JPH11198541A - New thermosensitive coloring agent, and thermosensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the image preservation property and the coloring sensitivity by a method wherein a thermosensitive coloring agent contains an isocyanate compound, a colorless or slightly colored electron donating dye precursor and a hydroxyl group-cotaining compound. SOLUTION: This thermosensitive coloring agent contains an isocyanate compound, a colorless or a slightly colored electron donating dye precursor, hydroxyl group-containing compound which is represented by the formula. Then, the isocyanate compound is an isocyanate adduct body of which the melting point is 40 deg.C or higher. In the formula, Y1 indicates either one of -SO2 -, -(S)q -, -0-, -CO-, and -CH(COOY2 )-. (q is 1 or 2. Also, Y2 is an alkyl group.) (m), (n) each are integers of 0-3, and (m+n)>=1 is formed. Also, the hydrogen atom of the benzene ring may be replaced by a fatty compound residue which may have halogen atom or a substituent, or an inorganic compound residue.

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 which is used in various information devices such as facsimile machines, printers, recorders and the like and which can be used for heat-sensitive recording in which recording is performed using thermal energy. The present invention relates to a heat-sensitive color former and a heat-sensitive recording material using the same.

[0002]

2. Description of the Related Art In recent years, for example, in various information devices such as facsimile machines, printers, recorders, etc., a thermal recording system in which recording is performed by using thermal energy has been widely used. The mainstream of these recording methods is 2
Using a recording material having a coloring layer containing a thermosensitive coloring component on a support, and applying heat as recording energy to the coloring material, the thermosensitive coloring components are brought into contact with each other on the recording material to perform color recording. Is the way. Among them, many use a leuco dye and an acidic substance as a thermosensitive coloring agent.

[0003] Recording materials using these conventionally known leuco dyes have many excellent properties such as high whiteness, good appearance and feel close to plain paper, and good recording suitability such as color sensitivity. In addition, thermal recording has the advantages that the device is compact, maintenance-free, and does not generate noise.It has a wide range of applications such as measurement recorders, facsimile machines, printers, computer terminals, labels, and automatic ticket vending machines such as tickets. Applications have been expanded to the field. On the other hand, recording materials using these leuco dyes are, for example, typical examples of thermal paper (see US Pat. No. 3,539,375) using crystal violet lactone and 4,4′-isopropylidenediphenol (bisphenol A) as a thermosensitive coloring agent. As described above, because the chemical resistance of the recording part obtained by coloring is inferior, the recording may be easily lost by contact with a plasticizer contained in a plastic sheet or eraser or a chemical contained in food or cosmetics. Also, since the light resistance of the recording portion is inferior,
It has the drawback of poor storage stability of the record, such as fading or even disappearing of the record by exposure to sunlight for a relatively short period of time, and this drawback imposes certain restrictions on its use. At present, improvement is strongly desired.

As a heat-sensitive recording material capable of obtaining a recorded image having good storability in response to such demands, for example, Japanese Patent Application Laid-Open No.
8-38733, JP-A-58-54085, JP-A-58-104959, JP-A-58-149388,
JP-A-59-11587, JP-A-59-11588
No. 8 and U.S. Pat. No. 4,521,793 disclose a recording material comprising a combination of a thermosensitive coloring agent comprising an aromatic isocyanate and a thermosensitive coloring agent comprising an imino compound.

Japanese Patent Application Laid-Open No. 64-1580 discloses a thermosensitive color former comprising a dye precursor and an aromatic isocyanate compound. However, the color sensitivity and the image storability of recording are insufficient. However, there is a drawback that printing is erased by a plasticizer such as vinyl chloride wrap or the background is covered with heat. Japanese Patent Application Laid-Open No. 6-48041 discloses a thermosensitive coloring agent comprising a dye precursor, an isocyanate compound and an amino compound. However, there is a problem in that the image storability of the recording is incomplete and the background is covered by a plasticizer or heat.

JP-A-8-175021 describes that a dye precursor and an acid developer are added to a thermosensitive color former mainly composed of an isocyanate compound derived from toluene diisocyanate. However, a heat-sensitive color developing agent combining 4,4'-isopropylidenediphenol (bisphenol A), benzyl 4-hydroxybenzoate, or the like, which is an acidic developer often used as a heat-sensitive agent, is vinyl chloride. There is a drawback that the print disappears due to contact with the plasticizer or the like of the wrap, and improvement has been desired.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a thermosensitive color former comprising an isocyanate compound and a specific hydroxyl group-containing compound, and a thermosensitive recording material using the same which is excellent in image storability and color sensitivity. Aim.

[0008]

The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, surprisingly, the heat-sensitive agent containing a specific hydroxyl group-containing compound and an isocyanate compound has the above-mentioned disadvantages. It has been found that a heat-sensitive agent excellent in sensitivity, excellent in storage stability of printing, and free from background fogging can be obtained.

Furthermore, the inventors of the present invention have made extensive studies on the synthesis of isocyanate compounds using general-purpose isocyanate compounds as starting materials. As a result, the use of a specific isocyanate compound as the isocyanate compound has surprisingly improved. The present inventors have found that the present invention exhibits excellent performance, and have completed the present invention. That is, the present invention is as follows.

A first aspect of the present invention is a thermosensitive color former containing an isocyanate compound, a colorless or pale-color electron-donating dye precursor, and a hydroxyl-containing compound represented by the following formula (I).

[0011]

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(Where Y ₁ is —SO ₂ —, − (S) _q
—, —O—, —CO—, or —CH (COOY ₂ ) —. (Q is 1 or 2. Y ₂ is an alkyl group.) M and n are each an integer of 0 to 3 and (m + n) ≧ 1. Further, the hydrogen atom of the benzene ring may be substituted by a halogen atom or an aliphatic compound residue or an inorganic compound residue which may have a substituent. A second aspect of the present invention is the thermosensitive color former according to the first aspect, wherein the isocyanate compound is an isocyanate adduct compound having a melting point of 40 ° C. or more.

A third aspect of the present invention is the thermosensitive color former according to the first aspect, wherein the isocyanate compound is an isocyanate adduct compound represented by the following formula (II).

[0014]

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(Here, n represents an integer of 1 to 2. The hydrogen atom of the benzene ring may be substituted with an aromatic compound residue, an aliphatic compound residue, or a heterocyclic compound residue. Each residue may have a substituent.) A fourth aspect of the present invention is that the isocyanate compound has the following formula (II)
The thermosensitive color former according to the first aspect of the invention, which is an isocyanate adduct compound represented by I).

[0016]

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(Wherein m is an integer of 0 to 5, n is 1 or 2. Further, the hydrogen atom of the benzene ring is substituted by an aromatic compound residue, an aliphatic compound residue or a heterocyclic compound residue. Each residue may have a substituent, and X ₁ and X ₂ are each independently —SO ₂
-, - O -, - ( S) q -, - (CH 2) q -, - CO
-, - CONH -, - CH (C 6 H 5) -, - C (CH
_{3) 2} - shows the case where either or not present. q
Is 1 or 2. A fifth aspect of the present invention is that the isocyanate compound has the following formula (IV):
The heat-sensitive color former according to the first aspect of the present invention, which is an isocyanate compound represented by any one of (I) to (XII).

[0018]

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(Where m represents an integer of 1 to 4; Y ₃ represents a hydrogen atom or formula (a); R ₁ represents formula (b) or formula (c); the following formula (V) The same applies to (XII).

[0020]

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[0021]

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(Where n represents an integer of 1 to 2. The hydrogen atom of the benzene ring may be substituted by an aromatic compound residue, an aliphatic compound residue, or a heterocyclic compound residue. Each residue may have a substituent.)

[0023]

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(Wherein m is an integer of 0 to 5, n is 1 or 2. Further, the hydrogen atom of the benzene ring is substituted by an aromatic compound residue, an aliphatic compound residue, or a heterocyclic compound residue. Each residue may have a substituent, and X ₁ and X ₂ are each independently —SO ₂
-, - O -, - ( S) q -, - (CH 2) q -, - CO
-, - CONH -, - CH (C 6 H 5) -, - C (CH
_{3) 2} - shows the case where either or not present. q
Is 1 or 2. ))

[0025]

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(R ₂ represents an aromatic compound residue, a heterocyclic compound residue, or an aliphatic compound residue. Each residue may have a substituent. The following formula (VI) (V
Same in II) and (VIII). )

[0027]

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[0028]

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[0029]

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[0030]

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[0031]

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(R ₃ represents an aromatic compound residue, a heterocyclic compound residue or an aliphatic compound residue. Each residue may have a substituent.)

