JPH03155984A - Thermal coloring composition - Google Patents

Abstract

PURPOSE:To obtain a thermal coloring composition with good dispersibility for a thermosensitive sheet free from uneven coating and excellent in coloring properties by containing 2-alkyl(or alkenyl)-1-hydroxylethylimidazoline. CONSTITUTION:For the purpose of obtaining a thermal coloring composition, 2-alkyl(or alkenyl)-1-hydroxylethylimidazoline is mixed with a coloring compound, developing compound and high molecular compound and, as occasion demands, with a filler heat-fusible compound and other additives and dispersed in an organic solvent. Preferably, however, the coloring compound and developing compound are pulverized and dispersed separately and the necessary quantities thereof are mixed together just before coating or printing. Preferably, also, 2-alkyl(or alkenyl)-1-hydroxylethylimidazoline exhibits its action as a dispersant and its alkyl or alkenyl group is C7-C23 in the number of carbon atoms, and its usage is within a range of 0.05-20% in the weight ratio to the thermal coloring composition to be dispersed. As a result, it is possible to obtain a thermal coloring composition facilitating the preparation of a thermosensitive sheet, in which uneven coating is hard to occur and coloring is in high concentration.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a heat-sensitive color forming composition. More specifically, the present invention relates to a heat-sensitive color-forming composition dispersed in an organic solvent with good dispersibility in order to provide a heat-sensitive recording sheet with no uneven coating and excellent color-forming properties.

Conventional technology A heat-sensitive recording material in which a leuco dye such as crystal violet lactone and a phenolic compound such as bisphenol A are coated on a support together with a vehicle is characterized by the fact that it does not generate noise, odor, smoke, etc. during recording. It is widely applied in the field of information equipment, such as printing by thermal printers used as terminals for electronic computers, thermal pen recorders for various medical devices such as electrocardiograms, recording by printers for industrial measuring equipment, and recording for thermal touch axes. ing.

In addition, recently, by taking advantage of its characteristics, its uses have been expanding, including use for ticket paper such as commuter passes and coupon tickets, cards, and labels. The requirements for heat-sensitive recording materials have also changed from one-time use to those that can be used many times, and the support for heat-sensitive recording materials has changed from paper to plastic films with good mechanical strength and water resistance. It is desired to convert to synthetic paper.

On the other hand, methods for forming a heat-sensitive recording coloring layer on a support range from full-surface coating, as seen in major fields such as heat-sensitive facsimile paper and printer recording paper, to partial printing and pattern printing using conventional printing machines. Printing methods are beginning to be used in various application fields. For this reason, coating conditions, especially the thickness of the coating layer, vary depending on the coating or printing method, and in order to adapt the coating amount to these conditions, it is necessary to increase the concentration of the heat-sensitive coloring component. This is necessary as a condition that is easy to deal with.

However, conventional dispersion in an organic solvent system involves separating the color-forming composition or color-developing compound and color-forming compound separately in an organic solvent alone or in a solution containing a resin (polymer compound) as a binder. However, if the solid content concentration is increased, not only will it result in high viscosity and gelation, making it impossible to obtain a good dispersion, but it will also cause streaks and spot patterns during coating or printing, and the density of the colored recorded image will decrease. It tends to be inadequate.

Problems to be Solved by the Invention There is a need for a heat-sensitive color-forming composition dispersed in an organic solvent with good dispersibility in order to provide a heat-sensitive sheet with no uneven coating and excellent color-forming properties.

Means for Solving the Problems The present inventors have completed the present invention as a result of various studies aimed at improving the above-mentioned problems.

That is, the present invention provides a heat-sensitive color-developing compound in which a color-developing compound and a color-developing compound that reacts with the color-developing compound to form a color under heating are dispersed in a vehicle mainly composed of an organic solvent and a polymer compound. The present invention provides a heat-sensitive color-forming composition characterized in that the composition contains 2-alkyl (or alkenyl)-1-hydroxylethylimidacillin.

The thermosensitive color-forming composition of the present invention is prepared in an organic solvent by 2-alkyl (
or alkenyl)-1-hydroxyethylimidazoline is mixed and dispersed with a color-forming compound, a color-developing compound, a polymer compound, a filler, a heat-fusible compound, and other additives as necessary, but the color-forming property It is preferable that the compound and the color developing compound are separately pulverized and dispersed, and then mixed in the required amount immediately before coating or printing.

