JPH087402B2 - Image forming material and image recording method using the same - Google Patents

Description

The present invention relates to a novel image forming material and an image recording method using the same.

More specifically, the present invention relates to a novel image forming material which can be used in applications such as proof paper, printout paper, overlay film, facsimile, printer and the like, and an image recording method using the same.

"Prior Art" Conventionally, this type of photo-image forming material has been used for many photographic applications as so-called free radical photography in which a light-sensitive portion is visualized by imagewise exposure. Also, many types of thermal recording have been known for a long time.

Particularly effective as a photoimage forming material is a method of radically coloring various leuco dyes into their corresponding dyes using a photo-oxidizing agent (for example, Photo.Sci.Eng., 5 , 98-10).
3 (1961), JP-B-43-29,407, JP-A-55-55,335
Nos. 57-60,329 and 62-66,254).

Regarding heat-sensitive recording, for example, a heat-sensitive recording material using an electron-donating dye precursor and an electron-accepting compound is disclosed in JP-B-45-45.
-14,039, 43-4160 and the like. Also,
A heat-sensitive recording material using a diazo compound is disclosed in JP-A-59-190,
No. 886, etc.

"Problems to be solved by the invention" In recent years, these image recording materials have been used in addition to photographic applications.
It has been applied to various fields such as facsimiles, printers, labels, etc., and its needs are expanding, but since they are sensitive to light and heat, even after forming an image, ordinary room light, sunlight or It has the essential drawback of producing light fog and thermal fog when exposed to white light, making it difficult to handle such imaging materials.

In order to retain the image once formed, subsequent color development, which obscures the presence of the image during storage, must be avoided.

 In optical image recording systems, for example, spray or
Free radical scavenger by immersion (hydroquinone
Etc.) to the imaged material.
It is known to save the original image by. this child
Is an advantage for storing or fixing the original image.
Workability associated with going through the wet process,
It complicates operability. Also, Du Pont
Dylux Image formation with UV light like
It is treated with only light that will fix the material by activating the reducing substance.
There are commercially available materials that have the
It However, this process uses light twice
To monopolize the device for that time, and
Is it necessary to replace the spectroscopic filter?
It is said that the processing speed is unsatisfactory depending on the usage.
It has a drawback. Furthermore, the specification of Japanese Examined Patent Publication No. 43-29,407
In the binder solution with the leuco dye and photo-oxidizing agent
Contains a reducing heat fixing agent, or the heat fixing
After applying the agent on the photosensitive layer, heat fixing after image exposure
There is a description to do. However, these methods
Is, in reality, a light-sensitive part (leuco dye and photo-oxidizer)
And the fixer coexist in close proximity, resulting in poor sensitivity over time.
It is not preferred because

On the other hand, the photoimage forming material consisting of these leuco dyes and photooxidants is usually uniformly dissolved in an organic solvent and applied (or dipped, cast, etc.) on a support such as paper or plastic film, and the solvent is dried. To remove by evaporation. Therefore, it is necessary to take explosion-proof measures such as manufacturing facilities associated with the use of such a volatile organic solvent, which is disadvantageous in terms of safety and cost.

Further, in the heat-sensitive recording system, a heat-sensitive recording method in which a fixing property is imparted by applying a coupling color reaction and a photodecomposability of a diazo compound and a coupler is disclosed (for example, JP-A-57-123,086 and 57-57). −44,141, 57
-142,636, 57-192,944, etc.). However, since reactive components (diazo compounds, couplers, bases, etc.) are incorporated in the same layer, fog is liable to occur during storage before recording, and a satisfactory one has not been obtained. Further, a heat-sensitive recording material in which one of the above reactive components is encapsulated in microcapsules is disclosed in JP-A-59-190886, and there are some which have excellent image storability and fixability. However, since these all use diazo compounds, it cannot be said that the preservability before recording is always sufficient, and it is preferable to use safer materials including couplers and bases.

"Object of the Invention" The object of the present invention is to provide an image forming material having excellent image reproducibility, raw storability, and image storability (fixing property), and further, it is completely dry and simple in the image forming and fixing process. To provide a simple recording method.

Another object of the present invention is to provide an image forming material in which handling in an organic solvent system, which is disadvantageous in terms of production suitability, is reduced or unnecessary.

"Means for Solving the Problem" An object of the present invention is that at least one selected from leuco dyes capable of oxidative coloring and at least one selected from photooxidants have a wall that increases the permeability of a substance by heating. An image-forming material which is encapsulated in microcapsules, and on the outside of the microcapsules, at least one selected from a reducing agent is present,
After the image-forming material is irradiated with light to form an image, the image-forming material is heated to bring the photo-oxidizing agent and the reducing agent into contact with each other, or an image is formed by heating the image-forming material. The image recording method is characterized by exposing the entire surface after forming a latent image.

The most characteristic feature of the image forming material of the present invention is the use of microcapsules. That is, the basic function of the microcapsule is: (1) Each component can be microscopically separated inside and outside the microcapsule.

(2) By encapsulating something inside the microcapsule,
The influence of the external environment (especially moisture, oxygen, storage temperature, etc.) is reduced as much as possible, and the inclusions can be stored stably.

(3) If necessary, the contents inside or outside the capsule can be reacted by taking out the contents of the capsules by external stimulation (for example, heat or pressure) or by introducing the external additives into the capsules.

(4) Even if the core material of the capsule is an organic solvent system such as oil, the entire capsule dispersion system can be treated as an aqueous system.

Etc.

In the present invention, the above functions (1) and (2) are used to improve the stability of the system, the functions (1) and (3) are used as means for a simple recording method such as heat fixing after exposure, and ( The function of 4) is used as an improvement in manufacturing suitability.

Preferred capsules in the present invention are those which at normal temperature prevent the contact of the substance inside and outside the capsule by the substance sequestering action of the microcapsule wall, and increase the permeability of the substance only when heated to a certain temperature or higher. With respect to this phenomenon, the permeation initiation temperature can be freely controlled by appropriately selecting the capsule wall material, the capsule core substance, and the additive. The permeation initiation temperature in this case corresponds to the glass transition temperature of the capsule wall (eg, JP-A-59-91,438).
No. 59-190,886, Japanese Patent Application No. 59-99,490, etc.).

