DE102019123894A1 - Production of an elastic dielectric from nitrile butadiene rubber or a derivative thereof - Google Patents

Abstract

A method is described for producing an elastic dielectric (130) for a dielectric device (100), in particular a dielectric actuator and / or a dielectric sensor. The method comprises: i) providing a base (210) which has a base surface (212), ii) forming an elastomer layer (230) of uncured elastomer material on the base surface (212), the elastomer material comprising a copolymer, and wherein the copolymer nitrile-butadiene rubber (NBR) or a derivative thereof, and iii) at least partial curing, in particular crosslinking, of the elastomer layer (230) for providing the elastic dielectric (130), the elastic dielectric (130) having a thickness ( d) of 100 µm or less.

Description

The invention relates to a method for producing an elastic dielectric for a dielectric device (in particular a dielectric actuator and / or a dielectric sensor). The invention also relates to a method for producing a dielectric device. The invention also relates to a dielectric device. The invention also relates to the use of an (elastic) copolymer in a dielectric device.

The invention can thus relate to the technical field of dielectric devices. In particular, the invention can relate to the technical field of dielectric (elastomer) actuators and / or dielectric (elastomer) sensors. More particularly, the invention can relate to the technical field of the use of elastic copolymers (in particular based on NBR or a derivative thereof) with regard to dielectric devices.

A dielectric device, such as a dielectric (elastomer) actuator (DEA), a dielectric (elastomer) sensor (DES) or a mixed form (DEAS), is basically constructed like a flexible electrostatic capacitor. A (with regard to electromechanical aspects essentially) passive elastomer layer (or a polymer layer) is clamped between two electrode plates. When an electrical voltage U is applied (i.e. in the operating mode), the opposing electrode plates attract each other due to the electrostatic pressure (p _el ). The incompressible elastomer layer is then compressed in the vertical direction and expands in the lateral direction (surface expansion). The electrostatic pressure that causes the deformation is determined by the dielectric constant, the dielectric constant, and the thickness of the material as well as the voltage applied.

The equivalent electromechanical pressure p _eq occurring in the operating mode is twice as large as the electrostatic pressure p _el and can be calculated as: p _eq = ε0 * ε _r * (U ² / z ² ), where ε _{0 is} the permittivity of the vacuum, ε _{r is} the dielectric constant and z is the layer thickness of the elastomer layer.

The movement is thus generated by the electrostatic forces that act on the elastomer layer between two electrode plates. In one example, a dielectric actuator reaches an elongation of up to 20% at a field strength of 30 V / µm. Usual unidirectional expansions of dielectric actuators are e.g. in the range 10 to 35%, maximum values up to 300%.

Since the elastomer layer is almost incompressible, the volume remains in principle constant during the deformation. When the voltage is reduced, the excess charges flow away via the voltage source, so that the elastomer layer returns to its original shape and can exert forces due to the stored elastic energy.

This principle can be used both as an actuator and as a sensor and offers a number of promising technical application possibilities. Particular advantages of these dielectric devices can be that they can be light, flexible and noiseless and also cause low material costs. However, these advantageous possible applications are currently opposed to unresolved issues relating to production and reliability.

For the particularly large-volume industrial production of dielectric devices, a high degree of stability and aging resistance is desired for the dielectric. In addition, a small thickness of the dielectric is desirable for advantageous operation. Known lamination techniques are no longer the method of choice here because the tension in the y-direction required for fabrication results in too great differences in properties between the main directions of extension when the thickness falls below a certain minimum. The prior separate crosslinking in the lamination process also makes the desired adhesion on the (manufacturing) base (in particular an electrode) more difficult, since almost every possibility of a covalent bond has already been anticipated. Furthermore, the creation of a displacement space for the dielectric is desired or necessary. This is in order to prevent (or limit) that a lateral (in x- and y-direction) extrusion of dielectric material takes place during compression during operation. The provision of displacement space is quite challenging when using elastic polymers as dielectric material, in particular because of the crosslinking speed and the pronounced adhesion.

It is an object of the present invention to efficiently manufacture an elastic dielectric for a dielectric device, so that advantageous operation (high sensitivity, high stability, and age resistance) is enabled.

This object is achieved by the subjects according to the independent patent claims. Preferred configurations emerge from the dependent claims.

According to one aspect of the present invention, a method of making a elastic dielectric for a dielectric device (in particular a dielectric (elastomer) actuator and / or a dielectric (elastomer) sensor) described. The method comprises: i) providing a base (in particular a base material, e.g. electrode material or a carrier film) which has a base surface, and ii) forming an elastomer layer from uncured (in particular liquid) elastomer material on the base surface. The elastomer material has an (elastic) copolymer which, in particular, has copolymer nitrile butadiene rubber (NBR) or a derivative (or a substance derived therefrom (e.g. HNBR)) thereof, and iii) at least partial curing (especially crosslinking) of the Elastomer layer for providing the elastic dielectric. Here, the elastic dielectric has a thickness of 200 μm (in particular 100 μm) or less.

According to a further aspect of the present invention, a method for producing a dielectric device (in particular a dielectric actuator and / or a dielectric sensor) is described. The method comprises: i) providing an elastic dielectric as described above, ii) applying electrode material (in particular onto the as yet uncured elastomer material), and iii) forming a (second) electrode from the electrode material. This in particular in such a way that the electrode adheres to the dielectric (e.g. through structuring / perforations on the dielectric / electrode surface).

According to a further aspect of the present invention, a dielectric device (in particular a dielectric actuator and / or a dielectric sensor) is described. The device has: i) a first electrode, ii) a second electrode which is arranged opposite the first electrode, and iii) an elastic dielectric which is arranged between the first electrode and the second electrode (in particular wherein the dielectric is as above described is manufactured). The elastic dielectric has a copolymer, which in turn has nitrile-butadiene rubber or a derivative thereof. In addition, the elastic dielectric has a thickness of 200 μm (in particular 100 μm) or less.

According to a further aspect of the present invention, a copolymer is used in an elastic dielectric of a dielectric device (in particular a dielectric device which is designed as a stack system (or stack actuator and / or stack sensor)). The copolymer here has: i) a first monomer unit, which is represented by the following formula (F1): - [CH ₂ -C (R ₁ ) H] - (F1). Here R1 is selected from: CN, CO (OH), and CO (NH ₂ ), and ii) a second monomer unit, which is represented by the following formula (F2): - [C (R ₂ ) H- (XY) -CH ₂ ] - (F2). Here R2 is selected from: H, and CH ₃ . Furthermore, X is selected from: - CH =, -CH ₂ -, -C (CH ₃ ) =, and -C (CH ₃ ) H-, and Y is selected from: -CH =, and - CH ₂ -.

In the context of this document, the term “dielectric (elastomer) actuator (DEA)” can in particular be understood to mean an actuator which consists of two electrodes and an intermediate spring-based or elasticity-based dielectric spacer, in particular made of elastomer material. The actuator effect is understood through the interplay of the spring forces between the electrodes (plates) on the one hand and the Coulombic attraction between the electrodes on the other.

In the context of this document, the term “dielectric (elastomer) sensor (DES)” can be understood to mean in particular a sensor which consists of two electrodes and an intermediate spring-based or elasticity-based dielectric spacer, in particular made of elastomer material. The sensory measured variable is obtained from the capacitance determined by the electrode spacing or from the change in capacitance that occurs when the electrode spacing changes.

In the context of this document, the term “dielectric (elastomer) actuator and sensor (DEAS)” can be understood to mean, in particular, a combination of the principles of DEA and DES in one system. Features that apply to a DEA can also apply to a DES and vice versa.

In the context of this document, the described coordinate system can be understood to mean that the directions x and y (as main directions of extent) span the surface of an electrode and the height direction z is aligned along the distance between two opposing (parallel aligned) electrodes. In one embodiment with regard to a manufacturing process, x can correspond to the width (cross-direction (CD) in a reel-to-reel production) and y to the processing direction (machine direction (MD) in a reel-to-reel production).

