EP2376279A2 - Composite à deux couches ou multicouche à ferroélectret et procédé de fabrication dudit composite - Google Patents

Composite à deux couches ou multicouche à ferroélectret et procédé de fabrication dudit composite

Info

Publication number
EP2376279A2
EP2376279A2 EP09764187A EP09764187A EP2376279A2 EP 2376279 A2 EP2376279 A2 EP 2376279A2 EP 09764187 A EP09764187 A EP 09764187A EP 09764187 A EP09764187 A EP 09764187A EP 2376279 A2 EP2376279 A2 EP 2376279A2
Authority
EP
European Patent Office
Prior art keywords
polymer film
cavities
polymer
composite
films
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP09764187A
Other languages
German (de)
English (en)
Inventor
Werner Jenninger
Joachim Wagner
Günther WALZE
Dirk Schapeler
Heinz Pudleiner
Gunther Stollwerck
Reimund Gerhard
Werner Wirges
Ruy Alberto Altafim
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bayer Intellectual Property GmbH
Original Assignee
Bayer MaterialScience AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bayer MaterialScience AG filed Critical Bayer MaterialScience AG
Priority to EP09764187A priority Critical patent/EP2376279A2/fr
Publication of EP2376279A2 publication Critical patent/EP2376279A2/fr
Pending legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
    • B32B3/30—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by a layer formed with recesses or projections, e.g. hollows, grooves, protuberances, ribs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
    • B32B27/281—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42 comprising polyimides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
    • B32B27/285—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42 comprising polyethers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/306—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl acetate or vinyl alcohol (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B32B27/322—Layered products comprising a layer of synthetic resin comprising polyolefins comprising halogenated polyolefins, e.g. PTFE
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • B32B27/325—Layered products comprising a layer of synthetic resin comprising polyolefins comprising polycycloolefins
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • B32B27/365—Layered products comprising a layer of synthetic resin comprising polyesters comprising polycarbonates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B38/00—Ancillary operations in connection with laminating processes
    • B32B38/06—Embossing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • H04R17/02—Microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R23/00—Transducers other than those covered by groups H04R9/00 - H04R21/00
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/09—Forming piezoelectric or electrostrictive materials
    • H10N30/098—Forming organic materials
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/85—Piezoelectric or electrostrictive active materials
    • H10N30/857—Macromolecular compositions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2270/00—Resin or rubber layer containing a blend of at least two different polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/30—Properties of the layers or laminate having particular thermal properties
    • B32B2307/302—Conductive
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2419/00—Buildings or parts thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2439/00—Containers; Receptacles
    • B32B2439/70—Food packaging
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2605/00—Vehicles
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/50—Piezoelectric or electrostrictive devices having a stacked or multilayer structure
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T156/00—Adhesive bonding and miscellaneous chemical manufacture
    • Y10T156/10—Methods of surface bonding and/or assembly therefor
    • Y10T156/1002—Methods of surface bonding and/or assembly therefor with permanent bending or reshaping or surface deformation of self sustaining lamina
    • Y10T156/1039—Surface deformation only of sandwich or lamina [e.g., embossed panels]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T156/00—Adhesive bonding and miscellaneous chemical manufacture
    • Y10T156/14—Surface bonding means and/or assembly means with shaping, scarifying, or cleaning joining surface only

Definitions

  • the present invention relates to processes for the production of two- and multi-layer ferroelectrets with defined cavities and ferroelectret multi-layer composites prepared by these processes.
  • polymers and polymer composites are used in a variety of commercial applications. They are used for example as packaging material for food or other goods, as construction or insulation materials, for example in construction or in vehicle construction. Functional polymers are increasingly gaining in importance as active components in sensor or actuator applications.
  • An important application concept relates to the use of the polymers as electromechanical or piezoelectric transducers. Piezoelectric materials are capable of linearly converting a mechanical pressure into an electrical voltage signal. Conversely, an electric field applied to the piezoelectric material can be transformed into a change in transducer geometry. Piezoelectric materials are already being integrated as active components in a variety of applications.
  • WO 2006/053528 Al for example, an electroacoustic transducer based on a piezoelectric element of polymer films is described.
  • ferroelectrets are made of polymeric materials with a cavity structure that can store electrical charges over long periods of time.
  • the previously known ferroelectrets have a cellular cavity structure and are formed either as foamed polymer films or as multilayer systems of polymer films or polymer fabrics. If electric charges are distributed on the different surfaces of the cavities according to their polarity, each charged cavity represents an electric dipole. If the cavities are now deformed, this causes a change in the dipole size and leads to a current flow between external electrodes.
  • the ferroelectrets can exhibit a piezoelectric activity comparable to that of other piezoelectrics.
  • No. 4,654,546 describes a process for producing polypropylene foam films as a precursor to a ferroelectret film.
  • the polymer films are mixed with filler particles.
  • the filler used is, for example, titanium dioxide.
  • the polypropylene films are biaxially stretched after extrusion so that small voids are formed in the film around the filler particles. This method has since been applied to other polymers. For example, M. Wegener, M. Paajanen, O. Voronina, R. Schulze, W. Wirges, and R.
  • Another method for producing foamed ferroelectret polymer films is the direct physical foaming of a homogenous film with supercritical fluids, for example with carbon dioxide.
  • Advanced Functional Materials 17, 324-329 (2007), Werner Weges, Michael Wegener, Olena Voronina, Larissa Zirkel, and Reimund Gerhard-Multhaupt Optimized preparation of elastically soft, highly piezoelectric, cellular ferroelectrets from nonvoided poly (ethylene terephthalate) films "and in Applied Physics Letters 90, 192908 (2007), P. Fang, M. Wegener, W. Wirges, and R. Gerhard L.
  • T129 pp 274-277, 2007 describes the structuring of the polymer layers by pressing a metal lattice onto a polymer layer stack comprising at least three FEP and PTFE layers superimposed in alternating succession.
  • a polymer layer stack comprising at least three FEP and PTFE layers superimposed in alternating succession.
  • the polymer layers are interconnected according to the grid structure such that dome-shaped or bubble-shaped cavities with a rectangular base area form between the bars.