[0033]

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(R ₄ is an aromatic compound residue which may have a substituent or a heterocyclic compound residue which may have a substituent or an aliphatic compound residue or an inorganic compound residue which may have a substituent. Represents a group.)

[0035]

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(R ₅ and R ₆ each independently represent an aromatic compound, a heterocyclic compound or an aliphatic compound residue.
Each residue may have a substituent. R ₅ and R ₆ may form a cyclic structure with each other. In a sixth aspect of the invention, R ₁ is represented by the following formula (d) or the following formula (e):
The thermosensitive color former according to the fifth aspect of the invention, represented by the formula:

[0037]

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[0038]

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A seventh aspect of the present invention is the thermosensitive color former according to any one of the first to sixth aspects of the invention, which comprises an aromatic compound represented by the following formula (XIII).

[0040]

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(Where Y ₄ is —SO ₂ —, − (S) _q
-, - O -, - CH (C 6 H 5) -, - C (CH 3) 2
-, -CO-, -OCOO-, -COCO-, -NH
-, - shows the case where COCH ₂ CO- either or absent. (Q is 1 or 2.) Further, the hydrogen atom of the benzene ring may be substituted by a halogen atom, an aromatic compound residue, an aliphatic compound residue or a hetero compound residue. Eighth of the invention is the first to seventh inventions containing an organotin compound.
The thermosensitive coloring agent according to any one of the above.

A ninth aspect of the present invention is a thermosensitive recording material having a thermosensitive coloring layer containing the thermosensitive coloring agent according to any one of the first to eighth aspects on a support. Hereinafter, the present invention will be described in detail. The heat-sensitive agent of the present invention needs to contain an isocyanate compound. The isocyanate compound that can be used in the present invention can be appropriately selected from colorless or pale-colored isocyanate compounds that are solid at room temperature, and is not particularly limited. For example, one or more of the following isocyanate 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-methoxybenzene-2,4-diisocyanate, 1-methoxybenzene-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, diphenylether-4,4'-diisocyanate, naphthalene-1,4-diisocyanate, naphthalene-1,5-diisocyanate, naphthalene-
2,6-diisocyanate, naphthalene-2,7-diisocyanate, 3,3'-dimethyl-biphenyl-4,
4'-diisocyanate, 3,3'-dimethoxybiphenyl-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, bilen-3,8-di Isocyanate, naphthalene-1,3,7-triisocyanate, biphenyl-
2,4,4'-triisocyanate, 4,4 ', 4 "-
Triisocyanato-2,5-dimethoxytriphenylamine, 4,4 ', 4 "-triisocyanatotriphenylamine, 4,4'-diisocyanato-2,5dimethoxytriphenylamine, 4,4', 4" -Triisocyanato-2,5-diethoxytriphenylamine, p-dimethylaminophenyl isocyanate, tris (4-phenylisocyanato) thiophosphate and the like. These isocyanates may optionally contain phenols,
It may be used in the form of a so-called block isocyanate, which is an addition compound with lactams, oximes and the like.

In particular, it is preferable to use an isocyanate adduct compound having a melting point of 40 ° C. or more as the isocyanate compound from the viewpoint of color sensitivity and storage stability. The isocyanate adduct compound is a colorless or pale-colored solid at room temperature, and has a melting point of 40 ° C. or more, and preferably 40 ° C. or more and 500 ° C. or less. However, depending on the structure of the compound, it may be decomposed or deteriorated at a temperature lower than the melting point, and may not show the melting point.
If it is above, there is no problem in performance. The melting point is preferably at least 50 ° C, more preferably at least 60 ° C. When the melting point of the adduct compound is less than 40 ° C., when it is used as a thermosensitive coloring agent, problems are likely to occur in heat resistance and moisture resistance, which are often not preferable in practical use.

The isocyanate adduct compound is obtained by reacting at least one isocyanate group of the isocyanate with a reactive group and dimerizing the isocyanate with water through a urea bond or a biuret bond to form a dimer or trimer.
A method for quantification, a method for derivatization to a corresponding substituted urea or a substituted biuret by an addition reaction with an amine compound, a method for dimerization by heat, or a method for derivatization to a substituted urethane or a substituted allohanate by an addition reaction with an OH group-containing compound Or an addition reaction with a compound having an active hydrogen. Further, an isocyanate adduct compound obtained by carrying out any of the above-mentioned reactions using an isocyanate adduct compound obtained by the above method such as carbodiimide-modified MDI or polyol-modified MDI as a starting material may be used.

The starting material isocyanate is not particularly limited as long as it has two or more isocyanate groups. For example, paraphenylene diisocyanate, 2,5-
Dimethoxybenzene-1,4-diisocyanate, 2,
4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane diisocyanate, o
-Tolidine diisocyanate, 1,5-naphthylene diisocyanate, dianisidine diisocyanate, 9-ethylcarbazole-3,6-diisocyanate, 3,
3'-dimethyl-4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate 4,4 ', 4''-triisocyanatotriphenylamine, triphenylmethane triisocyanate, tris (4-phenyl isocyanate) thiophosphate and the like.

In particular, the isocyanate compound has the above formula (I)
It is preferable to be an isocyanate adduct represented by I) or the above formula (III) or an isocyanate compound represented by the above formulas (IV) to (XII). The adduct compound of an aromatic isocyanate represented by the above formula (II) refers to an isocyanate represented by the above formula (II), preferably at least one isocyanate of toluene diisocyanate starting from toluene diisocyanate. The addition reaction was performed using the group as a reactive group,
An isocyanate compound having at least one isocyanate group.

The toluene diisocyanate is 2,4
-Toluene diisocyanate and 2,6-toluene diisocyanate are generally commercially available, and can usually be obtained at low cost as a mixture thereof. However, these toluene diisocyanate isomer mixtures are liquid at room temperature (100% 2,4-toluene diisocyanate, melting point 19.5 ° C.-21.5 ° C., 2,4-toluene diisocyanate 65%). / 35% mixture of 2,6-toluene diisocyanate at 35 ° C. to 5.5 ° C.
° C), and it is practically difficult to use this form as a thermosensitive coloring agent.

The isocyanate adduct compound represented by the above formula (III) is an aromatic isocyanate represented by the above formula (III) or polymethylene polyphenyl polyisocyanate (hereinafter referred to as cr.MDI) or Diphenylmethane diisocyanate (hereinafter MD)
It means a new isocyanate compound obtained by performing the addition reaction in I).

The above cr. MDI or MDI is generally commercially available and can usually be obtained at low cost. However, for example, cr. MDI is a room temperature brown liquid, MDI has a freezing point of 38 ° C.,
There is a practical problem in using it as a thermosensitive color former. The isocyanate adduct compound may be an isocyanate compound represented by the above formula (II), in particular, toluene diisocyanate, an aromatic isocyanate represented by the above formula (III) or cr. It is an isocyanate compound containing at least one isocyanate group obtained by performing an addition reaction using at least one isocyanate group of isocyanate such as MDI or MDI as a reactive group. That is, the isocyanate adduct compound that can be used in the present invention is an isocyanate compound represented by the above formula (II),
Particularly, toluene diisocyanate, aromatic isocyanate represented by the above formula (III) or cr. MDI, MD
A method in which at least one isocyanate group of an isocyanate such as I is used as a reactive group, the isocyanate is dimerized or trimerized through a urea bond or a biuret bond by a reaction with water, or by an addition reaction with an amine compound. A method of deriving to the corresponding substituted urea or substituted biuret, or a method of dimerization by heat, a method of deriving to a substituted urethane or a substituted allohanate by an addition reaction with an OH group-containing compound, or a compound having an active hydrogen Can be obtained by an addition reaction method or the like. Further, an isocyanate adduct compound obtained by performing any one of the above-mentioned reactions using the isocyanate adduct compound obtained by the above method as a starting material may be used.
In other words, by using this technology, by increasing the melting point to 40 ° C. or higher by increasing the molecular weight, heat resistance, moisture resistance, etc. are improved, so that there is no practical problem as a heat-sensitive color former and excellent performance can be exhibited. Become.

