Reversible thermochromic composition having improved light-fastness and product comprising same

Abstract

A reversible thermochromic composition which can be freely adjusted in its discoloration temperature even if the kind of electron donating compound and electron accepting compound to be used in combination remain the same and exhibits a remarkably improved light-fastness during quenching. A reversible thermochromic composition having an improved light-fastness comprising (a) an electron donating compound, (b) an electron accepting compound ultraviolet absorbing capacity represented by the following general formula I: 1

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a reversible thermochromic composition having an excellent discoloration sensitivity, which comprises a special electron accepting compound having ultraviolet absorbing capacity to exhibit an improved light-fastness, particularly during quenching, without impairing discoloration sensitivity and a product comprising same.

BACKGROUND ART

[0002] A thermochromic composition comprising an electron donating compound and an electron accepting compound in combination is known as disclosed in U.S. Pat. No. 3,560,229. Since the discoloration temperature of this composition is determined by the kind of the two compounds to be combined, it is very difficult to obtain a composition which can undergo discoloration at a desired temperature.

[0003] In order to solve this problem, the inventors proposed an invention which comprises using a specific alcohol, ester or ketone as a discoloration temperature adjustor to adjust the discoloration temperature to a desired value even when the kind of electron donating compound and electron accepting compound to be used in combination remain the same (U.S. Pat. No. 4,028,118, JP-B-6-59746 (The term “JP-B” as used herein means an “examined Japanese patent application”)).

[0004] The inventors further invented a process which comprises using a special light-fastness providing agent and light stabilizer having electron acceptingness to improve the light-fastness of a reversible thermochromic composition in quenched state (U.S. Pat. No. 5,879,438).

[0005] The above proposed invention can attain free adjustment of discoloration temperature even when the kind of electron donating compound and electron accepting compound to be used in combination remain the same and exerts an excellent effect of remarkably improving light-fastness in quenched state. However, as the added amount of the light stabilizer increases, the discoloration sensitivity tends to fall. Therefore, the above cited invention is limited in its practical use.

[0006] The present invention provides a reversible thermochromic composition which can be freely adjusted in its discoloration temperature even if the kind of electron donating compound and electron accepting compound to be used in combination remain the same and exhibits a remarkably improved light-fastness during quenching.

SUMMARY OF THE INVENTION

[0007] The present invention lies in the following constitutions:

[0008] 1. A reversible thermochromic composition having an improved light-fastness, which comprises

[0009] (a) an electron donating compound,

[0010] (b) an electron accepting compound having ultraviolet absorbing capacity which is represented by the following general formula I: 2

[0011] wherein X represents a hydrogen atom, —CnH2n+1 or —OCmH2m+1; m represents an integer of from 1 to 9; n represents an integer of from 1 to 10; and p represents an integer of from 1 to 3, and

[0012] (c) a discoloration temperature adjustor.

[0013] 2. A reversible thermochromic composition having an improved light-fastness, which comprises

[0014] (a) an electron donating compound,

[0015] (b) an electron accepting compound having ultraviolet absorbing capacity which is represented by the following general formula I: 3

[0016] wherein X represents a hydrogen atom, —CnH2n+1 or —OCmH2m+1; m represents an integer of from 1 to 9; n represents an integer of from 1 to 10; and p represents an integer of from 1 to 3,

[0017] (c) a discoloration temperature adjustor, and

[0018] (d) an electron accepting light-fastness providing agent represented by the following general formula II: 4

[0019] wherein n represents an integer of from 5 to 17 (straight-chain and branched); X represents a C1-C4 straight-chain or branched hydrocarbon or halogen; Y represents a C1-C4 straight-chain or branched hydrocarbon or halogen; p represents an integer of from 0 to 3; and m represents an integer of from 0 to 3.

[0020] 3. A reversible thermochromic composition having an improved light-fastness, which comprises

[0021] (a) an electron donating compound,

[0022] (b) an electron accepting compound having ultraviolet absorbing capacity represented by the following general formula I: 5

[0023] wherein X represents a hydrogen atom, —CnH2n+1 or —OCmH2m+1; m represents an integer of from 1 to 9; n represents an integer of from 1 to 10; and p represents an integer of from 1 to 3,

[0024] (c) a discoloration temperature adjustor,

[0025] (d) an electron accepting light-fastness providing agent represented by the following general formula II: 6

[0026] wherein n represents an integer of from 5 to 17 (straight-chain and branched) ; X represents a C1-C4 straight-chain or branched hydrocarbon or halogen; Y represents a C1-C4 straight-chain or branched hydrocarbon or halogen; p represents an integer of from 0 to 3; and m represents an integer of from 0 to 3, and

[0027] (e) a light stabilizer.

[0028] 4. The reversible thermochromic composition having an improved light-fastness according to any one of Clauses 1 to 3, which further comprises a microcapsule incorporating said reversible thermochromic composition therein.

[0029] 5. The reversible thermochromic composition having an improved light-fastness according to any one of Clauses 1 to 4, which further comprises a color developer blended in said reversible thermochromic composition having an improved light-fastness.

[0030] 6. The reversible thermochromic composition having an improved light-fastness according to Clause 5, wherein said color developer is a binder.

[0031] 7. A molding resin composition comprising a synthetic resin and a reversible thermochromic composition according to any one of Clauses 1 to 4 blended therein.

[0032] 8. A reversible thermochromic yarn comprising a reversible thermochromic composition according to any one of Clauses 1 to 4 and a thermoplastic resin.

[0033] 9. A reversible thermochromic layer having an improved light-fastness according to any one of Clauses 1 to 8, which further comprises

[0034] (f) a layer of light stabilizer and/or metallic luster pigment provided on the surface of a layer formed by a reversible thermochromic composition.

BRIEF DESCRIPTION OF THE DRAWINGS

[0035] FIG. 1 is a graph illustrating hysteresis characteristics on color density-temperature curve of a reversible thermochromic composition according to the invention.

[0036] FIG. 2 is a graph illustrating hysteresis characteristics on color density-temperature curve of a conventional reversible thermochromic composition.

[0037] The reference numerals in the figures have the following meanings.

T1 Full color development temperature
T2 Color development starting temperature
T3 Quenching starting temperature
T4 Full quenching temperature

DETAILED DESCRIPTION OF THE INVENTION

[0038] The present invention lies in a reversible thermochromic composition having an improved light-fastness in quenched state comprising an electron donating compound (a), an electron accepting compound having ultraviolet absorbing capacity and a discoloration temperature adjustor (c) and thus is characterized by the use of an electron accepting compound having ultraviolet absorbing capacity that provides a remarkable improvement of light-fastness in quenched state without impairing discoloration sensitivity.

[0039] A representative example of the electron donating compound is a leuco dye. However, since a leuco dye exhibits a poor light-fastness, a composition comprising such a dye ages when irradiated with light and shows deteriorated discolorability.

[0040] With reference to leuco dye, when provided with electron, i.e., placed in color-developed state, an electron donating compound can be greatly affected by visible light or indirect light to show deteriorated light-fastness and hence deteriorated discolorability.

[0041] On the other hand, when placed in quenched state, i.e., being not ionized, the electron donating compound is in the form of colorless molecular state and thus is greatly affected by ultraviolet rays to show a remarkably deteriorated discolorability. The thermochromic composition undergoes color development and quenching to perform display. Accordingly, light-fastness in quenched state, too, is important.

[0042] The color-developed state and quenched state of the thermochromic composition will be described hereinafter.

[0043] All the electron donating compound, the electron accepting compound and the discoloration temperature adjustor constituting the thermochromic composition are molecular compounds which are not ionized when actually handled. When the ambient temperature is not higher than the discoloration temperature, a reversible thermochromic composition having these components uniformly mixed with each other causes the electron donating compound and the electron accepting compound to be ionized and bonded to each other, making color development.

[0044] It is thought that in transient period during discoloration, the electron donating compound and the electron accepting compound are placed in between ionized state and molecular state and in somewhat ionized state, i.e., bonded to each other slightly ionically. Even when slightly ionized, color development occurs. Thus, some problem with light-fastness in color-developed state arises. Accordingly, transient state is considered color-developed state in respect to light-fastness.

[0045] On the contrary, when the ambient temperature is not lower than the discoloration temperature, the ionical bonding of the electron donating compound to the electron accepting compound disappears. These compounds then become molecular to cause quenching.

[0046] Accordingly, the blocking of ultraviolet rays by the addition of a light stabilizer to a reversible thermochromic composition the electron donating compound and electron accepting compound of which are molecular to develop quenched state is an exceptionally useful method for improving light-fastness in quenched state. However, as the added amount of the light stabilizer increases, the discoloration sensitivity decreases, making it more difficult to show sharp discoloration. Therefore, this method can be hardly effected on a practical basis depending on the purpose.

[0047] The electron accepting compound having ultraviolet absorbing capacity represented by the general formula I to be used in the invention has electron attraction properties itself. 7

[0048] wherein X represents a hydrogen atom, —CnH2n+1 or —OCmH2m+1; m represents an integer of from 1 to 9; n represents an integer of from 1 to 10; and p represents an integer of from 1 to 3.

[0049] In addition to action of receiving an electron donating compound and electron, the foregoing electron accepting compound having ultraviolet absorbing capacity exerts a special effect. In other words, the foregoing electron accepting compound having ultraviolet absorbing capacity absorbs ultraviolet rays, which have the greatest effect on light-fastness in quenched state, to become excited and then undergoes stable non-radiation deactivation from excited state to release energy and return to the ground state. This process of absorbing ultraviolet rays and releasing energy is repeated. At the same time, since this electron donating compound has a high acidity due to the electron accepting properties of the ultraviolet absorbing group, it undergoes excellent reaction of providing and receiving electron, making it possible to provide a reversible thermochromic composition which attains both improved light-fastness in quenched state and excellent discoloration sensitivity which could not be attained by the conventional process involving the addition of a light stabilizer.

[0050] In the electron accepting compound having ultraviolet absorbing capacity represented by the general formula I, n is an integer of from 1 to 10, and m is an integer of from 1 to 9. When n is greater than 10 or m is greater than 9, the resulting electron accepting compound exhibits too great a solubility in the component (c) and thus tends to have a discoloration sensitivity drop, making it difficult to provide a reversible thermochromic composition which attains both improved light-fastness in quenched state and excellent discoloration sensitivity.

[0051] As the electron accepting compound there may be used the electron accepting compound having ultraviolet absorbing capacity (b) alone. However, other electron accepting compounds may be used as well.

[0052] In the case where the electron accepting compound having ultraviolet absorbing capacity is used in combination with other electron accepting compounds, the amount of the electron accepting compound having ultraviolet absorbing capacity to be used is not smaller than 5% by weight, preferably not smaller than 10%, of the total amount of electron accepting compounds used.

[0053] When the proportion of the electron accepting compound having ultraviolet absorbing capacity is not greater than 5% by weight, the electron accepting compound having ultraviolet absorbing capacity cannot exert the foregoing special effect.

[0054] As other electron accepting compounds to be used in combination with the electron accepting compound having ultraviolet absorbing capacity, there are preferably used electron accepting light-fastness providing agents.

[0055] The electron accepting light-fastness providing agent (d) represented by the general formula II to be used in the invention is a bisphenol compound or bis(hydroxyphenyl) compound containing an alkyl group and two phenyl rings each having a hydroxyl group, which is represented by the following general formula II: 8

[0056] wherein n represents an integer of from 5 to 17 (straight-chain and branched) ; X represents a C1-C4 straight-chain or branched hydrocarbon or halogen; Y represents a C1-C4 straight-chain or branched hydrocarbon or halogen; p represents an integer of from 0 to 3; and m represents an integer of from 0 to 3. The alkyl moiety in the foregoing compound has from 5 to 17 carbon atoms. When the number of carbon atoms in the alkyl moiety falls below 5, the resulting light-fastness providing agent has a short alkyl moiety and hence an insufficient solubility in the discoloration temperature adjustor (c) that makes it impossible to provide a sufficient stable structure in a solid atmosphere at a temperature of not higher than the discoloration temperature. On the contrary, when the number of carbon atoms in the alkyl moiety exceeds 17, the resulting light-fastness providing agent has too long an alkyl moiety and hence too great a solubility in the discoloration temperature adjustor that weakens the color assuming power and deteriorates the discoloration sensitivity to disadvantage from the practical standpoint of view.

[0057] Most preferably, the alkyl group is a straight-chain alkyl group. The branches, if any, are preferably short.

[0058] The phenyl ring may have substituents such as straight-chain or branched alkyl group and halogen. In this case, the resulting light-fastness remains almost the same so far as the alkyl group to which the phenyl group is attached is as defined above.

[0059] Examples of other electron accepting compounds which can be used in combination with the electron accepting compound having ultraviolet absorbing capacity (b) include compounds having active proton, pseudo-acidic compounds (compounds which are not acids but act as an acid in the composition to allow the color development of the compound (a)), and compounds having electron holes.

[0060] Compounds having a phenolic hydroxyl group can exhibit the most effective thermochromic characteristics. However, there may be used compounds selected from the group consisting of aromatic carboxylic acids, C2-C5 aliphatic carboxylic acids, metal salt of carboxylic acids, acidic phosphoric acid esters, metal salt thereof, 1,2,3-triazole, derivatives thereof, thiourea, derivatives thereof, urea, derivatives thereof, guanidine, derivatives thereof, aromatic carboxylic anhydride, aliphatic carboxylic anhydride, boric acid esters, halogenated alcohol, oxazole, thiazole, imidazole, pyrazole, pyrrole, aromatic sulfonamides, and aromatic sulfonimides.

[0061] The reversible thermochromic composition comprising an electron donating compound (a), an electron accepting compound having ultraviolet absorbing capacity (b) and a discoloration temperature adjustor (c) of the invention absorbs ultraviolet rays, which have the greatest effect on light-fastness when the electron accepting compound having ultraviolet absorbing capacity (b) is in quenched state, and undergoes non-radiation deactivation to release energy, making it possible to provide better light-fastness in quenched state than the conventional reversible thermochromic composition. The further incorporation of a light-fastness providing agent (d) causes the electron donating compound (a) to have a weak interaction with the electron accepting compound having ultraviolet absorbing capacity (b) and the light-fastness providing agent (d) and become stabilized while being dissolved in the discoloration temperature adjustor (c) in quenched state, making it possible to inhibit photo-oxidation or photodecomposition caused by light and hence further improve light-fastness in quenched state.

