Molded article having a reduced metal content obtained from a composition comprising a fluorine-containing elastomer
The present invention concerns a method for preparing a fluorine-containing elastomer, characterized in that any one of the following methods (1) to (8) or by combining two or more thereof are carried out: (1) a metal compound is not blended during emulsion-polymerization of a fluorine-containing mo...
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Sprache: | eng ; fre ; ger |
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Zusammenfassung: | The present invention concerns a method for preparing a fluorine-containing elastomer, characterized in that any one of the following methods (1) to (8) or by combining two or more thereof are carried out:
(1) a metal compound is not blended during emulsion-polymerization of a fluorine-containing monomer,
(2) at least one of materials (excluding a gaseous monomer for polymerization) which are used for polymerization of a fluorine-containing monomer, coagulation and drying contains substantially no metal component,
(3) emulsion-polymerization of the fluorine-containing elastomer is carried out while maintaining an emulsion in a weak alkaline state,
(4) coagulation is carried out after an emulsified dispersion of the fluorine-containing elastomer is filtrated to remove contaminants,
(5) coagulation of an emulsified dispersion of the fluorine-containing elastomer is carried out by using an acid containing no metal element,
(6) to a fluorine-containing elastomer containing water obtained by coagulation of an emulsified dispersion of the fluorine-containing elastomer is added a non-water-soluble solvent which has compatibility with the fluorine-containing elastomer containing water and contains no metal element to separate the water therefrom,
(7) a clean gas is used for drying a fluorine-containing elastomer containing water obtained by coagulation of an emulsified dispersion of the fluorine-containing elastomer or, a coagulated elastomer obtained by adding, to the fluorine-containing elastomer containing water, a non-water-soluble solvent having compatibility therewith and containing no metal element to separate the water therefrom, and
(8) a vessel laminated with a fluorine-containing resin film or polyethylene film on its part coming into contact with the coagulated elastomer, a vessel made of a fluorine-containing resin or a vessel made of polyethylene resin is used,
and said fluorine-containing elastomer has a metal content of not more than 50 ppm. |
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