To control the glass transition temperature inherent in the capsule wall, it is necessary to change the type of the capsule wall forming agent. Examples of the microcapsule wall material that can be used in the present invention include polyurethane, polyurea, polyester, polycarbonate, urea-formaldehyde resin, melamine-
Examples thereof include formaldehyde resin, polystyrene, styrene-methacrylate copolymer, gelatin, polyvinylpyrrolidone, polyvinyl alcohol and the like. Moreover, two or more kinds of these polymer substances can be used in combination.

In the present invention, among the above polymer substances, polyurethane, polyurea, polyamide, polyester, polycarbonate and the like are preferable, and polyurethane and polyurea are particularly preferable.

The microcapsule used in the present invention is obtained by emulsifying a core substance containing a reactive substance such as a leuco dye and a photo-oxidizing agent, and then forming a wall of a polymer substance around the oil droplet to form a microcapsule. In this case, the high molecular substance forming reactant is added to the inside of the oil droplet and / or the outside of the oil droplet. Details of microcapsules that can be preferably used in the present invention, such as a preferred method for producing microcapsules, are described in U.S. Pat.
No. 96,696.

For example, when polyurethane urea is used as a capsule wall material, a polyisocyanate and a second substance (for example, a polyol) which reacts with the polyisocyanate to form a capsule wall are mixed in an aqueous phase or an oily liquid to be encapsulated and then emulsified and dispersed in water. Then, by raising the temperature, a polymer forming reaction occurs at the oil drop interface to form a microcapsule wall. If the second additive is, for example, a polyamine or, if nothing is added, polyurea is formed.

In this case, the polyvalent isocyanate to be used and the polyol and polyamine to be reacted therewith are described in U.S. Pat. Nos. 3,281,383, 3,773,695 and 3,793,268, and Japanese Patent Publication No.
-40347, 49-24159, JP-A-48-80191, 48
-84086, they can also be used.

Examples of the polyvalent isocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate and diphenylmethane-4,4 '. -Diisocyanate, 3,
3'-dimethoxy-4,4'-biphenyl-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, 4,
4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-
Diisocyanates such as 1,2-diisocyanate, cyclohexylene-1,2-diisocyanate and cyclohexylene-1,4-diisocyanate, 4,4 ′, 4 ″ -toluphenyl methane triisocyanate, toluene-2,4,6-triisocyanate Triisocyanates such as isocyanates, tetraisocyanates such as 4,4'-dimethyldiphenylmethane-2,2 ', 5,5'-tetraisocyanate, adducts of hexamethylene diisocyanate and trimethylolpropane, 2,4-tolylenediene There are isocyanate prepolymers such as adducts of isocyanate with trimethylolpropane, xylylene diisocyanate with trimethylol propane, and tolylene diisocyanate with hexanetriol.

Examples of polyols include aliphatic and aromatic polyhydric alcohols, hydroxypolyesters, and hydroxypolyalkylene ethers.

The following polyols described in JP-A-60-49991 can also be used. Ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol,
1,6-hexanediol, 1,7-heptanediol, 1,8
-Octanediol, propylene glycol, 2,3-dihydroxybutane, 1,2-dihydroxybutane, 1,3-dihydroxybutane, 2,2-dimethyl-1,3-propanediol, 2,4-pentanediol, 2, 5-hexanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, dihydroxycyclohexane,
Diethylene glycol, 1,2,6-trihydroxyhexane, 2-phenylpropylene glycol, 1,1,1-trimethylolpropane, hexanetriol, pentaerythritol, pentaerythritol ethylene oxide adduct, glycerin ethylene oxide adduct, glycerin, 1,4-di (2-hydroxyethoxy) benzene,
Condensation product of an aromatic polyhydric alcohol such as resorcinol dihydroxyethyl ether and an alkylene oxide, p-xylylene glycol, m-xylylene glycol, α, α′-dihydroxy-p-diisopropylbenzene, 4,4′-dihydroxy -Diphenylmethane, 2
-(P, p'-dihydroxydiphenylmethyl) benzyl alcohol, an adduct of ethylene oxide with bisphenol A, an adduct of propylene oxide with bisphenol A, and the like. The polyol is preferably used in such a manner that the ratio of the hydroxyl group is 0.02 to 2 mol with respect to 1 mol of the isocyanate group.

Examples of polyamines include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, p-phenylenediamine, m-phenylenediamine, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine and 2-hydroxy. Examples include trimethylenediamine, diethylenetriamine, triethylenetriamine, triethylenetetramine, diethylaminopropylamine, tetraethylenepentamine, and amine adducts of epoxy compounds. Polyvalent isocyanates can also react with water to form polymeric substances.

Here, the organic solvent for forming the oil droplets can generally be appropriately selected from high-boiling oils, such as phosphoric acid ester, phthalic acid ester, acrylic acid ester, methacrylic acid ester, and other carboxylic acid ester. , Fatty acid amide, alkylated biphenyl, alkylated terphenyl, chlorinated paraffin, alkylated naphthalene, diarylethane and the like are used. Specifically, those described in JP-A-60-242,094 and Japanese Patent Application No. 62-75,409 can be used.

In the present invention, an auxiliary solvent may be further added to the above-mentioned organic solvent as a low boiling point dissolution aid. As such an auxiliary solvent, for example, ethyl acetate, isopropyl acetate, butyl acetate, methylene chloride and the like can be mentioned as particularly preferred.

On the other hand, a water-soluble polymer to be contained as a protective colloid in an aqueous phase mixed with an oil phase is a known anionic polymer,
Although it can be appropriately selected from nonionic polymers and amphoteric polymers, polyvinyl alcohol, gelatin, cellulose derivatives and the like are preferable.

As the surfactant to be contained in the aqueous phase, it is possible to appropriately select and use anionic or nonionic surfactants that do not cause precipitation or aggregation by acting on the protective colloid. . Preferred surfactants include sodium alkylbenzene sulfonate (eg sodium lauryl sulfate), dioctyl sodium sulfosuccinate, polyalkylene glycols (eg polyoxyethylene nonylphenyl ether) and the like.