[0062] Referring to light-fastness in color-developed state by the light-fastness providing agent, the ionized state of the electron donating compound and the light-fastness providing agent having a long-chain alkyl group (d) can be stabilized to give a strong interaction, making it possible to improve light-fastness in quenched state in the discoloration temperature adjustor (c), which has a strong aliphatic atmosphere.

[0063] Further, the presence of a light stabilizer (e) in the reversible thermochromic composition comprising the components (a), (b), (c) and (d) gives an enhanced stabilizing effect that makes it possible to further improve light-fastness in quenched state.

[0064] The present invention also relates to a reversible thermochromic layer having a remarkably improved light-fastness in quenched state obtained by providing a layer of light stabilizer or metallic luster pigment (f) on the surface of the layer formed by the thermochromic composition of the invention. This thermochromic layer is very excellent also in discoloration sensitivity. In color-developed state, too, the light stabilizer layer or metallic lust pigment layer blocks ultraviolet rays or visible light to improve light-fastness.

[0065] The reversible thermochromic composition of the invention comprises an electron donating compound (a), an electron accepting compound having ultraviolet absorbing capacity (b), and a discoloration temperature adjustor (c). As previously mentioned, the reversible thermochromic composition of the invention may further comprise an electron accepting light-fastness providing agent (d) and a light stabilizer (e) singly or in combination. The reversible thermochromic composition of the invention may further comprise other electron accepting compounds.

[0066] The use of the electron accepting compound having ultraviolet absorbing capacity (b) makes it possible to improve discoloration sensitivity. The academic analysis of this mechanism is not necessarily sufficiently made. Judging from the repeatable and reproducible results, the inventor thinks that the special electron accepting group in the electron accepting compound having ultraviolet absorbing capacity (b) causes the acidity to rise and hence improves discoloration sensitivity.

[0067] Compounds employable in the invention will be exemplified below.

[0068] As the electron donating compound which acts as the component (a) there may be used any of those listed in Tables 1 and 2 below.

TABLE 1
Compound group                Name of compound
Diphenylmethane phthalides    3,3-Bis(p-dimethylaminophenyl)-6-dimethylaminophthalide
                              3,3-Bis(p-dimethylaminophenyl)phthalide, etc.
Phenylindolyl phthalides      3-(4-Diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-
                              yl)phthalide
                              3-(2-Methyl-4-diethylamino)phenyl-3-[1-(2-methoxyethyl)-2-
                              methylindol-3-yl]phthalide, etc.
Indolyl phtahlides            3,3-Bis(1-n-butyl-2-methylindol-3-yl)phthalide
                              3,3-Bis(1-ethyl-2-methylindol-3-yl)phthalide
                              3,3-Bis(1-n-pentyl-2-methylindol-3-yl)phthalide
                              3-(1-n-butyl-2-methyl-indol-3-yl)-3-(1-n-octyl-2-methyl-indol-
                              3-yl)phthalide, etc.
Diphenylmethane azaphthalides 3,3-Bis(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide, etc.
Phenylindolyl azaphthalizes   3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-
                              yl)-4-azaphthalide
                              3-(4-diethylamino-2-methylphenyl)-3-(1-ethyl-2-methylindol-
                              3-yl)-4-azaphthalide
                              3-[2-ethoxy-4-(N-ethylanilino)phenyl]-3-(1-ethyl-2-
                              methylindol-3-yl)-4-azaphthalide
                              3-[2-ethoxy-4-(N-ethyl-N-4-n-butylphenylamino)phenyl]-3-(1-
                              ethyl-2-methylindol-3-yl)-7-azaphthalide, etc.
Fluoraones                    3,6-Dimethoxyfluorane
                              3,6-Di-n-butoxyfluorane
                              2-Chloro-6-diethylaminofluorane
                              2-Methyl-6-diethylaminofluorane
                              2-Methyl-6-(N-ethyl-N-p-tolylamino)fluorane
                              3-Chloro-6-cyclohexylaminofluorane
                              2-Methyl-6-cyclohexylaminofluorane
                              2-Anilino-6-(N-ethyl-N-n-hexylamino)fluorane
                              2-(2-Chloroanilino)-6-dimethylaminofluorane
                              2-(2-Chloroanilino)-6-di-n-butylaminofluorane
                              2-(3-Trifluoromethylanilino)-6-diethylaminofluorane
                              2(N-cyclohexyl-N-benzylamino)-6-diethylaminofluorane
                              2-N,N-dibenzylamino-6-diethylaminofluorane
                              2-(N-methylanilino)-6-(N-ethyl-N-p-tolylamino)fluorane
                              1,3-Dimethyl-6-diethylaminofluorane
                              2-Chloro-3-methyl-6-diethylaminofluorane
                              2-Chloro-3-methyl-6-(4-di-n-butylaminoanilino)fluorane
                              2-n-Octylamino-3-methyl-6-diethylaminofluorane
                              2-N,N-dibenzylamino-3-methyl-6-diethylaminofluorane
                              2-N,N-dibenzylamino-4-methyl-6-diethylaminofluorane
                              2-Anilino-3-methyl-6-(N-methyl-N-n-propylamino)fluorane
                              2-Anilino-3-methyl-6-diethylaminofluorane
                              2-Anilino-3-methyl-6-(N-ethyl-N-isobutylamino)fluorane
                              2-Anilino-3-methyl-6-di-n-butylaminofluorane
                              2-Anilino-3-methyl-6-(N-ethyl-N-isopentylamino)fluorane
                              2-Anilino-3-methyl-6-di-n-pentylaminofluorane
                              2-Anilino-3-methyl-6-(N-methyl-N-cyclohexylamino)fluorane
                              2-Anilino-3-methyl-6-(N-ethyl-N-p-tolylamino)fluorane

[0069]

TABLE 2
Compound group        Name of compound
Fluoranes (continued  2-(2-fluoroanilino)-6-di-n-butylaminofluorane
from above)           2-Xylidino-3-methyl-6-diethylaminofluorane
                      2-(p-n-Butylanilino)-3-methyl-6-diethylaminofluorane
                      1,2-Benz-6-diethylaminofluorane
                      1,2-Benz-6-(N-ethyl-N-isobutylamino)fluorane
                      1,2-Benz-6-(N-ethyl-N-isoamylamino)fluorane
                      1,2-Benz-6-di-n-butylaminofluorane, etc.
Styrylguinolines      2-(3-Methoxy-4-dodecoxystyryl)guinoline, etc.
Pyridines             4-(4-N-methyl-N-benzylaminophenyl)pyridine
                      2,6-Diphenyl-4-(4-dimethylaminophenyl)pyridine
                      2,6-Bis(4-methoxyphenyl)-4-(4-dimethylaminophenyl)pyridine
                      2,6-Dimethyl-3,5-biscarboethoxy-4-(4-dimethylaminophenyl)pyridine
                      2-(2-octoxyphenyl)-4-(4-dimethylaminophenyl)-6-phenylpyridine
                      2,6-Diethoxy-4-(4-diethylaminophenyl)pyridine
                      2,6-Bis(4-n-butoxyphenyl)-4-(4-dimethylaminophenyl)pyridine
                      2,6-Bis(2-n-butoxyphenyl)-4-(4-dimethylaminophenyl)pyridine
                      2,6-Bis(2-ethoxyphenyl)-4-(4-dimethylaminophenyl)pyridine
                      2,6-Bis(2-ethoxyphenyl)-4-(4-diethylaminophenyl)pyridine, etc.
Quinazolines          2-(4-Dimethylaminophenyl)-4-methoxyquinazoline
                      2-(4-Dimethylaminophenyl)-4-phenoxyquinazoline
                      2-(4-Dimethylaminophenyl)-4-(4-nitrophenyloxy)quinazoline
                      2-(4-N-methylanilinophenyl)-4-phenoxyquinazoline
                      2-(4-Piperidinophenyl)-4-phenoxyquinazoline
                      2-(4-Dimethylaminophenyl)-4-(4-chlorophenyloxy)quinazoline
                      2-(4-Dimethylaminophenyl)-4-(4-methoxyphenyloxy)guinazoline, etc.
Bisquinazolines       4,4’-(Ethylenedioxy)-bis[2-(4-diethylaminophenyl)quinazoline]
                      4,4’-[Propylenedioxy(1,3)]-bis[2-(4-diethylaminophenyl)quinazoline
                      4,4’-[Butylenedioxy(1,3)]-bis[2-(4-diethylaminophenyl)quinazoline
                      4,4’-[Butylenedioxy(1,4)]-bis[2-(4-diethylaminophenyl)quinazoline
                      4,4’-(Oxydiethylenedioxy)-bis[2-(4-diethylaminophenyl)quinazoline
                      4,4’-(Ethylenedioxy)-bis[2-(4-piperidinophenyl)quinazoline
                      4,4’-(Ethylenedioxy)-bis[2-(4-di-n-propylaminophenyl)quinazoline
                      4,4’-(Ethylenedioxy)-bis[2-(4-di-n-butylaminophenyl)quinazoline
                      4,4’-(Cyclohexylenedioxy)-bis[2-(4-diethylaminophenyl)guinazoline, etc.
Ethylenophthalides    3,3-Bis[1,1-bis-(p-dimethylaminophenyl)ethyleno-2]phthalide
                      3,3-Bis[1,1-bis-(2-methyl-4-dimethylaminophenyl)ethyleno-2]phthalide
                      3,3-Bis[1,1-bis-(p-dimethylaminophenyl)ethyleno-2]-4,5,6,7-
                      tetrachlorophthalide, etc.
Ethylenoazaphthalides 3,3-Bis[1,1-bis-(p-dimethylaminophenyl)ethyleno-2]-4-azaphthalide
                      3,3-Bis[1,1-bis-(p-dimethylaminophenyl)ethyleno-2]-4,7-diazaphthalide
                      3-(p-Dimethylaminophenyl)-3-[1,1-bis-(p-
                      dimethylaminophenyl)ethyleno-2]-4-azaphthalide, etc.
Fluorenes             3,6-Bis(dimethylamino)fluorenespiro(3,3’)-6’-dimethylaminophthalide
                      3,6-Bis(diethylamino)fluorenespiro(3,3’)-4’-azaphthalide
                      3,6-Bis(diethylamino)fluorenespiro(3,3’)-7’-azaphthalide
                      3,6-Bis(diethylamino)fluorenespiro(3,3’)-4’,7’-diazaphthalide, etc.

[0070] As the electron accepting compound having ultraviolet absorbing capacity which acts as the component (b) there may be preferably used any of those listed in Table 3 below.

TABLE 3
Compound group	Name of compound
Unsubstituted type	2,4-Dihydroxybenzophenone
Alkyl-	Mono-	2,4-Dihydroxy-2’-methylbenzophenone
sub-	substituted	2,4-Dihydroxy-3’-methylbenzophenone
stituted		2,4-Dihydroxy-4’-methylbenzophenone
type		2,4-Dihydroxy-4’-ethylbenzophenone
		2,4-Dihydroxy-4’-n-propylbenzophenone
		2,4-Dihydroxy-4’-isopropylbenzophenone
		2,4-Dihydroxy-4’-n-butylbenzophenone
		2,4-Dihydroxy-4’-isobutylbenzophenone
		2,4-Dihydroxy-4’-tert-butylbenzophenone
		2,4-Dihydroxy-4’-n-pentylbenzophenone
		2,4-Dihydroxy-4’-n-hexylbenzophenone
		2,4-Dihydroxy-4’-n-heptylbenzophenone
		2,4-Dihydroxy-4’-n-octylbenzophenone
		2,4-Dihydroxy-4’-n-decylbenzophenone, etc.
	Di-	2,4-Dihydroxy-2’,3’-dimethylbenzophenone
	substituted	2,4-Dihydroxy-2’,4’-dimethylbenzophenone
		2,4-Dihydroxy-2’,5’-dimethylbenzophenone
		2,4-Dihydroxy-2’,6’-dimethylbenzophenone
		2,4-Dihydroxy-3’,4’-dimethylbenzophenone
		2,4-Dihydroxy-3’,5’-dimethylbenzophenone, etc.
	Tri-	2,4-Dihydroxy-2’,4’,6’-trimethylbenzophenone, etc.
	substituted
Alkoxy-	Mono-	2,4-Dihydroxy-2’-methoxybenzophenone
sub-	substituted	2,4-Dihydroxy-3’-methoxybenzophenone
stituted		2,4-Dihydroxy-4’-methoxybenzophenone
type		2,4-Dihydroxy-2’-ethoxybenzophenone
		2,4-Dihydroxy-4’-ethoxybenzophenone
		2,4-Dihydroxy-4’-n-propoxybenzophenone
		2,4-Dihydroxy-4’-isopropoxybenzophenone
		2,4-Dihydroxy-4’-isobutylbenzophenone
		2,4-Dihydroxy-4’-n-butoxybenzophenone
		2,4-Dihydroxy-4’-n-pentyloxybenzophenone
		2,4-Dihydroxy-4’-n-hexyloxybenzophenone
		2,4-Dihydroxy-4’-n-heptyloxybenzophenone
		2,4-Dihydroxy-4’-n-octyloxybenzophenone
		2,4-Dihydroxy-4’-n-nonyloxybenzophenone, etc.
	Di-	2,4-Dihydroxy-2’,3’-dimethoxybenzophenone
	substituted	2,4-Dihydroxy-2’,4’-dimethoxybenzophenone
		2,4-Dihydroxy-2’,5’-dimethoxybenzophenone
		2,4-Dihydroxy-2’,6’-dimethoxybenzophenone
		2,4-Dihydroxy-3’,4’-dimethoxybenzophenone
		2,4-Dihydroxy-3’,5’-dimethoxybenzophenone
		2,4-Dihydroxy-3’,4’-dimethoxybenzophenone, etc.
	Tn-	2,4-Dihydroxy-2’,3’,4’-trimethoxybenzophenone
	substituted	2,4-Dihydroxy-2’,3’,6’-trimethoxybenzophenone
		2,4-Dihydroxy-3’,4’,5’-trimethoxybenzophenone
		2,4-Dihydroxy-3’,4’,5’-triethoxybenzophenone, etc.

