JP3170082B2 - Thermal recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material having excellent heat responsiveness and preservability of a color image.

[0002]

2. Description of the Related Art Thermal recording materials utilizing a thermal reaction between an aromatic imino compound and an aromatic isocyanate compound are disclosed in JP-A-58-38733, JP-A-58-54085 and JP-A-58-54085.
-262686 and the like. These heat-sensitive recording materials are excellent in the preservability of the recorded image, but the stability of the coloring performance of the heat-sensitive recording material before use is not sufficient.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material in which the stability of color development performance before use is further added to the conventional characteristics of excellent preservation of recorded images.

[0004]

Means for Solving the Problems As a result of intensive studies to solve these problems, the present inventors have used substituted or unsubstituted 1,3-diimino-isoindoline as an aromatic imino compound, In the heat-sensitive recording material utilizing the thermal reaction of the imino compound and the aromatic imino compound, by containing zinc carbonate, the storage stability of the color-formed image is not changed, and the color-forming performance of the heat-sensitive recording material before use is reduced. It was found to be a specific improvement.

In the present invention, zinc carbonate is added to the heat-sensitive recording layer.

The zinc carbonate uses a substituted or unsubstituted 1,3-diimino-isoindoline as an aromatic imino compound, and a color-forming performance before use of a thermosensitive recording material using this compound and an aromatic isocyanate compound. Is considered to be because the substituted or unsubstituted 1,3-diimino-isoindoline is affected by the acidic substance contained in the support or the color-forming layer, and has an effect of blocking the deterioration. To prevent the action of the acidic substance, a basic compound may be added. However, the zinc carbonate of the present invention has been found to be more effective than a general basic compound, and the present invention has been achieved.

[0007] In the present invention, zinc carbonate is usually added in an amount of 10% or more based on a specific aromatic imino compound.
Preferred amounts are 50-500%. If the addition amount is 10% or less, the effect of white paper stability is not sufficient, and if it exceeds 500%, the effect of inhibiting color development becomes significant. Therefore, the amount is specified, but there is no particular obstacle to white paper stability.

[0008] The aromatic isocyanate compound used in the present invention is a colorless or light-colored solid which is solid at ordinary temperature. For example, one or more of the following compounds are used.

2,6-dichlorophenyl isocyanate, p-chlorophenyl isocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1,3-dimethylbenzene-4,6-diisocyanate, 1,4-dimethylbenzene-2 , 5-Diisocyanate, 1-ethoxybenzene-2,4-diisocyanate, 2,5-dimethoxybenzene-1,4-diisocyanate, 2,5-diethoxybenzene-1,4
-Diisocyanate, 2,5-dibutoxybenzene-
1,4-diisocyanate, azobenzene-4,4'-
Diisocyanate, diphenyl ether-4,4'-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, naphthalene-2,6-diisocyanate, naphthalene-2,7-
Diisocyanate, 3,3'-dimethylbiphenyl-
4,4'-diisocyanate, 3,3'-dimethoxy-
4,4'-diisocyanate, diphenylmethane-4,
4'-diisocyanate, diphenyldimethylmethane-
4,4′-diisocyanate, benzophenone-3,
3'-diisocyanate, fluorene-2,7-diisocyanate, anthraquinone-2,6-diisocyanate, 9-ethylcarbazole-3,6-diisocyanate, pyrene-3,8-diisocyanate, naphthalene-
1,3,7-triisocyanate, biphenyl-2,
4,4′-triisocyanate, 4,4 ′, 4 ″ -triisocyanate-2,5-dimethoxytriphenylamine, p-dimethylaminophenylisocyanate, tris (4-phenylisocyanate) thiophosphate and the like.

[0010] These aromatic isocyanate compounds are
If necessary, phenols, lactams, oximes and the like may be used in the form of a blocked isocyanate, which is an addition compound, or a diisocyanate dimer such as 1-methylbenzene-2,4-diisocyanate. It may be used in the form of isocyanurate, which is a dimer or trimer, or may be used as a polyisocyanate added with various polyols or the like.

The aromatic imino compound used in the present invention is a substituted or unsubstituted 1,3-diimino-isoindoline which is a colorless or pale-colored compound which is solid at room temperature. Preferred specific examples are shown below.