In the present invention, the size of the microcapsules, especially from the viewpoint of image resolution improvement and storability, handleability,
For example, the volume average particle size according to the measuring method described in JP-A-60-214,990 is preferably 20 μm or less, and particularly preferably 4 μm or less. Further, if the capsule is too small, it may be erased in the pores or fibers of the matrix, and this depends on the properties of the matrix or support, so it cannot be said unconditionally, but 0.1 µ or more is preferable.

Next, the leuco dye constituting one component of the image forming material of the present invention will be described. The leuco dyes which can be used in the present invention are in the reduced form having one or two hydrogen atoms and forming a dye by removal thereof and in some cases addition of an additional electron to form a dye. Including dyes. Such leuco dyes are substantially colorless, or have a weak color when hot, and thus are a means of forming a pattern when oxidized and colored. This oxidation is accomplished in the present invention by the presence of at least one photooxidant. The photooxidant is activated by irradiation with light and splits into free radicals. The part where these free radicals come into contact with the leuco dye produces a colored image with respect to the background which has not been contacted.

Leuco dyes that can be readily colored by oxidation by the above mechanism include, for example, those described in US Pat. No. 3,445,234, which is hereby incorporated by reference.

(A) Aminotriarylmethane (b) Aminoxanthene (c) Aminothioxanthene (d) Amino-9,10-dihydroacridine (e) Aminophenoxazine (f) Aminophenothiazine (g) Aminodihydrophenyl Nadine (h) Aminodiphenylmethane (i) Leucoindamine (j) Aminohydrocinnamic acid (cyanoethane, leucomethine) (k) Hydrazine (l) Leucoin digoid dye (m) Amino-2,3-dihydroanthraquinone (N) Tetrahalo-p, p'-biphenol (o) 2- (p-hydroxyphenyl) -4,5-diphenylimidazole (p) phenethylaniline Among these leuco dyes, from (a) to ( The dyes up to i) are colored by losing one hydrogen atom to form dyes, while the leuco dyes (j) to (p) are dyed. One of the hydrogen atoms to produce a loss of connexion parent dye. Of these, aminotriarylmethane is preferred. A generally preferred class of aminotriarylmethanes is such that at least two of the alur groups are (a) R ₁ and R ₂ are each hydrogen, and C _1-
R ₁ R ₂ N-substituent in para position to the bond to the methane carbon atom, such as a group selected from C ₁₀ alkyl, 2-hydroxyethyl, 2-cyanoethyl, or benzyl, and (b) lower A phenyl group having a group ortho to a methane carbon atom selected from alkyl (C is 1 to 4), lower alkoxy (C is 1 to 4), fluorine, chlorine, or bromine; The aryl group of may be the same as or different from the first two, and if different, (a) lower alkyl, lower alkoxy, chlorine, diphenylamino, cyano, nitro, hydroxy, fluorine or bromine, alkylthio, Arylthio, thioester, alkyl sulfone, aryl sulfone, sulfonic acid, sulfonamide, alkylamide, arylamide, etc. (B) amino, di-lower alkylamino, naphthyl that may be substituted with alkylamino; (c) pyridyl that may be substituted with alkyl; (d) quinolyl; (e) indolinylidene that may be substituted with alkyl. It is a type of aminotriarylmethane and its acid salt which is characterized by being more selected. Preferably, R ₁ and R ₂ are hydrogen or alkyl of 1-4 carbon atoms. Most preferably all three alur groups are the same.

The triarylmethane or other leuco dye having the above-mentioned structure causes a color-forming dark reaction which causes fog or coloring when applied to a photographic film, paper or other system as a conventional photoimage forming material. I may receive it.

However, these leuco dyes can be used in the novel material using the capsule in the present invention. This is because the color-forming dark reaction can be prevented by the capsules having the same effect as storing such compositions in the absence of air.

On the other hand, the preferred photo-oxidizing agent that can be used in the image-forming material of the present invention is inactive until exposed to actinic radiation such as visible rays, ultraviolet rays, infrared rays and X-rays. Various photo-oxidants have different peak sensitivities throughout the spectrum, depending on the structure of the compound. As such, the particular photooxidant selected depends on the nature of the actinic radiation. When exposed to such radiation,
The photo-oxidant produces an oxidant that oxidizes the color-forming agent to its color-forming form.

Typical photo-oxidizing agents include carbon tetrabromide, N-bromosuccinimide, halogenated hydrocarbons such as tribromomethylphenyl sulfone described in U.S. Pat. Nos. 3,042,515 and 3,502,476, The Photographic Society of Japan Spring 1968. Abstracts of research presentations Azido polymer described on page 55, US Patent No.
2-azidobenzoxazole, benzoyl azide, azido compounds such as 2-azidobenzimidazole described in 3,282,693, and 3'ethyl-1-methoxy-2-pyridothiacyanine perchlorate, 1-described in U.S. Pat. Compounds such as methoxy-2-methylpyridinium p-toluenesulfonate, JP-B-62-39,7
No. 28, 2,4,5-triarylimidazole dimer compounds such as loffin dimer compounds, benzophenone, p-
A compound such as aminophenyl ketone, polynuclear quinone, thioxanthenone, and at least one photooxidant compound from the group consisting of mixtures of the above compounds,
It is not limited to this.

Of these, the luffin dimer compound and the organic halogen compound are preferable, and the combination of the two is most suitable because it is possible to realize high sensitivity in light irradiation color development.

The loffin dimer compound is represented by the following formula. Upon dissociation, the dimer forms the corresponding 2,4,5-triarylimidazolyl group.

(Wherein A, B and D may be the same or different and unsubstituted or may be a carbocycle or heterocycle substituted with a substituent that does not inhibit the dissociation of the dimer to the imidazolyl group or the oxidation of the leuco dye) The groups B and D usually have 0 to 3 substituents and the group A has 0 to 4 substituents. Useful loffin dimer compounds and their methods of preparation are described in US Pat.
No. 4, column 22, line 2 to column 6, line 3.

Specific examples of the loffin dimer compound include compounds having the following structures.

