Daikin Industries, Ltd.

Emi Kiritani

Kunihiko Inui

Hideyuki Kiyotani

A tetrafluoroethylene polymer is provided in an air filter medium having a pressure loss that can be reduced and made uniform at a plurality of positions. The tetrafluoroethylene polymer may also be provided in an air filter medium, a filter pack, or an air filter unit. The tetrafluoroethylene polymer has drawability and non-melt processability. The tetrafluoroethylene polymer has a ratio S/Sof 0.60 or more, where Srepresents an endotherm mJ/mg in a range of T° C. or higher and 350° C. or lower, T° C. is a temperature 2.5° C. lower than a temperature T° C. (340≤T≤345) at which a minimum point is given on a heat-of-fusion curve obtained by measuring an unbaked polymer for measurement having no history of heating to a temperature of 300° C. or higher using a differential scanning calorimeter at a temperature-increasing rate of 2° C./min, and Srepresents an endotherm mJ/mg in a range of 320° C. or higher and T° C. or lower.

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Osaka, Japan

Emi Kiritani