JP2005138543A - Recording material and recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording material whose whiteness degree is enhanced, and a recording method therefor. <P>SOLUTION: The recording material, whose substrate is provided with a recording layer, has a layer containing a fluorescent brightening agent precursor for producing a fluorescent brightening agent by heating. The recording method comprises a process for recording an image on the recording layer of the recording material, and a process for producing the fluorescent brightening agent from the fluorescent brightening agent precursor by fully heating the recording material before or after the image is recorded. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a recording material, in particular, a recording material having improved whiteness and a recording method.

Several thermal recording methods for obtaining a full color image are known, but it is generally difficult to obtain a full color image by the direct thermal method, and some ingenuity is required.
Various studies have been conducted so far to obtain a full-color image by a direct thermal method. For example, Patent Document 1 discloses a coloring layer in which an electron-donating colorless dye precursor and an electron-accepting compound are combined, two diazonium salt compounds with different photosensitive wavelengths, and different diazonium salt compounds reacting with different hues. There has been proposed a method of obtaining a full color by a direct thermal method by using two coloring layers combined with a coupler that develops color, and a total of three coloring layers.

However, when a full color is obtained by the direct thermal method, the white background portion (the portion where the image is not formed) is likely to generate a colored substance (stain) due to the action of light or heat because it is applied to the entire surface of the material forming the image. There was a problem.
Such stains cause quality deterioration such as the loss of color balance of the image, and improvement has been demanded.

As a method for increasing the whiteness of the white background portion, it is effective to introduce a fluorescent brightener into the recording material.
Whiteness enhancement technology by fluorescent whitening is a general technique used for plain paper and fiber techniques, but methods directly applied to heat-sensitive full-color recording materials are disclosed in Patent Documents 2 to 4.
Although these techniques are effective, when trying to apply directly to a heat-sensitive full-color recording material, because the fluorescent whitening agent has ultraviolet absorption, it overlaps with the photosensitive wavelength range of the diazonium salt compound, There is a problem in that part of the light at the time of fixing the diazonium salt compound is absorbed to prevent the light fixing of the diazonium salt compound. For these reasons, there is a limit to the amount of fluorescent whitening agent used.
On the other hand, a method for increasing the whiteness of a recording material by adding a fluorescent whitening agent precursor to the recording material and generating the fluorescent whitening agent by heating the precursor has not been known so far.
JP-A-3-288688 Japanese Patent Laid-Open No. 5-169803 JP 11-286174 A, JP 2000-289338 A

  The present invention has been made on the basis of the above-described demands, and an object thereof is to provide a recording material and a recording method with improved whiteness.

The above-mentioned problems are solved by providing the following recording material and recording method.
(1) A recording material having a recording layer provided on a support, the recording material comprising a layer containing a fluorescent brightener precursor that generates a fluorescent brightener upon heating.
(2) The recording material according to (1), wherein the recording layer is a thermosensitive recording layer, and the thermosensitive recording layer is a diazo thermosensitive recording layer containing a diazonium salt compound and a coupler.
(3) Two diazo thermosensitive recording layers comprising a combination of two diazonium salt compounds having different photosensitive wavelengths and a coupler that reacts with each diazonium salt compound to develop a different hue, and the diazo thermosensitive recording. (1) or (2), wherein the heat-sensitive recording layer different from the layer is formed by laminating the heat-sensitive recording layer and the two diazo heat-sensitive recording layers in the order from the support. The recording material described.

(4) The recording material according to (3) above, wherein one of the two diazonium salt compounds has a maximum absorption wavelength of 445 ± 50 nm and the other has a maximum absorption wavelength of 365 ± 30 nm.
(5) The fluorescent whitening agent is an azomethine compound, and the reaction for producing the azomethine compound is represented by the following reaction formula (1-1) or (1-2): The recording material according to any one of (4) to (4).

In the reaction formula (1-1), Ar ¹ and Ar ² each independently represent a phenyl group or an unsaturated heterocyclic residue which may have a substituent. In the reaction formula (1-2), Ar ¹ represents an optionally substituted phenyl group or an unsaturated heterocyclic residue, and Ar ³ represents an optionally substituted phenylene group. , X represents a single bond or a divalent linking group, and the substituents may form a ring. In the reaction formulas (1-1) and (1-2), L represents a hydrogen atom or a group capable of leaving when an azomethine compound is formed.
(6) Any of the above (1) to (4), wherein the optical brightener is a coumarin compound, and the reaction for producing the coumarin compound is represented by the following reaction formula (2): The recording material according to 1.

In the reaction formula (2), R ¹ represents a hydrogen atom, R ⁴ (R ⁵ ) N—, or an optionally substituted alkyl, alkoxy, aryloxy, alkylthio or arylthio group, and R ² Represents a hydrogen atom, an optionally substituted acyl, alkyl, aryl, alkoxycarbonyl or heterocyclic residue, or a carboxyl group, and R ³ , R ⁴ and R ⁵ are a hydrogen atom or a substituent. An acyl, alkyl, aryl, or heterocyclic residue which may have W represents a carboxyl group, an alkoxycarbonyl group, or a cyano group.
(7) Any of the above (1) to (4), wherein the optical brightener is a styryl compound, and the reaction for producing the styryl compound is represented by the following reaction formula (3): The recording material according to 1.

In the reaction formula (3), Ar ⁴ represents an optionally substituted phenyl group or an unsaturated heterocyclic residue, and R ⁶ represents a hydrogen atom, an optionally substituted alkyl or an aryl group, E ¹ and E ² showing the electron-withdrawing group.
(8) The recording material according to any one of (2) to (7), wherein at least one of the diazonium salt compounds is encapsulated in a microcapsule.
(9) The recording material recording method according to any one of (1) to (8), wherein the recording material is heated entirely before or after image recording on the recording layer. And a method for producing a fluorescent brightener from the fluorescent brightener precursor.

  In the recording material of the present invention, the fluorescent whitening agent precursor that generates the fluorescent whitening agent by heating is included in the recording material. By using this recording material, the white background portion is not extended without extending the fixing time (printing time). High whiteness image recording is possible.

The recording material of the present invention is described in detail below. First, a fluorescent whitening agent precursor that generates a fluorescent whitening agent upon heating will be described.
(Fluorescent brightener precursor that generates fluorescent brightener upon heating)
The fluorescent whitening agent precursor that generates a fluorescent whitening agent upon heating refers to two or more reaction components that generate a fluorescent whitening agent upon heating and react upon heating, and these are not particularly limited, Azomethine-based, bisazomethine-based, coumarin-based, and styryl-based fluorescent enhancements produced according to the reaction formulas represented by formula (1-1) or (1-2), reaction formula (2), or reaction formula (3), respectively. What produces a white agent is preferable.
In the present invention, the fluorescent whitening agent precursor is preferably two reaction components involved in each of the above reaction formulas. Hereinafter, the notation of the fluorescent whitening agent precursor is based on the combination of the two reaction components. For example, in the case of reaction formulas (1-1) and (1-2), a specific example of a formyl compound is represented by “FA-1”, a specific example of an amino compound is represented by “FB-1”, and a fluorescent whitening agent precursor is represented. The body is represented as [(FA-1)-(FB-1)]. In the present specification, “FA-1” and “FB-1” alone may be referred to as a fluorescent brightener precursor.

(1) When an azomethine-based or bisazomethine-based fluorescent whitening agent is produced according to the following reaction formula (1-1) or (1-2)

In the reaction formula (1-1), Ar ¹ and Ar ² each independently represent a phenyl group or an unsaturated heterocyclic residue which may have a substituent. In the reaction formula (1-2), Ar ¹ represents an optionally substituted phenyl group or an unsaturated heterocyclic residue, and Ar ³ represents an optionally substituted phenylene group. , X represents a single bond or a divalent linking group, and the substituents may form a ring. In the reaction formulas (1-1) and (1-2), L represents a hydrogen atom or a group capable of leaving when an azomethine compound is formed.

In the reaction formulas (1-1) and (1-2), when Ar ^{1 to} Ar ³ have a substituent, the substituent includes an alkyl group having 1 to 10 carbon atoms and an alkoxy group having 1 to 10 carbon atoms. , A hydroxy group, an amino group, a substituted amino group having 1 to 16 carbon atoms, an acyl group having 2 to 10 carbon atoms, a cyano group, and a halogen atom are preferable. Of these, a hydroxy group and a substituted amino group are particularly preferred, and the substitution position of the phenyl group is preferably an ortho position with respect to the formyl group (—CHO).

  The unsaturated heterocyclic ring of the unsaturated heterocyclic residue includes an unsaturated bond as a heterocyclic ring bond, and specific examples of the group include the following.

Next, preferred examples of —Ar ³ —X—Ar ³ — in the reaction formula (1-2) are shown below, but are not limited thereto.

  Next, although the preferable example of the formyl compound (henceforth "FA compound") in Reaction formula (1-1) and (1-2) is shown below, it is not limited to these.

  Next, preferred examples of the amino compound (hereinafter sometimes referred to as “FB compound”) to be reacted with the formyl compound in the reaction formulas (1-1) and (1-2) are shown below, but are limited thereto. It is not a thing.

A preferred combination (fluorescent brightener precursor) of a formyl compound (FA compound) and an amino compound (FB compound) used in the fluorescent whitening agent generation reaction used in the recording material of the present invention is the FA compound number and the FB compound. Indicated by number.
(FA-5) / (FB-8), (FA-5) / (FB-9), (FA-5) / (FB-13), (FA-5) / (FB-14), (FA -7) / (FB-9), (FA-7) / (FB-11), (FA-8) / (FB-9), (FA-9) / (FB-9), (FA-15) ) / (FB-8)
(2) When a coumarin fluorescent whitening agent is produced by the following reaction formula (2)

In the reaction formula (2), R ¹ represents a hydrogen atom, R ⁴ (R ⁵ ) N—, or an optionally substituted alkyl, alkoxy, aryloxy, alkylthio or arylthio group, and R ² Represents a hydrogen atom, an optionally substituted acyl, alkyl, aryl, alkoxycarbonyl or heterocyclic residue, or a carboxyl group, and R ³ , R ⁴ and R ⁵ are a hydrogen atom or a substituent. An acyl, alkyl, aryl, or heterocyclic residue which may have W represents a carboxyl group, an alkoxycarbonyl group, or a cyano group.

  In the above formula, the heterocyclic residue may have a substituent on the ring, or may have a condensed ring structure with another ring.

In the above formula, the alkyl group represented by R ¹ to R ^5, preferably an alkyl group having 1 to 10 carbon atoms. Examples of such an alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a t-butyl group, a pentyl group, a hexyl group, a heptyl group, and an n-octyl group. , 2-ethylhexyl group, t-octyl group, nonyl group, decyl group and the like.

  The alkyl group may further have a substituent. Examples of the substituent include a phenyl group, a halogen atom, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, and a carboxyl group. An acid group, a sulfonic acid group or a heterocyclic group is preferred.

As the (substituted) alkyl group represented by R ^{1 to} R ⁵ , a methyl group, an ethyl group, a normal propyl group, an isopropyl group, a normal butyl group, an isobutyl group, a tertiary butyl group pentyl group, a cyclopentyl group, a hexyl group, Cyclohexyl, heptyl, octyl, tertiary octyl, 2-ethylhexyl, decyl, 2-hydroxyethyl, 2-benzoyloxyethyl, benzyl, allyl, methoxyethyl, ethoxyethyl, dibutylamino A carbonylmethyl group is preferred.

The alkoxy group represented by R ¹ is preferably an alkoxy group having 1 to 10 carbon atoms in total. The alkoxy group may have a substituent. Examples of (substituted) alkoxy groups include methoxy, ethoxy, n-propyloxy, isopropyloxy, n-butyloxy, n-hexyloxy, n-octyloxy, 2-ethylhexyloxy, 3,5,5-trimethylhexyloxy. N-decyloxy, cyclohexyloxy, benzyloxy, allyloxy, 2-methoxyethoxy, 2-ethoxyethoxy, 2-phenoxyethoxy, 2-benzoyloxyethoxy, methoxycarbonylmethyloxy, methoxycarbonylethyloxy, butoxycarbonylethyloxy, 2 -An isopropyloxyethyloxy group is preferred.

The aryloxy group represented by R ¹ is preferably an aryloxy group having 6 to 10 carbon atoms in total. The aryloxy group may have a substituent or may be unsubstituted. As the (substituted) aryloxy group, for example, phenyloxy, 4-methylphenyloxy, 3-methylphenyloxy, 2-methylphenyloxy, 4-chlorophenyloxy and 2-chlorophenyloxy are preferable.

The alkylthio group represented by R ¹ is preferably an alkylthio group having 1 to 10 carbon atoms in total. The alkylthio group may have a substituent. Examples of the alkylthio group include methylthio, ethylthio, propylthio, isopropylthio, n-butylthio, sec-butylthio, pentylthio, hexylthio, heptylthio, n-octylthio, 2-ethylhexylthio, t-octylthio, nonylthio, decylthio and the like. .

The arylthio group represented by R ¹ is preferably an arylthio group having 6 to 10 carbon atoms in total. The arylthio group may have a substituent or may be unsubstituted. As the (substituted) arylthio group, for example, phenylthio, 4-methylphenylthio, 3-methylphenylthio, 2-methylphenylthio, 4-chlorophenylthio and 2-chlorophenylthio groups are preferable.