.2,2'-bis- (o-chlorophenyl) -4,4 ', 5,5'
-Tetraphenyl biimidazole .2,2'-bis- (o-trifluoromethylphenyl)
−4,4 ′, 5,5′-Tetraphenylbiimidazole -2- (2,3-dichlorophenyl) -4,5-bis- (3,4
-Methylenedioxyphenyl) -biimidazole The organic halogen compound used in combination with the above luffin dimer compound is a solid or liquid compound having 40 or less carbon atoms in the molecule. Specifically (1) General formula R-CX ₃ (wherein R is hydrogen, halogen, an aryl group, X is a halogen), a compound represented by, for example, carbon tetrachloride, carbon tetrabromide, p
-Nitrobenzotribromide, bromotrichloromethane, benzotrichloride, hexabromoethane, iodoform, 1,1,1-tribromo-2-methyl-2-propanol, 1,1,2,2-tetrabromoethane, 2, 2,2-tribromoethanol, 1,1,1-toluchloro-2-methyl-
2-propanol, (2) general formula (In the formula, Rx represents hydrogen or 1 to 5 substituents on the benzene ring, and these substituents are all substituents such as nitro group, halogen group, alkyl group, haloalkyl group, acetyl group, haloacetyl group and alkoxy group. Are not necessarily the same), for example o-nitro-α, α, α-tribromoacetophenone, m-nitro-α, α, α-tribromoacetophenone, p-nitro -Α, α, α-tribromoacetophenone, α, α, α-tribromoacetophenone, α, α, α-tribromo-3,4-cycloloacetophenone, (3) general formula R- SO ₂ —X (wherein R is an alkyl group, an arule group (including those having a substituent) and X is a halogen), for example, 1,3-benzenesulfonyl chloride, 2,4-dinitrobenzenesulfonyl chloride , O-nit Benzenesulfonyl chloride, m- nitrobenzenesulfonyl chloride, 3,3'-diphenyl sulfone dicarboxylic chloride, ethanesulfonyl chloride, p- bromobenzenesulfonyl chloride, p- nitrobenzenesulfonyl chloride, p-3
-Dobenzenesulfonyl chloride, p-acetamidobenzenesulfonyl chloride, p-chlorobenzenesulfonyl chloride, p-toluenesulfonyl chloride, methanesulfonyl chloride, benzenesulfonyl chloride, (4) General formula R-S-X (wherein R is an alkyl group) , An aryl group (including those having a substituent), X is a halogen), for example, 2,4-dinitrobenzenesulfenyl chloride, o-nitrobenzenesulfenyl chloride, (5) the general formula Or (Wherein R is a substituted or unsubstituted aryl group, heterocyclic ring residues are X ₁ , X ₂ , and X ₃ are hydrogen, and halogen is not all hydrogen at the same time), for example, hexabromo Dimethyl sulfoxide, pentabromodimethyl sulfoxide,
Hexabromodimethyl sulfone, trichloromethylphenyl sulfone, tribromomethylphenyl sulfone, trichloromethyl-p-chlorophenyl sulfone, tribromomethyl-p-nitrophenyl sulfone, 2-trichloromethylbenzothiazole sulfone, 4,6- Dimethylpyrimidine-2-tribromomethylsulfone, tetrabromodimethylsulfone, 2,4-dichlorophenyl-trichloromethylsulfone, 2-methyl-4-chlorophenyl-trichloromethylsulfone, 2,5-dimethyl-4-
Chlorophenyl-trichloromethyl sulfone, 2,4-dichlorophenyl-tribromomethyl sulfone, (6) General formula (Wherein R is a heterocyclic compound residue which may have a substituent. X ₁ , X ₂ and X ₃ are hydrogen or halogen and are not all hydrogen at the same time), for example, Tribromoquinaldine, 2-
Tribromomethyl-4-methylquinoline, 4-tribromomethylpyrimidine, 4-phenyl-6-tribromomethylpyrimidine, 2-trichloro-methyl-6-nitrobenzothiazole, 1-phenyl-3-trichloromethylpyrazole, 2 , 5-Ditribromomethyl-3,4-dibromothiophene, 2-trichloromethyl-5- (p-butoxystyryl) -1,3,4-oxadiazole, 2,6-ditrichloromethyl-4- Organic halogen compounds such as (p-methoxyphenyl) -triazine and the like can be mentioned.

Among these, the compounds of (2), (5) and (6) are preferable, and as the halogen, chlorine, bromine and iodine are preferable.

In the production of the image-forming material of the present invention, good results are obtained by mixing the leuco dye and the photo-oxidizing agent in a molar ratio of about 10: 1 to about 1:10. A more desirable ratio is 2:
1 to 1: 2.

The combined use ratio of the two photo-oxidizing agents is 0.05 to 100 mol, preferably 0.2 to 10 mol, of the organic halogen compound to 10 mol of the luffin dimer compound.

The image-forming material of the present invention is stabilized by subjecting it to image formation by exposure, for example, by subjecting it to heat treatment, or by subjecting the entire surface to exposure after recording an image-like latent image with a minute heating element such as a thermal head. A reliable image can be obtained. That is, the fixing mechanism of the image forming material of the present invention is such that the photooxidizing agent and the reducing agent come into contact with each other through the capsule wall by heating, and the reducing agent acts even if the photooxidizing agent is subsequently activated. Deactivate the oxidant,
This is because the leuco dye no longer develops color.

Such a reducing agent typically acts as a so-called free radical scavenger that traps the free radicals of the activated photo-oxidizing agent, and all known reducing agents can be used. Things are included.

For example, an organic reducing agent having a hydroxyl group on the benzene ring described in U.S. Pat. No. 3,042,515 and having at least another hydroxyl group or an amino group at another position of the benzene ring (for example, hydroquinone, catechol, resorcinol, hydroxyhydroquinone , Pyrrologricinol and o-aminophenol, aminophenols such as p-aminophenol, etc.), or a cyclic phenylhydrazide compound described in the specification of JP-B-62-39728, such as 1-phenylpyra. Zolidin-3-one [phenidone A,
The following formula (1)], 1-phenyl-4-methylpyrazolidin-3-one [phenidone B, the following formula (2)], 1
-Phenyl-4,4-dimethylpyrazolidin-3-one [dimesone, the following formula (3)], 3-methyl-1-
(P-sul Examples thereof include fophenyl) -2-pyrazolin-5-one and 3-methyl-1-phenyl-2-pyrazolin-5-one.

