US 12,006,407 B2
Method for producing low molecular weight polytetrafluoroethylene, low molecular weight polytetrafluoroethylene, and powder
Ken Yoshida, Osaka (JP); Hirotoshi Yoshida, Osaka (JP); Keisuke Hagi, Osaka (JP); Masayuki Tsuji, Osaka (JP); Taketo Kato, Osaka (JP); Yuuji Tanaka, Osaka (JP); Taku Yamanaka, Osaka (JP); Kazuya Kawahara, Osaka (JP); Masamichi Sukegawa, Osaka (JP); and Kazutaka Hosokawa, Osaka (JP)
Assigned to DAIKIN INDUSTRIES, LTD., Osaka (JP)
Filed by DAIKIN INDUSTRIES, LTD., Osaka (JP)
Filed on Jan. 30, 2023, as Appl. No. 18/103,443.
Application 18/103,443 is a continuation of application No. 17/078,365, filed on Oct. 23, 2020.
Application 17/078,365 is a continuation of application No. 16/069,735, granted, now 10,870,735, issued on Dec. 22, 2020, previously published as PCT/JP2017/028469, filed on Aug. 4, 2017.
Claims priority of application No. 2016-153856 (JP), filed on Aug. 4, 2016.
Prior Publication US 2023/0183430 A1, Jun. 15, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. C08J 3/12 (2006.01); C08F 8/06 (2006.01); C08F 8/50 (2006.01); C08F 14/26 (2006.01); C08J 3/28 (2006.01)
CPC C08J 3/12 (2013.01) [C08F 8/06 (2013.01); C08F 8/50 (2013.01); C08F 14/26 (2013.01); C08J 3/28 (2013.01); C08F 2500/07 (2013.01); C08F 2500/17 (2013.01); C08F 2800/20 (2013.01); C08F 2810/40 (2013.01); C08J 2327/18 (2013.01); C08J 2327/22 (2013.01)] 8 Claims
 
1. Powder comprising low molecular weight polytetrafluoroethylene,
the low molecular weight polytetrafluoroethylene having a melt viscosity of 1×102 to 7×105 Pa·s at 380° C., having an average particle size of 1.0 to 50 μm, and containing 30 or more carboxyl groups at ends of the molecule chain per 106 carbon atoms in the main chain,
the powder being substantially free from C8-C14 perfluorocarboxylic acids and salts thereof,
wherein the powder has a specific surface area of not smaller than 0.5 m2/g but smaller than 7.0 m2/g, or not smaller than 9.0 m2/g and not larger than 20 m2/g,
wherein the perfluorocarboxylic acids and salts thereof amount to less than 25 ppb.