Classifications

• • 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
  • 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
  • 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
  • B32B3/10—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 discontinuous layer, i.e. formed of separate pieces of material
  • B32B3/18—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 discontinuous layer, i.e. formed of separate pieces of material characterised by an internal layer formed of separate pieces of material which are juxtaposed side-by-side
  • B32B3/20—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 discontinuous layer, i.e. formed of separate pieces of material characterised by an internal layer formed of separate pieces of material which are juxtaposed side-by-side of hollow pieces, e.g. tubes; of pieces with channels or cavities
• • 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
  • H10N30/08—Shaping or machining of piezoelectric or electrostrictive bodies
  • H10N30/084—Shaping or machining of piezoelectric or electrostrictive bodies by moulding or extrusion
• • 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
• • 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
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/249921—Web or sheet containing structurally defined element or component
  • Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]
  • Y10T428/24996—With internal element bridging layers, nonplanar interface between layers, or intermediate layer of commingled adjacent foam layers

Definitions

• the present invention relates to a polymer structure with ferroelectret properties having a first continuous polymer layer and a second continuous polymer layer, wherein the first and the second polymer layers are connected to each other by connecting portions arranged inclined to the continuous polymer layers to form cavities. Furthermore, the present invention relates to a method for producing a polymer layer composite according to the invention and a piezoelectric element comprising a polymer layer composite according to the invention. Because of their advantageous and specifically adjustable properties, such as low weight, thermal conductivity, mechanical deformability, electrical properties and barrier functions, polymer 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.
• Piezoelectric materials are capable of 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 the transducer geometry.
• Piezoelectric materials are already being integrated as active components in a variety of applications. These include, for example, structured pressure sensors for keyboards or touchpads, acceleration sensors, microphones, loudspeakers, ultrasonic transducers for applications in medical technology, marine technology or materials testing.
• the patent application WO 2006/053528 A I describes an electroacoustic transducer based on a piezoelectric element made of polymer films.
• ferroelectrets are polymer materials with a cavity structure that can store electrical charges for 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.
• the ferroelectrets can exhibit a piezoelectric activity comparable to that of other piezoelectrics.
• Ferroelectrets continue to be of increasing interest to commercial applications such as sensor, actuator and generator systems. In the case of hostility, the applicability of a production process on an industrial scale is essential.
• foamed ferroelectret polymer films are to directly physically foam a homogenous film with supercritical fluids, such as carbon dioxide.
• supercritical fluids such as carbon dioxide.
• Gerhard I Zirkel Cellular Polyethylene Naphthalate Ferroelectrets: Foaming in Supercritical Carbon Dioxide, Structural and Electrical Preparation, and Resulting Piezoelectricity
• Applied Physics A Materials Science & Processing 90, 615-618 (2008), O. Voronina, M. Wegener, W. Wirges, R. Gerhard, L. Zirkel and 1.
• the foamed polymer films have the disadvantage that a broad distribution of the bubble size can result. As a result, not all bubbles can be charged equally well in the subsequent charging step.
• WO 2010/066348 A2 discloses a method for the production of two- or multi-layer ferroelecates with defined cavities by structuring at least one first surface of a first polymer film to form a height profile, placing at least one second polymer film on the one formed in a first step structured surface of the first polymer film, joining the polymer films to a polymer film to form cavities and electrifying the inner surfaces of the formed cavities with opposite electrical charges.
• the patent application relates to a piezoelectric element comprising a ferroelectret multi-layer composite of the invention.
• Structural structures can be generated, the method should be particularly simple and inexpensive to be carried out on a large scale and industrial scale.
• the present invention thus relates to a polymer structure with ferroelectret properties.
• the polymer layer structure comprises a continuous first polymer layer and a continuous second polymer layer, wherein the first and the second polymer layer are connected to each other by connecting portions arranged between the continuous polymer layers to form cavities.
• the polymer layer structure is characterized in that it is designed as an integral extrusion component.
• an "integral extrusion component” is understood as meaning those components which obtain their required shape for the particular application directly from the extrusion step, ie, apart from possibly necessary post-processing to ensure a consistently high product quality, further shaping steps or Joining steps are necessary, in particular an integral extrusion components requires no connection of individual component components following the extrusion.
• ferroelectret properties mean that within electric cavities opposite electric charges are arranged on opposite surfaces of the cavity. As already stated, each cavity thus constitutes an electric dipole. When the cavity is deformed, the dipole size changes and an electric current can flow between correspondingly connected external electrodes.