  • this method leads to ferroelectrets of different quality, since the formation of uniform cavities is difficult to control, especially with increasing number of layers.
  • Another method of producing bubble-shaped cavities using a grid is by RAC Altafim, HC Basso, RAP Altafim, L. Lima, CV De Aquino, L. Gonalves Neto and R. Gerhard-Multhaupt, in "Piezoelectrets from thermo-formed bubble structures of fluoropolymer-electret films, IEEE Transactions on Dielectrics and Electrical Insulation, Vol. 13, No.5, pp. 979-985, 2006.
  • two superimposed Teflon-FEP films between a metal grid and an upper cylindrical metal part are arranged. This structure is pressed with the metal grid on a lower cylindrical metal part, which has openings for applying a vacuum.
  • the FEP films are heated by the upper metal part and by a vacuum applied to the lower metal part the lower film is pulled into the openings of the grid and corresponding cavities are formed.
  • the described methods using a lattice to form voids in the polymer multilayer composites are expensive and difficult to scale-up.
  • Ferroelectrets continue to be of increasing interest to commercial applications such as sensor, actuator and generator systems. For economy, an applicability of a manufacturing process on an industrial scale is essential.
  • the invention is therefore based on the object to provide alternative ferroelectret multi-layer composites and alternative methods for the production of Fe ⁇ Oelektret multi-layer composites with which defined Ferroelektret cavity structures can be produced and which can be carried out easily and inexpensively on a large scale and industrial scale.
  • this object is achieved by the process for producing ferroelectret multilayer composites according to claim 1 and a ferroelectret multilayer composite produced by this process according to claim 12 or 13.
  • a method for producing a ferroelectret two- or multi-layer composite with defined cavities comprising the following steps: a) structuring at least one first surface of at least one first polymer film to form a height profile; b) applying at least one second polymer film to the structured surface of the first polymer film formed in step a), c) bonding the polymer films to form a polymer film composite to form closed and / or open cavities and d) electrically charging the inner surfaces of step c) formed
  • the two-layer and multi-layer composites produced according to the invention have stacked polymer films and at least voids formed between in each case two polymer films.
  • the polymer films are connected to each other between the cavities.
  • the shape and dimensioning of the cavities can be produced according to the invention very precisely predetermined and defined.
  • the structuring in step a) and the formation of the height profile on at least one surface of at least the first polymer film in the process according to the invention are decisive for the formation of the defined cavities in the resulting polymer film composite.
  • the method according to the invention makes it possible to produce in a simple manner ferroelectret multilayer systems with defined cavity structures. With the erf ⁇ ndungswashen approach, it is also possible to variably set the resonant frequency and piezoactivity, and in particular the piezoelectric constant d33, to the respective application.
  • high and uniform piezoelectric coefficients can also be achieved for larger areas with the ferroelectret multi-layer composite systems produced according to the invention. This basically opens up numerous applications for these ferroelectret multilayer composites.
  • An additional advantage is that the processes proposed according to the invention are largely independent of material and can be automated.
  • the polymer films used can be made of any plastic which permits the formation of a height profile, the connection between the polymer films and the formation of voids between the films.
  • the polymer films used may consist of identical or different polymer materials, for example from the group of polycarbonates, perfluorinated or partially fluorinated polymers and copolymers such as PTFE, fluorinated ethylene propylene (FEP), perfluoroalkoxyethylenes (PFA), polyesters such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN), Cyclo-olefin polymers, cyclo-olefin copolymers, polyimides, in particular polyetherimide, polyethers, polymethyl methacrylate.
  • PTFE perfluorinated or partially fluorinated polymers and copolymers
  • FEP fluorinated ethylene propylene
  • PFA perfluoroalkoxyethylenes
  • PET polyethylene terephthalate
  • PEN polyethylene n
  • the polymer films may preferably have a thickness of> 10 ⁇ m to ⁇ 500 ⁇ m, more preferably of> 15 ⁇ m to ⁇ 300 ⁇ m.
  • the thickness of the various polymer films in a ferroelectret multi-layer composite according to the invention can be chosen to be the same or different.
  • a particularly suitable thickness of the polymer films can advantageously be selected in each case depending on the polymer material and with regard to the desired application. It is fundamentally important that the cavities formed in step c) of the method do not collapse. Thus, stiffer materials can be made thinner than comparatively more elastic polymer materials.
  • the polymer films can be advantageously configured as film sheets or, in particular with regard to large-scale production, also as film webs which can be arranged one above the other in step b) and joined together to form the cavities in step c).
  • the foil sheets may have, for example, a rectangular, a regular or irregular polygonal shape or a round, for example circular, elliptical or oval base surface, wherein the films arranged one above the other expediently have the same base surface.
  • the base can also be attached to a special
  • step b) of the method according to the invention in other words, a layered polymer film stack is provided.
  • the overall height of the polymer film composite and the number of cavities and the number of cavities can be determined via the selected total number of polymer films and the selected sequence of structured and unstructured polymer films.
  • a layer of cavities the voids between two identical polymer films are understood.
  • two, three or more polymer films with intervening cavities can be arranged one above the other and joined together.
  • all the polymer films used can also have a height profile, that is to say structuring.
  • the outwardly directed surfaces are compact or not structured. This may optionally facilitate the application of electrodes on these outer surfaces of the polymer film composite.
  • a non-structured or unilaterally structured polymer film can additionally be arranged in the top and bottom of the polymer film stack as a cover film. These cover films form the outer surface of the subsequently formed polymer film composite as a cover with its non-structured surface.
  • the variants according to the invention in which three or more polymer films and correspondingly also several layers of cavities in the ferroelectret multilayer composite are made softer compared to those with only two polymer films and the additional cavities present the sensitivity of the composite and thus the piezoelectric constant d33 increase.
  • step d) can be used for the electrical charging and polarity of the inner surfaces of the cavities advantageously on known and established methods.
  • a polarity of the opposite sides of the cavities can be realized for example by a corona discharge or by plasma processes.
  • a corona treatment is advantageously also suitable for large-scale use.
  • the structuring of the at least one surface of the first polymer film in step a) can take place by means of an embossing process.
