JPH0690491B2 - Positive image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Problems of Prior Art) Photothermographic materials are known in this technical field, and the photothermographic material and its process are described, for example, in "Basics of Photographic Engineering", non-silver photographic edition. 1982, published by Corona), pages 242 to 255, U.S. Pat. No. 4,500,626 and the like.

Many methods have been proposed for obtaining a positive image by heat development.

For example, in JP-A-61-159641 and JP-A-61-159643, an internal latent image type silver halide emulsion is subjected to image exposure, and then exposed to whole surface under heating or during heating to give a positive silver image or dye. A method for obtaining an image is described. But,
Since the method for forming a positive image by whole surface exposure is based on the formation of fog nuclei by photolysis of silver halide, the appropriate exposure illuminance and exposure amount differ depending on the type and characteristics of the silver halide used. Therefore, it is difficult to obtain a constant performance, and the developing device is complicated and expensive. There is also a drawback that the development time is long.

In JP-A-61-107243, a photothermographic material containing an internal latent image type silver halide emulsion, an organic silver salt oxidizing agent, a nucleating agent and a base precursor is imagewise exposed and heated to form a positive image. How to do is described. However, it is difficult to obtain sufficient raw storage stability by using a photothermographic material having such a composition.

Further, there are those obtained by a heat-sensitive silver dye bleaching method, those using a nitroxyl compound, those using a dye developing agent, those using an oxidized dye-donating substance, those using a reduced dye-donating substance, etc. There are drawbacks such as high fog density of the positive image thus obtained and relatively long development time.

(Object of the Invention) The present invention provides a method for obtaining a constant high-quality positive image having sufficient image density and low fog in a short developing time without requiring a complicated and expensive developing device. With the goal.

(Constitution of the Invention) The object of the present invention is to provide a photosensitive element containing at least an internal latent image type silver halide emulsion, a reducing agent and / or a precursor thereof and a compound represented by the following general formula [I] on a support. Was developed by a positive image forming method.

General formula [I] In the formula, Z ¹ represents a nonmetallic atom group necessary for forming a 5- or 6-membered heterocycle. An aromatic ring or a heterocycle may be further condensed with this heterocycle.

R ¹ is an aliphatic group, Is. Q represents a 4- to 12-membered non-aromatic hydrocarbon ring or a non-metal atom group necessary for forming a non-aromatic heterocycle. However, at least one of the substituents of R ¹ and Z ^{1 and} the substituent of Q includes an alkynyl group. Further, at least one of R ¹ , Z ¹ , and Q may have an adsorption promoting group on silver halide, Y is a counter ion for charge balance, and n is for charge balance. It is the required number.

The nucleating agent represented by the general formula [I] will be described in more detail. Examples of the heterocycle completed by Z ¹ include quinolinium, benzimidazolium, pyridinium, thiazolium, selenazolium, imidazolium, tetrazolium, indolenium, pyrrolinium. , Acridinium, phenanthridinium, isoquinolinium, and naphthopyridinium nuclei. Z ¹ may be substituted with a substituent, and as the substituent, an alkyl group, an alkenyl group, an aralkyl group, an aryl group, an alkynyl group, a hydroxy group, an alkoxy group, an aryloxy group,
Halogen atom, amino group, alkylthio group, arylthio group, acyloxy group, acylamino group, sulfonyl group, sulfonyloxy group, sulfonylamino group, carboxyl group, acyl group, carbamoyl group, sulfamoyl group, sulfo group, cyano group, ureido group, Examples thereof include urethane group, carbonic acid ester group, hydrazine group, hydrazone group, and imino group. As the substituent of Z ¹ , for example, at least one is selected from the above-mentioned substituents, but when there are two or more, they may be the same or different. Further, the above substituents may be further substituted with these substituents.

Further, it may have a heterocyclic quaternary ammonium group completed with Z ¹ via a suitable linking group L ¹ as a substituent of Z ¹ . In this case, a so-called dimer structure is adopted.

The heterocyclic bone nucleus completed with Z ¹ is preferably a quinolinium, benzimidazolium, pyridinium, acridinium, phenanthridinium, naphthopyridinium or isoquinolinium nucleus. More preferably,
It is a quinolinium, naphthopyridinium or benzimidazolium nucleus, most preferably a quinolinium nucleus.

The aliphatic group represented by R ¹ is preferably an unsubstituted alkyl group having 1 to 18 carbon atoms and a substituted alkyl group having 1 to 18 carbon atoms in the alkyl moiety. Examples of the substituent include those described as the substituent for Z ¹ .

R ¹ is preferably an alkynyl group, and most preferably a propargyl group.

Q is a group of atoms necessary for forming a 4- to 12-membered non-aromatic hydrocarbon ring or non-aromatic heterocycle. These rings are Z ¹
It may be further substituted with the group described for the substituent.

As the non-aromatic hydrocarbon ring, when X is a carbon atom, examples thereof include rings such as cyclopentane, cyclohexane, cyclohexene, cycloheptane, indane and tetralin.

The non-aromatic heterocycle includes nitrogen, oxygen, sulfur, selenium and the like as a hetero atom, and is, for example, X
When is a carbon atom, examples thereof include rings such as tetrahydrofuran, tetrahydropyran, butyrolactone, pyrrolidone, and tetrahydrothiophene. When X is a nitrogen atom, examples thereof include rings such as pyrrolidine, piperidine, pyridone, piperazine, perhydrothiazine, tetrahydroquinoline and indoline.

