JPH06106848A - Reversible thermochromism material - Google Patents

Abstract

PURPOSE:To manufacture a reversible thermochromism material provide with high coloring density and discoloration sensitivity by forming a heat-sensitive color developing layer containing a specified fluoran compound, an electron- accepting developer and s coloring control agent on a substrate. CONSTITUTION:The given quantities of a fluoran compound, an electron accepting compound such as nonylphenol and a coloring control agent such as an alcohol group expressed by the formula (where R1 and R2 represent 1-5C alkyl and R3 represents 1-4C alkyl.) are respectively heated to prepare a uniform solution. The uniform solution is applied to a substrate such as paper or a plastic film for coating and dried thereon to form a heat-sensitive color developing layer and manufacture a reversible thermochromism material. As the fluoran (electron donor coloring agent) expressed by the formula, (N-methyl-N-phenyl) amino-6-dimethylaminofluoran, 2-(N-methyl-phenyl) amino-6-6-di-n- dimethylaminofluoran or the like is available.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible thermochromic material which changes its color sharply and reversibly in response to temperature changes.

[0002]

2. Description of the Related Art Conventionally, electron-donating color formers (hereinafter referred to as color formers) and electron-accepting color formers (hereinafter referred to as color formers).
A reversible thermochromic material that essentially contains the three components of a color-developing agent and a color-developing agent is disclosed in, for example, Japanese Patent Publication No. 51-44706, and is already well known. Such a reversible thermochromic material is used for food and drink related to freezing, refrigeration and heating, stationery such as writing utensils and postcards, and decoration for clothes, toys, wallpaper and the like.

A reversible thermochromic material is required to have a high color density, a stable color image, and good color-changing sensitivity, that is, to be sensitive in color development and decolorization in response to temperature changes. However, it is necessary to use a color former suitable for these purposes. As a color former that develops a greenish color, fluoran of the following formula (1) is disclosed in JP-A-51-44706, and JP-B-61-47879.
In the publication, the fluoran of formula (2) is used.

[0004]

[Chemical 2]

[0005]

[Chemical 3]

However, the reversible thermochromic materials using fluorane of the formulas (1) and (2) both have insufficient coloring density and low discoloration sensitivity.

[0007]

Therefore, the present invention aims to provide a reversible thermochromic material satisfying the above-mentioned required characteristics, that is, a reversible thermochromic material having a high color density and high discoloration sensitivity. To aim.

[0008]

A reversible thermochromic material according to the present invention is a reversible thermochromic material which essentially comprises three components: an electron-donating color former, an electron-accepting developer and a color-controlling agent. As the donative color former, a compound represented by the general formula (I)

[0009]

[Chemical 4]

(In the formula, R ₁ and R ₂ each independently represent an alkyl group having 1 to 5 carbon atoms, and R ₃ represents an alkyl group having 1 to 4 carbon atoms). It is characterized by containing at least one kind. In the general formula (I), R ₁ and R ₂ are each independently
Examples thereof include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, and the like.
R ₃ is a methyl group, an ethyl group, an n-propyl group, n
A butyl group and the like can be mentioned, but a methyl group or an ethyl group is particularly preferable.