  • the embossing process can be carried out using a structured roller or by means of a stamping die. Both with the use of a structured roller, as well as with a structured embossing stamp each formed on the surface of the embossing tool structure can be transferred to form a height profile on a polymer film. It is possible to apply positive or negative forms on the surface of the embossing tool, that is to say the roller or the embossing punch.
  • the structuring can be carried out directly after the extrusion of the films or as a single process, for example in a hot press. It is also included according to the invention that the respective polymer films can be processed from both surface sides with an embossing tool. For example, a polymer film can be embossed from its top and bottom sides, each with a structured roller, and thus structured.
  • a polymer film can be heated to a temperature below its softening temperature (glass transition temperature) and then suddenly deformed by application of compressed air of> 20 to ⁇ 300 bar.
  • polycarbonate films can be heated (for example Macrofol Bayer MaterialScience AG) just below the glass transition temperature to 130-140 0 C. Thereafter, the films can be subjected to an air pressure of 250 bar and pressed onto a mold and can adapt to the tool contour and be permanently deformed.
  • the polymer films used for example, a thickness of> 10 microns to ⁇ 500 microns and the depressions and / or elevations formed have a height of> 10 microns to ⁇ 500 microns, and a width of> 10 microns to ⁇ 5000 microns.
  • the cavities have a width of> 100 microns to ⁇ 2000 microns.
  • An analogous method is already established, in particular in the repetitive deformation of printed plastic films and described for example in the published patent application DE 39 05 177 A1.
  • a polymer film can be positioned on a pallet system, heated if necessary and deformed in a corresponding mold over a pre-tempered contour insert by applying pressure.
  • This high pressure forming process is also called High Pressure Forming (HPF); or HPF process.
  • HPF High Pressure Forming
  • an apparatus of analogous construction to that described in DE 39 05 177 A1 can also be used for structuring the polymer films in step a).
  • All the structuring variants mentioned have the advantage that position-accurate transmission of the respective desired profile to the polymer films is made possible.
  • Both shape and dimensioning of the cavities then formed in the next step b) can advantageously be selected almost arbitrarily with the methods mentioned above and can be adapted to the desired mechanical and electrical requirements of the respective application depending on the film materials and their properties and the respective film thickness ,
  • the combination of the film properties and the shape and dimensioning of the formed cavities is chosen so that the distance to be held foil sections can touch in any case of use.
  • the said structuring methods also have the advantage that they can be automated and, if appropriate, can be carried out as a continuous process.
  • the structuring of the at least one surface of the first polymer film in step a) can also be effected by slot extrusion of the polymer film with a correspondingly shaped nozzle.
  • slot extrusion is advantageously an already established process, which can also be carried out continuously and automatically beyond.
  • the cavities may, for example, have a height of> 10 ⁇ m to ⁇ 500 ⁇ m at a polymer film thickness of> 10 ⁇ m to ⁇ 500 ⁇ m.
  • height is meant in particular the height of the cavities in cross section.
  • the cavities can have a height of> 10 ⁇ m to ⁇ 250 ⁇ m.
  • the cavities can be formed by the method according to the invention in many different forms.
  • the shape of the cavities is therefore not limited to a cylindrical, tubular or channel-like shape having a circular or rectangular cross-sectional area perpendicular to the layer course of the polymer films.
  • the inventive method offers the possibility to combine formed in different shapes cavities. In this way, on the one hand advantageously, the total void volume of the resulting cavities can be maximized.
  • the electromechanical, in particular piezoelectric, properties of the ferroelectret multilayer composites and electromechanical transducers produced by the method according to the invention can be adapted by selecting the shape, size and shape of the cavities, their number, arrangement and / or distribution.
  • the cavities may be in shapes with a rather small area, such as lines, such as curved or straight, single or crossed lines or perimeter lines of geometric figures, such as a circle or perimeter of a cross, or as structures with a larger area, such as rectangles, circles , Crosses, et cetera, be trained.
  • the shape and dimensioning of the cavities is preferably set in such a way that the polymer films can not touch perpendicularly to their layer course within the cavity and / or that the total void volume resulting after completion is as large as possible.
  • the positive and negative charges applied by polarity to the inner surfaces of the cavities should not be able to touch.
  • the cavities may be formed into shapes having a cross-sectional area selected from the group consisting of substantially circular, for example, circular, elliptical or oval, polygonal, for example triangular, rectangular, trapezoidal, diamond-shaped, pentagonal, hexagonal, in particular honeycomb, cruciform, star-shaped and partially round and partially polygonal, for example S-shaped, cross-sectional areas.
  • the cavities in different layers between the different polymer films in the Film stacks can be configured the same or different. This includes both their shape, size and shape as well as the number of cavities, their arrangement and / or distribution.
  • the voids within the formed polymer film composite can advantageously soften the ferroelectret multilayer composite to be made along its thickness, thereby lowering its modulus of elasticity, as well as allowing a poling process in the resulting voids.
  • the cavities in the polymer film composite formed may be formed both homogeneously and heterogeneously distributed.
  • the bonding of the polymer films to a polymer film composite in step c) can be carried out according to the invention, for example by lamination, gluing, stapling, clamping, screwing, riveting or welding (eg laser welding, ultrasonic welding, vibration welding).
  • the bonding of the polymer films by lamination may in particular be carried out thermally, under elevated pressure and / or by means of ultrasound and / or by irradiation with ultraviolet light or infrared light.
  • the choice of material for the polymer films can be increased.
  • the conditions for the lamination are expediently chosen so that the film layers combine, but the structuring of the first polymer film and its height profile are retained as far as possible, thereby ensuring dimensional stability and defined formation of the cavities.
  • the material of the first structured polymer film and / or the material of the second polymer film which in other words forms a cover of the first film, may be completely solidified, for example completely dried and / or completely crosslinked, and / or completely solidified and / or or completely crystallized.
  • the dimensional stability of the method according to the resulting, cavities comprehensive polymer film composite can be improved.
  • connection of the polymer films in step c) by means of an adhesive bond can be carried out, for example, with acrylate adhesive.
