JPH064796B2 - Thermosensitive color ink composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a phenolic compound constituting a thermosensitive color developing agent in a vehicle prepared by dissolving a specific resin in a specific solvent. By dispersing each leuco dye, gravure printing is possible, and it adheres well not only to paper but also to synthetic paper, plastic film, etc. without an anchor coat, and has good storage stability. It relates to an ink composition.

(Prior art) Leuco dye such as crystal violet lactone,
Since a thermal recording material in which a phenolic compound such as bisphenol A is coated on a support together with a vehicle has the characteristic that noise, offensive odor, smoke, etc. do not occur during recording, a thermal printer used as a terminal of a computer is used. Printing, thermal pen recorders for various medical devices such as electrocardiograms, recording by printers of industrial measuring devices,
Alternatively, it is widely applied in the field of information equipment such as recording for thermal facsimile.

In addition, recently, by taking advantage of its features, its applications are expanding, such as the use for wrapping paper such as commuter passes and coupons, cards and labels. The demand for thermal recording materials has changed from one-time use to many-time use, and the support for heat-sensitive recording materials is made from paper to mechanical strength,
It is desired to convert it to a plastic film or synthetic paper having good water resistance.

On the other hand, a two-liquid separation type thermosensitive color ink composition capable of pattern printing by gravure printing is disclosed in JP-A-56-325.
Vehicle obtained by dissolving a vinyltoluene copolymer resin or a rosin ester resin in a naphthenic hydrocarbon solvent having a boiling point of 50 to 150 ° C., which is inert to phenolic compounds and leuco dyes as disclosed in Japanese Patent Laid-Open No. 64 Some use. However, although this thermosensitive color-forming ink composition has a good adhesiveness to paper, it has a drawback that it has a low adhesiveness to a plastic film or synthetic paper and the stability of the ink is poor.

(Problems to be Solved by the Invention) The present invention improves the above-mentioned various drawbacks, enables gravure printing, and adheres not only to paper but also to synthetic paper, plastic film, etc. without an anchor coat, and is storage stable. A two-liquid separation type heat-sensitive color-forming ink composition having good properties is provided.

[Structure of Invention]

(Means for Solving Problems) In the present invention, a solution A in which a phenolic compound is dispersed in a vehicle, and a leuco dye that reacts with the phenolic compound under heating to develop a color are dispersed in the vehicle. Which is a combination of an aromatic hydrocarbon solvent, a naphthene-based hydrocarbon solvent and / or a paraffin-based hydrocarbon solvent, and styrene as a main component and acrylic acid. A two-liquid separation type heat-sensitive color-forming ink composition comprising an acrylic resin obtained by dissolving one or more monomers such as an alkyl ester, an alkyl methacrylic acid ester, and vinyl acetate in a copolymer.

In the present invention, as the phenolic compound, known compounds are used. Examples of such a phenolic compound include phenol, o-cresol, p-cresol and p.
-Ethylphenol, tert-butylphenol,
2,6-di-tert-butyl-4-methylphenol, nonylphenol, dodecylphenol, styrenated phenol, 2,2'-methylene-bis- (4-methyl-6-tert-butylphenol), α-naphthol, β -Naphthol, hydroquinone monomethyl ether, guaiacol, eugenol, p-chlorophenol, p-bromophenol, o-bromophenol, o
-Chlorophenol, 2,4,6-trichlorophenol, o-phenylphenol, p-phenylphenol, p- (p-chlorophenyl) phenol, o- (o
-Chlorophenyl) phenol, salicylic acid, methyl p-oxybenzoate, butyl p-oxybenzoate, octyl p-oxybenzoate, dodecyl p-oxybenzoate,
Catechol, hydroquinone, resorcin, 3-methylcatechol, 3-isopropylcatechol, p-tert
-Butylcatechol, 2,5-di-tert-butylhydroquinone, 4,4'-methylenediphenol, bisphenol A, 1,2-dioxynaphthalene, 2,3-dioxynaphthalene, chlorcatechol, promocatechol, 2 , 4-dihydroxybenzophenone, phenolic phthalein, o-cresolphthalein, methyl protocatechuate, ethyl protocatechuate, propyl protocatechuate, octyl protocatechuate, dodecyl protocatechuate, pyrogallol, oxyhydroquinone , Phloroglucin, 2,4,6-trioxymethylbenzene, 2,3,4-trioxyethylbenzene, gallic acid, methyl gallate, ethyl gallate, propyl gallate, butyl gallate, hexyl gallate, octyl gallate ， Death Child dodecyl, cetyl gallate,
It is a compound having a phenolic hydroxyl group such as stearyl gallate, 2,3,5-trioxynaphthalene, tannic acid, and phenol resin.

Known leuco dyes can be used in the present invention. Examples of such leuco dyes include triphenylmethane compounds such as crystal violet lactone and malachite green lactone, 1,2-benz-6-diethylaminofluorane, and the like. The fluoran dyes, auramine dyes such as N-benzoyl auramine, phenothiazine dyes, and spiropyran dyes such as leuco dyes can be used.