2-Alkyl (or alkenyl)-1 used in the present invention
-Hydroxyethylimidazoline acts as a dispersant and the alkyl or alkenyl group has 07 to C23 carbon atoms.
It is preferable that

The amount used is the specific gravity of the heat-sensitive color forming composition to be dispersed! '($te 0.05%~20%, preferably 0.1%
It is used in the range of ~5%.

Specific examples of 2-□furkyl (or alkenyl)-1-hydroxyethylimidazoline include 2-octyl-1-hydroxyethylimidazoline, 2-decyl-
1-hydroxyethylimidazoline, 2-pentadecyl-1-hydroxyethylimidazoline, 2-nonadecyl-1-hydroxyethylimidazoline, 2-(1heptyl)-1-hydroxyethylimidazoline, 2-(1-
octyl)-1-hydroxyethylimidazoline, 2-
(1-nonel)-1 hydroxyethylimidacillin, 2
-(1decel)-1-hydroxyethylimidazoline,
Examples include 2-(2-nonyl-2-butenyl)-1-hydroxyethylimidazoline, which may be used alone or in combination.

organic solvent polymer compound for preparing the composition of the present invention,
Specific examples of the color forming compound, color developing compound and other additives include the following.

As the organic solvent for forming the vehicle, aromatic hydrocarbon solvents, naphthenic hydrocarbon solvents, and paraffinic hydrocarbon solvents may be used alone or in combination.

Representative examples of aromatic hydrocarbon solvents include benzene, toluene, xylene, ethylbenzene, ethyltoluene, etc.
Alternatively, a mixture thereof may be mentioned, and among them, it is preferable to use toluene and/or xylene.

Typical examples of naphthenic hydrocarbon solvents include cyclobencune, methylcyclopentane, 1゜1-dimethylcyclopentane, 1,3-dimethylcyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane, 1,2,4-trimethylcyclohexane. or a mixture thereof, among which it is preferable to use cyclohexane and/or ethylcyclohexane. Typical examples of paraffinic hydrocarbon solvents include n-hexane, n-hebutane, n-octane, n-
-nanones, isomers thereof, or mixtures thereof. In addition, when used as a mixed solvent, the boiling point of the main component of the solvent is preferably in the range of 80 to 140°C for gravure printing (or coating) compositions, and for screen printing (or coating) compositions. is preferably in the range of about 140°C to 200°C.

The polymer used is one that is soluble in organic solvents and can form a vehicle and form a film. Specific examples include polyvinyl chloride, polyacrylic, polyester, polycarbonate, polyurethane, polybutyral, epoxy resin, furan resin, and vinyl. Examples include toluene copolymers and rosin ester resins.

Examples of color-forming compounds include the following.