The above formula (I) which can be used in the present invention
The aromatic isocyanate compound represented by I) may be any compound having two or more NCO groups on the benzene ring. Examples thereof include p-phenylene diisocyanate, m-phenylene diisocyanate, and toluene diisocyanate. 1,3-dimethylbenzene-4,6-diisocyanate, 1,4-dimethylbenzene-2,5-diisocyanate, 1-methoxybenzene-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- And diisocyanates. Particularly preferred is toluene diisocyanate, wherein toluene diisocyanate is
Any of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate or a mixture thereof may be used.

The aromatic isocyanate represented by the above formula (III) which can be used in the present invention includes, for example, dianisidine diisocyanate, diphenyl ether diisocyanate, orthotrizine diisocyanate, bis [4- (m -Isocyanatophenoxy) phenyl] sulfone, bis [4- (p-isocyanatophenoxy) phenyl] sulfone, bis [3-methyl-4- (p-isocyanatophenoxy) phenyl] sulfone, 3,3′-
Dimethoxy-4,4'-diisocyanatobiphenyl,
3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 2,2'-dichloro-4,4'-diisocyanato-5,5'-dimethoxybiphenyl, 2,2 ', 5
5'-tetrachloro-4,4'-diisocyanatobiphenyl, 2,4'-diisocyanatobiphenyl, 2,2 '
-Diisocyanatobiphenyl, 4,4'-diisocyanatobiphenyl, 2,2'-dichloro-4,4'-diisocyanatobiphenyl, 3,3'-dichloro-4,4'-
Diisocyanatobiphenyl, 2,2'-dimethyl-4,
4'-diisocyanatobiphenyl, 4,4'-diisocyanatodiphenylether, 3,3'-diisocyanatodiphenylether, 3,4'-diisocyanatodiphenylether, 3,4'-diisocyanatodiphenylmethane, bis ( 3-isocyanato-4-chlorophenyl)
Sulfone, bis (3,4-diisocyanatophenyl) sulfone, bis (4-isocyanatophenyl) sulfone,
Bis (3-isocyanatophenyl) sulfone, 3,4 '
Diisocyanatodiphenylsulfone, 3,3'-diisocyanatodiphenylmethane, 4,4'-diisocyanato-3,3'-dichlorodiphenylmethane, 1,4-bis (4-isocyanatophenoxy) benzene, 1,3-
Bis (4-isocyanatophenoxy) benzene, 1,3
-Bis (3-isocyanatophenoxy) benzene, 2,
2-bis (4-isocyanatophenoxyphenyl) propane, 4,4'-bis (4-isocyanatophenoxy)
Examples thereof include diphenyl, 3,3 ', 4,4'-tetraisocyanatodiphenyl ether, 3,3', 4,4'-tetraisocyanatodiphenylsulfone and the like. These aromatic isocyanate or polymethylene polyphenyl polyisocyanate (cr.MDI) or diphenylmethane diisocyanate (MDI) may be used alone or in a mixture thereof.

As the reactant for forming these isocyanate adducts, in addition to water, for example, aniline, o-toluidine, m-toluidine, p-toluidine, o-anisidine, p-anisidine, p-phenetidine, N, N-
Dimethylaniline, N, N-diethylaniline, N, N
-Dimethyl-p-phenylenediamine, N, N-diethyl-p-phenylenediamine, 2,4-dimethoxyaniline, 2,5-dimethoxyaniline, 3,4-dimethoxyaniline, p-aminoacetanilide, p-aminobenzoic acid , O-aminophenol, m-aminophenol, p-aminophenol, 2,3-xylysine, 2,
4-xylidine, 3,4-xylidine, 2,6-xylidine, acetanilide, 4-aminobenzonitrile, anthranilic acid, p-cresidine, 2,5-dichloroaniline, 2,6-dichloroaniline, 3,4-dichloro Aniline, 3,5-dichloroaniline, 2,4,5-trichloroaniline, α-naphthylamine, aminoanthracene, o-ethylaniline, o-chloroaniline, m-
Chloroaniline, p-chloroaniline, N-methylaniline, N-ethylaniline, N-propylaniline, N
-Butylaniline, N, N-diglycidylaniline,
N, N-diglycidyl-o-toluidine, acetoacetic anilide, trimethylphenylammonium bromide,
4'-diamino-3,3'-diethyldiphenylmethane, 4,4'-diaminobenzanilide, 3,5-diaminochlorobenzene, diaminodiphenyl ether,
3,3'-dichloro-4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, trizine base, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2- Chloro-p-phenylenediamine, dianisidine, methyl p-aminobenzoate, ethyl p-aminobenzoate, n-propyl p-aminobenzoate, iso-propyl p-aminobenzoate, butyl p-aminobenzoate, dodecyl p-aminobenzoate, benzyl p-aminobenzoate, o-aminobenzophenone, m-aminoacetophenone, p-aminoacetophenone, m-aminobenzamide, o-aminobenzamide, p-aminobenzamide, p-amino-N- Methylbenzamide, 3-
Amino-4-methylbenzamide, 3-amino-4-methoxybenzamide, 3-amino-4-chlorobenzamide, p- (N-phenylcarbamoyl) aniline, p
-[N- (4-chlorophenyl) carbamoyl] aniline, p- [N- (4-aminophenyl) carbamoyl]
Aniline, 2-methoxy-5- (N-phenylcarbamoyl) aniline, 2-methoxy-5- [N- (2'-methyl-3'-chlorophenyl) carbamoyl] aniline, 2-methoxy-5- [N- ( 2'-chlorophenyl) carbamoyl] aniline, 5-acetylamino-2
-Methoxyaniline, 4-acetylaminoaniline, 4
-(N-methyl-N-acetylamino) aniline, 2,
5-diethoxy-4- (N-benzoylamino) aniline, 2,5-dimethoxy-4- (N-benzoylamino) aniline, 2-methoxy-4- (N-benzoylamino) -5-methylaniline, 4- Sulfamoylaniline, 3-sulfamoylaniline, 2- (N-ethyl-N-phenylaminosulfonyl) aniline, 4-dimethylaminosulfonylaniline, 4-diethylaminosulfonylaniline, sulfathiazole, 4-aminodiphenylsulfone, 2-chloro-5-N-phenylsulfamoylaniline, 2-methoxy-5-N, N-diethylsulfamoylaniline, 2,5-dimethoxy-4
-N-phenylsulfamoylaniline, 2-methoxy-5-benzylsulfonylaniline, 2-phenoxysulfonylaniline, 2- (2'-chlorophenoxy) sulfonylaniline, 3-anilinosulfonyl-4-methylaniline, bis [ 4- (m-aminophenoxy) phenyl] sulfone, bis [4- (p-aminophenoxy)
Phenyl] sulfone, bis [3-methyl-4- (p-aminophenoxy) phenyl] sulfone, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diamino Biphenyl, 2,2'-dichloro-4,4'-diamino-5,5'-dimethoxybiphenyl, 2,2 ', 5,5'-tetrachloro-4,
4'-diaminobiphenyl, ortho-tolidine sulfone, 2,4'-diaminobiphenyl, 2,2'-diaminobiphenyl, 4,4'-diaminobiphenyl, 2,
2'-dichloro-4,4'-diaminobiphenyl, 3,
3'-dichloro-4,4'-diaminobiphenyl, 2,
2'-dimethyl-4,4'-diaminobiphenyl, 4,
4'-thiodianiline, 2,2'dithiodianiline,
4,4'-dithiodianiline, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4 '
-Diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, bis (3-amino-4-chlorophenyl) sulfone, bis (3,4-diaminophenyl) sulfone, bis (4-aminophenyl) sulfone, bis (3
-Aminophenyl) sulfone, 3,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylmethane, 4,4-diaminodiphenylamine, 4,4'-ethylenedianiline, 4,4'diamino-2,2'- Dimethyldibenzyl, 3,3'-diaminobenzophenone,
4,4'-diaminobenzophenone, 1,4-bis (4
-Aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 9,9-bis (4-aminophenyl) fluorene, 2,2-bis (4-aminophenoxyphenyl) propane, 4,4'-bis (4-aminophenoxy) diphenyl, 3,3 ', 4,4'-tetraaminodiphenyl ether, 3,3', 4,4'-tetraaminodiphenyl Sulfone, 3,3'4,4'-tetraaminobenzophenone, 3-aminobenzonitrile,
-Phenoxyaniline, 3-phenoxyaniline, 4,
4'-methylenebis-O-toluidine, 4,4 '-(p
-Phenyleneisopropylidene) -bis- (2,6-xylidine), o-chloro-p-nitroaniline, o-nitro-p-chloroaniline, 2,6-dichloro-4-nitroaniline, 5-chloro-2 -Nitroaniline, 2-
Amino-4-chlorophenol, o-nitroaniline,
m-nitroaniline, p-nitroaniline, 2-methyl-4-nitroaniline, m-nitro-p-toluidine,
2-amino-5-nitrobenzonitrile, methol,
2,4-diaminophenol, p-hydroxyphenylglycine, N- (β-hydroxyethyl) -o-aminophenol sulfate, sulfanilic acid, metanylic acid, 4B
Acid, C acid, 2B acid, p-fluoroaniline, o-fluoroaniline, 3-chloro-4-fluoroaniline, 2,
4-difluoroaniline, 2,3,4-trifluoroaniline, m-aminobenzotrifluoride, m-toluylenediamine, 2-aminothiophenol, 2-amino-3-bromo-5-nitrobenzonitrile, diphenylamine, p-aminodiphenylamine, octylated diphenylamine, 2-methyl-4-methoxydiphenylamine, N, N-diphenyl-p-phenylenediamine, dianisidine, 3,3′-dichlorobenzidine,
4,4′-diaminostilbene-2,2′-disulfonic acid, benzylethylaniline, 1,8-naphthalenediamine, sodium naphthionate, tobias acid, H acid, J acid,
Phenyl J acid, 1,4-diamino-anthraquinone,
Aromatic amines such as 1,4-diamino-2,3-dichloroanthraquinone, 3-amino-1,2,4-triazole, 2-aminopyridine, 3-aminopyridine, 4-aminopyridine, α-amino -Ε-caprolactam, acetoguanamine, 2,4-diamino-6
[2′-methylimidazolyl- (1)] ethyl-S-triazine, 2,3-diaminopyridine, 2,5-diaminopyridine, 2,3,5-triaminopyridine, 1-amino-4-methylpiperazine, 1- (2-aminoethyl) piperazine, bis (aminopropyl) piperazine,
Heterocyclic compounds such as N- (3-aminopropyl) morpholine amines, methylamine, ethylamine, dimethylamine, diethylamine, stearylamine, allylamine, diallylamine, isopropylamine, diisopropylamine, 2-ethylhexylamine, ethanolamine, (2-ethylhexyloxy) propylamine, 3-ethoxypropylamine, diisobutylamine, 3- (diethylamino) propylamine, di-2-
Ethylhexylamine, 3- (dibutylamino) propylamine, t-butylamine, propylamine, 3-
(Methylamino) propylamine, 3- (dimethylamino) propylamine, 3-methoxypropylamine, methylhydrazine, 1-methylbutylamine, methanediamine, 1,4-diaminobutane, cyclohexanemethylamine, cyclohexylamine, 4-methyl Cyclohexylamine, 2-bromoethylamine, 2-methoxyethylamine, 2-ethoxymethylamine, 2-amino-
1-propanol, 2-aminobutanol, 3-amino-1,2-propanediol, 1,3-diamino-2-
Aliphatic amines such as hydroxypropane and 2-aminoethanethiol, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, tetrakis (2 , 2,6,6
-Tetramethyl-4-piperidyl) -1,2,3,4-
Butanetetracarboxylate, 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol, β, β, β ′, β′-tetramethyl-3,9 -(2,4,8,10-tetraoxaspiro [5,5] undecanediethanol condensate, 1,
2,3,4-butanetetracarboxylic acid ・ 2,2,6,6
-Tetramethyl-4-piperidinol, β, β, β ',
β'-tetramethyl-3,9- (2,4,8,10-tetraoxaspiro [5,5] undecanediethanol condensate, poly [{6- (1,1,3,3-tetramethylbutyl)] Amino-1,3,5-triazine-2,4-diyl {(2,2,6,6-tetramethyl-4-piperidyl) imino} hexamethylene} (2,2,6,6-tetramethyl- 4-piperidyl) imino}], N, N'-bis (3-aminopropyl) ethylenediamine-2,4-
Bis [N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,
3,5-triazine condensate, 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonic acid-bis (1,2,2,6,6-pentamethyl-4 −
Hindered amine compounds such as piperidyl) and succinic acid-bis (2,2,6,6-tetramethyl-4-piperidienyl) ester.