[0071] As the discoloration temperature adjustor which acts as the component (c) there is preferably used any of those listed in Tables 4 to 10.

TABLE 4
Compound group                 Name of compound
(Alcohols)                     Decyl alcohol
Monovalent aliphatic saturated Undecyl alcohol
alcohol having 10 or more      Dodecyl alcohol
carbon atoms                   Tridecyl alcohol
                               Tetradecyl alcohol
                               Pentadecyl alcohol
                               Hexadecyl alcohol
                               Heptadecyl alcohol
                               Octadecyl alcohol
                               Eicodecyl alcohol
                               Docosyl alcohol, etc.
(Ester-1)                      Ethyl caprylate
Esters having 10 or more       Octyl caprylate
carbon atoms are effective.    Stearyl caprylate
Examples of these esters       Myristyl caprate
include esters obtained by     Docosyl caprate
arbitrary combination of       Cetyl caprate
monovalent carboxylic acid     Stearyl caprate
having aliphatic and alicyclic 2-Ethylhexyl laurate
or aromatic ring and           n-Decyl laurate
monovalent alcohol having      3-Methylbutyl myristate
aliphatic and alicyclic or     Cetyl myristate
aromatic ring, esters obtained Stearyl myristate
by arbitrary combination of    Isopropyl palmitate
polyvalent carboxylic acid     Neopentyl palmitate
having aliphatic and alicyclic Nonyl palmitate
or aromatic ring and           Stearyl palmitate
monovalent alcohol having      Cyclohexyl palmitate
aliphatic and alicyclic or     n-Butyl stearate
aromatic ring, and esters      2-Methylbutyl stearate
obtained by arbitrary          3,5,5-Trimethylhexyl stearate
combination of monovalent      n-Undecyl stearate
carboxylic acid having         Pentadecyl stearate
aliphatic and alicyclic or     Stearyl stearate
aromatic ring and polyvalent   Cyclohexylmethyl stearate
alcohol having aliphatic and   Isopropyl behenate
alicyclic or aromatic ring.    Hexyl behenate
                               Lauryl behenate
                               Behenyl behenate
                               Cetyl benzoate
                               Stearyl p-tert-butylbenzoate
                               Dimyristyl phthalate
                               Distearyl phthalate
                               Dimyristyl oxalate
                               Dicetyl oxalate
                               Dicetyl malonate
                               Dilauryl succinate
                               Dilauryl glutarate
                               Diundecyl adipate
                               Dilauryl azelate
                               Di-(n-nonyl) sebacate

[0072]

TABLE 5
Compound group                   Name of compound
(Ester-1)                        Dineopentyl 1,18-octadecylmethylene-
                                 dicarboxylate
                                 Ethyleneglycol dimyristate
                                 Propyleneglycol dilaurate
                                 Propyleneglycol distearate
                                 Hexyleneglycol dipalmitate
                                 1,5-Pentanediol distearate
                                 1,2,6-Hexanetriol trimyristate
                                 1,4-Cyclohexanediol didecyl
                                 1,4-Cyclohexanedimethanol dimyristate
                                 Xylene glycol dicaprinate
                                 Xylene glycol distearate, etc.
(Ester-2)                        2-Ethylhexyl butyrate
Also effective are ester of      2-Methylbutyl caproate
saturated aliphatic acid with    1-Ethylpentyl caproate
branched aliphatic alcohol and   2-Methylpentyl caproate
ester of unsaturated aliphatic   2-Methylbutyl caprate
acid or saturated aliphatic acid 2-Methylpentyl caprate
which is branched or has         2-Methylbutyl caprate
substituents with aliphatic      2-Ethylhexyl caprate
alcohol which is branched or has 1-Methylpentyl caprate
16 or more carbon atoms.         2-Methylpentyl caprate
                                 1,1-Dimethylpropyl laurate
                                 2-Methylpentyl laurate
                                 1-Ethylhexyl laurate
                                 3,5,5-Trimethylhexyl laurate
                                 3,7-Dimethyloctyl laurate
                                 1-Ethylhexyl myristate
                                 2-Ethylhexyl myristate
                                 3,7-Dimethyloctyl myristate
                                 1-Ethylpropyl palmitate
                                 1-Ethylpentyl palmitate
                                 2-Methylhexyl palmitate
                                 1-Ethylhexyl palmitate
                                 3,5,5-trimethylhexyl palmitate
                                 3,7-Dimethyloctyl palmitate
                                 1-Methylpropyl stearate
                                 1-Ethylpropyl stearate
                                 2-Methylbutyl stearate
                                 3-Methylbutyl stearate
                                 Neopentyl stearate
                                 1-Methylhexyl stearate
                                 2-Methylhexyl stearate
                                 3,5,5-Trimethylhexyl stearate
                                 1-Methylheptyl stearate
                                 1-Methyloctyl stearate
                                 3,7-Dimethyloctyl stearate
                                 1-Ethylpropyl behenate
                                 2-Methylbutyl behenate
                                 3,7-Dimethyloctyl behenate
                                 1-Ethylpropyl behenate
                                 2-Methylbutyl behenate
                                 3-Methylbutyl behenate
                                 2-Methylhexyl behenate
                                 2-Ethylhexyl behenate
                                 1-Methylheptyl behenate
                                 3,7-Dimethyloctyl behenate

[0073]

TABLE 6
Compound group                   Name of compound
(Ester-2)                        Stearyl oleate
                                 Behenyl oleate
                                 Stearyl linoleate
                                 Behenyl linoleate
                                 3,7-Dimethyloctyl erucate
                                 Stearyl erucate
                                 Isostearyl erucate
                                 Cetyl isostearate
                                 Stearyl isostearate
                                 2-Metylpentyl 12-hydroxystearate
                                 2-Ethylhexyl 18-bromostearate
                                 Isostearyl 2-ketomyristate
                                 2-Ethylhexyl 2-fluoromyristate, etc.
(Ester-3)                        Cetyl butyrate
The use of esters having ΔT      Stearyl butyrate
value (melting point-cloudy      Behenyl butyrate
point) of not higher than 3° C.  2-Methylbutyl caproate
such as those disclosed in above 2-Methylpentyl caproate
cited JP-B-1-2398 among the      1-Ethylpentyl caproate
foregoing esters makes it        2-Methylbutyl caprylate
possible to exhibit              2-Methylpentyl caprylate
thermochromic characteristics    2-Methylbutyl caprate
having a small hysteresis (width: 1-Methylpentyl caprate
0.5 C. to 2.0° C.) on color density- 2-Methylpentyl caprate
temperature curve and a high     2-Ethylhexyl caprate
responce.                        1,1-Dimethylpropyl laurate
Examples of the esters having    2-Methylpentyl laurate
ΔT width of not greater than 3° C. 1-Ethylhexyl laurate
include alkylester, arylester,   3,5,5-Trimethylhexyl laurate
arylakylester, alicyclic alkylester 3,7-Dimethyloctyl laurate
and branched ester of aromatic   1-Ethylhexyl myristate
and aliphatic carboxylic acids,  2-Ethylhexyl myristate
and substituted derivatives      3,5,5-Trimethylhexyl myristate
thereof.                         3,7-Dimethyloctyl myristate
                                 n-Butyl palmitate
                                 1-Ethylpropyl palmitate
                                 1-Ethylpentyl palmitate
                                 1-Ethylhexyl palmitate
                                 3,5,5-Trimethylhexyl palmitate
                                 3,7-Dimethyloctyl palmitate
                                 1-Methylpropyl stearate
                                 1-Ethylpropyl stearate
                                 n-Butyl stearate
                                 3-Methylbutyl stearate
                                 n-Hexyl stearate
                                 1-Methylhexyl stearate
                                 2-Methylhexyl stearate
                                 1-Methylheptyl stearate
                                 1-Methyloctyl stearate
                                 3,7-Dimethyloctyl stearate
                                 Lauryl stearate
                                 n-Butyl arachate
                                 n-Butyl behenate
                                 1-Ethylpropyl behenate

[0074]

TABLE 7
Compound group                   Name of compound
(Ester-3)                        3-Methylbutyl behenate
                                 2-Methylhexyl behenate
                                 2-Ethylhexyl behenate
                                 1-Methylheptyl behenate
                                 3,7-Dimethyloctyl behenate
                                 n-Butyl erucate
                                 3,7-Dimethyloctyl erucate
                                 Isostearyl erucate
                                 Stearyl isostearate
                                 Cetyl isostearate
                                 2-Methylpentyl 12-hydroxystearate
                                 2-Ethylhexyl 18-bromostearate
                                 Isostearate 2-ketomyristate
                                 2-Ethylhexyl 2-fluoromyristate
                                 Stearyl oleate
                                 Behenyl oleate
                                 Stearyl linoleate
                                 Behenyl linoleate, stc.
(Ester-4)                        Compound group (1)
In order to provide a color memory Stearyl 2-methylbenzoate
thermochromism dependent on temperature Cetyl 4-tert-butylbenzoate
change, i.e., discoloration with a great Behenyl 4-cyclohexylbenzoate
hysteresis (shape of curve made by plotting Myristyl 4-phenylbenzoate
color density change with temperature change Lauryl 4-octylbenzoate
differs from change of temperature from low Hexyl 3,5-dimethylbenzoate
value to high value in discoloration Stearyl 3-ethylbenzoate
temperature range to reversed change; the two Decyl 4-isopropylbenzoate
curves make a loop) on color density- Stearyl 4-benzoylbenzoate
temperature curve, it is effective to use a Phenyl 4-tert-butylbenzoate
carboxylic acid ester compound showing ΔT 4-Chlorobenzyl 2-methylbenzoate
value (melting point-cloudy point) of not lower Stearyl 4-chlorobenzoate
than 5° C. to lower than 50° C. disclosed in JP-B- Myristyl 3-bromobenzoate
4-17154 proposed by the present applicant. Stearyl 2-chloro-4-bromobenzoate
Compound group (1)               Decyl 3,4-dichlorobenzoate
Carboxylic acid ester containing substituted Octyl 2,4-dibromobenzoate
aromatic group in molecule       Cetyl 3-nitrobenzoate
Compound group (2)               Cyclohexylmethyl 4-aminobenzoate
Ester of carboxylic acid having unsubstituted Cetyl 4-diethylaminobenzoate
aromatic ring and aromatic alcohol having 14 Stearyl 4-anilinobenzoate
or more carbon atoms             Decyl 4-methoxybenzoate
Compound group (3)               Cetyl 4-methoxybenzoate
Carboxylic acid ester containing cycloalkyl Octyl 4-butoxybenzoate
group in molecule                Cetyl 4-hydroxybenzoate
Compound group (4)               4-Methoxyphenylmethyl benzoate
Ester of aliphatic acid having 6 or more Stearyl p-chlorophenylacetate
carbon atoms with unsubstituted aromatic Cetyl p-chlorophenylacetate
alcohol or phenol                Benzyl salicylate
Compound group (5)               Neopentyl salicylate
Ester of aliphatic acid having 4 or more 4-Methoxymethylphenylmethyl salicylate
carbon atoms with polarized aliphatic alcohol 4-Chlorophenylmethyl benzoate
                                 4-Chlorophenylmethyl caprate
                                 4-Methoxyphenylmethyl myristate
                                 4-Methylphenylmethyl stearate
                                 4-Nitrophenylmethyl stearate

[0075]

TABLE 8
Compound group               Name of compound
(Ester-4; continued from     4-Methylphenylmethyl caproate
above)                       2-Chlorophenylmethyl myristate
Compound group (6)           4-Methoxyphenylmethyl caprate
Diester of dicarboxylic acid 4-Chloropophenyl 11-bromolaurate
with aromatic alcohol or     4-Isopropylphenyl stearate
polarized aliphatic alcohol  Compound group (2)
Compound group (7)           Stearyl 1-naphthoate
Other compounds              Cetyl benzilate
                             Stearyl benzilate
                             Decyl 3-benzoylpropionate
                             Stearyl benzoate
                             Cetyl benzoate
                             Myristyl benzoate
                             Compound group (3)
                             Cyclohexylmethyl cinnamate
                             Cyclohexyl laurate
                             Cyclohexyl myristate
                             Cyclohexyl palmitate
                             Cyclohexylmethyl stearate
                             Cyclohexylethyl stearate
                             Stearyl cyclohexylethylacetate
                             Stearyl 2-cyclohexylpropionate
                             Stearyl cyclohexanecarboxylate
                             Cyclohexyl 2-benzoylpropionate
                             Compound group (4)
                             Benzyl caproate
                             Benzyl palmitate
                             3-Phenylpropyl stearate
                             Phenyl 11-bromolaurate
                             Compound group (5)
                             Neopentyl octylate
                             Neopentyl laurate
                             Compound group (6)
                             Dibenzyl sebacate
                             Dineopentyl 4,4’-diphenylcarboxylate
                             Dibenzyl azodicarboxylate
                             Compound group (7)
                             Benzyl cinnamate
                             Heptyl stearate
                             Didecyl adipate
                             Dilauryl adipate
                             Dimyristyl adipate
                             Decetyl adipate
                             Distearyl adipate
                             Trilaurin
                             Trimyristin
                             Tristearin
                             Dimyristin
                             Distearin, etc.

[0076]

TABLE 9
Compound group                 Name of compound
(Ester-5)                      n-Pentadecyl acetate
Also effective are aliphatic   n-Tridecyl butyrate
acid ester compound obtained   n-Pentadecyl butyrate
from aliphatic monovalent      n-Undecyl caproate
alcohol having 9 or more odd   n-Tridecyl caproate
number of carbon atoms and     n-Pentadecyl caproate
aliphatic carboxylic acid      n-Nonyl caprylate
having even number of carbon   n-Undecyl caprylate
atoms and aliphatic acid ester n-Tridecyl caprylate
compound having from 17 to     n-Pentadecyl caprylate
23 carbon atoms obtained from  n-Heptyl caprylate
n-pentyl alcohol or n-heptyl   n-Nonyl caprylate
alcohol and aliphatic          n-Undecyl caprylate
carboxylic acid having from 10 n-Tridecyl caprylate
to 16 even number of carbon    n-Pentadecyl caprylate
atoms.                         n-Pentyl laurate
                               n-Heptyl laurate
                               n-Nonyl laurate
                               n-Undecyl laurate
                               n-Tridecyl laurate
                               n-Pentadecyl laurate
                               n-Pentyl myristate
                               n-Heptyl myristate
                               n-Nonyl myristate
                               n-Undecyl myristate
                               n-Tridecyl myristate
                               n-Pentadecyl myristate
                               n-pentyl palmitate
                               n-Heptyl palmitate
                               n-Nonyl palmitate
                               n-Undecyl palmitate
                               n-Tridecyl palmitate
                               n-Pentadecyl palmitate
                               n-Nonyl stearate
                               n-Undecyl stearate
                               n-Tridecyl stearate
                               n-Pentadecyl stearate
                               n-Nonyl eicosanate
                               n-Undecyl eicosanate
                               n-Tridecyl eicosanate
                               n-Pentadecyl eicosanate
                               n-Nonyl behenate
                               n-Undecyl behenate
                               n-Tridecyl behenate
                               n-Pentadecl behenate, etc.

