus to obtain an electromechanical transducer which overcomes the drawbacks of the known electromechanical transducers.

Within the scope of the present invention, it has been found that this object is achieved by a polymeric element obtainable from a reaction mixture comprising a polyisocyanate or a polyisocyanate prepolymer or a mixture thereof and a compound having at least two isocyanate-reactive amino groups, wherein the compound having at least two isocyanate-reactive amino groups is in particular an amino-functional aspartate. In this connection, within the scope of the present invention, the terms "polyisocyanate" and "polyisocyanate prepolymer" are understood to mean compounds having at least two free isocyanate groups. In other words, the terms "polyisocyanate" and "polyisocyanate prepolymer" are understood to mean a compound having at least two isocyanate functional groups.

The invention thus provides an electromechanical transducer having at least two electrodes and at least one polymer element, wherein the polymer element is mounted between the two electrodes and is in particular in contact with at least one of the electrodes, and the polymer element is obtainable according to the invention from a film-forming reaction mixture, for example comprising

A) A polyisocyanate or polyisocyanate prepolymer or a mixture thereof, and

B) a compound having at least two isocyanate-reactive amino groups.

In the context of the present invention, the terms "ein" and "ein" in respect of components A) and B) are not used as numerals but as indefinite articles.

If a mechanical load is applied to such a transducer, the transducer deforms, for example, in the direction of its thickness, and a strong electrical signal is detectable at the electrodes. Thereby, the mechanical energy is converted into electrical energy. Thus, the transducer according to the invention can be used both as a generator and as a sensor.

On the other hand, by using the opposite effect, i.e. the conversion of electrical energy into mechanical energy, the transducer of the invention can equally be used as an actuator.

Within the scope of one embodiment of the invention, the polymer element is arranged between two electrodes in such a way that the electrodes adjoin the polymer element on opposite sides of the polymer element. For example, the polymer element may be covered with electrodes on both sides.

The invention further provides a method of producing an electromechanical transducer according to the invention, wherein

-providing at least two electrodes, and

-providing a polymeric element by reacting a reaction mixture comprising

A) A polyisocyanate or polyisocyanate prepolymer or a mixture thereof, and

B) a compound having at least two isocyanate-reactive amino groups,

and

-arranging the polymer element between two electrodes.

In particular, in this regard, the polymer element may be disposed between two electrodes in such a way that the polymer element is in contact with at least one of the electrodes.

Within the scope of a preferred embodiment of the method according to the invention, the polymer element is provided by applying a reaction mixture to at least one of the electrodes. This can be achieved, for example, by knife coating, brushing, casting (Gie β en), centrifuging, spraying or extrusion. However, it is also within the scope of the invention to produce the electrode and the polymer element in separate steps and subsequently assemble them together.

Within the scope of a preferred embodiment of the process according to the invention, the reaction mixture is dried and/or annealed (tempern). In this connection, the drying can be carried out, for example, in a temperature range of ≥ 0 ℃ to ≤ 200 ℃ for a period of ≥ 0.1min to ≤ 48h, in particular ≥ 6h to ≤ 18 h. The annealing can be carried out, for example, at a temperature ranging from 80 ℃ to 250 ℃ for a period of time ranging from 0.1min to 24 h.

The invention further provides the use of a polymer element obtainable from a reaction mixture comprising the following components as an electromechanical element, such as a sensor, an actuator and/or a generator, in particular as an electromechanical element in a sensor, an actuator and/or a generator:

A) a polyisocyanate or polyisocyanate prepolymer or a mixture thereof, and

B) a compound having at least two isocyanate-reactive amino groups.

The invention further provides an electronic and/or electrical device, in particular a module (Baustein), a robot, an appliance or an assembly, comprising the electromechanical transducer of the invention.

Furthermore, the invention relates to the use of an electromechanical transducer according to the invention in an electronic and/or electrical device, in particular in a module, a robot, an appliance or an assembly.

Within the scope of the invention, the polymer element may be a polymer layer, in particular a polymer film (Polymerfilm), a polymer foil (Polymerfoie) or a polymer coating. For example, the polymer layer can exhibit a layer thickness of ≥ 0.1 μm to ≤ 1500 μm, for example ≥ 1 μm to ≤ 500 μm, in particular ≥ 5 μm to ≤ 200 μm, preferably ≥ 5 μm to ≤ 100 μm.

Component A)

Within the scope of the present invention, component A) may in principle be polyisocyanates or polyisocyanate prepolymers or mixtures thereof. For example, component a) may be a polyisocyanate containing isocyanurate and/or urethane groups, or a polyisocyanate prepolymer containing isocyanurate and/or urethane groups or a mixture thereof.

Suitable polyisocyanates A) are, for example, 1, 4-butylidene diisocyanate, 1, 6-Hexylidene Diisocyanate (HDI), isophorone diisocyanate (IPDI), 2, 4-and/or 2,4, 4-trimethylhexamethylene diisocyanate, the isomer bis (4,4 '-isocyanatocyclohexyl) methane or mixtures thereof having any isomer content, 1, 4-cyclohexylidene diisocyanate, 4-isocyanatomethyl-1, 8-octane diisocyanate (nonane triisocyanate), 1, 4-phenylene diisocyanate, 2, 4-and/or 2, 6-tolylene diisocyanate, 1, 5-naphthylene diisocyanate, 2' -and/or 2,4 'and/or 4, 4' -diphenylmethane diisocyanate, 1, 3-and/or 1, 4-bis (2-isocyanatoprop-2-yl) benzene (TMXDI), 1, 3-bis (isocyanatomethyl) benzene (XDI), alkyl 2, 6-diisocyanatohexanoate having an alkyl group of 1 to 8 carbon atoms (lysine diisocyanate), and mixtures thereof.