  • the polymer material becomes in place and / or Regions where the solvent has been applied dissolved and cured again by the evaporation of the solvent and can serve in this way as an adhesive between the polymer films.
  • Advantage in the connection by this solvent method is that no thermal stress occurs and improves the dimensional stability especially in thermally deformable polymer materials and collapse of the formed cavities can be avoided.
  • the polymer films can also be bonded to one another by lamination in addition to the lamination.
  • This bond can be produced for example by means of acrylate adhesive.
  • the application of electrodes to the outer surfaces of the polymer film composite is understood to mean the provision of a conductive surface coating in at least one partial region, in particular on the outwardly directed surfaces of the polymer composite.
  • the electrodes are preferably arranged on compact or non-structured surfaces of the polymer films used.
  • a polarity of the opposite sides of the cavities can be realized for example by a corona discharge.
  • a corona treatment is advantageously also suitable for large-scale use.
  • the ferroelectret multi-layer composites produced according to the invention can have at least partially a conductive coating on the outwardly directed surfaces of the polymer films. These conductive areas can be used as electrodes.
  • the conductive coating that is to say the electrodes, can be applied in a planar and / or structured manner. For example, a patterned conductive coating may be configured as an application in stripes or in lattice form. In this way, in addition, the sensitivity of the ferroelectret multi-layer composite can be influenced and adapted to specific applications.
  • the selected electrode materials may be conductive materials known to those skilled in the art.
  • metals, metal alloys, conductive oligo- or polymers such as polythiophenes, polyanilines, polypyrroles, conductive oxides, such as mixed oxides such as ITO, or polymers filled with conductive fillers
  • Suitable fillers for polymers filled with conductive fillers are, for example, metals, conductive carbon-based materials such as carbon black, carbon nanotubes (CNTs) or, in turn, conductive oligomers or polymers.
  • the filler content of the polymers is above the percolation threshold, so that the conductive fillers form continuous electrically conductive paths.
  • the electrodes can be prepared by methods known per se, for example by metallization of the surfaces, by sputtering, vapor deposition, chemical vapor deposition (CVD), printing, knife coating, spin coating, gluing or pressing a conductive layer in prefabricated form or by a spray electrode made of a conductive plastic can be realized.
  • the electrodes can be structured, for example in stripes or in lattice form, be configured.
  • the electrodes can also be structured in such a way that the ferroelectret multilayer composite has active and passive regions as an electromechanical transducer.
  • the electrodes can be structured in such a way that, in particular in a sensor mode, the signals are detected spatially resolved and / or, in particular in an actuator mode, the active regions can be specifically controlled. This can be achieved, for example, by providing the active regions with electrodes, whereas the passive regions have no electrodes.
  • two or more ferroelectret multi-layer composites can be connected to the same polarized conductive layer, that is to say electrode.
  • an intermediate electrode can be formed, which can be switched against the two electrodes on the then outer surfaces.
  • the ferroelectret multi-layer composites can be connected in series and the achievable piezoelectric effect can be doubled or multiplied.
  • the ferroelectret multi-layer composites according to the invention preferably contain two electrodes.
  • the electromechanical transducers according to the invention having more than two electrodes can be, for example, stack constructions of a plurality of preferably prepared according to the invention, ferroelethricate multilayer composite systems.
  • the steps a), b), c) and / or d) can be carried out as a continuous roll-to-roll process.
  • the production of the multilayer composites can therefore be at least partially continuous Process, preferably as a roll-to-roll process, to be performed. This is particularly advantageous for the application of the processes on an industrial and industrial scale.
  • the automation of at least part of the manufacturing processes simplifies the processes and enables the low-cost production of the multi-layered ferroelectret composite with cavities. According to the invention, all steps of the method are advantageously accessible to automation.
  • the second polymer film prior to step b), can also be structured to form a height profile.
  • the selected total number of polymer films and the selected sequence of structured and unstructured polymer films can be used to determine the overall height and the number of cavities or number of cavities.
  • two, three or more polymer films with intervening cavities can thus be arranged one above the other and joined together.
  • structured and non-structured polymer films can be arranged alternately one above the other in the film stack.
  • all the polymer films used can also have a height profile, wherein the films can have the same or a different structuring with respect to one another.
  • the sealing of the edges of the polymer film composite formed in step c) is included in a further step e) before or after the charging in step d).
  • the multilayer composites of the invention can thus be advantageously sealed at the edges to hermetically protect them from environmental influences, for. For example, in applications in an aggressive environment, for example, in atmospheres with high humidity or under water.
  • a gas can be introduced into the cavities.
  • the gas may be, for example, pure nitrogen (N 2 ), nitrogen oxide (N 2 O) or sulfur hexafluoride (SF 6 ).
  • N 2 pure nitrogen
  • N 2 O nitrogen oxide
  • SF 6 sulfur hexafluoride
  • Another object of the present invention is a multi-layered ferroelectret composite comprising a layer stack of at least one first polymer film, and one with this connected second polymer film, wherein at least the first polymer film at least on its side facing the second polymer film surface has a structure with elevations and depressions and the first polymer film is formed with its formed by structuring height profile with the second polymer film so that between the polymer films one or more Hollows are formed and further provided the inner surfaces of the cavities with opposite electrical charges.
  • the cavities may be formed in shapes having a cross-sectional area in the direction of the layer course of the polymer films selected from the group consisting of substantially round, for example circular, elliptical or oval, polygonal, for example triangular, rectangular, trapezoidal, diamond-shaped, pentagonal, hexagonal, in particular honeycomb-shaped, cross-shaped, star-shaped and partially round and partially polygonal, for example S-shaped, have cross-sectional surfaces, as well as be completely formed in deviating forms.
  • the geometric shapes can continue to be configured regularly and irregularly.
  • the cavities perpendicular to the layer course of the polymer films in the film stack may be formed partially or completely in forms which have a cross-sectional area selected from the group consisting of essentially round, for example circular, elliptical or oval, polygonal, for example triangular, rectangular, trapezoidal, diamond-shaped, pentagonal, hexagonal, in particular honeycomb-shaped, cruciform, star-shaped and partially round and partially polygonal, for example, S-shaped, cross-sectional surfaces, have, as well as be completely formed in deviating forms.
