DIELECTRIC FILM, PROCESS FOR PRODUCING SAME, AND TRANSDUCER USING SAME
A dielectric film which has high electrical resistance and excellent durability and a process for producing the dielectric film are provided. Also provided is a transducer which has large displacement and excellent durability. The dielectric film includes a three-dimensional crosslinked body that is synthesized from an organic metal compound, a rubber polymer that is other than a polydimethyl siloxane and has a functional group that is reactive with the organic metal compound, and an inorganic filler that has a functional group that is reactive with the organic metal compound. The transducer is configured by interposing the dielectric film between at least a pair of electrodes. The dielectric film may be produced by preparing a first solution that contains a rubber polymer and an inorganic filler in a solvent that is capable of dissolving the rubber polymer and of chelating an organic metal compound, then preparing a second solution by mixing the organic metal compound into the first solution, and then removing the solvent from the second solution to allow a crosslinking reaction to proceed.
1 . A dielectric film that is to be interposed between at least a pair of electrodes of a transducer, characterized by comprising a three-dimensional crosslinked body that is synthesized from:
an organic metal compound,
a rubber polymer that is other than a polydimethyl siloxane and has a functional group that is reactive with the organic metal compound, and
an inorganic filler that has a functional group that is reactive with the organic metal compound.
2 . The dielectric film according to claim 1 , wherein the organic metal compound is at least one compound selected from the group consisting of metal alkoxide compounds, metal acylate compounds and metal chelate compounds.
3 . The dielectric film according to claim 1 , wherein the inorganic filler is silica.
4 . The dielectric film according to claim 3 , wherein the silica has a pH of 8.5 or less.
5 . The dielectric film according to claim 1 , wherein the functional group of the rubber polymer is at least one group selected from the group consisting of a carboxyl group, a hydroxyl group, an amino group, an amide, an epoxy group, a thiol and an ester.
6 . The dielectric film according to claim 1 , wherein the rubber polymer is at least one polymer selected from the group consisting of acrylonitrile-butadiene copolymers, hydrogenated nitrile rubbers, acrylic rubbers, urethane rubbers, fluorine rubbers, fluorosilicone rubbers, chlorosulfonated polyethylene rubbers, chloroprene rubbers, ethylene-vinyl acetate copolymers and chlorinated polyethylenes.
7 . The dielectric film according to claim 1 , wherein the organic metal compound contains at least one element selected from the group consisting of titanium, zirconium, aluminum, silicon, boron, vanadium, manganese, iron, cobalt, germanium, yttrium, niobium, lanthanum, cerium, tantalum, tungsten and magnesium.
8 . The dielectric film according to claim 1 , wherein the three-dimensional crosslinked body is synthesized from a composition that includes a plasticizer in addition to the organic metal compound, the rubber polymer and the inorganic filler.
9 . A process for producing a dielectric film as recited in claim 1 , comprising:
a first solution preparing step that prepares a first solution that contains the rubber polymer, the inorganic filler and, optionally the plasticizer in a solvent that is capable of dissolving the rubber polymer and of chelating the organic metal compound,
a second solution preparing step that prepares a second solution by mixing the organic metal compound into the first solution, and
a crosslinking step that removes the solvent from the second solution to allow a crosslinking reaction to proceed.
10 . A transducer characterized by comprising a dielectric film as recited in claim 1 , and a plurality of electrodes that are arranged via the dielectric film.