JPH111644A - Heat history indication ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink composition which can indicate the elapsed time of heat history under constant temperature conditions and can form a clear image. SOLUTION: This composition comprises an electron-donating compound, an electron-accepting compound, a solvent and a silicone oil. The silicone oil used is exemplified by an amino-modified silicone oil, a carboxyl-modified silicone oil or a polyether-modified silicone oil. The silicone oil is used in an amount of 0.01-10 wt.% based on the entire weight of the composition. The composition may further contain an oil-soluble resin. It can be used as an ink for e.g. ink jet recording system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ink composition capable of displaying a thermal history. More specifically, the present invention relates to an ink composition which can display aging time under a constant temperature condition with high reproducibility, has excellent image clarity, and is useful for a recording method such as ink jet.

[0002]

2. Description of the Related Art Canned juices (for example, canned coffee, canned oolong tea, canned soup, etc.) are sold in the winter by being warmed by a hot bender in a vending machine. As described above, if canned juice is stored for a long period of time (for example, about 2 to 4 weeks) while keeping the temperature of the juice, the quality of the juice is deteriorated and often becomes a target of a claim. Since glucose is generated when the can juice is kept warm, the heat history of the can juice is determined based on the increase in glucose inside the can. However, such an analysis is performed by a public organization, which is time-consuming and expensive, and has a problem that the response to the claims is delayed. Further, for the enforcement of the PL law, the necessity of a method that can be generally understood is emphasized as a method of displaying the elapsed time with respect to the heat history of can juice.

Conventionally, a recording method using an electron-donating color-forming organic compound has been widely used as a method for indicating the elapsed time. Examples of the ink composition in such a recording method include, for example, JP-A-60-124681 and JP-A-62
No. 179640, JP-A-7-109423 and the like.

[0004]

However, when such a conventional ink composition is used, the print formed on the can tends to be crater-like, and it is difficult to make the coating film thickness uniform. In addition, there has been a problem that the display time (discoloration / decoloring speed) of the elapsed time varies.

Another problem is that it is difficult to display the time elapsed under a constant temperature condition without detecting the heat history at the distribution stage or the like. Thus, up to now, in can products (canned juice, canned food, etc.), it is possible to display, with high reproducibility, the aging time of heat retention under a constant temperature condition such as a hot bender, and to form an image with excellent clarity. The ink composition is not specifically disclosed, and the manufacturer of canned juice (such as soft drink) must use a method based on the amount of glucose in the can to determine the heating history of the canned juice. This is not the case.

An object of the present invention is to provide an ink composition which can display the aging time of heat history under a constant temperature condition with high reproducibility and can form a clear image. Another object of the present invention is to provide an ink composition capable of forming a print having high adhesiveness as well as the above-described excellent characteristics.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, when the ink composition is composed of an electron donating compound, an electron accepting compound, a solvent and silicone oil, a constant temperature condition is required. The present inventors have found that an ink composition capable of displaying the elapsed time of the heat history below with high reproducibility and capable of forming a clear image can be obtained, thereby completing the present invention. The invention of claim 1 is an ink composition containing an electron donating compound, an electron accepting compound, a solvent and silicone oil.

[0008] Since the ink composition of the present invention contains silicone oil, the familiarity of the ink to the printing object is reduced, and a so-called kind of repelling state can be formed. As a result, the ink shrinks on the printing object, and uniform and uniform printing is possible, and the speed of discoloration and decoloring of the formed image can be made constant, and the print formability can be improved. The present invention is an ink composition utilizing such properties of silicone oil.

As the silicone oil, at least one selected from amino-modified silicone oil, carboxy-modified silicone oil, polyether-modified silicone oil, alkyl-modified silicone oil, alkoxy-modified silicone oil, and fluorine-modified silicone oil can be used. . The content of the silicone oil is 0.01 to 10% by weight based on the total amount of the ink composition. The invention according to claim 2 is characterized in that the silicone oil is an amino-modified silicone oil, a carboxy-modified silicone oil, a polyether-modified silicone oil, an alkyl-modified silicone oil, an alkoxy-modified silicone oil,
The ink composition according to claim 1, wherein the ink composition is at least one selected from a fluorine-modified silicone oil. Also,
The invention according to claim 3 is characterized in that the content of silicone oil is 0.0
The ink composition according to claim 1, wherein the content is 1 to 10% by weight.

