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.
提供一种生产含
氟聚合物颗粒的方法,在该方法中,即使含
氟聚合物在溶剂中的溶解度很 高,也能充分抑制细小颗粒的形成或大型聚集体的形成。
该方法包括以下步骤(i)和(ii),即生产含
氟聚合物 (A) 颗粒的方法,该含
氟聚合物 (A) 具有衍生自
四氟乙烯的结构单元 (u1) 和不含
磺酸型官能团且具有环状结构和
氟原子的结构单元 (u2) 中的一个或两个、和具有
磺酸型官能团的结构单元(u3),其中结构单元(u1)在含
氟聚合物(A)的所有结构单元(100 摩尔%)中的比例为 0 至 82 摩尔%:
(i) 制备
氟化
聚合物(A)溶液或分散液的步骤,上述
氟化
聚合物(A)溶解或分散于 溶剂(B)中,其中满足以下条件(i-1)和(i-2):
(i-1) 溶剂(B)含有良好溶剂(B2),其中含
氟聚合物(A)的溶解度至少为 30%、
(i-2) 即使上述含
氟聚合物(A)溶液或分散液通过 200 目不锈钢过滤器,过滤器上也没有残留物、
(ii) 将上述含
氟聚合物(A)溶液或分散液与溶剂(C)混合以聚合含
氟聚合物(A)形成含
氟聚合物(A)颗粒的步骤,其中满足以下条件(ii-1)至(ii-3):
(ii-1) 溶剂(C)含有贫溶剂(C1),
氟化
聚合物(A)的溶胀度最多为 100%、
(ii-2) 溶剂(B)和溶剂(C)的混合溶剂(BC)对含
氟聚合物(A)的溶胀度为 70%至 250%、
(ii-3) 溶剂(C)的质量(Wc)与溶剂(B)的质量(WB)之比为 1 至 5。