Further, examples of the OH group-containing compound as a reactant for forming an adduct include phenol, cresol, xylenol, p-ethylphenol, o-isopropylphenol, resorcinol, p-tert-butylphenol, p-tert-butylphenol. Octylphenol, 2-
Cyclohexylphenol, 2-allylphenol, 4
-Indanol, thymol, 2-naphthol, p-nitrophenol, o-chlorophenol, p-chlorophenol, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (hydroxyphenyl) butane,
2,2-bis (hydroxyphenyl) pentane, 2,2
-Bis (hydroxyphenyl) heptane, catechol,
3-methylcatechol, 3-methoxycatechol, pyrogallol, hydroquinone, methylhydroquinone,
-Phenylphenol, p, p'-biphenol, 4-
Phenols such as cumylphenol (however, those phenols having an amino group are not preferred. When an amino group is present, the amino group reacts first because the reactivity with an isocyanate group is higher than that of an OH group. The desired compound cannot be obtained.) Methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, isopropanol, 2-pentanol, 3-hexanol, ter
t-butanol, tert-amyl alcohol, methyl cellosolve, butyl cellosolve, methyl carbitol,
Allyl alcohol, 2-methyl-2-propen-1-ol, benzyl alcohol, 4-pyridinemethanol,
Phenyl cellosolve, furfuryl alcohol, cyclohexanol, cyclohexylmethanol, cyclopentanol, 2-chloroethanol, 1-chloro-3-hydroxypropane, alcohols such as glycerin, glycerol, polypropylene glycol, polytetramethylene ether glycol, adipate Polyether polyols such as polyols, epoxy-modified polyols, polyether ester polyols, polycarbonate polyols, polycaprolactone diols, phenolic polyols, amine-modified polyols, ethylene glycol, diethylene glycol, 1,3-propanediol, 1,2-propanediol , Propylene glycol, dipropylene glycol, 1,4-butanediol, 1,5-pentanedio 1,6-hexanediol, 1,6-hexaneglycol, 1,9-nonanediol, acrylic polyol, fluorine polyol, polybutadiene polyol, polyhydroxypolyol, trimethylolpropane, trimethylolethane, hexanetriol, phosphoric acid, Neopentyl glycol, pentaerythritol, castor oil-based polyols, polymer polyols, methylpentanediol, halogen-containing polyols, phosphorus-containing polyols, polyols such as ethylenediamine, α-methylglucoside, sorbitol, and soucrose, and other activities to react with isocyanates As compounds having hydrogen, dimethyl malonate, diethyl malonate, ethyl acetoacetate, butyl mercaptan, thiophenol, tert-dodecyl mercaptan, Cetanisidide, acetate amide, benzamide, p-toluenesulfonamide, o-toluenesulfonamide, p-chlorobenzenesulfonamide, benzenesulfonamide, hydrazine, hydroxylamine, succinimide, maleic imide, acetanilide, imidazole, methylethylketoxime, acetoacetate Examples include aldoximes, sodium bisulfite, urea, ammonia, imino compounds such as 3-iminoisoindoline and iminobenzophenone, and imine compounds such as piperidine, ethyleneimine and piperazine.

