US 12,152,093 B2
Tetrafluoroethylene polymer, air filter medium, filter pack, and air filter unit
Emi Kiritani, Osaka (JP); Kunihiko Inui, Osaka (JP); and Hideyuki Kiyotani, Osaka (JP)
Assigned to DAIKIN INDUSTRIES, LTD., Osaka (JP)
Appl. No. 17/312,045
Filed by DAIKIN INDUSTRIES, LTD., Osaka (JP)
PCT Filed Dec. 6, 2019, PCT No. PCT/JP2019/047961
§ 371(c)(1), (2) Date Jun. 9, 2021,
PCT Pub. No. WO2020/121981, PCT Pub. Date Jun. 18, 2020.
Claims priority of application No. 2018-230700 (JP), filed on Dec. 10, 2018.
Prior Publication US 2021/0388127 A1, Dec. 16, 2021
Int. Cl. B01D 39/00 (2006.01); B01D 39/08 (2006.01); B01D 39/16 (2006.01); B01D 46/52 (2006.01); C08F 14/26 (2006.01)
CPC C08F 14/26 (2013.01) [B01D 39/083 (2013.01); B01D 39/16 (2013.01); B01D 46/52 (2013.01); B01D 2201/12 (2013.01); B01D 2257/204 (2013.01); C08J 2327/18 (2013.01)] 13 Claims
OG exemplary drawing
 
1. An air filter medium, comprising:
a tetrafluoroethylene-polymer-drawn-porous-film having a thickness of 15.0 μm or less, and having a coefficient of variation of pressure loss of 5.0 or less,
wherein the tetrafluoroethylene polymer has drawability and non-melt processability,
wherein the tetrafluoroethylene polymer has a standard specific gravity of 2.158 or more,
wherein the tetrafluoroethylene polymer has a ratio S2/S1 of 0.70 or more and 0.90or less, where S2represents an endotherm mJ/mg in a range of T0° C. or higher and 350° C. or lower, T0° C. is a temperature 2.5° C. lower than a temperature Tp° C. (340≤Tp≤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 S1 represents an endotherm mJ/mg in a range of 320° C. or higher and T0° C. or lower, and
in the heat-of-fusion curve, a half-width HW that is a difference between temperatures at two intersection points of the heat-of-fusion curve and a line which is parallel to a baseline and passes through a half position of a vertical line extending from the minimum point at the temperature Tp° C. to the baseline is 6.0 or more.