[0010] The electron donating compound functions as a colorant. As the electron donating compound (hereinafter, sometimes referred to as a coloring agent), triphenylmethanephthalides, fluorans, rhodamine lactams, leuco auramines, spiropyrans, and the like can be used. The electron accepting compound functions as a developer for the electron donating compound. As the electron-accepting compound (hereinafter sometimes referred to as a developer), monophenols, diphenols, triphenols, and the like can be used.

[0011] The solvent also has a function as a desensitizer for suppressing coloration of the colorant. As the solvent, for example, aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons,
Alcohols, ketones, esters, ethers, alcohol esters, ketone alcohols, ether alcohols, ketone ethers, ketone esters, ester ethers, and the like can be used.

When an oil-soluble resin (hereinafter sometimes simply referred to as a resin) is added to the above-mentioned components, the adhesiveness to a printing substrate can be improved and the viscosity of the ink composition can be adjusted. As the resin, for example, an aliphatic hydrocarbon resin, an aromatic hydrocarbon resin, an acrylic resin, a phenol resin, an amino resin, a ketone resin, or the like can be used. The invention of claim 4 further comprises:
The ink composition according to any one of claims 1 to 3, further comprising an oil-soluble resin.

The ink composition of the present invention can be suitably used as an ink composition for inkjet. A fifth aspect is an ink composition using the ink composition according to any one of the first to fourth aspects for inkjet.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

(Ink Composition) The ink composition of the present invention contains an electron donating compound, an electron accepting compound, a solvent, and silicone oil.

In the ink composition of the present invention, the electron donating compound is used in combination with an electron accepting compound, and the electron donating compound functions as a coloring agent, and the electron accepting compound functions as a developer. Further, the solvent suppresses coloring of the colorant (electron donating compound). That is, the colorant can form a color by reaction with a color developer (electron accepting compound). However, since the ink composition of the present invention contains a solvent, the coloration of the colorant in the ink composition Is suppressed, and the colorant can be colored by evaporation or evaporation of the solvent after printing. Therefore, immediately after printing, the ink composition of the present invention (for example, in about several seconds)
When the color develops and is maintained at a constant temperature, discoloration / decoloration starts to start. That is, it has a start function, and when left under a condition of a constant temperature, its thermal history starts to be detected. The reaction between the colorant and the developer is irreversible. In addition, the detection period can be adjusted according to the type and amount of the color developer.

Further, since the ink composition of the present invention contains silicone oil, the discoloration / decolorization has little variation with the passage of time and the heat history can be displayed with high reproducibility. Further, the coating film of the ink composition of the present invention has a uniform or almost uniform film thickness and the same diameter or substantially the same as shown in FIG. 1 because the ink shrinks on the substrate as described above. It is possible to improve the print formability. Therefore, a clear image (print) having a high color density can be formed. FIG. 1 is a diagram showing the state of a coating film when the ink composition of the present invention is formed using an ink composition containing silicone oil, and FIG. 2 is a diagram showing a case where an ink composition containing no silicone oil is used. FIG. 4 is a view showing a state of a coating film of FIG. In FIGS. 1 and 2, 1 indicates a coating film for printing, and 2 indicates a coated surface of metal.

In FIG. 1, since the ink composition containing silicone oil is used, the familiarity between the ink and the coated surface (printed surface) is low, and the contact area between the ink and the coated surface is reduced. Then, it shrinks on the printing surface. Therefore, the thickness of the coating film 1 for printing is uniform or almost uniform, and a circle having the same diameter or almost the same diameter is formed. In addition, the diameter of the coating film 1 is about 0.7 mm. Therefore, a clear image having a high color density is formed without unevenness in the color density.

On the other hand, in FIG. 2, since the ink composition containing no silicone oil is used, the coating film 1 for printing has an uneven film thickness, and the outer edge or the peripheral portion is oozing. Therefore, the color density of the coating film 1 for printing is thin at the central portion 1a, the metal surface of the printing surface is visible at the central portion 1a, and the outer edge portion 1b is dark, and the color density is uneven in the entire coating film. Has occurred. Therefore, the color of the coating film becomes dark and light, and a clear image cannot be formed.

Further, when a resin is contained in the above component,
The adhesiveness can be improved and the viscosity of the ink composition can be adjusted.

