JPH0740660A - Reversible, color-variable, temperature-sensitive recording composition - Google Patents

Abstract

PURPOSE:To provide a composition with excellent data recording properties which can very easily repeat holding and erasing of records by controlling the histeresis when the temperature is raised or decreased, and easily set a large hysteresis width (temperature region necessary to hold records), and freely adjust the hysteresis width. CONSTITUTION:The reversible color-variable temperature-sensitive recording composition comprises (a) a colorless or pole-color leuco dye, (b) a developer substance capable of letting the leuco dye generate color, and (c) an ester compound having at least four ester bonds in a molecule and 3000 or smaller molecular weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible color-changing thermosensitive recording composition, and more specifically, it only controls the history of temperature increase or decrease, and exhibits two or more different types within a certain temperature range. The present invention relates to a reversible color-changing thermosensitive recording composition which can be used for recording information capable of exhibiting a color state.

[0002]

2. Description of the Related Art It has been attempted for a long time to use various kinds of recording materials by combining a colorless or light-colored leuco dye with a color-developing substance that develops the leuco dye. Since it does not require a special device, it is widely used for pressure-sensitive copying paper, heat-sensitive recording paper and the like (for example, USP 2,548,364 and 2,71).
No. 1,375, No. 2,730,456, No. 2,800,457, No. 3,244,549, Japanese Patent Publication No. 40-9310, No. 42-20144.
No. 43-4160, No. 45-14039
No.

On the other hand, it has been found that when a certain kind of organic solvent is further applied to the combination of compounds of this kind, the coloration phenomenon reversibly changes with temperature (USP 3,5).
No. 60,229), a so-called leuco-based thermochromic composition has been put to practical use for various purposes (Japanese Patent Publication No. 62-62).
No. 28990).

[0004]

However, the above-mentioned pressure-sensitive copying paper and heat-sensitive recording paper are used only for one-time recording operation and cannot be repeatedly used repeatedly. In recent years, when resource problems have been raised, its use is inefficient.

On the other hand, various thermochromic compositions derived from these techniques and put into practical use are expected to have some repetitive utility in view of the reversible change in coloration state. However, once recorded information is easily lost due to temperature change, it is not satisfactory in terms of record retention.

In recent years, 2 consisting of a leuco dye and a color-developing substance
The composition in which a carrier compound selected from alcohols, esters, ketones and the like is mixed in the component system, the coloration phenomenon reversibly changes with temperature, and the information recorded by keeping it within a predetermined temperature range. It has been reported that the above can be maintained (JP-A-59-120492, JP-A-60-264285, etc.). However, it cannot be said that the composition has a sufficiently wide hysteresis width (a temperature range necessary to retain the record) to the extent that (i) the record retention is completely guaranteed, and (ii) Further, the hysteresis width itself depends on the inherent properties of the carrier compound used, and it is difficult to find a substance exhibiting an appropriate hysteresis width. Therefore, the hysteresis width cannot be freely adjusted, and Under the present circumstances, there is a drawback that the discoloring behavior due to temperature change does not become sharp when adjusted by additionally compounding other additives.

The present invention has been made in view of such a situation, and its main purpose is to extremely easily hold and erase a record by controlling a history state of temperature increase or temperature decrease. And a wide hysteresis width (a temperature range necessary for holding a record) can be easily set, and the hysteresis width can be freely adjusted to provide a composition excellent in information recording property. Especially.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to solve the above-mentioned problems, and as a result, in addition to a leuco dye and a color-developing substance, at least four ester bonds are present in the molecule. It has been found that the above object can be achieved by using a specific ester compound having the above, and the present invention has been completed here.

That is, the present invention provides (a) a colorless or light-colored leuco dye, (b) a color-developing substance having the ability to develop the color of the leuco dye, and (c) at least four ester bonds in the molecule. And a reversible color-changing thermosensitive recording composition comprising an ester compound having a molecular weight of 3000 or less.

