JPS60184879A - Thermal recording material - Google Patents

Abstract

PURPOSE:To prevent ground fogging from occuring due to an unrequired color forming reaction induced by heat, a solvent or the like, by a method wherein a blocked phenol compound obtained by a reaction of an isocyanate compound with a phenol compound is used as a color developer. CONSTITUTION:A blocked phenol compound obtained by the reaction of an isocyanate compound and a phenol compound is used as a color developer in a thermal recording material which comprises an electron-donative colorless dye precursor and a color developer capable of developing the color of the dye precursor when being heated. The blocked phenol compound is inactive at normal temperature, but when being heated, it is dissociated back into the isosyante compound and the phenol compound. In use of the thermal recording material, the dye precursor and the blocked phenol compound in coexistence are heated, and the phenol compound reproduced through dissociation of the blocked phenol compound is brought into color forming reaction with the dye precursor, thereby recording an image. The blocked phenol compound is preferably a compound of general formula ( I ) or (II), wherein R1 is subst. or unsubst. benzene ring, R2 is a phenol compound residue, R4 is a phenol compound residue, R5 is a subst. or unsubst. phenyl, and n is an integer of 1-4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording material using a novel coloring method.

Generally used heat-sensitive recording materials are two-component color systems using two types of heat-reactive compounds, in particular an electron-donating, usually colorless or light-colored dye precursor, and an electron-accepting pongee coloring agent. The one used is representative. Such a heat-sensitive recording material V'i, a dye precursor, a color developer and a sound VC,
A heat-sensitive recording layer is provided on a support, which is dispersed in the form of imitative particles and separated from each other by a binder, etc., and the dye precursor and dye precursor are separated by heating with a thermal head, heat exchanger, laser beam, etc. The color developer melts and comes into contact, causing an instantaneous color reaction.
A recorded image can be obtained on the heated part, and it is
-4160, Japanese Patent Publication No. 45-14039, etc. Such heat-sensitive recording materials have the advantages of being able to obtain recorded images with relatively simple equipment, being easy to maintain, and producing no noise. It is used in a wide range of fields such as automatic ticket vending machines, labels, and ticket vending machines.

However, since two types of heat-reactive compounds coexist on the same surface, if stored for a long time in a particularly high temperature place, the scalp (
As a result, the coloring reaction gradually progresses and a phenomenon called smudge (caprin) occurs as a result of some melting due to heat in the uncolored area (uncolored area).Also, due to the adhesion of solvents such as alcohol, amine developer of diazo photosensitive paper, etc. As a result of partial dissolution by the solvent, a coloring reaction occurs, which also produces capri.Methods such as multi-layer coating and addition of desensitizers have been used to compensate for these drawbacks, but none of them have yet completely failed. No satisfactory method has been found.

In order to improve all of the above-mentioned drawbacks, the present inventors have conducted intensive research and found that a heat-sensitive recording material comprising an electron-donating colorless dye precursor and a color developer capable of coloring the electron-donating colorless dye precursor when heated. 7if the color developer is a blocked phenol compound obtained by the reaction of an incyanate compound and a phenol compound - the above-mentioned drawbacks can be improved by a heat-sensitive recording material based on a novel color development method characterized by: did it.

The blocked phenolic compound is an incyanate compound (
-Net) and a phenol compound (-OH) and is an addition compound obtained by the reaction of -Neo +
It is a compound with a urethane bond such as HO-→-NHCOO-. The blocked phenol compound is inactive at room temperature, but has the characteristic of dissociating into the original incyanate compound and the phenol compound when heated. In the heat-sensitive recording material according to the present invention, an electron-donating colorless dye precursor and a blocked phenol compound are allowed to coexist and heated, whereby the dissociated and regenerated phenol compound and the electron-donating colorless dye precursor undergo a coloring reaction. A recorded image is obtained. Since the blocked phenol compound exists in an inactive state unless the amount of heat necessary for dissociation is applied, the capri phenomenon on the background due to unnecessary color reaction caused by heat, solvent, etc. does not occur at all.

The blocked phenolic compound according to the present invention has the general formula (
1) and (It) are preferred.

1 几, (NHCOR,). (1) (However, 几 represents a substituted or unsubstituted benzene ring, R2 represents all phenol compound residues, and n represents an integer from 1 to 4.] 1 kL4-E 0CNH-R5) 2 (old ( However, R4
represents a phenol compound residue, and It5 represents a substituted or unsubstituted phenyl group. ) These blocked phenol compounds can be easily obtained by reacting a phenol compound and a predetermined amount of an incyanate compound, which is a blocking agent, in an inert solvent at a temperature from room temperature to 160°C with the addition of a catalyst. It is. The phenol compound is selected from those that cause a color-forming reaction with the electron-donating colorless dye precursor, and the incyanate compound is preferably an aromatic incyanate compound in order to lower the dissociation temperature of the blocked phenol compound.

Next, specific examples of the phenol compound and incyanate compound used to obtain the blocked phenol compound represented by the general formulas (1) and (n) will be shown.