The acyl group represented by R ^{2 to} R ⁵ is preferably an acyl group having 2 to 20 carbon atoms, and the portion other than the carbonyl group of the acyl group may be an aliphatic, aromatic, or heterocyclic group, and further a substituent. The substituent may be an alkoxy group, an aryloxy group, or a halogen atom. As the acyl group, an acetyl group, a propanoyl group, a hexanoyl group, an octanoyl group, a decanoyl group, a benzoyl group, a phenoxyacetyl group, and a 2-ethylhexanoyl group are particularly preferable.

The aryl group represented by R ^{2 to} R ⁵ is preferably an aryl group having 6 to 10 carbon atoms, and examples thereof include phenyl and naphthyl groups.
The aryl group may further have a substituent. Examples of the substituent include a phenyl group, a halogen atom, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, Examples thereof include a carboxylic acid group, a sulfonic acid group, and a heterocyclic group. As the (substituted) aryl group represented by R ^{2 to} R ⁵ , phenyl group, 4-chlorophenyl group, 4-methylphenyl group, 4-butoxyphenyl group, 2-methoxyphenyl group, 2-hydroxyphenyl group, A 2-hydroxy-5-butoxyphenyl group is preferred.

In the above formula, examples of the heterocyclic residue represented by R ^{2 to} R ⁵ include the following groups.

Examples of the alkoxy group of the alkoxycarbonyl group represented by R ² include 2,6-di-t-butyl-4-methyl-cyclohexyloxy and the like in addition to the alkoxy group represented by R ¹ .

Examples of the alkoxycarbonyl group represented by W include the alkoxycarbonyl group represented by R ² .

  Specific examples of the two reaction components (hereinafter sometimes referred to as “FC compound” and “FD compound”) used in the reaction formula (2) are shown below, but are not limited thereto.

Next, a preferred combination of the two reaction components (fluorescent brightener precursors) used in the fluorescent whitening agent generation reaction represented by the reaction formula (2) is shown by combining the FC compound number and the FD compound number. .
(FC-1) / (FD-8), (FC-1) / (FD-9), (FC-1) / (FD-6), (FC-2) / (FD-8), (FC -2) / (FD-10), (FC-3) / (FD-6), (FC-6) / (FD-11), (FC-13) / (FD-10)

(3) When a styryl fluorescent whitening agent is produced by the following reaction formula (3)

In the reaction formula (3), Ar ⁴ represents an optionally substituted phenyl group or an unsaturated heterocyclic residue, and R ⁶ represents a hydrogen atom, an optionally substituted alkyl or an aryl group, E ¹ and E ² showing the electron-withdrawing group.
As the substituent when Ar ⁴ has a substituent, the alkyl group having 1 to 10 carbon atoms, the alkoxy group having 1 to 10 carbon atoms, the hydroxy group, the amino group, the substituted amino group having 1 to 16 carbon atoms, the number of carbon atoms 2-10 acyl groups, cyano groups and halogen atoms are preferred. Of these, a hydroxy group and a substituted amino group are particularly preferable, and the phenyl group is preferably substituted at the ortho position with respect to the —C (═O) —R ⁶ group.
When R < ⁶ > represents an alkyl group, a C1-C4 alkyl group is preferable. In addition, when R ⁶ represents an aryl group, a phenyl group is preferable. The alkyl group is further substituted with a phenyl group, a halogen atom, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, an acyloxy group, an acylamino group, a carbamoyl group, a cyano group, a carboxylic acid group, a sulfonic acid group, or a heterocyclic group. In addition, when R ⁶ is an aryl group, it may be similarly substituted with a substituent when Ar ⁴ has a substituent.
In addition, when Ar ⁴ represents an unsaturated heterocyclic residue, the unsaturated heterocyclic ring of the unsaturated heterocyclic residue includes an unsaturated bond as a heterocyclic ring bond, and specific examples thereof include the above This is the same as the specific examples of the unsaturated heterocyclic residue mentioned for Ar ¹ and Ar ² in Reaction Formula (1).

  Preferred examples of the formyl compound or ketone compound (hereinafter sometimes referred to as “FE compound”) in Reaction Formula (3) are shown below, but are not limited thereto.

In the reaction formula (3), E ¹ and E ² represent electron withdrawing groups. The electron-withdrawing group means a substituent having a positive Hammett σp value, which may be the same or different. For example, acetyl group, propionyl group, pivaloyl group, chloroacetyl group, trichloro group Acyl groups such as acetyl group, trifluoroacetyl group, 1-methylcyclopropylcarbonyl group, 1-ethylcyclopropylcarbonyl group, 1-benzylcyclopropylcarbonyl group, benzoyl group, 4-methoxybenzoyl group, thenoyl group; methoxycarbonyl Groups, ethoxycarbonyl groups, 2-methoxyethoxycarbonyl groups, 4-methoxyphenoxycarbonyl groups and the like; carbamoyl groups, N, N-dimethylcarbamoyl groups, N, N-diethylcarbamoyl groups, N-phenylcarbamoyl groups, N- [2,4-bis ( Nthyloxy) phenyl] carbamoyl group, N- [2,4-bis (octyloxy) phenyl] carbamoyl group, carbamoyl group such as morpholinocarbonyl group; alkylsulfonyl group such as methanesulfonyl group, benzenesulfonyl group, toluenesulfonyl group or aryl Sulfonyl group; phosphono group such as diethylphosphono group; benzoxazol-2-yl group, benzothiazol-2-yl group, 3,4-dihydroquinazolin-4-on-2-yl group, 3,4-dihydroquinazoline A heterocyclic group such as a -4-sulfon-2-yl group; a heterocyclic group; a nitro group; an imino group; and a cyano group are preferable.

Further, the electron-withdrawing groups represented by E ¹ and E ² may be bonded to form a ring. The ring formed by E ¹ and E ² is preferably a 5- to 6-membered carbocyclic or heterocyclic ring.

Specific examples of the compound represented by E ¹ —CH ₂ —E ² (hereinafter sometimes referred to as “FF compound”) are shown below, but are not limited thereto.

Next, a preferred combination of two reaction components (fluorescent brightener precursors) used in the fluorescent whitening agent generation reaction represented by the reaction formula (3) is shown by the combination of the FC compound number and the FD compound number. .
(FE-5) / (FF-7), (FE-5) / (FF-8), (FE-4) / (FF-11), (FE-9) / (FF-18), (FE -8) / (FF-21), (FE-6) / (FF-26), (FE-5) / (FF-27)

The proportions of the two components used in each of the optical brightener generating reactions are FA compounds in three combinations of [FA compound-FB compound], [FC compound-FD compound], and [FE compound-FF compound]. (The FC compound and the FE compound are the same.) The FB compound (the FD compound and the FF compound are the same) is 0.1 to 10 mol, preferably about 0.5 to 5 mol, per 1 mol. (However, in the case of reaction formula (1-2), the amount of the FB compound is 0.05 to 5 mol, preferably about 0.25 to 2.5 mol with respect to 1 mol of the FA compound.)
The coating amount of the FA compound or FF compound is preferably in the range of 0.02 to 0.50 mmol / m ² , particularly preferably 0.05 to 0.25 mmol / m ² .

  In the recording material, the FA compound, FC compound or FE compound is preferably isolated from the FB compound, FD compound or FF compound, respectively. As an isolation method, for example, a method of isolating a color forming component contained in the recording layer, for example, a diazonium salt compound and a coupler, can be similarly used. Specifically, (A) FA compound, FC compound or FE compound (hereinafter simply referred to as “FA compound etc.”) and FB compound, FD compound or FF compound (hereinafter simply referred to as “FB compound etc.”). A method of separating both by solid dispersion, (B) a method of encapsulating an FA compound or the like in a microcapsule, and emulsifying and dispersing or solid dispersing the FB compound or the like, (C) an FA compound or the like, and A method such as a method of separating both the FB compound and the like by encapsulating them in a microcapsule is preferably used.

  For the method of solid-dispersing the fluorescent whitening agent precursor, the method of emulsifying and dispersing, and the method of encapsulating in the microcapsule, the solid component dispersing method, emulsifying dispersion method, and microencapsulation method described below can be used in the same manner. it can.

The optical brightener precursor may be contained in any layer of the recording material. It may be added to the recording layer or contained in a layer different from the recording layer.
For example, a thermal recording layer [leuco-based coloring component (electron-donating dye precursor and electron-accepting compound) or diazo-based coloring component (diazonium salt compound and coupler) is included on the side closest to the support. A diazo thermosensitive recording layer comprising a combination of two diazonium salt compounds having different photosensitive wavelengths and a coupler that reacts with each diazonium salt compound and develops a different hue on the thermosensitive recording layer In the case of a multicolor thermosensitive recording material provided with a fluorescent whitening agent, it is possible to add a fluorescent whitening agent precursor to the thermosensitive recording layer closest to the support (usually, the recording energy is higher on the side closer to the support). This is preferable because there is no fixing step of the diazonium salt compound after the agent is formed.
In addition, a fluorescent whitening agent precursor may be added to an intermediate layer between the heat-sensitive recording layer and the heat-sensitive recording layer, and in this case, the heat-sensitive recording layer closest to the support and the heat-sensitive recording formed thereon. It is preferable to add to an intermediate layer between the layers.

[Recording material]
The recording layer in the recording material of the present invention is preferably a thermosensitive recording layer. As the coloring component of the heat-sensitive recording layer, known ones such as a leuco coloring component and a diazo coloring component can be used without limitation.
When the heat-sensitive recording layer contains a diazonium salt compound, fixing is preferably performed after thermal recording. However, in the recording material of the present invention containing a fluorescent whitening agent precursor, a fluorescent whitening agent after fixing may be generated. preferable. This is because there is no ultraviolet absorption by the fluorescent whitening agent at the time of fixing, and the effect that the fixing time is not prolonged is obtained.

(Multicolor thermal recording material)
Further, as the recording material of the present invention, a multicolor thermosensitive recording material provided with a plurality of thermosensitive recording layers that develop colors in mutually different hues can be mentioned. Examples of the multicolor thermosensitive recording material include two diazo thermosensitive recording layers containing a combination of two diazonium salt compounds having different photosensitive wavelengths and couplers that react with the respective diazonium salt compounds to develop different hues, and the diazo thermosensitive recording material. It is preferable to have a heat-sensitive recording layer different from the heat-sensitive recording layer. Further, in the multicolor heat-sensitive recording material, the another heat-sensitive recording layer and the two diazo heat-sensitive recording layers in order from the closest to the support. More preferably, are laminated. The other heat-sensitive recording layer may be a heat-sensitive recording layer containing a diazo color-forming component or a heat-sensitive recording layer containing a leuco color-forming component. It may be a heat-sensitive recording layer containing any color developing component such as a color forming system that reacts with a nucleating agent to generate an elimination reaction and develops color.

  The two diazo thermosensitive recording layers are a thermosensitive recording layer (B layer) containing a diazonium salt compound with a maximum absorption wavelength of 365 ± 30 nm, and a thermosensitive recording layer (C layer) containing a diazonium salt compound with a maximum absorption wavelength of 445 ± 50 nm. Are preferably provided in this order from the support side.

Further, the hue of the heat-sensitive recording material in the present invention is preferably the following combination.
In order from the support side, cyan / magenta / yellow and magenta / cyan / yellow.
In order to prevent color mixing between the heat-sensitive recording layers, an intermediate layer may be provided between the heat-sensitive recording layers.
The intermediate layer is made of a water-soluble polymer compound such as gelatin, phthalated gelatin, polyvinyl alcohol, or polyvinylpyrrolidone, and may contain various additives as appropriate.

If necessary, the multicolor thermosensitive recording material of the present invention preferably further includes a light transmittance adjusting layer or a protective layer, or a light transmittance adjusting layer and a protective layer as an upper layer.
The light transmittance adjusting layer is described in JP-A Nos. 9-39395, 9-39396, and Japanese Patent Application No. 7-208386.
The optical brightener precursor may be contained in the light transmittance adjusting layer.

  When a component that functions as a precursor of an ultraviolet absorber is used in the light transmittance adjustment layer, it does not function as an ultraviolet absorber before irradiating light in a wavelength region necessary for fixing, so that a high light transmittance is obtained. Therefore, when fixing the light-fixing type thermosensitive recording layer, the wavelength of the region necessary for fixing can be sufficiently transmitted, and the visible light transmittance is also high, which may hinder the fixing of the thermosensitive recording layer. Absent.

On the other hand, the precursor of the ultraviolet absorber is irradiated with light in a wavelength region necessary for photofixation (photodecomposition of a diazonium salt compound by light irradiation) of the photofixing type thermosensitive recording layer, and then reacts with the light to cause ultraviolet light. It will function as an absorbent. This ultraviolet absorber absorbs most of the light having a wavelength in the ultraviolet region and lowers its transmittance, thereby making it possible to improve the light resistance of the heat-sensitive recording material. However, since there is no visible light absorptivity, the visible light transmittance is not substantially changed.
The light transmittance adjusting layer can be provided in at least one layer in the heat-sensitive recording material, and in particular, it is preferably formed between the heat-sensitive recording layer and the protective layer. Further, the protective layer may have the function of the light transmittance adjusting layer and may be used in combination.

Next, the coloring components used in the recording layer of the present invention will be described.
(Diazonium salt compound)
As described above, the diazonium salt compound preferably contains a diazonium salt compound having a maximum absorption wavelength of 445 ± 50 nm in one of the two thermosensitive recording layers and a diazonium salt compound having a maximum absorption wavelength of 365 ± 30 nm in the other. .