In the present invention, as the colorless or light-colored leuco dye, any of those commonly known as a dye for pressure-sensitive copying paper, a dye for thermal recording paper, etc. can be used. Do system, Fluoran system,
Any known phenothiazine-based, indolylphthalide-based, leucoauramine-based, spiropyran-based, rhodamine lactam-based, triphenylmethane-based, triazene-based, spirophthalanexanthene-based, naphtholactam-based, azomethine-based, etc. You may use the thing. Specific examples of such leuco dyes include 3,6-dimethoxyfluorane, 3,6-dibutoxyfluorane, 3-diethylamino-6,8-dimethylfluorane, and 3-chloro-6-phenylaminofluorane. , 3-diethylamino-6-methyl-7-chlorofluorane, 3-diethylamino-7,8-benzofluorane, 3,3-bis (p
-Dimethylaminophenyl) -6-dimethylaminophthalide, 3,3'-bis (p-dimethylaminophenyl)
Phthalide, 3-diethylamino-7-phenylaminofluorane, 3,3-bis (p-diethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylaminophenyl) -3- (1-ethyl-2- Methylindol-3-yl) phthalide, 3- (4-diethylamino-2-methyl) phenyl-3- (1,2-dimethylindol-3-yl) phthalide, 2 '-(2-chloroanilino) -6'- Dibutylamino spiro [phthalide-
3,9′-xanthene] and the like, but the present invention is not limited thereto. In the present invention, these leuco dyes can be used alone or in combination of two or more, and by this combination, colors at the time of color development are yellow, orange, red, peach, magenta, purple, blue, blue-green, Green,
It can be any color such as brown or black.

As the color-developing substance having the ability to develop the color of the leuco dye contained in the composition of the present invention, an organic color-developing substance usually used as a color-developing agent for pressure-sensitive copying paper, heat-sensitive recording paper and the like is used. Either can be used. Specific examples of such a color-developing substance include 1,2-butylbenzotriazole and bisbenzotriazole-5-methane.
3-benzotriazoles, phenol, nonylphenol, bisphenol A, bisphenol F, 2,2 '
-Phenols such as biphenol, β-naphthol, 1,5-dihydroxynaphthalene, paraoxybenzoic acid ester and gallic acid ester, p-phenylphenol-
Phenol resin oligomers such as formalin resin and p-butylphenol-acetylene resin, aliphatic carboxylic acids such as oxalic acid, tartaric acid, citric acid, succinic acid and stearic acid, and aromatic compounds such as benzoic acid, gallic acid, salicylic acid and naphthoic acid. Examples thereof include acidic phosphoric acid esters such as carboxylic acids, benzyl acid phosphate, methyl acid phosphate, and dilauryl phosphate. Further, various organic color-developing substances described above and zinc, magnesium, aluminum, calcium, and titanium. Metal salts with manganese, tin, nickel, sodium, potassium, lithium, copper, iron, lead and the like can be used, but are not limited to these.

In the present invention, by using one kind or a combination of two or more kinds of these color-developing substances, the color density at the time of color development can be freely adjusted. Therefore, the amount to be used may be arbitrarily selected according to the desired color density and is not particularly limited, but is usually about 0.1 to 100 parts by weight with respect to 1 part by weight of the leuco dye described above. It is preferable to select within the range.

In the present invention, in addition to the leuco dye and the color-developing substance described above, it is necessary to use an ester compound having at least 4 ester bonds in the molecule and having a molecular weight of 3000 or less. By using such a compound, the coloration state of the leuco dye reversibly changes according to the temperature change, and further, the discoloration temperature is deviated between the temperature rising and the temperature lowering. Hereinafter, with reference to FIG. 1, a temperature change in such a characteristic coloration state that occurs in the present invention will be described in detail.

FIG. 1 is a graph showing the relationship between temperature and color density of the composition of the present invention. First, the composition of the present invention,
In FIG. 1, when the temperature is an arbitrary temperature T ₁ within a temperature range showing the highest color density C ₂ (hereinafter, simply referred to as a color-developing state), when the temperature is raised, the color develops at the time when the temperature reaches the temperature T _3. When the temperature starts to decrease sharply and reaches the temperature T ₃ ′, the minimum color density C ₁ (hereinafter, simply referred to as a decolored state) is exhibited. Next, when the temperature of the composition of the present invention at an arbitrary temperature T ₄ in the temperature range showing the decolored state is lowered,
Even when the temperatures T _{3 ′} and T ₃ described above are reached, the color is still in the decolored state, the temperature is further lowered, and when the temperature reaches the temperature T ₂ , the color density starts to increase rapidly, and the temperature T _{2 When} it reaches _′ , the state returns to the coloring state C ₂ . Such a reversible color change cycle, which is sometimes called a quasi-reversible color change phenomenon, is generally known as a hysteresis color change phenomenon and is brought about by using the above-mentioned specific ester compound. It is an action. In the above description with respect to FIG. 1, the temperature is continuously changed for the sake of convenience, but of course, the same action and effect can be obtained only by applying two appropriate different temperature points.

