Reversibly thermochromic composition and reversibly thermochromic microcapsule pigment encapsulating the same

1. A reversibly thermochromic composition comprising:

(a) a pyridine derivative represented by the following formula (A), 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,

each R A1 is independently hydrogen, a halogen group, or a linear or branched alkoxy group having 1 to 6 carbon atoms, provided that at least one of R A1 is an alkoxy group,

each mA is independently an integer of 1 to 3,

lA is an integer of 1 or 2, and

X is hydrogen or a group represented by the following formula:

wherein, each R A2 is independently hydrogen, a linear or branched alkyl group having 1 to 6 carbon atoms, or a linear or branched alkoxy group having 1 to 6 carbon atoms, and

each nA is independently an integer of 1 to 3,

provided that two X never simultaneously form hydrogen and never simultaneously form a phenyl group).

2. The composition according to claim 1 , wherein the component (a) is a pyridine derivative represented by the following formula (1) or (2):

(wherein

R 11 is a linear or branched alkyl group having 1 to 6 carbon atoms, or a linear or branched alkoxy group having 1 to 6 carbon atoms,

R 12 is hydrogen, a linear or branched alkyl group having 1 to 6 carbon atoms, or a linear or branched alkoxy group having 1 to 6 carbon atoms,

each R 13 is independently a halogen group or a linear or branched alkoxy group having 1 to 6 carbon atoms, provided that at least one of R 13 is an alkoxy group,

each R 14 is independently hydrogen, a halogen group, or a linear or branched alkoxy group having 1 to 6 carbon atoms,

l1 is an integer of 1 or 2, and

m1 and n1 each independently represents an integer of 1 to 3),

(wherein

each R 21 is independently a linear or branched alkyl group having 1 to 6 carbon atoms, or a linear or branched alkoxy group having 1 to 6 carbon atoms,

each R 22 is independently a halogen group or a linear or branched alkoxy group having 1 to 6 carbon atoms, provided that at least one of R 22 is an alkoxy group,

each R 23 is independently hydrogen, a halogen group, or a linear or branched alkoxy group having 1 to 6 carbon atoms,

l2 is an integer of 0 to 3, and

m2 and n2 represent an integer of 1 to 3).

3. The composition according to claim 2 , wherein in the pyridine derivative represented by the formula (1),

R 11 is a linear or branched alkyl group having 1 to 6 carbon atoms,

R 12 is hydrogen or a linear or branched alkyl group having 1 to 6 carbon atoms,

each R 13 is independently a halogen group or a linear or branched alkoxy group having 1 to 6 carbon atoms, provided that at least one of R 13 is an alkoxy group, and

l1 is 1.

4. The composition according to claim 2 , wherein in the pyridine derivative represented by the formula (1),

R 11 is a linear or branched alkyl group having 1 to 4 carbon atoms,

R 12 is hydrogen, or a linear or branched alkyl group having 1 to 4 carbon atoms,

each R 13 is independently a halogen group or a linear or branched alkoxy group having 1 to 4 carbon atoms, provided that at least one of R 13 is an alkoxy group,

R 14 is hydrogen, a halogen group, or a linear or branched alkoxy group having 1 to 4 carbon atoms,

l1 is 1, and

m1 and n1 are integers of 1 to 2.

5. The composition according to claim 2 , wherein in the pyridine derivative represented by the formula (2),

each R 21 is independently a linear or branched alkyl group having 1 to 6 carbon atoms, and

each R 22 is independently a halogen group or a linear or branched alkoxy group having 1 to 6 carbon atoms, provided that at least one of R 22 is an alkoxy group.

6. The composition according to claim 2 , wherein in the pyridine derivative represented by the formula (2),

each R 21 is independently a linear or branched alkyl group having 1 to 4 carbon atoms,

each R 22 is independently a halogen group or a linear or branched alkoxy group having 1 to 4 carbon atoms, provided that at least one of R 22 is an alkoxy group, and

each R 23 is independently hydrogen, a halogen group, or a linear or branched alkoxy group having 1 to 4 carbon atoms.

7. The composition according to claim 1 , wherein composition ratios of the component (b) and the component (c) with respect to 1 part of the component (a) are 0.1 to 100 parts and 5 to 200 parts, respectively, on mass basis.

8. A reversibly thermochromic microcapsule pigment encapsulating the reversibly thermochromic composition according to claim 1 .

9. A reversibly thermochromic liquid composition comprising the reversibly thermochromic microcapsule pigment according to claim 8 and a vehicle.

10. A resin composition for forming a reversibly thermochromic molded article comprising the reversibly thermochromic microcapsule pigment according to claim 8 , and a thermoplastic resin, a thermosetting resin, or wax.

11. A laminate comprising

a reversibly thermochromic layer comprising the reversibly thermochromic compositions according to claim 1 on a support.