(Electron-donating compound) The electron-donating compound (coloring agent) is not particularly limited as long as it is an electron-donating organic compound having coloration properties. Such colorants include triphenylmethanephthalides, fluorans,
Rhodamine lactams (e.g., lactams of 2- {3,6-bis (diethylamino) -9- (o-chloroanilino) xanthylbenzoate), leukoalumines (e.g., benzoylleucomethylene blue, etc.), spiropyrans (e.g., 6'-chloro-8'-methoxy-benzoindolino-spiropyran, 6'-bromo-3
'-Methoxy-benzoindolino-spiropyran, etc.)
Can be used. The coloring agents can be used alone or in combination of two or more.

As the coloring agent, triphenylmethanephthalides and fluorans can be suitably used. Specifically, as triphenylmethanephthalides, for example, 3,3-bis (p-dimethylaminophenyl) phthalide, 3,3-bis (p-dimethylaminophenyl)
-6-dimethylaminophthalide, 3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3-
(2'-hydroxy-4'-dimethylaminophenyl)
-3- (2'-methoxy-5'-chlorophenyl) phthalide, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl) phthalide, 3- (2'-hydroxy-4'-diethylaminophenyl) -3- (2'-methoxy-5'-
Methylphenyl) phthalide, 3- (2′-methoxy-4)
'-Dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-methylphenyl) phthalide and the like.

The fluorans include, for example, 3-cyclohexylamino-6-chlorofluoran, 3-dimethylamino-5,7-dimethylfluoran, 3-diethylamino-7-chlorofluorane, 3-diethylamino-7-
Methylfluoran, 3-diethylamino-6-methyl-
7-chlorofluorane, 2- (N-phenyl-N-methylamino) -6- (NP-tolyl-N-ethylamino) fluoran, 3- (Np-tolyl-N-ethylamino)- 6-methyl-7-anilinofluoran, 3-pyrrolidino-6-methyl-7-anilinofluoran, 3-
Diethylamino-7,8-benzfluoran, 2- {N
-(3-trifluoromethylphenyl) amino} -diethylaminofluoran, 3-diethylamino-7- (o
-Chloroanilino) fluoran, 3-dibutylamino-
7- (o-chloroanilino) fluoran, 3- (N-methyl-N-amylamino) -6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7 -Anilinofluoran, 3-diethylamino-6-methyl-7-anilinofluoran,
3- (N, N-diethylamino) -5-methyl-7-
(N, N-dibenzylamino) fluoran, 3-diethylamino-5-chloro-7- (N-trifluoromethylanilino) fluoran, 3-diethyl-5-chloro-7
-(Α-phenylethylamino) fluoran, 3- (N
-Ethyl-p-toluidino) 7- (α-phenylethylamino) fluoran, 3-diethylamino-7- (o-
Methoxycarbonylphenylamino) fluoran, 3-
Diethylamino-5-methyl-7- (α-phenylethylamino) fluoran, 3-diethylamino-7-piperidinofluoran, 2-chloro-3- (N-methyltoluidino) -7- (pn-butylanilino) Fluoran, 3- (N-methyl-N-isopropylamino) -6
-Methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3- {N-
Ethyl-N- (2-ethoxypropyl) amino} -6
Methyl-7-anilinofluoran, 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo-7-
α-naphthylamino-4′-bromofluoran, 3-diethylamino-6-chloro-7-anilinofluoran,
3-diethylamino-6-methyl-mesitidino-4 ′,
5'-benzofluoran, 3-N-methyl-N-isobutyl-6-methyl-7-anilinofluoran, 3-N-
Methyl-N-isoamyl-6-methyl-7-anilinofluoran, 3-diethylamino-6-methyl-7- (2
', 5'-dimethylanilino) fluoran and the like.

In the present invention, the amount of the colorant used is 0.1 to 10% by weight based on the total amount of the ink composition. If the amount of the colorant used is too large, the colorant precipitates, and the ground color tends to remain, making it difficult to visually recognize the end point due to discoloration and decoloration. On the other hand, when the amount is too small, the color developability is low, and the change in density and change in hue are difficult to visually recognize, which is not preferable. The amount of colorant used is
Within the above range, 0.5 to 5% by weight is preferable.

(Electron-Accepting Compound) As the electron-accepting compound (developing agent), for example, one phenolic hydroxyl group is used.
Alternatively, a compound having two or more compounds can be used, and examples thereof include monophenols, diphenols, and triphenols. The developers can be used alone or in combination of two or more.