In the composition of the present invention, the temperature range T _{2 to} T ₃ is changed depending on the history of temperature rise or decrease.
At the same temperature in between, two different colored states (ie, a colored state and a decolored state) are shown. For this reason,
Records can be retained by utilizing this property. Specifically, the composition of the present invention in the decolored state is treated with T
If cooling _{2 'below} the temperature becomes a colored state, which if maintained at a temperature range of T ₂ to T _3, the colored state is maintained. In addition, the composition of the present invention in a colored state is
_When it is heated to a temperature of _3'or higher, it becomes a decolored state.
_When maintained in the temperature range of _{2 to} T ₃ , the decolored state is maintained.

The composition of the present invention, in addition to the characteristic of exhibiting such a hysteresis discoloration phenomenon, can have a temperature range T _{2 to} T ₃ at which recording can be held, that is, a hysteresis width can be arbitrarily set, and There is a feature that this hysteresis width can be set wide. In this way, as a result of setting a wide hysteresis width, stable recording can be held. The characteristics of the composition of the present invention include
This is probably due to the following reasons.

That is, in the composition of the present invention, the hysteris width (temperature range T _{2 to} T ₃ ) substantially corresponds to the difference between the melting point and the cloud point of the ester compound used.
Although the reason for this is not clear, the physical behavior of the ester compound greatly changes at the melting point when the temperature rises and affects the reaction between the coexisting leuco dye and the color-developing substance, and this melting point substantially corresponds to the temperature T _3. On the other hand, when the temperature is lowered, the physical behavior of the ester compound greatly changes at the cloud point and affects the reaction between the coexisting leuco dye and the color-developing substance, and the cloud point almost corresponds to the temperature T _2. As a result, it is assumed that the hysteresis width almost corresponds to the difference between the melting point and the cloud point. And in the present invention,
Since an ester compound having 4 or more ester bonds in the molecule is used, the ester compound has a very wide selection range of the ester bond, and by changing the individual ester bond types arbitrarily, Melting point
The cloud point can be set freely and almost continuously, and the hysteresis width which is inseparable from these physical property values can be freely adjusted.

As described above, in the present invention, it is necessary to use a compound having 4 or more ester bonds, and a compound having 3 or less ester bonds has less flexibility in setting the melting point and cloud point. , It cannot be changed continuously with an arbitrary value.

The ester compound used in the present invention is
It is necessary that the molecular weight is 3000 or less. At such a molecular weight, the ester compound exhibits a clear melting point and the discoloring behavior becomes sharp, but the molecular weight is 3
If it exceeds 000, it often does not show a clear melting point, and in such a case, it is unsuitable as a composition for information recording because the discoloration behavior lacks sharpness.

As the ester compound used in the present invention,
For example, there can be mentioned compounds obtained by appropriately combining the acid component and the alcohol component listed below, and these compounds can be obtained very easily by a known esterification reaction.

* Acid component: benzoic acid, parahydroxybenzoic acid, naphthoic acid, protocatechuic acid, gallic acid, toluic acid, halobenzoic acid, aminobenzoic acid, nicotinic acid, quinolinic acid, phthalic acid, trimellitic acid, pyromellitic acid. Aromatic monocarboxylic acid or polycarboxylic acid which may have a substituent such as acid; acetic acid, chloroacetic acid, phenylacetic acid, cinnamic acid, propionic acid, butylthiopropionic acid, octylthiopropionic acid, decylthio Propionic acid, lauryl thiopropionic acid, stearyl thiopropionic acid, valeric acid, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, 12-hydroxystearic acid, oleic acid,
Aliphatic monocarboxylic acids which may have a substituent such as linoleic acid, behenic acid, cyclopentanecarboxylic acid and cyclohexanecarboxylic acid; oxalic acid, malonic acid, succinic acid, tartaric acid, maleic acid, adipic acid, azelaic acid ,
Sebacic acid, malic acid, citric acid, cyclohexanedicarboxylic acid, ethylenediaminetetraacetic acid, and other aliphatic polycarboxylic acids that may have a substituent; sulfuric acid, methyl sulfuric acid,
Sulfuric acid such as lauryl sulfuric acid or alkyl sulfuric acid; phosphoric acid such as phosphoric acid, methyl phosphoric acid or dimethyl phosphoric acid or alkyl phosphoric acid; and phosphonic acid or sulfonic acid having an alkyl group or an aryl group.