However, the following substituents can be present on the phenyl group of the cyclic phenylhydrazide. O-, m- and p-methyl, p-trifluoromethyl, m- and p-chloro, m- and p-bromo, p-fluoro, o-, m-
And p-methoxy, p-ethoxy, p-benzyloxy, p-butoxy, p-phenoxy, 2,4,6-trimethyl, 3,4-dimethyl. The following substituents can be present at the 4-position on the heterocyclic group of the cyclic phenylhydrazide.
Bis-hydroxymethyl, hydroxymethyl and methyl,
Hydroxymethyl, dimethyl, dibutyl, ethyl, benzyl. The following substituents may be present at the 5-position on the heterocyclic group of the cyclic phenylhydrazide: dimethyl, methyl, phenyl.

Further, a compound selected from a guanidine derivative, an alkylenediamine derivative and a hydroxyamine derivative can be used. Specifically, as the guanidine derivative, for example, phenylguanidine, 1,3-diphenylguanidine, 1,2,3-triphenylguanidine, 1,2-dicyclohexylguanidine, 1,2,3-tricyclohexylguanidine, 1,3-di-o-tolylguanidine, o-tolyldiphenylguanidine, m-tolyldiphenylguanidine, p-tolyldiphenylguanidine, N, N′-dicyclohexyl-4-morpholinocarboxamidine, 1,
Examples thereof include 3-ditolyl-3-phenylguanidine, 1,2-dicyclohexylphenylguanidine, 1-o-tolylbiguanide and N-benzylidene-guanidinoamine.

The chemical structural formulas of typical guanidine derivatives are shown below.

・ 1,2,3-Triphenylguanidine ・ 1,2,3-Tricyclohexylguanidine Examples of the alkylenediamine derivative include ethylenediamine, propylenediamine, tetramethylenediamine, hexamethylenediamine, octamethylenediamine, 1,1,2-diaminododecane and tetrabenzylethylenediamine.

The chemical structural formulas of typical alkylenediamine derivatives are shown below.

・ Ethylenediamine H ₂ N (CH ₂ ) ₂ NH ₂・ Tetrabenzylethylenediamine Examples of the hydroxyamine derivative include diethanolamine, triethanolamine, 3-β-naphthyloxy-1-N, N dimethylamino-2-propanol and the like.

The reducing agent acting as a free radical trapping substance described above can be used alone or in combination of two or more. However, any reducing substance having a function capable of acting on a so-called oxidizing agent is not limited thereto. is not.

In the image-forming material of the present invention, the leuco dye and the photo-oxidizing agent are both encapsulated in microcapsules, but the reducing agent not encapsulated is either solid-dispersed by a sand mill or the like, or emulsified after dissolution in oil. It is better to use it dispersedly.

In the case of solid dispersion, it is dispersed in a water-soluble polymer solution having a concentration of 2 to 30% by weight, and a preferable dispersed particle size is 10 μm or less. Preferred water-soluble polymers include water-soluble polymers used for making microcapsules. The emulsification / dispersion can be carried out by referring to the methods and materials described in the specification of Japanese Patent Application No. 62-75,409.

The preferred amount of reducing agent is 1 to
Although it can be used in a 100-fold molar amount, a range of 1 to 10-fold molar amount is more preferable in order to obtain a desired result in the smallest possible amount.

In the present invention, a known sensitizer may be added and used as an additional component of the photooxidant. For example, Katsumi Tokumaru, edited by Shin Okawara, "Sensitizer", Kodansha 1987 64-75
The compounds described on the page can be mentioned. Specifically, aromatic ketones, acetophenones, diketones, carbonyl compounds such as acyloxime esters, aromatic thiols, mono- and disulfides, thioureas,
Examples thereof include sulfur compounds such as dithiocarbamates, organic peroxides such as benzoyl peroxide, azo compounds such as azobisisobutyronitrile, and halides such as N-bromosuccinimide. Examples of sensitizing dyes in the visible region include dyes having an amidinium ion-based, carboxyl ion-based, or bipolar amide-based chromophore described on pages 106 to 123 of the same book. Specifically, cyanine-based, phthalein-based, and oxonol-based dyes are representative.

In the present invention, an auxiliary agent for the purpose of improving heat fixing or heat recording efficiency can be used. This auxiliary agent has the action of lowering the melting point of each component constituting the system and the softening point of the capsule wall.

Such auxiliary agents include phenol compounds, alcoholic compounds, amide compounds, sulfonamide compounds and the like, and specific examples thereof include p-tert-octylphenol, p-benzyloxyphenol, p-oxybenzoic acid phenyl, Benzyl carbanylate, phenethyl carbanylate, hydroquinone dihydroxyethyl ether,
Examples thereof include compounds such as xylylenediol, N-hydroxyethyl-methanesulfonic acid amide, and N-phenyl-methanesulfonic acid amide. These may be contained in the core substance or may be added outside the microcapsules as an emulsified dispersion.

In the present invention, a known stabilizer such as an antioxidant may be added to the capsule for use. The function of the stabilizer here is, of course, a substance having a function similar to that of the above-mentioned reducing agent, although the purpose of use is different, so it is necessary to stop the use amount to the minimum necessary. Accordingly, specifically, in addition to the above-mentioned free radical trapping substance, the compounds described in the specification of U.S. Pat.
The 2,4-dihydroxyaldoxime and the like described in the specification of No. 5,335 can be mentioned, but the amount of the stabilizers used is about 0.01 mol% to about 25 mol% based on the photooxidant. Is preferable, and the range of 0.1 mol% to 10 mol% is the most preferable.

The image forming material of the present invention can be prepared by coating, impregnating or forming a self-supporting layer on a support as a dispersion of microcapsules containing such a leuco dye and a photo-oxidizing agent and a reducing agent.