Examples of the monophenols include monohydroxyphenyl compounds (for example, 4-hydroxybenzophenone, p-hydroxydiphenyl, 4-hydroxydiphenylamine, p-cumylphenol, p-phenolsulfonamide, 4-hydroxybenzene Methyl sulfonate, 4-hydroxyphenylmethyl ketone, etc., phenylcarboxylic acid compounds (for example, oxybenzoic acid esters such as benzyl p-hydroxybenzoate, dimethyl 2-hydroxyphthalate, diphenyl 2-hydroxyphthalate) An oxyphthalic acid ester of 4'-hydroxysalicylic acid anilide,
5-benzylsalicylic acid anilide, etc.), monohydroxynaphthalene-based compounds (for example, α-naphthol, β-
Oxynaphthalenes such as naphthol, 2-methyl-1-naphthol and 8-amino-2-naphthol; oxynaphthoic acids such as 1-oxy-2-naphthoic acid and 2-oxy-3-naphthoic acid; 2-acetonaphthone; Naphthalenesulfonic acid).

Examples of the diphenols include bisphenol compounds and dihydroxynaphthalene compounds (for example, dioxynaphthalene such as 1,3-dioxynaphthalene and 1,4-dioxynaphthalene, and 1,4-dihydroxynaphthalene mono compound). Dioxynaphthalene alkyl ethers such as propyl ether, and dioxynaphthalene aryl ethers such as 1,4-dihydroxynaphthalene monobenzyl ether).

The bisphenol compounds include, for example, compounds represented by formulas (1a) to (1f).

[0028]

Embedded image (Wherein, R ¹ and R ² are the same or different and each represents an alkyl group; R ³ is an alkylene group, a cycloalkylene group, or an arylene group; R ⁴ is an alkylene group; n is an integer of 1 to 10) Is)

In the formulas (1a) to (1f), the alkyl group includes, for example, a linear or branched alkyl group having about 1 to 10 carbon atoms such as methyl, ethyl, propyl, isopropyl and butyl. Preferably an alkyl group having 1 to 6 carbon atoms). As the alkylene group, for example,
C1-C1 such as methylene, ethylene and propylene groups
About 0 alkylene groups can be exemplified. The cycloalkylene group includes, for example, a cyclohexylene group, and the arylene group includes, for example, a phenylene group. N is an integer of 1 to 10.

More specifically, as the bisphenol compound, for example, methylene bisphenol, 4,4 '
-Ethylidene bisphenol, 4,4 '-(2-ethylhexylidene) bisphenol, and the like.

Examples of triphenols include, for example, 3,
4,5-trihydroxybenzoic acid-C _1-18 alkyl ester compounds and the like can be used.

In the present invention, as the color developer, diphenols, especially bisphenol compounds are preferably used. The amount of the developer used is 0.2 to 40% by weight based on the total amount of the ink composition. When the amount of the developer used is too large, the developer precipitates and the ground color remains, and it is difficult to confirm the end point. On the other hand, if the amount is too small, the coloring density is low, and it is difficult to visually recognize a change in density and a change in hue. The developer is preferably used in an amount of 1 to 25% by weight in the range of the amount used.

In the present invention, the detection period can be adjusted depending on the type and content of the color developer.

(Solvent) As the solvent, any solvent can be used without particular limitation as long as it can dissolve the coloring agent and the color developing agent and has volatility. When the following resin is used, it is preferable to use a solvent that can further dissolve the resin. Further, the solvent can also function as a desensitizer for suppressing coloration. Examples of the solvent include aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, alcohols, ketones, esters, ethers, alcohol esters, ketone alcohols, ether alcohols, and ketone ethers. , Ketone esters, ester ethers and the like can be used. The solvents can be used alone or in combination of two or more.

Examples of the aliphatic hydrocarbons include, for example, gasoline, petroleum, benzene, mineral spirit, petroleum naphtha, M. & P. Examples include naphtha, and aromatic hydrocarbons include, for example, benzene, toluene, xylene,
p-cymene, decalin, tetralin and the like. Examples of the halogenated hydrocarbons include, for example, trichloroethylene, perchloroethylene, chloroform, carbon tetrachloride, chlorobenzene, bromobenzene, dichlorobenzene, and the like.

Alcohols include, for example, methanol,
Ethanol, isopropanol, amyl alcohol, 2
-Ethyl butyl alcohol, methyl amyl alcohol,
Examples include aliphatic alcohols such as 2-ethylhexyl alcohol, alicyclic alcohols such as cyclohexanol, and aromatic alcohols such as benzyl alcohol.

