	US 12,460,055 B2
	Low-molecular-weight polytetrafluoroethylene production method and powder
Chisato Iguchi, Osaka (JP); Eiji Masuda, Osaka (JP); Masayuki Tsuji, Osaka (JP); Akira Shimodo, Osaka (JP); Jirou Hiromoto, Osaka (JP); and Shigeki Santou, Osaka (JP)
Assigned to DAIKIN INDUSTRIES, LTD., Osaka (JP)
Filed by DAIKIN INDUSTRIES, LTD., Osaka (JP)
Filed on Jul. 8, 2022, as Appl. No. 17/860,799.
Application 17/860,799 is a continuation of application No. PCT/JP2021/000244, filed on Jan. 6, 2021.
Claims priority of application No. 2020-002283 (JP), filed on Jan. 9, 2020; and application No. 2020-040675 (JP), filed on Mar. 10, 2020.
Prior Publication US 2022/0363845 A1, Nov. 17, 2022
Int. Cl. C08J 3/28 (2006.01); C08F 114/26 (2006.01)

CPC C08J 3/28 (2013.01) [C08F 114/26 (2013.01); C08J 2327/18 (2013.01)]

4 Claims

1. A method for producing low-molecular-weight polytetrafluoroethylene, the method comprising:

(1) irradiating polytetrafluoroethylene containing a C4-C16 perfluorocarboxylic acid or any salt thereof and having a heat-of-fusion reduction of 40% or lower between first heating and second heating in differential scanning calorimetry with radiation to a dose of 5 to 1000 kGy substantially in the absence of oxygen at a temperature of lower than 100° C. to provide low-molecular-weight polytetrafluoroethylene containing a reduced amount of the perfluorocarboxylic acid and any salt thereof and having a melt viscosity at 380° C. of 1.0×10²to 7.0×10⁵Pa·s.