[0077]

TABLE 10
Compound group    Name of compound
(Ketone-1)        2-Decanone, 3-Decanone, 4-Decanone, 2-Undecanone,
Aliphatic ketones 3-Undecanone, 4-Undecanone, 5-Undecanone,
having 10 or      2-Dodecanone, 3-Dodecanone, 4-Dodecanone,
more carbon       5-Dodecanone, 2-Tridecanone, 3-Tridecanone,
atoms             2-Tetradecanone, 2-Pentadecanone, 8-Pentadecanone,
                  2-Hexadecanone, 3-Hexadecanone, 9-Heptadecanone,
                  2-Pentadecanone, 2-Octadecanone, 2-Nonadecanone,
                  10-Nonadecanone, 2-Eicosanone, 11-Eicosanone,
                  2-Heneicosanone, 2-Docosanone, Lauron, Stearon, etc.
(Ketone-2)        n-Octadecanophenone, n-Heptadecanophenone, n-
Arylalkylketones  Hexadecanophenone, n-Pentadecanophenone, n-
having from 12 to Tetradecanophenone, 4-n-Dodecaacetophenone, n-
24 carbon atoms   Tridecanophenone, 4-n-Undecanoacetopheflofle, n-
                  Laurophenone, 4-n-Decanoacetophenone, n-
                  Undecanophenone, 4-n-Nonylacetophenone, n-
                  Decanophenone, 4-n-Octylacetophenone, n-
                  Nonanophenone, n-Octanophenone, 4-n-
                  Heptylacetophenone, 4-n-Hexylacetophenone, 4-
                  Cyclohexylacetophenone, 4-Tert-butylpropiophenone,
                  n-Heptaphenone, 4-n-Pentylacetophenone, Cyclohexyl
                  phenyl ketone, Benzyl-n-butyl ketone, 4-n-Butyl
                  acetophenone, n-Hexanophenone, 4-Isobutyl
                  acetophenone, 1-Acetonaphthone, 2-Acetonaphthone,
                  Cyclopentyl phenyl ketone, etc.
(Ethers)          Dipentyl ether, Dihexyl ether, Diheptyl ether, Dioctyl
Aliphatic ethers  ether, Dinonyl ether, Didecyl ether, Diundecyl ether,
having 10 or      Didodecyl ether, Ditridecyl ether, Ditetradecyl ether,
more carbon       Dipentadecyl ether, Dihexadecyl ether, Dioctadecyl
atoms             ether, Undecanediol dimethyl ether, Dodecanediol
                  dimethyl ether, Tridecanediol dimethyl ether,
                  Decanediol diethyl ether, Undecanediol diethyl ether,
                  etc.

[0078] As the electron accepting light-fastness providing agent which acts as the component (d) there is preferably used any of those listed in Tables 11 and 12.

TABLE 11
Compound
group         Name of compound
1. Compound   1,1-Bis(4-hydroxyphenyl)-n-hexane,
having        1,1-Bis(4-hydroxyphenyl)-2-ethylbutane,
aromatic ring 1,1-Bis(4-hydroxyphenyl)-2-methylpentane,
free of       1,1-Bis(4-hydroxyphenyl)-n-heptane,
substituents  1,1-Bis(4-hydroxyphenyl)-2,3-dimethylpentane,
              1,1-Bis(4-hydroxyphenyl)-n-octane,
              1,1-Bis(4-hydroxyphenyl)-2-ethylhexane,
              1,1-Bis(4-hydroxyphenyl)-n-nonane,
              1,1-Bis(4-hydroxyphenyl)-n-decane,
              1,1-Bis(4-hydroxyphenyl)-3,7-dimethyloctane,
              1,1-Bis(4-hydroxyphenyl)-n-undecane,
              1,1-Bis(4-hydroxyphenyl)-n-dodecane,
              1,1-Bis(4-hydroxyphenyl)-n-tridecane,
              1,1-Bis(4-hydroxyphenyl)-n-tetradecane,
              1,1-Bis(4-hydroxyphenyl)-n-pentadecane,
              1,1-Bis(4-hydroxyphenyl)-n-hexadecane,
              1,1-Bis(4-hydroxyphenyl)-n-heptadecane,
              1,1-Bis(4-hydroxyphenyl)-n-octadecane, etc.
2. Compound   1,1-Bis(3-methyl-4-hydroxyphenyl)-n-hexane,
having mono-  1,1-Bis(3-methyl-4-hydroxyphenyl)-2-ethylbutane,
substituted   1,1-Bis(3-methyl-4-hydroxyphenyl)-2-methylpentane,
aromatic ring 1,1-Bis(3-methyl-4-hydroxyphenyl)-n-octane,
              1,1-Bis(3-methyl-4-hydroxyphenyl)-2-ethylhexane,
              1,1-Bis(3-methyl-4-hydroxyphenyl)-n-decane,
              1,1-Bis(3-methyl-4-hydroxypheny1)-3,7-dimethyloctane,
              1,1-Bis(3-methyl-4-hydroxyphenyl)-n-dodecane,
              1,1-Bis(3-methyl-4-hydroxyphenyl)-n-tetradecane,

[0079]

TABLE 12
Compound
group         Name of compound
2. Compound   1,1-Bis(3-methyl-4-hydroxyphenyl)-n-hexadecane,
having mono-  1,1-Bis(3-methyl-4-hydroxyphenyl)-n-octadecane, etc.
substituted   1,1-Bis(3-methyl-4-hydroxyphenyl)-n-decane,
aromatic ring 1,1-Bis(3-n-propyl-4-hydroxyphenyl)-n-decane,
(continued    1,1-Bis(3-isopropyl-4-hydroxyphenyl)-n-decane,
from above)   1,1-Bis(3-n-butyl-4-hydroxyphenyl)-n-decane,
              1,1-Bis(3-sec-butyl-4-hydroxyphenyl)-n-decane,
              1,1-Bis(3-isobutyl-4-hydroxyphenyl)-n-decane,
              1,1-Bis(3-tert-butyl-4-hydroxyphenyl)-n-decane,
              1,1-Bis(3-fluoro-4-hydroxyphenyl)-n-decane,
              1,1-Bis(3-chloro-4-hydroxyphenyl)-n-decane,
              1,1-Bis(3-bromo-4-hydroxyphenyl)-n-decane,
              1,1-Bis(3-iodo-4-hydroxyphenyl)-n-decane,
              1,1-Bis(2-methyl-4-hydroxyphenyl)-n-decane,
              1,1-Bis(2-ethyl-4-hydroxyphenyl)-n-decane,
              1,1-Bis(2-chloro-4-hydroxyphenyl)-n-decane,
              1,1-Bis(2-bromo-4-hydroxyphenyl)-n-decane, etc.
3. Compound   1,1-Bis(2,3-dimethyl-4-hydroxyphenyl)-n-decane,
having di-    1,1-Bis(2-methyl-4-hydroxy-5-tert-butylphenyl)-n-
substituted   decane,
aromatic ring 1,1-Bis(2,6-dimethyl-4-hydroxyphenyl)-n-decane,
              1,1-Bis(3,5-dimethyl-4-hydroxyphenyl)-n-decane,
              1,1-Bis(3,5-di-sec-butyl-4-hydroxyphenyl)-n-decane,
              1,1-Bis(3,5-di-tert-butyl-4-hydroxyphenyl)-n-decane, etc.
4. Compound   1,1-Bis(2,3,5-trimethyl-4-hydroxyphenyl)-n-decane,
having tri-   1,1-Bis(2,3,6-trimethyl-4-hydroxyphenyl)-n-decane, etc.
substituted
aromatic ring

[0080] As the light stabilizer which acts as the component (e) there is preferably used any of those listed in Tables 13 to 16.

TABLE 13
Classifi-
cation                          Name of compound
Benzophenone-                   2,4-Dihydroxybenzophenone
based ultraviolet               2-Hydroxy-4-methoxybenzophenone
absorber                        2,2′-Dihydroxy-4,4′-dimethoxybenzophenone
                                2,2′,4,4′-Tetrahydroxybenzophenone
                                2-Hydroxy-4-methoxybenzophenone-5-sulfonic acid
                                2-Hydroxy-4-n-octyloxybenzophenone
                                Bis-(2-methoxy-4-hydroxy-5-benzoylphenyl)-methane
                                2-(2′-Hydroxy-3′-5′-di-t-amylphenyl)-benzophenone
                                2-Hydroxy-4-octadecyloxybenzophenone
                                2-Hydroxy-4-n-dodecyloxybenzophcnone
                                2,2′-Dihydroxy-4-methoxybenzophenone
                                2-Hydroxy-4-benzyloxybenzophenone, etc.
Salicyclic acid-                2-4-Di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate
based ultraviolet               Phenyl salicylate
absorber                        4-t-Butylphenyl salicylate
                                4-t-Octylphenyl salicylate
                                Resorcinol monobenzoate, etc.
Cyano acrylate-                 Ethyl-2-cyano-3,3-diphenyl acrylate
based ultraviolet               2-Ethylhexyl-2-cyano-3,3-diphenyl acrylate
absorber                        2-Ethylhexyl-2-cyano-3-phenylcinnate, etc.
Benzotriazole-based ultraviolet 2-(5-t-Butyl-2-hydroxyphenyl)-benzotriazole
absorber                        2-(5-Methyl-2-hydroxyphenyl)-benzotriazole
                                2-[2-Hydroxy-3,5-bis(a,a-dimethylbenzyl)phenyl]-2H-
                                benzotriazole
                                2-(3,5-Di-t-butyl-2-hydroxyphenyl)-benzotriazole
                                2-(3-t-Butyl-5-methyl-2-hydroxphenyl)-benzotriazole
                                2-(3-Di-t-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole
                                2-(3,5-Di-t-amyl-2-hydroxyphenyl)-benzotriazole
                                Condensate of methyl-3-[3-t-butyl-5-(2H-benzotriazole-2-yl)-4-
                                hydroxyphenyl) propionate with polyethylene glycol having a
                                molecular weight of 300
                                2-(3-Dodecyl-5-methyl-2-hydroxyphenyl)-benzottriazole
                                Condensate of methyl-3-[3-(2H-benzotriazole-2-yl)-5-t-butyl-4
                                hydroxyphenyl)propionate with polyethylene glycol having a
                                molecular weight of 300
                                2-(3-t-Butyl-5-propyloxycarbonylethyl-2-hydroxyphenyl)-5-
                                chlorobenzotriazole
                                2-[2-Hydroxyphenyl-3,5-di-(1,1′-dimethylbenzyl)phenyl]-2H-
                                benzotriazole
                                2-(2-Hydroxy-5-t-octylphenyl)-2H-benzotriazole
                                2-(3-t-Butyl-5-octyloxycarbonylethyl)-2-hydroxyphenyl)-
                                benzotriazole
                                2-(2-Hydroxy-4-octloxy-phenyl)-2H-benzotriazole

[0081]

TABLE 14
Classification            Name of compound
                          2-[2′-Hydroxy-3′-(3′,4′,5′,6′-tetrahydrophthalimidemethyl)-5′-
                          methylphenyl]-benzotriazole
                          2-(2-Hydroxy-5-t-butylphenyl)-benzotriazole, etc.
Oxalic acid anilide-based Ethanediamide-N-(2-ethoxyphenyl)-N′-(4-isododecylphenyl)
ultraviolet absorber      2,2,4,4-Tetramethyl-20-([62 -lauryloxycarbonyl)-ethyl-7-oxa-3,2O-
                          diazadispiro[5,1,11,2)heneicosan-21-one, etc.
Hindered amine-based      Dimethyl[1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-
oxidative inhibitor       tetramethylpiperidine]succinate polycondensate
                          Poly[(6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-
                          diyl)((2,2,6,6-tetramethyl-4-piperidyl) imino)hexamethylene
                          ((2,2,6,6-tetramethyl-4-piperidyl)imino)]
                          2-(3,5-Di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonic acid
                          bis(1,2,2,6,6-pentamethyl-4-piperidyl)
                          N,N′-bis(3-aminopropyl)ethylenediamine-2,4-bis]N-butyl-N-
                          (1,2,2,6,6-pentamethyl-4-piperidyl)amino]-6-chloro-1,3,5-triazine
                          condensate
                          Bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate
                          4-Benzoyloxy-2,2,6,6-tetramethylpiperidine
                          Bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate
                          1-[2-(3-(3 ,5-Di-t-butyl-4-hydroxyphenyl)propionyloxy)ethyl]-4-
                          (3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy)-2,2,6,8-
                          tetramethylpiperidine
                          8-Acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-
                          triazaspiro(4,5)decane-2,4-dione, etc.
Phenol-based oxidative    2,6-Di-t-butyl-4-methylphenol
inhibitor                 Mixture of 2-t-butyl-4-methoxyphenol and 3-t-butyl-4-
                          methoxyphenol
                          2,6-Di-t-butyl-4-ethylphenol
                          Octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate
                          2,2-Methylenebis(4-methyl-6-t-butylphenol)
                          4,4-Thiobis(3-methyl-6-t-butylphenol)
                          2,2-Thiobis(4-methyl-6-t-butylphenol)
                          4,4-butylidenebis(3-methyl-6-t-butylphenol)
                          3,9-Bis[1,1-dimethyl-2-(β-(3-t-butyl--4-hydroxy-5-
                          methylphenyl)propionyloxy)ethyl-4,4,8,10-
                          tetraoxaspiro(5,5)undecane
                          1,1,3-Tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane
                          1,3,5-Trimethyl-2,4,6-tris(3,5-di-t-butyl-4-
                          hydroxybenzyl)benzene
                          Tetrakis[methylene-3-(3′,5′-di-t-hydroxyphenyl)propionate]-
                          methane
                          2,2-Ethylenebis(4,6-di-t-butylphenol)
                          Bis[3,3′-bis-(4′-hydroxy-3′-t-butylphenyl)butyric acid]glycol
                          ester
                          1,3,5-Tris(3′,5′-di-t-butyl-4′-hydroxybenzyl)-S-triazine-2,4,6-
                          (1H,3H,5H)trione