In the production of the isocyanate adduct compound that can be used in the present invention, the reaction can be performed without a solvent, but it is preferable to use a solvent. The solvent used is one that dissolves the isocyanate and dissolves the reactants to some extent. After mixing and reacting the reactant with the isocyanate in an organic solvent or in the absence of a solvent, the surplus isocyanate is removed by filtration or distillation under reduced pressure to obtain the desired product. A single or a plurality of reactants may be used depending on the purpose. The solvent may be any one that does not cause a reaction with the isocyanate group and the functional group of the reactant.
Organic solvents such as aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, chlorinated aliphatic hydrocarbons, chlorinated aromatic hydrocarbons, and chlorinated alicyclic hydrocarbons are exemplified. Especially,
Cyclohexane, ethylcyclohexane, toluene and the like which dissolve the isocyanate and have low solubility of the product are preferable. The product obtained by the above reaction operation is not necessarily a single product, but a mixture of a compound having different substituent positions, a mixture of a substituted urea and a substituted biuret, a mixture of a substituted urethane and a substituted allohanate, and further an addition reaction proceeds. It may be obtained as a mixture of those having a molecular weight, but this is also acceptable. The target product can also be obtained by reacting the reaction agent with the product obtained by the above reaction operation as a starting material.

The amount of the reactant used for the isocyanate varies greatly depending on the solubility of the reactant in the reaction solvent. Reactants that can dissolve the required amount in the reaction solvent
The amount of the reactant corresponding to the NCO group of the isocyanate may be used. When the agent reacts with the isocyanate and is lost from the solvent, a new reactant may be dissolved in the solvent and contribute to the reaction. Therefore, the reactants in the solvent can be mixed in excess of the isocyanate.

The melting point of the isocyanate adduct compound thus obtained may be 40 ° C. or higher, preferably 50 ° C. or higher, more preferably 60 ° C. or higher. When the melting point of the adduct compound is less than 40 ° C., when it is used as a thermosensitive coloring agent, problems are likely to occur in heat resistance, moisture resistance and the like, which is not preferable in practical use. The upper limit of the melting point is 5
00 ° C or lower is preferred. However, depending on the structure of the compound, the compound may decompose or degrade at a temperature lower than the melting point to show no melting point, but in this case, there is no problem in performance as long as the lower limit of the melting point is satisfied.

These isocyanate compounds may be converted into adducts with phenols, lactams, oximes and the like, if necessary, to mask the isocyanate, and dissociate upon application of heat to regenerate the isocyanate. It may be used in the form of isocyanate. The isocyanate compound, the isocyanate adduct compound or the isocyanate compound represented by the formulas (IV) to (XII) used in the present invention is a colorless or pale color solid at room temperature. In preparing the heat-sensitive recording material, one or a mixture of the isocyanate compound, the isocyanate adduct compound or the isocyanate compound represented by the formulas (IV) to (XII) is used. You can also.

The isocyanate compounds represented by the formulas (IV) to (XII) can be obtained by subjecting the corresponding amine compound to a phosgene reaction to form an isocyanate. It is possible. When used as an isocyanate adduct compound, it is preferable that 30% or more of the isocyanate is an adduct, and it is preferable that 50% or more of the isocyanate is an adduct. Further, it is preferable that 80% or more is an adduct body.

The heat-sensitive color former of the present invention needs to contain a colorless or light-colored electron-donating dye precursor. The colorless or light-colored electron-donating dye precursor used in the present invention is a compound already known as a heat-sensitive color former used in a heat-sensitive recording material, and is not particularly limited, and examples thereof include the following. .

(1) Triarylmethane compound 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (crystal violet lactone), 3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3-
(1,2-dimethylindol-3-yl) phthalide,
3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindole-
3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindole-3-
Yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3-bis (2-phenylindol-3-yl) -5 -Dimethylaminophthalide, 3-
p-dimethylaminophenyl-3- (1-methylpyrrol-2-yl) -6-dimethylaminophthalide and the like.

(2) Diphenylmethane compounds 4,4-bis-dimethylaminophenylbenzhydrylbenzyl ether, N-halophenylleucouramine, N-2,4,5-trichlorophenylleucouramine and the like. (3) Fluoran compounds Rhodamine B anilinolactam, rhodamine Bp-chloroanilinolactam, 3-diethylamino-7-dibenzylaminofluoran, 3-diethylamino-7-octylaminofluoran, 3-diethylamino-7 -Phenylfluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino-6-chloro-7-methylfluoran, 3-diethylamino-7- (3,4-dichloroanilino) fluoran, 3-diethylamino- 7
-(2-chloroanilino) fluoran, 3-diethylamino-6-methyl-7-anilinofluoran, 3- (N
-Ethyl-N-tolyl) amino-6-methyl-7-anilinofluoran, 3-piperidino-6-methyl-7-anilinofluoran, 3- (N-ethyl-N-tolyl) amino-6 Methyl-7-phenethylfluoran, 3-diethylamino-7- (4-nitroanilino) fluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-propyl) amino-
6-methyl-7-anilinofluoran, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluoran, 3- (N-methyl-N-cyclohexyl) amino-6 Methyl-7-anilinofluoran, 3
-(N-ethyl-N-tetrahydrofuryl) amino-6
-Methyl-7-anilinofluoran and the like.

(4) Thiazine compounds benzoyl leucomethylene blue, p-nitrobenzoyl leucomethylene blue and the like. (5) Spiro compound 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3-dichlorospirodinaphthopyran, 3-benzylspirodinaphthopyran, 3-methylnaphtho- (3-methoxybenzo) Spiropyran, 3-propyl spirobenzopyran, and the like. Also, 3,6-bis (dimethylamino) fluorene-9-spiro-3 ^, -
(6 ^, -dimethylaminophthalide), 3,3-bis [2
-(4-dimethylaminophenyl) -2- (4-methoxyphenyl) ethenyl] -4,5,6,7, -tetrachlorophthalide and other compounds having an absorption region in the near infrared.

The colorless or pale color dye precursor is preferably used in an amount of 5 to 500% by weight of the isocyanate compound, more preferably 20 to 200% by weight. In the thermosensitive coloring agent of the present invention, it is necessary to use the hydroxyl group-containing compound represented by the above formula (I). When this compound is used in combination with an isocyanate compound, an isocyanate adduct or an isocyanate compound represented by any one of formulas (IV) to (XII), the effect of surprisingly improving the image preservability is obtained.

The hydroxyl group-containing compound represented by the above formula (I) can be appropriately selected from colorless or light-colored hydroxyl group-containing compounds which are solid at ordinary temperature. Representative examples of the hydroxyl group-containing compound represented by the above formula (I) that can be used in the present invention include, for example, bis (4-hydroxyphenyl)
Butyl acetate, bis (4-hydroxyphenyl) benzyl acetate, bis (4-hydroxyphenyl) sulfone, bis (3-methyl-4-hydroxyphenyl) sulfone, bis (3,5-dimethyl-4-hydroxyphenyl) sulfone, 4-hydroxyphenyl-4'-methylphenylsulfone, 3-chloro-4-hydroxyphenyl-4 '
-Methylphenylsulfone, 3,4-dihydroxyphenyl-4'-methylphenylsulfone, 4-isopropylphenyl-4'-hydroxyphenylsulfone, 4-
Isopropyloxyphenyl-4′-hydroxyphenylsulfone, bis (2-allyl-4-hydroxyphenyl) sulfone, 4-hydroxyphenyl-4′-benzyloxyphenylsulfone, 4-isopropylphenyl-4′-hydroxyphenylsulfone, -Hydroxy-4'-isopropoxydiphenyl sulfone, bis (2
-Methyl-3-tert. -Butyl-4-hydroxyphenyl) sulfide, 4,4'-dihydroxydiphenyl ether, 4,4'-thiodiphenol, 4,4'-
And dihydroxybenzophenone.

The hydroxyl group-containing compound represented by the above formula (I) is preferably used in an amount of 5 to 1000% by weight, more preferably 50 to 500% by weight of the isocyanate compound. If the content of the hydroxyl group-containing compound is less than 5% by weight based on the isocyanate compound, a sufficient effect cannot be obtained. Further, even if it is used in excess of 1000% by weight, no improvement in performance is observed, and it is disadvantageous in terms of cost.

The isocyanate compound, isocyanate adduct compound or a compound of the formula (IV) to (XII) of the present invention
An isocyanate compound represented by at least one of the above, a colorless or pale-colored dye precursor, and the above formula (I)
By adding the aromatic compound represented by the above formula (XIII) to the thermosensitive color former comprising a hydroxyl group-containing compound represented by the formula (1), the sensitivity is improved, and a heat-sensitive recording material having more vivid color development can be obtained.