1,3-diiminoisoindoline, 1,3
-Diimino-6-chloroisoindoline, 1,3-diimino-4,5,6,7-tetrachloroisoindoline,
1,3-diimino-4,5,6,7-tetrabromoisoindoline, 1,3-diimino-4,5,6,7-tetrafluoroisoindoline, 1,3-diimino-4,
5,7-trichloro-6-methylmercaptoisoindoline, 1,3-diimino-6-methoxyisoindoline, 1,3-diimino-6-cyanoisoindoline,
1,3-diimino-4,7-dithia-5,5,6,6-
Tetrahydroisoindoline, 1,3-diimino-5
6-dimethyl-4,7-pyradiisoindolin and the like.

The heat-sensitive recording material according to the present invention may contain a heat-fusible substance in order to improve its thermal response. In this case, those having a melting point of 80 to 140 ° C are preferable. Specific examples include N-hydroxymethylstearic acid amide, stearic acid amide, palmitic acid amide, ethylenebisstearic acid amide, methylenebishydrogenated tallow fatty acid amide, paraffin wax, microcrystalline wax, polyethylene wax, and carnauba wax. Naphthol derivatives such as 2-benzyloxynaphthalene, biphenyl derivatives such as p-benzylbiphenyl and 4-allyloxybiphenyl, 1,2-bis (3-methylphenoxy) ethane,
Polyether compounds such as 2,2'-bis (4-methoxyphenoxy) diethyl ether and bis (4-methoxyphenoxy) ether; ester derivatives such as diphenyl carbonate, dibenzyl oxalate, and oxalic acid (p-methylbenzyl) ester; be able to. These heat-fusible substances can be used alone or in combination of two or more. In order to obtain sufficient thermal responsiveness, it is preferable to use 20 to 250% by weight based on the aromatic isocyanate compound.

In the present invention, a coloring component of a basic leuco dye and an acidic phenol compound used in a usual thermosensitive recording material is used simultaneously with a coloring component of a specific aromatic imino compound and an aromatic isocyanate compound. can do.

The basic leuco dye used in the heat-sensitive recording material of the present invention is not particularly limited as long as it is generally used in pressure-sensitive recording paper or heat-sensitive recording material.
Specific examples are as follows. Crystal violet lactone, 3- (p-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl)
Phthalide, 3,3-bis (2-methyl-1-octyl-
3-indolyl) phthalide, 3- [4-diethylamino-2-ethoxyphenyl] -3- (2-methyl-1-octyl-3-indolyl) -4-azaphthalide, 3,3
-Bis (2-methyl-1-octyl-3-indolyl)
-4-azaphthalide, 3-cyclohexylamino-6-
Chlorofluorane, 3-diethylamino-7-chlorofluorane, 3-diethylamino-5-methyl-7-dibenzylaminofluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3-piperidino-6 −
Amino-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3-diethylamino-7-chloroanilinofluoran, 6′-dibutylamino-2 ′-(2-fluoro Anilino) spiro [phthalide-3,9'-xanthene]

The acidic phenol compound used in the heat-sensitive recording material of the present invention is not particularly limited as long as it is generally used in heat-sensitive recording materials. A specific example is as follows. 2,2-bis (p-hydroxyphenyl) propane, 1,1-bis (p-hydroxyphenyl) cyclohexane, 2,2-bis (p-
Hydroxyphenyl) hexane, 4-hydroxy-4 ′
-Isopropoxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfone, 2,4'-dihydroxydiphenylsulfone, 3,3'-diallyl-4,
4'-dihydroxydiphenylsulfone, 4,4'-
Dihydroxydiphenyl ether, 2,2-bis (4-
(Hydroxyphenyl) butyl acetate, 4,4′-thiobis (2-t-butyl-5-methylphenol), benzyl p-hydroxybenzoate, stearyl gallate, 3,5
-Di-t-butylsalicylic acid, zinc 3,5-di-t-butylsalicylate, zinc 4- [2 '-(4-methoxyphenoxy) ethyloxy] salicylate and the like.

As the binder used in the heat-sensitive recording layer, various binders used in ordinary coating can be used. For example, starches, hydroxymethylcellulose, carboxymethylcellulose, gelatin,
Casein, polyvinyl alcohol, modified polyvinyl alcohol, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid copolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride alkali Water-soluble binders such as salts, and emulsion-type aqueous binders such as styrene / butadiene copolymer, acrylonitrile / butadiene copolymer, methyl acrylate / butadiene copolymer, and the like.

