Thermochromic micro particles and thermochromic ink composition, writing apparatus and smart window using the same
The present invention relates to thermochromic micro particles capable of stably implementing a high chromogenic property and a decolorization property and having an improved erasing property, thermal resistance, and chemical resistance, and a thermochromic ink composition, a writing apparatus, and a smart window using the same. The thermochromic micro particles comprise a core part including a phase change material, a dye, and a developer, the phase change material including at least one selected from the group consisting of at least one chain hydrocarbon having a carbon number of 8 or more, a hydrated inorganic salt, alcohol having a carbon number of 3 or more, and polyalkyleneglycol; and a shell layer including a polymer resin.
1. Thermochromic micro particles comprising:
a core part including a phase change material, a dye, and a developer, the phase change material including at least one selected from the group consisting of at least one chain hydrocarbon having a carbon number of 8 or more, a hydrated inorganic salt, alcohol having a carbon number of 3 or more, and polyalkyleneglycol; and
a shell layer including a polymer resin;
wherein the developer includes 2,2-bis(4′-hydroxyphenyl) hexafluoropropane or 2,2-bis(4′-hydroxyphenyl) propane; and
wherein a weight ratio of the developer to the dye is 2 to 5.
2. The thermochromic micro particles of claim 1 , wherein:
a color-change temperature range defined by General Formula 1 below is 50° C. or more:
Color-change temperature range (Δ T )=an absolute value of a difference between a melting point of the phase change material and a crystallization temperature of the phase change material [General Formula 1].
3. The thermochromic micro particles of claim 2 , wherein:
the crystallization temperature of the phase change material is −20° C. to 0° C.
4. The thermochromic micro particles of claim 2 , wherein:
the melting point of the phase change material is 50° C. or more.
5. The thermochromic micro particles of claim 1 , wherein:
the chain hydrocarbon having a carbon number of 8 or more includes a straight chain saturated hydrocarbon having a carbon number of 10 to 50.
6. The thermochromic micro particles of claim 1 , wherein:
the hydrated inorganic salt includes a hydrate of an inorganic acid metal salt or a hydrate of an organic acid metal salt.
7. The thermochromic micro particles of claim 6 , wherein:
the inorganic acid metal salt includes sulfates, nitrates, carbonates, phosphates, thiosulfates, or halides of metals.
8. The thermochromic micro particles of claim 6 , wherein:
the organic acid metal salt includes acetates of metals.
9. The thermochromic micro particles of claim 1 , wherein:
the alcohol having a carbon number of 3 or more includes aliphatic alcohols having a carbon number of 6 to 50 or aromatic alcohols having a carbon number of 3 to 20.
10. The thermochromic micro particles of claim 1 , wherein:
a content of the phase change material on the basis of a weight of the thermochromic micro particles is 10 wt % to 70 wt %.
11. The thermochromic micro particles of claim 1 , wherein:
the dye is a lactone-based dye.
12. The thermochromic micro particles of claim 11 , wherein:
the lactone-based dye includes a phthalide-based compound or a fluoran-based compound.
13. The thermochromic micro particles of claim 1 , wherein:
a diameter of the thermochromic micro particle is 0.1 μm to 10 μm.
14. The thermochromic micro particles of claim 1 , wherein:
the core part or the shell layer included in the thermochromic micro particles further includes an expansion agent or a contraction agent.
15. A thermochromic ink composition comprising the thermochromic micro particles of claim 1 .
16. A writing apparatus comprising
an ink storage container filled with the thermochromic ink composition of claim 15 .
17. The writing apparatus of claim 16 , further comprising:
a friction body.
18. A window comprising a coating layer in which the thermochromic micro particles of claim 1 are dispersed.