Reversibly thermochromic composition, reversibly thermochromic microcapsule pigment encapsulating reversibly thermochromic composition, and writing instrument using reversibly thermochromic microcapsule pigment
A highly marketable reversibly thermochromic composition that provides a black color during color development by using a fluoran derivative having a specific structure as an electron-donating color-developing organic compound, turns colorless during decoloration, and is excellent in contrast between a colored state and a decolored state and a microcapsule pigment encapsulating the same. A reversibly thermochromic composition including: (a) a fluoran derivative having a specific structure 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, and a reversibly thermochromic microcapsule pigment encapsulating the same.
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
wherein na is 0, 1, or 2, each Y a is independently a halogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, Z a is a halogen atom provided that the substitution position of Z a is a para position, and each X a 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 Y a is independently a halogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms, Z a 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 Z a is a para position, one of the X a s is a linear or branched alkyl group having 1 to 8 carbon atoms, and the other of the X a s is the group represented by the formula (ia), wherein the formula (ia) is represented by
wherein nia is 0 or 1 and R ia 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.
2 . The reversibly thermochromic composition according to claim 1 , which is the composition of heat-decoloring type having a reversibly thermochromic function of exhibiting a decolored state in a temperature range not lower than a complete decoloring temperature and exhibiting a colored state in a temperature range not higher than a complete coloring temperature.
3 . A reversibly thermochromic microcapsule pigment encapsulating the reversibly thermochromic composition according to claim 1 .
4 . A reversibly thermochromic liquid composition comprising the reversibly thermochromic microcapsule pigment according to claim 3 and a vehicle.
5 . The reversibly thermochromic liquid composition according to claim 4 , which is selected from the group consisting of a printing ink, an ink for writing instruments, an ink for coating tools, an ink for a stamp, an ink for ink jet use, a paint, an ultraviolet curable ink, a painting color, a cosmetic, and a coloring liquid for fibers.
6 . A reversibly thermochromic solid molded article for coating comprising the reversibly thermochromic microcapsule pigment according to claim 3 and an excipient.
7 . The reversibly thermochromic solid molded article for coating according to claim 6 , which is a solid writing material or a solid cosmetic material.
8 . A resin composition for forming a reversibly thermochromic molded article comprising the reversibly thermochromic microcapsule pigment according to claim 3 and a molding resin.
9 . A reversibly thermochromic molded article obtained by molding the resin composition for forming a reversibly thermochromic molded article according to claim 8 .
10 . A reversibly thermochromic laminate comprising:
a support; and
a reversibly thermochromic layer comprising the reversibly thermochromic microcapsule pigment according to claim 9 .
11 . A writing instrument obtained by storing the ink for writing instruments according to claim 5 in an ink-storing tube of the writing instrument.
12 . The writing instrument according to claim 11 , which is a ballpoint pen.
13 . The writing instrument according to claim 12 , wherein a ball provided at a writing front-end of the ballpoint pen has a diameter of 0.3 to 0.5 mm.
14 . The writing instrument according to claim 12 , wherein a ball provided at a writing front-end of the ballpoint pen has a diameter of 0.5 to 1.0 mm.
15 . The writing instrument according to claim 11 , which is a marking pen.
16 . The writing instrument according to claim 11 , comprising a friction member that changes color of a handwriting of the writing instrument by frictional heat.