As the vehicle-forming solvent used in the present invention, a mixed solvent comprising an aromatic hydrocarbon solvent and a naphthene-based hydrocarbon solvent and / or a paraffin-based hydrocarbon solvent is used. Representative examples of the aromatic hydrocarbon solvent include benzene, toluene, xylene, ethylbenzene and the like, or a mixture thereof, and among them, it is preferable to use toluene and / or xylene. Further, as typical examples of the naphthene-based hydrocarbon solvent, cyclopentane, methylcyclopentane, 1,1-dimethylcyclopentane, 1,3-dimethylcyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane,
Examples include 1,2,4-trimethylcyclohexane and the like, or a mixture thereof, and among them, cyclohexane and / or ethylcyclohexane are preferably used. As a typical example of the paraffinic hydrocarbon solvent,
Examples thereof include n-hexane, n-heptane, n-octane, n-nonane, isomers thereof, or a mixture thereof. The aromatic hydrocarbon solvent and the naphthenic hydrocarbon solvent and / or the paraffinic hydrocarbon solvent are different depending on their types.
It is preferable to use the naphthene hydrocarbon solvent and / or the paraffin hydrocarbon solvent in a ratio of 3/7 to 8/2 (weight ratio). Further, 5 wt% or less of a chlorine-based hydrocarbon, such as trichloroethylene, perchlorethylene, or diethylene chloride, can be added to these mixed solvents based on the total amount. In addition, alcohol system,
Mixing of ketone-based, ester-based, or ether-based solvents causes solvent coloring of leuco dyes and should be strictly avoided.

The boiling point of the solvent that is the main component of the mixed solvent is 50 to 1
It is preferably in the range of 50 ° C, and more preferably 80 to 1
It is preferably in the range of 40 ° C. When the boiling point of the solvent, which is the main component of the mixed solvent, is less than 50 ° C, drying tends to occur quickly and the evaporation of the solvent tends to increase the viscosity to cause plate jams. There is a tendency for unevenness to occur and the printing speed to slow down.

In the present invention, an acrylic resin is used as the vehicle resin. As such an acrylic resin, styrene is the main component, and acrylic acid alkyl ester,
One obtained by copolymerizing one kind or two or more kinds of other monomers such as other alkyl methacrylate, vinyl acetate and the like is preferably used.

In the present invention, as the vehicle, a vehicle prepared by dissolving the acrylic resin in the mixed solvent at room temperature or by heating is used.

The heat-sensitive color-forming ink composition of the present invention comprises solution A in which the above phenolic compound is dispersed in the above vehicle, and solution B in which the above leuco dye is dispersed in the above vehicle. Solution A is obtained by adding the above phenolic compound to the above vehicle and kneading with a disperser such as a ball mill or a paint conditioner.

Solution B can also be obtained by adding the above leuco dye to the above vehicle and kneading in the same manner as solution A.

If necessary, calcium carbonate, precipitated barium sulfate, alumina,
Inorganic fillers such as acid clay, silica gel, clay, magnesium carbonate, silicon oxide, paraffin wax solid at room temperature, polyethylene wax, carnauba wax,
Waxes such as microcrystalline wax and amide wax, phthalates, citrates,
A plasticizer such as adipic acid ester, an anion, a nonionic or a cationic surfactant can be added.

The thermosensitive color-forming ink composition of the present invention is applied or printed on a substrate such as paper, plastic film, and synthetic paper in the order of solution A and solution B, or solution B and solution A in that order to form two or more layers. Or, apply or print liquid A on one of these substrates and liquid B on the other, and then overlay these substrates so that the two coated or printed surfaces are in contact. Good. As a method of coating or printing, a method using a coating machine such as a roll coater, a reverse coater, a doctor coater, etc., which is similar to the conventional method, or a method using gravure printing is also possible. Therefore, in addition to solid printing using a conventional coating machine, pattern printing by gravure printing is also possible.

(Examples) Hereinafter, the present invention will be described with reference to Examples. In the examples, "part" means "part by weight" and "%" means "% by weight".

Example 1 Ink A Bisphenol A 30 parts Styrene-butyl methacrylate copolymer (molecular weight about 70,000, Tg 103 ° C) 13.5 parts Toluene 31.5 parts Methylcyclohexane 25 parts Ink B Fluoran leuco dye "TH107" (preserved) Tsuchiya Chemical Industry Co., Ltd., trade name 10 parts Styrene-butyl methacrylic acid copolymer (molecular weight about 70,000, Tg 103 ° C.) 18 parts Toluene 52 parts Methylcyclohexane 20 parts Ink A and Ink B of the above composition are respectively magnetized. It was obtained by kneading in a ball mill for 24 hours, and a mixed solvent of toluene / methylcyclohexane = 1/1 (weight ratio) was used as a diluent.
After adjusting the time to 2 seconds, a two-liquid separation type thermosensitive coloring ink composition was obtained. Of the resulting two-liquid separation type thermosensitive color ink composition, ink A after viscosity adjustment was solid-printed on a milk white polyester film by a gravure printing method so that the dry coating amount was about 2 g / m ^2, and then, Ink B after viscosity adjustment after solid printing is applied by gravure printing method with a dry coating amount of about 1 g /
The pattern was printed so as to have a size of m ² . When the obtained thermosensitive coloring film was heated, a clear black pattern was exhibited. Table 1 shows the results of evaluation of the presence or absence of color development in Ink B, the storage stability of Inks A and B, the adhesiveness to the film, the thermosensitive color development, and the presence or absence of background stains.