In the context of this document, the term “electrode” can be understood in particular as an electron conductor which is connected to a counter electrode (then referred to as anode and cathode, or as a plus pole and a minus pole) via a (dielectric) medium located between the two electrodes Interaction stands. In this way, an electric field can be generated between the electrodes. An electrode can be a Have a “functional (active) area” or consist entirely of the functional area. The functional area is electrically conductive (in particular comprising a metal) and can thus form the active part of the electrode, which interacts electrically with the counter-electrode. Furthermore, an electrode can have an electrically non-conductive area, for example a carrier material, to which the functional area (for example as a metal foil) is applied. Furthermore, an electrode can have an (electrically conductive) contact area to which contact can be made with the electrode or to which a voltage can be applied. According to one embodiment, the metal of the electrode (or of the functional area) is at least one from the group consisting of: Ag, Al, Au, Be, Cr, Cu, Fe, In, Mg, Mo, Ni, Pb, Pd , Pt, Rh, Sb, Sn, Ti, Zn, and alloys thereof. Alloy components below 2% by weight can also consist of other metals (e.g. Si, As, etc.). Alloys can include, for example: iron alloy, brass, bronze, stainless steel, aluminum, etc. In order to avoid incompatibilities (for example copper on polymer), multilayer metal structures are also possible.

In the context of this document, the term “dielectric” can in particular denote any material (or substance) in which charge carriers are essentially not freely movable. This results in an electrically weakly conductive to non-conductive property. A dielectric can, for example, be a polymer, in particular an elastomer. A dielectric cannot be a metal. With respect to a dielectric device, the dielectric can be a resilient dielectric such as a dielectric polymer (DE). Dielectric polymers, along with piezoelectric polymers and electrostrictive polymers, are also known as electroactive polymers (EAP).

In one embodiment, to produce a dielectric, material of an elastic polymer (in particular elastomer material) is applied in uncured form (in particular on an electrode) and then cured. In this document, the term “curing” can be understood to mean, in particular, a large number of different forms of material hardening or an increase in material viscosity. During a curing process, a material can transition from a first state to a second state, the material being more solid in the second state than in the first state. Furthermore, the viscosity of the first state can be significantly lower than the viscosity of the second state. Curing can include, for example, at least one of the following processes: crosslinking, thermal solidification processes, drying reactions, gelling processes.In one example, a non-cured, at least partially liquid elastomer material (e.g. in a solvent or a suspension medium) is applied to an electrode (or a carrier film) applied. During curing (e.g. by drying the solvent / suspension medium and / or crosslinking the elastomer material, in particular specifically controlled crosslinking e.g. by means of UV radiation), the elastomer material can have an essentially more solid form and / or have a higher viscosity than the non- cured elastomer material. In particular, the cured elastomer material can be used as a dielectric.

Curing can be carried out, for example, by means of a crosslinking reaction and / or film formation by drying from solution and / or film formation by drying from a dispersion. With regard to the crosslinking, this can be carried out with at least one of the following processes: i) radiation crosslinking (preferably by UV radiation), ii) electron crosslinking (e.g. by an electron beam source), iii) thermally initiated radical crosslinking, iv) thermal sulfur crosslinking, v) peroxide initiated radical crosslinking.

In the context of this document, the term "elasticity" can in particular denote the property of a material to change its shape (deformation) under the action of force (e.g. pressure) and to return to its original shape when the force is no longer present. Linear deformations can be described using Hooke's law (linear elastic behavior, e.g. spring). On the other hand, non-linear elastic deformation occurs, for example, in rubber. The elasticity can be described, for example, using the modulus of elasticity. This is a material parameter that describes the proportional relationship between stress and strain (sweg) during the deformation of a solid body in the case of linear-elastic behavior. The modulus of elasticity can be viewed as a constant of proportionality in Hooke's law. Correspondingly, for example, the modulus of elasticity can be a property of elasticity. In the case of anisotropic materials, the modulus of elasticity can be direction-dependent, so that such materials can have two elastic properties that differ from one another.

In the context of this document, the term “elastic copolymer” can in particular denote a polymer which has two or more different monomer units (in contrast to homopolymers) and has an elasticity (see definition above). A copolymer can include both random copolymers, gradient copolymers, alternating copolymers, block / segment copolymers, and graft copolymers. An example of a copolymer is a nitrile rubber such as nitrile Butadiene rubber (NBR) or a derivative thereof. In this document, the term “NBR or a derivative thereof” can designate a plurality of elastic copolymers whose monomer units are based on ethane (two carbon atoms) and butane (four carbon atoms). The first monomer unit can be, for example, acrylonitrile. The second monomer unit can be butadiene, for example. The copolymer can therefore be, for example, acrylonitrile-butadiene (AB). Further examples are described below. In an exemplary embodiment, the viscosity of NBR in the unvulcanized state can be: Mooney viscosity (4 + 1) according to DIN 53523 / ISO 289 : 29 Mooney units, shear viscosity: 2.98 * 10 ³ Pa * s at a shear rate of 100 s ^-1 .

In the context of this document, the term “base” can in particular denote any object which has a base area on which an elastic dielectric can be produced. In a preferred example, the base is a base material, such as electrode material, which is incorporated into the dielectric after the manufacturing process (e.g., for making a dielectric device). In another example, the base is a carrier material (in particular a carrier film) on which the dielectric can be provided. For example, in a reel-to-reel process, a carrier film can be unrolled from a roll and rolled onto another roll. Dielectric material can be deposited on the carrier film during the transport path. The carrier material is preferably removable from the dielectric and can be reused.

According to an exemplary embodiment, the invention can be based on the idea that an elastic dielectric for a dielectric device on the one hand can be produced particularly efficiently and on the other hand enables advantageous operation (of the dielectric device) if the elastomer material is an elastic copolymer, which is NBR or a derivative thereof, is provided in a particularly thin thickness (in particular 100 µm or less). The small thickness enables efficient operation. By setting a particularly thin layer thickness, a particularly advantageous elastic dielectric can be provided, the thickness of which is constant, homogeneous and thin. This can reduce field shifts and increase the sensitivity (e.g. of a dielectric actuator / sensor). In the case of an elastic copolymer such as NBR, in particular, it is a challenge to enable such a small layer thickness. At the same time, however, the robust NBR copolymer or a derivative thereof results in a high level of stability and age resistance, while at the same time this has particularly desirable elasticity properties.

1. a) Das Relaxationsverhalten nach Auflösen der mechanischen äußeren Belastung (durch Kompression oder Expansion bei der Verwendung als DES oder durch elektrostatische Anziehungseffekte bei der Verwendung als DEA) kann sowohl über die gesamte Einsatzamplitude, als auch den gesamten Einsatzzeitraum und unabhängig von der DEAS-Frequenz möglichst konstant bleiben. Dieses Relaxationsverhalten in Korrelation mit der materialspezifischen Elastizität (Dehnungsverhalten) des Elastomers beruht im Wesentlichen auf einer kontrollierten (steuerbaren) Netzwerkdichte der physikalischen oder chemischen Vernetzung.
2. b) Eine Temperaturbeständigkeit über den gesamten Einsatzbereich, beispielsweise - 40°C bis +120°C (insbesondere im Automotivbereich), wobei diese Beständigkeit sowohl den Bereich der Alterung, als auch der Relaxationskonstanz umfassen kann.
3. c) Die Dielektrizitätskonstante kann die üblichen, für Elastomere gewöhnlichen Werte erreichen, und nach oben erweitern, ohne die mechanischen Eigenschaften (z.B. Elastizitätsminderung durch Permittivität-steigernde Additive wie BaTiO₃ zu mindern) und/oder die dielektrischen Eigenschaften (z.B. Durchschlagsfestigkeit) zu verschlechtern.

The following advantages can also result from the use of NBR or its derivatives:

1. a) The relaxation behavior after dissolving the mechanical external load (through compression or expansion when used as a DES or through electrostatic attraction effects when used as a DEA) can be as possible over the entire deployment amplitude as well as the entire deployment period and independently of the DEAS frequency stay constant. This relaxation behavior in correlation with the material-specific elasticity (elongation behavior) of the elastomer is essentially based on a controlled (controllable) network density of the physical or chemical crosslinking.
2. b) A temperature resistance over the entire range of use, for example -40 ° C to + 120 ° C (especially in the automotive sector), this resistance being able to include both aging and relaxation constancy.
3. c) The dielectric constant can reach the usual values for elastomers and expand upwards without impairing the mechanical properties (e.g. reducing elasticity by means of permittivity-increasing additives such as BaTiO ₃ ) and / or the dielectric properties (e.g. dielectric strength).