For example, the blocked phenol compound represented by general formula (1) includes phenol, p-chlorophenol, p-
Nitrophenol, 0-methylphenol, m-methylphenol, p-methylphenol, p-tert-butylphenol, p-octylphenol, methoxy 7
ethyl, p-phenylphenol, thymol, methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, isoglobil p-hydroxybenzoate, butyl p-hydroxybenzoate, p-hydroxy Phenol compounds such as benzyl benzoate and diphenylmethane diisocyanate, 3,3'-
dimethyl-4,4'-diphenyl diisocyaner), 4
．． 4'-diphenyl diisocyanate, 2.4-)lylene diisocyanate, 2.6-lylene diisocyanate, xylene diisocyanate, phenyl inocyanate, p-bromophenyl isocyanate, O-chlorophenylisocyanate, m-chlorophenylisocyanate-1, 1)-Ob7xnylinocyanate, 2,
5-dichlorophenylisocyanate, 2.5-dimethylphenylisocyanate, 0-ethoxyphenylisocyanate, p-ethoxyphenylisocyanate, p
-) Lylisocyanate, m-nitrophenyl isocyanate, p-7 enylene diisocyanate, 2,5-dimethyl-1)-phenylene diinocyanate, and the like. Also, the general formula (
The blocked phenol compound represented by II) is 1,
1-bis(p-hydroxyphenyl)furopane, 2,2
-bis(p-hydroxyphenyl)propane, 1.1-
Bis(p-hydroxyphenyl)pentane, 1.1-bis(p-hydroxyphenyl)cyclohexane, 4.4
'-thiobis(p-hydroxyphenol), 4.4'
-thiobis(6-tert-butyl-m-cresol)
, 2゜phenol compounds such as 2-bis(p-hydroxyphenyl)butane and bis(4-hydroxyphenyl)sulfone and phenyl incyanate, p-bromophenyl isocyanate, p-chlorophenylisocyanate,
In-chlorophenylisocyanate, 0-chlorophenylisocyanate, t, -1-12゜5-dimethylphenylisocyanate), 2,5-dichlorophenylisocyanate, 0-methoxyphenylyne/anate, p-methoxyphenylisocyanate, p-ethoxyphenyl Isocyanate, m-nitrophenyl isocyanate, p
- Obtained by reaction with incyanate compounds such as nitrophenyl incyanate, 0-tolyl isocyanate, m-tolyl isocyanate, and p-tolyl isocyanate.

Examples of the electron-donating colorless dye precursor include triphenylmethane-based, fluoran-based, diphenylmethane-based, thiazine-based, and spiropyran-based compounds. For example, crystal violet lactone, 3-diethylamino-
7-Methylfluorane, 3-diethylami/-6-chloro-7-methylfluorane, 3-diethylami/-6-
Methyl-7-chlorofluorane, 3-diethylamide/-
7-anilinofluorane, 3-diethylamino-7-(
2-chloroanilino)fluoran, 3-dibutylamino-7-(2-chloroanilino)fluoran, 3-diethylamino-7-(3-chloroanilino)fluoran, 3
-diethylamino-6-methyl-7-anilinofluorane, 3-(N-ethyl-p-)luidino)-6-methyl-7-anilinofluorane, 3-(N-methylcitalohexylamino)- Examples include 3-methyl-7-anilinofluorane and 3-piperidino-3-methyl-7-anilinofluorane. These can be used alone or in combination.

Examples of binders include starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, water-soluble binders such as styrene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, and styrene. - Latex water-insoluble binders such as butadiene copolymer, acrylonitrile-butadiene copolymer, acrylic methyl-butadiene copolymer, and the like.

Examples of pigments include diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, urea-formalin resin, and the like.

Although paper is mainly used as the support for the heat-sensitive recording material of the present invention, any of various nonwoven fabrics, plastic films, synthetic papers, metal foils, etc., or composite sheets made of combinations thereof can be used.

Hereinafter, examples will be shown and the entire history of the present invention will be explained in detail.
The present invention is not limited to this example.

Example 1 3-diethylamino-6-methyl-7-anilinofluorane was dispersed in a ball mill for 24 hours with 30 f of a 1-2% polyvinyl alcohol aqueous solution. On the other hand, 4-t-butylphenyl = he-phenylcarbame) 35ft-2%
It was dispersed for 24 hours in a ball mill with polyvinyl alcohol aqueous solution 1052. After mixing these dispersions, 125f of a 20t dispersion of silicon oxide and 220tk of a 10t aqueous solution of vinyl alcohol were added as pigments and thoroughly stirred to prepare a coating solution.

The coating solution was applied to a base paper having a basis weight of 559/m'' using a Mayer parr, dried, and processed using a super calender to obtain a heat-sensitive recording material.

Example 2 Thermal reaction was carried out in the same manner as in Example 1, except that 2,4-bis(4-1-butylphenoxycarbonylamino)toluene was used instead of 4-t-butylphenyl-N-phenylcarbamate in Example 1. Obtained recording materials.

Example 3 Example 1 except that 2,2-bis(p-N-phenylrupamoyloxyphenyl)furopane was used instead of 4-t-butylphenyl-N--ydynylcarbamate in Example 1. A heat-sensitive recording material was obtained in the same manner as above.

Example 4 When the heat-sensitive recording materials obtained in Examples 1 to 3 were printed using a heat-sensitive facsimile tester, clear recorded images were obtained in all cases.

In addition, when the uncolored areas of each heat-sensitive recording material were stored in an atmosphere at 80°C for 2 hours, coloring phenomenon (fogging) occurred in the uncolored areas.
was not seen.

Claims (1)

[Claims] In a heat-sensitive recording material comprising an electron-donating colorless dye precursor and a color developer capable of coloring the electron-donating colorless dye precursor when heated, C1 the color developer reacts with an incyanate compound and a phenol compound. A heat-sensitive recording material characterized by being a blocked phenol compound obtained by.