Specific examples of the fluorane compound represented by the general formula (I) used in the present invention are shown below. (1) 2- (N-methyl-N-phenyl) amino-6-
Dimethylaminofluorane (2) 2- (N-methyl-N-phenyl) amino-6-
Diethylaminofluorane (3) 2- (N-methyl-N-phenyl) amino-6-
Di-n-propylaminofluorane (4) 2- (N-methyl-N-phenyl) amino-6-
Di-n-butylaminofluorane (5) 2- (N-methyl-N-phenyl) amino-6-
Di-n-pentylaminofluorane (6) 2- (N-methyl-N-phenyl) amino-6-
(N-Methyl-N-ethyl) aminofluorane (7) 2- (N-methyl-N-phenyl) amino-6-
(N-Ethyl-Nn-propyl) aminofluorane (8) 2- (N-methyl-N-phenyl) amino-6-
(N-Methyl-Nn-butyl) aminofluorane (9) 2- (N-methyl-N-phenyl) amino-6-
(N-Ethyl-Nn-butyl) aminofluorane (10) 2- (N-methyl-N-phenyl) amino-6
-(N-n-propyl-N-n-butyl) aminofluorane (11) 2- (N-methyl-N-phenyl) amino-6
-(N-Methyl-N-n-pentyl) aminofluorane (12) 2- (N-methyl-N-phenyl) amino-6
-(N-Ethyl-N-n-pentyl) aminofluorane (13) 2- (N-methyl-N-phenyl) amino-6
-(Nn-propyl-Nn-pentyl) aminofluorane (14) 2- (N-methyl-N-phenyl) amino-6
-(Nn-butyl-Nn-pentyl) aminofluorane (15) 2- (N-ethyl-N-phenyl) amino-6
-Dimethylaminofluorane (16) 2- (N-ethyl-N-phenyl) amino-6
-Diethylaminofluorane (17) 2- (N-ethyl-N-phenyl) amino-6
-Di-n-propylaminofluorane (18) 2- (N-ethyl-N-phenyl) amino-6
-Di-n-butylaminofluorane (19) 2- (N-ethyl-N-phenyl) amino-6
-Di-n-pentylaminofluorane (20) 2- (Nn-propyl-N-phenyl) amino-6-dimethylaminofluorane (21) 2- (Nn-propyl-N-phenyl) amino -6-Diethylaminofluorane (22) 2- (Nn-propyl-N-phenyl) amino-6-di-n-propylaminofluorane (23) 2- (Nn-butyl-N-phenyl) Amino-6-dimethylaminofluorane (24) 2- (Nn-butyl-N-phenyl) amino-6-diethylaminofluorane (25) 2- (Nn-butyl-N-phenyl) amino-6 -Di-n-propylaminofluorane The fluorane compound represented by the general formula (I) used in the present invention can be produced, for example, by a known production method represented by the following reaction formula, that is, by the general formula (II A diphenylamine compound represented by in represented by a benzophenone compound of the general formula (III) are reacted in the presence of sulfuric acid, it can then be obtained cowpea to alkali treatment.

[0012]

[Chemical 5]

(In the formula, R ₁ , R ₂ and R ₃ are the same as described above.) The reversible thermochromic material according to the present invention is disclosed in, for example, Japanese Patent Publication No. 51-44706. Can be manufactured by various methods. In general,
It is manufactured by mixing a color former, a color developer and a color control agent and heating the mixture to form a uniform solution. Further, if necessary, the mixture of each component may be encapsulated in microcapsules, kneaded in a resin, or dissolved or dispersed in a vehicle to be used for various purposes. If necessary, a fourth component may be added to the above components in order to change or adjust the properties of the reversible thermochromic material.

As for the mode of its use, the reversible thermochromic material according to the present invention is a microencapsulated material as described above, or the reversible thermochromic material is a solid solution of a non-thermoplastic resin. Granules are coated with a hydrophilic polymer to form a composition, which is used as a printing ink,
It may be used as a paint or spray ink by coating it on a substrate such as paper, plastic, glass, ceramics, metal, etc.
Alternatively, it can be used for various purposes as a molded body or a fiber film kneaded in a polymer, or by being bound to various fibers.

In such a reversible thermochromic material, the composition ratio of coloring agent: developing agent: color control agent is usually a weight ratio,
It is 1: 0.1 to 50: 1 to 800. Further, if necessary, in addition to the above components, a dye, a pigment, an antioxidant, an ultraviolet absorber, an infrared absorber, a solubilizing agent, within the range that does not impair the color changing performance of the reversible thermochromic material according to the present invention. It is also possible to add a diluent, a sensitizer, an adhesive or the like. Furthermore,
A protective layer such as a polyethylene film may be provided on the reversible thermochromic material, if necessary.