In other words, it was surprisingly recognized that the elastic copolymer NBR (or a derivative thereof) with its proven robust and elastic properties can be used particularly advantageously in a dielectric device if additional measures are taken to enable a particularly thin layer thickness.

According to one embodiment, the ratio of the ethane (nitrile) monomer unit (from NBR), or a derivative thereof, and the butane (butadiene) monomer unit (from NBR), or a derivative thereof, is in the range 1: 1 to 1: 5. This enables advantageous properties for efficient operation (e.g. with regard to elasticity) to be achieved.

In one example, the following results for the ratio n (first monomer unit) to m (second monomer unit): i) the lower m, the higher the temperature resistance, the higher the permittivity, the lower the gas permeability (a property that is important for a design variant with pores, see below), and ii) the higher m, the more advantageous the relaxation behavior, the greater the elongation at break, and the lower the modulus of elasticity.

According to a further exemplary embodiment, the elastic copolymer has: i) a first monomer unit, which is represented by the following formula (F1): - [CH ₂ -C (R ₁ ) H] - (F1). Here, R1 is selected from: CN, CO (OH), and CO (NH ₂ ) (in particular, CN is in the range from 90 to 100% and COOH / CONH ₂ in the range from 0 to 10%), and ii) a second monomer unit represented by the following formula (F2): - [C (R ₂ ) H- (XY) -CH ₂ ] - (F2). Here R2 is selected from: H, and CH ₃ . Furthermore, X is selected from: -CH =, -CH ₂ -, -C (CH ₃ ) =, and -C (CH ₃ ) H-, and Y is selected from: -CH =, and -CH ₂ -. This elastic copolymer (with the substitutions mentioned) can be referred to as “NBR or a derivative thereof”. The elastic copolymer described has proven to be particularly advantageous (in particular elasticity, stability) with regard to the operation of a dielectric device.

• Die Spannungsfestigkeit kann bei > 50 KV/mm, insbesondere > 80 KV/mm liegen. Eine Permittivität von > 10, insbesondere > 12, weiter insbesondere > 15, kann besonders vorteilhaft sein. Elastizitätsmodul < 600 kPa und/oder Reißdehnung > 250%, insbesondere > 350%, kann ebenfalls vorteilhaft sein.

The elastic copolymer described can result in the following special properties:

• The dielectric strength can be> 50 KV / mm, in particular> 80 KV / mm. A permittivity of> 10, in particular> 12, further in particular> 15, can be particularly advantageous. Modulus of elasticity <600 kPa and / or elongation at break> 250%, in particular> 350%, can also be advantageous.

1. a) X/Y: i) Vermeidung/Eliminierung von Doppelbindungen steigert die Wärmebeständigkeit, verändert das Vernetzungsverhalten (z.B. keine Schwefelvernetzung möglich), und ii) Methylgruppe an X erhöht die Reißdehnung, vermindert den Elastizitätsmodul.
2. b) R2 als Methylgruppe: erhöht den Elastizitätsmodul, vermindert Relaxation.
3. c) R1 als Nitrilgruppe: erhöht die Permittivität ohne die Durchschlagsfestigkeit zu vermindern.
4. d) R1 als Carbonsäuregruppe: ähnliche Permittivität wie die Nitrilgruppe, jedoch Verminderung der Durchschlagsfestigkeit, und (bereits bei geringem Anteil) Haftungserhöhung auf Metalloberflächen, vorteilhafterweise also (Metall-) Elektroden oder (Metall-beschichtete) Trägermaterialien (Folien).
5. e) R2 als Amidgruppe (CONH₂): ähnliche Permittivität wie die Nitrilgruppe und die Carbonsäuregruppe COOH, fördert aber Gelstrukturen, insbesondere mit polaren Lösemitteln (z.B. Ether, Ester etc.) in der Verarbeitungsphase und damit die Thixotropie in der Verarbeitungsphase bzw. bei Mitvernetzung geeigneter Lösungsmittel durch Fixierung der Gelstrukturen die mechanischen Eigenschaften (insbesondere Erhöhung der Elastizität und Senkung des Elastizitätsmoduls).

Furthermore, the following correlations were found in one embodiment:

1. a) X / Y: i) Avoidance / elimination of double bonds increases the heat resistance, changes the crosslinking behavior (eg no sulfur crosslinking possible), and ii) the methyl group on X increases the elongation at break, reduces the modulus of elasticity.
2. b) R2 as a methyl group: increases the modulus of elasticity, reduces relaxation.
3. c) R1 as a nitrile group: increases the permittivity without reducing the dielectric strength.
4. d) R1 as a carboxylic acid group: similar permittivity to the nitrile group, but a reduction in dielectric strength and (even with a small proportion) increased adhesion to metal surfaces, advantageously (metal) electrodes or (metal-coated) carrier materials (foils).
5. e) R2 as an amide group (CONH ₂ ): similar permittivity as the nitrile group and the carboxylic acid group COOH, but promotes gel structures, especially with polar solvents (e.g. ethers, esters, etc.) in the processing phase and thus the thixotropy in the processing phase or with crosslinking suitable solvents by fixing the gel structures the mechanical properties (in particular increasing the elasticity and lowering the modulus of elasticity).

In one example, the variations described have in common that they (even in the crosslinked state) do not change to a shear-induced crystallinity (e.g. in the event of a spontaneous, operationally typical load), as can be observed in particular with natural rubber (NR). In one example, this can be essential for the uniformity of the actuator / sensor properties.

In a further exemplary embodiment, the ratio of the first monomer unit to the second monomer unit is in the range 1: 1 to 4 (in particular 1: 2 or 3). In another exemplary embodiment, the ratio of the first monomer unit to the second monomer unit is in the range 2: 2 to 10 (in particular 2: 4 to 8).

In a further embodiment, when X and Y are each -C (H) = and / or -C (CH3) =, 50% or more of the double bonds between X and Y are in the cis configuration in the elastic copolymer.

In a further exemplary embodiment, the method further comprises: at least partial creation of structures (and / or perforations) on the surface of the elastomer layer (this in particular during the at least partial curing, but is also possible on the essentially solid dielectric). This has the advantage that displacement space can be provided in a simple and yet efficient manner. In addition, adhesion of the elastomer material to a base material can be improved.

By providing a displacement space for dielectric material during operation of the dielectric device, the lateral squeezing out of dielectric material can be prevented / reduced. In particular with an elastic copolymer such as NBR, it is a challenge to provide a suitable displacement space within the crosslinking period.

In the context of this document, the term “structuring” can be understood to mean in particular any structure of a base material or an electrode that is not planar with the surface (e.g. in the case of a plate-shaped electrode) of the electrode. In other words, the structure is oriented in a height direction (z) which is perpendicular to the two main directions of extension (x, y) of the electrode (surface). Structures can be bulges, for example.

The term “perforations” can refer to any opening in the base material or an electrode. A perforation can be designed as a slot, aperture, or recess, for example. Such a perforation can provide space for displaced elastic dielectric.

In one example, the base material (or the base surface) is mechanically deformed before the elastomer material is applied, e.g. structured or perforated (e.g. using a plasma process). This can improve the adhesion (e.g. if liquid elastomer material flows into the structures and is then cured) and / or a displacement space for the (vertical) displacement movement of the elastomer can be created.

According to a further exemplary embodiment, the dielectric device is configured such that during operation of the device, when the dielectric is compressed by the first electrode and the second electrode, material of the compressed dielectric is at least partially pressed into the structures (and / or perforations). In particular, the majority of structures are at least partially deformed here. A particularly efficient areal expansion of the dielectric can thereby be made possible, so that the dielectric device can be operated in a particularly advantageous manner.

The electrode (or the functional area) can form temporary depot locations (cavities) by means of the structuring (in particular bulges), which can accommodate the excess material of the elastic dielectric when the dielectric device is put into operation. In particular, an electrode that is applied very thinly to a structured dielectric can be embedded together with the latter in the provided alternative depots. If, for example, a structuring makes up a cavity volume of 5% to 20% of the dielectric volume, the displaced mass in the operating state (activated state) of the dielectric device can push itself into precisely these cavities (including electrode material).

In particular, the structuring can be carried out by means of a structuring agent. The structuring agent can be a tool such as a roller. Furthermore, the structuring agent can also be the surface of the base if it is already structured.