At this time, as a binder that can be added to the dispersion,
Polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, gum arabic, gelatin, polyvinylpyrrolidone, casein, styrene-butadiene latex, acrylonitrile-butadiene latex, polyvinyl acetate, polyacrylic ester, ethylene-vinyl acetate copolymer Various emulsions such as coalesced can be used. The amount is in terms of the solid content ^{0.5g / m 2 ~5g / m 2} .

The coating amount of the image forming material of the present invention is 3 g / m in terms of solid content.
^{2 ~30g} / m ^2, it is preferable that particularly is between ^{5g / m 2 ~20g / m 2} . If it is 3 g / m ² or less, a sufficient concentration cannot be obtained, and even if it is applied at 30 g / m ² or more, the quality is not improved, which is a cost disadvantage.

Suitable materials for the support include papers from tissue paper to thick cardboard, recycled cellulose, cellulose acetate, cellulose nitrate, polyethylene terephthalate, vinyl polymers and copolymers, polyethylene, polyvinyl acetate, polymethylmethacrylate. , Films of plastics and polymeric materials such as polyvinyl chloride; woven fabrics; materials commonly used in graphic arts and decorative applications such as glass, wood and metal.

When applying to a support, generally well-known coating methods, for example, day coat method, air knife coat method, curtain coat method, roller coat method, doctor coat method, wire bar coat method, slide coat method,
Gravure coating method, spin coating method or US patent 2,
It can be applied by the extrusion coating method using the hopper described in the specification of No. 681,294.

In the present invention, the method of forming a latent image of an image by heating is exactly the same as in ordinary thermal recording and can be performed using an ordinary thermal head.

In the subsequent process of imagewise exposure for image fixing or image formation by light irradiation, any convenient light source may be used for forming a color image of a leuco dye by activating a photooxidant. it can. The illuminating light may be natural or artificial, monochromatic or non-coherent or coherent light and must be sufficiently dense for proper activation of the imaging composition.

Conventional light sources include fluorescent lamps, mercury, metal additions and arc lamps. Coherent light sources are pulsed nitrogen lasers, xenon lasers, argon ion lasers, and ionized neon lasers whose emission is within or overlaps the UV or visible absorption band of the photo-oxidant. UV and near visible light emitting-cathode ray tubes, which are widely used in printout systems for writing on light-sensitive materials, are also useful in the imaging materials of this invention.

If the image is formed by light irradiation, the image is by writing with a beam of activating light or by exposing selected areas of the back of a negative, stencil or other relatively opaque pattern with such light. It may be formed.
The negative may be silver on a film of cellulose acetate or polyester or such that its opacity occurs due to the agglomeration of regions with different refractive indices. Image formation is accomplished in conventional diazo printing equipment, graphic art exposure or electronic flash equipment, and in US Pat.
It may also be performed by the procedure described in 3,661,461.

In both cases of image formation by light irradiation and fixing after forming an image latent image by heat, the exposure time is the density and spectral energy distribution of light, the distance between the composition forming the image forming material and the light source, A fraction, depending on the nature and amount of the composition to be applied, and the density of color in the desired image
It can vary from seconds to minutes.

When an image is formed by light irradiation, the photo-oxidizing agent and the reducing agent can be brought into contact with each other after image exposure to fix the image. Various methods can be applied to bring them into contact with each other.

For example, there is a method of heating. In this method, by raising the temperature of the microcapsule wall to a temperature above its glass transition point, the photo-oxidizing agent and the reducing agent pass through the wall of the softened microcapsule and come into contact with each other. The glass transition point of the microcapsule wall differs depending on the material used, and therefore the heat treatment conditions necessary for fixing can be appropriately selected in consideration of these.

As another method, there is a method of destroying the microcapsule with a mechanical force and bringing them into contact with each other. In this method, a material having a high glass transition point can also be used. The force required for destruction is
It may vary depending on the material and particle size, but can be easily determined by those skilled in the art.

Furthermore, it is possible to expect a synergistic effect by simultaneously performing heating and pressurization.

Further, in order to impart fixability to an image forming material composed of a leuco dye capable of oxidative coloring and a photo-oxidizing agent, only a reducing agent is added,
Alternatively, in the embodiment of the present invention, the reducing agent can be further included in microcapsules.

The image-forming material of the present invention is used as an image-forming material having excellent manufacturing suitability and excellent image-forming property, raw storability and image storability. Examples will be shown below, but the present invention is not limited thereto. In addition, "part" indicating the amount means "part by weight" unless otherwise specified.

"Example" Example 1 The following image forming materials were prepared.

Sample (1): Leuco dye 1.5 parts of leuco crystal violet Photo-oxidizer 2,2'-bis- (o-chlorophenyl)-
4,4 ', 5,5'-Tetraphenylbiimidazole 3.0 parts Methylene chloride 12 parts Tricresyl phosphate 24 parts Takenate D-110N (75 wt% ethyl acetate solution) (Takeda Yakuhin Kogyo Co., Ltd. (trade name)) 24 parts are mixed, and polyvinyl alcohol 8 wt% aqueous solution 63 parts Then, the mixture was added to an aqueous solution containing 100 parts of distilled water and then emulsified and dispersed at 20 ° C. to obtain an emulsion having an average particle size of 1 μm. Furthermore, the obtained emulsion was continuously stirred at 40 ° C. for 3 hours. Thereafter, the temperature was returned to room temperature, followed by filtration to obtain an aqueous capsule dispersion liquid.

Next, polyvinyl alcohol 4% by weight aqueous solution 150 parts Reducing agent 1-phenylpyrazolidin-3-one (phenidone A) 30 parts Mix and mix Dyno Mill (Willie A. Bakoven.
Dispersed by A.G. (trade name), average particle size 3
A μ phenidone A dispersion was obtained.

9 parts of the above capsule liquid and 6 parts of phenidone A dispersion liquid are mixed and spin-coated on art paper at a rotation speed of 150 rpm.
It heat-dried at 1 degreeC for 1 minute, and obtained the sample (1).

