US 12,167,762 B2
Core-sheath composite fiber for artificial hair, headdress product including same, and production method therefor
Norikazu Yasutomo, Osaka (JP); Genta Sakamoto, Osaka (JP); and Hiroshi Fujinaga, Osaka (JP)
Assigned to KANEKA CORPORATION, Osaka (JP)
Filed by KANEKA CORPORATION, Osaka (JP)
Filed on Aug. 4, 2021, as Appl. No. 17/393,818.
Application 17/393,818 is a continuation of application No. PCT/JP2020/001144, filed on Jan. 16, 2020.
Claims priority of application No. 2019-025699 (JP), filed on Feb. 15, 2019.
Prior Publication US 2021/0361011 A1, Nov. 25, 2021
Int. Cl. A41G 3/00 (2006.01); A41G 5/00 (2006.01); D01F 8/12 (2006.01); D01F 8/14 (2006.01)
CPC A41G 3/0083 (2013.01) [A41G 5/004 (2013.01); D01F 8/12 (2013.01); D01F 8/14 (2013.01); D10B 2503/08 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A core-sheath conjugate fiber for artificial hair comprising a core part and a sheath part,
wherein the core-sheath conjugate fiber for artificial hair has a flat multilobed cross sectional shape, and has a core-to-sheath area ratio on a fiber cross section in a range of 2:8 to 9:1,
a viscosity ratio a/b between a melt viscosity a of a core part resin composition and a melt viscosity b of a sheath part resin composition is 2.0 or more and 7.0 or less,
the core part of the core-sheath conjugate fiber for artificial hair has the flat multilobed cross sectional shape, and a major axis direction of the fiber cross section and a major axis direction of the core part cross section match each other,
the flat multilobed cross sectional shape is a flat two-lobed shape in which two circular and/or elliptical portions are connected via recesses,
a length Lc of a major axis of the core part cross section and a length Sc1 of a first minor axis of the core part cross section satisfy equation (2) below, and
the major axis of the core part cross section is a straight line with a largest length among an axisymmetric axis and straight lines connecting any two points on an outer circumference of the core part cross section so as to be in parallel to the axisymmetric axis, and the first minor axis of the core part cross section is a straight line connecting two points so as to have the largest length when connecting any two points on the outer circumference of the core part cross section so as to be perpendicular to the major axis of the core part cross section,
Lc/Sc1=1.1 or more and 2.0 or less  (2).