In one embodiment, the base material (or the electrode) is either i) brought into a shape which forms spaces into which the (liquid) elastomer material does not flow due to its wetting behavior (alternatively, the base material can also be partially treated in such a way that the wetting angle to the liquid elastomer material is such that an air bubble is formed) and / or ii) is provided with perforations (which are also not wetted).

In one example, microscaline nickel coatings on substrates (e.g. steel) can allow a suitable relief layer to be created on the base. This enables the mechanical design of molds, impression plates / embossing plates or rollers / cylinders (this is particularly suitable for reel-to-reel production). This relief layer is provided in a suitable manner (e.g. between two rollers, for example a flat roller on the carrier film side and a structured roller on the liquid side (uncured elastomer material)).

In another example, other shaping processes are used to produce a corresponding impression form (e.g. 3D printing, etching, embossing, punching, lasers, etc.). A variety of materials are also suitable for the structuring form (e.g. plastics, metals, glasses, etc.).

According to a further exemplary embodiment, the majority of the structuring extend by 100 μm or less (in particular 10 μm or less) in a height direction (z) which is oriented perpendicular to the main extension directions (x, y) of the elastic dielectric. This can provide a particularly effective displacement or adhesion mediation.

According to a further exemplary embodiment, the elastic dielectric has a thickness ( d ) of 70 µm or less (particularly 20 µm or less, more particularly 5 µm or less). As a result, the advantages of a small thickness described above can be expressed in a particularly desirable manner.

According to a further exemplary embodiment, the base has a base material. In particular, the base material is part of an electrode, and in particular the base area is an electrically conductive (in particular metallic) functional area of the electrode. This has the advantage that the elastic dielectric can be provided directly on an electrode, as a result of which a dielectric device can be produced quickly and efficiently.

An electrode can have a “functional (active) area” or consist entirely of the functional area. The functional area is electrically conductive (in particular comprising a metal) and can thus form the active part of the electrode, which interacts electrically with a counter-electrode. The functional one The area can have the base area, so that the dielectric can be deposited directly at the intended position.

According to a further exemplary embodiment, the base (or the electrode) has a thickness of 50 μm or less. This has the advantage that a particularly thin dielectric device can be provided, but the base material is still robust enough to stabilize the deposition of the dielectric. In particular in connection with dielectric devices such as actuators or sensors, small thicknesses can be particularly advantageous (e.g. with regard to sensitivity). The electrode can have a total thickness (e.g. electrically conductive material and carrier material together) of less than 50 micrometers. If the thickness is too great, in one example the electrode thickness would be too great compared to the dielectric thickness, so that the desired actuator or sensor sensitivities are reduced too much.

According to a further exemplary embodiment, the electrode is a multilayer electrode which has a carrier material, in particular a polymer. Here, the functional area is applied, in particular vapor-deposited, to the carrier material. This can have the advantage that the electrode can be constructed in a flexible and / or stable manner.

In one embodiment, a metallic (conductive) coating is applied to a carrier material to produce the electrode. The carrier material can be, for example, an insulating fabric and / or a fleece. The coating thickness can be smaller or very much smaller than the thickness of the insulating carrier material. The structuring (e.g. as openings, movement zones, displacement space) can be given by an inherent, structural structure of the carrier material. In a further exemplary embodiment, the electrode consists of a conductive fleece and / or fabric and / or a metallic membrane which is coated with an insulator or at least in direct contact with the insulator. According to a further exemplary embodiment, the electrode has a multilayer structure. For example, this layered structure can consist of different materials, in particular of different metals. Electrically insulating carrier material can be mechanically or electrically bridged within the dielectric device via a bridging structure in order to contact the functional area.

The carrier material can advantageously be particularly stable in order to efficiently support the metal area (functional area) as a base platform and to limit movements of the elastomer in the x and y directions. For example, in one example, the entire electrode may have a thickness of around 50 µm. According to an exemplary embodiment, the electrode is designed as a metallized polyester film, in particular as a Steiner film (capacitor films from Steiner GmbH, D-57339 Erndtebrück, e.g. Steinerfilm T).

According to a further exemplary embodiment, the base material is a polymer film. In particular, the base surface is a polymer surface, and in particular the base material is a polymer film metallized on one side. This can have the advantage that a particularly stabilizing base material is provided.

In this exemplary embodiment, the application of the elastomer material does not take place directly on the metallic electrode, but on a polymer film metallized on one side. Such a film can, for example, be a polymer film (e.g. PET, PEN, PSU, PPSU) vapor-deposited with aluminum as metal. Such a (metallized) polymer film can be very stable and robust. This resilience enables the deposition of elastomer material with relatively high deformation forces (e.g. squeegee or screen printing). This is especially true at high viscosities and shear forces. Such stability can ultimately also lead to a higher mechanical load-bearing capacity of a finished dielectric device.

In a further preferred embodiment, the base material (e.g. a carrier film) is at least partially highly transparent (for electromagnetic radiation, in particular light). This has the advantage that an initiated crosslinking reaction (in particular by means of UV irradiation) can be carried out efficiently (in particular shortened crosslinking time) and in a targeted manner.

In one example, the base material has a metal layer and a polymer layer, the polymer material being (highly) transparent. The elastomer material is deposited on the polymer layer and then specifically (partially) cured by means of UV radiation. Because the polymer film is (at least partially) transparent, the UV radiation passes through the polymer film and is reflected, in particular totally reflected, by the metal layer underneath. As a result, the UV irradiation of the elastomer material can be particularly effective and the crosslinking time can be significantly shortened.

According to a further exemplary embodiment, the base (or the base material) has a rigidity of 1 GPa or more, in particular 5 GPa or more, further in particular 30 GPa or more. This particularly high rigidity can have the advantage that an undesirable non-linear Deformation of a finished dielectric device can be prevented during operation. This is because the dielectric is less pushed out to the sides between rigid base materials.

In one example, the base material can be a particularly rigid plastic film. In another example, the base material can also be a rigid metal foil, for example made of a stainless metal. The stiffness of the base material can help prevent the elastic dielectric from being squeezed out on the side, thus resulting in a highly non-linear deformation of the dielectric device. For example, the Steiner foil described above has a stiffness of about 5 GPa.

According to a further exemplary embodiment, the provision of the elastic dielectric comprises: setting the thickness of the elastomer layer. This in particular by partially removing non-hardened elastomer material and / or applying additional elastomer material. This has the advantage that the desired end properties (in particular the thickness) of the dielectric can be controlled flexibly and in a targeted manner.

As described above, an initially still liquid (uncured) dielectric is deposited on the base surface of the base, for which the relevant final thicknesses after solidification, e.g. below 200 (100) micrometers, are achieved in the dielectric. To set the desired thickness, either a corresponding additional application can be applied (in the event that the thickness is reduced after solidification (curing, crosslinking)), or a corresponding removal (removal) can be carried out. Such a thin application can be chosen, for example, if the elastomer material shows swelling during solidification.

A variety of methods (knife coating, spraying, rolling, pressing, etc.) can be used for thin application. Furthermore, partial crosslinking can be carried out in which initially only a lower area (closer to the base) of the elastomer material is solidified. As a result, a stable base area can be provided, on which the setting of the desired thickness can then be carried out. A further crosslinking step can then be carried out.

According to a further exemplary embodiment, the formation of the elastomer layer comprises: applying the elastomer material at least partially dissolved in a solvent or in dispersion with a solvent (in particular an aqueous and / or organic solvent). This has the advantage that uncured elastomer material can be applied using established processes.

Non-crosslinked elastomers can be soluble in high concentrations (e.g. up to 80%) in organic solvents (toluene, xylenes, cyclic ethers, halogenated hydrocarbons, etc.) and can be applied to the base material in this form. This, for example, by means of spraying, pouring, knife coating, brushing, or by means of a screen printing process.

In one embodiment, compounds are used as solvents which, due to their high boiling point and the special dissolving properties, can remain in the crosslinked elastomer and act as internal plasticizers. In the case of peroxide crosslinking, these can also be incorporated covalently.

In a further example, high-boiling solvents such as alkyl carbonates (e.g. ethylene glycol carbonate, propylene glycol carbonate, butyl glycol carbonate, neopentyl glycol carbonate, cyclohexanediol carbonate, or mixtures thereof) are used as solvents, which are retained during crosslinking and after crosslinking, preferably by means of peroxide and particularly preferably by means of UV Cross-linking, with which the elastomer forms a gel that exhibits special elastic properties.