  • the geometric shapes can continue to be configured regularly and irregularly.
  • the ferroelectret multi-layer composites according to the invention can have cavities which, partially or completely, have no purely bubble-shaped or dome-shaped form, in particular with a rectangular base.
  • the deviating erf ⁇ ndungshiel possible shapes of the cavities allow variable adjustment of the essential properties of the resulting multilayer composites, such as the piezoelectric constant or the elasticity and softness of the multi-layer composite along its thickness and thus a wide range of applications.
  • the cavities and their distribution advantageously, the total void volume of the ferroelectret multi-layer composite can be optimized.
  • the multilayer composite according to the invention can also contain more than two polymer films and correspondingly also multiple layers of cavities contain the same or different ones Shape, dimensioning, number and distribution of cavities may have.
  • the multilayer composite according to the invention can be provided with electrodes.
  • the invention further relates to a ferroelectret two- or multi-layer composite with cavities produced by a process according to the invention as described above.
  • the various variants of the production process provided and the resulting ferroelectret multilayer composites can also be carried out, if appropriate, in combination with one another.
  • Such two- and multi-layer composites according to the invention have stacked polymer films and at least cavities formed between in each case two polymer films. The polymer films are connected to each other between the cavities.
  • the shape and dimensioning of the cavities can be produced according to the invention very precisely predetermined and defined.
  • the invention further relates to a piezoelectric element containing at least one inventive ferroelectret multilayer composite and / or at least one ferroelectret multilayer composite prepared by the process according to the invention.
  • This piezoelectric element may for example be a sensor, actuator or generator element.
  • the invention in a variety of different applications in the electro-mechanical and electro-acoustic field, in particular in the field of energy from mechanical vibrations (energy harvesting), acoustics, ultrasound, medical diagnostics, acoustic microscopy, mechanical sensors, in particular pressure - Force and / or strain sensors, robotics and / or communication technology can be realized.
  • Typical examples include pressure sensors, electroacoustic transducers, microphones, loudspeakers, vibration transducers, light deflectors, diaphragms, optical fiber modulators, pyroelectric detectors, capacitors and control systems, and "smart" floors.
  • the invention further comprises an apparatus for producing ferroelectret multi-layer composites according to the invention.
  • the invention further relates to an apparatus for carrying out the method according to the invention, wherein the apparatus comprises means for structuring at least one surface of a first polymer film.
  • These means may be, for example, an embossing roll, an embossing punch or a device for deforming by means of pressurization.
  • the invention provides processes for the production of ferroelectret multi-layer composites with cavities, which can be carried out simply and cost-effectively, even on an industrial scale.
  • the ferroelectret multi-layer structures produced by the methods according to the invention can also be produced with a larger number of layers with a precisely defined cavity structure.
  • the ferroelectrons produced according to the invention can be adjusted particularly well to corresponding fields of application.
  • FIG. 1 schematically shows the structuring of a first polymer film having a groove-like structure on a surface by means of an embossing roller.
  • FIG. 2 shows a first polymer film with a groove-shaped structuring introduced on both sides.
  • Fig. 3a in an oblique plan view schematically the preparation of a polymer film composite of a structured film with a second smooth film.
  • Fig. 3b in an oblique plan view schematically the preparation of a polymer film composite of a two-sided textured film with two non-structured films.
  • Fig. 3c in an oblique plan view schematically the preparation of a polymer film composite of a first structured film with a second equally structured film.
  • Fig. 3d in an oblique plan view schematically the preparation of a polymer film composite of two unilaterally structured film with a third unstructured film.
  • Fig. 5 is an enlarged micrograph of a ferroelectret multilayer composite of two polycarbonate films according to the invention.
  • FIG. 1 schematically shows the structuring of a first polymer film 1 with a groove-like structure on a surface by means of an embossing roll 10.
  • embossing roll 10 is understood to mean a roller which, as an embossing tool, can transfer its structure to a polymer film.
  • the polymer film 1 can be passed, for example, directly after the extrusion between the embossing roller 10 and an unstructured guide roller 11.
  • an unstructured plate could be used.
  • the corresponding height profile can be formed on the polymer film 1.
  • a channel-like structure can be formed on the polymer film, wherein the height profile can be formed by parallel spaced apart webs 2 on a straight base 3.
  • the form of structuring shown could, according to a variant of the invention, also be obtained by slot die extrusion with a correspondingly shaped nozzle.
  • the embossing roller used can advantageously also have other embossed structures, which can be matched to the desired shape of the cavities to be formed.
  • the base area 3 of the polymer film 1 forms, on its surface opposite the height profile, the unstructured second surface of the polymer film 1.
  • the webs 2 are configured in the embodiment shown with vertical sides and straight edges.
  • a structured polymer film 1 is connected according to the invention, for example, with a non-structured polymer film 5
  • channel-like cavities 4 with a rectangular cross-section can be formed as shown in FIG. 3a.
  • the groove-like structure is not limited to the embodiment shown, and the depressions may also be formed, for example, with a semicircular cross-section.
  • the invention provides that the outwardly directed surfaces of the finally formed polymer film composite are not structured. Electrodes may then be applied to these non-structured surfaces before and / or after the poling.
  • FIG. 2 shows a first polymer film 1 with a groove-shaped three-dimensional structure formed on both sides, for example by two embossing rolls arranged one above the other
  • embossing rollers 10 can be introduced into the polymer film 1 guided therebetween.
  • the embossing rollers 10 could each be arranged interlocking with a cylinder-like designed structure.
  • the production of such a double-sided structured polymer film for example, by deformation of an optionally heated polymer film under pressurization in a mold with an optionally pre-tempered contour insert done.
  • Polymer film 1 does not set the height profile as shown in Figure 1 on a base 3 of the
  • Polymer film 1 but the polymer film 1 is deformed three-dimensional overall.
  • cavities 4 can be formed by connecting the first polymer film 1 on both sides, each with a non-structured film, to both surface sides of the polymer film 1, as shown in FIG. 3b.