* Alcohol component: methanol, ethanol, propanol, isopropanol, butyl alcohol, isobutyl alcohol, t-butyl alcohol, pentanol, neopentyl alcohol, heptanol,
Octyl alcohol, nonyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, behenyl alcohol, benzyl alcohol, cyclohexyl alcohol, cyclohexylmethyl alcohol, glycolic acid,
Aliphatic monohydric alcohols which may have a substituent such as citric acid, malic acid and cellosolve; ethylene glycol, dielen glycol, polyethylene glycol, propylene glycol, butylene glycol, hexanediol, tartaric acid, glycerin, tri Methylolpropane, triethanolamine, pentaerythritol, glycerophosphoric acid, pentoses, hexoses, heptoses, hexitols and other aliphatic polyhydric alcohols which may have a substituent; phenol, bisphenol A, bisphenol F, Monophenols or polyphenols which may have a substituent such as 2,2′-diphenol, para-hydroxybenzoic acid, protocatechuic acid, hydroquinone, gallic acid, salicylic acid, resorcin and the like.

There are innumerable combinations of the above acid components and alcohol components, but if the molecule is designed so that it has a total of 4 or more ester bonds in the molecule and the molecular weight does not exceed 3000, then in the present invention. Are all preferably used.

In the present invention, a long-molecular compound in which an ester bond (ester group) is repeatedly included in the main chain of the molecule, such as a polyester compound formed from terephthalic acid and ethylene glycol, can be used. Compounds having a certain degree of three-dimensional spread in which a substituent having an ester bond is bonded to the molecular main chain or aromatic nucleus are preferable, and such compounds generally have a sharp melting point and exhibit a sharp discoloration behavior. it can.

Examples of such preferable ester compounds include the followings.

Ester compounds consisting of polyhydric alcohol having 4 or more OH groups in the molecule such as pentaerythritol and hexitol and various acid components; total of 4 OH groups and COOH groups in molecules such as tartaric acid and gallic acid. In the compound having the above, an ester compound obtained by combining the OH group as an alcohol component with various acid components and a COOH group as an acid component with various alcohol components; and COOH in a molecule such as ethylenediaminetetraacetic acid or pyromellitic acid Ester compounds and the like consisting of a polybasic acid having 4 or more groups and various alcohol components.

As an example of the ester compound having such a molecular design, pentaerythritol tetramyristate (melting point 58 ° C.), pentaerythritol tetrastearate (melting point 75 ° C.), pentaerythritol tetrabehenate (melting point 80 ° C.) ), Pentaerythritol tetrakis (3-n-decylthiopropionate) (melting point 38 ° C.), pentaerythritol tetrakis (3-laurylthiopropionate) (melting point 50 ° C.), mannitol hexastearate (melting point 65 ° C.), Cetyl 3,4,5-tris (acetyloxy) benzoate (melting point 87
° C), 3,4,5-tris [(1-oxohexadecyl) oxy] cetyl benzoate (melting point 79 ° C), 3,4
Lauryl 5-tris (acetyloxy) benzoate (melting point 76 ° C), Octyl 3,4,5-tris (acetyloxy) benzoate (melting point 54 ° C), 3,4,5-Tris [(1-oxohexadecyl) ) Oxy] propyl benzoate (melting point 62 ° C), tetramethyl 1,2,4,5-benzenetetracarboxylate (melting point 142 ° C), tetraethyl 1,2,4,5-benzenetetracarboxylate (melting point 54 ° C) , Tetraethylethylenediaminetetraacetate (melting point: 32 ° C.) and the like can be mentioned, but of course the invention is not limited thereto.

The amount of the above-mentioned ester compound to be used may be appropriately selected according to the desired hysteresis width and color density at the time of color development, and is not particularly limited.
Usually, it is preferable to use the leuco dye in an amount of about 0.1 to 1000 parts by weight based on 1 part by weight.

The composition of the present invention is usually characterized in that the temperature range (hysteresis width) required for holding a record can be freely set by using one kind of ester compound. Two or more kinds of ester compounds can be used in combination for the purpose of adjusting the color density of the above or finely adjusting the color change behavior.
Other additives listed below can also be used.

Examples of such additives include alcohols such as methyl alcohol, ethyl alcohol, butyl alcohol, octyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol and behenyl alcohol; dioctyl phthalate. Decyl caprate, decyl laurate, myristyl laurate, lauryl myristate, stearyl palmitate, cetyl p-t-butylbenzoate, dilauryl thiodipropionate, dimyristyl thiodipropionate, stearylbenzoate, benzyl stearate, benzoic acid Esters having less than 4 ester bonds in the molecule such as benzyl; benzylidene p-
Azomethines such as toluidine and benzylidene / butylamine; ketones such as acetone, acetophenone, benzophenone and distearyl ketone; ethers such as diethyl ether, distearyl ether, diphenyl ether, cellosolve; lauric acid, myristic acid, palmitic acid, stearic acid , Behenic acid, benzoic acid, naphthoic acid, propionic acid, butylthiopropionic acid, laurylthiopropionic acid, stearylthiopropionic acid, and other organic carboxylic acids. The amount of such additives used is usually the ester compound 1 used in the present invention.
It may be about 1 to 100 parts by weight with respect to 00 parts by weight.