-Diazonium salt compound with maximum absorption wavelength of 445 ± 50 nm-
When the maximum absorption wavelength exceeds the upper limit, the stability of the diazonium salt compound is deteriorated and the practicality is insufficient, and when it exceeds the lower limit, the maximum absorption wavelength range of 365 ± 30 nm of the diazonium salt compound is not preferable. The range of the maximum absorption wavelength of the diazonium salt compound is more preferably 395 to 475 nm.
The diazonium salt compound having a maximum absorption wavelength of 445 ± 50 nm is preferably a diazonium salt compound represented by the general formulas (1) to (3). Incidentally, the meaning of the following R ^1-symbol is not related to R ¹ and ~ of the fluorescent whitening agent (precursor).

[In General Formulas (1) to (3), R ¹ , R ² , and R ^{4 to} R ⁹ may be the same or different and each represents a hydrogen atom, an alkyl group, or an aryl group, and R ³ represents a hydrogen atom. , An alkyl group, an alkoxy group, a halogen atom, a sulfonyl group, an acyl group, or an alkoxycarbonyl group, D ¹ represents an electron donating group having a Hammett σp value of −0.05 or less, among them, a substituted amino group, An alkylthio group, an arylthio group, an alkoxy group, or an aryloxy group is preferable. X represents a counter anion. A represents an electron-withdrawing group having a Hammett σp value of 0.3 or more. Each benzene ring in the general formulas (1) to (3) may further have a substituent. ]

R ¹ , R ² and R ^{4 to} R ⁹ are preferably a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or an aryl group having 6 to 10 carbon atoms. In particular, a hydrogen atom, a C1-C10 alkyl group, and a phenyl group are preferable. The alkyl group may be branched and may be substituted with a halogen atom, an alkoxy group, an aryloxy group, a phenyl group, an alkoxycarbonyl group, an acyloxy group, or a carbamoyl group. The phenyl group may be substituted with a halogen atom, an alkyl group, an aryl group, an acyloxy group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, or an acyl group.
Specific examples of R ¹ , R ² , R ^{4 to} R ⁹ include the following.

R ³ is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a chlorine atom, a fluorine atom, an alkoxy group having 1 to 15 carbon atoms, an alkylsulfonyl group having 1 to 12 carbon atoms, or an arylsulfonyl having 6 to 18 carbon atoms. Group, an acyl group having 1 to 18 carbon atoms, or an alkoxycarbonyl group having 1 to 18 carbon atoms is preferable. The alkyl group and alkylsulfonyl group may be branched and may be substituted with a halogen atom, an alkoxy group, an aryloxy group, a phenyl group, an alkoxycarbonyl group, an acyloxy group, or a carbamoyl group.
The arylsulfonyl group may be substituted with a halogen atom, an alkyl group, or an alkoxy group.
Specific examples of R ³ include those shown below.

As A, a sulfonyl group, an acyl group, an alkoxycarbonyl group, or a cyano group is preferable. It is synonymous with a sulfonyl group, an acyl group, an alkoxycarbonyl group, a sulfonyl group represented by R ³ , an acyl group, and an alkoxycarbonyl group.
R ⁸ and R ⁹ , R ¹³ and R ¹⁴ may be bonded to each other to form a ring.

Examples of the acid anion X ⁻ include perfluoroalkyl carboxylic acids having 1 to 20 carbon atoms (for example, perfluorooctanoic acid, perfluorodecanoic acid, perfluorododecanoic acid), and perfluoroalkyl sulfonic acids having 1 to 20 carbon atoms. (For example, perfluorooctanesulfonic acid, perfluorodecanesulfonic acid, perfluorohexadecanesulfonic acid), aromatic carboxylic acid having 7 to 50 carbon atoms (for example, 4,4-di-t-butylsalicylic acid, 4-t- Octyloxybenzoic acid, 2-n-octyloxybenzoic acid, 4-t-hexadecylbenzoic acid, 2,4-bis-n-octadecyloxybenzoic acid, 4-n-decylnaphthoic acid), fragrance having 6 to 50 carbon atoms Group sulfonic acids (for example, 1,5-naphthalene disulfonic acid, 4-t-octyloxybenzene sulfone) Acid, 4-n-dodecylbenzenesulfonic acid), 4,5-di -t- butyl-2-naphthoic acid, Tetorafu' boric acid, tetraphenyl borate, etc. hexafluorophosphate and the like. Among them, perfluoroalkylcarboxylic acids having 6 to 16 carbon atoms, aromatic carboxylic acids having 10 to 40 carbon atoms, aromatic sulfonic acids having 10 to 40 carbon atoms, tetrafluoroboric acid, tetraphenylboric acid, hexafluorophosphoric acid Etc. are preferable.

When D ¹ represents a substituted amino group as an electron donating group having a Hammett's σp value of −0.05 or less, the substituted amino group includes an alkylamino group having 1 to 20 carbon atoms, and 2 to 20 carbon atoms. Dialkylamino groups, C6-C10 arylamino groups, C7-C20 N-alkyl-N-arylamino groups, and C2-C20 acylamino groups are preferred. You may have the above substituent. Moreover, substituents, such as the said alkyl group, may couple | bond together and a cyclic amino group may be formed.
When D ¹ represents an alkylthio group as an electron donating group having a Hammett's σp value of −0.05 or less, an alkylthio group having 1 to 18 carbon atoms is preferable, and when an arylthio group is represented, an arylthio group having 6 to 10 carbon atoms is preferable. Group is preferable, when an alkoxy group is represented, an alkoxy group having 1 to 18 carbon atoms is preferable, and when an aryloxy group is represented, an aryloxy group having 6 to 10 carbon atoms is preferable, and these groups further include 1 or 2 or more. It may have a substituent.
From the viewpoint of the stability of the diazonium salt compound, D ¹ is preferably a dialkylamino group, an N-alkyl-N-arylamino group, an acylamino group, an alkylthio group, an arylthio group, an alkoxy group, or an aryloxy group.

As an electron donating group having a Hammett σp value of −0.05 or less represented by D ¹ , an alkyl group and an aryl group in a substituted amino group, an alkylthio group, an arylthio group, an alkoxy group, or an aryloxy group are as follows: The thing is mentioned.

When D ¹ in the general formula (1) represents a substituted amino group, a cyclic amino group formed by bonding of the substituents, and a cyclic group of —N (R ⁸ ) R ^{9 in} the general formula (2) Examples of these include the following.

The benzene ring on the indolyl group of the general formula (3) may have a nuclear substituent, and an electron-withdrawing group is particularly preferable from the viewpoint of ring stability. The Hammett σp value of the electron withdrawing group is preferably 0.1 or more. Among these, an acyl group, a sulfonyl group, an alkoxycarbonyl group, a sulfonamide group, or a carbonamido group is preferable. An acyl group, a sulfonyl group, and an alkoxycarbonyl group have the same meanings as R ³ , and preferred embodiments are also the same. The sulfonamide group preferably has 1 to 12 carbon atoms, and specific examples thereof include the following.

  The carbonamido group preferably has 2 to 13 carbon atoms, and specific examples thereof include the following.

  Specific examples (exemplary compounds (1) to (22)) of the diazonium salt compounds represented by the general formulas (1) to (3) are shown below, but the present invention is not limited to the following.

-Diazonium salt compound with maximum absorption wavelength 365 ± 30 nm-
When the maximum absorption wavelength exceeds the upper limit, the maximum absorption wavelength range of 445 ± 50 nm of the diazonium salt compound is not preferable. If the lower limit is exceeded, the stability and photodegradability of the diazonium salt compound are deteriorated. The range of the maximum absorption wavelength of the diazonium salt compound is more preferably 350 to 375 nm.
The diazonium salt compound having a maximum absorption wavelength of 365 ± 30 nm is preferably a diazonium salt compound represented by the following general formula (4).

In General Formula (4), R ¹⁰ and R ¹¹ have the same meaning as R ¹ , and preferred examples are also the same.

D ² represents an alkoxy group or an aryloxy group. The alkyl group of the alkoxy group and the aryl group of the aryloxy group have the same meanings as the alkyl group and aryl group represented by R ¹ , and preferred examples are also the same.

  Specific examples (exemplary compounds (23) to (29)) of the diazonium salt compound represented by the general formula (4) are listed below, but the present invention is not limited to the following.

  The diazonium salt compound may be either oily or crystalline, but is preferably in a crystalline state at room temperature from the viewpoint of handleability. This diazonium salt compound may be used alone or in combination of two or more, or may be used in combination with an existing diazonium salt compound.

The content of the heat-sensitive recording layer of the diazonium salt compound is preferably 0.02 to 5 g / m ^2, more preferably 0.1-4 g / m ² from the viewpoint of color density.

  In order to stabilize the diazonium salt compound, a complex compound can be formed using zinc chloride, cadmium chloride, tin chloride, or the like to stabilize the diazonium salt compound.

(coupler)
Next, couplers (coupling components) that can be used in the recording material of the present invention will be described.
As the coupler, any compound can be used as long as it forms a dye by coupling with a diazonium salt compound in a basic atmosphere and / or a neutral atmosphere. All so-called 4-equivalent coupler compounds for silver halide photographic light-sensitive materials can be used as couplers. A part of a 2-equivalent coupler can also be used. These can be selected according to the target hue.
For example, there are so-called active methylene compounds having a methylene group next to a carbonyl group, phenol derivatives, naphthol derivatives and the like. Specific examples include the following, which are used within the scope of the object of the present invention.

  Specific examples of the coupler include, for example, resorcin, phloroglucin, 2,3-dihydroxynaphthalene, sodium 2,3-dihydroxynaphthalene-6-sulfonate, 1-hydroxy-2-naphthoic acid morpholinopropylamide, 2-hydroxy- Sodium 3-naphthalenesulfonate, 2-hydroxy-3-naphthalenesulfonic acid anilide, 2-hydroxy-3-naphthalenesulfonic acid morpholinopropylamide, 2-hydroxy-3-naphthalenesulfonic acid-2-ethylhexyloxypropylamide, 2- Hydroxy-3-naphthalenesulfonic acid-2-ethylhexylamide, 5-acetamido-1-naphthol, 1-hydroxy-8-acetamidonaphthalene-3,6-disulfonic acid sodium salt, 1-hydroxy-8-acetate Midonaphthalene-3,6-disulfonic acid dianilide, 1,5-dihydroxynaphthalene, 2-hydroxy-3-naphthoic acid morpholinopropylamide, 2-hydroxy-3-naphthoic acid octylamide, 2-hydroxy-3-naphthoic acid anilide 5,5-dimethyl-1,3-cyclohexanedione, 1,3-cyclopentanedione, 5- (2-n-tetradecyloxyphenyl) -1,3-cyclohexanedione, 5-phenyl-4-methoxy Carbonyl-1,3-cyclohexanedione, 5- (2,5-di-n-octyloxyphenyl) -1,3-cyclohexanedione;

  N, N′-dicyclohexylbarbituric acid, N, N′-di-n-dodecylbarbituric acid, Nn-octyl-N′-n-otatadecylbarbituric acid, N-phenyl-N ′-( 2,5-di-n-octyloxydiphenyl) barbituric acid, N, N′-bis (octadecyloxycarbonylmethyl) barbituric acid, 1-phenyl-3-methyl-5-pyrazolone, 1- (2,4 , 6-trichlorophenyl) -3-anilino-5-pyrazolone, 1- (2,4,6-trichlorophenyl) -3-benzamido-5-pyrazolone, 6-hydroxy-4-methyl-3-cyano-1- (2-ethylhexyl) -2-pyridone, 2,4-bis- (benzoylacetamido) toluene, 1,3-bis- (pivaloylacetamidomethyl) benzene, benzo L-acetonitrile, thenoylacetonitrile, acetoacetanilide, benzoylacetanilide, pivaloylacetanilide, 2-chloro-5- (Nn-butylsulfamoyl) -1-bivaloylacetamidobenzene, 1- (2-ethylhexyloxypropyl) ) -3-Cyano-4-methyl-6-hydroxy-1,2-dihydropyridin-2-one, 1- (dodecyloxypropyl) -3-acetyl-4-methyl-6-hydroxy-1,2-dihydropyridine- 2-one, 1- (4-n-octyloxyphenyl) -3-tert-butyl-5-aminopyrazole and the like can be mentioned.

  The details of the coupler are described in JP-A-4-201483, JP-A-7-223367, JP-A-7-223368, JP-A-7-323660, JP-A-7-125446, JP-A-7-96671, JP-A-7-167671. JP-A-7-223367, JP-A-7-223368, JP-A-9-156229, JP-A-9-216468, JP-A-9-216469, JP-A-9-203472, JP-A-9-319025, JP-A-10 -35113, JP-A-10-193801, JP-A-10-264532, and the like.

Among the above, in the present invention, a compound represented by the following general formula (IV) or a tautomer thereof is particularly preferable.
Hereinafter, the coupler represented by the general formula (IV) will be described in detail.

In general formula (IV), E ¹ and E ² each independently represent an electron-withdrawing group, and X represents a group capable of leaving an azo dye upon azo coupling. E ^{1 and} E ² may combine to form a ring.