The aromatic compound represented by the formula (XIII) used in the present invention can be appropriately selected from colorless or pale-colored aromatic compounds which are solid at ordinary temperature. Examples of typical aromatic compounds represented by the above formula (XIII) that can be used in the present invention include, for example, 4,4′-dimethoxybenzophenone, 4,4′-dichlorobenzophenone, 4,4′-difluorobenzophenone, Diphenyl sulfone, 4,4′-dichlorodiphenyl sulfone,
4,4'-difluorodiphenyl sulfone, 4,4'-
Dichlorodiphenyl disulfide, diphenylamine, 2-methyl-4-methoxydiphenylamine, N,
N'-diphenyl-p-phenylenediamine, 1- (N
-Phenylamino) naphthalene, benzyl, 1,3-diphenyl-1,3-propanedione and the like.

The aromatic compound represented by the above formula (XIII) is preferably used in an amount of 5 to 1000% by weight, more preferably 50 to 500% by weight of the isocyanate compound. The heat-sensitive agent of the present invention can contain an organotin compound. By adding this, the coverage of the background is further reduced.

The organotin compound has tetravalent tin in the molecule,
It is a compound having at least one alkyl group. The compound is a colorless or light-colored compound that is solid or liquid at room temperature and is odorless or low-odor. For example, di-n-octyltinbis (isooctylthioglycolic acid alkyl ester), di-n- Octyltin maleic acid polymer, di-n-octyltin dimethyl maleate, di-n-octyltin dilaurate, di-n-octyltin distearate, poly (thiobis-
n-butyltin sulfide), monooctyltin tris (isooctylthiofuric acid alkyl ester),
Di-n-octyltin oxide, di-n-octyltin dichloride, tetra-n-octyltin, di-n-octyltin diversate, di-n-octyltin alkyl mercaptide, di-n-methyltin alkyl mercaptide And so on. The organotin compound may be used alone or as a mixture, and is preferably 1 to 500% by weight based on the leuco dye. When an isocyanate compound is added to the thermosensitive color former, the content is preferably 1 to 500% by weight based on the isocyanate compound. The content of the organotin compound is 1% by weight based on the isocyanate compound.
If less than the above, a sufficient effect cannot be obtained. 500% by weight
Not only does performance increase appear when used beyond
It is disadvantageous in terms of cost.

Further, in order to improve background fogging and thermal response, N-stearyl-N '-(2-hydroxyphenyl) urea, N-stearyl-N'-(3-hydroxyphenyl) urea, N-stearyl-N '-(3-hydroxyphenyl) urea Stearyl-N ′-(4-hydroxyphenyl) urea, p-stearoylaminophenol, o-stearoylaminophenol, p-lauroylaminophenol, p-butyrylaminophenol, m-acetylaminophenol, o-acetylaminophenol, p-acetylaminophenol, o-butylaminocarbonylphenol, o-stearylaminocarbonylphenol, p-stearylaminocarbonylphenol, 1,1,3-tris (3-tert.
-Butyl-4-hydroxy-6-methylphenyl) butane, 1,1,3-tris (3-tert.-butyl-4)
-Hydroxy-6-ethylphenyl) butane, 1,1,
3-tris (3,5-di-tert.-butyl-4-hydroxyphenyl) butane, 1,1,3-tris (3-
tert. -Butyl-4-hydroxy-6-methylphenyl) propane, 1,2,3-tris (3-tert.
-Butyl-4-hydroxy-6-methylphenyl) butane, 1,1,3-tris (3-phenyl-4-hydroxyphenyl) butane, 1,1,3-tris (3-cyclohexyl-4-hydroxy-5) -Methylphenyl) butane, 1,1,3-tris (3-cyclohexyl-4-hydroxy-6-methylphenyl) butane, 1,1,3-
Tetra (3-phenyl-4-hydroxyphenyl) propane, 1,1,3,3-tetra (3-cyclohexyl-
4-hydroxy-6-methylphenyl) propane, 1,
1-bis (3-tert.-butyl-4-hydroxy-
It is also possible to add phenol compounds such as 6-methylphenyl) butane and 1,1-bis (3-cyclohexyl-4-hydroxy-6-methylphenyl) butane.

The heat-sensitive recording sheet according to the present invention can contain a heat-fusible substance in order to improve the sensitivity. The heat-fusible substance preferably has a melting point of 60C to 180C, and particularly preferably has a melting point of 80C to 140C. For example, benzyl p-benzyloxybenzoate, stearamide, palmitamide,
N-methylol stearamide, β-naphthyl benzyl ether, N-stearyl urea, N, N′-distearyl urea, β-naphthoic acid phenyl ester,
-Hydroxy-2-naphthoic acid phenyl ester, β-
Naphthol (p-methylbenzyl) ether, 1,4-
Dimethoxynaphthalene, 1-methoxy-4-benzyloxynaphthalene, N-stearoylurea, 4-benzylbiphenyl, 1,2-di (m-methylphenoxy) ethane, 1-phenoxy-2- (4-chlorophenoxy)
Examples thereof include ethane, 1,4-butanediol phenyl ether, dimethyl terephthalate, metaterphenyl, dibenzyl oxalate, and oxalic acid (P-chlorobenzyl) ester.

The above-mentioned heat-fusible substance may be used alone or as a mixture. In order to obtain a sufficient thermal response, 10 to 300% by weight based on the isocyanate compound is used.
It is preferably used, and more preferably 20 to 250% by weight. In order to obtain a heat-sensitive recording material, these isocyanate compounds, dye precursors, hydroxyl-containing compounds represented by the above formula (I), and compounds represented by the above formula (XII)
It is necessary to apply the aromatic compound or organotin compound represented by I) in the form of a dispersion to a support together with other necessary components to form a heat-sensitive recording layer. The dispersion can be prepared by pulverizing one or more of these compounds in an aqueous solution containing a compound having a dispersing ability such as a water-soluble polymer or a surfactant. The particle diameter of each dispersion is preferably about 1 μm. The isocyanate compound may be dispersed at the same time as the hydroxyl group-containing compound.

In addition, the thermal recording layer contains diatomaceous earth, talc, kaolin, calcined kaolin, calcium carbonate, magnesium carbonate, titanium oxide, zinc oxide, silicon oxide, aluminum hydroxide, urea-formalin resin and the like as pigments. You can also. In addition, for the purpose of preventing head wear and sticking, zinc stearate, higher fatty acid metal salts such as calcium stearate, paraffin,
Waxes such as paraffin oxide, polyethylene, polyethylene oxide, stearamide, castor wax, dispersants such as sodium dioctyl sulfosuccinate, ultraviolet absorbers such as benzophenone and benzotriazole, surfactants, and fluorescent dyes Etc. can be contained as needed.

As the binder used for the heat-sensitive recording layer, various binders which are usually used can be used. Examples of such binders include starches, hydroxyethyl cellulose, methyl cellulose,
Carboxymethylcellulose, gelatin, casein, polyvinyl alcohol, modified polyvinyl alcohol, sodium polyacrylate, acrylamide / acrylate copolymer, acrylamide / acrylate / methacrylic acid terpolymer, styrene / maleic anhydride copolymer Water-soluble binders such as alkali salts of ethylene, alkali salts of ethylene / maleic anhydride copolymers, and water-insoluble latexes such as styrene / butadiene copolymers, acrylonitrile / butadiene copolymers, and methyl acrylate / butadiene copolymers Binders and the like.

The heat-sensitive recording material according to the present invention comprises a support having thereon a heat-sensitive recording layer which develops color by heating. As the support, paper is mainly used, 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 thermal recording layer may be composed of a single layer or a plurality of layers. For example, each color forming component may be contained one layer at a time to form a multilayer structure. Further, a protective layer consisting of one or more layers may be provided on the heat-sensitive recording layer, or an intermediate layer consisting of one or more layers may be provided between the support and the heat-sensitive recording layer. Good. This heat-sensitive recording layer can be obtained by mixing each aqueous dispersion obtained by finely pulverizing each color-forming component or other components, a binder and the like, applying the mixture on a support, and drying.