The obtained sample (1) was irradiated with light from a jet light (ultra high pressure mercury lamp, manufactured by Oak Co., Ltd.) through a line drawing original, and the reflection densities in the visible region of the exposed portion and the unexposed portion were calculated by Macbeth RD- Measured with a 918 type densitometer. First result
Shown in the table.

Next, the sample (1) after the image formation was heated at a temperature of 120.
It is passed through a heating roller at 45 ° C (about 20 ° C higher than the glass transition temperature of the capsule wall according to the dynamic viscoelasticity measurement) at a speed of 45 mm / min to promote the permeability of the capsule wall due to heat and to fix it Contact). As a result, this sample was then subjected to 5
No change in the image was observed despite the double irradiation of the entire surface.

From the above results, it can be seen that the image forming material of the present invention has excellent image reproducibility and image storability (fixability).

Examples 2 and 3 1-phenyl-instead of phenidone A as reducing agent
Samples (2) and (3) were prepared in the same manner as in Example 1 except that 4-methylpyrazolidin-3-one [phenidone B] or hydroquinone was used. The chemical structural formula of 1-phenyl-4-methylpyrazolidin-3-one is shown below.

These were evaluated in the same manner as the sample (1), and similar results were obtained.

Example 4 A sample (4) was prepared in the same manner as in Example 1 except that 1,2,3-triphenylguanidine was used as the reducing agent in place of 1-phenylpyrazolidin-3-one. After exposure by the same method as in Example 1, the reflection density was measured. The results are shown in Table 2.

Next, the sample (4) after the image formation was subjected to the same fixing operation as in Example 1 and then to the same whole surface light irradiation, but no change in the image was observed.

The chemical structural formula of 1,2,3-triphenylguanidine is shown below.

Examples 5 and 6 Tetrabenzylethylenediamine or 3-β-naphthyloxy-1-N, N-dimethylamino-2-propanol was used instead of 1,2,3-triphenylguanidine as the reducing agent. Samples (5) and (6) were prepared in the same manner as in Example 1. These were evaluated in the same manner as the sample (1), and the same results were obtained.

Below, tetrabenzyl ethylenediamine and 3-β
1 shows the chemical structural formula of -naphthyloxy-1-N, N-dimethylamino-2-propanol.

Examples 7 to 10 The image forming materials shown below were prepared.

Sample (7): Leuco dye (leuco yellow dye) (4- [N-ethyl-N- {2-hydroxy-3-phenoxy-propyl} amino] -2-methylbenzylmalononitrile) carbanilate ester 1.5 parts p-Toluenesulfonic acid 0.6 part Photo-oxidizer 2,2'-bis- (o-chlorophenyl)-
4,4 ', 5,5'-Tetraphenylbiimidazole 3.0 parts Methylene chloride 12 parts Tricresyl phosphate 24 parts Takenate D-110N 24 parts were mixed, and the following were all applied in the same manner as sample (1). Paper was prepared and a sample (7) was obtained.

Sample (8): Sample (7) except that p-dibutylaminophenyltricyanoethane: (leuco magenta dye) was used in place of the leuco yellow dye of Sample (7). Sample (8) was obtained in the same manner as above.

Sample (9): Tris- (2-methyl-4-diethylamino-phenyl) methane: (leuco cyan dye) was used instead of the leuco yellow dye of sample (7). A sample (9) was obtained in the same manner as the sample (7).

Sample (10): 0.3 part of the leuco magenta dye and bis (2) instead of the leuco yellow dye of sample (7)
-Methyl-4-diethylaminophenyl) (4-diethylaminophenyl) methane: (leuco green dye) 1.
Except using 4 parts A sample (10) was obtained in the same manner as the sample (7).

Image exposure was performed on the above samples in the same manner as in Example 1 to obtain clear colored images of each color.

 The results are shown in Table 3.

Next, when the same fixing property test as in Example 1 was performed,
No image change was observed for any of the samples. Therefore, the image forming material of the present invention, it is possible to obtain a clear image corresponding to the coloring hue of each leuco dye,
Moreover, it is understood that reliable image storability (fixability) can be realized by simple dry heat treatment for each color.

Examples 11 to 14 The image forming materials shown below were prepared.

Sample (11): Leuco dye (leuco yellow dye) (4- [N-ethyl-N- {2-hydroxy-3-phenoxy-propyl} amino] -2-methylbenzylmalononitrile) carbanilate ester 1.5 parts p -Toluenesulfonic acid 0.6 part Photo-oxidizer 2,2'-bis- (o-chlorophenyl)-
4,4 ', 5,5'-Tetraphenylbiimidazole 3.0 parts Methylene chloride 12 parts Tricresyl phosphate 24 parts Takenate D-110N 24 parts were mixed, and the following were all applied in the same manner as sample (4). Paper was prepared and a sample (11) was obtained.

Sample (12): Sample (12) was prepared in the same manner as sample (11) except that p-dibutylaminophenyltricyanoethane: (leuco magenta dye) was used in place of the leuco yellow dye of sample (11). Got

Sample (13): Sample (11) except for using tris- (2-methyl-4-diethylamino-phenyl) methane: (leuco cyan dye) instead of the leuco yellow dye of sample (11). (13)
I got

Sample (14): 0.3 part of the leuco magenta dye and bis (2) instead of the leuco yellow dye of sample (11)
-Methyl-4-diethylaminophenyl) (4-diethylaminophenyl) methane: (leuco green dye) 1.
A sample (14) was obtained in the same manner as the sample (11) except that 4 parts were used.

Image exposure was performed on the above samples in the same manner as in Example 1 to obtain clear colored images of each color.

 The results are shown in Table 4.

Next, when the same fixing property test as in Example 1 was performed,
No image change was observed for any of the samples.

Comparative Examples 1 to 9 Photoimage forming materials shown below were prepared.

Sample (15): Leuco dye Leuco Crystal Violet 1.5 parts Photo-oxidizer 2,2'-bis- (o-chlorophenyl)
−4,4 ′, 5,5′-Tetraphenylbiimidazole 3.0 parts Methylene chloride 60 parts Isopropyl alcohol 8 parts Cellulose acetate butyrate (up to 27% butyryl content) 10 parts are mixed to form an organic solvent blend liquid. A sample (15) was obtained by preparing, coating and drying under the same conditions as the sample (1).