The electron-withdrawing group represented by E ¹ and E ² means a substituent having a positive Hammett σp value, which may be the same or different. For example, acetyl group, propionyl Group, pivaloyl group, chloroacetyl group, trichloroacetyl group, trifluoroacetyl group, 1-methylcyclopropylcarbonyl group, 1-ethylcyclopropylcarbonyl group, 1-benzylcyclopropylcarbonyl group, benzoyl group, 4-methoxybenzoyl group An acyl group such as a thenoyl group; an oxycarbonyl group such as a methoxycarbonyl group, an ethoxycarbonyl group, a 2-methoxyethoxycarbonyl group, or a 4-methoxyphenoxycarbonyl group; a carbamoyl group, an N, N-dimethylcarbamoyl group, an N, N- Diethylcarbamoyl group, N-phenylcarbamoyl Carbamoyl groups such as N- [2,4-bis (pentyloxy) phenyl] carbamoyl group, N- [2,4-bis (octyloxy) phenyl] carbamoyl group, morpholinocarbonyl group; methanesulfonyl group, benzenesulfonyl group Alkylsulfonyl group such as toluenesulfonyl group or arylsulfonyl group; phosphono group such as diethylphosphono group; benzoxazol-2-yl group, benzothiazol-2-yl group, 3,4-dihydroquinazolin-4-one- Preferred examples include a heterocyclic group such as a 2-yl group and a 3,4-dihydroquinazolin-4-sulfon-2-yl group; a heterocyclic group; a nitro group; an imino group; and a cyano group.

Further, the electron-withdrawing groups represented by E ¹ and E ² may be bonded to form a ring. The ring formed by E ¹ and E ² is preferably a 5- to 6-membered carbocyclic or heterocyclic ring.

  X represents a group capable of leaving during azo coupling, and examples of the leaving group X include a halogen atom (fluorine, bromine, chlorine, iodine), a substituted alkyl group (hydroxymethyl group, dimethylaminomethyl group), an alkylthio group (for example, , Ethylthio group, 2-carboxyethylthio group, dodecylthio group, 1-carboxydodecylthio group), arylthio group (for example, phenylthio group, 2-butoxy-t-octylphenylthio group), alkoxyl group (for example, ethoxy group, Dodecyloxy group, methoxyethylcarbamoylmethoxy group, carboxypropyloxy group, methylsulfonylethoxy group, ethoxycarbonylmethoxy group), aryloxy group (for example, 4-methylphenoxy group, 4-chlorophenoxy group, 4-methoxyphenoxy group, 4-carboxyphenoxy Group, 3-ethoxycarboxyphenoxy group, 3-acetylaminophenoxy group, 2-carboxyphenoxy group), acyloxy group (for example, acetoxy group, tetradecanoyloxy group, benzoyloxy group), arylsulfonyloxy group (for example, toluene) Sulfonyloxy group), dialkylaminocarbonyloxy group (for example, dimethylaminocarbonyloxy group, diethylaminocarbonyloxy group), diarylaminocarbonyloxy group (for example, diphenylaminocarbonyloxy group), alkoxycarbonyloxy group (for example, ethoxycarbonyloxy group) Group, benzyloxycarbonyloxy group), aryloxycarbonyloxy group (for example, phenoxycarbonyloxy group), or heterocyclic group (for example, imidazolyl group, Razoriru group, triazolyl group, tetrazolyl group).

  Specific examples of the coupler represented by the general formula (IV) are shown below, but the present invention is not limited thereto. The following tautomers of couplers can also be mentioned as suitable.

  The tautomer of the coupler is one that exists as an isomer of the coupler represented by the above, and has a relationship in which the structure easily changes between the two. The coupler used in the present invention As such, the tautomer is also preferable.

(Microencapsulation)
In the recording material of the present invention, the diazonium salt compound is preferably encapsulated in a microcapsule for the purpose of improving the raw storage stability before use. The method for forming the microcapsules can be appropriately selected from known methods.
The polymer substance forming the capsule wall of the microcapsule has a glass transition temperature of 60 to 200 ° C. in particular because it is necessary to have a property of being impermeable at normal temperature and permeable when heated. Preferred examples include polyurethane, polyurea, polyamide, polyester, urea / formaldehyde resin, melamine resin, polystyrene, styrene / methacrylate copolymer, styrene / acrylate copolymer, and mixed systems thereof.

  Specifically, an interfacial polymerization method or an internal polymerization method is suitable as the microcapsule formation method. Details of the capsule forming method and specific examples of the reactant are described in the specifications of US Pat. Nos. 3,726,804 and 3,796,669. For example, when polyurea or polyurethane is used as the capsule wall material, polyisocyanate and a second substance that reacts therewith to form a capsule wall (for example, polyol or polyamine) are mixed in an aqueous medium or an oily medium to be encapsulated. Then, these are emulsified and dispersed in water and then heated to cause a polymer formation reaction at the oil droplet interface to form a microcapsule wall. Polyurea can also be produced when the addition of the second substance is omitted.

  In the present invention, it is preferable that the polymer material forming the capsule wall of the microcapsule contains polyurethane and / or polyurea as components because of excellent manufacturing suitability and thermal response sensitivity.

Next, a method for producing a diazonium salt compound-encapsulating microcapsule (polyurea / polyurethane wall) will be described.
First, the diazonium salt compound is dissolved or dispersed in a hydrophobic organic solvent that becomes the core of the capsule to prepare an oil phase that becomes the core of the microcapsule. At this time, polyisocyanate is further added as a wall material.

  In the preparation of the oil phase, the hydrophobic organic solvent used for forming the core of the microcapsule by dissolving and dispersing the diazonium salt compound is preferably an organic solvent having a boiling point of 100 to 300 ° C., for example, alkylnaphthalene, alkyldiphenyl. Ethane, alkyldiphenylmethane, alkylbiphenyl, alkylterphenyl, chlorinated paraffin, phosphate ester, maleate ester, adipate ester, phthalate ester, benzoate ester, carbonate ester, ether, sulfate ester And sulfonic acid esters. You may use these in mixture of 2 or more types.

When the solubility of the diazonium salt compound to be encapsulated in the organic solvent is inferior, a low-boiling solvent having a high solubility of the diazonium salt compound to be used can be supplementarily used together. For example, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, methylene chloride, tetrahydrofuran, acetonitrile, acetone and the like can be mentioned.
Therefore, the diazonium salt compound preferably has an appropriate solubility in a high boiling hydrophobic organic solvent and a low boiling solvent, and specifically has a solubility of 5% by mass or more in the solvent. It is preferable. The solubility in water is preferably 1% by mass or less.

On the other hand, an aqueous solution in which a water-soluble polymer is dissolved is used for the aqueous phase to be used, and after the oil phase is added thereto, emulsification and dispersion are performed by means of a homogenizer or the like. It facilitates and acts as a dispersion medium for stabilizing the emulsified and dispersed aqueous solution. Here, in order to more uniformly emulsify and disperse and stabilize, a surfactant may be added to at least one of the oil phase and the aqueous phase. As the surfactant, a known emulsifying surfactant can be used.
As addition amount in the case of adding surfactant, 0.1-5 mass% is preferable with respect to the oil phase mass, and 0.5-2 mass% is more preferable.

  The water-soluble polymer used in the water-soluble polymer aqueous solution for dispersing the prepared oil phase is preferably a water-soluble polymer having a solubility in water of 5% by mass or more at the temperature to be emulsified, such as polyvinyl alcohol and its Modified products, polyacrylic acid amide and derivatives thereof, ethylene-vinyl acetate copolymer, styrene-maleic anhydride copolymer, ethylene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, polyvinylpyrrolidone, ethylene -Acrylic acid copolymer, vinyl acetate-acrylic acid copolymer, carboxymethylcellulose, methylcellulose, casein, gelatin, starch derivative, arabic gum, sodium alginate and the like.

  It is preferable that the water-soluble polymer has no or low reactivity with an isocyanate compound. For example, a polymer having a reactive amino group in a molecular chain such as gelatin reacts by being modified in advance. It is preferable to eliminate the property.

The polyvalent isocyanate compound is preferably a compound having a trifunctional or higher functional isocyanate group, but may be a bifunctional isocyanate compound. Specifically, xylene diisocyanate and hydrogenated products thereof, hexamethylene diisocyanate, tolylene diisocyanate and hydrogenated products thereof, diisocyanates such as isophorone diisocyanate, and the like, and these dimers or trimers (burette or isocyanate). Nurate), other polyfunctional adducts of polyols such as trimethylolpropane and bifunctional isocyanates such as xylylene diisocyanate, adducts of polyols such as trimethylolpropane and bifunctional isocyanates such as xylylene diisocyanate Examples thereof include a compound in which a high molecular weight compound such as polyether having active hydrogen such as polyethylene oxide is introduced, and a formalin condensate of benzene isocyanate.
The compounds described in JP-A-62-212190, JP-A-4-26189, JP-A-5-317694, and Japanese Patent Application No. 8-268721 are preferable.

The amount of the polyvalent isocyanate used is determined so that the average particle size of the microcapsules is 0.3 to 12 μm and the wall thickness is 0.01 to 0.3 μm. The dispersed particle diameter is generally about 0.2 to 10 μm.
In an emulsified dispersion in which an oil phase is added to an aqueous phase, a polyisocyanate polymerization reaction occurs at the interface between the oil phase and the aqueous phase to form a polyurea wall.

If a polyol and / or polyamine is further added to the hydrophobic solvent in the aqueous phase or the oil phase, it can react with the polyvalent isocyanate and be used as one of the components of the microcapsule wall. In the above reaction, it is preferable to keep the reaction temperature high or to add an appropriate polymerization catalyst from the viewpoint of increasing the reaction rate.
Specific examples of these polyols or polyamines include propylene glycol, glycerin, trimethylolpropane, triethanolamine, sorbitol, hexamethylenediamine and the like. When a polyol is added, a polyurethane wall is formed.
The polyisocyanate, polyol, reaction catalyst, polyamine for forming a part of the wall agent, etc. are well-known in the book (Keiji Iwata, Polyurethane Handbook, Nikkan Kogyo Shimbun (1987)).

  The emulsification can be carried out by appropriately selecting from known emulsifiers such as a homogenizer, a manton gorey, an ultrasonic disperser, a dissolver, and a kedy mill. After emulsification, the emulsion is heated to 30 to 70 ° C. in order to promote the capsule wall formation reaction. Further, during the reaction, in order to prevent aggregation between the capsules, it is necessary to add water to reduce the collision probability between the capsules or to perform sufficient stirring.

  Further, a dispersion for preventing aggregation may be added again during the reaction. As the polymerization reaction proceeds, the generation of carbon dioxide gas is observed, and its end can be regarded as the approximate end point of the capsule wall formation reaction. Usually, the target diazonium salt compound-containing microcapsules can be obtained by reacting for several hours.

  Next, the coupler used in the present invention can be used in the form of a solid dispersion by a sand mill or the like together with, for example, a water-soluble polymer, an organic base, and other color forming aids. Alternatively, after being dissolved in an insoluble high-boiling organic solvent, this is mixed with a polymer aqueous solution (aqueous phase) containing a surfactant and / or a water-soluble polymer as a protective colloid, and emulsified with a homogenizer or the like as an emulsified dispersion. It is preferable to use it. In this case, a low boiling point solvent can be used as a dissolution aid, if necessary. Further, the coupler and the organic base can be emulsified and dispersed separately, or mixed and then dissolved in a high boiling point organic solvent to be emulsified and dispersed. A preferable emulsified and dispersed particle size is 1 μm or less.

  The amount of the coupler used is preferably 0.1 to 30 parts by mass with respect to 1 part by mass of the diazonium salt compound.

  The high boiling point organic solvent used in this case can be appropriately selected from, for example, high boiling point oils described in JP-A-2-141279. Among these, from the viewpoint of emulsion stability of the emulsified dispersion, esters are preferable, and tricresyl phosphate is particularly preferable. The above oils can be used together with other oils.

  A low-boiling auxiliary solvent can also be added to the organic solvent as a dissolution aid. Examples of the auxiliary solvent include ethyl acetate, isopropyl acetate, butyl acetate, and methylene chloride. Depending on the case, it is possible to use only a low-boiling point auxiliary solvent without containing a high-boiling point oil.

  The water-soluble polymer to be contained as a protective colloid in the aqueous phase can be appropriately selected from known anionic polymers, nonionic polymers, and amphoteric polymers. Among them, for example, polyvinyl alcohol, Gelatin, cellulose derivatives and the like are preferable.

  Further, as the surfactant to be contained in the aqueous phase, an anionic or nonionic surfactant that does not cause precipitation or aggregation by acting on the protective colloid may be appropriately selected and used. it can. Examples of the surfactant include sodium alkylbenzene sulfonate, sodium alkyl sulfate, dioctyl sulfosuccinate sodium salt, polyalkylene glycol (for example, polyoxyethylene nonylphenyl ether), and the like.

(Basic substances, other)
In the present invention, it is also a preferred embodiment to add a basic substance such as an organic base for the purpose of promoting the coupling reaction between the diazonium salt compound and the coupler.
Examples of the organic base include tertiary amines, piperidines, piperazines, amidines, formamidines, pyridines, guanidines, morpholines, nitrogen-containing compounds, and the like. JP-A-46806, JP-A-62-20082, JP-A-57-169745, JP-A-60-94381, JP-A-57-123086, JP-A-60-49991, Preferred examples include those described in JP-B-2-24916, JP-B-2-28479, JP-A-60-165288, and JP-A-57-185430. These may be used alone or in combination of two or more.