In addition to the polyisocyanates mentioned above, it is also possible to use, in part (anteilig), those exhibiting a functionality of 2 or more with uretdione, isocyanurate, urethane, allophanate, biuret, iminoimineDiazinedione orModified diisocyanates with diazinetrione structure and their mixture.

Preference is given to polyisocyanates or polyisocyanate mixtures of the abovementioned type having exclusively aliphatically or cycloaliphatically bonded isocyanate groups or mixtures thereof, and the average NCO functionality of the mixtures is from 2 to 4, preferably from 2 to 2.6, particularly preferably from 2 to 2.4.

Particularly preferably, polyisocyanates based on hexamethylene diisocyanate, isophorone diisocyanate or the isomer bis (4, 4' -isocyanatocyclohexyl) methane and mixtures of the abovementioned diisocyanates are used as component A).

Polyisocyanate prepolymers which are likewise usable as component A) can be obtained by converting polyisocyanates with hydroxy-functional, in particular polymeric, polyols, optionally with the addition of catalysts and auxiliaries and additional substances.

The hydroxyl-functional polymer polyols may be, for example, polyester polyols, polyacrylate polyols, polyurethane polyols, polycarbonate polyols, polyether polyols, polyester-polyacrylate polyols, polyurethane-polyester polyols, polyurethane-polyether polyols, polyurethane-polycarbonate polyols and/or polyester-polycarbonate polyols. These may be used alone or in any mixture with each other for the purpose of producing the polyisocyanate prepolymer.

For the purpose of producing polyisocyanate prepolymers, polyisocyanates, preferably diisocyanates, can be reacted with polyols in NCO/OH ratios of usually ≥ 4:1 to ≤ 20:1, for example 8: 1. The unconverted polyisocyanate component can then be separated off. For this purpose, thin-layer distillation methods can be used, so that low residual monomer products having residual monomer contents of, for example,. ltoreq.1% by weight, preferably,. ltoreq.0.5% by weight, particularly preferably,. ltoreq.0.1% by weight, are obtained. In this connection, the reaction temperature is generally from ≥ 20 ℃ to ≤ 120 ℃ and preferably from ≥ 60 ℃ to ≤ 100 ℃. During production, stabilizers such as benzyl chloride, isophthaloyl chloride, dibutyl phosphate, 3-chloropropionic acid or methyl tosylate may optionally be added.

Polyester polyols suitable for the production of polyisocyanate prepolymers may be polycondensates of diols and optionally triols and tetraols, with dicarboxylic acids and optionally tricarboxylic acids and tetracarboxylic acids or hydroxycarboxylic acids or lactones. Instead of the free polycarboxylic acids, it is also possible to use the corresponding polycarboxylic anhydrides or the corresponding polycarboxylic lower alcohol esters for the production of the polyesters.

Examples of suitable diols in this connection are ethylene glycol, butanediol, diethylene glycol, triethylene glycol, polyalkylene glycols such as polyethylene glycol, also 1, 2-propanediol, 1, 3-propanediol, butanediol (1,3), butanediol (1,4), hexanediol (1,6) and isomers thereof, neopentyl glycol or neopentyl glycol hydroxypivalate or mixtures thereof, preference being given to hexanediol (1,6) and isomers thereof, butanediol (1,4), neopentyl glycol and neopentyl glycol hydroxypivalate. In addition to these, polyols such as trimethylolpropane, glycerol, erythritol, pentaerythritol, trimethylolbenzene or trishydroxyethyl isocyanurate or mixtures thereof may be used.

As the dicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, cyclohexanedicarboxylic acid, adipic acid, azelaic acid, sebacic acid, glutaric acid, tetrachlorophthalic acid, maleic acid, fumaric acid, itaconic acid, malonic acid, suberic acid, 2-methylsuccinic acid, 3-diethylglutaric acid and/or 2, 2-dimethylsuccinic acid can be used. The corresponding anhydrides may also be used as acid sources.

If the average functionality of the polyol to be esterified is > 2, monocarboxylic acids such as benzoic acid and heptanoic acid (Hexancabons ä ure) can additionally be used synergistically.

Preferred acids are aliphatic or aromatic acids of the type described above. Adipic acid, isophthalic acid and phthalic acid are particularly preferred in this connection.

In the production of polyester polyols having terminal hydroxyl groups, hydroxycarboxylic acids which can be used synergistically as reaction partners are, for example, hydroxycaproic, hydroxybutyric, hydroxydecanoic or hydroxystearic acid or mixtures thereof. Suitable lactones are caprolactone, butyrolactone or homologues or mixtures thereof. Caprolactone is preferred in this connection.