In the present invention, a leuco dye other than the compound represented by the general formula (I) may be used in combination as a color former for the purpose of toning. Examples of the color developer used for the reversible thermochromic material include compounds having a phenolic hydroxyl group, for example, tert. -Butylphenol, nonylphenol, dodecylphenol, styrenated phenol, 2,2-methylenebis (4-methyl-6-tert.
-Butylphenol), α-naphthol, β-naphthol, 1,2-dioxynaphthalene, hydroquinone monomethyl ether, methyl gallate, ethyl gallate, propyl gallate, butyl gallate, hexyl gallate, octyl gallate, gallic acid. Dodecyl, cetyl gallate,
Stearyl gallate, methyl p-oxybenzoate, p-
Ethyl oxybenzoate, propyl p-oxybenzoate,
butyl p-oxybenzoate, octyl p-oxybenzoate, dodecyl p-oxybenzoate, bisphenol A,
Bisphenol S, isopropyl catechol, ter
t. -Butylcatechol, pyrocatechol, resorcin, hydroquinone, chlorophenol, bromophenol, phenylphenol, trichlorophenol, 2
-Oxy-1-naphthoic acid, 2-oxy-p-toluic acid, salicylic acid, m-oxybenzoic acid, p-oxyphthalic acid, methyl protocatechuate, ethyl protocatechuate, propyl protocatechuate, octyl protocatechuate, 2,4, Examples thereof include 6-trioxymethylbenzene, 2,3,4-trioxyethylbenzene, 2,3,5-trioxynaphthalene, tannic acid and phenol resin.

As the metal salt of the compound having a phenolic hydroxyl group, for example, sodium, potassium, lithium, calcium of the compound having a phenolic hydroxyl group,
Examples thereof include metal salts of metals such as zinc, aluminum, magnesium, nickel, cobalt, tin, lead, iron, vanadium and titanium. As carboxylic acids, maleic acid, fumaric acid, benzoic acid, toluic acid, p-ter
t. -Butylbenzoic acid, chlorobenzoic acid, bromobenzoic acid, naphthoic acid, phthalic acid, naphthalenedicarboxylic acid,
Examples thereof include acetic acid, propionic acid and butyric acid. Examples of metal salts of carboxylic acids include metal salts of metals such as sodium, potassium, lithium, calcium, zinc, aluminum, magnesium, nickel, cobalt, tin, lead, iron, vanadium, and titanium of the carboxylic acids. be able to.

Examples of the acidic phosphates include butyl acid phosphate, 2-ethylhexyl acid phosphate, dodecyl acid phosphate, stearyl acid phosphate, phenyl acid phosphate, tolyl acid phosphate, dibutyl phosphite, dioctyl phosphite, didodecyl phosphite. , Diphenyl phosphite, ditolyl phosphite and the like. Further, as the metal salt of the acidic phosphoric acid ester, mention may be made of metal salts of the acidic phosphoric acid ester such as sodium, potassium, zinc, aluminum, magnesium, nickel, cobalt, tin, lead, iron, vanadium and titanium. You can

Examples of the sulfonic acid include octylsulfonic acid, dodecylsulfonic acid, aminoethanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, xylenesulfonic acid, propylbenzenesulfonic acid, nitrobenzenesulfonic acid, aminobenzenesulfonic acid, sulfanilic acid. , Sulfobenzoic acid, phenolsulfonic acid, benzylsulfonic acid, diphenylmethanesulfonic acid, naphthalenesulfonic acid, naphtholsulfonic acid, carboxynaphthalenesulfonic acid, anthraquinonesulfonic acid, oxyanthraquinonesulfonic acid, aminoanthraquinonesulfonic acid, chloranthraquinonesulfonic acid, etc. Can be mentioned. In addition, as metal salts of sulfonic acids,
Sodium, potassium, zinc, aluminum, magnesium, nickel, cobalt, tin of the sulfonic acid,
Mention may be made of metal salts of metals such as lead, iron, vanadium and titanium.