[0082]

TABLE 15
Classification              Name of compound
                            Tocophenol
                            1,3,5-Tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanurate
                            Pentaerythritoltetrakis(3-laurylthiopropionate)
                            Triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-
                            hydroxyphenyl)propionate
                            1,6-Hexanediol-bis[3-(3,5-di-t-butyl-4-
                            hydroxyphenyl)propionate
                            2,2-Thioethylenebis[3-(3,5-di-t-butyl-4-
                            hydroxyphenyl)propionate
                            N,N′-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-
                            hydroxycinnamide)
                            Tris-(3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate
                            Polymerized 2,2,4-trimethyl-1,2-hydroquinone
                            Styrenated phenol
                            2,5-Di-t-butyl hydroquinone
                            2,4-Bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-
                            triazine
                            Octylated diphenylamine, etc.
Sulfur-based oxidative      Dilauryl 3,3′-thiodipropionate
inhibitor                   Dimyristyl 3,3′-thiodipropionate
                            Distearyl 3,3′-thiodipropionate
                            Stearyl thiopropylamide, etc.
Phosphoric acid-based       Tris(2,4-di-t-butylphenyl)phosphite
oxidative inhibitor         Bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite
                            3,5-Di-t-butyl-4-hydroxy-benzyl phosphonate-diethylester
                            Triphenyl phosphite
                            Diphenyl isodecyl phosphite
                            Phenyl dilsodecyl phosphite
                            4,4′-Butylidene-bis(3-methyl-6-t-
                            butylphenylditridecyl)phosphite
                            Octadecyl phosphite
                            Tris(nonylphenyl)phosphite
                            9,10-Dihydro-9-oxa-10-phosphenanethrene-10-oxide
                            10-(3,5-di-t-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-
                            phosphophenanethrene-10-oxide
                            10-Decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanethrene
                            Cyclic neopentatetraylbis(2,4-di-t-butylphenyl)phosphite
                            Cyclic neopentatetraylbis(2,6′-di-t-butyl-4-
                            methylphenyl)phosphite
                            2,2-Methylenebis(4,6-di-t-butylphenyl)octyl phosphite, etc.
Singlet oxidative quenching 1,4-Diazacyclo(2,2,2)octane
agent                       n-Carotene
                            1,3-Cyclohexadiene
                            2-Diethylaminomethylfuran
                            2-Phenylaminometylfuran
                            9-Diethylaminomethylanthracene

[0083]

TABLE 16
Classification	Name of compound
Singlet oxidative quenching	5-Diethylaminomethyl-6-phenyl-3,4-dihydroxypyrane
agent	Nickel dimethyl thiocarbamate
	Nickel dibutyl thiocarbamate
	Nickel-3,5-di-t-butyl-4-hydroxybenzyl-phosphoric acid
	monoethylate
	Nickel-3,5-di-t-butyl-4-hydroxybenzyl-phosphoric acid
	monobutylate
	Nickel[2,2-di-thiobis(4-t-octylphenolate)]-(n-butylamine)
	Nickel[2,2-di-thiobis(4-t-octylphenolate)]-(2-ethylhexylamine)
	Nickelbis[2,2′-thiobis(4-t-octylphenolate)]
	Nickelbis[2,2′-sulfon(4-t-octylphenolate)]
	Nickelbis(2-hydroxy-5-methoxyphenyl-N-n-butylaldoimine
	Nickelbis(dithiobenzyl)
	Nickelbis(dithioacetyl), etc.
Super oxide anion quenching	Complex of super oxide dismutase with cobalt and nickel
agent
Ozone quenching agent	4,4′-Thiobis(6-t-butyl(6-t-butyl-m-cresol)
	2,4,6-Tri-t-butylphenol
	1,4-Diazadicyclo(2,2,2)octane
	N-phenyl-β-naphthylamine
	α-Tocophenol
	4,4′-Methylene-bis(2,6-di-t-butylphenol)
	p,p′-Diaminodiphenylmethane
	2,2′-Methylene-bis(6-t-butyl-P-cresol)
	N,N′-diphenyl-p-phenylenediamine
	N,N′-diphenylethylenediamine
	N-isopropyl-N′-phenyl-p-phenylenediamine, etc.
Visible light absorber	C.I. Solvent Yellow 19, 21, 61
* Dyes	C.I. Solvent Orange 5, 6
	C.I. Solvent Red 8, 24
	C.I. Solvent Violet 14, 21
	C.I. Solvent Blue 11, 25
	C.l. Solvent Black 5, 125, etc.
Visible light absorber]	Color Index No.
* Pigments	10825	21205
	11680	45170
	11725	50440
	11780	58055
	12060	69800
	12120	69810
	12490	70600
	12500	74160
	12710	74265
	21090	127755, etc.
	21110
	21165
	21180

[0084] The metallic lust pigment to be incorporated in the layer of light stabilizer and/or metallic lust pigment layer (f) to be used in the invention is a pigment such as metallic luster pigment, transparent titanium dioxide, transparent iron oxide, transparent cesium oxide and transparent zinc oxide.

[0085] As the metallic lust pigment there may be used a metallic luster pigment having a particle size of from 5 to 100 μm having natural mica coated with titanium oxide or a metallic luster pigment having flat piece of glass coated with titanium oxide. Specific examples of these metallic luster pigments include metallic luster pigment having a particle size of from 5 μm to 60 μm having natural mica coated with from 41 to 44% by weight of titanium oxide, silver metallic luster pigment having a particle size of from 5 μm to 100 μm having natural mica coated with from 16 to 39% by weight of titanium oxide, metallic color luster pigment having natural mica coated with from 45 to 58% by weight of titanium oxide and coated with from 4 to 10% by weight of iron oxide, metallic color luster pigment having natural mica coated with from 45 to 58% by weight of titanium oxide and coated with from 0.5 to 10% by weight of non-thermochromic dyed pigment, and metallic luster pigment having an average thickness of from 1 μm to 10 μm and an average particle size of from 5 μm to 500 μm having flat piece of glass coated with titanium oxide.

[0086] These materials which block mainly ultraviolet rays can be incorporated in the composition in an amount of from 0.1 to 40 parts by weight based on 1 part by weight of the component (a). Alternatively, a layer containing these materials in an amount of from 0.1 to 40 parts by weight may be laminated or used with the thermochromic layer.

[0087] The present invention will be further described in the following examples and comparative examples.

[0088] Processes for the preparation of reversible thermochromic compositions 1 to 16 according to the invention and microcapsuled pigments comprising these compositions incorporated therein will be described hereinafter.

EXAMPLE 1

[0089] Preparation of Reversible Thermochromic Composition 1 and Microcapsuled Pigment Comprising Composition 1 Incorporated Therein

[0090] 1.5 parts by weight of 1,2-benz-6-(N-ethyl-N-isobutylamino)fluoran, 6.0 parts by weight of 2,4-dihydroxy-4′-methylbenzophenone and 50.0 parts by weight of n-nonyl palmitate were mixed. The mixture was then heated to a temperature of 120° C. to melt. Thus, a reversible thermochromic composition 1 was obtained as a homogeneously compatibilized material. To the reversible thermochromic composition 1 were then added 30 parts by weight of an aromatic isocyanate prepolymer and 30 parts by weight of ethyl acetate as wall membrane-forming materials. The mixture was then heated to a temperature of 70° C. to make uniform dissolution. Thus, a mixed solution was prepared. The mixed solution was then stirred in 100 parts by weight of a 5% aqueous solution of gelatin so that it was microfinely emulsified. The emulsion was further stirred for 1 hour. The emulsion was then stirred for 5 hours while being kept at a temperature of 80° C. to obtain a raw solution of microcapsule. The raw solution was then subjected to centrifugal separation to obtain a microcapsuled pigment containing the reversible thermochromic composition 1 which becomes fully colorless at a temperature of not lower than 32° C. and is colored fully pink at a temperature of not higher than 15° C.

EXAMPLES 2-11

[0091] Preparation of Reversible Thermochromic Compositions 2 to 11 and Microcapsuled Pigments Comprising the Compositions 2 to 11 Incorporated Therein

[0092] Reversible thermochromic compositions 2 to 11 and microcapsuled pigments comprising these compositions incorporated therein were obtained in the same manner as the reversible thermochromic composition 1 except that the combination of components (a), (b) and (c) was varied.

[0093] The formulation, color change and discoloration temperature of these reversible thermochromic compositions are set forth in Table 17.

[0094] The figure in parentheses in Table 17 indicate parts by weight.

TABLE 17
				Color change/
Reversible		b. Ultraviolet-absorbing		discoloration
thermochromic		electron accepting	c. Discoloration temperature	temperature
composition	a. Electron donating compound	compound	adjustor	(T1, T4)
1	1,2-Benz-6-(N-ethyl-N-	2,4-Dihydroxy-4′-	n-Nonyl palmitate (50.0)	Pink ←→ colorless
	isobutylamino)fluoran (1.5)	methylbenzophenone (6.0)		15° C., 32° C.
2	1,2-Benz-6-(N-ethyl-N-	2,4-Dihydroxy-4′-n-	n-Nonyl palmitate (50.0)	Pink ←→ colorless
	isobutylamino)fluoran (1.5)	propylbenzophenone (6.0)		15° C., 32° C.
3	1,2-Benz-6-(N-ethyl-N-	2,4-Dihydroxy-4′-n-	n-Nonyl palmitate (50.0)	Pink ←→ colorless
	isobutylamino)fluoran (1.5)	pentylbenzophenone (6.0)		15° C., 32° C.
4	1,2-Benz-6-(N-ethyl-N-	2,4-Dihydroxy-4′-n-	n-Nonyl palmitate (50.0)	Pink ←→ colorless
	isobutylamino)fluoran (1.5)	heptylbenzophenone(6.0)		15° C., 32° C.
5	1,2-Benz-6-(N-ethyl-N-	2,4-Dihydroxy-4′-	n-Nonyl palmitate (50.0)	Pink ←→ colorless
	isobutylamino)fluoran (1.5)	methoxybenzophenone (6.0)		15° C., 320
6	1,2-Benz-6-(N-ethyl-N-	2,4-Dihydroxy-4′-n-	n-Nonyl palmitate (50.0)	Pink ←→ colorless
	isobutylamino)fluoran (1.5)	propoxybenzophenone (6.0)		15° C., 32° C.
7	1,2-Benz-6-(N-ethyl-N-	2,4-Dihydroxy-4′-n-	n-Nonyl palmitate (50.0)	Pink ←→ colorless
	isobutylamino)fluoran (1.5)	pentyloxybenzophenone		15° C., 32° C.
		(6.0)
8	3-(2-Ethoxy-4-N-ethylanilinophenyl)-3-	2,4-Dihydroxy-4′-n-	n-Nonyl palmitate (50.0)	Blue ←→ colorless
	(1-ethyl-2-methyl indol-3-yl)-4-	propylbenzophenone (6.0)		15° C., 32° C.
	azaphthalide (1.5)
9	2,6-Bis(2-butoxyphenyl)-4-(4-dimethyl	2,4-Dihydroxy-4′-n-	n-Nonyl palmitate (50.0)	Yellow ←→ colorless
	aminophenyl)pyridine (1.5)	propylbenzophenone(6.0)		15° C., 32° C.
10	1,2Benz-6-(N-ethyl-N-	2,4-Dihydroxy-4′-n-	Stearyl laurate (50.0)	Pink ←→ colorless
	isobutylamino)fluoran (1.5)	propylbenzophenone(6.0)		37° C., 42° C.
11	1,2-Benz-6-(N-ethyl-N-	2,4-Dihydroxybenzophenone	n-Butyl stearate (50.0)	Pink ←→ colorless
	isobutylamino)fluoran (1.5)	(6.0)		18° C., 22° C.

EXAMPLES 12-14

[0095] Preparation of Reversible Thermochromic Compositions 12 to 14 and Microcapsuled Pigments Comprising the Compositions 12 to 14 Incorporated Therein

[0096] Reversible thermochromic compositions 12 to 14 and microcapsuled pigments comprising these compositions incorporated therein were obtained in the same manner as the reversible thermochromic composition 2 except that to the components (a), (b) and (c) was added a component (d).

[0097] The formulation of these reversible thermochromic compositions are set forth in Table 18.

[0098] Since as the components (a), (b) and (c) there were used the same compounds as used for the reversible thermochromic composition 2, the parts by weight of these components used are set forth in Table 18.

TABLE 18
Reversible	Components (a), (b)
thermo-	and (c) as used for		Color change/dis-
chromic	reversible thermo-		coloration
com-	chromic composition 2	(d) Light-fastness	temperature (T1,
position	a	b	c	providing agent	T4)
12	(1.5)	(2.0)	(50.0)	1,1-Bis(4-	Pink←→colorless
				hydroxyphenyl)-	15° C., 32° C.
				n-decane (4.0)
13	(1.5)	(3.0)	(50.0)	1,1-Bis(4-	Pink←→colorless
				hydroxyphenyl)-	15° C., 32° C.
				n-decane (3.0)
14	(1.5)	(4.0)	(50.0)	1,1-Bis(4-	Pink←→colorless
				hydroxyphenyl)-	15° C., 32° C.
				n-decane (2.0)

EXAMPLES 15-16

[0099] Preparation of Reversible Thermochromic Compositions 15 and 16 and Microcapsuled Pigments Comprising the Compositions 15 and 16 Incorporated Therein

[0100] Reversible thermochromic compositions 15 and 16 and microcapsuled pigments comprising these compositions incorporated therein were obtained in the same manner as the reversible thermochromic composition 2 except that to the components (a), (b) and (c) were added components (d) and (e).