Among these additives, particularly, the organic carboxylic acids used as the acid component of the ester compound to be blended in the composition of the present invention, or an ester having less than 4 esters in the molecule having the organic carboxylic acids as a constituent element Esters containing a bond are preferably used because the temperature range can be finely adjusted while maintaining a wide hysteresis width.
A wide hysteresis width is maintained even when using an organic carboxylic acid having a melting point difference of less than ± 5 ° C or an ester having less than 4 ester bonds in the molecule as an additive, as an additive. The temperature range can be finely adjusted as it is.

The composition of the present invention is a mixture of the components,
It can be used as a form in which an ester compound is melted and mixed with other components, and the composition is used by being uniformly dispersed in ink, paint, synthetic resin, etc., similarly to a usual pigment component. Although it is also possible, it is more preferable to use the compound of the present invention encapsulated in an independent micro-closed system.

In order to achieve this object, various conventionally known microencapsulation techniques can be applied.

As such a microencapsulation technique,
Coacervation method, interfacial polymerization method, in situ
(In situ) polymerization method, liquid hardening coating method, air suspension coating method, spray drying method and the like can be mentioned, and one or a combination of two or more of them can be used to provide a particle size of 1 including the composition of the present invention. Single-layer or multi-layer microcapsules having a thickness of about 50 μm can be obtained.

Preferred examples of the film-forming substance used at that time are polyvalent amine and carbonyl compound for forming a polyurea film, and polybasic acid chloride and polyvalent amine for forming a polyamide film. , Polyvalent isocyanate and polyhydroxy compound for forming polyurethane film, polybasic acid chloride and polyhydroxy compound for forming polyester film, epoxy compound and polyvalent amine for forming epoxy resin film, melamine resin film Melamine formalin prepolymer for forming
Examples thereof include urea / formalin prepolymer for forming a urea resin film, gelatin, ethyl cellulose, polyvinyl alcohol, carboxymethyl cellulose, polystyrene, polyvinyl acetate and the like.

The microcapsule film is preferably a thermosetting film which is excellent in heat resistance and solvent resistance.

The microcapsule granules containing the composition of the present invention thus obtained are used by being uniformly dispersed in various inks, paints, synthetic resins, etc., as in the case of using the composition as it is. be able to.

At this time, in each of the above-mentioned media, if desired, known general dyes, fluorescent dyes, fluorescent brighteners, ultraviolet-emitting dyes, general pigments, fluorescent pigments, phosphorescent pigments, luminescent pigments,
Other colorants such as metallic luster pigments, extender pigments, thermochromic colorants, photochromic colorants; ultraviolet absorbers, antioxidants, water repellents, flame retardants, dulling agents, matting agents, cross-linking agents, fragrances, Antibacterial agent, deodorant, insect repellent, repellent,
Preservatives and the like can be added.

Further, these can be made to coexist in the above-mentioned microcapsules as long as they do not impair the various properties of the composition of the present invention.

When the above-mentioned other coloring agents are used, it goes without saying that a reversible discoloration phenomenon between two different kinds of colors can be provided, and these other coloring agents and the composition of the present invention can be used. By using two or more kinds in combination, it is possible to record and hold multi-stage discoloration.

[0041]

The reversible color change thermosensitive recording composition of the present invention comprises
Records can be retained and erased repeatedly, and by applying them as various information recording materials, resource saving,
Energy saving can be achieved. Furthermore, since the temperature range required for record retention can be set freely, it can be applied to an extremely wide range of applications.

Therefore, it is of course possible to replace the conventional coating agent for heat-sensitive recording paper and use it, and it is also possible to record information on everything if it is used as various ink ribbons or thermal transfer media.

When applied to a writing board, a white board, a black board (blackboard), etc., by using a hot pen and a cold eraser, or a combination of a cold pen and a heat eraser, the recording of a negative image or a positive image is retained. And can be erased.

Further, the composition of the present invention can be used as various labels, indicators, anti-counterfeiting materials, etc., for example, detection of supercooled state or overheated state of foods, various circuits of electric switchboards. It is used as various danger prevention materials and warning display materials for the purpose of detecting electric leakage, overcurrent status, etc., as well as various ID cards, prepaid cards, cash cards, magnetic cards, stamps,
When applied to bills, securities, alteration prevention seals, etc., it can be used as a forgery prevention material or a forgery detection material.