Likewise, based on the production of polyisocyanatesFor the purposes of the substance A), polycarbonates having hydroxyl groups, such as polycarbonate polyols, preferably polycarbonate diols, can be used. For example, the number average molecular weight M can be used_nFrom not less than 400g/mol to not more than 8000g/mol, preferably from not less than 600g/mol to not more than 3000 g/mol. These are obtainable by reacting carbonic acid derivatives such as diphenyl carbonate, dimethyl carbonate or phosgene with polyhydric alcohols, preferably diols.

Examples of diols suitable for this purpose 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, 4-trimethylpentanediol-1, 3, dipropylene glycol, polypropylene glycol, dibutylene glycol, polybutylene glycol, bisphenol A or lactone-modified diols of the abovementioned type or mixtures thereof.

In this connection, the diol component preferably comprises ≥ 40% by weight and ≤ 100% by weight of hexanediol, preferably 1, 6-hexanediol and/or hexanediol derivatives. Such hexanediol derivatives are based on hexanediol and may have, in addition to terminal OH groups, ester or ether groups. Such derivatives can be obtained, for example, by reacting hexanediol with an excess of caprolactone, or by etherification of hexanediol with itself to give dihexylene glycol or trihexylene glycol. Within the scope of the present invention, the amounts of these and other components are chosen in a known manner in such a way that the total amount does not exceed 100% by weight, and in particular is equal to 100% by weight.

Polycarbonates having hydroxyl groups, in particular polycarbonate polyols, are preferably of linear structure.

For the purpose of producing the polyisocyanate prepolymers A), polyether polyols can likewise be used. Suitable are, for example, polytetramethylene glycol polyethers, such as those which can be obtained by cationic ring-opening polymerization of tetrahydrofuran. Suitable polyether polyols may also be addition products of styrene oxide, ethylene oxide, propylene oxide, butylene oxide and/or epichlorohydrin on difunctional or polyfunctional starter molecules. As suitable starter molecules, for example, water, butyldiglycol, glycerol, diethylene glycol, trimethylolpropane, propylene glycol, sorbitol, ethylenediamine, triethanolamine or 1, 4-butanediol or mixtures thereof can be used.

Preferred components for producing the polyisocyanate prepolymers are polypropylene glycol, polytetramethylene glycol polyether and polycarbonate polyols or mixtures thereof, polypropylene glycol being particularly preferred.

In this connection, the number average molecular weight M may be employed_nFrom not less than 400g/mol to not more than 8000g/mol, preferably from not less than 400g/mol to not more than 6000g/mol and particularly preferably from not less than 600g/mol to not more than 3000 g/mol. These substances preferably exhibit an OH functionality of ≥ 1.5 to ≤ 6, particularly preferably ≥ 1.8 to ≤ 3, very particularly preferably ≥ 1.9 to ≤ 2.1.

In addition to the polymer polyols described, short-chain polyols can also be used in the production of the polyisocyanate prepolymers A). For example, ethylene glycol, diethylene glycol, triethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, 1, 3-butanediol, cyclohexanediol, 1, 4-cyclohexanedimethanol, 1, 6-hexanediol, neopentyl glycol, hydroquinone dihydroxyethyl ether, bisphenol A (2, 2-bis (4-hydroxyphenyl) propane), hydrogenated bisphenol A (2, 2-bis (4-hydroxycyclohexyl) propane), trimethylolpropane, trimethylolethane, glycerol or pentaerythritol or mixtures thereof may be used.

Also suitable in this molecular weight range are ester diols, such as α -hydroxybutyl-e-hydroxyhexanoate, ω -hydroxyhexyl- γ -hydroxybutyrate, β -hydroxyethyl adipate or bis (β -hydroxyethyl) terephthalate.

Furthermore, monofunctional isocyanate-reactive compounds containing hydroxyl groups may also be used for the purpose of producing polyisocyanate prepolymers. 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.

In addition, canReacting NH₂The functional and/or NH-functional components are used for the purpose of producing the polyisocyanate prepolymers A).

Suitable components for the purpose of chain extension are organic diamines or polyamines. For example ethylenediamine, 1, 2-diaminopropane, 1, 3-diaminopropane, 1, 4-diaminobutane, 1, 6-diaminohexane, isophoronediamine, isomer mixtures of 2,2, 4-and 2,4, 4-trimethylhexamethylenediamine, 2-methylpentanediamine, diethylenetriamine, diaminodicyclohexylmethane or dimethylethylenediamine or mixtures thereof.

In addition, compounds having secondary amino groups in addition to primary amino groups, or OH groups in addition to amino groups (primary or secondary), can also be used for the purpose of producing the polyisocyanate prepolymers A). 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 the purpose of chain termination, the usual amines containing groups reactive toward isocyanates are used, 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, amidoamines (Amidamines) formed from diprimary amines and monocarboxylic acids, monoketames of diprimary amines, primary/tertiary amines, such as N, N-dimethylaminopropylamine.

The isocyanates, polyisocyanates, polyisocyanate prepolymers or isocyanate mixtures used in A) preferably have an average NCO functionality of from ≥ 1.8 to ≤ 5, particularly preferably from ≥ 2 to ≤ 3.5 and very particularly preferably from ≥ 2 to ≤ 2.5.