As the triazole compound, 1,2,3-triazole, 4 (5) -hydroxy-1,2,3-triazole,
5 (6) -methyl-1,2,3-benzotriazole, 5-chloro-1,2,3-benzotriazole, 7-nitro-1,2,3
-Benzotriazole, 4-benzoylamino-1,2,3
-Benzotriazole, 4-hydroxy-1,2,3-benzotriazole, naphtho-1,2,3-triazole, 5,5 '
-Bis (1,2,3-benzotriazole) and the like can be mentioned.

As halohydrin and its derivatives, 2,2,
2-trichloroethanol, 2,2,2-tribromoethanol, 2,2,2-trifluoroethanol, 1,1,1-trichloro-2-methyl-2-propanol, 4,4,4-tribromobutanol , 1,3-dibromo-2-propanol, 1,3-dichloro-2-propanol, 2,2-bis (bromomethyl) -3-bromo-1-propanol, 2,
2-bis (chloromethyl) -3-chloro-1-propanol, 2,2-bis (chloromethyl) -1,3-propanediol, N-phenyl-N '-(1-hydroxy-2,2,2
-Trichloroethyl) thiourea, N- (1-hydroxy-2,2,2-trichloroethyl) thiobenzamide, 3-
(N-1-hydroxy-2,2,2-trichloroethyl) aminopyridine, 2- (1'-hydroxy-2 ', 2', 2'-trichloroethyl) furan and the like can be mentioned. In the present invention, among the above, a compound having a phenolic hydroxyl group, particularly bisphenol A, is preferably used.

The color-developing agent controls the color-developing reaction between the color-developing agent and the color-developing agent, and its action governs the change in the compatibility or the reactivity with the temperature of each component mixture. It is considered to reversibly control the color-forming reaction between the color-developing agent and the color-developing agent within a specific temperature range. In the reversible thermochromic material, the color change temperature can be determined by the type or blending amount of the color control agent.

Alcohols such as n-octyl alcohol, n-nonyl alcohol,
n-decyl alcohol, n-lauryl alcohol, n-
Myristyl alcohol, n-cetyl alcohol, n-stearyl alcohol, n-icosyl alcohol, n-
Docosyl alcohol, n-melisyl alcohol, isocetyl alcohol, isostearyl alcohol, isodocosyl alcohol, oleyl alcohol, cyclohexanol, cyclopentanol, benzyl alcohol, cinnamyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene Glycol, cyclohexane-1,4-diol, 1,2,6-hexanetriol, pentaerythritol, sorbit,
Examples include annit.

Examples of the esters include amyl acetate, octyl acetate, butyl propionate, octyl propionate, phenyl propionate, ethyl caproate, amyl caproate, ethyl caprylate, amyl caprylate, amyl caprate, octyl caprate, and laurin. Butyl acid salt, dodecyl laurate, stearyl laurate, butyl myristate, hexyl myristate, ethyl palmitate, octyl palmitate, lauryl palmitate, butyl stearate, hexyl stearate, lauryl stearate, cetyl stearate, butyl behenate. ,
Lauryl behenate, ethyl benzoate, butyl benzoate, amyl benzoate, phenyl benzoate, ethyl acetoacetate, butyl oleate, butyl acrylate, dibutyl oxalate, dibutyl malonate, dibutyl sebacate, dimethyl phthalate, etc. be able to.

Examples of ethers include diethylene glycol dimethyl ether, diphenyl ether, distearyl ether, hexyl ether, diisopropylbenzyl ether, dioxane, diethylene glycol dibutyl ether, ethylene glycol diethyl ether and ethylene glycol diphenyl ether.

Examples of the ketones include diphenyl ketone, distyryl ketone, methylhexyl ketone, cyclohexanone, acetophenone, propiophenone, benzophenone, 2,4-pentanedione, dimyristyl ketone, and ketone wax. As carboxylic acids, lauric acid, myristic acid, palmitic acid, adipic acid, benzoic acid, p-tert. -Butylbenzoic acid may be mentioned. Examples of acid amides include capric acid amide, caprylic acid amide, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and oleic acid amide.