According to a further exemplary embodiment, the viscosity of the solid (or essentially solid) dielectric is 10 ⁸ Ns / m ² or more. This has the advantage that the elastomer material with the desired properties is cured (or completely or largely crosslinked) and forms an advantageous elastic dielectric.

According to a further exemplary embodiment, the method further comprises: forming pores (in particular fluid-filled pores, further in particular gas bubbles) in the dielectric. In particular, the pores having an average diameter of 20 μm or less. Specifically, the pores make up 40 percent by volume or less of the dielectric. This can have the advantage that surprisingly advantageous and desired pores can be introduced in a simple manner during the production process.

The pores or gas bubbles produced in this way can create reserve spaces within the dielectric, into which the dielectric displaced during operation can penetrate and does not have to move laterally when the electrode spacing is reduced. Micro- to nano-scale pores (pores <20 micrometers in diameter) have proven to be particularly advantageous. A large number ( homogeneously) distributed pores, which do not make up more than 40% of the total volume of the dielectric.

In one embodiment, the non-hardened (liquid) dielectric is provided with an agent that allows micro- or nano-scale gas bubble expansion. This expansion process ideally takes place in the solidification phase, so that no or only minimal gas bubble coagulation occurs.

According to a further exemplary embodiment, the formation of pores comprises: subjecting the uncured elastomer layer to a fluid, in particular CO ₂ , at a predetermined pressure, and lowering the predetermined pressure during curing. This has the advantage that the surprisingly advantageous pores can be introduced efficiently.

An exemplary process for the preparation of the pores (gas bubbles) is to pressurize the liquid dielectric with CO ₂ under pressure and then reduce this pressure during solidification process, so that the hineindiffundierte CO ₂ expands in the gas phase and forms gas bubbles.

According to a further exemplary embodiment, a variation in the thickness of the dielectric has 20% or less, in particular 5% or less, based on the mean thickness. This particularly advantageous embodiment with an essentially constant thickness enables efficient operation of a dielectric device.

With a dielectric thickness of 20 micrometers, 20 percent already means a precision of 4 micrometers, which corresponds to a 25th of the diameter of a human hair. To achieve such a result, an extensive combination of competencies from different subject areas such as process engineering, chemistry, mechatronics and control technology may be necessary.

According to a further exemplary embodiment, the method further comprises: adding an additive to the elastomer material, the dielectric constant of the additive being different from the dielectric constant of the elastomer material. This can have the advantage that desired properties of the dielectric can be flexibly controlled.

Additives can include, for example, crosslinkers, peroxides, initiators or stabilizers, which take part in the curing process (e.g. through crosslinking reactions). In another example, the additive can also be a mineral fiber or a polymer fiber (e.g. glass fiber) which, when embedded in an elastomer material, increases the stability.

1. i) Carbon black, insbesondere nichtleitende Russ-Sorten, im mikro/nano-skalinen Bereich,
2. ii) Aerosil und andere nanoskaline Siliziumdioxid Pigmente, insbesondere zur Viskositätseinstellung bei einer optionalen Porenbildungsreaktion,
3. iii) Zinkoxid als Stabilisator und/oder Inhibitor,
4. iv) Antioxidantien wie Butylphenolverbindungen,
5. v) Acceleratoren wie Diphenylguanidin,
6. vi) Lichtschutzmittel wie HALS-Verbindungen, und
7. vii) weitere Rezepturbestandteile, wie Extender, Weichmacher etc.

In one embodiment, the additives can promote better aging resistance. In addition to the additives that have been tried and tested for rubber elastomers, the following additives have surprisingly proven particularly useful:

1. i) Carbon black, especially non-conductive soot types, in the micro / nano-scale range,
2. ii) Aerosil and other nanoscaline silicon dioxide pigments, especially for adjusting the viscosity in an optional pore formation reaction,
3. iii) zinc oxide as a stabilizer and / or inhibitor,
4. iv) antioxidants such as butylphenol compounds,
5. v) accelerators such as diphenylguanidine,
6. vi) light stabilizers such as HALS compounds, and
7. vii) other recipe ingredients, such as extenders, plasticizers, etc.

According to a further exemplary embodiment, the method is carried out in a reel-to-reel (roll-to-roll) process. This has the advantage that the method described can be carried out particularly efficiently and inexpensively.

In the context of this document, the term “reel-to-reel” can in particular denote a device and / or a method which is configured to carry out a reel-to-reel process. In a simplest embodiment, a reel-to-reel machine has two roles. A film-like material can be wound onto the first roll and connected to the second roll via a transport path. In the operating state, both rollers can rotate, preferably in the same direction. Here, the film-like material can be unwound from the first roll, transported over the transport path, and then wound up on the second roll. The transport route can offer the possibility of processing the film-like material and / or of applying further material. For example, the film-like material can be a printed circuit board material that is populated on the transport route. In another example, the film-like material can be a carrier film to which elastomeric material can be applied (eg to form an elastic dielectric). In a further example, the film-like material can be an elastomer film from which an elastic dielectric is produced. Furthermore, a reel-to-reel machine can be set up in such a way that the manufacturing process can be influenced in a targeted manner by setting process parameters. For example, in such a way that a targeted stretching and thus a preferred direction is provided in a dielectric. The direction of the transport path can be used as machine manufacturing direction (machine direction, MD). Furthermore, the width of the transport path (or width of the film-like material) oriented perpendicular to this can be referred to as the machine width direction (cross-direction, CD).

In one embodiment, the base material is provided in the form of a film on a reel and transported on to a further reel. Thus, the initial base material and the final or intermediate product are in the form of a film.

According to a further exemplary embodiment, the method further comprises: adding (in particular before curing) an adhesion-reducing and / or internal friction-reducing substance to the elastomer material. In particular, the substance has a fluoropolymer (e.g. PVDF, FEP, FCTFE, ETFE, etc., in particular PTFE). More particularly, the substance is present in the elastomer material in a concentration in the range 0.1 to 5%. In this way, an advantageous separating effect can be achieved.

In some embodiments, a disadvantage of the polymers according to the invention can be the good adhesion to metal surfaces, that is to say also to the shapes for structuring during the shaping and the simultaneous crosslinking. The more structured the surfaces (i.e. the higher the amplitude maxima and the finer the resolution), the more noticeable this effect in the interface area is (the minimum distance that two points must have in the horizontal surface of a surface, i.e. more than 90), can be referred to as resolution Percent of the measurements a planned height difference between the two points can be ascertained)) is therefore particularly relevant for the desired microscaline shape. The usual use of release agents by spray application of a conventional release agent (e.g. resin or silicone) between the mold and the elastomer fails in one example in addition to chemically / physically undesirable side effects, above all due to the necessary minimum layer thickness (1-5 micrometers) and the associated surface-leveling effect.

In one embodiment, a fluoropolymer (especially PTFE) is added as a micropowder, e.g. via a kneader into the still uncrosslinked elastomer compound, or by dispersing it in an elastomer solution before it is sprayed into the mold. As a result, the release properties can be massively improved.

A sufficient release effect can be achieved by adding 0.1 to 5%, based on the elastomer, with other fluoropolymers also showing comparable effects. The problem lies in the unavoidable inhomogeneity of the resulting elastomer, since these particles either have to be very finely structured (nanoscale would be optimal) or local changes in permittivity (PTFE has a value of 2.1) have to be accepted (ie the resulting micro-field distortions change the PD properties (with a massive influence on the long-term behavior) and the dielectric strength). Even an addition of 0.1-0.5% can bring about a pronounced release effect in the microstructuring of the crosslinking elastomer on metal surfaces as well as a surprising, changed relaxation behavior of the resulting film.

Without being tied to a specific theory, it is currently assumed that the internal friction losses during the deformation of the elastomer matrix (on a molecular scale) are significantly reduced.

According to a further exemplary embodiment, the hardening has a specifically initiated hardening step. This has at least one from the group consisting of: radiation crosslinking, in particular by means of UV radiation, electron crosslinking, in particular by means of an electron beam source, thermally initiated radical crosslinking, thermal sulfur crosslinking, peroxide-initiated radical crosslinking. This has the advantage that the targeted networking can be carried out using efficient and established processes.

In one embodiment, elastomers with UV-induced radical crosslinking capabilities are used. Due to the possibility of using initiators with different frequency selectivity, stiffeners at different depths or with different geometries are possible through simple exposure processes (pattern projection onto as yet non-crosslinked elastomer). In this way, different retardation properties can be implemented, which in turn can be used, for example, for a feedback control system.

