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AssigneeAsahi Glass Company, Limited
InventorsSusumu SAITO, Wakako HASHIMOTO, Tetsuji SHIMOHIRA, Kazuo HAMAZAKl, Satoshi OTSUGU, Hiroki MATOBA
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To provide a method capable of producing fluorinated polymer particles in which formation of fine particles or formation of large aggregates is sufficiently suppressed even in the case of a fluorinated polymer having high solubility in a solvent. The method comprises the following steps (i) and (ii), being a method for producing particles of a fluorinated polymer (A) which has either one or both of structural units (u1) derived from tetrafluoroethylene and structural units (u2) having no sulfonic acid type functional group and having a cyclic structure and fluorine atoms, and which has structural units (u3) having a sulfonic acid type functional group, wherein the proportion of the structural units (u1) is from 0 to 82 mol % in all structural units (100 mol %) in the fluorinated polymer (A): (i) a step of preparing solution or dispersion of the fluorinated polymer (A) having the above fluorinated polymer (A) dissolved or dispersed in a solvent (B), wherein the following conditions (i-1) and (i-2) are satisfied: (i-1) the solvent (B) contains a good solvent (B2) wherein the solubility of the fluorinated polymer (A) is at least 30%, (i-2) even when the above solution or dispersion of the fluorinated polymer (A) is passed through a filter of 200 mesh made of stainless steel, no residue remains on the filter, (ii) a step of mixing the above solution or dispersion of the fluorinated polymer (A) and a solvent (C) to aggregate the fluorinated polymer (A) to form particles of the fluorinated polymer (A), wherein the following conditions (ii-1) to (ii-3) are satisfied: (ii-1) the solvent (C) contains a poor solvent (C1) whereby the degree of swelling of the fluorinated polymer (A) is at most 100%, (ii-2) the degree of swelling of the fluorinated polymer (A) by a mixed solvent (BC) of the solvent (B) and the solvent (C) is from 70 to 250%, (ii-3) the ratio of the mass (WC) of the solvent (C) to the mass (WB) of the solvent (B) is from 1 to 5.
A method for producing fluorinated polymer particles comprising the following steps (i) and (ii), being a method for producing particles of a fluorinated polymer (A) which has either one or both of structural units (u1) derived from tetrafluoroethylene and structural units (u2) having no sulfonic acid type functional group and having a cyclic structure and fluorine atoms, and which has structural units (u3) having a sulfonic acid type functional group, wherein the proportion of the structural units (u1) is from 0 to 82 mol % in all structural units (100 mol %) in the fluorinated polymer (A):
Dependencies are inferred from the claim text.