Patent ID: 11878274
Assignee: FUJIFILM CORPORATION
Field: Chemical engineering (Chemistry)
Classification: CPC B  G | IPC B

Claim 0:
1. A filtering device for obtaining a chemical liquid by purifying a liquid to be purified, the filtering device comprising:
an inlet portion;
an outlet portion;
a filter A;
at least one filter B different from the filter A;
a flow path which includes the filter A and the filter B arranged in series and extends from the inlet portion to the outlet portion; and
a return flow path,
wherein the filter A is a porous membrane containing a polyimide-based resin,
the filter B includes two or more filters BD that are disposed on a downstream side of the filter A on the flow path and have a pore size smaller than a pore size of the filter A,
the filter B further includes two or more filters BU that are disposed on an upstream side of the filter A on the flow path and have a pore size larger than the pore size of the filter A,
the two or more filters BU include at least one filter that contains a resin having an ion exchange group,
at least one of the two or more filters BD includes a first resin including at least one resin selected from the group consisting of polyolefin, polyamide, polyfluorocarbon, polystyrene, and polyethersulfone, and a second resin having at least one hydrophilic group, and

the return flow path is configured to return the liquid to be purified to the upstream side of the filter A and a downstream side of at least one of the two or more filters BU from the downstream side of the filter A on the flow path.