According to a further exemplary embodiment, the curing includes: initiating a covalent bond between the elastomer material and a fluoropolymer, in particular PTFE, further initiated in particular by using free radicals.

It was surprisingly found that an elastomer that can be separated very easily can be produced which, as a result of the PTFE side chains which are covalently bound to the elastomer matrix, results in neither inhomogeneities nor a reduction in permittivity.

It is assumed that when PTFE fine powders are irradiated in an oxidizing (air) atmosphere with ionizing radiation at an intensity of over 100 kGy (preferably> 500 kGy) persistent PTFE peroxide radicals are created. It has been found that these (permanent) radicals are irreversibly incorporated into the molecular matrix directly with the polymers according to the invention, in the course of peroxide crosslinking.

According to a further exemplary embodiment, the method further comprises: structuring and / or perforating at least part of the surface of the not yet cured elastomer layer (in particular during curing) and / or the (essentially) solid dielectric. This in particular before applying the electrode material (the further electrode). This has the advantage that the adhesion of the further electrode can be improved and displacement space is provided for dielectric material. The structuring can be particularly successful in the not fully cured state.

So that the elastic dielectric finds a place for its displacement during the operation of the dielectric device, the surface of the elastic dielectric is structured in such a way that a non-planar surface is created, but rather a deliberately introduced waviness or roughness. With regard to the further (second electrode), for example, the following can be implemented: i) By using a significantly stiffer electrode in a sufficiently thick design (eg 5-50 μm), it remains essentially planar even when the dielectric device is in operation. The previously applied surface structuring then creates small to microscaline cavities between the dielectric and the counter electrode. The cavities formed in this way are now used as a displacement space for the elastomer displaced in the course of activation.
ii) The further electrode is not stiffened with respect to the structured surface in such a way that it remains flat (but at least partially follows the structuring of the dielectric surface). However, during operation, the elastic dielectric is deformed in such a way that, on average, there is a smaller electrode distance. This process is supported, for example, with an elastic electrode.

In one embodiment, the still liquid dielectric to be crosslinked is introduced between a carrier film (as a base) and a cover film (wherein the carrier film and cover film can also consist of the same material and / or the same structure, in particular the cover film can simultaneously form the (further) electrode and also again be the electrode of the next layer of a stacking system). This cover sheet can be perforated and also have a surface structure that deviates from a flat surface (both measures are suitable for forming displacement space). In particular, when using a transparent cover film, crosslinking can be carried out through this (e.g. by UV crosslinking). The introduction of the cover film can overcome technical obstacles when the NBR adheres to the embossing surface. This film can be very thin and thus also transfer the structuring from the outside (e.g. by rolling) into the uppermost elastomer material (NBR) zone. In particular, with very thin cover films (less than 20 micrometers, preferably less than 5 micrometers thick), good results were achieved. This process variant also allows the production of dielectrics with very few different properties in the MD and CD directions.

According to a further exemplary embodiment of the method, the structuring has at least one from the group which consists of: sandblasting, molding, pressing, stamping, using washable reagents. This can have the advantage that an advantageous structuring can be obtained cost-effectively using established methods.

According to a further exemplary embodiment, the structuring is produced by a soluble and / or washable structural material. In particular, this structural material is part of the base material. Additionally or alternatively, the structural material has at least one from the group consisting of: water-soluble salts, neutral salts, in particular NaCl, CaCO ₃ , Na ₂ SO ₄ .

In the still uncrosslinked state, a washable agent, which does not intervene reactively in the crosslinking process (e.g. water-soluble metal salts or water-soluble polymers, but also sugar, etc.) can be added to the dielectric on the surface, which washable agent can be washed out after crosslinking, and this leaves a structured surface.

According to a further exemplary embodiment, the electrode material is applied as a film (or foil) which has a thickness of 20 μm or less, in particular 5 μm or less. A particularly thin construction of a dielectric device can advantageously increase the sensitivity.

According to a further exemplary embodiment, the film (or the foil) is at least partially transparent. In particular, the crosslinking (in particular by means of UV) is carried out through the transparent film. The elastomer material is deposited on the polymer layer and then specifically (partially) cured by means of UV radiation. Because the film is (at least partially) transparent, the UV radiation passes through the film and is reflected, in particular totally reflected, by the underlying (electrode) metal layer. As a result, the UV irradiation of the elastomer material can be particularly effective and the crosslinking time can be significantly shortened.

According to a further exemplary embodiment of the device, at least part of a surface of the dielectric is structured and / or perforated. In particular, electrode material is arranged in the structures and / or perforations. See description of the structuring above.

According to a further exemplary embodiment of the device, at least part of a surface of at least one of the two electrodes is structured and / or perforated. In particular, dielectric material is arranged in the structures and / or perforations.

According to a further exemplary embodiment, the first electrode is different from the second electrode. This in particular with regard to the mechanical properties (in particular the elasticity), further in particular with regard to the thickness and / or the material composition. As a result, various advantageous properties can be achieved in a flexible manner.

• 1a, 1b, und 1c zeigen jeweils eine dielektrische Vorrichtung gemäß einem Ausführungsbeispiel der Erfindung.
• 1d zeigt eine dielektrische Vorrichtung als Stapelaktor/sensor gemäß einem Ausführungsbeispiel der Erfindung.
• 2a bis 2e zeigen ein Verfahren zum Herstellen eines elastischen Dielektrikums für eine dielektrische Vorrichtung gemäß einem Ausführungsbeispiel der Erfindung.

In the following, exemplary embodiments of the present invention are described in detail with reference to the following figures.

• 1a , 1b , and 1c each show a dielectric device according to an embodiment of the invention.
• 1d shows a dielectric device as a stack actuator / sensor according to an embodiment of the invention.
• 2a to 2e show a method for producing an elastic dielectric for a dielectric device according to an embodiment of the invention.

1. i) Aussergewöhnliche Reinheit der beteiligten Komponenten. Bereits bei minimalen Fremdmaterialanteilen könnte eine Feldstörung produziert werden, welche dann eine reduzierte Hochspannungsfestigkeit in einer dielektrischen Vorrichtung bewirkt.
2. ii) Besondere Homogenität der noch flüssigen Materialien. Mangelhafte Homogenität in den Ausgangsmaterialien kann zu einer Verschiebung der relativen Dielektrizitätskonstante im Inneren des Materials führen, was wiederum eine Feldverzerrung bewirken kann. Entsprechende Feldverzerrungen können ebenfalls zu einer tieferen Hochspannungsfestigkeit oder einer damit verbundenen reduzierten Lebenserwartung des entsprechenden Bauteils führen.
3. iii) Vermeidung von Lufteinschlüssen. Diese können ebenfalls eine Feldverzerrung mit den oben genannten Folgen bei einer für dielektrische Vorrichtungen üblichen hohen Spannung auslösen.
4. iv) Dickenvariationen minimieren. Dadurch können weniger relevante Feldverschiebungen auftreten. Es wurde gefunden, dass ab einer Dickengenauigkeit von 20%, und genauer, über die gesamte Fläche ein erwünschtes Ergebnis erzielt werden konnte. Bei Dickengenauigkeiten von unter 5% wurden besonders erwünschte Ergebnisse erreicht. Bei Dicken von 20 Mikrometern bedeuten 20 Prozent bereits eine Präzision von 4 Mikrometern, was einem 25-igstel des Durchmessers eines menschlichen Haares entspricht. Solche Produktionsergebnisse bedürfen der Kombination der Kompetenzen von verschiedenen Fachgebieten wie Verfahrenstechnik, Chemie, Mechatronik, und Regeltechnik.
5. v) Vermeidung einer anisotropen Elastomerausgestaltung. Eine solche kann durch Laminierprozesse oder anderen Verfahren entstehen, bei welchen eine dünne Folie abgerollt wird und so aufgrund der Abzugsspannung eine Anisotropie bezüglich der Elastizitätseigenschaften geschaffen ist. Dies kann eine Nichtlinearität in der Bewegungsfreiheit in z-Richtung bewirken.