• the particular advantage of the polymer structure according to the invention is that it can be produced in a cost-effective manner with a high degree of automation by means of an established production process, namely by means of extrusion, in a cost-effective manner.
• the extrusion allows a high degree of design freedom.
• a large number of cross-sectional geometries can be realized with a corresponding nozzle shape.
• the cavities are due to the process over the entire Warr corner of the extruded polymer layer structure tunnel-like with a constant cross-section, so as arranged in parallel, linear, continuous channels formed.
• the first and the second polymer layer of the polymer layer structure may be formed with variable thickness, in particular with periodically varying thickness.
• the thicknesses d 1 and d 2 of the first and second polymer layers are constant.
• the term "constant” is to be understood according to the invention that the thickness varies at most by + 10% due to unavoidable fluctuations, with variations of at most ⁇ 5% of the thickness being preferred.
• di e cavities at least partially have a trapezoidal cross-section, in particular a symmetrical trapezoidal cross-section with equal legs on. It is preferred that all cavities have a, in particular symmetrical, trapezoidal cross-section, wherein in horizontally arranged polymer layer structure in each case the longer base side of a trapezoidal cross-section is arranged alternately above and below the associated shorter base side.
• the trapezoidal cross sections of respectively adjacent cavities can be converted into one another by a point mirroring.
• the connecting sections connecting the two continuous polymer layers can be formed with a thin wall thickness, since the so-called Legs of adjacent Trapezqueritese can be aligned parallel to each other. This contributes to the desired structure softness of the polymer layer structure.
• adjacently arranged connecting sections are arranged at an acute angle to each other and to the two polymer layers. This further contributes to the desired structural softness, whereby the polymer layer structure has a larger piezoelectric constant d 33 , among other things than comparable ferroelectret systems having rectangular cavity cross-sections.
• each obtuse angle has two adjacent acute angles and each acute angle has two adjacent obtuse angles.
• the connecting portions connecting the two continuous polymer layers are tilted in the same direction of rotation with respect to the shortest connection of the two continuous polymer layers.
• the connection sections are thus arranged "in the same direction". It is particularly preferred in this case that the trapezoidal cross-section is formed parallelogram-shaped, wherein the connecting portions have a uniform length and the continuous polymer layers are arranged parallel to each other, especially in the case of parallelogram-shaped cross-sections, a good structure softness is achieved.
• the thickness dl of the first polymer layer is> 10 ⁇ m to ⁇ 250 ⁇ m and the thickness d2 of the second polymer layer is> 10 ⁇ m to ⁇ 250 ⁇ m.
• the width defined as the length of the longer base side of a trapezoidal cross-section is a> 10 ⁇ m to ⁇ 5 mm. preferably> 100 ⁇ to ⁇ 3 mm, is.
• the width b defined as the width of the trapezoidal cross section at half the height is preferably> 10 ⁇ m to ⁇ 5 mm, preferably> 100 ⁇ m to ⁇ 3 mm.
• the height h of the trapezoidal cross section is preferably> 10 ⁇ to ⁇ 500 ⁇ .
• the included between the longer base side of the trapezoidal cross-section and a leg angle ⁇ is preferably> 5 ° to ⁇ 80 °.
• the polymer layer structure comprises a material selected from the group comprising polycarbonate, perfluorinated or partially fluorinated polymers and copolymers, polytetrafluoroethylene, fluorinated ethylene propylene, perfluoroalkoxyethylene, polyester, polyethylene terephthalate, polyethylene naphthalate, polyimide, polyetherimide, polyether.
• PPE poly (phenylene ether)
• PPE polymethyl (meth) acrylate
• cyclo-olefin polymers especially polypropylene, polystyrene and / or mixtures thereof.
• the mixtures can be homogeneous or phase-separated.
• the inventively wide selection of materials can advantageously also allow adaptation to certain applications.
• the tunnel-like cavities of the polymer layer structure produced by extrusion are filled with gases which are selected from the group consisting of nitrogen (N 2 ), nitrous oxide (N 2 O) and / or sulfur hexafluoride (SF 6 ).
• gases which are selected from the group consisting of nitrogen (N 2 ), nitrous oxide (N 2 O) and / or sulfur hexafluoride (SF 6 ).
• the polymer layer structure furthermore comprises one or more electrodes.
• the polymer layer structure according to the invention may 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.
• a patterned conductive coating may be configured as an application in stripes or in lattice form.
• 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, Polyaniiine, Polyp yrrole, conductive oxides, such as mixed oxides such as ITO, or filled with conductive fillers polymers come into question.
• Suitable fillers for polymers filled with conductive fillers are, for example, metals, conductive carbon-based materials, such as, for example, 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 splitting. Vaporizing, Chemical Vapor Deposit (CVD), Printing, Rake! N. Spin coating, sticking or pressing a conductive layer can be realized in prefabricated form or by a spray electrode of a conductive plastic.
• 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 photochemical structure has active and passive regions as an electromechanical transducer.
• the electrodes can be structured in such a way that, particularly in a sensor mode, the signals are detected with local resolution 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 polymer layer structures can be connected to the same-conductive layer, that is to say to the electrode.
• an intermediate electrode can be formed, which can be switched against the two electrodes on the then outer surfaces.