Example 2 A two-part liquid consisting of ink A and ink B whose viscosity was adjusted in the same manner as in example 1 except that benzyl p-oxybenzoate was used instead of bisphenol A and n-heptane was used instead of methylcyclohexane. A separate type thermosensitive color ink composition was obtained. Ink B after viscosity adjustment is dried on opaque polyester film by gravure printing and the amount is about 2g
/ M ² solid printing, and further, the viscosity A of ink A after gravure printing was applied by a gravure printing method to a coating amount of about 1
Printing was carried out in stripes so as to obtain g / m ² . When the obtained thermosensitive color-developing film was heated by a heating roll, it appeared black in a stripe shape. At this time, Example 1
The results of the same evaluations as in Table 1 are shown in Table 1.

Example 3 Ink A Bisphenol A 20 parts Styrene-ethyl acrylate copolymer (molecular weight about 60,000, Tg97 ° C.) 20 parts Toluene 30 parts Methylcyclohexane 30 parts Ink B Fluoran-based leuco dye “TH106” (Hodogaya Chemical Co., Ltd. ), Trade name) 20 parts Styrene-butyl acrylate copolymer (molecular weight about 60,000, Tg97 ° C) 20 parts Toluene 30 parts Ethylcyclohexane 30 parts Ink A and ink B having the above composition are used.
Toluene / ethylcyclohexane = 1/1 as diluent
A thermosensitive color forming film was obtained in the same manner as in Example 1 except that the mixed solvent (weight ratio) was used, and the same evaluation as in Example 1 was performed. The coloration due to heating was clear black.

Comparative Example 1 Table 1 shows the results of evaluation performed in the same manner as in Example 3 except that toluene was used instead of ethylcyclohexane.

Comparative Example 2 Table 1 shows the results of evaluation performed in the same manner as in Example 3 except that 2-butanone was used instead of ethylcyclohexane.

Comparative Example 3 The evaluation was performed in the same manner as in Example 3 except that ethylcyclohexane was used instead of toluene, but the acrylic resin did not dissolve in ethylcyclohexane.

Comparative Example 4 Same as Example 3 except that polymerized rosin pentaerythritol ester “Pentaline C” (Hercules, trade name) was used in place of the styrene-ethyl acrylate copolymer, and ethylcyclohexane was used in place of toluene. Table 1 shows the results of the evaluation.

Comparative Example 5 Same as Example 3 except that a vinyltoluene butadiene resin “Pryolite VT” (manufactured by Goodyear Co., Ltd.) was used in place of the styrene-ethyl acrylate copolymer, and ethylcyclohexane was used in place of toluene. Table 1 shows the results of the evaluation.

Comparative Example 6 Results of evaluation in the same manner as in Example 3 except that a chlorinated polyolefin resin “Super Clone 602” (manufactured by Sanyo Kokusaku Pulp Co., Ltd., trade name) was used in place of the styrene-ethyl acrylate copolymer. Is shown in Table 1.

Comparative Example 7 The same as Example 3 except that an ethylene-vinyl acetate copolymer "Evaflex 250" (trade name, manufactured by Mitsui DuPont Polychemical Co., Ltd.) was used in place of the styrene-ethyl acrylate copolymer. Table 1 shows the evaluation results.

Examples 4 and 5 Instead of "TH107", "Red DCF" (trade name, Example 4 manufactured by Hodogaya Chemical Co., Ltd.) and "CVL"
When a heating test was performed in the same manner as in Example 1 except that (Hodogaya Chemical Co., Ltd., trade name, Example 5) was used, a bright red color and a vivid blue color were respectively formed in a pattern. .

〔The invention's effect〕

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a two-liquid separation type thermosensitive coloring ink composition capable of gravure printing, sufficiently adhered to not only paper but also plastic film, synthetic paper, etc. without an anchor coat, and having good storage stability. Became.

Claims (1)

[Claims] 1. A liquid prepared by dispersing a phenolic compound in a vehicle, and a leuco dye which reacts with the phenolic compound under heating to develop a color B in the vehicle.
Consisting of a liquid, wherein the vehicle is a mixed solvent consisting of an aromatic hydrocarbon solvent and a naphthene hydrocarbon solvent and (or) paraffin hydrocarbon solvent, styrene as a main component, and an acrylic acid alkyl ester, A two-liquid separation type thermosensitive color-forming ink composition, which is prepared by dissolving an acrylic resin obtained by copolymerizing one or more monomers such as alkyl methacrylic acid and vinyl acetate.