According to an exemplary embodiment, the method described can enable the following advantages:

1. i) Exceptional purity of the components involved. Even with a minimal amount of foreign material, a field disturbance could be produced, which then causes a reduced high-voltage strength in a dielectric device.
2. ii) Particular homogeneity of the still liquid materials. Poor homogeneity in the starting materials can lead to a shift in the relative dielectric constant inside the material, which in turn can cause a field distortion. Corresponding field distortions can also lead to a lower high voltage strength or a related reduced life expectancy of the corresponding component.
3. iii) Avoidance of air pockets. These can also cause a field distortion with the consequences mentioned above at a high voltage customary for dielectric devices.
4. iv) minimize thickness variations. This means that less relevant field shifts can occur. It was found that from a thickness accuracy of 20%, and more precisely, a desired result could be achieved over the entire surface. Particularly desirable results were achieved with thickness accuracies of less than 5%. At a thickness of 20 micrometers, 20 percent already means a precision of 4 micrometers, which corresponds to a 25th of the diameter of a human hair. Such production results require the combination of competencies from various specialist areas such as process engineering, chemistry, mechatronics and control technology.
5. v) Avoidance of an anisotropic elastomer design. This can arise through lamination processes or other processes in which a thin film is unrolled and an anisotropy with regard to the elasticity properties is created due to the pull-off tension. This can cause a non-linearity in the freedom of movement in the z-direction.

Identical or similar components in different figures are provided with the same reference numbers.

1a Figure 3 shows a dielectric device 100 which can be used as a dielectric actuator (DEA), a dielectric sensor (DES) or a mixed form (DEAS). The device 100 has a first electrode 110 and a second electrode 120 on, with the second electrode 120 opposite the first electrode 110 is arranged. Furthermore, the device 100 an elastic dielectric 130 on, which is between the first electrode 110 and the second electrode 120 is arranged. The electrodes 110 , 120 each have a contact area 114 on, which consists of electrically conductive material and over which the electrodes 110 , 120 can be contacted, or over which a voltage U can be created. The second electrode 120 represents the counter electrode to the first electrode 110 each of the two electrodes 110 , 120 is electrically contacted separately, so that an electric field by means of the electrodes 110 , 120 can be generated. In the one shown Example no voltage is applied (0 volts), so the dielectric device 100 is not in an operating mode.

Each of the two electrodes 110 , 120 has a functional area 112 on, which has an electrically conductive metal. The functional area 112 is plate-shaped and thus extends along two main directions of extent x, y, the functional area 112 an area level E. spans. In the example shown, the functional area makes 112 the whole electrode plate 110 out. In other exemplary embodiments, the electrode 110 an (insulating) carrier material on which the functional area is then placed 112 is arranged (e.g. vapor-deposited).

1b Figure 10 shows the dielectric device 100 according to 1a , with the electrodes 110 , 120 electrically at the respective contact areas 114 have been contacted. In the example shown there is a voltage of 1 kV on the electrodes 110 , 120 applied so that the dielectric device 100 is in an operating mode. The first electrode 110 now forms a positive pole and the second electrode 120 (Counter electrode) forms the negative pole. This electrical contact leads to the positively charged first electrode 110 and the negatively charged second electrode 120 attract each other and move spatially towards each other. If the dielectric 130 , which between the first electrode 110 and second electrode 120 is arranged as an elastic dielectric (for example as an elastomer), it is due to its incompressibility to the sides of the dielectric device 100 partially pressed out.

1c shows the principle of operation of the dielectric device 100 (as for the 1a and 1b described above) as a dielectric actuator or sensor. Becomes a tension U to the electrodes 110 , 120 applied, the electrode plates move towards each other. This in turn creates pressure P. on the dielectric 130 which is between the electrodes 110 , 120 is arranged. If the dielectric 130 is designed as an elastomer, it is essentially incompressible and is forced to expand by the pressure from above (z +) and from below (z-). The surface area (see the movement arrows pointing outwards) takes place along the two main directions of extension x, y of the electrodes 110 , 120 instead of.

1d Figure 11 shows a plurality of dielectric devices 100 according to the 1a to 1c which are arranged in the form of a stack actuator (or stack sensor) or a stack system. Here, the individual dielectric devices 100 in height direction (z) one above the other to form a dielectric device 100 stacked from multiple units. Under the first electrode 110 and the second electrode 120 (between which the first dielectric 130 is arranged) is now a third electrode 121 arranged which the second electrode 120 is arranged opposite. A second elastic dielectric is correspondingly 131 between the third electrode 121 and the second electrode 120 arranged. This arrangement can be continued by means of a fourth electrode and a third dielectric, etc. The first electrode 110 and the third electrode 121 are at their contact areas 114 (eg via a bonding wire) connected in an electrically conductive manner. The second electrode 120 (and then the fourth electrode, etc.) are the counter electrodes in this case 160 again, the counter electrodes 160 with one another by means of bonding wires 118 at their contact areas 114 are connected to one another in an electrically conductive manner. In further embodiments, several such stacks can also be arranged next to one another and used jointly.

The 2a to 2e show an exemplary embodiment of the method for producing the elastic dielectric 130 for the dielectric device described above 100 . This method can be carried out particularly advantageously, for example, by means of a reel-to-reel (roll-to-roll) machine.

2a : One Base 210 , which is a base material with a base surface 212 is provided. The base material 210 has a high rigidity of about 5 GPa or more (particularly 30 GPa or more). The base material 210 is part of an electrode 110 and the base surface 212 is an electrically conductive (metallic) functional area 112 the electrode 110 . The electrode 110 is particularly thin (less than 50 µm thick). The base material 210 is in a preferred example on the base surface 212 partially structured and / or perforated, or provides a plurality of surface structures.

2 B : An elastomer layer 230 made of uncured (essentially uncrosslinked) elastomer material is applied to the base surface 212 educated. The elastomer material has an elastic copolymer, which in turn has NBR or a derivative thereof. The elastomer material is dissolved in a solvent or suspended in a suspending medium on the base surface 212 applied. In one embodiment, uncured elastomer material can be used in the surface structures of the base material 210 penetration.

2c : The elastomer layer 230 is cured, the curing being a crosslinking reaction and / or film formation by drying comprises from a solution or dispersion. The curing can be carried out by a specifically initiated curing step. Such a specifically initiated curing step comprises a targeted crosslinking, for example radiation-initiated (UV radiation, electron beam source), thermally initiated (sulfur), or peroxide initiated.

The fat ( d ) the elastomer layer 230 is set in a targeted manner, so that the elastic dielectric to be produced 130 has a thickness of less than 100 µm, in particular less than 50 µm. Such a small thickness for an NBR copolymer can be achieved, among other things, by selectively ablating or removing uncured elastomer material. Furthermore, the desired thickness can also be achieved by selectively adding elastomeric material. A lower area of the elastomer material, which is more hardened than an upper area of the elastomer material, can provide the necessary stability.

The second region 230b of the elastomer layer 230 is now cured in such a way that the elastomer layer 230 a substantially solid dielectric 130 forms. This solid dielectric 130 has a viscosity of 10 ⁸ Ns / m ² or more. This process can additionally have: Formation of special, particularly small pores (mean diameter of 20 μm or less) in the dielectric 130 .

The elastic dielectric provided by the process described above 130 has particularly advantageous properties. A variation in thickness d of the elastic dielectric obtained 130 is 5% or less based on the mean thickness of the elastic dielectric 130 . The elastic dielectric 130 has a thickness of less than 100 µm.

2d : A surface of the elastic dielectric 130 is structured or perforated (eg by means of a structuring agent) to create surface structures 150 provide.

2e : On the (on the electrode base material 110 ) provided elastic dielectric 130 an electrode material is applied to a second electrode 120 provide which of the first electrode 110 opposite, the elastic dielectric 130 then between the first electrode 110 and the second electrode 120 is arranged. In this way, the dielectric device 100 , in particular a dielectric actuator and / or a dielectric sensor.

When the electrode material is applied, it can at least partially be inserted into the surface structures 150 of the dielectric 130 penetration. After the elastomer material has cured, the electrode can 120 especially good about the essentially solid dielectric 130 be liable.

In addition, it should be pointed out that “having” does not exclude any other elements or steps and “one” or “one” does not exclude a plurality. Furthermore, it should be pointed out that features or steps that have been described with reference to one of the above exemplary embodiments can also be used in combination with other features or steps of other exemplary embodiments described above. Reference signs in the claims are not to be regarded as a restriction.