Examples of aliphatic hydrocarbons include decane, dodecane, undecane, etc., aromatic hydrocarbons such as naphthalene, anthracene, diphenolmethane, etc., and alicyclic hydrocarbons such as decalin, pinene, bicyclohexyl, etc. In addition to these, light oil, kerosene and the like can be used. In the present invention, among the above, alcohols or esters are particularly preferably used.

In the reversible thermochromic material according to the present invention,
The color-developing agent, the color-developing agent and the color-developing control agent are each 1 type or 2 types.
You may use it in combination of 2 or more types. Each of these components may be uniformly mixed and applied to each application as it is, or may be applied by the following method according to the purpose. (1) A mixture of each component is encapsulated in microcapsules by a known method. (2) A mixture of each component or a microencapsulated product of such a mixture is dissolved or dispersed in a vehicle. (3) The microencapsulated product of each component or mixture of each component is uniformly kneaded into the resin. (4) Each component is made into a solid solution of a non-thermoplastic resin, and the particles of this solid solution are further coated with a hydrophilic polymer compound film. (5) Encapsulate the mixture of each component in microcapsules,
Further, its surface is coated with a hydrophilic polymer compound. (6) A mixture of the respective components, a microencapsulated product of the mixture, or a hydrophilic polymer compound coating of the microencapsulated product of such a mixture is bound to the surface of the fiber using a binder.

[0029]

The present invention will be described below with reference to examples.
The present invention is not limited to these examples. Example 1 2 g of 2- (N-methyl-N-phenyl) amino-6-diethylaminofluorane, 3 g of bisphenol A and 45 g of stearyl alcohol were melt mixed and kept at 80 ° C. On the other hand, 10 g of a 20% aqueous solution of a system modifier (Emulsifier SM-200 consisting of anionic oligomer manufactured by Mitsui Toatsu Chemicals, Inc.) and 70 g of water were mixed, and the pH was adjusted to 4 with a 20% caustic soda aqueous solution. Heated. The above solution was added to this with stirring with a homomixer, and the mixture was stirred at the same temperature at a rotation speed of 8000 rpm for 30 minutes.

Then, 80 of melamine-formaldehyde prepolymer (UMC-300 manufactured by Mitsui Toatsu Chemicals, Inc.) was used.
% Aqueous solution (20 g) and water (10 g) are gradually added, and the number of revolutions is 4000 r at the same temperature until the average particle diameter becomes 7 to 8 μm.
Stirred at pm. The stirring was changed from a homomixer to an agitator, the internal temperature was lowered to 15 ° C., and 25% ammonia water was added to p.
After adjusting to H7.5, the mixture was stirred at the same temperature for 30 minutes to obtain a microcapsule dispersion liquid.

Next, 20 g of this microcapsule dispersion liquid
And 10% polyvinyl alcohol aqueous solution 4g are mixed,
A reversible thermochromic sheet was prepared by coating the coated paper so that the solid coating amount was 10 g / m ² and drying. This reversible thermochromic sheet exhibited a deep green color at room temperature. When this sheet was heated at a rate of 1 ° C./min, it began to lose color at 52.8 ° C. and completely disappeared at 53.5 ° C. Next, when the decolorized sheet was cooled at a rate of 1 ° C./min, it started to develop color at 52.5 ° C. and completely developed at 51.5 ° C.

Example 2 2- (N-methyl-N-phenyl) amino-6-di-n
-Butylaminofluorane 2g, Bisphenol A 3g
And 45 g of myristyl alcohol are melt mixed, and 80 ° C
I kept it warm. On the other hand, the same system modifier (SM-20
20 g of a 20% aqueous solution of 0) and 70 g of water are mixed,
The pH was adjusted to 4 with an aqueous solution of caustic soda, and then heated to 80 ° C. The above solution was added to this with stirring with a homomixer, and the mixture was stirred at the same temperature at a rotation speed of 8000 rpm for 30 minutes.