  • the two-sided Structure of the polymer film 1 it is also possible, the two-sided Structure of the polymer film 1 to be designed such that the height profile is formed on both surfaces starting from a base 3.
  • FIG. 3a schematically shows the production of a polymer film composite according to the invention from a structured polymer film 1 produced analogously to the structured polymer film 1 produced in FIG. 1 with a second non-structured polymer film 5.
  • the second polymer film 5 can be applied to the surface of the polymer film
  • the connection of the two polymer films 1 and 5 can be effected by lamination, gluing, stapling, clamping, screwing, riveting or welding (eg laser welding, ultrasonic welding, vibration welding).
  • FIG. 3b schematically shows the production of a polymer film composite according to the invention from the polymer film 1, structured on both sides and illustrated in FIG. 2, with two non-structured polymer films 5 and 5 '.
  • the non-structured polymer films 5 and 5 ' can each be connected in the direction of the arrow on one surface side with the structured polymer film 1 and in each case form a layer of cavities 4 and 4' through the compound.
  • the cavities 4 and 4 ' may each have a rectangular cross-section in the embodiment shown.
  • the cavities 4 and 4 'according to the invention can in principle be configured independently of each other in variable shapes and sizes. This also applies to the cavities 4 or 4 'in one layer of the resulting polymer film composite.
  • cavities within the polymer film composite formed can advantageously soften the ferroelectret multilayer composite to be produced along its thickness, ie perpendicular to the layer course of the polymer films 1, 5, 5 ', in order to reduce its modulus of elasticity and enable a poling process in the resulting cavities.
  • the connection of the two polymer films 1 and 5 can be effected by lamination, gluing, stapling, clamping, screwing, riveting or welding (eg laser welding, ultrasonic welding, vibration welding).
  • the poling can in principle be carried out after the connection of the polymer films, for example by direct charging by application of an electrical voltage to already applied electrodes.
  • a polarity of the opposite sides of the cavities can be realized for example by a corona discharge or a plasma process.
  • FIG. 3c shows schematically the production of a polymer film composite according to the invention from a structured polymer film 1 produced analogously to the structured polymer film 1 produced in FIG. 1 with a second similarly structured polymer film 1 '.
  • Both polymer films 1 and 1 ' have as height profile webs 2 on a base 3.
  • the polymer films 1 and 1 ' can each with their textured surface sides are connected to the formed webs.
  • the webs 2 can be set accurately to one another in the direction of the arrow, with channel-like cavities 4 having a rectangular cross-section perpendicular to the layer course of the polymer films 1 and 1 '.
  • FIG. 3d schematically shows the production of a polymer film composite according to the invention from a structured polymer film 1 produced similarly to the structured polymer film 1 produced in FIG. 1 with a second similarly structured polymer film 1 'and a further non-structured polymer film 5.
  • a second layer of cavities can then be formed.
  • the structured foils 1 and 1 ' are arranged on top of each other with the same orientation of the structure and subsequently joined together.
  • the structures can also be aligned differently.
  • the structures - in this case the webs - could be arranged at an angle of 45 ° or of 90 ° to each other, wherein according to the invention all arrangements in different angles or orientations of the structures to each other are possible.
  • the layer sequence of the polymer films 1 and 1 ' can be variably continued and varied with one or more structured and / or unstructured polymer films.
  • the production of a multi-layered multilayer composite with voids is thus possible in different ways and can optionally be adapted to existing polymer films as precursors or to a planned application and desired properties, such as modulus of elasticity and piezoelectric constants.
  • FIGS. 4a-4g show schematic plan views of various embodiments of embossed structures in polymer films 1 and thus the possible embodiment of the bases of the corresponding cavities transverse to the layer course of the polymer films 1.
  • the structures can, for example, by embossing basically as positive or negative forms, ie as wells or elevations are introduced into a polymer film 1.
  • the illustrated embodiments and configurations of the structuring are only examples and are not intended to limit the invention in any way.
  • FIGS. 4a to 4g only one recess of a mold is identified by way of example by a reference numeral.
  • FIG. 4 a shows a structured polymer film 1 comprising depressions 6, the depressions having a circular base area.
  • the recesses 6 can, as illustrated in FIG. 4 a, moreover be formed as a multiplicity of small depressions 6.
  • FIG. 4b shows a structured polymer film 1 comprising depressions 6, the depressions 6 having an elongated, rectangular base area.
  • FIG. 4c shows a structured polymer film 1 comprising depressions 6, the depressions 6 of which have a cross-shaped base surface.
  • FIG. 4 d shows a structured polymer film comprising different depressions 6, 6 ', the depressions of which partially have a circular base surface 6 and partially a diamond-shaped base surface 6'.
  • FIG. 4 d illustrates that in the case of a homogeneously distributed arrangement of depressions with circular 6 and diamond-shaped 6 'cross-sectional areas, a particularly large total void volume can advantageously be achieved.
  • FIG. 4e shows a polymer film 1 comprising depressions 6, the depressions 6 of which have a honeycomb-shaped base surface.
  • FIG. 4 e illustrates that an arrangement which is based exclusively on depressions 6 with honeycomb-shaped cross-sectional areas can likewise achieve an advantageously large total void volume.
  • FIG. 4f shows a structured polymer film 1 comprising recesses 6, 6 ', 6 "whose structure is formed in different shapes and sizes and which have cruciform 6', 6" and substantially honeycomb surfaces 6.
  • FIG. 4f furthermore shows that the depressions 6, 6 ', 6 "can be distributed in an inhomogeneous manner and can be partially connected to one another.
  • FIG. 4g shows a polymer film 1 comprising depressions 6, the depressions 6 of which are formed by applying a combination of different structures, in particular of hexagons / honeycombs, crosses and points of different point and line thicknesses.
  • FIG. 4g further shows that at least the edge regions of the continuous polymer layer can be formed with a closed structure in order to obtain one or more closed cavities in contact with the continuous polymer layers after completion of the inventive production process. In this way, a continuous cavity can be formed.
  • FIG. 4g further illustrates that in the context of the present invention a structured polymer film 1 with height profile can also be understood as meaning a polymer film which has only one depression 6, which can also be understood as a combination or connection of several depressions.