Ketones include, for example, acetone, methyl ethyl ketone, diethyl ketone, methyl butyl ketone,
Methyl isobutyl ketone, dipropyl ketone, methyl amyl ketone, methyl n-hexyl ketone, methyl dipropyl ketone, aliphatic ketones such as diisobutyl ketone, alicyclic ketones such as methyl cyclohexane non-,
Examples include mesidyl ketone, acetonitrile acetone, and the like. Examples of the esters include acetates, propionates, butyrates, and formates. Ethers include, for example, diethyl ether, diisopropyl ether, dibutyl ether, diethyl carbitol, diethyl cellosolve, and the like.

Further, alcohol esters (eg, ethyl lactate, isopropyl lactate, butyl lactate, ethyl oxypropionate, diethyl oxymaleate, etc.), ketone alcohols (eg, acetonymethanol, diacetone alcohol, dihydroxylacetone, etc.) Pyruvyl alcohol, etc.), ether alcohols (for example,
Glycidol, glycol ether, cellosolve, methyl cellosolve, isopropyl cellosolve, butyl cellosolve, benzyl cellosolve, carbitol, methyl carbitol, butyl carbitol, triethylene glycol monoethyl ether, etc., ketone ethers (eg, acetal ethyl ether, acetonyl) Methanol ethyl ether, methyl ethoxyethyl ether, etc.), ketone esters (for example, ethyl acetoacetate,
Ethyl pyruvate and the like, and ester ethers (for example, cellosolve acetate, methyl cellosolve acetate, butyl cellosolve acetate, carbitol acetate, methyl carbitol acetate, butyl carbitol acetate, 3-methoxybutyl acetate, etc.) can be used.

As the solvent, ketones, aromatic hydrocarbons and alcohols can be suitably used. In addition, aromatic hydrocarbons are often used as a mixed solvent with alcohols. The amount of the solvent used is 2 to the total amount of the ink composition.
0 to 99.2% by weight. If the amount of the solvent is too large, the viscosity is undesirably reduced. On the other hand, if the amount is too small, precipitation of solid content and an increase in viscosity are undesirably caused. A suitable amount of the solvent is 30 to 95% by weight.

(Silicone Oil) A feature of the ink composition of the present invention resides in that the above components (colorant, developer, solvent) and silicone oil are combined. Therefore, the ink composition can improve the sharpness of an image and can display the aging time at a constant temperature with high reproducibility.

As the silicone oil, for example, amino-modified silicone oil, carboxy-modified silicone oil, polyether-modified silicone oil, alkyl-modified silicone oil, alkoxy-modified silicone oil, and fluorine-modified silicone oil can be used. Preferred silicone oils include, for example, amino-modified silicone oil, carboxy-modified silicone oil, polyether-modified silicone oil, and the like. As the amino-modified silicone oil, for example, a product name: KF-880 is commercially available from Shin-Etsu Chemical Co., Ltd. The carboxy-modified silicone oil is available, for example, as trade name: TSF-4770 (manufactured by Toshiba Silicone Co., Ltd.), and the polyether-modified silicone oil is available, for example, as trade name: Granol 115 (manufactured by Kyoeisha). The amount of the silicone oil used is 0.01 to 10% by weight based on the total amount of the ink composition. If the amount of the silicone oil is too large, it is not preferable because bleeding (bleeding) occurs on the film surface. On the other hand, if the amount is too small, the print formability is low, the print is formed in a crater shape, and the speed of discoloration and decoloration varies, and the reproducibility of aging time decreases, which is not preferable. The amount of the silicone oil used is preferably 0.2 to 4% by weight in the above range.

(Oil-soluble resin) By adding a resin to the above components (colorant, developer, solvent, silicone oil), it is possible to improve the adhesion (adhesion) of the ink to a printed material and to improve the ink composition. The viscosity can be adjusted. As resin,
Although not particularly limited, neutral to acidic resins are preferable, for example, aliphatic hydrocarbon resins, aromatic hydrocarbon resins,
A phenol resin, an acrylic resin, an amino resin, a ketone resin, or the like can be used. The resins can be used alone or in combination of two or more.