[0077]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the following examples. In addition, each physical property was evaluated by the following methods. <Sensitivity> A printing tester manufactured by Okura Electric Co., Ltd., and the thermal head applied voltage was 2 using Kyocera KJT-256-8MGF1.
The color density at a 4 V pulse width of 1.5 msec was measured with an optical densitometer. <Plasticizer resistance> The heat-sensitive recording material was sandwiched between vinyl chloride wraps, and a load of 300 g / cm ² was applied from above to the temperature of 40 ° C. for 2 hours.
After leaving for 4 hours, the densities of the printed portion and the unprinted portion (background) were visually evaluated after standing, and those having little decoloration of the print density were regarded as having good print storability. In addition, a material having less scalp was regarded as having good storability. <Melting point> Melting point measuring machine YAZAWA TYPE BY-
Using No. 2, the temperature was raised at a rate of about 1 ° C./min while observing under a microscope, and the temperature at which melting began was visually judged. <Infrared absorption spectrum> Measured using IR-810 manufactured by JASCO Corporation.

[0078]

Example 1 2,4-Toluene diisocyanate 100
g of toluene as a solvent, and water 30
g was added and reacted at 30 ° C. for 7 hours. The precipitated white solid was collected by filtration, washed with hexane, and vacuum dried overnight to obtain 90 g of a white crystalline compound. The melting point and infrared absorption spectrum of this compound were measured. Melting point is 190 ° C
Met. The infrared absorption spectrum was 1590, 165
A characteristic sharp peak was observed at around 0,2290 cm ^-1 .

Next, 6 g of this compound was taken, and 2.5% by weight
The mixture was pulverized and dispersed for 45 minutes with a paint shaker together with 24 g of an aqueous polyvinyl alcohol solution to obtain a dispersion. Also,
70 g of 3-dibutylamino-6-methyl-7-anilinofluoran and 130 g of a 4.3% by weight aqueous solution of polyvinyl alcohol are sand-grindered (vessel capacity 40).
0 ml, manufactured by IMEX Co., Ltd.) and crushed and dispersed at a rotation speed of 2000 rpm for 3 hours to obtain a dispersion.

Further, 70 g of 4,4'-dihydroxydiphenyl sulfone was mixed with 130 g of a 5.4% by weight aqueous solution of polyvinyl alcohol in a sand grinder (vessel capacity 400 ml, manufactured by Imex Co., Ltd.), and the number of rotations was 2,000 rpm.
m for 3 hours and dispersed to obtain a dispersion. Further, 20 g of calcium carbonate was mixed with 60 g of water, and the mixture was stirred and dispersed with a stirrer to obtain a dispersion.

The coating liquid was composed of 20 parts by weight of the above compound dispersion,
-Dibutylamino-6-methyl-7-anilinofluorane dispersion 10 parts by weight, 4,4'-dihydroxydiphenylsulfone dispersion 20 parts by weight, calcium carbonate dispersion 2
0 parts by weight, 10 parts by weight of a zinc stearate dispersion having a solids concentration of 31.5% by weight, and 36 parts by weight of a 15% by weight polyvinyl alcohol were further mixed and stirred to obtain a mixture.

This coating solution was coated on a base paper having a weighing of 50 g / m ² by a rod number 10 of a bacoater, dried and treated with a super calender to obtain a heat-sensitive recording material. The evaluation result of the sensitivity was as good as the optical density of 1.2. The evaluation result of the covering property with the vinyl chloride wrap was good with little discoloration. The printed portion was also legible and good. The results are summarized in Table 1.

[0083]

Examples 2 to 4 In place of 4,4-dihydroxydiphenylsulfone used in Example 1, 4,4'-dihydroxybenzophenone (Example 2), 4,4-dihydroxydiphenyl ether (Example 3), N-butyl 4'-dihydroxydiphenylacetate (Example 4), 4,4 '
A heat-sensitive recording material was prepared and evaluated in the same manner as in Example 1 except that thiodiphenol (Example 5) was used.
The results are summarized in Table 1.

[0084]

EXAMPLE 6 2,4-Toluene diisocyanate 140
g was dissolved in 200 g of toluene, 74 g of aniline was gradually added, and the mixture was reacted at room temperature for 1 hour to precipitate white crystals. The precipitated white solid was collected by filtration, washed with hexane, and dried in vacuo overnight to give compound 95 as white crystals.
g was obtained. The melting point was 170 ° C. Further, in the infrared absorption spectrum, characteristic sharp peaks were observed around 1600, 1650 and 2290 cm ^-1 .

Next, 6 g of this compound was taken, and 2.5% by weight
The mixture was pulverized and dispersed for 45 minutes with a paint shaker together with 24 g of an aqueous polyvinyl alcohol solution to obtain a dispersion. Subsequently, a heat-sensitive recording material was prepared and evaluated in the same manner as in Example 1 except that a dispersion of the above compound was used instead of the dispersion of the compound obtained in Example 1. The results are summarized in Table 1.

[0086]

Example 7 2,4-Toluene diisocyanate 100
g and 100 g of pyridine were dissolved in 33 g of toluene and reacted at room temperature for 24 hours. After the generated precipitate was filtered, the precipitate was washed with hexane and dried under vacuum overnight to obtain 40 g of an off-white compound. Melting point was 160 ° C. In the infrared absorption spectrum, characteristic sharp peaks were observed at around 1760 and 2290 cm ^-1 .

Next, 6 g of this compound was taken, and 2.5% by weight
The mixture was pulverized and dispersed for 45 minutes with a paint shaker together with 24 g of an aqueous polyvinyl alcohol solution to obtain a dispersion. Subsequently, a heat-sensitive recording material was prepared and evaluated in the same manner as in Example 1 except that a dispersion of the above compound was used instead of the dispersion of the compound obtained in Example 1. The results are summarized in Table 1.

[0088]

Example 8 Diphenylmethane diisocyanate 100
Then, 30 g of trimethyl phosphate and 30 g of ethylene glycol diacetate were added as solvents, and 1.44 g of water was added thereto, followed by a reaction at 30 ° C. for 60 minutes. The precipitated white solid was collected by filtration, washed with hexane, and dried in vacuo overnight to obtain 13 g of a white crystalline compound. The melting point and infrared absorption spectrum of this compound were measured. The melting point was raised to 480 ° C., but was altered and showed no melting point. The infrared absorption spectrum is
Characteristic sharp peaks were observed around 1540, 1600 and 2290 cm ^-1 .

Next, 6 g of this compound was taken, and 2.5% by weight
The mixture was pulverized and dispersed for 45 minutes with a paint shaker together with 24 g of an aqueous polyvinyl alcohol solution to obtain a dispersion. Subsequently, a heat-sensitive recording material was prepared and evaluated in the same manner as in Example 1 except that a dispersion of the above compound was used instead of the dispersion of the compound obtained in Example 1. The results are summarized in Table 1.

[0090]

Example 9 4,4 ', 4 "-triisocyanate-
Take 6 g of 2,5-dimethoxytriphenylamine,
The mixture was crushed and dispersed for 45 minutes with a paint shaker together with 24 g of a 2.5% by weight aqueous solution of polyvinyl alcohol.
A 4 ′, 4 ″ -triisocyanate-2,5-dimethoxytriphenylamine dispersion was obtained.

Subsequently, instead of the dispersion of the compound obtained in Example 1, the above 4,4 ′, 4 ″ -triisocyanato-2,5-dimethoxytriphenylamine dispersion was used, and 3-dibutyl Same as Example 1 except that 3- (N-ethyl-N-isopentylamino) -6-methyl-7-anilinofluoran was used instead of amino-6-methyl-7-anilinofluoran. To prepare a heat-sensitive recording material for evaluation. The results are summarized in Table 1.

[0092]

Examples 10 to 12 70 g of diphenyl sulfone was added to 5.
The dispersion was added to 130 g of a 4% by weight aqueous solution of polyvinyl alcohol, pulverized with a sand grinder (Vessel capacity: 400 ml, manufactured by IMEX Co., Ltd.) at 2,000 rpm for 3 hours to obtain a dispersion. A heat-sensitive recording material was prepared and evaluated in the same manner as in each example except that the obtained dispersion was added to the coating liquid described in Examples 1, 2, and 6 at a ratio of 30 parts by weight. The results are summarized in Table 1.

