| 摘要 |
The present invention concerns a method for producing a fluorine-containing polymer powder comprising the steps of:
- mixing a fluorine-containing polymer powder A with
(a) a fluorine-containing polymer powder B prepared by contacting polymer powder A with a fluorinating agent so that the total number of -CH 2 OH and -COF terminal groups is decreased to ‰ 25 per 10 6 carbon atoms, or
(b) a fluorine-containing polymer powder C prepared by contacting polymer powder B with ammonia gas to convert the -COF groups to -CONH 2 groups,
to obtain a mixture of fluorine-containing polymer powders having 50 or less of -COOH, -COOCH 3 , -CH 2 OH, -COF and -CONH 2 terminal groups per 10 6 carbon atoms,
- increasing the density of the fluorine-containing polymer mixture so that a specific gravity reaches at least 90% of the true specific gravity of the fluorine-containing polymer,
- milling the mixture,
- air classifying the milled mixture to remove fine particles and fibrous particles in an amount of 30-40% of the whole particle size distribution of the milled mixture, and
- classifying the residual mixture to remove coarse particles in an amount of 1-20% of the whole particle size distribution;
and further a polymer powder obtainable by to this process, the use of this polymer powder for electrostatic coating, and an article being coated with this polymer powder.
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