Component B)

Within the scope of the present invention, component B) can in principle be a compound having at least two isocyanate-reactive amino groups. For example, component B) may be a polyamine having at least two isocyanate-reactive amino groups. In this connection, within the scope of the present invention, the expression "isocyanate-reactive amino group" is understood to mean NH₂A radical or an NH radical.

Component B) is preferably or comprises amino-functional aspartic acid esters, in particular amino-functional polyaspartic acid esters.

The amino-functional aspartic acid esters B) which are preferably used can be produced by reacting the corresponding at least difunctional primary amines X (NH)₂)_nWith maleic or fumaric esters of the general formula.

Preferred maleic or fumaric acid esters are dimethyl maleate, diethyl maleate, dibutyl maleate and the corresponding fumaric acid esters. Preferred at least difunctional primary amines X (NH)₂)_nIs ethylenediamine, 1, 2-diaminopropane, 1, 4-diaminobutane, 1, 6-diaminohexane, 2, 5-diamino-2, 5-dimethylhexane, 2-methyl-1, 5-diaminopentane, 2, 4-and/or 2,4, 4-trimethyl-1, 6-diaminohexane, 1, 11-diaminoundecane, 1, 12-diaminododecane, 1-amino-3, 3, 5-trimethyl-5-aminomethylcyclohexane, 2, 4-and/or 2, 6-hexahydromethylenephenylenediamine, 2,4 ' -and/or 4,4 ' -diaminodicyclohexylmethane, 3 ' -dimethyl-4, 4 ' -diaminodicyclohexylmethane, 2,6 ' -diaminodicyclohexylmethane, 2,5 ' -diaminocyclohexane, 2,4 ' -dimethylcyclohexane, 2,4 ' -diaminohexane, 2, 6-dimethylhexane, 2, 5-dimethylhexane, 2,4 ' -diaminoundecane, 2,5, 2,4, 4' -triamino-5-methyldicyclohexylmethane and number-average molecular weight M_nFrom 148 to 6000g/mol of polyetheramines having aliphatically bound primary amino groups or mixtures thereof. Particularly preferred at least difunctional primary amines are 4-diaminobutane, 1, 6-diaminohexane, 2-methyl-1, 5-diaminopentane, 2, 4-trimethyl-1, 6-diaminohexane or 2,4, 4-trimethyl-1, 6-diaminohexane or mixtures thereof.

Within the scope of a preferred embodiment of the present invention, component B) is or comprises an amino-functional aspartic acid ester of the general formula (I):

wherein

X represents an n-valent organic residue obtained by removing at least two primary amino groups of an n-membered amine,

r1, R2 represent identical or different organic residues which do not contain Zerewitinoff-active Waterstoff, and

n represents an integer of 2 or more.

In the formula (I), X preferably represents a divalent organic residue obtained by removing an amino group of 1, 4-diaminobutane, 1, 6-diaminohexane, 2-methyl-1, 5-diaminopentane, 2, 4-or 2,4, 4-trimethyl-1, 6-diaminohexane.

In this connection, the expression "zerewitinoff-active hydrogen" is understood within the scope of the present invention to mean the bound hydrogen of methane which is provided by reaction with methyl magnesium iodide according to the process found by zerewitinoff. In particular, OH groups, NH groups and SH groups are understood within the scope of the present invention to be groups having Zerewitinoff-active hydrogens. Examples of the compound having zerewitinoff-active hydrogen are compounds containing a carboxyl group, a hydroxyl group, an amino group, an imino group or a thiol group as a functional group.

Thus, R₁And R₂Preferably identical or different organic residues having no OH, NH or SH groups.

Within the scope of one embodiment of the present invention, R₁And R₂In each case independently of one another, linear or branched alkyl radicals having from 1 to 10 carbon atoms, particularly preferably methyl or ethyl.

Within the scope of a preferred embodiment of the present invention, R₁And R₂Represents ethyl, wherein X is based on 2-methyl-1, 5-diaminopentane as n-member.

In formula (I), n preferably represents the number of n-membered amines (Wertigkeit), which is an integer from ≥ 2 to ≤ 6, particularly preferably from ≥ 2 to ≤ 4, for example 2.

The production of the amino-functional aspartic acid esters B) from the starting materials can be carried out according to DE 69311633A. The production of the amino-functional aspartic acid esters B) is preferably carried out at a temperature in the range from ≥ 0 ℃ to ≤ 100 ℃. In this connection, the starting materials are preferably used in such a ratio that at least one, preferably exactly one, olefinic double bond is assigned to each primary amino group. After the reaction, the starting materials optionally used in excess can be separated off by distillation. The reaction may be carried out in bulk or in a suitable solvent such as methanol, ethanol, propanol or bisIn the presence of an alkane or a mixture of such solvents. The catalysts can also be used for the purpose of producing B).