• Electro-mechanical transducers with more than two electrodes can be, for example, staple electrodes made of polymer, preferably layered, polymer layer structure systems, preferably according to the invention.
• the present invention further relates to a process for producing a polymer layer composite according to the invention, comprising the steps:
• the application of electrodes to the outer surfaces of the polymer layer structure can take place before and / or after the electrical charging of the inner surfaces of the cavities in step (C).
• the application of electrodes to the outer surfaces is understood to mean the provision of a conductive surface coating in at least one subregion, in particular on the outwardly directed surfaces of the polymer layer composite.
• the electrical charging takes place in step (C) by means of direct charging or corona discharge.
• the charging can be done by a two-electron corona arrangement.
• the needle voltage can be> 20 kV,> 25 kV and in particular> 30 kV.
• the charging time can be> 20 s,> 25 s and in particular> 30 s.
• direct charging is meant charging when, after the application of electrodes to the outer surfaces of the polymer layer structure, a direct charging takes place by application of an electrical voltage.
• a polling of the opposite sides of the cavities can be realized by a corona discharge.
• a corona treatment is advantageously also suitable for large-scale use. According to the invention, it is also possible first to provide a conductive surface coating on an er surface, then to charge the polymer layer structure and finally to apply a second electrode on the opposite outer surface.
• the cavities are filled with gases which are selected from the group comprising nitrogen, nitrogen monoxide and / or sulfur hexafluoride.
• gases which are selected from the group comprising nitrogen, nitrogen monoxide and / or sulfur hexafluoride.
• gases which are selected from the group comprising nitrogen, nitrogen monoxide and / or sulfur hexafluoride.
• significantly higher piezo constants can be achieved by the gas filling advantageously in the polymer layer composites according to the invention by polarity. It is understood that the cavities extending like a tunnel through the polymer layer structure must be sealed at their end faces, so that the gas filled in remains in the cavities.
• Another object of the present invention is a piezoelectric element comprising a polymer layer structure according to the invention. This piezoelectric element may particularly preferably be a sensor, actuator or generator element.
• the invention can be embodied in a variety of different applications in the electro-mechanical and electro-acoustic field, especially 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.
• 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.
• FIG. 1 shows an extruded polymer layer structure with trapezoidal cavity cross sections in a cross-sectional view.
• FIG. 2 shows an alternative extruded polymer layer structure with parallelogram-shaped cavity cross-sections in a cross-sectional view.
• FIG. 1 shows, for a better understanding, in particular the dimensioning, a polymer layer structure with ferroelectret properties in cross section.
• the polymer layer structure of FIG. 1 comprises a continuous first polymer layer 1, arranged at the top here, and a continuous second polymer layer 2. Both polymer layers 1, 2 have a substantially constant thickness d1. d2, for example, 50 ⁇ , on.
• the two continuous polymer layers 1, 2 are interconnected by angled connecting sections 3 arranged to the continuous polymer layers. Their thickness d3 is preferably also 50 .mu.m.
• tunnel-like cavities 4 are formed, wherein the connecting sections 3 connecting the two polymer layers 1, 2 are arranged at an acute angle to the polymer layers 1, 2 and to each other such that the cavities 4 each have a cross section in the form of a symmetrical trapezoid.
• the longer base side of a trap element is arranged alternately above and below the associated shorter base side, so that in each case adjacent trapezoidal cross sections are aligned with point mirroring one another.
• the angle ⁇ enclosed between the longer base side (base) of each trapezoidal cross section and the adjacent connecting sections can assume values between 5 and 80 °. In the present case, the angle is about 60 °.
• FIG. 2 shows an alternative extruded polymer layer structure with parallelogram-shaped cavity cross-sections 4 * as a special case of trapezoidal cavity cross-sections in a cross-sectional view.
• the connecting sections 3 * here are inclined in the same direction with respect to the imaginary vertical connection of the parallel continuous polymer layers 1, 2. Consequently, the width a, which is no longer explicitly indicated in FIG. 2, also corresponds to the width b at half the height. It is understood that the thicknesses d1, d2 and the angle ⁇ can assume the above-mentioned values.
• FIG. 1 An embodiment in which a plurality of the polymer layer structures shown in Figure 1 are stacked to form a stack, wherein each facing continuous polymer layers of adjacent stacked polymer layer structures are charged with the same polarization.
• electrode layers are arranged between the individual polymer layer structures, which are contacted by the continuous polymer layers of the same polarization.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Laminated Bodies (AREA)
• Extrusion Moulding Of Plastics Or The Like (AREA)

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• 2010
  • 2010-11-03 EP EP20100189897 patent/EP2450974A1/de not_active Withdrawn
• 2011
  • 2011-10-21 TW TW100138200A patent/TW201231284A/zh unknown
  • 2011-10-28 KR KR1020137014034A patent/KR20130108409A/ko not_active Withdrawn
  • 2011-10-28 US US13/883,286 patent/US20140009039A1/en not_active Abandoned
  • 2011-10-28 EP EP11776786.3A patent/EP2636084A1/de not_active Withdrawn
  • 2011-10-28 WO PCT/EP2011/069043 patent/WO2012059437A1/de not_active Ceased
  • 2011-10-28 CN CN2011800533532A patent/CN103460423A/zh active Pending
  • 2011-10-28 JP JP2013537088A patent/JP2013543273A/ja active Pending

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