  Among the above, specifically, N, N′-bis (3-phenoxy-2-hydroxypropyl) piperazine, N, N′-bis [3- (p-methylphenoxy) -2-hydroxypropyl] piperazine, N, N′-bis [3- (p-methoxyphenoxy) -2-hydroxypropyl] piperazine, N, N′-bis (3-phenylthio-2-hydroxypropyl) piperazine, N, N′-bis [3- (Β-naphthoxy) -2-hydroxypropyl] piperazine, N-3- (β-naphthoxy) -2-hydroxypropyl-N′-methylpiperazine, 1,4-bis {[3- (N-methylpiperazino) -2 Piperazines such as -hydroxy] propyloxy) benzene, N- [3- (β-naphthoxy) -2-hydroxy] propylmorpholine, 1,4-bis (3- Morpholines such as morpholino-2-hydroxy-propyloxy) benzene and 1,8-bis (3-morpholino-2-hydroxy-propyloxy) benzene, N- (3-phenoxy-2-hydroxypropyl) piperidine, N- Piperidines such as dodecylpiperidine and guanidines such as triphenylguanidine, tricyclohexylguanidine and dicyclohexylphenylguanidine are preferred.

  In the recording material of the present invention, for the purpose of accelerating the coupling reaction, the recording layer contains aminophenol, phenol, catechol, hydroquinone, amine, hydroxyamine, alcohol, thiol, sulfide. It is preferable to add a reducing agent such as alkali metal, alkaline earth metal, metal hydride, hydrazine, phenidone, aniline, phenyl ether, L-ascorbic acid, among them, hydroquinone, catechol, Aminophenol-based reducing agents are preferred. Of these, hydroquinone, catechol, and aminophenol are preferable.

  These reducing agents may be solid-dispersed in a fine particle state in the recording layer. When the diazo compound is microencapsulated, it can be added inside the microcapsule or both inside and outside.

  Moreover, it is preferable that it is 1-10 times mole with respect to a diazo compound, and, as for content of the said reducing agent, it is more preferable that it is 1-4 times mole. If the addition amount is less than 1 mol of the diazo compound content, the effect of improving the color developability and the effect of improving the image preservability may not be sufficiently obtained. The effect of improving the property may be reduced, and the raw preservation property may be deteriorated.

As the usage-amount of the said basic substance, 0.1-30 mass parts is preferable with respect to 1 mass part of diazonium salt compounds.
When the amount used is less than 0.1 parts by mass, a sufficient color density may not be obtained, and when it exceeds 30 parts by mass, decomposition of the diazonium salt compound may be promoted.

In addition to the above basic substances, a coloring aid can be added to the heat-sensitive recording layer for the purpose of accelerating the coloring reaction, that is, for rapid and complete thermal printing with low energy. Here, the coloring aid is a substance that increases the coloring density during heat recording or controls the coloring temperature, lowers the melting point of couplers, basic substances or diazonium salt compounds, and softens the capsule wall. This is for the purpose of making the diazonium salt compound, the basic substance, the coupler, etc. easy to react by the action that can lower the point.
Examples of the coloring aid include phenol derivatives, naphthol derivatives, alkoxy-substituted benzenes, alkoxy-substituted naphthalenes, aromatic ethers, thioethers, esters, amides, ureidos, urethanes, sulfonamide compounds, hydroxy compounds, and the like.

The coloring aid includes a heat-melting substance.
The heat-fusible substance is a substance that is solid at normal temperature and has a melting point of 50 ° C. to 150 ° C. that melts by heating, and is a substance that can dissolve a diazonium salt compound, a coupler, an organic base, or the like. Specific examples include carboxylic acid amides, N-substituted carboxylic acid amides, ketone compounds, urea compounds, and esters.

In the recording material of the present invention, for the purpose of improving fastness to light and heat of a thermochromic image or reducing yellowing due to light in an unprinted portion (non-image portion) after fixing, the following publicly known It is also preferable to use an antioxidant or the like.
Examples of the antioxidant include, for example, European Patent Publication No. 223739, Publication No. 309401, Publication No. 309402, Publication No. 310551, Publication No. 310552, Publication No. 457416, and German Patent No. 3435443, JP-A-54-48535, JP-A-62-262047, JP-A-63-113536, JP-A-63-163351, JP-A-2-262654, JP-A-2-71262. JP-A-3-121449, JP-A-5-61166, JP-A-5-119449, US Pat. No. 4,814,262, US Pat. No. 4,980,275, and the like.

It is also effective to use known various additives already used in heat-sensitive or pressure-sensitive recording materials.
Examples of the various additives include, for example, JP-A-60-107384, JP-A-60-107383, JP-A-60-125470, JP-A-60-125471, JP-A-60-125472, and JP-A-60-287485. No. 60-287486, No. 60-287487, No. 60-287488, No. 61-160287, No. 61-185483, No. 61-2111079, No. 62-146678. Gazette, 62-146680 gazette, 62-146679 gazette, 62-282858 gazette, 63-051174 gazette, 63-898877 gazette, 63-88380 gazette, 63-088381 gazette. 63-203372, 63-224989, 63-25128 No. 63-267594, No. 63-182484, JP-A-1-239282, No. 4-29185, No. 4-291684, No. 5-188687, No. 5-188686. And JP-A-5-110490, JP-A-5-170361, JP-B-48-043294, JP-A-48-033212, and the like.

  Specifically, 6-ethoxy-1-phenyl-2,2,4-trimethyl-1,2-dihydroquinoline, 6-ethoxy-1-octyl-2,2,4-trimethyl-1,2-dihydroquinoline 6-ethoxy-1-phenyl-2,2.4-trimethyl-1,2,3,4-tetrahydroquinoline, 6-ethoxy-1-octyl-2,2,4-trimethyl-1,2,3 4-tetrahydroquinoline, nickel cyclohexaneate, 2,2-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) -2-ethylhexane, 2-methyl-4-methoxy-diphenylamine, 1 -Methyl-2-phenylindole and the like.

  As addition amount of the said antioxidant or various additives, 0.05-100 mass parts is preferable with respect to 1 mass part of diazonium salt compounds, and 0.2-30 mass parts is more preferable.

  The antioxidant and various additives may be contained in a microcapsule together with a diazonium salt compound, or may be contained as a solid dispersion together with a coupler, a basic substance and other color forming aids, An emulsion may be contained together with a suitable emulsification aid, or may be contained in both forms. Moreover, antioxidant or various additives may be used independently and can also be used together. Furthermore, it can also be contained in the protective layer.

The antioxidant and various additives are not necessarily added to the same layer.
When a plurality of the antioxidants and / or various additives are used in combination, they are structurally classified as anilines, alkoxybenzenes, binderd phenols, hindered amines, hydroquinone derivatives, phosphorus compounds, sulfur compounds. In addition, different structures may be combined with each other, or a plurality of the same structures may be combined.

For the purpose of reducing yellowing of the background after image recording, a free radical generator (compound that generates free radicals upon light irradiation) used in a photopolymerizable composition or the like can be added.
Examples of the free radical generator include aromatic ketones, quinones, benzoin, benzoin ethers, azo compounds, organic disulfides, acyl oxime esters, and the like.
The addition amount of the free radical generator is preferably 0.01 to 5 parts by mass with respect to 1 part by mass of the diazonium salt compound.

Similarly, for the purpose of reducing yellow coloring, a polymerizable compound having an ethylenically unsaturated bond (hereinafter referred to as “vinyl monomer”) can also be used. A vinyl monomer is a compound having at least one ethylenically unsaturated bond (vinyl group, vinylidene group, etc.) in its chemical structure, and has a chemical form of monomer or prepolymer.
Examples of the vinyl monomer include unsaturated carboxylic acids and salts thereof, esters of unsaturated carboxylic acids and aliphatic polyhydric alcohols, amides of unsaturated carboxylic acids and aliphatic polyvalent amine compounds, and the like. The vinyl monomer is used in a proportion of 0.2 to 20 parts by mass with respect to 1 part by mass of the diazonium salt compound.
The free radical generator and the vinyl monomer can be used in a microcapsule together with a diazonium salt compound.

  Furthermore, citric acid, tartaric acid, oxalic acid, boric acid, phosphoric acid, pyrophosphoric acid and the like can be added as an acid stabilizer.

The heat-sensitive recording layer is prepared, for example, by preparing a coating solution containing a microcapsule containing a diazonium salt compound, a coupler, and a basic substance and other components as necessary, and applying the coating solution to paper, a synthetic resin film, etc. It can be coated by applying and drying on the support.
In the present invention, it is preferable that the thermosensitive recording layer contains a basic substance.

The coating can be appropriately selected from known coating methods, and examples thereof include bar coating, blade coating, air knife coating, gravure coating, roll coating coating, spray coating, dip coating, and curtain coating.
The coating, as a dry coating amount of the heat-sensitive recording layer after drying, 2.5~30g / m ² is preferred.

  The configuration of the heat-sensitive recording layer in the recording material of the present invention is not particularly limited. For example, it is an embodiment composed of a single layer in which microcapsules, couplers, basic substances, etc. are all contained in the same layer. Alternatively, it may be a multi-layer stacked type that is included in a separate layer. Alternatively, an intermediate layer described in JP-A-61-54980 or the like may be provided on a support, and then a heat-sensitive recording layer may be applied and formed. Each of these embodiments is a full-color coloring type embodiment in which a plurality of monochromatic and single thermosensitive recording layers having different hues are laminated.

In the recording material of the present invention, each layer such as a heat-sensitive recording layer, an intermediate layer or a protective layer described later can contain a binder, and examples of the binder include known water-soluble polymer compounds and latexes. It can be selected appropriately.
Examples of the water-soluble polymer compound include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, starch derivatives, casein, gum arabic, gelatin, ethylene-maleic anhydride copolymer, styrene-maleic anhydride copolymer. , Polyvinyl alcohol, silanol-modified polyvinyl alcohol, carboxy-modified polyvinyl alcohol, epichlorohydrin-modified polyamide, isobutylene-maleic salicylic anhydride copolymer, polyacrylic acid, polyacrylic acid amide and the like, and modified products thereof.

Examples of the latex include styrene-butadiene rubber latex, methyl acrylate-butadiene rubber latex, and vinyl acetate emulsion.
Of these, hydroxyethyl cellulose, starch derivatives, gelatin, polyvinyl alcohol derivatives, polyacrylic acid amide derivatives and the like are preferable.

  In addition, the recording material of the present invention may contain a pigment, and examples of the pigment include organic and inorganic materials such as kaolin, calcined kaolin, talc, wax, diatomaceous earth, Calcium carbonate, aluminum hydroxide, magnesium hydroxide, zinc oxide, lithopone, amorphous silica, colloidal silica, calcined stone, silica, magnesium carbonate, titanium oxide, alumina, barium carbonate, barium sulfate, mica, microballoon, urea -Formalin filler, polyester particle, cellulose filler and the like.

  In addition, various additives such as known waxes, antistatic agents, antifoaming agents, conductive agents, fluorescent dyes, surfactants, ultraviolet absorbers and their precursors can be used as necessary.

In the recording material of the present invention, a protective layer may be provided on the thermosensitive recording layer as necessary. Two or more protective layers may be laminated as necessary.
Materials used for the protective layer include polyvinyl alcohol, carboxy-modified polyvinyl alcohol, vinyl acetate-acrylamide copolymer, silicon-modified polyvinyl alcohol, starch, modified starch, methylcellulose, carboxymethylcellulose, hydroxymethylcellulose, gelatins, gum arabic, and casein , Styrene-maleic acid copolymer hydrolyzate, styrene-maleic acid copolymer half ester hydrolyzate, isobutylene-maleic anhydride copolymer hydrolyzate, polyacrylamide derivative, polyvinylpyrrolidone, polystyrene sulfonate soda, alginic acid Water-soluble polymer compounds such as soda, styrene-butadiene rubber latex, acrylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex , Latexes such as vinyl acetate emulsion.

  The water-soluble polymer compound can be further improved in storage stability by crosslinking. The crosslinking agent can be appropriately selected from known crosslinking agents, and examples thereof include water-soluble initial condensates such as N-methylol urea, N-methylol melamine, urea-formalin; dioxal, glutaraldehyde and the like. Aldehyde compounds; inorganic crosslinking agents such as boric acid and borax; polyamide epichlorohydrin and the like.

For the protective layer, known pigments, metal soaps, waxes, surfactants and the like can also be used. The fluorescent brightener precursor may be contained in a protective layer.
The coating amount of the protective layer is preferably 0.2 to 5 g / m ^{2 and} more preferably 0.5 to ² g / m ^{2 in} terms of dry coating amount. The film thickness is preferably 0.2-5 μm, more preferably 0.5-2 μm.
Moreover, when providing a protective layer, you may contain a well-known ultraviolet absorber and its precursor in this protective layer.
The protective layer can be provided by the above-described known coating method as in the case of forming the heat-sensitive recording layer on the support.

  As the support that can be used for the recording material of the present invention, any of the paper supports used for ordinary pressure-sensitive paper, heat-sensitive paper, dry or wet diazo copy paper, etc. can be used. Paper, coated paper, plastic film laminated paper, synthetic paper, and plastic films such as polyethylene terephthalate and polyethylene naphthalate can be used.