[0101] The formulation of these reversible thermochromic compositions are set forth in Table 19.

[0102] Since as the components (a), (b) and (c) there were used the same compounds as used for the reversible thermochromic composition 2, the parts by weight of these components used are set forth in Table 19.

TABLE 19
	Components (a), (b) and (c) as
Reversible	used for reversible thermo-
thermochromic	chromic composition 2	(d) Light-fastness		Color/discoloration
composition	a	b	c	providing agent	(e) Light stabilizer	temperature (T1, T4)
15	(1.5)	(3.0)	(50.0)	1,1-Bis(4-	2-(3-t-Butyl-5-methyl-2-	Pink←→colorless
				hydroxyphenyl)-n-decane	hydroxyphenyl)-5-	15° C., 32° C.
				(3.0)	chlorobenzotriazole (0.5)
					2-(3,5-Di-t-butyl-4-
					hydroxybenzyl)-2-n-
					butylmalonic acid
					bis(1,2,2,6,6-penta-
					methyl-4-piperidyl) (0.5)
16	(1.5)	(2.0)	(50.0)	1,1-Bis(4-	2-(3-t-Butyl-5-methyl-2-	Pink←→colorless
				hydroxyphenyl)-n-decane	hydroxyphenyl)-5-	15° C., 32° C.
				(4.0)	chlorobenzotriazole (1.5)
					2-(3,5-Di-t-butyl-4-
					hydroxybenzyl)-2-n-
					butylmalonic acid
					bis(1,2,2,6,6-penta-
					methyl-4-piperidyl) (0.5)

[0103] Performance Test

[0104] In order to explain the effect of the reversible thermochromic compositions of Examples 1 to 16, light-fastness test specimens 1 to 16 obtained by forming a reversible thermochromic layer of microcapsuled pigments containing these compositions on a synthetic paper were subjected to performance test.

[0105] Preparation of Light-fastness Specimen 1

[0106] 43 .0 parts by weight of a microcapsuled pigment comprising the reversible thermochromic composition 1 of Example 1 incorporated therein were uniformly stirred in a vehicle consisting of 50.0 parts by weight of an ethylene-vinyl acetate copolymer resin emulsion, 3.0 parts by weight of an anti-foaming agent, 1.0 part by weight of a thickening agent (sodium alginate), 3.0 parts by weight of a leveling agent and 1.0 part by weight of a preservative to obtain a reversible thermochromic screen ink.

[0107] The foregoing reversible thermochromic screen ink was then screen-printed on a synthetic white paper to prepare a reversible thermochromic print as a light-fastness test specimen 1.

[0108] Preparation of Light-fastness Test Specimens 2-16

[0109] Light-fastness test specimens 2 to 16 were prepared from microcapsuled pigments comprising the reversible thermochromic compositions 2 to 16 of Examples 2 to 16 incorporated therein in the same manner as the light-fastness test specimen 1.

[0110] The process for the preparation of light-fastness test specimens 17 to 21 having a layer of a light stabilizer and/or metallic luster pigment (f) provided on a reversible thermochromic layer of microcapsuled pigments comprising the reversible thermochromic compositions 2, 13 and 15 incorporated therein formed on a synthetic paper, respectively, will be described hereinafter.

[0111] Preparation of Light-fastness Test Specimen 17

[0112] 43 .0 parts by weight of a microcapsuled pigment comprising the reversible thermochromic composition 2 of Example 2 made of the components (a), (b) and (c) were uniformly stirred in a vehicle containing 50.0 parts by weight of an ethylene-vinyl acetate copolymer resin emulsion, 3.0 parts by weight of an anti-foaming agent, 1.0 part by weight of a thickening agent (sodium alginate), 3.0 parts by weight of a leveling agent and 1.0 part by weight of a preservative to obtain a reversible thermochromic screen ink.

[0113] The foregoing reversible thermochromic screen ink was then screen-printed on a synthetic white paper to form a reversible thermochromic layer thereon. A screen ink obtained by uniformly stirring 5.0 parts by weight of 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole as a light stabilizer in a vehicle consisting of 50 parts by weight of an acrylic resin solution (solid content: 50%; xylene: 50%), 45 parts by weight of cyclohexanone, 3.0 parts by weight of a leveling agent, 1.0 part by weight of an anti-foaming agent and 1.0 part by weight of a viscosity modifier was then printed on the reversible thermochromic layer to form a layer of a light stabilizer (f). Thus, a light-fastness test specimen 17 was prepared.

[0114] Preparation of Light-fastness Test Specimen 18

[0115] 43 .0 parts by weight of a microcapsuled pigment comprising the reversible thermochromic composition 13 of Example 13 made of the components (a), (b), (c), and (d) were uniformly stirred in a vehicle consisting of 50.0 parts by weight of an ethylene-vinyl acetate copolymer resin emulsion, 3.0 parts by weight of an anti-foaming agent, 1.0 part by weight of a thickening agent (sodium alginate), 3.0 parts by weight of a leveling agent and 1.0 part by weight of a preservative to obtain a reversible thermochromic screen ink.

[0116] The foregoing reversible thermochromic screen ink was then screen-printed on a synthetic white paper to form a reversible thermochromic layer thereon. A screen ink obtained by uniformly stirring 5.0 parts by weight of 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole as a light stabilizer in a vehicle consisting of 50 parts by weight of an acrylic resin solution (solid content: 50%; xylene: 50%), 45 parts by weight of cyclohexanone, 3.0 parts by weight of a leveling agent, 1.0 part by weight of an anti-foaming agent and 1.0 part by weight of a viscosity modifier was then printed on the reversible thermochromic layer to form a layer of a light stabilizer (f). Thus, a light-fastness test specimen 18 was prepared.

[0117] Preparation of Light-fastness Test Specimen 19

[0118] 43 .0 parts by weight of a microcapsuled pigment comprising the reversible thermochromic composition 15 of Example 15 made of the components (a), (b), (c), (d) and (e) were uniformly stirred in a vehicle consisting of 50.0 parts by weight of an ethylene-vinyl acetate copolymer resin emulsion, 3.0 parts by weight of an anti-foaming agent, 1.0 part by weight of a thickening agent (sodium alginate), 3.0 parts by weight of a leveling agent and 1.0 part by weight of a preservative to obtain a reversible thermochromic screen ink.

[0119] The foregoing reversible thermochromic screen ink was then screen-printed on a synthetic white paper to form a reversible thermochromic layer thereon. A screen ink obtained by uniformly stirring 5.0 parts by weight of 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole as a light stabilizer in a vehicle consisting of 50 parts by weight of an acrylic resin solution (solid content: 50%; xylene: 50%), 45 parts by weight of cyclohexanone, 3.0 parts by weight of a leveling agent, 1.0 part by weight of an anti-foaming agent and 1.0 part by weight of a viscosity modifier was then printed on the reversible thermochromic layer to form a layer of a light stabilizer (f). Thus, a light-fastness test specimen 19 was prepared.

[0120] Preparation of Light-fastness Test Specimen 20

[0121] 43 .0 parts by weight of a microcapsuled pigment comprising the reversible thermochromic composition 15 of Example 15 made of the components (a), (b), (c), (d) and (e) were uniformly stirred in a vehicle consisting of 50.0 parts by weight of an ethylene-vinyl acetate copolymer resin emulsion, 3.0 parts by weight of an anti-foaming agent, 1.0 part by weight of a thickening agent (sodium alginate), 3.0 parts by weight of a leveling agent and 1.0 part by weight of a preservative to obtain a reversible thermochromic screen ink.

[0122] The foregoing reversible thermochromic screen ink was then screen-printed on a synthetic white paper to form a reversible thermochromic layer thereon. A screen ink obtained by uniformly stirring 1.5 parts by weight of a metallic luster pigment (trade name: Iriodin 219, produced by Merck Japan Ltd.) in a vehicle consisting of 45 parts by weight of cyclohexanone, 3.0 parts by weight of a leveling agent, 1.0 part by weight of an anti-foaming agent and 1.0 part by weight of a viscosity modifier was then printed on the reversible thermochromic layer to form a layer of a metallic luster pigment (f). Thus, a light-fastness test specimen 20 was prepared.

[0123] Preparation of Light-fastness Test Specimen 21

[0124] 43 .0 parts by weight of a microcapsuled pigment comprising the reversible thermochromic composition 15 of Example 15 made of the components (a), (b), (c), (d) and (e) were uniformly stirred in a vehicle consisting of 50.0 parts by weight of an ethylene-vinyl acetate copolymer resin emulsion, 3.0 parts by weight of an anti-foaming agent, 1.0 part by weight of a thickening agent (sodium alginate), 3.0 parts by weight of a leveling agent and 1.0 part by weight of a preservative to obtain a reversible thermochromic screen ink.

[0125] The foregoing reversible thermochromic screen ink was then screen-printed on a synthetic white paper to form a reversible thermochromic layer thereon. A screen ink obtained by uniformly stirring 1.5 parts by weight of a metallic luster pigment (trade name: Iriodin 219, produced by Merck Japan Ltd.) and 5.0 parts by weight of 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole as a light stabilizer in a vehicle consisting of 50 parts by weight an acrylic resin solution (solid content: 50%; xylene] 50%), 45 parts by weight of cyclohexanone, 3.0 parts by weight of a leveling agent, 1.0 part by weight of an anti-foaming agent and 1.0 part by weight of a viscosity modifier was then printed on the reversible thermochromic layer to form a layer of a light stabilizer and a metallic luster pigment (f). Thus, a light-fastness test specimen 21 was prepared.

Comparative Examples 1-5

[0126] The process for the preparation of reversible thermochromic compositions 17 to 21 of Comparative Examples 1 to 5 to be used in Comparative Examples 1 to 5, respectively, and microcapsuled pigments comprising the compositions incorporated therein will be described hereinafter.

[0127] Preparation of Reversible Thermochromic Composition 17 of Comparative Example 1 and Microcapsuled Pigment Comprising the Composition 17 Incorporated Therein

[0128] 1.5 parts by weight of 1,2-benz-6-(N-ethyl-N-isobutylamino)fluoran, 6.0 parts by weight of 2,4-bis(4-dihydroxyphenyl) and 50.0 parts by weight of n-nonyl palmitate were mixed. The mixture was then heated to a temperature of 120° C. to melt. Thus, a reversible thermochromic composition 17 was obtained as a homogeneously compatibilized material. To the reversible thermochromic composition 17 were then added 30 parts by weight of an aromatic isocyanate prepolymer and 30 parts by weight of ethyl acetate as wall membrane-forming materials. The mixture was then heated to a temperature of 70° C. to make uniform dissolution. Thus, a mixed solution was prepared. The mixed solution was then stirred in 100 parts by weight of a 5% aqueous solution of gelatin so that it was microfinely emulsified. The emulsion was further stirred for 1 hour. The emulsion was then stirred for 5 hours while being kept at a temperature of 80° C. to obtain a raw solution of microcapsule. The raw solution was then subjected to centrifugal separation to obtain a microcapsuled pigment containing the reversible thermochromic composition 17 which becomes fully colorless at a temperature of not lower than 32° C. and is colored fully pink at a temperature of not higher than 15° C.

[0129] Preparation of Reversible Thermochromic Compositions 18 to 21 of Comparative Examples 2 to 5 and Microcapsuled Pigments Comprising the Composition 18 to 21 Incorporated Therein

[0130] Reversible thermochromic compositions 18 and 19 of Comparative Examples 2 and 3 and microcapsuled pigments comprising the compositions 18 and 19 incorporated therein were obtained in the same manner as the reversible thermochromic composition 17 except that the various components were changed.

[0131] Reversible thermochromic compositions 20 and 21 and microcapsuled pigments comprising the compositions 20 and 21 incorporated therein were obtained in the same manner as the reversible thermochromic composition 17 of Comparative Example 1 except that to the various components used was added a component (e).

[0132] The formulation of the reversible thermochromic compositions 17 to 21 of Comparative Examples 1 to 5 are set forth in Table 20.

[0133] The symbol “B” in the constituents in Table 20 indicates a conventional electron accepting compound.

TABLE 20
Reversible					Color change/
thermochromic	a. Electron donating	B. Electron accepting	c. Discoloration		discoloration
composition	compound	compound	temperature adjustor	e. Light stabilizer	temperature (T1, T4)
17	1,2-Benz-6-(N-ethyl-	2,2-Bis(4-	n-Nonyl palmitate		Pink ←→ colorless
	isobutylamino)fluoran	hydroxyphenyl)propane	(50.0)		15° C., 32° C.
	(1.5)	(6.0)
18	3-(2-Ethoxy-4-N-	2,2-Bis(4-	n-Nonyl palmitate		Blue ←→ colorless
	ethylanilinophenyl)-3-(1-	hydroxyphenyl)propane	(50.0)		15° C., 32° C.
	ethyl-2-methylindol-3-	(6.0)
	yl)-4-azaphthalide (1.5)
19	2,6-Bis(2-	2,2-Bis(4-	n-Nonyl palmitate		Yellow ←→ colorless
	butoxyphenyl)-4-(4-	hydroxyphenyl)hexafluoro	(50.0)		15° C., 32° C.
	dimethylaminophenyl)-	propane (6.0)
	pyridine (1.5)
20	1,2-Benz-6-(N-ethyl-N-	2,2-Bis(4-	n-Nonyl palmitate	2-(5-t-Butyl-2-	Pink ←→ colorless
	isobutylamino(fluroan	hydroxypenyl)propane	(50.0)	hydroxyphenyl)benzo	15° C., 32° C.
	(1.5)	(6.0)		triazole (1.0)
21	1,2-Benz-6-(N-ethyl-N-	2,2-Bis(4-	n-Nonyl palmitate	2-(5-t-Butyl-2-	Pink ←→ coloreless
	isobutylamino)fluoran	hydroxyphenyl)propane	(50.0)	hydroxyphenyl)benzo	12° C., 32° C.
	(1.5)	(6.0)		triazole (5.0)

[0134] The preparation of comparative light-fastness test specimens 22 to 26 having a reversible thermochromic layer of microcapsuled pigments containing the foregoing comparative reversible thermochromic compositions 17 to 21 formed on a synthetic paper, respectively, will be described hereinafter.