  • FIG. 5 shows an enlarged micrograph of a ferroelectret multi-layer composite according to the invention of two polycarbonate films in cross-section.
  • the structured polymer film 1 a polycarbonate film (Makrofol Bayer MaterialScience AG) with a thickness of 75 microns, was heated just below the glass transition temperature to 130-140 0 C. Thereafter, the polycarbonate film 1 was pressed with an air pressure of 250 bar on the mold with a groove profile. By the mold, the polycarbonate film 1 was deformed such that formed semi-cylindrical depressions. In this case, on the opposite surface of the polymer film 1, the structure was formed as a half-cylinder-shaped height profile.
  • a smooth polycarbonate sheet 5 of 75 ⁇ m in thickness was overlaid and bonded to the first by lamination. This resulted in cavities 4 with a semicircular cross section perpendicular to the layer course of the polymer films 1 and 5.
  • the cavities 4 had a height of 100 microns in cross section.
  • the compact outer surface of the polymer film 1, which has the elevation, and the outwardly directed non-structured surface of the polymer film 5 were each subsequently provided with an aluminum electrode of 50 nm thickness.
  • the polarity of the inner cavities 4 was carried out by directly applied electrical voltage.
  • the composite produced showed a good piezoactivity which was comparable to the piezoactivity of the samples obtained according to Example 5.
  • a masterbatch with the following composition was prepared:
  • Lubricant additive masterbatch according to Example 1 with a content of 20% by weight and polycarbonate Makrolon 2600 from Bayer MaterialScience AG with a content of 80.0% by weight
  • the equipment used for the production of the films consists of
  • a main extruder with a screw of 105 mm diameter (D) and a length of 4IxD; the screw has a degassing zone;
  • the granules were fed to the hopper of the extruder.
  • the plasticizing cylinder / screw of the extruder the melting and conveying of the material took place.
  • the molten material was fed to the smoothing calender whose rolls had the temperature mentioned in Table 1. On the smoothing calender (consisting of three rolls) was the final shaping and cooling of the film.
  • ACPC Advanced Compound Parabolic Concentrator
  • CPC Compound Parabolic Concentrator
  • ⁇ 1, 2 is the aperture angle in the medium of the left (G 1 ) and right (G 2 ) parabola
  • x is the x coordinate
  • y 1 2 is the y coordinate of the left (yi) and right (y 2 ) parabolas ;
  • the effective acceptance angle of the defined acceptance angles of 0.001% or less shortening of the parabolas in the y-direction to the extent determined by the shortening factor.
  • the roll supporting the ACPC structure may in principle also be made of different materials (medium 1: for example PMMA or polycarbonate).
  • the ACPC area can be used in various environments (medium 2: for example, air or water). That is, medium 1 and medium 2 then enter their refractive indices into the said Fresnel equation.
  • the embossed film was transported through a trigger. Thereafter, a protective film made of polyethylene could be applied on both sides and carried out a winding of the film.
  • a film of 180 ⁇ m thickness of the base layer was obtained, in which on one side the ACPC structure was impressed and on the other side a texturing with a surface roughness R 3 Z of 8 ⁇ m.
  • the height of the ACPC structure starting from the base layer was 73 ⁇ m and the distance was 135 ⁇ m. In other words, there is a distance from valley to valley of 135 microns and in the vertical distance from valley to peak of the mountain of 73 microns.
  • a smooth 20 ⁇ m thick polycarbonate film was placed on the structured side of a 285 ⁇ m thick polycarbonate film provided with the ACPC roll profile as described in Example 1. This film composite was then laminated at 205 ° C. After lamination, the film composite has a layer thickness of 285 ⁇ m. Following the depth profile of the film with roll profile, voids are formed in the polymer film composite of the two polycarbonate films. These cavities have in cross section a height of 40 microns and a width of 25 microns. The distance of the cavities is determined by the embossed roll profile. In which Lamination process, however, the flattened profile slightly flattened so that the cavities are smaller than the height of the original roll profile pretends.
  • the total thickness of the layer stack is smaller than the sum of the layer thicknesses of the individual films before the lamination process.
  • the film composite was subsequently provided on both surfaces with aluminum electrodes of 50 nm thickness.
  • the polarity of the internal cavities was carried out by directly applied electrical voltage of 17 to 19 kV.
  • the piezoelectric effect was measured directly after polarity.
  • a smooth 50 ⁇ m thick polycarbonate film was placed on the profiled side of a film provided with the roll profile with a total thickness of 285 ⁇ m analogously to Example 1. This film composite was then laminated at 205 ° C. After lamination, the film composite has a thickness of 320 ⁇ m. Following the depth profile of the film with roll profile triangular cavities form in the polymer film stack. These cavities have a depth of about 40 microns and a width of 60 microns. The distance of the cavities is determined by the embossed roll profile.
  • the 50 ⁇ m thick polycarbonate layer is pressed into the roll profile so that the cavities are smaller than the height of the original roll profile.
  • the total thickness of the polymer film composite is smaller than the sum of the layer thicknesses of the individual films before the lamination process.
  • the film composite was subsequently provided on both surfaces with aluminum electrodes of 50 nm thickness.
  • the polarity of the internal cavities was carried out by direct applied electrical voltage of 20 kV.
  • the piezoelectric effect was measured directly after polarity. According to this example, four 4 cm x 4 cm samples were prepared, each measured five times. For measurements directly after polarity, the mean values shown in Table 2 were obtained.
  • the roll profile was flattened so that the dimensions of the cavities were smaller than the height of the original roll profile specified.
  • the total thickness of the layer stack was smaller than the sum of the layer thicknesses of the individual films before the lamination process.
  • the film composite was subsequently provided on both outwardly facing surfaces with aluminum electrodes of 50 nm thickness.
  • the polarity of the internal cavities was carried out by direct applied electrical voltage of 20 kV.
  • the piezoelectric effect was measured directly after polarity. According to this example, nine 4 cm x 4 cm samples were prepared and measured. In each case, five measurements of the piezoelectric constants were carried out and the average value formed therefrom.
