US 12,460,099 B2
Reversibly thermochromic composition, reversibly thermochromic microcapsule pigment encapsulating reversibly thermochromic composition, and writing instrument using reversibly thermochromic microcapsule pigment
Hiroshi Umemoto, Aichi-ken (JP); Yui Morigaki, Aichi-ken (JP); and Naoto Masushige, Tokyo-to (JP)
Assigned to THE PILOT INK CO., LTD., Aichi-Ken (JP); and KABUSHIKI KAISHA PILOT CORPORATION, Tokyo-To (JP)
Appl. No. 17/598,478
Filed by THE PILOT INK CO., LTD., Aichi-ken (JP); and KABUSHIKI KAISHA PILOT CORPORATION, Tokyo-to (JP)
PCT Filed Mar. 26, 2020, PCT No. PCT/JP2020/013524
§ 371(c)(1), (2) Date Sep. 27, 2021,
PCT Pub. No. WO2020/203603, PCT Pub. Date Oct. 8, 2020.
Claims priority of application No. 2019-067303 (JP), filed on Mar. 29, 2019.
Prior Publication US 2022/0169919 A1, Jun. 2, 2022
Int. Cl. C09D 11/50 (2014.01); B41M 5/30 (2006.01); B41M 5/327 (2006.01); C09D 11/17 (2014.01); C09D 11/18 (2006.01); C08K 9/10 (2006.01)
CPC C09D 11/50 (2013.01) [B41M 5/305 (2013.01); B41M 5/3275 (2013.01); C09D 11/17 (2013.01); C09D 11/18 (2013.01); C08K 9/10 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A reversibly thermochromic composition comprising:
(a) a fluoran derivative represented by formula (Ia), as an electron-donating color-developing organic compound;
(b) an electron-accepting compound; and
(c) a reaction medium which reversibly induces an electron transfer reaction between the component (a) and the component (b) in a specific temperature range,
wherein formula (Ia) is represented by

OG Complex Work Unit Chemistry
wherein na is 0, 1, or 2, each Ya is independently a halogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, Za is a halogen atom provided that the substitution position of Za is a para position, and each Xa is independently a linear or branched alkyl group having 1 to 8 carbon atoms or a group represented by formula (ia) having 6 to 12 carbon atoms, or
wherein na is 0, 1, or 2, each Ya is independently a halogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, Za is a halogen atom, a liner or blanched alkyl group having 1 to 4 carbon atoms, or a liner or blanched alkoxy group having 1 to 3 carbon atoms, provided that the substitution position of Za is a para position, one of the Xas is a linear or branched alkyl group having 1 to 8 carbon atoms, and the other of the Xas is the group represented by the formula (ia), wherein the formula (ia) is represented by

OG Complex Work Unit Chemistry
wherein nia is 0 or 1 and Ria is a halogen atom, a nitro group, a cyano group, a hydroxy group, a carboxyl group, a linear or branched alkyl group having 1 to 6 carbon atoms, or a linear or branched alkoxy group having 1 to 5 carbon atoms.