On the support, a back coat layer may be provided for the purpose of correcting the curl balance or improving the chemical resistance from the back surface. The back coat layer can be provided in the same manner as the protective layer.
Further, if necessary, an antihalation layer is provided between the support and the heat-sensitive recording layer or on the surface of the support on the side where the heat-sensitive recording layer is provided, and a slip layer or an antistatic layer is provided on the back surface. An adhesive layer or the like can also be provided.
Also, a label may be formed by combining release paper with an adhesive layer on the back surface of the support (the surface on which the thermosensitive recording layer is not provided).

  By encapsulating the diazonium salt compound in microcapsules, the long-term stability as a recording material can be further enhanced.

The recording layer of the recording material of the present invention may contain an electron donating dye precursor and an electron accepting compound. Further, the electron donating dye precursor is preferably encapsulated in a microcapsule like the diazonium salt compound.
The electron donating dye precursor and the electron accepting compound are disclosed in JP-A-6-328860, JP-A-7-290826, JP-A-7-314904, JP-A-8-324116, and JP-A-3-3. JP-A-37727, JP-A-9-31345, JP-A-9-111136, JP-A-9-118073, JP-A-11-157221, and the like. Specific examples are shown below, but the present invention is not limited thereto.

-Specific examples of electron accepting compounds-
Examples of the electron-accepting compound include phenol derivatives, salicylic acid derivatives, and hydroxybenzoic acid esters. In particular, bisphenols and hydroxybenzoic acid esters are preferable. Some examples of these are 2,2-bis (p-hydroxyphenyl) propane (ie, bisphenol A), 4,4 ′-(p-phenylenediisopropylidene) diphenol (ie, bisphenol P), 2,2-bis (p-hydroxyphenyl) pentane, 2,2-bis (p-hydroxyphenyl) ethane, 2,2-bis (p-hydroxyphenyl) butane, 2,2-bis (4′-hydroxy-) 3 ', 5'-dichlorophenyl) propane, 1,1- (p-hydroxyphenyl) cyclohexane, 1,1- (p-hydroxyphenyl) propane, 1,1- (p-hydroxyphenyl) pentane, 1,1- (P-hydroxyphenyl) -2-ethylhexane, 3,5-di (α-methylbenzyl) salicylic acid and its polyvalent metal salt, 3,5-di (te t-butyl) salicylic acid and its polyvalent metal salt, 3-α, α-dimethylbenzylsalicylic acid and its polyvalent metal salt, butyl p-hydroxybenzoate, benzyl p-hydroxybenzoate, p-hydroxybenzoic acid-2- Examples include ethylhexyl, p-phenylphenol, and p-cumylphenol.

(Recording method)
The recording method of the present invention includes a step of recording an image on a recording layer, and a step of heating the recording material entirely before or after image recording to generate a fluorescent brightener from the fluorescent brightener precursor.
The image recording process will be described by taking as an example a heat-sensitive recording material provided with a heat-sensitive recording layer containing a diazonium salt compound as a recording layer. By image-wise heat-printing, the capsule wall containing polyurea and / or polyurethane in the layer becomes soft and becomes material permeable in the heating part of the heat-sensitive recording layer, and couplers and basic substances (organic bases) outside the capsule become soft. ) Enters the microcapsule, the image may be colored to form an image. In this case, after color development, by further irradiating light corresponding to the absorption wavelength of the diazonium salt compound (photofixing), the diazonium salt compound undergoes a decomposition reaction and loses reactivity with the coupler, thereby fixing the image. Can do. By carrying out photofixing as described above, the unreacted diazonium salt compound loses its activity by causing a decomposition reaction, and therefore, due to density fluctuations in the formed image and the occurrence of stain in the non-image area (background area) Coloring, that is, a decrease in whiteness and a decrease in image contrast accompanying the decrease can be suppressed.

Examples of the light source used for the light fixing include various light-emitting diodes, fluorescent lamps, xenon lamps, mercury lamps, and the like, and the emission spectrum of these light sources substantially matches the absorption spectrum of the diazonium salt compound in the heat-sensitive recording material. Is preferable in that it can be fixed with high efficiency. In addition, a light emitting diode is preferable from the viewpoint of the temporal stability of light fixing.
In particular, in the present invention, it is particularly preferable to use a light source having a light emission center wavelength of 340 to 385 nm.

  Further, it can also be used as a light-writing heat-developable heat-sensitive recording material in which image-like writing is performed with light and heat development is performed to form an image. In this case, the printing process is performed by a light source such as a laser instead of the heating device as described above.

In the recording material of the present invention, the recording process in the multicolor thermosensitive recording material provided with a plurality of thermosensitive recording layers that develop colors different from each other can be performed, for example, as follows. The following is a second thermosensitive recording layer containing a first thermosensitive recording layer (A layer) containing an electron donating dye precursor and an electron accepting compound on a support, and a diazonium salt compound having a maximum absorption wavelength of 365 ± 30 nm. A multicolor thermosensitive recording material having a recording layer (B layer) and a third thermosensitive recording layer (C layer) containing a diazonium salt compound having a maximum absorption wavelength of 445 ± 50 nm.
First, the third heat-sensitive recording layer (C layer) is heated, and the diazonium salt compound contained in the layer reacts with the coupler to develop a color. Next, irradiation with 365 ± 30 nm light is performed to decompose the unreacted diazonium salt compound contained in the third thermosensitive recording layer (C layer). Next, sufficient heat is applied to the second heat-sensitive recording layer (B layer) to develop a color, and the diazonium salt compound contained in the layer reacts with the coupler compound to develop a color. At this time, the third heat-sensitive recording layer (C layer) is also strongly heated at the same time. However, since the diazonium salt compound has already been decomposed and the coloring ability is lost, no color is developed. Thereafter, the diazonium salt compound contained in the second thermosensitive recording layer (B layer) is decomposed by irradiation with light of 445 ± 50 nm. Finally, the first heat-sensitive recording layer (A layer) is colored by applying sufficient heat. At this time, the first and second heat-sensitive recording layers are also strongly heated at the same time, but the diazonium salt compound has already been decomposed and does not develop color because the coloring ability is lost.

Next, in the recording method of the present invention, the step of heating the recording material over the entire surface in order to cause the fluorescent brightener generation reaction will be described.
The heating energy applied to the entire surface of the recording material in order to cause the fluorescent whitening agent generation reaction to be performed is equal to or higher than the thermal energy necessary for the fluorescent whitening agent generation reaction in each of the above reaction formulas. As this thermal energy, 50 to 200 mJ / m ² is preferable, and 75 to 150 mJ / m ² is more preferable. The heating energy preferably takes into account the type of color developing component contained in the recording layer. For example, when the recording material has a heat-sensitive recording layer (one layer or two or more layers) containing a diazonium salt compound, fixing is performed after recording. However, it is preferable that the reaction for generating a fluorescent brightener occurs after fixing. (Fixing light is not absorbed by the fluorescent whitening agent at the time of fixing), and the thermal energy (and heating energy) necessary for the fluorescent whitening agent generation reaction is determined from the recording energy of the one or more heat-sensitive recording layers. It is preferable that it is larger.
On the other hand, when the recording material has a heat-sensitive recording layer containing a leuco coloring component, it is necessary to make the thermal energy and heating energy smaller than the recording energy.

When the multi-color heat-sensitive recording material, for example, the three heat-sensitive recording layers provided on the support all contain a diazonium salt compound as the color forming component, the thermal energy and heating energy may be made larger than the recording energy of the three layers. preferable.
In the case of a multicolor thermosensitive recording material in which a thermosensitive recording layer containing a leuco coloring component is provided on the side closest to the support and a diazo thermosensitive recording layer containing two layers of a diazonium salt compound is provided thereon, 2 It is preferable to make the thermal energy and heating energy larger than each recording energy of the diazo thermal recording layer of the layer, while it is necessary to make the thermal energy and heating energy smaller than the recording energy of the thermal recording layer closest to the support It is.

In order to increase the whiteness of the recording material, it is necessary to heat the entire surface of the recording material to generate the fluorescent whitening agent generation reaction as described above.
When the recording material is a heat-sensitive recording material and the heat-sensitive recording layer contains a leuco coloring component, the entire surface heating may be performed before or after the heat-sensitive recording, but the recording energy and the heat energy and The relationship with the heating energy needs to be set as described above. When the heat-sensitive recording layer contains a diazonium salt compound as a color forming component, it is preferable to heat the entire surface after recording and fixing of the heat-sensitive recording layer.
In a multicolor thermosensitive recording material, for example, a multicolor thermosensitive recording material in which all of the three thermosensitive recording layers provided on the support as described above contain a diazonium salt compound as a coloring component, the entire heating of the recording material is performed in three layers. It is preferable to carry out after recording and fixing. In the case of a multicolor thermosensitive recording material in which a thermosensitive recording layer containing a leuco coloring component is provided on the side closest to the support, and a diazo thermosensitive recording layer containing two layers of a diazonium salt compound is provided thereon. It is preferable to heat the entire surface after recording and fixing of the two diazo thermosensitive recording layers and before or after recording of the remaining one thermosensitive recording layer.
The whole surface heating may be performed by a thermal head or a heat roller.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to this. In the following description, “part” means “part by mass” and “%” means “% by mass” unless otherwise specified.

(Example 1)
<Preparation of phthalated gelatin solution>
Phthalated gelatin (trade name: MGP gelatin, manufactured by Nippi Collagen Co., Ltd.) 32 parts, 1,2-benzothiazolin-3-one (3.5% methanol solution, manufactured by Daito Chemical Industry Co., Ltd.) 0.9143 Part and 367.1 parts of ion-exchanged water were mixed and dissolved at 40 ° C. to obtain a phthalated gelatin aqueous solution.

<Preparation of alkali-treated gelatin solution>
25.5 parts of alkali-treated low ion gelatin (trade name; # 750 gelatin, manufactured by Nitta Gelatin Co., Ltd.), 1,2-benzothiazolin-3-one (3.5% methanol solution, Daito Chemical Industry Co., Ltd.) )) 0.7286 parts, calcium hydroxide 0.153 parts, and ion-exchanged water 143.6 parts were mixed and dissolved at 50 ° C. to obtain an aqueous gelatin solution for preparing an emulsion.

(1) Preparation of yellow thermosensitive recording layer solution <Preparation of diazonium salt compound-encapsulated microcapsule solution (a)>
To 16.1 parts of ethyl acetate, 4.4 parts of the following diazonium compound (A), 4.8 parts of isopropyl biphenyl, 4.8 parts of diphenyl phthalate, and diphenyl- (2,4,6-trimethylbenzoyl) phosphine oxide ( 0.4 part of a trade name: Lucillin TPO, manufactured by BASF Japan Ltd.) was added and heated to 40 ° C. to dissolve uniformly. Mixture of xylylene diisocyanate / trimethylolpropane adduct and xylylene diisocyanate / bisphenol A adduct as a capsule wall material in the above mixture (trade name; Takenate D119N (50% ethyl acetate solution), Takeda Pharmaceutical Co., Ltd.) 8.6 parts was added and stirred uniformly to obtain a mixed liquid (I).
Separately, 16.3 parts of ion-exchanged water and 0.34 part of Scratch AG-8 (50%) manufactured by Nippon Seika Co., Ltd.) were added to 58.6 parts of the phthalated gelatin aqueous solution to obtain a mixed liquid (II). It was.
The mixed solution (I) was added to the mixed solution (II), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho). After adding 20 parts of water to the obtained emulsion and homogenizing it, the mixture was stirred at 40 ° C. to carry out an encapsulation reaction for 3 hours while removing ethyl acetate. Thereafter, 4.1 parts of ion exchange resin Amberlite IRA68 (manufactured by Organo Corp.) and 8.2 parts of Amberlite IRC50 (manufactured by Organo Corp.) were added and further stirred for 1 hour. Thereafter, the ion exchange resin was removed by filtration, and the concentration was adjusted so that the solid content concentration of the capsule liquid was 20.0% to obtain a diazonium salt compound-encapsulating microcapsule liquid (a). The obtained microcapsules had a median diameter of 0.36 μm as a result of particle size measurement (LA-700, manufactured by Horiba, Ltd.).

<Preparation of coupler compound emulsion (a)>
To 33.0 parts of ethyl acetate, 9.9 parts of the following coupler compound (C), 9.9 parts of triphenylguanidine (manufactured by Hodogaya Chemical Co., Ltd.), 4,4 ′-(m-phenylenediisopropylidene) diphenol ( Product name; 20.8 parts of bisphenol M (Mitsui Petrochemical Co., Ltd.)), 3.4 parts of Compound 1-1, 4- (2-ethylhexyloxy) benzenesulfonic acid amide (manac Co., Ltd.) 6 parts, 6.8 parts of 4-n-pentyloxybenzenesulfonic acid amide (manac Co., Ltd.), calcium dodecylbenzenesulfonate (trade name Piionin A-41-C 70% methanol solution, manufactured by Takemoto Yushi Co., Ltd.) ) 4.2 parts were dissolved to obtain a mixed liquid (III).
Separately, 107.3 parts of ion-exchanged water was mixed with 206.3 parts of the alkali-treated gelatin aqueous solution to obtain a mixed liquid (IV).
The mixed solution (III) was added to the mixed solution (IV), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). The obtained coupler compound emulsion was heated under reduced pressure to remove ethyl acetate, and then the concentration was adjusted so that the solid content concentration was 26.5%. The resulting coupler compound emulsion had a median diameter of 0.21 μm as a result of particle size measurement (LA-700, manufactured by Horiba, Ltd.).
Further, 9 parts of SBR latex (trade name: SN-307, 48% solution, manufactured by Sumika Aves Latex Co., Ltd.) adjusted to 26.5% are added to 100 parts of the above coupler compound emulsion. The mixture was stirred uniformly to obtain a coupler compound emulsion (a).