Instead of, or in addition to, amino-functional aspartates, other compounds having at least two isocyanate-reactive amino groups may be used. Examples are aliphatic, cycloaliphatic and/or aromatic diamines or polyamines, such as 1, 2-ethylenediamine, 1, 2-diaminopropane, 1, 3-diaminopropane, 1, 4-diaminobutane, 1, 6-diaminohexane, isophoronediamine, isomer mixtures of 2,2, 4-and 2,4, 4-trimethylhexamethylenediamine, 2-methylpentanediamine, diethylenetriamine, triaminononane, 1, 3-and 1, 4-tolylenediamine, alpha '-tetramethyl-1, 3-xylylenediamine, alpha' -tetramethyl-1, 4-xylylenediamine, 4, 4-diaminodicyclohexylmethane, dimethylethylenediamine, 1-methyl-3, 5-diethyl-2, 4-diaminobenzene, 1-methyl-3, 5-diethyl-2, 6-diaminobenzene, 1,3, 5-triethyl-2, 6-diaminobenzene, 3,5,3 ', 5' -tetraethyl-4, 4-diaminodiphenylmethane, 3,5,3 ', 5' -tetraisopropyl-4, 4 '-diaminodiphenylmethane, 3, 5-diethyl-3', 5 '-diisopropyl-4, 4' -diaminodiphenylmethane, polyoxyalkylene amines (polyetheramines) such as polypropylene diamine, or any mixture of such diamines, or any mixture with an amino-functional aspartate. In this connection, preference is given to using compounds having reduced reactivity toward isocyanates, for example aromatic diprimary amines which preferably have at least one alkyl group in addition to the amino group. Examples are 3, 5-diethyltoluene-2, 6-diamine (3 ‚ 5-diethyltoluol-2, 6-diamine) or 3, 5-diethyltoluene-2, 4-diamine (3, 5-diethyltoluol-2, 4-diamine) or mixtures thereof.

The reaction mixture for the polymer element according to the invention can be obtained by mixing components A) and B). In this connection, the ratio of amino groups to free NCO groups is preferably ≥ 1:1.5 to ≤ 0.8:1, particularly preferably 1:1.

The rate at which substantial crosslinking and curing of the mixtures of A) and B) is achieved at 23 ℃ may typically be from ≥ 1s to ≤ 10min, preferably from ≥ 1min to ≤ 8min, particularly preferably from ≥ 1min to ≤ 5 min. Curing may be promoted by a catalyst. Except for component B) (e.g. amino-functional aspartic acid, diamine and/or NH)₂Functional and/or NH-functional polyamines), the isocyanate groups of the polyisocyanate or polyisocyanate prepolymer component a) can also be reacted with other compounds having isocyanate-reactive groups, such as diol or polyol moieties. In a preferred embodiment, not less than 50 mole% of the isocyanate-reactive groups used for curing component A) are amino-functional aspartates. Within the scope of a particularly preferred embodiment of the present invention, component A) is cured exclusively with amino-functional aspartic esters.

In one aspect, the reaction mixture comprising components a) and B) can be applied directly to the electrode and cured thereon. Alternatively, it is also possible to first prepare a film or foil from the reaction mixture and optionally to cure it completely, and subsequently to bond it to the electrode. In this connection, binders may be used, or the viscosity of the reaction mixture itself may be utilized.

In addition to components A) and B), the reaction mixture may additionally comprise auxiliaries and additives. Examples of such auxiliaries and additives are crosslinking agents, thickeners, cosolvents, thixotropic agents, stabilizers, antioxidants, light stabilizers, emulsifiers, surfactants, binders, plasticizers, hydrophobicizing agents, pigments, fillers and flow-control agents.

In addition to components A) and B), the reaction mixture may additionally comprise fillers. These fillers may, for example, adjust the dielectric constant of the polymer element. The reaction mixture preferably contains a filler, for example, a filler having a high dielectric constant, for the purpose of increasing the dielectric constant. Examples thereof are carbon black, graphite, single-walled or multi-walled carbon nanotubes or mixtures thereof. In this context, it is of particular interest that such carbon blacks exhibit surface passivation, so as to actually increase the dielectric constant at low concentrations below the percolation threshold, without leading to an increase in the conductivity of the polymer.

Within the scope of the invention, additives for increasing the dielectric constant and/or for increasing the electrical breakdown field strength can be added even after film formation. This may be achieved, for example, by forming an additional layer (or additional layers), or by, for example, diffusing into the polymeric element so as to infiltrate the polymeric element.

The application of the film-forming composition according to the invention can be achieved using all known application forms: mention may be made, for example, of knife coating, brushing, casting, centrifuging, spraying or extrusion.

In addition, multi-layer applications comprising an optional drying step interposed therebetween are also possible.

The drying and fixing of the reaction mixture can be carried out at temperatures of > 30 ℃ and more preferably at temperatures of > 10 ℃ to < 200 ℃. In this regard, the coated substrate may be run over a hot surface such as a roll. Both application and drying can be carried out discontinuously or continuously. The process is preferably carried out completely continuously.

The polymer element according to the invention may have additional layers. It can be carried out by coating the polymer elements in one or both sides in one layer or in several layers on top of one another, either completely or by planar partial coating.

In particular, suitable as carrier materials for the production of polymer films are glass, release paper (Trennpapier), foils and plastics, from which the polymer films optionally can be easily removed.

The treatment of the individual layers can be effected by casting or by knife coating, which is carried out manually or mechanically. Printing, screen printing, injection molding, spraying, and dipping are also possible processing techniques.