  • a polycarbonate film (Makrofol Bayer MaterialScience AG) with a thickness of 75 microns was heated just below the glass transition temperature to 130-140 0 C. Thereafter, the polycarbonate film was pressed with an air pressure of 250 bar on the mold with a groove profile.
  • Polycarbonate film adapted to the tool contour and was permanently deformed groove-shaped.
  • the film was deformed in its entirety, so that on a surface a height profile and correspondingly formed on the other surface side of the polycarbonate sheet groillenformige depressions.
  • a smooth polycarbonate film of 75 ⁇ m thickness was placed and bonded to the first by lamination.
  • the cavities had a height of 100 ⁇ m in cross section.
  • the film composite was subsequently provided on both surfaces with aluminum electrodes of 50 nm thickness.
  • the polarity of the internal cavities was carried out by directly applied electrical voltage.
  • the composite produced showed a good piezoactivity which was comparable to the piezoactivity of the samples obtained according to Example 5.
  • An enlarged section of the polymer film composite in the region of a cavity is shown in FIG.
  • An embossing stamp made of aluminum was provided with a groove structure.
  • the grooves have a distance of 1 mm, a depth of 80 microns.
  • a polycarbonate film (Makrofol DE 1-1, 125 ⁇ m thick) was pressed into this embossing die in a hot press, so that the groove structure was raised as a height profile on the polycarbonate film.
  • the following three main components are required for the measuring device: Force generator, force measuring device and charge measuring device.
  • Power generator an electric shaker type 4810 from Brüel & Kja ⁇ r was chosen.
  • the vibration exciter makes it possible to exert a defined force as a function of the input voltage.
  • This vibrator was mounted on a movable platform, the position of which is manually adjustable in the vertical direction. The height adjustment of the vibration exciter is necessary for clamping the samples. In addition, it can be used to set the static pre-pressure required for the measurement.
  • To control the vibration exciter was a function generator DS 345 of Stanford Research Systems used in conjunction with a type 2718 power amplifier from Brüel & Kjaer.
  • the force gauge used was a force sensor Type 8435 from Burster.
  • the force sensor is designed for both pressure and tension measurements in the range of 0 to 200 N. However, the force may only be vertical, so that no lateral force components or torques act on the sensor. To ensure this, the force sensor was provided with a cylindrical pressure guide rail with a stainless steel bolt sliding almost smoothly therein. At the free end of the bolt was a two-centimeter-wide polished plate, which served as a support surface for the samples. The signals from the force sensor are detected by a Burster type 9243 module amplifier and passed on to a G.99 4094 oscilloscope.
  • the charge meter used was a charge amplifier Type 2635 from Brüel & Kjaer.
  • the charge amplifier makes it possible to detect charges up to 0.1 pC.
  • the two sides of the sample must be electrically connected to the charge amplifier.
  • the electrical contact to the lower side of the sample is made possible by the support surface, which in turn is connected to the entire structure.
  • the upper side of the sample was connected to the charge amplifier through the brass pressure-applying punch.
  • the stamp is electrically insulated from the rest of the structure by an attachment made of Plexiglas on the oscillator and connected by a cable to the charge amplifier.
  • the cable should be as thin and soft as possible to withstand mechanical stresses and thus
  • the measured signal is finally passed from the charge amplifier to the oscilloscope.
  • a pre-pressure of 3 N static was set and measured with an amplitude of 1 N (dynamic).

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Abstract

Procédé de fabrication de ferroélectrets à deux couches ou multicouches pourvus de cavités définies, qui consiste (a) à structurer au moins une première surface d'un premier film polymère (1), ce qui permet d'obtenir un relief, (b) à déposer au moins un deuxième film polymère (5, 1') sur la surface structurée, formée à l'étape (a), du premier film polymère, (c) à relier les films polymères (1, 1', 5) pour obtenir un composite de films polymères, avec formation concomitante de cavités (4, 4') et (d) à charger électriquement les surfaces internes des cavités (4, 4') formées à l'étape (c) avec des charges électriques opposées. La présente invention concerne en outre des composites multicouches à ferroélectret, éventuellement fabriqués selon le procédé décrit, comprenant au moins deux films polymères disposés l'un sur l'autre et reliés l'un à l'autre, des cavités étant formées entre lesdits films polymères. Elle concerne encore un élément piézoélectrique contenant un composite multicouche à ferroélectret selon l'invention.
EP09764187A 2008-12-13 2009-11-28 Composite à deux couches ou multicouche à ferroélectret et procédé de fabrication dudit composite Pending EP2376279A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP09764187A EP2376279A2 (fr) 2008-12-13 2009-11-28 Composite à deux couches ou multicouche à ferroélectret et procédé de fabrication dudit composite

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
EP08021693 2008-12-13
EP09009203A EP2286988A1 (fr) 2008-12-13 2009-07-15 Composite ferroélectrique à deux et plusieurs couches et son procédé de fabrication
PCT/EP2009/008479 WO2010066348A2 (fr) 2008-12-13 2009-11-28 Composite à deux couches ou multicouche à ferroélectret et procédé de fabrication dudit composite
EP09764187A EP2376279A2 (fr) 2008-12-13 2009-11-28 Composite à deux couches ou multicouche à ferroélectret et procédé de fabrication dudit composite

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EP2376279A2 true EP2376279A2 (fr) 2011-10-19

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EP09764187A Pending EP2376279A2 (fr) 2008-12-13 2009-11-28 Composite à deux couches ou multicouche à ferroélectret et procédé de fabrication dudit composite

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EP (2) EP2286988A1 (fr)
KR (1) KR101515261B1 (fr)
CN (1) CN102317066B (fr)
CA (1) CA2746482A1 (fr)
TW (1) TW201033008A (fr)
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WO2010066348A3 (fr) 2010-08-12
CN102317066A (zh) 2012-01-11
WO2010066348A2 (fr) 2010-06-17
KR101515261B1 (ko) 2015-04-24
CA2746482A1 (fr) 2010-06-17
TW201033008A (en) 2010-09-16
CN102317066B (zh) 2015-06-03
EP2286988A1 (fr) 2011-02-23
KR20110095943A (ko) 2011-08-25
US20110309716A1 (en) 2011-12-22

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