<Preparation of coating liquid (a)>
The diazonium salt compound-encapsulated microcapsule liquid (a) and the coupler compound-emulsified liquid (a) are mixed so that the mass ratio of the encapsulated coupler compound / diazo compound is 2.2 / 1, and thermal recording is performed. A layer coating solution (a) was obtained.

(2) Preparation of magenta thermosensitive recording layer solution <Preparation of diazonium salt compound-encapsulated microcapsule solution (b)>
15.1 parts of ethyl acetate, 2.8 parts of the following diazonium compound (D) (maximum absorption wavelength 365 nm), 3.8 parts of diphenyl phthalate, 3.9 parts of phenyl 2-benzoyloxybenzoate, and trimethylolpropane trimethacrylate (Trade name; light ester TMP, manufactured by Kyoei Yushi Chemical Co., Ltd.) 4.2 parts and calcium dodecylbenzenesulfonate (trade name: Pionein A-41-C 70% methanol solution, manufactured by Takemoto Yushi Co., Ltd.) 0.1 Part was added and heated to dissolve uniformly. Mixture of xylylene diisocyanate / trimethylolpropane adduct and xylylene diisocyanate / bisphenol A adduct as a capsule wall material in the above mixture (trade name: Takenate D119N (50% ethyl acetate solution), manufactured by Takeda Pharmaceutical Co., Ltd.) 2.5 parts and 6.8 parts of xylylene diisocyanate / trimethylolpropane adduct (trade name: Takenate D110N (75% ethyl acetate solution), Takeda Pharmaceutical Co., Ltd.) are added, and the mixture is stirred uniformly. (V) was obtained.
Separately, 21.0 parts of ion-exchanged water was added to and mixed with 55.3 parts of the phthalated gelatin aqueous solution to obtain a mixed liquid (VI).
The mixed solution (V) was added to the mixed solution (VI), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho). After 24 parts of water was added to the obtained emulsion and homogenized, the mixture was stirred at 40 ° C. to carry out an encapsulation reaction for 3 hours while removing ethyl acetate. Thereafter, 4.1 parts of ion exchange resin Amberlite IRA68 (manufactured by Organo Corp.) and 8.2 parts of Amberlite IRC50 (manufactured by Organo Corp.) were added and further stirred for 1 hour. Thereafter, the ion exchange resin was removed by filtration, and the concentration was adjusted so that the solid content concentration of the capsule liquid was 20.0% to obtain a diazonium salt compound-encapsulating microcapsule liquid (a). The obtained microcapsules had a median diameter of 0.43 μm as a result of particle size measurement (LA-700, carried out by Horiba, Ltd.).

<Preparation of coupler compound emulsion (b)>
36.9 parts of ethyl acetate, 11.9 parts of the following coupler compound (F), 14.0 parts of triphenylguanidine (manufactured by Hodogaya Chemical Co., Ltd.), 4,4 '-(m-phenylenediisopropylidene) diphenol ( Trade name: Bisphenol M (Mitsui Petrochemical Co., Ltd.) 14.0 parts, 1,1- (p-hydroxyphenyl) -2-ethylhexane 14 parts, tricresyl phosphate 1.7 parts, diethyl maleate 0 8 parts, calcium dodecylbenzenesulfonate (trade name: Piionin A-41-C 70% methanol solution, manufactured by Takemoto Yushi Co., Ltd.) 4.5 parts were dissolved to obtain a mixed solution (VII).
Separately, 107.3 parts of ion-exchanged water was mixed with 206.3 parts of an alkali-treated gelatin aqueous solution to obtain a mixed liquid (VIII).
The mixed solution (VII) was added to the mixed solution (VIII), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). The obtained coupler compound emulsion was heated under reduced pressure to remove ethyl acetate, and then the concentration was adjusted so that the solid content concentration was 24.5% to obtain a coupler compound emulsion (b). The resulting coupler compound emulsion had a median diameter of 0.22 μm as a result of particle size measurement (LA-700, manufactured by Horiba, Ltd.).

<Preparation of coating liquid (b)>
The diazonium salt compound-encapsulated microcapsule liquid (a) and the coupler compound-emulsified liquid (b) were mixed so that the mass ratio of the encapsulated coupler compound / diazo compound was 3.5 / 1. Further, an aqueous solution (5%) of polystyrene sulfonic acid (partially potassium hydroxide neutralized) was mixed so as to be 0.2 parts with respect to 10 parts of the capsule liquid, and the coating liquid for thermal recording layer (b) was prepared. Obtained.

(3) Preparation of cyan thermosensitive recording layer solution <Preparation of electron-donating dye precursor-encapsulated microcapsule solution (c)>
A mixture of 7.6 parts of the following electron donating dye (H), 1-methylpropylphenyl-phenylmethane and 1- (1-methylpropylphenyl) -2-phenylethane (trade name) Hysol SAS-310, manufactured by Nippon Oil Co., Ltd. (8.0 parts) and the following compound (I) (trade name; trade name of Irgaperm 2140 Ciba Geigy Co., Ltd.) were added and heated to dissolve uniformly. . 7.2 parts of xylylene diisocyanate / trimethylolpropane adduct (trade name; Takenate D110N (75% ethyl acetate solution), Takeda Pharmaceutical Co., Ltd.) and polymethylene polyphenyl polyisocyanate as capsule wall material in the above mixture (Product name: Millionate MR-200, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added in an amount of 5.3 parts and stirred uniformly to obtain a mixed solution (IX).
Separately, 28.8 parts of the aqueous phthalated gelatin solution, 9.5 parts of ion-exchanged water, 0.17 part of Scraph AG-8 (50%) manufactured by Nippon Seika Co., Ltd., and sodium dodecylbenzenesulfonate (10% aqueous solution) ) 4.3 parts were added and mixed to obtain a mixed solution (X).
The mixed solution (IX) was added to the mixed solution (X), and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). 50 parts of water and 0.12 part of ethyltriamine were added to the resulting emulsion to homogenize, and the mixture was stirred at 65 ° C. for 3 hours while removing ethyl acetate, so that the solid concentration of the capsule liquid was 33%. The concentration was adjusted to obtain a microcapsule solution. The obtained microcapsules had a median diameter of 1.00 μm as a result of particle size measurement (LA-700, manufactured by Horiba, Ltd.).
Furthermore, to 100 parts of the above microcapsule solution, 3.7 parts of a 25% aqueous solution of sodium dodecylbenzenesulfonate (trade name; Neoperex F-25, manufactured by Kao Corporation) was added and stirred uniformly to make microcapsules A dispersion (c) was obtained.

<Preparation of electron-accepting compound dispersion (c)>
11.3 parts of the phthalated gelatin aqueous solution, 30.1 parts of ion-exchanged water, 15 parts of 4,4 ′-(p-phenylenediisopropylidene) diphenol (trade name; bisphenol P, manufactured by Mitsui Petrochemical Co., Ltd.) 3.8 parts of 2% -2-ethylhexyl sodium succinate aqueous solution was added and dispersed overnight with a ball mill to obtain a dispersion. The solid content concentration of this dispersion was 26.6%.
After adding 45.2 parts of the alkali-treated gelatin aqueous solution to 100 parts of the above dispersion and stirring for 30 minutes, ion-exchanged water was added so that the solid content concentration of the dispersion was 23.5% to obtain an electron-accepting compound. A dispersion (c) was obtained.

(Preparation of liquid containing brightening agent precursor)
<Preparation of fluorescent whitening agent precursor (FC compound) encapsulated microcapsule solution>
18.1 parts of ethyl acetate and 4.1 parts of the exemplified FC compound (FC-1), a mixture of 1-methylpropylphenyl-phenylmethane and 1- (1-methylpropylphenyl) -2-phenylethane Name: 8.0 parts of Hysol SAS-310 (manufactured by Nippon Oil Co., Ltd.) was added and heated to dissolve uniformly. 10.5 parts of xylylene diisocyanate / trimethylolpropane adduct (trade name: Takenate D110N (75% ethyl acetate solution), Takeda Pharmaceutical Co., Ltd.) and polymethylene polyphenyl polyisocyanate as capsule wall material in the above mixture (Product name: Millionate MR-200, manufactured by Nippon Polyurethane Industry Co., Ltd.) was added in an amount of 7.6 parts, and the mixture was stirred uniformly to obtain a mixed liquid (oil phase).
Separately, 28.8 parts of the aqueous phthalated gelatin solution, 9.5 parts of ion-exchanged water, 0.17 part of Scraph AG-8 (50%) manufactured by Nippon Seika Co., Ltd., and sodium dodecylbenzenesulfonate (10% aqueous solution) ) 4.3 parts were added and mixed to obtain a mixed solution (aqueous phase).
The aqueous phase was added to the oil phase, and the mixture was emulsified and dispersed at 40 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). 50 parts of water and 0.12 part of ethyltriamine were added to the resulting emulsion and homogenized. The mixture was stirred at 65 ° C. for 3 hours while removing ethyl acetate, and the solid content concentration of the capsule liquid was 25%. The concentration was adjusted to obtain a microcapsule solution. The obtained microcapsules had a median diameter of 0.81 μm as a result of particle size measurement (LA-700, carried out by Horiba, Ltd.).

<Preparation of optical brightener precursor (FD compound) dispersion>
A ball mill is prepared by adding 30.1 parts of ion-exchanged water, 15 parts of the exemplified FD compound (FD-8) and 3.8 parts of a 2-ethylhexyl sodium succinate aqueous solution (2%) to 11.3 parts of the phthalated gelatin aqueous solution. Was dispersed overnight to obtain a dispersion. After adding 45.2 parts of the alkali-treated gelatin aqueous solution to 100 parts of this dispersion and stirring for 30 minutes, ion-exchanged water was added so that the solids concentration of the dispersion was 23.5%, and the fluorescent brightening agent was added. A precursor (FD compound) dispersion was obtained.

<Preparation of liquid containing brightening agent precursor>
The optical brightener precursor (FC compound) -encapsulating microcapsule liquid and the optical brightener precursor (FD compound) dispersion are mixed so that the mass ratio is 2: 1, and the optical brightener precursor is contained. Liquid.

<Preparation of coating liquid (c)>
The electron-donating dye precursor-encapsulated microcapsule liquid (c), the electron-accepting compound dispersion liquid (c), and the fluorescent brightener precursor-containing liquid were mixed to obtain a coating liquid (c). The compounding ratio (mass) of the microcapsule liquid (c) and the dispersion liquid (c) is such that the electron-accepting compound / electron-donating dye precursor is 10/1 (mass). The addition amount of the agent precursor-containing liquid was such that the coating amount of the solid content in the cyan thermosensitive recording layer was 0.19 g / m ² .

<Preparation of coating solution for intermediate layer>
100.0 parts of alkali-treated low ion gelatin (trade name; # 750 gelatin, manufactured by Nitta Gelatin Co., Ltd.), 1,2-benzothiazolin-3-one (3.5% methanol solution, Daito Chemical Industries, Ltd.) )) 2.857 parts, 0.5 parts of calcium hydroxide and 521.643 parts of ion-exchanged water were mixed and dissolved at 50 ° C. to obtain an aqueous gelatin solution for forming an intermediate layer.
10.0 parts gelatin aqueous solution for intermediate layer preparation, 0.05 parts sodium (4-nonylphenoxytrioxyethylene) butyl sulfonate (2.0% aqueous solution manufactured by Sankyo Chemical Co., Ltd.), boric acid (4.0%) 1.5 part aqueous solution, 0.19 part polystyrene sulfonic acid (partially potassium hydroxide neutralized) aqueous solution (5%), 4% aqueous solution of the following compound (J) (manufactured by Wako Pure Chemical Industries, Ltd.) 42 parts, 1.13 parts of a 4% aqueous solution of the following compound (J ′) and 0.67 parts of ion-exchanged water were mixed to obtain a coating solution for an intermediate layer.

