SOLUTION OR SUSPENSION OF FLUOROPOLYMERS, PROCESS FOR MAKING THEM AS WELL AS THEIR USE FOR THE PREPARATION OF PIEZOELECTRIC AND PYROELECTRIC LAYERS

摘要

Producing a homogeneous solution of a fluoropolymer of fluoro homopolymers and/or fluoro-copolymers in a high boiling solvent, comprises (a) dissolving fluoropolymer to be dissolved in a mixture of at least two solvents, where the first solvent comprises a boiling point of below 150[deg] C and/or a vapor pressure of above 5 hPa at 20[deg] C, and the second solvent is a high boiling solvent, and subsequently (b) substantially or completely removing the first solvent from the mixture. Producing a homogeneous solution of a fluoropolymer of fluoro homopolymers and/or fluoro-copolymers in a high boiling solvent, comprises (a) dissolving fluoropolymer to be dissolved in a mixture of at least two solvents, where the first solvent comprises a boiling point of below 150[deg] C and/or a vapor pressure of above 5 hPa at 20[deg] C, and the second solvent is a high boiling solvent, which is selected such that the boiling point of second solvent is at least 50[deg] K higher than the first solvent and/or the solvent mixture has a separation factor of alpha >= 1 and subsequently (b) substantially or completely removing the first solvent from the mixture. Independent claims are also included for: (1) preparing a suspension of inorganic particles of a piezoelectric and pyroelectric active or activatable oxide in a homogeneous solution of a fluoropolymer, comprising (i) preparing a suspension of inorganic particles in a suspending agent, (ii) preparing a fluoropolymer solution as mentioned above, (iii) adding the suspension of the inorganic particles to the solution of fluoropolymers according to (ii), and (iv) substantially or completely removing the suspending agent; (2) a colorless homogeneous solution of a fluoropolymer, comprising the solvent which is not assessed as toxic for reproduction and has a lethal dose (LD50) of >= 200 mg/kg), measured in a rat; and (3) a colorless suspension of inorganic particles of a piezoelectric and pyroelectrically active or activatable oxide in a homogeneous solution of a fluoropolymer obtained by the above process.