[0135] Preparation of Comparative Light-fastness Test Specimen 22

[0136] 43 .0 parts by weight of a microcapsuled pigment comprising the reversible thermochromic composition 17 of Comparative Example 1 incorporated therein were uniformly stirred in a vehicle consisting of 50.0 parts by weight of an ethylene-vinyl acetate copolymer resin emulsion, 3.0 parts by weight of an anti-foaming agent, 1.0 part by weight of a thickening agent (sodium alginate), 3.0 parts by weight of a leveling agent and 1.0 part by weight of a preservative to obtain a reversible thermochromic screen ink.

[0137] The foregoing reversible thermochromic screen ink was then screen-printed on a synthetic white paper to prepare a reversible thermochromic print having a reversible thermochromic layer formed thereon as a light-fastness test specimen 22.

[0138] Preparation of Comparative Light-fastness Test Specimens 23-26

[0139] Light-fastness test specimens 23 to 26 were prepared in the same manner as the light-fastness test specimen 22 except that microcapsuled pigments having the reversible thermochromic compositions 18 to 21 of Comparative Examples 2 to 5 incorporated therein were prepared, respectively.

[0140] Testing Method for Light-fastness in Quenched State

[0141] Using a Type SUNTEST CPS xenon arc lamp testing machine (produced by Herennius Inc. of Germany), test specimens 1 to 21 comprising reversible thermochromic compositions of the invention and test specimens 22 to 26 comprising comparative reversible thermochromic compositions were examined for light-fastness in quenched state.

[0142] For the light-fastness test, the radiant intensity of the xenon arc lamp was adjusted to 70,000 lux, and the distance between the light source and the test specimen was predetermined to 21 cm.

[0143] For the test, the test specimens 1 to 16 and the test specimens 22 to 26 were each irradiated with light from the xenon arc lamp on four points on the surface thereof for 5 hours, 10 hours, 15 hours and 20 hours.

[0144] The test specimens 17 to 21 were each irradiated with light from the xenon arc lamp on four points on the surface thereof for 10 hours, 20 hours, 30 hours and 40 hours.

[0145] Results of Light-fastness Test

[0146] Table 21 shows the results of light-fastness test in quenched state on the test specimens 1 to 11 comprising the reversible thermochromic compositions of Examples 1 to 11 made of the components (a), (b) and (c) of the invention.

[0147] The term “composition” as used in Table 21 indicates the reversible thermochromic composition incorporated in the test specimen. The term “constituent element” as used in Table 21 indicates various components (a) to (e) incorporated in the composition and the layer (f) of light stabilizer and/or metallic luster pigment provided on the thermochromic layer.

TABLE 21
Test		Con-
speci-		stituent	Unir-	5	10	15	20
men	Composition	element	radiated	hours	hours	hours	hours
1	Reversible	a, b, c	100%	94%	76%	63%	43%
	thermochromic
	composition 1
2	Reversible	a, b, c	100%	97%	81%	65%	45%
	thermochromic
	composition 2
3	Reversible	a, b, c	100%	98%	85%	70%	51%
	thermochromic
	composition 3
4	Reversible	a, b, c	100%	98%	86%	69%	50%
	thermochromic
	composition 4
5	Reversible	a, b , c	100%	93%	74%	62%	42%
	thermochromic
	composition 5
6	Reversible	a, b, c	100%	96%	79%	64%	43%
	thermochromic
	composition 6
7	Reversible	a, b, c	100%	97%	82%	67%	50%
	thermochromic
	composition 7
8	Reversible	a, b, c	100%	99%	95%	89%	74%
	thermochromic
	composition 8
9	Reversible	a, b, c	100%	89%	78%	62%	45%
	thermochromic
	composition 9
10	Reversible	a, b, c	100%	97%	82%	67%	46%
	thermochromic
	composition 10
11	Reversible	a, b, c	100%	90%	69%	55%	38%
	thermochromic
	composition 11

[0148] Table 22 shows the results of light-fastness test in quenched state on the test specimens 12 to 14 comprising the reversible thermochromic compositions of Examples 12 to 14 made of the components (a), (b), (c) and (d) of the invention.

TABLE 22
Test		Con-
speci-		stituent	Unir-	5	10	15	20
men	Composition	element	radiated	hours	hours	hours	hours
12	Reversible	a, b, c, d	100%	100%	99%	96%	92%
	thermochromic
	composition 12
13	Reversible	a, b, c, d	100%	100%	98%	95%	90%
	thermochromic
	composition 13
14	Reversible	a, b, c, d	100%	100%	97%	93%	88%
	thermochromic
	composition 14

[0149] Table 23 shows the results of light-fastness test in quenched state on the test specimens 15 and 16 comprising the reversible thermochromic compositions of Examples 15 and 16 made of the components (a), (b), (c), (d) and (e) of the invention.

TABLE 23
Test		Con-
speci-		stituent	Unir-	5	10	15	20
men	Composition	element	radiated	hours	hours	hours	hours
15	Reversible	a, b, c, d,	100%	100%	100%	98%	94%
	thermochromic	e
	composition 15
16	Reversible	a, b, c, d,	100%	100%	100%	99%	96%
	thermochromic	e
	composition 16

[0150] Table 24 shows the results of light-fastness test in quenched state on the test specimens 17 to 21 having a layer of light stabilizer and/or metallic lust pigment (f) provided on the reversible thermochromic layer formed by the reversible thermochromic compositions of Examples 2, 13 and 15 of the invention.

TABLE 24
Test		Con-
speci-		stituent	Unir-	10	20	30	40
men	Composition	element	radiated	hours	hours	hours	hours
17	Reversible	a, b, c,	100%	100%	99%	89%	69%
	thermo-	f (layer of
	chromic	light
	composition	stabilizer)
	2
18	Reversible	a, b, c, d	100%	100%	100%	96%	87%
	thermo-	f (layer of
	chromic	light
	composition	stabilizer
	13
19	Reversible	a, b, c, d, e,	100%	100%	100%	97%	91%
	thermo-	f (layer of
	chromic	light
	composition	stabilizer
	15
20	Reversible	a, b, c, d, e,	100%	100%	100	99%	95%
	thermo-	f (layer of
	chromic	light
	composition	metallic
	15	luster
		pigment)
21	Reversible	a, b, c, d, e	100%	100%	100%	100%	99%
	thermo-	f (layer of
	chromic	light
	composition	stabilizer and
	15	metallic
		luster
		pigment)

[0151] Table 25 shows the results of light-fastness test in quenched state on the test specimens 22 to 26 comprising the reversible thermochromic compositions 17 to 21 of Comparative Examples 1 to 5.

TABLE 25
Test		Con-
speci-		stituent	Unir-	5	10	15	20
men	Composition	element	radiated	hours	hours	hours	hours
22	Reversible	a, B, c	100%	72%	40%	30%	16%
	thermochromic
	composition 17
23	Reversible	a, B, c	100%	52%	15%	10%	7%
	thermochromic
	composition 18
24	Reversible	a, B, c	100%	68%	35%	21%	12%
	thermochromic
	composition 19
25	Reversible	a, B, c, e	100%	89%	53%	35%	24%
	thermochromic
	composition 20
26	Reversible	a, B, c, e	100%	95%	80%	65%	46%
	thermochromic
	composition 21

[0152] As can be seen in the foregoing results of light-fastness test in quenched state, the reversible thermochromic compositions 1 to 16 comprising the components (a), (b) and (c) of the invention are remarkably excellent in light-fastness as compared with the reversible thermochromic compositions 17 to 21 comprising conventional components (a), B and (c).

[0153] Further, the addition of the component (d) to the reversible thermochromic composition comprising the components (a), (b) and (c) makes it possible to improve the light-fastness in quenched state because the electron donating compound has a weak interaction with the ultraviolet-absorbing electron accepting compound (b) and the light-fastness providing agent (d) while being dissolved in the discoloration temperature adjustor (c). Moreover, the addition of the component (e) makes it possible to further improve the light-fastness of the reversible thermochromic composition.

[0154] Further, the provision of a layer of light stabilizer or metallic luster pigment on the surface of the foregoing layer formed by the reversible thermochromic composition makes it possible to further improve the light-fastness of the reversible thermochromic composition in quenched state.

[0155] Discoloration Sensitivity Test

[0156] The test specimen 2 comprising the reversible thermochromic composition of Example 2 made of the components (a), (b) and (c) of the invention and the test specimen 26 comprising the reversible thermochromic composition 21 of Comparative Example 5 having a large amount of the component (e) added to conventional reversible thermochromic composition were subjected unirradiated to discoloration test on heating and cooling in the following manner. The resulting discoloration behavior was then plotted on a graph to determine discoloration sensitivity.

[0157] The various test specimens were each stuck to a Type TC-3600 color difference meter (produced by Tokyo Denshoku K.K.) at a predetermined position. The prints were then each heated and cooled at a rate of 10° C./min within a temperature range of 50° C.

[0158] The brightness value indicated on the color difference meter at various temperatures were then plotted on a graph to draw color density-temperature curve. Thus, various values of T1 (full color development temperature), T2 (color development starting temperature), T3 (quenching starting temperature) and T4 (full quenching temperature) were determined.

[0159] FIG. 1 indicates the color density-temperature curve of the test specimen 2 of Example 2. The color density-temperature curve shows that T1 is 15° C., T2 is 18° C., T3 is 28° C. and T4 is 32° C.

[0160] FIG. 2 indicates the color density-temperature curve of the test specimen 26 of Comparative Example 5. The color density-temperature curve shows that T1 is 12° C., T2 is 18° C., T3 is 22° C. and T4 is 32° C.

[0161] The smaller the difference between T2 and T1 (T2-T1) and the difference between T4 and T3 (T4-T3) are, the more sensitivity the reversible thermochromic composition discolors and the better is discoloration sensitivity.

[0162] The temperature difference (T2-T1) and (T4-T3) of the test specimen 2 are 3° C. and 4° C., respectively. On the contrary, the temperature difference (T2- T1) and (T4- T3) of the test specimen 26 are 6° C. and 10° C., respectively. This demonstrates that the reversible thermochromic composition of the invention has a high discoloration sensitivity.

[0163] Besides the light-fastness test in quenched state and discoloration test on the foregoing reversible thermochromic compositions of the invention and the conventional reversible thermochromic compositions, the reversible thermochromic compositions of the invention were each subjected to light-fastness test in color-developed state.

[0164] As test specimens there were used the test specimen 2 comprising the reversible thermochromic composition of Example 2 made of the components (a), (b) and (c), the test specimens 12 to 14 comprising the reversible thermochromic compositions of Examples 12 to 14 made of the components (a), (b), (c) and (d), the test specimen 15 of Example 15 comprising the reversible thermochromic composition made of the components (a), (b), (c), (d) and (e), and the test specimens 20 and 21 having a layer of light stabilizer and/or metallic luster pigment (f) provided on the reversible thermochromic layer formed by the reversible thermochromic composition of Example 15 made of the compositions (a), (b), (c), (d) and (e).

[0165] The test specimens 2 and 12 to 15 were each irradiated with light from xenon arc lamp at four points for 5 hours, 10 hours, 15 hours and 20 hours for measurement.

[0166] The test specimens 20 and 21 were each irradiated with light from xenon arc lamp at four points for 10 hours, 20 hours, 30 hours and 40 hours for measurement.

[0167] Table 26 shows the results of light-fastness test on the test specimens 2 and 12 to 15 in color-developed state.

TABLE 26
Test		Con-
speci-		stituent	Unir-	5	10	15	20
men	Composition	element	radiated	hours	hours	hours	hours
2	Reversible	a, b, c	100%	55%	28%	19%	15%
	thermochromic
	composition 2
12	Reversible	a, b, c, d	100%	97%	93%	90%	85%
	thermochromic
	composition 12
13	Reversible	a, b, c, d	100%	100%	98%	96%	94%
	thermochromic
	composition 13
14	Reversible	a, b, c, d	100%	100%	99%	97%	95%
	thermochromic
	composition 14
15	Reversible	a, b, c, d,	100%	100%	100%	98%	96%
	thermochromic	e
	composition 15

[0168] Table 27 shows the results of light-fastness test in color-developed state on the test specimens 20 and 21.

TABLE 27
Test		Con-
speci-		stituent	Unir-	10	20	30	40
men	Composition	element	radiated	hours	hours	hours	hours
20	Reversible	a, b, c, d, e,	100%	100%	100%	100%	99%
	thermo-	f (layer of
	chromic	metallic
	composition	luster
	15	pigment)
21	Reversible	a, b, c, d, e	100%	100%	100%	100%	99%
	thermo-	f (layer of
	chromic	light
	composition	stabilizer and
	15	metallic
		luster
		pigment)

[0169] The percent color density retention in the foregoing results of light-fastness test will be described hereinafter.

[0170] The various test specimens were each measured for density stimulation value (X value) unirradiated or after irradiated for a predetermined period of time using a Type TC-3600 color difference meter (produced by Tokyo Denshoku K.K.).

[0171] The percent color density was calculated by the following equation:

% Color density retention=[100−stimulation value (X) after irradiated]/[100−stimulation value (X) before irradiated]×100

[0172] Referring to light-fastness in color-developed state, as indicated by the percent color density retention in the table above, the reversible thermochromic composition having the component (d) added thereto exhibits a better light-fastness in color-developed state than the reversible thermochromic composition comprising the components (a), (b) and (c). The further provision of the layer of light stabilizer and/or metallic luster pigment (f) gives a better light-fastness in color-developed state.

[0173] As can be seen in the foregoing results of light-fastness test in color-developed state, the addition of the component (d) to the reversible thermochromic composition comprising the components (a), (b), and (c) makes it possible to improve the light-fastness during color development.

[0174] Examples of ink, fiber treatment, coating compound, cosmetics and molding resin composition made of microcapsuled pigment having the reversible thermochromic composition of the invention incorporated therein will be described hereinafter.

EXAMPLE 17

[0175] Ink for Writing Utensils Containing Reversible Thermochromic Composition 2 and Writing Utensils Comprising Same

[0176] 25.0 parts by weight of a microcapsuled pigment having the reversible thermochromic composition 2 incorporated therein were uniformly dispersed in a vehicle consisting of 5.0 parts by weight of glycerin, 0.7 parts by weight of a mildewproofing agent, 0.1 parts by weight of a silicone-based anti-foaming agent and 68.2 parts by weight of water to obtain a reversible thermochromic aqueous ink.