<Preparation of coating solution for light transmittance adjusting layer>
(Iii-1) Preparation of UV absorber precursor microcapsule solution [2-Allyl-6- (2H-benzotriazol-2-yl) -4-t-octylphenyl] as an UV absorber precursor in 71 parts of ethyl acetate ] 4.5 parts of benzenesulfonate, 1.0 part of 2,2′-t-octylhydroquinone, 3.8 parts of tricresyl phosphate, α-methylstyrene dimer (trade name: MSD-100, manufactured by Mitsui Chemicals, Inc.) 5.7 parts, calcium dodecylbenzenesulfonate (trade name: Piionin A-41-C (70% methanol solution), manufactured by Takemoto Yushi Co., Ltd.) 0.45 parts were dissolved and dissolved uniformly. Add 54.7 parts of xylylene diisocyanate / trimethylolpropane adduct (trade name; Takenate D110N (75% ethyl acetate solution), Takeda Pharmaceutical Co., Ltd.) as a capsule wall material to the above mixture and stir uniformly. An ultraviolet absorber precursor mixed solution (VII) was obtained.
Separately, 8.9 parts of 30% phosphoric acid aqueous solution and 532.6 parts of ion-exchanged water were mixed with 52 parts of itaconic acid-modified polyvinyl alcohol (trade name: KL-318, manufactured by Kuraray Co., Ltd.), and ultraviolet absorber precursor micro A PVA aqueous solution for capsule liquid was prepared.
The ultraviolet absorbent precursor mixed liquid (VII) is added to 516.06 parts of the PVA aqueous solution for the ultraviolet absorbent precursor microcapsule liquid, and the mixture is used at 20 ° C. using a homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd.). Emulsified and dispersed. After adding 254.1 parts of ion-exchanged water to the obtained emulsion and homogenizing it, an encapsulation reaction was carried out for 3 hours with stirring at 40 ° C. Thereafter, 94.3 parts of ion exchange resin Amberlite MB-3 (manufactured by Organo Corporation) was added, and the mixture was further stirred for 1 hour. Thereafter, the ion exchange resin was removed by filtration, and the concentration was adjusted so that the solid concentration of the capsule liquid was 13.5%. The obtained microcapsules had a median diameter of 0.23 ± 0.05 μm as a result of particle size measurement (LA-700, manufactured by Horiba, Ltd.). To this capsule solution 859.1 parts, carboxy-modified styrene butadiene latex (trade name: SN-307, (48% aqueous solution), manufactured by Sumitomo Nougatac Co., Ltd.) 2.416 parts and ion-exchanged water 39.5 parts were mixed. An ultraviolet absorber precursor microcapsule solution was obtained.
(Iii-2) Preparation of coating liquid for light transmittance adjusting layer 1000 parts of the above-mentioned UV absorber precursor microcapsule liquid, fluorine-based surfactant (trade name: Megafac F-120, 5% aqueous solution, Dainippon Ink and Chemicals, Inc. Industrial Co., Ltd.) 5.2 parts, 4.75 parts of 4% aqueous sodium hydroxide, sodium (4-nonylphenoxytrioxyethylene) butyl sulfonate (2.0% aqueous solution manufactured by Sankyo Chemical Co., Ltd.) 39 parts were mixed to obtain a coating solution for light transmittance adjusting layer.

<Preparation of coating solution for protective layer>
(Iv-1) Preparation of polyvinyl alcohol solution for protective layer 160 parts of vinyl alcohol-alkyl vinyl ether copolymer (trade name: EP-130, manufactured by Denki Kagaku Kogyo Co., Ltd.), sodium alkyl sulfonate and polyoxyethylene alkyl ether A mixture of phosphate ester (trade name: Neoscore CM-57, (54% aqueous solution), manufactured by Toho Chemical Industry Co., Ltd.) 8.74 parts and ion-exchanged water 3832 parts are mixed and heated at 90 ° C. for 1 hour. A uniform polyvinyl alcohol solution for protective layer was obtained by dissolution.
(Iv-2) Preparation of pigment dispersion for protective layer Barium sulfate (trade name: BF-21F, barium sulfate content 93% or more, manufactured by Sakai Chemical Industry Co., Ltd.) 8 parts anionic special polycarboxylic acid type Polymer protective agent (trade name: Poise 532A (40% aqueous solution), manufactured by Kao Corporation) 0.2 part, 11.8 parts of ion-exchanged water are mixed and dispersed in a dynomill to produce a pigment dispersion for protective layer It was created. As a result of particle size measurement (LA-910, manufactured by HORIBA, Ltd.), this dispersion was found to have a median diameter of 0.15 μm or less.
To 45.6 parts of the above barium sulfate dispersion, 8.1 parts of colloidal silica (trade name: Snowtex O (20% aqueous dispersion), manufactured by Nissan Chemical Co., Ltd.) is added to obtain the desired dispersion. It was.

(Iv-3) Preparation of Matting Agent Dispersion for Protective Layer An aqueous dispersion of 1,2-benzisothiazolin-3-one in 180 parts of wheat starch (trade name: Wheat Starch S, manufactured by Shinshin Food Industry Co., Ltd.) (Trade name: PROXEL BD, manufactured by IC Corporation) 3.81 parts and 1976.19 parts of ion-exchanged water were mixed and dispersed uniformly to obtain a matting agent dispersion for protective layer.
(Iv-4) Preparation of Coating Blend Solution for Protective Layer Fluorosurfactant (trade name: Megafac F-120, 5% aqueous solution, Dainippon Ink & Chemicals, Inc.) was added to 1000 parts of the polyvinyl alcohol solution for protective layer. ) 40 parts, 50 parts of (4-nonylphenoxytrioxyethylene) butyl sulfonate (manufactured by Sankyo Chemical Co., Ltd., 2.0% aqueous solution), 49.87 parts of the pigment dispersion for protective layer, the protective layer 16.65 parts of matting agent dispersion, 48.7 parts of zinc stearate dispersion (trade name: Hydrin F115, 20.5% aqueous solution, manufactured by Chukyo Yushi Co., Ltd.) and 280 parts of ion-exchanged water are uniformly mixed. A coating blend liquid for protective layer was obtained.

<Application of coating solution for each thermosensitive recording layer>
From above, the thermal recording layer coating solution (c), the intermediate layer coating solution, the thermal recording layer coating solution (b), and the intermediate layer are formed on a photographic paper support laminated with polyethylene on fine paper. 7 layers of coating liquid, heat-sensitive recording layer coating liquid (a), light transmittance adjusting layer coating liquid, and protective layer coating liquid were successively applied in the order of 30 ° C. humidity 30% and 40 ° C. humidity. Each was dried under the condition of 30% to obtain a multicolor thermosensitive recording material.
At this time, the heat sensitive recording layer coating solution (a) was applied in the same manner so that the coating amount of the diazo compound (A) contained in the solution was 0.150 g / m ^{2 in} terms of solid content. Similarly, the coating amount of the recording layer coating liquid (b) is such that the coating amount of the diazo compound (D) contained in the liquid is 0.206 g / m ^{2 in} terms of solid coating amount. The coating amount of the liquid (c) was applied such that the coating amount of the electron donating dye (H) contained in the liquid was 0.355 g / m ^{2 in} terms of solid content coating amount.
The intermediate layer coating solution has a solid coating amount of 2.39 g / m ² between (a) and (b), and a solid coating amount of 3.34 g / m between (b) and (c). m ² , the light transmittance adjusting layer coating solution was applied such that the solid content was 2.20 g / m ² , and the protective layer was applied so that the solid content was 1.39 g / m ² .

(Example 2)
A heat-sensitive recording material was used in the same manner as in Example 1 except that 3.5 parts of FA-5 and 18 parts of FB-9 were used instead of the fluorescent brightener precursors FC-1 and FD-8 of Example 1. Was made.

(Example 3)
Heat sensitive in the same manner as in Example 1 except that 4.0 parts of FE-5 and 18.5 parts of FF-7 were used instead of the fluorescent brightener precursors FC-1 and FD-8 of Example 1. A recording material was obtained.

Example 4
In addition to adding the fluorescent brightener precursor-containing coating solution to the cyan thermosensitive recording layer coating solution (c) in Example 1, in addition to adding to the intermediate layer coating solution provided between the cyan thermosensitive recording layer and the magenta thermosensitive recording layer. Produced a thermosensitive recording material in the same manner as in Example 1. The addition ratio of the fluorescent brightener precursor-containing liquid to the intermediate layer coating liquid was such that the coating amount of the solid content in the intermediate layer was 0.19 g / m ² .

(Comparative Example 1)
In Example 1, a thermosensitive recording material was prepared in the same manner as in Example 1 except that the fluorescent brightener precursor-containing liquid was not added to the cyan thermosensitive recording layer coating liquid (c).

(Comparative Example 2)
In Example 1, in the final step of preparing the electron-donating dye precursor-encapsulated microcapsule liquid (c) of the cyan thermosensitive recording layer coating liquid, a 25% aqueous solution of sodium dodecylbenzenesulfonate (trade name; Neo) was added to the microcapsule liquid. When adding 3.7 parts of Perex F-25, manufactured by Kao Corporation, a fluorescent whitening agent (trade name; Kaycoll BXNL) containing 4,4′-bistriazinylaminostilbene-2,2′-disulfone derivative (Manufactured by Nippon Soda Co., Ltd.) and heat sensitive in the same manner as in Example 1 except that no fluorescent brightener precursor-containing solution is added to the cyan thermosensitive recording layer coating solution (c). A recording material was prepared.

[Image recording, whiteness test and fixability test]
<Image recording>
Image recording was performed by the following method using a thermal head KST (manufactured by Kyocera Corporation) and a light emitting diode.
First, the yellow thermosensitive recording layer was recorded. Printing is performed in the range of 25 to 75 mJ / mm ² as the recording energy per unit area while leaving the unprinted area, and then the light is irradiated for 20 seconds with a light emitting diode having a light emission center wavelength of 450 nm. The diazonium salt compound of the yellow thermosensitive recording layer is completely The image was fixed by photolysis. The output of the light emitting diode was set so that the yellow thermosensitive recording layer of the thermosensitive recording material in Example 1 was completely photodegraded in 20 seconds by the diazonium salt compound.
Next, the magenta thermosensitive recording layer was recorded. Printing is performed in the range of 80 to 120 mJ / mm ² as the recording energy per unit area while leaving the unprinted area, and then the light is emitted for 20 seconds with a light emitting diode having a light emission center wavelength of 380 nm. The image was fixed by photolysis. The output of the light emitting diode was set so that the diazonium salt compound was completely photodegraded in 20 seconds in the magenta thermosensitive recording layer of the thermosensitive recording material in Example 1.
Finally, as the recording energy per unit area, heat is applied to the entire surface of the recording paper by a thermal head in the range of 129 to 131 mJ / mm ² , and thereafter the recording energy per unit area is 135 to 170 mJ while leaving an unprinted portion. / Mm ² was printed, and the cyan thermosensitive recording layer was recorded.

<Whiteness test>
In the whiteness test, the white portion after image recording (the yellow, magenta and cyan thermal recording layers are unprinted portions, but thermal energy of 129 to 131 mJ / mm ² is applied per unit area). The yellow density was measured with an X-rite model 310 (X-rite, manufactured by Incorporated).

<Fixability test>
The fixability test was conducted by measuring the time required for the photo-decomposition of the diazonium salt compound completely in the magenta thermosensitive recording layer when fixing with a light emitting diode.
Table 1 shows the results of the whiteness test and the fixability test.

  From the above test results, it can be seen that by using the fluorescent whitening agent precursor of the present invention, an image having high whiteness can be obtained without extending the fixing time (printing time).

Claims (9)

  A recording material having a recording layer provided on a support, the recording material comprising a layer containing a fluorescent brightener precursor that generates a fluorescent brightener upon heating.   2. The recording material according to claim 1, wherein the recording layer is a thermosensitive recording layer, and the thermosensitive recording layer is a diazo thermosensitive recording layer containing a diazonium salt compound and a coupler.   The two-layer diazo thermosensitive recording layer comprising a combination of two diazonium salt compounds having different photosensitive wavelengths and a coupler that reacts with each diazonium salt compound to develop a different hue, and the diazo thermosensitive recording layer are: 3. The recording material according to claim 1, wherein another heat-sensitive recording layer is obtained by laminating the heat-sensitive recording layer and the two diazo heat-sensitive recording layers in order from the closest to the support. .   4. The recording material according to claim 3, wherein, of the two kinds of diazonium salt compounds, one has a maximum absorption wavelength of 445 ± 50 nm and the other has a maximum absorption wavelength of 365 ± 30 nm. The fluorescent whitening agent is an azomethine compound, and a reaction for forming the azomethine compound is represented by the following reaction formula (1-1) or (1-2): 5. The recording material according to any one of 4 above.

In the reaction formula (1-1), Ar ¹ and Ar ² each independently represent a phenyl group or an unsaturated heterocyclic residue which may have a substituent. In the reaction formula (1-2), Ar ¹ represents an optionally substituted phenyl group or an unsaturated heterocyclic residue, and Ar ³ represents an optionally substituted phenylene group. , X represents a single bond or a divalent linking group, and the substituents may form a ring. In the reaction formulas (1-1) and (1-2), L represents a hydrogen atom or a group capable of leaving when an azomethine compound is formed. The said optical brightener is a coumarin type compound, and reaction which produces | generates a coumarin type compound is represented by following Reaction formula (2), The any one of Claims 1 thru | or 4 characterized by the above-mentioned. Recording material.

In the reaction formula (2), R ¹ represents a hydrogen atom, R ⁴ (R ⁵ ) N—, or an optionally substituted alkyl, alkoxy, aryloxy, alkylthio or arylthio group, and R ² Represents a hydrogen atom, an optionally substituted acyl, alkyl, aryl, alkoxycarbonyl or heterocyclic residue, or a carboxyl group, and R ³ , R ⁴ and R ⁵ are a hydrogen atom or a substituent. An acyl, alkyl, aryl, or heterocyclic residue which may have W represents a carboxyl group, an alkoxycarbonyl group, or a cyano group. 5. The optical brightener is a styryl compound, and a reaction for forming a styryl compound is represented by the following reaction formula (3): 5. Recording material.

In the reaction formula (3), Ar ⁴ represents an optionally substituted phenyl group or an unsaturated heterocyclic residue, and R ⁶ represents a hydrogen atom, an optionally substituted alkyl or an aryl group, E ¹ and E ² showing the electron-withdrawing group.   8. The recording material according to claim 2, wherein at least one of the diazonium salt compounds is encapsulated in a microcapsule.   The recording material recording method according to any one of claims 1 to 8, wherein an image is recorded on the recording layer, and the recording material is entirely heated before or after image recording to fluoresce. A recording method comprising a step of generating a fluorescent brightener from a brightener precursor.