Sample (16): The mixture used for preparation of sample (15) contained 0.1 part of the following known antioxidant.

Hydroquinone (compound described in U.S. Pat. No. 3,042,515) Sample (17): The mixture used to prepare Sample (15) contained 0.1 part of the following known antioxidant.

1-phenylpyrazolidin-3-one (phenidone A) Sample (18): 0.1 part of the following known antioxidant was contained in the mixed solution used for preparation of sample (15).

2,4-dihydroxybenzaldoxime (JP-A-55-55,
Compound described in No. 335) Sample (19): The amount of 1-phenylpyrazolidin-3-one in the mixed solution of sample (17) was 6 parts. That is, the amount of the antioxidant (radical scavenger) was increased in the liquid mixture of the leuco dye and the photo-oxidizing agent.

Sample (20): A dispersion prepared by using hydroquinone instead of phenidone A of sample (1) was overcoated on the coated paper of sample (16).

Sample (21): A phenidone A dispersion obtained in the same manner as in sample (1) was overcoated on the coated paper of sample (17).

Sample (22): 6 parts of 1,2,3-triphenylguanidine were contained in the mixed solution used for preparation of sample (15).

Sample (23): The 1,2,3-triphenylguanidine dispersion prepared in Sample (4) was overcoated on the coated paper of Sample (17).

The above samples (15) to (23) and Examples 1, 4 and
Samples (1), (4), (7) to (1 used in 7 to 14
For 4), the following tests were conducted.

First, these coated papers were subjected to a dark reaction accelerating test under the conditions of a relative humidity of 75% and a temperature of 45 ° C., and the change with time due to discoloration of the unexposed sample was traced.

 Table 5 shows the results.

Samples (1), (4) and (7) to (14) of the present invention
It can be seen that, as compared with the Comparative Example, the raw sample has excellent raw storability due to the use of the capsule, and that the fresh sample is hardly colored.

Next, among the above-mentioned samples, a sample having 7 days elapsed (each number is marked with () ′) was subjected to image exposure in the same manner as in Example 1. The results are shown in Table 6.

Samples (1) ′, (4) ′, (7) ′ of the present invention
(14) ′ has low background color (background) in the unexposed area and has excellent image reproducibility (color density), whereas Comparative Samples (15) ′ to (23) ′ Is the background coloration or sensitivity deterioration over time (decrease in color density)
Is markedly inferior.

Further, in the same manner as in Example 1, a fixing test by passing through a heating roller was performed on each sample after image formation.

Table 7 shows the results of visual evaluation with respect to changes in the sample image after the second irradiation of the entire surface with light.

From the results of the above Examples and Comparative Examples, the image forming materials of the present invention (Samples (1), (4) and (7) to (14))
Has excellent raw storability, image reproducibility and image storability (fixability) as compared with Comparative Examples (Samples (15) to (23)). Further, it can be seen that it can be realized by a simple process, and that these materials have the advantages that they can be handled in an aqueous system at the time of application and that they are easy to handle and have excellent manufacturing suitability with safety.

Example 15 The following image forming material was prepared.

Samples (24) Were mixed and added to an aqueous solution consisting of 63 parts of an aqueous 8% by weight poly (vinyl alcohol) solution and 100 parts of distilled water, and then emulsified and dispersed at 20 ° C to obtain an emulsion having an average particle size of 1 µm. Furthermore, the obtained emulsion was continuously stirred at 40 ° C. for 3 hours. After that, the temperature was returned to room temperature and passed to obtain an aqueous capsule dispersion liquid.

Next, a polyvinyl alcohol 4% by weight aqueous solution 150 parts, a reducing agent 1-phenylpyrazolizone-3-one (phenidone A) 30 parts were mixed, and Dynomill (Willie A. Bakoven.
Dispersed by A.G. (trade name), average particle size 3
A μm phenidone A dispersion was obtained.

9 parts of the above capsule liquid and 6 parts of phenidone A dispersion liquid are mixed, and fine paper for super-calendering (basis weight 64 g / m ² ).
A solid coating amount of 10 g / m ² was applied to the sample and heated and dried at 50 ° C. for 1 minute to obtain a sample (24).

A sample (24-1) was obtained by heating this sample at several points at random at 100 ° C. for 1 second using a heat block. In addition, a test chart was recorded on the sample (24) by using a thermal head through NEC Nefax 3EX to obtain a sample (24-2).

The entire surface of each of these samples was irradiated with a jet light for 5 seconds to obtain a color image. The reflection densities in the visible region of the colored portion and the uncolored portion of each sample obtained as described above were measured with a Macbeth RD-918 type densitometer, and the results shown in Table 8 were obtained.

Next, these samples after image formation were passed through a heating roller at a temperature of 100 ° C. at a speed of 450 mm / min, and no image change was observed, and it was confirmed that they were fixed.

From the above results, the image forming material of the present invention can easily form a latent image of an image by heating, and can fix the image by subsequent irradiation of the entire surface, that is, it has excellent thermal recording characteristics. I understand.

Claims (3)

[Claims] 1. At least one selected from leuco dyes capable of oxidative coloring and at least one selected from photo-oxidizing agents are both encapsulated in microcapsules having a wall whose permeability to a substance increases by heating, and An image-forming material characterized in that at least one selected from a reducing agent is present outside the microcapsules. 2. At least one selected from leuco dyes capable of oxidative coloring and at least one selected from photo-oxidizing agents are both encapsulated in microcapsules having walls which increase the permeability of the substance by heating, and An image forming material characterized in that at least one selected from a reducing agent is present outside the microcapsules to form an image, and then the image forming material is heated to reduce the photooxidizing agent and the reducing agent. An image recording method, which comprises contacting an agent. 3. At least one selected from leuco dyes capable of oxidative coloring and at least one selected from photo-oxidizing agents are both encapsulated in microcapsules having a wall whose permeability to a substance increases by heating, and An image recording method comprising: exposing at least one kind selected from a reducing agent to the outside of the microcapsules to form an image latent image on the image forming material by heating, and then exposing the entire surface.