Also, paying attention to abundant color variations and peculiar discoloring behaviors, etc., it is applied to various clothing, ornaments, bedding, interior goods, toys, learning materials, writing instruments, stationery, and other daily goods. By doing so, it is possible to obtain a unique product having a high added value, which is provided with preference, decorativeness, and unexpectedness.

[0046]

EXAMPLES Examples of the present invention will be given below, but the present invention is not limited thereto.

In the following Examples 1 to 35, the temperature and coloration state of each color change cycle were measured by loading an appropriate amount of the composition into a test tube having an inner diameter of 8 mm and inserting a thermometer at the same time to change the temperature. While doing, the color condition was visually determined.

Example 1 6- which is a leuco dye (hereinafter simply referred to as "component (a)")
(Dimethylamino) -3,3-bis [4- (dimethylamino) phenyl] -1 (3H) -isobenzofuranone (crystal violet lactone, hereinafter simply referred to as C.V.
L. 1 part by weight and 4,4 '-(1-methylethylidene) bis-phenol (hereinafter simply referred to as bisphenol A) which is a color-developing substance (hereinafter simply referred to as (b) component).
3 parts by weight) is melted by heating to 26 parts by weight of pentaerythritol tetrakis (3-n-decyl-thiopropionate), which is an ester compound (hereinafter simply referred to as (ha) component), to obtain a homogeneous composition. 30 parts by weight of the product were obtained.
The composition exhibited a deep blue color in the color-developed state, and the respective temperatures in the color change cycle shown in FIG. 1 were as follows.

[0049] In the same manner as _{T 2'= 3 ℃ T 2 =} 7 ℃ T 3 = 25 ℃ T 3'= 30 ℃ Example 2 to 27 Example 1, the composition of the formulation described in Table 1 to Table 3 I got a thing. Fig. 1 shows the color of the obtained composition when it was developed.
Tables 1 to 3 below show the respective temperatures of the color change cycle in.

[0050]

[Table 1]

[0051]

[Table 2]

[0052]

[Table 3]

Example 28 A composition was obtained in the same manner as in Example 5 except that 1 part by weight of 3-laurylthiopropionic acid was added as an additive.
At the time of color development, the composition showed a deep blue color like the composition of Example 5, and the respective temperatures in the color change cycle were as follows.

[0054] to obtain a reversible color change composition with _{T 2'= 15 ℃ T 2 =} 20 ℃ T 3 = 35 ℃ T 3'= 40 ℃ Example 29-35 formulations shown in Table 4 below. Table 4 shows the color of the composition during color development and each temperature in the color change cycle.

[0055]

[Table 4]

Example 36 30 parts by weight of the composition obtained in Example 5 and an epoxy resin ("Epicoat 828" manufactured by Yuka Shell Epoxy Co., Ltd.)
6 parts by weight of a uniform hot solution was added to 100 parts by weight of a 5% aqueous solution of hydroxyethyl cellulose at 90 ° C., and the mixture was stirred to disperse into oil droplets having a diameter of about 5 μm. Then, a curing agent for epoxy resin (“Epicure U 2 parts by weight of “Yuka Kachel Epoxy Co., Ltd.” was added, and the reaction was continued for 2 hours.

Then, the mixture was cooled, and the produced microcapsule particles were separated by filtration, washed with water and dried to obtain about 38 parts by weight of the composition-encapsulated microcapsule granules.

Next, 20 parts by weight of the thus-obtained granular material was heated to 40 ° C. to prepare 100% 10% aqueous gelatin solution.
1 part by weight with stirring to uniformly disperse
The pH of the system was adjusted to 5 with 0% acetic acid. Then, 100 parts by weight of a 5% aqueous solution of gum arabic was added to this dispersion with stirring and cooled to 3 ° C. After that, 5 parts by weight of 10% formalin aqueous solution was added, and stirring was continued for another 10 minutes.
The pH of the system is adjusted to 10 while gradually adding% caustic soda solution.
Then, the temperature was raised to 50 ° C. over 1 hour.

The resulting capsule dispersion having a particle size of 7 to 8 μm was separated by filtration, washed with water, air-dried, and further dried at 80 ° C. for 2 hours to give about 30 parts by weight of the reversible color-changing composition-containing multi-layer. Microcapsule granules were obtained.

Example 37 About 30 parts by weight of microcapsule granules were obtained in the same manner as in Example 36 except that the composition of Example 24 was used in place of the composition of Example 5.

Example 38 About 30 parts by weight of microcapsule granules were obtained in the same manner as in Example 36 except that the composition of Example 25 was used in place of the composition of Example 5.