Rhodamine-βanilinolactam, rhodamine (p-nitroanilino)lactam as a xanthine compound,
2-dibenzylamino-6-diethylaminofluorane, 2-anilino-3-methyl-6-diethylamino-fluorane, 2-anilino-3-methyl-6-cyclohexylmethylaminofluorane, 2-anilino-3-)f Ru-6-bentyletheraminofluorane, 2-anilino-3-methyl-6-sibutylaminofluorane, 2
-p-chloroanilino-3-methyl-6-diethylaminofluorane, 2-p-fluoroanilino-3-methyl-6-diethylaminofluorane, 2-p-fluoroanilino-3-methyl-6-sibutylamino fluorane,
2-anilino-3-methyl-6-(p-1 luidinoethyl)aminofluorane, 2-p-)cyidino-3-methyl-6-diethylaminofluorane, 2-0-chloroanilino-6-diethylaminofluorane, 2- 0-chloroanilino-6-sibutylaminofluorane, 2-0-fluoroanilino-6-diethylaminofluorane, 2-
0-Fluoroanilino-6-sibutylaminofluorane, 2-m-chloroanilino-6-diethylaminofluorane, 2-anilino-3-methyl-6-piperidinofluorane, 2-anilino-3-methyl- 6-pyrrolidinofluorane, 2-m-trifluoromethylanilino-6-
Diethylaminofluorane, 2-dihexylamino-6
-aminofluorane, 2-butylamino-3-chloro-
6-diethylaminofluorane, 2-ethoxyethelamino-3-chloro-6-diethylaminofluorane, 2
-anilino-3-chloro-6-diethylaminofluoran, 2-diphenylamino-6-diethylaminofluoran, 2-anilino-3-methyl-6-siphenylaminofluoran, 2-phenyl-6-diethylaminofluoran, 2-chloro-3-methyl-6-diethylaminofluorane, 2-chloro-6-diethylaminofluorane, 2-methyl-6-diethylaminofluorane, 6-
3,3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (as a triarylmethane compound, such as dietheramin-1,2-benzfluorane)
Other names: crystal violet lactone), 3,3-bis(p-dimethylaminophenyl)phthalide, 3-(p
-dimethylaminophenyl)-3-(1,2-dimethylaminoindol-3-yl)phthalide, 3-(p-dimethylaminophenyl)-3-(2-methylindol-3-yl)phthalide, chromenes, etc. , 3-methyl-3-spirodinaphthopyran, 3-benzylspiro-dinaphthopyran, 3-methyl- as a spiropyran compound
naphtho-(3-methoxy-penz)spiropyran, 3-
Propyl-spiro-dibenzopyran, I, 3.3-1 Rimeter-0 6-nitro-8-methoxyspiro(indoline-2,2
-benzobilane), 1.3.3-) dimethyl 6'-nitrospiro (indoline-2,2-benzopyran), etc.
4,4'-bis-dimethylaminobenzhydrin benzyl ether as a diphenylmethane compound, N-halophenyl-leucoauramine, N-2,4,5-1-lichlorophenylleucoauramine, etc., as a thiazine compound Benzyl leucomethylene blue, p-nitrobenzyl leucomethylene blue, etc., as well as other bis-3,3-[bis-1,1-(1)-dimethylaminophenyl)ethylene-2]phthalide, bis-3,3-
Cbis-1,1-(p-dimethylaminophenyl)ethele/-2]-4,5,6゜7-titrachlorophthalide, bis-3,3-Cbis-1,1-(p-diethylamino phenyl)ethylene-2: ]-4,5,6,7-titrachlorophthalide, bis-3,3-C bis-1,1-
(p-dimethylaminophenyl)ethylene-2]-4
Divinyl group-containing phthalide derivatives such as (or 7)-nitrophthalide, 3,6-bis(dimethylamino)fluorene spiro(9,3')-6'-dimethylaminophthalide, 3,6-bis(diethylamino)fluorene spiro(9,3')-6'-dimethylaminophthalide, Fluorene compounds such as C7(9,3')-6'-diethylaminophthalide may also be used.

These color-forming compounds may be used alone or in combination.

Examples of color developing compounds include α-naphthol, β-naphthol, p-octylphenol, 4-octylphenol, pt-butylphenol, p~phenylphenol, and 1,1'-bis(p-hydroxyphenyl)propane. , 2.2'-bis(p-hydroxyphenyl)furopane, 2.2'-bis(p-hydroxyphenyl)butane, 1.1'-bis(p-hydroxyphenyl)cyclohexane, 4.4-thiobisphenol, 4.4 cyclo-hexylidene diphenol, 4.4'-x sulfonyl diphenol, 4.4'-sulfonyl-bis(2-allylphenol), 2.2'-bis(2゜5-syfurome-4 -Hydroxyphenyl)furopane, 4,4-isopropylidenebis(2-octylphenol), 2.2'
- Phenolic compounds such as methylenebis(4chlorophenol), benzyl p-hydroxybenzoate, ether p-hydroxybenzoate, dibenzyl 4-hydroxyphthalate, dimethyl 4-hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3. Examples include aromatic carboxylic acid derivatives such as 5-di-t-butylsalicylic acid and 3.5-di-α-methylbenzylsalicylic acid, aromatic carboxylic acids or polyvalent metal salts thereof.

Examples of other additives that may be used as necessary Examples of fillers include calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, talc, clay alumina, magnesium hydroxide, aluminum hydroxide, 7/l/minium oxide, Examples include barium sulfate, polystyrene resin, urea-formalin resin, etc.

Thermofusible compounds include animal and vegetable waxes, waxes such as polyethylene wax and synthetic wax, higher fatty acids, higher fatty acid amides, higher fatty acid metal salts,
Acetylated aromatic amines, aromatic ether compounds,
Examples include biphenyl derivatives that are solid at room temperature and have a melting point of about 80°C or higher.

Other lubricants such as zinc stearate, calcium stearate, aluminum stearate, various surfactants,
Antifoaming agents and the like are added as necessary.