The polymer element according to the invention advantageously exhibits good mechanical strength and high elasticity. In particular, the polymeric component according to the invention may exhibit a maximum stress of ≥ 0.2MPa, in particular ≥ 0.4MPa to ≤ 50MPa, and a maximum elongation of ≥ 250%, in particular ≥ 350%. In addition, the polymer element according to the invention can exhibit a stress (determined according to DIN 53504) of ≥ 0.1MPa to ≤ 1MPa, for example ≥ 0.1MPa to ≤ 0.8MPa, in particular ≥ 0.1MPa to ≤ 0.3MPa, in the range of an elongation in use of ≥ 100% to ≤ 200%. In addition, the polymer elements according to the invention can exhibit an elastic modulus (determined according to DIN EN 1506721-1) of ≥ 0.1MPa to ≤ 10MPa, for example ≥ 0.2MPa to ≤ 5MPa, at a growth rate of 100%.

After crosslinking, the polymer elements according to the invention (in the form of polymer films, polymer foils or polymer coatings) can exhibit a layer thickness of ≥ 0.1 μm to ≤ 1500 μm, for example ≥ 1 μm to ≤ 500 μm, in particular ≥ 5 μm to ≤ 200 μm, preferably ≥ 5 μm to ≤ 50 μm.

The film more advantageously has good electrical properties; this can be determined using breakdown field strength according to ASTM D149, and dielectric constant measurement according to ASTM D150.

For the purpose of assembling the transducer according to the invention, the polymer element according to the invention may be covered on both sides with electrodes, as described in WO 01/06575. The basic structure can be used in a variety of configurations depending on the purpose for which the sensor, actuator and/or generator is produced.

Example (b):

all percentages are by weight unless otherwise noted.

All analytical measurements are based on a temperature of 23 ℃ unless otherwise stated.

The NCO content is determined on a volume basis in accordance with DIN-EN ISO 11909, unless explicitly stated otherwise.

The viscosity is determined by the rotational viscosity method at 23 ℃ in accordance with DIN 53019 using a rotational viscometer manufactured by Anton Paar Germany GmbH, Ostfildern, Germany.

The incorporation of the filler into the dispersion according to the invention was carried out using a SpeedMixer (Hauschild & Co KG, Postfach 4380, germany, model 150FV produced by 59039 Hamm).

The measurement of the layer thickness of the films was carried out using mechanical gauges produced by Heidenhain GmbH, Germany, Postfach 1260, 83292 Traunreut. The samples were measured at three different locations and the average of the representative measurements was taken.

The tensile test was carried out by means of a tensile tester model Zwick, 1455, equipped with a load cell with a total measuring range of 1kN, in accordance with DIN 53504 at a tensile test rate of 50 mm/min. For the sample, a tensile test bar of S2 was used. Each measurement was performed on three similarly prepared samples and the average of the data obtained was used for evaluation purposes. For this purpose, in addition to the tensile strength [ MPa ] and the productivity at break [% ], the stress [ MPa ] at 100% and 200% elongation was also determined.

The determination of the volume resistivity was carried out using a measuring device (electrometer: model 6517A; measuring head: model 8009) manufactured by Keithley Instruments Inc., 28775 Aurora Road, Cleveland, Ohio 44139, Unite States of America with the accompanying program (model 6524: high resistance measurement software). A symmetrical rectangular voltage of +/-50V was applied for 10 cycles at 4 min/cycle and the current was measured. The sample resistance for each voltage cycle was calculated by converting the current value immediately preceding the voltage and was calibrated based on the cycle number. The calibrated values show the measurement of the volume resistivity of the sample.

Dielectric constant measurement according to ASTM D150-98 Using Novocontrol Technologies GmbH&Measuring devices from Co, KG, Oberbacher Stra beta e 9, 56414 Hundsangen, Germany (measuring bridge: Alpha-A Analyzer, measuring head: ZGS Active Sample Cell Test Interface) with a Sample diameter of 20 mm. In this connection, study 10⁷Hz-10^-2The Hz frequency range. For the dielectric constant measurement of the investigated materials, 10 was chosen^-2Real part of dielectric constant in Hz.

The determination of the breakdown field strength according to ASTM D149-97 a was carried out using a high-voltage source of the type LNC 20000-3pos, produced by Heinzinger, Anton-Jakob-Str.4 at 83026 Rosenheim, Germany, and a DKI-specific construction specimen holder (Deutsches Kunststofinstintt, Schlo β gartens. 6 at 64289 Darmstadt, Germany). The sample holder contacts a uniformly thick polymer sample with only a slight mechanical initial load and prevents the operator from touching the voltage. In this device (for the purpose of insulation against breakdown in air, in silicone oil), the polymer foil without a pre-voltage is statically loaded with a gradually increasing voltage until an electrical breakdown through the foil occurs. The measurement results are the voltage [ V/μm ] reached at breakdown, based on the thickness of the polymer foil.

Materials and abbreviations used:

printex 140 Degussa GmbH, Wei β frauentr.9, 60311 Frankfurt am Main, product of Germany, mean particle size 29nm, BET surface area 90m²Per g, pH 4.5 (all data according to Degussa data sheet)

H ä rter DT substituted aromatic diamine having an NH equivalent value of about 90, an amine value of about 630mg KOH/g, a viscosity of about 200mPas

Technical application test

Example 1 (prepolymer a-1):

840g of Hexamethylene Diisocyanate (HDI) and 0.08g of zinc octoate were added to a 4 l four-necked flask. Within one hour, 1000g of difunctional polypropylene glycol polyether with a molar mass of 8000g/mol are added at 80 ℃ and stirring is continued for 1 hour. Then, 0.3g of benzoyl chloride was added. Subsequently, excess HDI was removed by thin layer distillation, distillation at 130 ℃ and 0.1 torr. A prepolymer having an NCO content of 1.80% was obtained.