Example 39 About 30 parts by weight of microcapsule granules were obtained in the same manner as in Example 36 except that the composition of Example 26 was used in place of the composition of Example 5.

Example 40 About 30 parts by weight of microcapsule granules were obtained in the same manner as in Example 36 except that the composition of Example 27 was used in place of the composition of Example 5.

Example 41 To 200 parts by weight of the composition obtained in Example 20, 50 parts by weight of a polyisocyanate (“Millionate MR” manufactured by Nippon Polyurethane Industry Co., Ltd.) was added, and the mixture was heated and stirred to be uniform. A different dispersion was obtained. Next, the above-mentioned uniform dispersion liquid was added to 2000 parts by weight of an aqueous solution containing 10 parts by weight of colloidal tricalcium phosphate as a dispersion stabilizer and 0.2 parts by weight of sodium dodecylbenzenesulfonate and heated at 60 ° C. Using a stirrer, the average particle size of the uniform dispersion is 3 μm.
The stirring speed was adjusted so that To this dispersion, 10 parts by weight of xylylenediamine was added dropwise, and the temperature was 60 ° C.
After the dispersion is continuously stirred for about 3 hours to complete the reaction, the dispersion stabilizer is decomposed and removed with hydrochloric acid, filtered, washed with water and dried to give about 260 parts by weight of the composition-encapsulated microcapsule granules. Obtained.

Next, the granular material 100 thus obtained is obtained.
100 parts by weight of an anionic surfactant (“Demol N” manufactured by Kao Corporation) was added to 1000 parts by weight of the aqueous solution with stirring to disperse the solution uniformly, and then melamine. Drop 20 parts by weight of formalin prepolymer,
Heated to 80 ° C. with continuous stirring.

Then, dilute hydrochloric acid was added dropwise to adjust the pH of the system to 4.5.
After stirring for 2 hours at this temperature, allow to cool,
After filtration, washing with water and drying, about 120 parts by weight of the composition-encapsulated microcapsule granules were obtained.

Example 42 10 parts by weight of the microcapsule granules obtained in Example 36 were uniformly dispersed in 50 parts by weight of a 10% aqueous solution of polyvinyl alcohol, and then coated on a recording high-quality paper having a thickness of about 80 μm. It was applied with a coating roll so that the amount was 20 g / m ² . Then, it was slowly dried at a temperature of 60 ° C. to obtain a reversible color-changing thermosensitive recording paper showing white at room temperature (25 ° C.).

A cold pen (pen point temperature 4
℃), record the letter "A", room temperature (25 ℃)
When left for one month at, the characters were still recorded even after one month, and semipermanent record retention was possible.

On the other hand, when warm air (50 ° C.) was applied to the character portion, the character disappeared instantly and the original white recording paper was restored. After that, such record retention and erasure could be repeated many times.

On the other hand, when the recording paper was stored in a refrigerator having an internal temperature of 8 ° C. and taken out to a room temperature (25 ° C.), the recording paper exhibited a deep blue color on the whole surface. . When the recording paper was set in an ordinary printer and printed with a thermal head, white characters were printed on the blue recording paper at room temperature. This character remained printed even when left at room temperature for one month, and semi-permanent recording was possible. Then, the printed recording paper was left in the refrigerator again, and when it was taken out, it returned to the original blue recording paper.

Thereafter, such recording retention and erasure could be repeated many times.

Therefore, the recording paper obtained in this embodiment exhibits the functions of both the positive image type recording paper and the negative image type recording paper by simply controlling the history of temperature increase or decrease. It was a very good thing possible.

Example 43 10 parts by weight of the microcapsule granules obtained in Example 36,
Polyfunctional acrylic monomer (trade name, KAYARAD D
PHA; manufactured by Nippon Kayaku Co., Ltd., 18 parts by weight;
KAYARAD TMPTA; manufactured by Nippon Kayaku Co., Ltd. 4 parts by weight, base resin (trade name, Epikote 828)
Acrylate; 8 parts by weight of Yuka Shell Epoxy Co., Ltd. and a benzophenone-based photopolymerization initiator (trade name, KAYA)
CURE MBP; manufactured by Nippon Kayaku Co., Ltd., 0.3 parts by weight of UV curable printing ink A was prepared. Then, in place of 10 parts by weight of the microcapsule granules obtained in Example 36 in the above formulation, Examples 37 to 4 were used.
Printing inks B, C, and C
D and E were prepared.