Examples of the aliphatic hydrocarbon resin include, for example,
Examples thereof include polyolefins such as polyethylene, polypropylene, polybutene and polyisobutylene, petroleum resins, terpene resins, chromanindene resins, and styrene resins. The aromatic hydrocarbon-based resin includes, for example, a xylene resin, a toluene resin, an alkylbenzene resin, and the like, and Nippon Petrochemical Co., Ltd. sells Nisseki Polymer 120 and the like.

As the phenol resin, a conventional phenol can be used. For example, rosin-modified phenol resin (trade name: Tamanol 35, manufactured by Arakawa Chemical Industries, Ltd.)
3), alkylphenol resin (Arakawa Chemical Industry Co., Ltd.)
(Trade name: Tamanol 100s).

The acrylic resin includes, for example, polyacrylate, polymethacrylate, polyacrylonitrile, polyacrylic acid, polyacrylamide and the like. As the amino resin, for example, a urea resin, a melamine resin, an amide resin and the like can be used.

Preferred resins include aromatic hydrocarbon resins and phenol resins, and phenol resins are most suitably used. The amount of the resin used is 0.2 to 50% by weight based on the total amount of the ink composition. If the content of the resin is too large, gelation may occur, while if it is too small, the adhesion to the print substrate is low. The preferred amount of resin used is 1
４０40% by weight.

In the ink composition of the present invention, if necessary, for example, additives such as a dye (pigment), a filler, a leveling agent, a viscosity modifier, a structural viscosity-imparting agent, a drying property-imparting agent, etc. Can be added.

(Production method) The ink composition of the present invention can be prepared by mixing the above-mentioned components (colorant, developer, solvent, silicone oil, and, if necessary, resin and additives). As a preferred preparation method, a colorant in a solvent,
For example, a method in which a developer and, if necessary, a resin are added and dissolved, and then silicone oil is added.

When the ink composition of the present invention is printed on the surface (external surface) of a can product (for example, can juice or canned product), the heat history of the can product under a certain temperature condition can be detected. Therefore, even a general consumer can easily visually recognize the aging time of the heat history of a can product kept at a constant temperature (for example, about 50 to 70 ° C.) such as a hot bender. Accordingly, the ink composition is useful for detecting the thermal history of a can product. The ink composition can also be used as an indicator for a sterilization treatment such as retort.

The ink composition of the present invention detects the thermal history at a constant temperature (for example, about 60 ° C.).
When used for labels such as canned products, it is hardly affected by heat (for example, room temperature or more and less than 50 ° C., preferably room temperature to 40 ° C.) in a distribution stage or the like. That is, there is almost no discoloration or decoloration at the distribution stage.

The ink composition can be printed by a conventional recording method such as an ink jet recording method and a recording method using a pen such as a fountain pen. In particular, the ink composition of the present invention is very useful because it can be easily printed by an inkjet recording method.

[0052]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. (Raw Materials) The following electron-donating compounds (coloring agents), electron-accepting compounds (developing agents), oil-soluble resins, solvents, and silicone oils were used as raw materials. (Colorant) Colorant 1: 3,3-bis (p-dimethylaminophenyl) -6-dimethylphthalide Colorant 2: 2- (N-phenyl-N-methylamino)-
6- (Np-tolyl-N-ethylamino) fluoran (Developer) Developer 1: methylene bisphenol Developer 2: 4,4′-ethylidene bisphenol Developer 3: 4,4 ′-( 2-ethylhexylidene) bisphenol (oil-soluble resin) Resin 1: Rosin-modified phenol resin (trade name: Tamanol 353, manufactured by Arakawa Industry Co., Ltd.) Resin 2: alkylphenol resin (trade name: Tamanol 100s, manufactured by Arakawa Industry Co., Ltd.) Solvent) Ethanol Ether: Propylene glycol monomethyl ether Toluene MIBK: Methyl isobutyl ketone (silicone oil) Silicone 1: Polyether-modified silicone oil (trade name: Granol 115, manufactured by Kyoeisha Chemical Co., Ltd.) Silicone 2: Carboxy-modified silicone oil (trade name: TSF-4770, Toshiba Silicon Silicone 3: Amino-modified silicone oil (trade name:
KF-880, manufactured by Shin-Etsu Chemical Co., Ltd.) (Others) Dye 1: Oil-soluble yellow dye (trade name: Spiron Yellow C-
GNH, manufactured by Hodogaya Chemical Co., Ltd. Dye 2: Oil-soluble red dye (trade name: Oil Red TR-)
71, manufactured by Chuo Gosei Co., Ltd.) Lithium chloride

(Test Method) The ink composition was evaluated by the following tests.