[0093]

Examples 13 and 14 2 g of di-n-octyltin oxide (Stann OO manufactured by Sankyoki Seikagaku Co., Ltd.) was added to 4 g of a 2.5% by weight aqueous solution of polyvinyl alcohol and 2 g of water.
The mixture was dispersed with 75 g and 1.25 g of ethanol on a paint shaker for 4 hours to obtain a dispersion. The obtained di-n
A heat-sensitive recording material was prepared and evaluated in the same manner as in each of the examples except that the octyltin oxide dispersion was added in a proportion of 2 parts by weight to the coating liquids described in Examples 1 and 10. The results are summarized in Table 1.

[0094]

[Comparative Examples 1 and 2] 4, used in Examples 1 and 9
4 instead of 4'-dihydroxydiphenylsulfone
Except that 4'-dihydroxydiphenyl-2,2'-propane was used, a heat-sensitive recording material was prepared and evaluated in the same manner as in each example. The results are summarized in Table 1.

[0095]

Comparative Examples 3-6 4,4'- used in Example 1
Instead of dihydroxydiphenyl sulfone, benzyl 4-hydroxybenzoate (Comparative Example 3), methyl 4-hydroxybenzoate (Comparative Example 4), 4,4′-biphenol (Comparative Example 5), and salicylanilide (Comparative Example 6) were used. Except for using, a thermosensitive recording material was prepared in the same manner as in each example,
An evaluation was performed. The results are summarized in Table 1.

[0096]

Comparative Examples 7-9 2,4-Toluene diisocyanate 1
To 40 g, 30 g of trimethyl phosphate and 30 g of ethylene glycol diacetate as solvents were added, and 0.29 g of water was added thereto, followed by reaction at 130 ° C. for 2 hours. After the reaction, toluene was added to the residue obtained by distillation under reduced pressure to dissolve the residue, and then hexane was added to precipitate white crystals. The precipitated white solid was collected by filtration, washed with hexane, and dried under vacuum overnight to obtain 7 g of a white compound. Next, this compound was used in place of the isocyanate compound used in Example 1, and 4,4′-dihydroxydiphenyl-2,2′- was used instead of 4,4′-dihydroxydiphenylsulfone.
A heat-sensitive recording material was prepared in the same manner as in Example 1, except that propane (Comparative Example 7), benzyl 4-hydroxybenzoate (Comparative Example 8), and methyl 4-hydroxybenzoate (Comparative Example 9) were used. An evaluation was performed. The results are summarized in Table 1.

[0097]

Comparative Examples 10 to 11 Thermosensitive recording materials were prepared and evaluated in the same manner as in each of the examples except that the isocyanate compound used in the examples 1 and 10 was not used.
The results are summarized in Table 1.

[0098]

[Table 1]

[0099]

By using a specific hydroxyl group-containing compound and an isocyanate compound as a thermosensitive coloring agent, a thermosensitive recording material having excellent image storability and sensitivity can be obtained.

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[Procedure amendment]

[Submission date] January 18, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0083

[Correction method] Change

[Correction contents]

[0083]

Examples 2 to 5 Instead of 4,4-dihydroxydiphenylsulfone used in Example 1, 4,4'-dihydroxybenzophenone (Example 2), 4,4-dihydroxydiphenyl ether (Example 3), N-butyl 4'-dihydroxydiphenylacetate (Example 4), 4,4 '
A heat-sensitive recording material was prepared and evaluated in the same manner as in Example 1 except that thiodiphenol (Example 5) was used.
The results are summarized in Table 1.

Claims (9)

[Claims] 1. A thermosensitive color former comprising an isocyanate compound, a colorless or pale-colored electron-donating dye precursor and a hydroxyl-containing compound represented by the following formula (I). Embedded image (Wherein, Y ₁ represents —SO ₂ —, — (S) _q —, —O—,
—CO— or —CH (COOY ₂ ) —.
q is 1 or 2. Y ₂ is an alkyl group. m and n are each an integer of 0 to 3 and (m + n) ≧ 1. Further, the hydrogen atom of the benzene ring may be substituted by a halogen atom or an aliphatic compound residue or an inorganic compound residue which may have a substituent. ) 2. The thermosensitive color former according to claim 1, wherein the isocyanate compound is an isocyanate adduct compound having a melting point of 40 ° C. or higher. 3. An isocyanate compound represented by the following formula (II):
The thermosensitive coloring agent according to claim 1, which is an isocyanate adduct compound represented by the formula: Embedded image (Here, n represents an integer of 1 to 2. The hydrogen atom of the benzene ring may be substituted with an aromatic compound residue, an aliphatic compound residue, or a heterocyclic compound residue. May have a substituent.) 4. An isocyanate compound represented by the following formula (II)
The heat-sensitive color former according to claim 1, which is an isocyanate adduct compound represented by I). Embedded image (In the formula, m represents an integer of 0 to 5, n represents 1 or 2. Further, the hydrogen atom of the benzene ring is substituted with an aromatic compound residue, an aliphatic compound residue, or a heterocyclic compound residue. Each residue may have a substituent, and X ₁ and X ₂ are each independently —SO ₂ —, —O—,
-(S) _q -,-(CH ₂ ) _q- , -CO-, -CON
_{H -, - CH (C 6} H 5) -, - C (CH 3) 2 - shows the case where either or not present. q is 1 or 2
It is. ) 5. An isocyanate compound represented by the following formula (IV):
The heat-sensitive color former according to claim 1, which is an isocyanate compound represented by any one of (I) to (XII). Embedded image (Here, m represents an integer of 1 to 4. Y ₃ represents a hydrogen atom or a formula (a). R ₁ represents a formula (b) or a formula (c). The following formulas (V) to (XII) The same applies to the following. Embedded image (Here, n represents an integer of 1 to 2. The hydrogen atom of the benzene ring may be substituted with an aromatic compound residue, an aliphatic compound residue, or a heterocyclic compound residue. May have a substituent.) (In the formula, m represents an integer of 0 to 5, n represents 1 or 2. Further, the hydrogen atom of the benzene ring is substituted with an aromatic compound residue, an aliphatic compound residue, or a heterocyclic compound residue. Each residue may have a substituent, and X ₁ and X ₂ are each independently —SO ₂ —, —O—,
-(S) _q -,-(CH ₂ ) _q- , -CO-, -CON
_{H -, - CH (C 6} H 5) -, - C (CH 3) 2 - shows the case where either or not present. q is 1 or 2
It is. )) (R ₂ represents an aromatic compound residue, a heterocyclic compound residue, or an aliphatic compound residue. Further, each residue may have a substituent. The following formulas (VI) and (VII) , (V
Same in III). ) Embedded image Embedded image Embedded image Embedded image (R ₃ represents an aromatic compound residue, a heterocyclic compound residue, or an aliphatic compound residue. Further, each residue may have a substituent.) (R ₄ represents an aromatic compound residue which may have a substituent, a heterocyclic compound residue which may have a substituent, or an aliphatic compound residue or an inorganic compound residue which may have a substituent. )) (R ₅ and R ₆ each independently represent an aromatic compound, a heterocyclic compound, or an aliphatic compound residue. Each residue may have a substituent. R ₅ and R ₆ are mutually cyclic. A structure may be formed.) 6. The method according to claim 1, wherein R ₁ is the following formula (d) or the following formula (e)
The thermosensitive coloring agent according to claim 5, which is represented by the following formula: Embedded image Embedded image 7. The heat-sensitive color former according to claim 1, further comprising an aromatic compound represented by the following formula (XIII). Embedded image (Wherein Y ₄ represents —SO ₂ —, — (S) _q —, —O—,
_{-CH (C 6 H 5) -} , - C (CH 3) 2 -, - CO
-, -OCOO-, -COCO-, -NH-, -COC
H ₂ CO- either, or shows a case that does not exist.
(Q is 1 or 2.) Further, the hydrogen atom of the benzene ring may be substituted by a halogen atom, an aromatic compound residue, an aliphatic compound residue or a hetero compound residue. ) 8. The thermosensitive coloring agent according to claim 1, which contains an organotin compound. 9. A heat-sensitive recording material comprising a support provided with a heat-sensitive coloring layer containing the heat-sensitive coloring agent according to claim 1.