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

Claim 16:
17. 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 further includes at least one filter BD that is disposed on the downstream side of the filter A on the flow path and has a pore size smaller than a pore size of the filter A,
the filter 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,
the filter B includes at least one filter BU that is disposed on an upstream side of the filter A on the flow path and has a pore size larger than a pore size of the filter A, 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 the filter BU from a downstream side of the filter A on the flow path.