(Color difference retention rate test) Discoloration before and after the heating history display and start function was tested according to JIS Z 8729.
In the L * a * b * color system, evaluation is made by the color difference retention rate using the following equation (1). The lightness L * in L * a * b * when completely discolored and discolored is L1, the chromaticity a * in the red direction is a1, and the chromaticity b * in the yellow direction is b1. L * of a * b * is Ls, a * is as and b * is bs, and L * a * b * of the coating film after test is L
Assuming that t and a * are at and b * is bt, the discolored color difference retention ratio before and after the test is obtained using the following equation (1). Note that the higher the color difference retention rate, the less discoloration.

(Equation 1)

(Clearness) The sharpness of printing is visually determined. The criteria are as follows. ：: good print clarity ×: poor print clarity

(Adhesion test) A cellophane tape is stuck to the coating film printed on the printed material, and the coating film is pulled to evaluate the presence or absence of peeling of the coating film. The evaluation criteria are as follows. ：: No peeling ×: Peeling

(Example 1) A colorant, a developer and a resin were added to and dissolved in a solvent in the proportions shown in Table 1, and then an auxiliary agent such as silicone oil was added and stirred to prepare an ink composition. did. After converting this ink composition into an ink, using impulse jet (manufactured by Union Corporation),
It was printed on the bottom cover of the can, and under the storage conditions shown in Table 2, the start function and the detection function were evaluated based on the color difference retention rate, and the results are shown in Table 2. In addition, the print clarity and the adhesiveness between the can surface and the ink were evaluated, and the results shown in Table 3 were obtained. (Examples 2 to 4 and Comparative Example 1) An ink composition having the composition shown in Table 1 was prepared in the same manner as in Example 1, and a start function was prepared.
The detection function, print clarity, and adhesiveness were evaluated, and the results shown in Tables 2 and 3 were obtained. Example 5 An ink composition having the composition shown in Table 1 was used in Example 1.
It was prepared in the same manner as described above. A start function, a detection function, and an ink composition were prepared in the same manner as in Example 1 except that a charged jet printer (FX-2632, manufactured by Hitachi, Ltd.) was used.
The print clarity and adhesiveness were evaluated. The results are shown in Tables 2 and 3.

[0058]

[Table 1]

[0059]

[Table 2]

[0060]

[Table 3]

As can be seen from Tables 2 and 3, the ink compositions of Examples can form a coating film (printing) which changes color and discolors at a constant temperature (60 ° C.), and the reproducibility of the discoloring and decoloring speed is high. high. Also, the clarity of printing is excellent. further,
Has high adhesion. In Comparative Example 1, the color of the coating film was light at the center and dark at the outer edges, and there was variation in the reproducibility of the speed of discoloration and decoloration. In particular, the speed of discoloration at the center of the coating film is high.

[0062]

Since the ink composition of the present invention is composed of a colorant, a developer, a solvent, and a silicone oil, the print formed by the ink composition has a heat history under a constant temperature condition. Time can be displayed with high reproducibility, and a clear image can be formed. In addition, by combining the above components with a resin, it is possible to improve the above properties and the adhesiveness.

[Brief description of the drawings]

FIG. 1 is a view showing a state of a coating film formed by an ink composition of the present invention containing a silicone oil.

FIG. 2 is a diagram showing a state of a coating film formed of an ink composition containing no silicone oil.

[Explanation of symbols]

 Reference Signs List 1 coating film for printing 1a central part of coating film for printing 1b outer peripheral part of coating film for printing 2 painted surface of metal

Claims (5)

[Claims] An electron-donating compound, an electron-accepting compound,
A heat history indicating ink composition containing a solvent and silicone oil. 2. The silicone oil according to claim 1, wherein the silicone oil is at least one selected from amino-modified silicone oil, carboxy-modified silicone oil, polyether-modified silicone oil, alkyl-modified silicone oil, alkoxy-modified silicone oil, and fluorine-modified silicone oil. Ink composition. 3. The ink composition according to claim 1, comprising 0.01 to 10% by weight of a silicone oil. 4. The method according to claim 1, further comprising an oil-soluble resin.
4. The ink composition according to any one of Items 3 to 3. 5. An ink-jet ink composition using the ink composition according to claim 1. Description: