Fluorine-containing polymer powder and method for production thereof and coated article
AssigneeDaikin Industries, Ltd.
InventorsYasukazu Nakatani, Toshio Miyatani, Koichiro Ogita
Life of this patent
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Abstract
A stabilized fluorine-containing polymer powder having an average particle size of 5 to 100 μm is prepared by contacting a fluorine-containing polymer powder, which is prepared by milling the fluorine-containing polymer and removing fine particles, fibrous particles and coarse particles by classification, with a fluorinating agent so that the total number of unstable terminal groups is decreased to 7 to 50 per 106 carbon atoms. This a fluorine-containing polymer powder achieved a high coating efficiency in an electrostatic coating method and provides a film having good properties such as heat resistance, non-tackiness, low frictional property, chemical resistance, etc.
Claims8
A method for producing a fluorine-containing polymer powder comprising the steps of:
- mixing fluorine-containing polymer powder A which has not been treated with a fluorinating agent with fluorine-containing polymer powder B, which is prepared by contacting fluorine-containing polymer powder A with a fluorinating agent so that the total number of —CH2OH and —COF terminal groups is decreased to 25 or less per 106 carbon atoms, to obtain a mixture of fluorine-containing polymer powders having 7 to 50 of —COOH, —COOCH3, —CH2OH and —COF terminal groups per 106 carbon atoms,
- increasing a density of the fluorine-containing polymer powder 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 to 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 to 20% of the whole particle size distribution.
A method for producing a fluorine-containing polymer powder comprising the steps of:
- mixing fluorine-containing polymer powder A which has not been treated with a fluorinating agent with fluorine-containing polymer powder B, which is prepared by contacting fluorine-containing polymer powder A with a fluorinating agent so that the total number of —CH2OH and —COF terminal groups is decreased to 25 or less per 106 carbon atoms, to obtain a mixture of fluorine-containing polymer powders having 7 to 50 of —COOH, —COOCH3, —CH2OH and —COF terminal groups per 10 carbon atoms,
- increasing a density of the fluorine-containing polymer powder 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 to 40% of the whole particle size distribution of the milled mixture,
- classifying the residual mixture to remove coarse particles in an amount of 1 to 20% of the whole particle size distribution,
- and
- heat treating the residual fluorine-containing polymer powder at a temperature equal to or higher than the melting point of the polymer powder.
A method for producing a fluorine-containing polymer powder comprising the steps of:
- mixing fluorine-containing polymer powder A which has not been treated with a fluorinating agent with fluorine-containing polymer powder C, which is prepared by contacting fluorine-containing polymer powder A with a fluorinating agent so that the total number of —CH2OH and —COF terminal groups is decreased to 25 or less per 106 carbon atoms and then contacting the fluorine-containing polymer with ammonia gas to convert the —COF groups to —CONH2 groups, to obtain a mixture of fluorine-containing polymer powders having 50 or less of —COOH, —COOCH3, —CH2OH, —COF and —CONH2 terminal groups per 106 carbon atoms,
- increasing a 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 residual mixture to remove coarse particles in an amount of 1 to 20% of the whole particle size distribution.
A method for producing a fluorine-containing polymer powder comprising the steps of:
- mixing fluorine-containing polymer powder A which has not been treated with a fluorinating agent with fluorine-containing polymer powder C, which is prepared by contacting fluorine-containing polymer powder A with a fluorinating agent so that the total number of —CH2OH and —COF terminal groups is decreased to 25 or less per 106 carbon atoms and then contacting the fluorine-containing polymer with ammonia gas to convert the —COF groups to —CONH2 groups, to obtain a mixture of fluorine-containing polymer powders having 50 or less of —COOH, —COOCH3, —CH2OH, —COF and —CONH2 terminal groups per 106 carbon atoms,
- increasing a 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 residual mixture to remove coarse particles in an amount of 10 to 20% of the whole particle size distribution, and
- heat treating the residual fluorine-containing polymer powder at a temperature equal to or higher than a melting-initiation temperature of the polymer powder.
Dependencies are inferred from the claim text.