The heat-sensitive color-forming composition of the present invention is prepared using the above-mentioned materials, for example, by the following method.

First, a color forming compound and a color developing compound are separately mixed in an organic solvent with 2-alkyl (or alkenyl)-1-hydroxyethylimidazoline, a polymer compound, and other additives using a dispersing machine such as a ball mill attritor or a sand mill. After pulverization and dispersion, the color-forming compound and the color-developing compound are mixed in a dry weight ratio of usually 1=1 to 1:10, and if necessary, a polymer compound solution and other additives are added. Additionally, a thermochromic ink composition of the present invention is obtained.

The thermosensitive color-forming composition of the present invention can be coated onto a support such as paper, plastic sheet synthetic paper, fiber sheet, etc. by a conventional coating method using a bar coater, roll coater, reverse coater, doctor coater, etc. Printing using methods such as , flexible printing, and silk screen is also possible. The heat-sensitive recording layer is formed as a film having a weight of 0.5 to 10 g/m2 on a dry weight basis.

Dispersibility (or fluidity) of a color-forming compound or a dispersion composition of a color-developing compound using 2-alkyl (or alkenyl)-1-hydroxyethylimidazoline and a heat-sensitive color-forming composition prepared using the same as a main component ) is good, and the thermosensitive recording layer formed on the support by means such as coating or printing has excellent thermochromic properties (coloring density).

EXAMPLES The present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

In the examples, "parts" indicate parts by weight.

Example 1 A mixture having the following composition was ground and dispersed for 1 hour using a sand mill to obtain a composition [A] and a composition [B].

Next, the components were mixed at the following mixing ratio to obtain a heat-sensitive color forming composition of the present invention.

Next, this ink composition was coated on a milky white polyester sheet at a rate of 20 g/m2 and dried to obtain a heat-sensitive color forming sheet.

Example 2゜4.4'-sulfonyl-bis(2-7lylphenol)
A heat-sensitive coloring composition of the present invention was obtained in the same manner as in Example 1, except that 2,2-bis(p-hydroxyphenyl)propane was used instead of 2,2-bis(p-hydroxyphenyl)propane, and toluene was used instead of xylene. A coloring sheet was produced.

Examples 3 to 7 Same as Example 1 except that 2-alkyl (or alkenyl)-1-hydroxyethylimidazolines shown in the following quality test clothing were used instead of 2-octyl-1-hydroxyethylimidazoline. A heat-sensitive color-forming composition of the present invention was obtained, and a heat-sensitive color-forming sheet was also produced.

Comparative Example 16 A comparative thermochromic composition was prepared in the same manner as in Example 1, except that 2-octyl-1-hydroxyethylimidazoline was not used, and a thermochromic sheet was also produced.

Comparative Example 2 A comparative thermochromic composition was prepared in the same manner as in Example 2, except that 2-octyl-1-hydroxyethyl imidazoline was not used, and a thermochromic sheet was also produced.

A quality test was conducted using these heat-sensitive color-forming compositions and heat-sensitive color-forming sheets of the present invention and for comparison.

7- -19 1) Fluidity The flow state when the container was tilted was investigated.

○: Flowing Δ: Slowly flowing ×: Little or no movement 2) Color density A thermosensitive color forming sheet made with a commercially available thermal printer (manufactured by Ishida Koki, D-805F) was printed, and the color density was measured using a Macbeth reflection densitometer RD. -Value measured with type 914.

3) Coating bugs The coated area of the produced heat-sensitive coloring sheet was observed to check for the occurrence of bumps, spots, and streaks.

○: Hardly or not at all △: or N Conspicuously ×: Frequently recognized From the above quality tests, it is clear that the heat-sensitive color-forming composition of the present invention has good fluidity, and it is difficult to coat the prepared heat-sensitive color-forming sheet. The finish is good and the color density is high.

Effects of the Invention A heat-sensitive color-forming composition that has good fluidity, is less likely to cause uneven coating, and facilitates the preparation of a heat-sensitive sheet with high color density was obtained.

Claims (1)

[Claims] 1. A thermosensitive color-forming composition comprising a color-developing compound and a color-forming compound that reacts with the color-developing compound to form a color under heating, dispersed in a vehicle mainly composed of an organic solvent and a polymer compound, 2. - A thermosensitive color-forming composition characterized by containing an alkyl (or alkenyl)-1-hydroxyethylimidazoline.