Example 2 (prepolymer a-2):

840g of Toluene Diisocyanate (TDI) and 0.08g of zinc octoate were added to a 4 liter four-necked flask. Within one hour, 1000g of difunctional polypropylene glycol polyether with a molar mass of 8000g/mol are added at 80 ℃ and stirring is continued for 1 hour. Then, 0.3g of benzoyl chloride was added. Subsequently, the excess TDI was distilled off by thin layer distillation at 130 ℃ and 0.1 torr. A prepolymer having an NCO content of 1.66% was obtained.

Example 3 (aspartic acid ester B)

To 2mol of diethyl maleate, 1mol of 2-methyl-1, 5-diaminopentane was slowly added dropwise under a nitrogen atmosphere in such a manner that the reaction temperature did not exceed 60 ℃. Heating at 60 ℃ is then carried out for such a long time: until diethyl maleate was no longer detectable in the reaction mixture.

Example 4 (according to the invention)

The raw materials used were not degassed separately. The required amount of 2g of aspartate B of example 3 and 20.79g of prepolymer A-2 of example 2 were weighed into a polypropylene beaker and mixed at 3000 rpm for 2s at a Speedmixer. From the reaction mixture which is still in the liquid state, a film having a wet film thickness of 1mm is drawn off by hand on a glass plate. After production, all membranes were dried in a drying oven at 80 ℃ overnight and then annealed at 120 ℃ for 5 min. After annealing, the film can be easily separated from the glass plate.

Example 5 (according to the invention)

The raw materials used were not degassed separately. The required amount of 2g H ä rter DT and 71.99g of prepolymer A-2 of example 2 were weighed into a polypropylene beaker and mixed at 3000 rpm for 2s at a Speedmixer. From the reaction mixture which is still in the liquid state, a film having a wet film thickness of 1mm is drawn off by hand on a glass plate. After production, all membranes were dried in a drying oven at 80 ℃ overnight and then annealed at 120 ℃ for 5 min. After annealing, the film can be easily separated from the glass plate.

Example 6 (according to the invention)

The raw materials used were not degassed separately. The desired amounts of 0.5g H ä rter DT, 0.5g of the aspartate B of example 3, and 18.07g of the prepolymer A-2 of example 2 were weighed into a polypropylene beaker and mixed at 3000 rpm for 2 seconds in a Speedmixer. From the reaction mixture which is still in the liquid state, a film having a wet film thickness of 1mm is drawn off by hand on a glass plate. After production, all membranes were dried in a drying oven at 100 ℃ overnight and then annealed at 120 ℃ for 5 min. After annealing, the film can be easily separated from the glass plate.

Example 7 (comparative example)

All liquid feeds were carefully degassed in a three stage process under argon and the carbon black was screened using a 125 μm sieve. 10g of Terathane 650 (INVISTA GmbH, D-65795 Hatterheim, polyTHF having a molar mass Mn of 650) and 0.596g of carbon black (product of Ketjenblack EC 300J, Akzo Nobel AG) were weighed into a 60ml disposable mixing vessel (APM-Technika AG, order number 1033152) and mixed in a Speedmixer (product of APM-Technika AG, 9435 Heerbrugg, Switzerland; sales D: Hauschild; model DAC 150 FVZ) at 3000 rpm for 3min to form a homogeneous paste. 0.005g of dibutyltin dilaurate (Metacure T-12, Air Products and Chemicals, Inc.) and 6.06g of isocyanate N3300 (isocyanurate trimer of HDI; product of Bayer MaterialScience AG) were subsequently weighed and mixed in a Speedmixer at 3000 revolutions per minute for 1 min. The reaction paste was poured onto a glass plate and drawn to a 1mm wet film thickness with a spatula to form a uniform film with a solids content of 2%. The film was then annealed at 80 ℃ for 16 h.

Example 8 (comparative example)

All liquid feeds were carefully degassed under argon in a three-stage process. 10g of Terathane 650 (INVISTA GmbH, D-65795 Hatterheim, mol. mass Mn 650 of polyTHF) were weighed into a 60ml disposable mixing vessel (APM-Technika AG, order number 1033152). 0.005g of dibutyltin dilaurate (Metacure L-12, Air Products and Chemicals, Inc.) and 6.06g of isocyanate N3300 (isocyanurate trimer of HDI; product of Bayer MaterialScience AG) were subsequently weighed and mixed in a Speedmixer at 3000 revolutions per minute for 1 min. The reaction paste was poured onto a glass plate and drawn to a 1mm wet film thickness with a spatula to form a uniform film. The film was then annealed at 80 ℃ for 16 h.