Then, an 80% aqueous solution of the same melamine-formaldehyde prepolymer (UMC-300) as described above 2
After gradually adding 0 g and 10 g of water, the average particle size is 7 to 8
The mixture was stirred at the same temperature at a rotation speed of 4000 rpm until the particle diameter became μm. The stirring was changed from a homomixer to an agitator, the internal temperature was lowered to 15 ° C., the pH was adjusted to 7.5 with 25% aqueous ammonia, and the mixture was stirred at the same temperature for 30 minutes to obtain a microcapsule dispersion liquid.

20 g and 10 of this microcapsule dispersion liquid
% Polyvinyl alcohol aqueous solution was mixed, coated on a coated paper so that the solid content was 10 g / m ^2, and dried to prepare a reversible thermochromic sheet. This reversible thermochromic sheet exhibited a deep green color at room temperature. When this sheet was heated at a rate of 1 ° C./minute, it began to decolor at 35.8 ° C. and completely decolored at 36.0 ° C. Next, when the decolorized sheet was cooled at a rate of 1 ° C./minute, it started to develop color at 33.8 ° C. and completely developed at 33.3 ° C.

Comparative Example 1 2- (N-methyl-N-) which is the color former in Example 2
Examples except that 2-dibenzylamino-4-methyl-6-diethylaminofluorane (compound of formula (1) above) was used instead of 2 g of phenyl) amino-6-di-n-butylaminofluorane. The same operation as in 2 was carried out to produce a reversible thermochromic sheet. This reversible thermochromic sheet exhibited a medium density green at room temperature. When this sheet was heated at a rate of 1 ° C./min, the color began to disappear at 35.3 ° C. and completely disappeared at 35.9 ° C. Next, when the decolorized sheet was cooled at a rate of 1 ° C./minute, it started to develop color at 33.5 ° C. and completely developed at 31.5 ° C.

Comparative Example 2 2- (N-methyl-N-) which is the color former in Example 2
Phenyl) amino-6-di-n-butylaminofluorane 2 g, instead of 2- (N-methyl-N-phenyl)
A reversible thermochromic sheet was obtained by performing the same operation as in Example 2 except that amino-6- (N-ethyl-N-p-toluyl) aminofluorane (the compound of the formula (2)) was used. It was made. This reversible thermochromic sheet exhibited a medium density green at room temperature. When this sheet was heated at a rate of 1 ° C./minute, it began to decolor at 35.2 ° C. and completely decolored at 35.8 ° C. Next, when the decolorized sheet was cooled at a rate of 1 ° C./minute, it started to develop color at 34.0 ° C. and completely developed at 30.8 ° C.

Table 1 below shows a performance comparison between the reversible thermochromic sheets prepared in Examples 1 and 2 and Comparative Examples 1 and 2. In the table, the color density is as follows: ◯: rich green color, ×: medium green color. In addition, the color development sensitivity is represented by the following formula. Therefore, the smaller this number is,
It shows that the color development sensitivity is high. Color development sensitivity = Color development start temperature-
Color development completion temperature

[0038]

[Table 1]

As is clear from Table 1, the reversible thermochromic material according to the present invention has a high coloring density and an excellent coloring sensitivity.

[0040]

INDUSTRIAL APPLICABILITY As described above, the reversible thermochromic material according to the present invention exhibits a high coloring density and high discoloration sensitivity.

Claims (2)

[Claims] 1. A reversible thermochromic material which essentially comprises three components: an electron-donating color former, an electron-accepting color developer, and a color-controlling agent. ] (In the formula, R ₁ and R ₂ each independently represent an alkyl group having 1 to 5 carbon atoms, and R ₃ represents an alkyl group having 1 to 4 carbon atoms.) A reversible thermochromic material characterized by containing. 2. The reversible thermochromic material according to claim 1, which is encapsulated in microcapsules.