List of reference symbols

100

Dielectric device

110

First electrode, metal foil

112

Functional (electrically conductive) area

114

Contact area

120

Second electrode

121

Third electrode

130

(First) dielectric

131

Second dielectric

150

structuring

160

Counter electrode

210

Base (material)

212

Base surface

230

Elastomer layer, not hardened

d

thickness

E.

Area level

P

print

U

tension

X, Y

Main directions of extent

Z

Height direction

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Non-patent literature cited

• DIN 53523 / ISO 289 [0024]

Claims (29)

A method for producing an elastic dielectric (130) for a dielectric device (100), in particular a dielectric actuator and / or a dielectric sensor, the method comprising: Providing a base (210) having a base surface (212); Forming an elastomer layer (230) from uncured elastomer material on the base surface (212), wherein the elastomer material comprises a copolymer, wherein the copolymer comprises nitrile-butadiene rubber, NBR, or a derivative thereof; and at least partial curing, in particular crosslinking, of the elastomer layer (230) to provide the elastic dielectric (130), the elastic dielectric (130) having a thickness (d) of 100 μm or less. The procedure according to Claim 1 wherein the ratio of the nitrile monomer unit, or a derivative thereof, and the butadiene monomer unit, or a derivative thereof, is in the range 1: 1 to 1: 5. The procedure according to Claim 1 , wherein the copolymer comprises: a first monomer unit represented by the following formula (F1): - [CH ₂ -C (R ₁ ) H] - (F1) where R1 is selected from: CN, CO (OH), and CO (NH ₂ ); and a second monomer unit represented by the following formula (F2): - [C (R ₂ ) H- (XY) -CH ₂ ] - (F2) wherein: R2 is selected from: H, and CH ₃ ; X is selected from: -CH =, -CH ₂ -, -C (CH ₃ ) =, and -C (CH ₃ ) H-; and Y is selected from: -CH =, and -CH ₂ -. The procedure according to Claim 3 wherein the ratio of the first monomer unit to the second monomer unit is in the range 1: 1 to 4, in particular 1: 2 or 3; or wherein the ratio of the first monomer unit to the second monomer unit is in the range 2: 2 to 10, in particular 2: 4 to 8. The procedure according to Claim 3 or 4th wherein when X and Y are each -CH = and / or -C (CH ₃ ) =, 50% or more of the double bonds between X and Y are in the cis configuration in the elastic copolymer. The method of any one of the preceding claims, further comprising: at least partial production of structuring (150) on the surface of the elastomer layer (230), in particular during the at least partial curing, further in particular by means of a structuring agent. The procedure according to Claim 6 , the majority of the structures (150) extending by 100 μm or less, in particular 10 μm or less, in a height direction (z) which is oriented perpendicular to the main directions of extension (x, y) of the elastic dielectric (130). The method according to any one of the preceding claims, wherein the elastic dielectric (130) has a thickness (d) of 70 µm or less, in particular 20 µm or less, further in particular 5 µm or less. The method according to any one of the preceding claims, wherein the base (210) is a base material and has a thickness of 50 µm or less, in particular where the base material (210) is part of an electrode (110), further in particular where the base surface (212 ) is an electrically conductive, in particular metallic, functional area (112) of the electrode (110). The procedure according to Claim 9 wherein the electrode (110) is a multilayer electrode which has a carrier material, in particular a polymer, the functional region (112) being applied, in particular vapor-deposited, to the carrier material; or wherein the base material (210) is a polymer film, in particular wherein the base surface (212) is a polymer surface, further in particular wherein the base material (210) is a polymer film metallized on one side. The method according to any one of the preceding claims, wherein the base material (210) has a stiffness of 1 GPa or more, in particular 5 GPa or more, further in particular 30 GPa or more; and or wherein the base material (210) is at least partially structured and / or perforated. The method of any one of the preceding claims, wherein providing the resilient dielectric (130) comprises: Adjustment of the thickness (d) of the elastomer layer (230), in particular partial removal of uncured elastomer material and / or application of additional elastomer material. The method of any one of the preceding claims, wherein forming the elastomeric layer (230) comprises: Application of the elastomer material at least partially dissolved in a solvent or in dispersion with a solvent, in particular an aqueous solvent. The method of any one of the preceding claims, further comprising: Forming pores in the dielectric (130), in particular wherein the pores have an average diameter of 20 μm or less, and / or wherein the pores make up 40 percent by volume or less of the dielectric (130). The method according to any one of the preceding claims, wherein a variation in the thickness (d) of the dielectric (130) is 20% or less, in particular 5% or less, based on the mean thickness of the dielectric (130). The method of any one of the preceding claims, further comprising: Adding an additive to the elastomeric material, the dielectric constant of the additive being different from the dielectric constant of the elastomeric material. The method according to any one of the preceding claims, wherein the method is carried out at least in part by means of a reel-to-reel machine. The method of any one of the preceding claims, further comprising: Adding, in particular before curing, an adhesion-reducing and / or internal friction-reducing substance to the elastomer material, in particular wherein the substance comprises a fluoropolymer, in particular PTFE, and / or in a concentration in the range 0.1 to 5% in the Elastomer material is present. The method according to any one of the preceding claims, wherein the curing has a specifically initiated curing step, in particular at least one from the group consisting of: Radiation crosslinking, in particular by means of UV radiation; Electron crosslinking, in particular by means of an electron beam source; thermally initiated radical crosslinking; thermal sulfur crosslinking; Peroxide-initiated radical crosslinking. The method of any one of the preceding claims, wherein curing comprises: Initiating a covalent bond between the elastomer material and a fluoropolymer, particularly PTFE, further particularly initiated by using free radicals. A method for producing a dielectric device (100), in particular a dielectric actuator and / or a dielectric sensor, the method comprising: providing an elastic dielectric (130) according to any one of the Claims 1 to 20th ; Application of electrode material, in particular to the not yet hardened elastomer material; Forming an electrode (120) from the electrode material, in particular such that the electrode (120) adheres to the dielectric (130). The procedure according to Claim 21 , further comprising: structuring and / or perforating at least part of the surface of the not yet cured elastomer layer (230), in particular during curing, and / or the solid dielectric (130), in particular before the electrode material is applied. The procedure according to Claim 22 , the structuring being achieved by a soluble and / or washable structural material, in particular where this structural material is part of the base material, and / or where the structural material has at least one from the group consisting of: water-soluble salts, neutral salts, in particular NaCl , CaCO ₃ , Na ₂ SO ₄ . The method according to any of the Claims 21 to 23 wherein the electrode material is applied as a film which has a thickness of 20 μm or less, in particular 5 μm or less. The procedure according to Claim 24 wherein the film is at least partially transparent, in particular wherein the crosslinking, in particular by means of UV radiation, is carried out through the transparent film. A dielectric device (100), in particular a dielectric actuator and / or a dielectric sensor, comprising: a first electrode (110); a second electrode (120) which is arranged opposite the first electrode (110); and an elastic dielectric (130) which is arranged between the first electrode (110) and the second electrode (120), in particular wherein the dielectric (130) is produced according to any of the Claims 1 to 20th wherein the elastic dielectric (130) comprises a copolymer, the copolymer comprising nitrile-butadiene rubber, NBR, or a derivative thereof, and wherein the elastic dielectric (130) has a thickness (d) of 100 μm or less. The dielectric device (100) according to Claim 26 wherein at least part of a surface of the dielectric (130) is structured and / or perforated, in particular with electrode material being arranged in the structures (150) and / or perforations. The dielectric device (100) according to Claim 26 or 27 , wherein the first electrode (110) is different from the second electrode (120), in particular with regard to the mechanical properties, further in particular with regard to the thickness and / or the material composition. Use of a copolymer in an elastic dielectric (130) of a dielectric device (100), in particular a dielectric device (100) which is designed as a stack system, the copolymer having: a first monomer unit, which is represented by the following formula (F1): - [CH ₂ -C (R ₁ ) H] - (F1) where R1 is selected from: CN, CO (OH), and CO (NH ₂ ); and a second monomer unit represented by the following formula (F2): - [C (R ₂ ) H- (XY) -CH ₂ ] - (F2) wherein: R ₂ is selected from: H, and CH ₃ ; X is selected from: -CH =, -CH ₂ -, -C (CH ₃ ) =, and -C (CH ₃ ) H-; and Y is selected from: -CH =, and -CH ₂ -.

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