Example 9 (comparative example)

All liquid feeds were carefully degassed in a three stage process under argon and the carbon black was screened using a 125 μm sieve. 10g of Terathane 650 (INVISTA GmbH, 65795 Hatterheim, Germany, polyTHF having a molar mass Mn of 650) and 0.536g of Printex 140 were weighed into a 60ml disposable mixing vessel (APM-Technika AG, order number 1033152) and mixed in a Speedmixer (APM-Technika AG, 9435 Heerbrugg, product of Switzerland; sales D: Hauschild; model DAC 150 FVZ) at 3000 rpm for 3min to form a homogeneous paste. 0.005g of dibutyltin dilaurate (Metacure T-12, Air Products and Chemicals, Inc.) and 6.06g of isocyanate N3300 (isocyanurate trimer of HDI; product of Bayer MaterialScience AG) were subsequently weighed and mixed in a Speedmixer at 3000 revolutions per minute for 1 min. The reaction paste was poured onto a glass plate and drawn to a 1mm wet film thickness with a spatula to form a uniform film with a solids content of 2%. The film was then annealed at 80 ℃ for 16 h.

Table 1: properties of the films produced in examples 4 to 9

Examples	Elongation at break	Tensile strength	Stress at 100% elongation	Stress at 200% elongation	Volume resistivity	Dielectric constant	Breakdown field strength
									[%]	[MPa]	[MPa]	[MPa]	[Ohm cm]		[V/μm]]
4*	288	1.1	0.47	0.48	1.9 ∙ 1011	25.0	25
								5*	253	3.8	1.60	3.00	2.6 ∙ 1012	9.0	29
6*	316	2.1	0.87	1.36	1.9 ∙ 1011	36.6	32
								7	57	3.4	-	-	6.4 ∙ 1011	28.4	7
8	44	1.7	-	-	2.7 ∙ 1012	18.6	11
								9	46	1.6	-	-	7.9 ∙ 1011	550.0	5

According to the invention

It is clear that in tests, the membrane according to the invention offers significant advantages compared to the prior art. In particular, these advantages can be further enhanced for the films of the present invention formed from an aspartate and a polyisocyanate prepolymer.

With the films of the invention, particular advantages are achieved in terms of a high dielectric constant, at the same time as a very high breakdown field strength in the unstretched state, in particular in the particularly preferred embodiment of the films of the invention formed from an aspartate and a polyisocyanate prepolymer, and excellent mechanical properties, such as high elasticity, high elongation at break, a suitable stress-elongation curve with low stress at moderate elongations in the range of use of the application. In particular, in addition to a high dielectric constant, in a particularly preferred embodiment of the films of the invention formed from aspartate and polyisocyanate prepolymers, the elongation at break and the tensile behavior can be further enhanced in the unstretched state, with very high breakdown field strengths. In the comparative examples, since these materials had already torn at 40% to 60% elongation, the stress at 100% elongation or 200% elongation could not be measured.

Claims (12)

1. An electromechanical transducer having at least two electrodes and at least one polymer element, wherein the polymer element is arranged between two electrodes,

is characterized in that

The polymeric component is obtainable from a reaction mixture comprising:

A) a polyisocyanate or polyisocyanate prepolymer or a mixture thereof, and

B) a compound having at least two isocyanate-reactive amino groups.

2. Transducer according to claim 1, characterized in that the electromechanical transducer is a sensor and/or an actuator and/or a generator.

3. Transducer according to claim 1 or 2, characterized in that the composition

A) Is a polyisocyanate containing isocyanurate and/or urethane groups, or a polyisocyanate prepolymer containing isocyanurate and/or urethane groups, or a mixture thereof.

4. Transducer according to one of claims 1-3, characterized in that the composition

B) Is an amino-functional aspartate.

5. Transducer according to one of claims 1-4, characterized in that the composition

B) An amino-functional aspartate of the general formula (I):

wherein

X represents an n-valent organic residue which is obtained by removing at least two primary amino groups of an n-membered amine,

R₁、R₂represent identical or different organic radicals which do not contain Zerewitinoff active hydrogen, and

n represents an integer of 2 or more.

6. Transducer according to one of claims 1-5, characterized in that the composition

B) An amino-functional aspartate of the general formula (I):

wherein

X represents a divalent organic residue obtained by removing an amino group from 1, 4-diaminobutane, 1, 6-diaminohexane, 2-methyl-1, 5-diaminopentane, 2, 4-or 2,4, 4-trimethyl-1, 6-diaminohexane,

R₁、R₂in each case independently of one another, a linear or branched alkyl radical having from 1 to 10 carbon atoms, and

n represents 2.

7. Method for producing an electromechanical transducer according to one of claims 1 to 6, wherein

-providing at least two electrodes, and

-providing a polymeric element by converting a reaction mixture comprising:

A) a polyisocyanate or polyisocyanate prepolymer or a mixture thereof, and

B) a compound having at least two isocyanate-reactive amino groups,

and

-arranging the polymer element between two electrodes.

8. A method according to claim 7, characterized in that the polymeric element is provided by applying the reaction mixture to at least one of the electrodes.

9. The method according to claim 7 or 8, characterized in that the reaction mixture is dried and/or annealed.

10. Use of a polymeric component obtainable from a reaction mixture comprising:

A) a polyisocyanate or polyisocyanate prepolymer or a mixture thereof, and

B) a compound having at least two isocyanate-reactive amino groups.

11. Electronic and/or electrical device comprising an electromechanical transducer according to one of the claims 1 to 6.

12. Use of an electromechanical transducer according to one of the claims 1 to 6 in an electrical and/or electrical device.