Using the above-mentioned total of 5 colors of printing ink,
A geometric pattern is screen-printed on a polyurethane laminate sheet, and then a parallel high-pressure mercury lamp (80 W / c
m) was used for irradiation for 10 seconds at an irradiation distance of 10 cm to obtain a writing board made of a polyurethane sheet.

This writing board is black, red, yellow,
A total of 5 colors, green and blue, are colored in a geometric pattern.
It had a function as a display, but 5
After heating the entire surface with warm air of 0 ° C., the heating was stopped, resulting in a writing board with a white surface.

When various characters and figures were written on this writing board with a cold pen (pen tip temperature of 8 ° C.), the handwriting portion was colored in black, red, yellow, green, and blue in a total of five colors. Each department developed a different color and was very unique.

The multicolored characters and figures drawn in this way are maintained at room temperature (25 ° C), but are warmed once with warm air (50 ° C) or touched with a fingertip several times. Then, it disappeared due to the frictional heat, and the writing board returned to the original white writing board. Such reversible recording retention and erasure could be repeated many times.

Example 44 20 parts by weight of the microcapsule granules obtained in Example 36,
Matsumine Binder D-35 (trade name, manufactured by Matsui Dye Chemical Industry Co., Ltd., acrylic ester aqueous resin emulsion) 70 parts by weight, Fixer F (trade name, manufactured by Matsui Dye Chemical Industry Co., Ltd., acrylic acid) 5 parts by weight of an epoxy resin crosslinking agent for ester resin) was mixed to prepare a resin printing paste for cloth.

Using the printing paste, a square solid pattern having a side of 30 cm was printed on a cotton T-shirt with a screen plate (80 mesh) and heat-treated at 100 ° C. for 2 minutes.

The T-shirt thus obtained had a white color on the whole surface, but when left for a while in a refrigerator adjusted to a room temperature of 2 ° C., only the imprinted part had a vivid blue color. It was When my favorite pattern or character was drawn on this printing part using a heating medium such as an iron or an electric iron, a white message that could not disappear at body temperature or room temperature (25 ° C) could be written. This message disappeared immediately when left in the refrigerator again, and the original blue image could be obtained. In addition, a white T-shirt could be obtained by heating with a dryer.

Writing and erasing such a message are
I was able to repeat it many times, and I got a very unique T-shirt where I could write my favorite message. Example 45 Parchment paper (98 g /
SK Dyne 101 (adhesive, manufactured by Sekisui Chemical Co., Ltd.) on a silicon processed surface of m ² ) with a roll coater to a thickness of 4
The entire surface was applied to 0 μm, air-dried, and then a polyester film (thickness: 20 μm) was attached thereon to form a base sheet for tack seal.

Next, 20 parts by weight of the microcapsule granules obtained in Example 41 and 3 parts by weight of glow pink MFB (pink fluorescent pigment, manufactured by Matsui Dye Chemical Industry Co., Ltd.) were used as EV-40.
(Ethylene-vinyl acetate copolymer, manufactured by Mitsui Toatsu Chemicals, Inc.) A printing ink uniformly dispersed in 100 parts by weight of a 25% xylene solution was used to form a polka dot pattern on the polyester film of the base sheet. (Diameter 1 cm) was printed on a screen plate (100 mesh) and dried sufficiently.

Then, a transparent polypropylene film (thickness: 50 μm) is laminated on the surface of the substrate sheet (the surface having a polka dot pattern) thus obtained under heating to obtain a tack seal having a polka dot pattern. It was

The polka dot pattern was purple at room temperature of 25 ° C., but turned pink when exposed to a temperature of 60 ° C. or higher, and remained pink even when it was returned to room temperature. However, when the surface was cooled with a refrigerant of -20 ° C, the color returned to the original purple immediately. Such a discoloration phenomenon could be repeated many times.

When such a tack seal was half-cut for each polka dot pattern and attached to each breaker of the switchboard, only the tack seal attached to the breaker that generated heat due to overcurrent changed to pink, and other Since all were purple (observed at room temperature), abnormal wiring could be detected immediately.

Since such a tack seal discolored in pink can be restored to purple by a refrigerant at -20 ° C, it can be repeatedly used for detecting abnormality.

[Brief description of drawings]

FIG. 1 is a graph showing the hysteresis characteristic of the change in color density of the composition of the present invention with temperature.

Claims (2)

[Claims] 1. (a) a colorless or light-colored leuco dye, (b)
A reversible color-changing thermosensitive recording composition comprising a color-developing substance capable of coloring the leuco dye and (c) an ester compound having at least 4 ester bonds in the molecule and having a molecular weight of 3000 or less. .. 2. The reversible color-changing thermosensitive recording composition according to claim 1, which is encapsulated in microcapsules.