[0177] An ink-absorbing material having a polyester sliver coated with a synthetic resin film was then impregnated with the foregoing reversible thermochromic aqueous ink composition. The ink-absorbing material was then received in a cylinder in such an arrangement that it was connected to a pen formed by a polyester resin fiber mounted on the forward end of the cylinder to prepare writing utensils.

[0178] The writing made by the writing utensils became colorless when heated to a temperature of not lower than 32° C. but assumed pink at a temperature of not higher than 15° C.

[0179] The writing exhibited an improved light-fastness and a high discoloration sensitivity similarly to the light-fastness test specimen 2.

EXAMPLE 18

[0180] Screen Ink Containing Reversible Thermochromic Composition 8 and Sheet Comprising Same

[0181] 40.0 parts by weight of a microcapsuled pigment having the reversible thermochromic composition 8 incorporated therein were uniformly dispersed in a vehicle consisting of 50.0 parts by weight of an ethylene-vinyl acetate copolymer resin emulsion, 3.0 parts by weight of an anti-foaming agent, 1.0 part by weight of a thickening agent (sodium alginate), 3.0 parts by weight of a leveling agent, and 1.0 part by weight of a mildewproofing agent to obtain a reversible thermochromic screen ink.

[0182] The foregoing screen ink was then printed on a support obtained by applying an adhesive to a synthetic white paper having a thickness of 80 μm, and then laminating a polyethylene foam having a thickness of 1 mm thereon using a 150-mesh screen made of polyester to form a reversible thermochromic layer thereon. Thus, a reversible thermochromic sheet was obtained.

[0183] The foregoing sheet assumed white on the whole surface thereof when heated to a temperature of not lower than 32° C. but assumed blue at a temperature of not higher than 15° C.

[0184] The foregoing sheet exhibited an improved light-fastness and an excellent discoloration sensitivity similarly to the light-fastness test specimen 8.

EXAMPLE 19

[0185] Fiber Treatment Containing Reversible Thermochromic Composition 13 and Stuffed Doll Comprising Same

[0186] 20.0 parts by weight of a microcapsuled pigment having the reversible thermochromic composition 13 incorporated therein were uniformly dispersed in a vehicle consisting of 80.0 parts by weight of an acrylic acid ester resin emulsion, 0.5 parts by weight of an anti-foaming agent, and 0.5 parts by weight of a leveling agent to obtain a reversible thermochromic aqueous coating solution.

[0187] 100.0 parts by weight of a raw cotton of polyacrylonitrile with 7 denier having a length of 70 mm were then dipped in the foregoing reversible thermochromic aqueous coating solution. Thereafter, the raw cotton was subjected to centrifugal separation so that excess coating solution was removed, and then dried at a temperature of 90° C. for 10 minutes to obtain a raw cotton of reversible thermochromic polyacrylonitrile.

[0188] The foregoing raw cotton of reversible thermochromic polyacrylonitrile was then carded to form a sliver. The sliver thus formed was knitted by a hi-pile knitting machine. The knitted material was sheared to obtain a reversible thermochromic hi-pile cloth having a pile length of 20 mm.

[0189] The reversible thermochromic hi-pile cloth thus obtained was then subjected to sewing to obtain a reversible thermochromic stuffed doll of bear.

[0190] The stuffed doll thus obtained assumed white when heated to a temperature of not lower than 32° C. but assumed pink at a temperature of not higher than 15° C.

[0191] The stuffed doll exhibited an improved light-fastness and an excellent discoloration sensitivity similarly to the light-fastness test specimen 13.

EXAMPLE 20

[0192] Spray Coating Compound Containing Reversible Thermochromic Composition 15 and Miniaturized Car Comprising Same

[0193] 25.0 parts by weight of a microcapsuled pigment having the reversible thermochromic composition 15 incorporated therein were uniformly dispersed in a vehicle consisting of 50.0 parts by weight of an acrylic resin solution (solid content: 40%; toluene: 60%), 49.0 parts by weight of methyl isobutyl ketone and 1.0 part by weight of a leveling agent. The dispersion thus obtained was then filtered through a 180-mesh stainless steel screen to obtain a reversible thermochromic spray coating compound.

[0194] The foregoing reversible thermochromic spray coating compound was sprayed onto a white miniaturized car through a spray gun having an aperture diameter of 0.6 mm, and then dried to form a reversible thermochromic layer thereon. Onto the reversible thermochromic layer was then sprayed a metallic luster spray coating compound having 1.5 parts by weight of a metallic luster pigment (trade name: Iriodin 219, produced by Merck Japan Ltd.) uniformly dispersed in a vehicle consisting of 50.0 parts by weight of an acrylic resin solution (solid content: 40%; toluene: 60%), 49.0 parts by weight of toluene and 1.0 part by weight of a leveling agent. The coated miniaturized car was then dried to obtain a reversible thermochromic miniaturized car having a metallic luster pigment layer provided thereon.

[0195] The foregoing miniaturized car assumed white when heated to a temperature of 32° C. but assumed metallic pink at a temperature of not higher than 15° C.

[0196] The foregoing miniaturized car exhibited an improved light-fastness and an excellent discoloration sensitivity similarly to the light-fastness test specimen 20.

EXAMPLE 21

[0197] Cosmetic Containing Reversible Thermochromic Composition 15 and False Nail Comprising Same

[0198] 15.0 parts by weight of a microcapsuled pigment comprising the reversible thermochromic composition 15 incorporated therein were stirred in a vehicle consisting of 40.0 parts by weight of an acrylic polyol resin solution (solid content: 50%; xylene: 50%), 30.0 parts by weight of xylene, 30.0 parts by weight of methyl isobutyl ketone and 10.0 parts by weight of an isocyanate-based hardener to obtain an oil-based spray cosmetic for reversible thermochromic false nail.

[0199] The foregoing oil-based spray cosmetic for reversible thermochromic false nail was sprayed onto the surface of a false nail made of acetyl cellulose resin through a spray gun having an aperture diameter of 0.6 mm, and then dried to form a reversible thermochromic layer thereon. Onto the reversible thermochromic layer was then sprayed a top coating cosmetic obtained by uniformly stirring 1.5 parts by weight of a metallic luster pigment (trade name: Iriodin 219, produced by Merck Japan Ltd.) in a vehicle consisting of 50.0 parts by weight of an acrylic resin solution (solid content: 50%; xylene: 50%), 45 parts by weight of cyclohexanone, 3.0 parts by weight of a leveling agent, 1.0 part by weight of an anti-foaming agent and 1.0 part by weight of a viscosity modifier to form a layer containing a light stabilizer and a noble metal luster pigment. Thus, a reversible thermochromic false nail was obtained.

[0200] The foregoing false nail became colorless when heated to a temperature of not lower than 32° C. but assumed metallic pink at a temperature of not higher than 15° C.

[0201] The foregoing false nail exhibited an improved light-fastness and an excellent discoloration sensitivity similarly to the light-fastness test specimen 21

EXAMPLE 22

[0202] Molding Resin Composition Containing Reversible Thermochromic Composition 2 and Molded Product Comprising Same

[0203] 40.0 parts by weight of a microcapsuled pigment comprising the reversible thermochromic composition 2 incorporated therein were blended with 1,000.0 parts by weight of a low density polyethylene resin (melt flow rate: 1.3) and 0.5 parts by weight of a metallic soap-based lubricant. The mixture was then subjected to uniform dispersion by a tumbler mixer to obtain a molding resin composition. The molding resin composition thus obtained was then processed through a extruder at a cylinder temperature of 170° C. and a forward end die temperature of 180° C. to obtain a reversible thermochromic polyethylene resin pellet.

[0204] The foregoing molding resin composition was then blow-molded in a goldfish molded at a cylinder temperature of 160° C. to obtain a goldfish-shaped reversible thermochromic hollow molded product.

[0205] The foregoing molded product assumed white when heated to a temperature of 32° C. but assumed pink at a temperature of not higher than 15° C.

[0206] The foregoing molded product exhibited an improved light-fastness and an excellent discoloration sensitivity similarly to the light-fastness test specimen 2.

EXAMPLE 23

[0207] Molding Resin Composition Containing Reversible Thermochromic Composition 13 and Filament Comprising Same

[0208] 50.0 parts by weight of a microcapsuled pigment comprising the reversible thermochromic composition 13 incorporated therein were blended with 1,000.0 parts by weight of nylon 12 resin (melting point: 178° C.). The mixture was then subjected to uniform dispersion by a Henschel mixer to obtain a molding resin composition. The molding resin composition was then processed through an extruder at a cylinder temperature of 190° C. and a forward end die temperature of 200° C. to obtain a reversible thermochromic nylon 12 resin pellet.

[0209] The foregoing molding resin composition was then melt-spun at a cylinder temperature of 190° C. and a die temperature of 200° C. to obtain a reversible thermochromic filament.

[0210] The filament was then planted on the head of a doll.

[0211] The foregoing filament became colorless when heated to a temperature of not lower than 32° C. but assumed pink at a temperature of not higher than 15° C.

[0212] The foregoing filament exhibited an improved light-fastness and an excellent discoloration sensitivity similarly to the light-fastness test specimen 13.

EXAMPLE 24

[0213] Molding Resin Composition Containing Reversible Thermochromic Composition 13 and Composite Filament Comprising Same

[0214] 5 parts by weight of a microcapsuled pigment comprising the reversible thermochromic composition 13 incorporated therein, 1 part by weight of a dispersant and 94 parts by weight of nylon 12 resin having a melting point of 180° C. were melt-kneaded through an extruder at a temperature of 200° C. to obtain a core-forming reversible thermochromic nylon 12 resin pellet.

[0215] Separately, 95 parts by weight of nylon 12 resin having a melting point of 180° C. and 5.0 parts by weight of 2-(3,5-di-t-amyl-2-hydroxyphenyl)benzotriazole as a light stabilizer were melt-kneaded through an extruder to obtain a sheath-forming nylon 12 resin pellet.

[0216] The foregoing reversible thermochromic nylon 12 resin pellet was supplied into a core forming extruder while the sheath-forming nylon 12 resin pellet was supplied into a sheath forming extruder. The two resin pellets were each extruded at a melting temperature of 200° C. and then spun through 18 ejection holes from a composite fiber spinning machine. The thread thus spun was then wound at a draw ratio of 3 to obtain a reversible thermochromic filament with 1,260 denier consisting of 18 filaments.

[0217] The foregoing composite filament became colorless when heated to a temperature of not lower than 32° C. but assumed pink at a temperature of not higher than 15° C.

[0218] The foregoing composite filament exhibited an improved light-fastness and an excellent discoloration sensitivity similarly to the light-fastness test specimen 13.

[0219] The discoloration temperature of the reversible thermochromic composition of the invention and products comprising same can be freely adjusted even the kind of the electron donating compound and electron accepting compound to be used in combination remain the same. Accordingly, the reversible thermochromic composition of the invention exhibits an remarkably improved light-fastness, particularly during quenching, and better discoloration sensitivity.

[0220] While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.

[0221] This application is based on Japanese patent application No. 2000-275649 filed on Aug. 9, 2000, the entire contents thereof being hereby incorporated by reference.

Claims

1. A reversible thermochromic composition having an improved light-fastness, which comprises (a) an electron donating compound, (b) an electron accepting compound having ultraviolet absorbing capacity which is represented by the following general formula I: 9 wherein X represents a hydrogen atom, —CnH2n+1 or —OCmH2m+1; m represents an integer of from 1 to 9; n represents an integer of from 1 to 10; and p represents an integer of from 1 to 3, and (c) a discoloration temperature adjustor.

2. A reversible thermochromic composition having an improved light-fastness, which comprises (a) an electron donating compound, (b) an electron accepting compound having ultraviolet absorbing capacity which is represented by the following general formula I: 10 wherein X represents a hydrogen atom, —CnH2n+1 or —OCmH2m+1; m represents an integer of from 1 to 9; n represents an integer of from 1 to 10; and p represents an integer of from 1 to 3, (c) a discoloration temperature adjustor, and (d) an electron accepting light-fastness providing agent represented by the following general formula II: 11 wherein n represents an integer of from 5 to 17 (straight-chain and branched); X represents a C1-C4 straight-chain or branched hydrocarbon or halogen; Y represents a C1-C4 straight-chain or branched hydrocarbon or halogen; p represents an integer of from 0 to 3; and m represents an integer of from 0 to 3.

3. A reversible thermochromic composition having an improved light-fastness, which comprises (a) an electron donating compound, (b) an electron accepting compound having ultraviolet absorbing capacity represented by the following general formula I: 12 wherein X represents a hydrogen atom, —CnH2n+1 or —OCmH2m+1; m represents an integer of from 1 to 9; n represents an integer of from 1 to 10; and p represents an integer of from 1 to 3, (c) a discoloration temperature adjustor, (d) an electron accepting light-fastness providing agent represented by the following general formula II: 13 wherein n represents an integer of from 5 to 17 (straight-chain and branched); X represents a C1-C4 straight-chain or branched hydrocarbon or halogen; Y represents a C1-C4 straight-chain or branched hydrocarbon or halogen; p represents an integer of from 0 to 3; and m represents an integer of from 0 to 3, and (e) a light stabilizer.

4. The reversible thermochromic composition having an improved light-fastness according to any one of claims 1 to 3, which further comprises a microcapsule incorporating said reversible thermochromic composition therein.

5. The reversible thermochromic composition having an improved light-fastness according to any one of claims 1 to 3, which further comprises a color developer blended in said reversible thermochromic composition having an improved light-fastness.

6. The reversible thermochromic composition having an improved light-fastness according to claim 5, wherein said color developer is a binder.

7. A molding resin composition comprising a synthetic resin and a reversible thermochromic composition according to any one of claims 1 to 3 blended therein.

8. A reversible thermochromic yarn comprising a reversible thermochromic composition according to any one of claims 1 to 3 and a thermoplastic resin.

9. A reversible thermochromic layer having an improved light-fastness according to any one of claims 1 to 3, which further comprises (f) a layer of light stabilizer and/or metallic luster pigment provided on the surface of a layer formed by a reversible thermochromic composition.