In addition, diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, silicon oxide, aluminum hydroxide, urea-formalin resin and the like are used as pigments in the heat-sensitive recording layer. As a lubricant, zinc stearate, calcium stearate, paraffin, polyethylene oxide, stearic acid amide, caster wax, etc., and as a dispersing / wetting agent, a surfactant containing an anionic or nonionic high molecular weight, and further an ultraviolet ray. An absorbent, a fluorescent dye, an antifoaming agent and the like are added as needed.

The heat-sensitive recording material according to the present invention comprises a support and a heat-sensitive recording layer which is colored by heating. Paper is mainly used as the support, but in addition to paper, various woven fabrics, nonwoven fabrics, synthetic resin films, laminated paper, synthetic paper, metal foil, or composite sheets obtained by combining these are optionally used according to the purpose. be able to. The structure of the heat-sensitive recording layer may be a single layer or a multi-layer structure. For example, each coloring component is contained in each layer,
It may have a multilayer structure, such as providing a layer between the support and a protective layer on the heat-sensitive recording layer.

[0020]

Next, the present invention will be described in more detail with reference to examples.

[0021]

[0022]

[0023]

Examples 1 and 2 (A) Preparation of coating solution for thermal recording 150 g of 1,3-diimino-4,5,6,7-tetrachloroisoindoline was dispersed in 750 g of a 2% aqueous solution of polyvinyl alcohol. Pulverized with a bead mill and average particle size 1μ
m (dispersion liquid 1). Then, 100 g of 4,4 ', 4 "-triisocyanate-2,5-dimethoxytriphenylamine was added to 500 g of a 2% aqueous solution of polyvinyl alcohol.
, And pulverized with a bead mill to make the average particle size 1 μm (dispersion liquid 2). Furthermore, 150 g of benzyl (2-naphthyl) ether was added to a 75% aqueous solution of polyvinyl alcohol 75%.
0 g and dispersed in a bead mill to make the average particle size 1 μm (Dispersion 3). Aluminum pigment and zinc carbonate were each used as a pigment, and an oligomer product of sodium polyacrylate was used as a dispersant. 1.5% (solid content) was added to the pigment to obtain a 40% aqueous dispersion. Using these aqueous dispersions and a 10% polyvinyl alcohol solution, a thermosensitive recording coating solution having the composition shown in Table 1 below was prepared (numbers are parts by weight).

[0025]

[Table 1]

(B) Preparation of base paper for heat-sensitive recording material A coating liquid having the following composition is applied to a high-quality paper having a basis weight of 40 g / m ^{2 so} that the total coating amount is 25 g / m ² . After drying, a base paper for a heat-sensitive recording material was prepared. Calcined kaolin 100 parts by weight Sodium pyrophosphate 0.5 part by weight SBR latex (48%) 30 parts by weight Water 160 parts by weight

(C) Preparation of heat-sensitive recording material Each of the heat-sensitive recording coating solutions prepared in (A) was applied to the base paper prepared in (B) so that the total coating amount was 30 g / m ^2. And dried to obtain a heat-sensitive recording material.

The heat-sensitive recording materials prepared in Examples 1 and 2 and Comparative Example 1 were conditioned according to JIS-P8111, and each of the heat-sensitive recording materials was stored in a sealed state at 60 ° C. for 10 days in a drier. . These samples and the untreated sample were brought into contact with a heating block at 150 ° C. for 5 seconds to form a color, and the color density was measured. The results are shown in Table 2.

[0029]

[Table 2]

[0030]

As is clear from the examples, substituted or unsubstituted 1,3-diiminoisoindoline is used as the aromatic imino compound of the present invention, and the thermal reaction between the imino compound and the aromatic isocyanate compound is carried out. By adding zinc carbonate to the heat-sensitive coloring system utilizing the time reaction, it was possible to provide a heat-sensitive recording material in which the coloring performance of the heat-sensitive coloring system before use was greatly improved.

Continuation of the front page (56) References JP-A-4-74687 (JP, A) JP-A-2-107747 (JP, A) JP-A-3-150190 (JP, A) JP-A-59-135188 (JP) JP-A-59-135187 (JP, A) JP-A-5-238141 (JP, A) JP-A-6-8631 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) B41M 5/28-5/34

Claims (1)

(57) [Claims] 1. A thermosensitive recording material using a substituted or unsubstituted 1,3-diimino-isoindoline as an aromatic imino compound and utilizing a thermal reaction between the imino compound and an aromatic isocyanate compound. A heat-sensitive recording material comprising zinc in a heat-sensitive recording layer.