Preferred as the ring nucleus formed by Q is when X is a carbon atom, particularly cyclopentane, cyclohexane,
Cycloheptane, cyclohexene, indane, tetrahydropyran, tetrahydrothiophene and the like.

As the alkynyl group to which at least one of the substituents of R ¹ and Z ^{1 and} the substituent of Q corresponds, some have already been described so far, but when explained in more detail, preferably, the number of carbon atoms is 2 to There are 18 groups such as thienyl group, propargyl group, 2-butynyl group, 1-methylpropargyl group, 1,1-dimethylpropargyl group, 3-butynyl group and 4-pentynyl group.

Further, these may be substituted with the groups described as the substituent for Z ¹ .

The alkynyl group is preferably a propargyl group, and most preferably R ¹ is a propargyl group.

As the adsorption promoting group to silver halide which the substituents of R ¹ , Q and Z ¹ may have, those represented by X ¹ L ¹ _m are preferable.

Here, X ¹ is an adsorption promoting group to silver halide, and L ¹ is a divalent linking group. m is 0 or 1. Preferred examples of the adsorption promoting group for silver halide represented by X ¹ include
Examples thereof include a thioamide group, a mercapto group and a 5- or 6-membered nitrogen-containing heterocyclic group.

These may be substituted with those mentioned as the substituent of Z ¹ . The thioamide group is preferably an acyclic thioamide group (eg, thiourethane group, thioureido group, etc.)
Is.

As the mercapto group of X ¹ , particularly a heterocyclic mercapto group (for example, 5-mercaptotetrazole, 3-mercapto-1,2,4-triazole), 2-mercapto-1,3,4-thiadiazole, 2-mercapto-1 3,3,4-oxadiazole and the like) are preferred.

The 5- or 6-membered nitrogen-containing heterocycle represented by X ¹ is
It is composed of a combination of nitrogen, oxygen, sulfur and carbon, and preferably forms imino silver, and examples thereof include benzotriazole and aminothiatriazole.

Examples of the divalent linking group represented by L ¹ include C, N, S and O.
An atom or atomic group containing at least one of the above. Specifically, for example, an alkylene group, an alkenylene group, an alkynylene group, an arylene group —O—, —S—, —NH—, —
N =, —CO—, —SO ₂ — (these groups may have a substituent), etc., alone or in combination.

As an example of the combination, -SO ₂ NH-, -NHSO ₂ NH-, - (arylene) -SO ₂ NH-, Are preferred.

Examples of the counter ion Y for charge balance include bromine ion, chlorine ion, iodine ion, p-toluenesulfonate ion, ethylsulfonate ion, perchlorate ion, trifluoromethanesulfonate ion, thiocyanate BF ₄ −. Ions, PF ₆ − ions and the like.

Of the compounds represented by the general formula [I], those having an adsorption promoting group on silver halide are preferable, and particularly, the adsorption promoting group X ¹ may be a thioamide group, an azole group or a heterocyclic mercapto group. More preferable.

Examples of these compounds and their synthesis methods are described in, for example, Japanese Patent Application No.
-17,984 and the patents or literature cited therein.

Specific examples of the compound represented by the general formula [I] are shown below, but the present invention is not limited thereto.

In the present invention, when a compound represented by the general formula [I] is contained in a photographic light-sensitive material, water such as alcohols (eg methanol, ethanol), esters (eg ethyl acetate), ketones (eg acetone), etc. It may be added to the hydrophilic colloid solution as a solution of an organic solvent that is miscible with, or as an aqueous solution when it is water-soluble.

When it is added to the photographic emulsion, it may be added at any time from the start of chemical ripening to before coating, but it is preferably added after the completion of chemical ripening.

In the present invention, the nucleating agent represented by the general formula [I] may be contained in the hydrophilic colloid layer adjacent to the silver halide emulsion layer, but is preferably contained in the silver halide emulsion layer. The amount added varies depending on the characteristics of the silver halide emulsion actually used, the chemical structure of the nucleating agent and the developing conditions, and therefore can vary over a wide range. About 1 × 10 ^-8 moles to about 1 × 10
A range of ^-2 mol is practically useful, with about 1 x 10 ^-7 to about 1 x 10 ^-3 mol per mol silver being preferred.

The light-sensitive element used in the present invention contains an internal latent image type silver halide emulsion.

In contrast to conventional chemically sensitized silver halide grains which preferentially form a latent image on the surface, internal latent image type silver halide emulsions preferentially form a latent image within the silver halide grains.

In general, an internal latent image type silver halide emulsion is prepared by coating a standard amount of an emulsion on a transparent support and exposing it for a certain period of time within the range of 1 × 10 ^-2 to 1 second. All) When using a developer Y which is a latent image developer for about 5 minutes to develop at 18 ° C. and test by the standard photographic test method, the same exposure is performed,
20 minutes in developer X, which is the developer for surface latent image below,
It gives a maximum density (Dmax) of at least 5 times that of the same sample developed at ° C.

Preferably, the Dmax in developer Y is at least 0.5 density unit greater than the Dmax in developer X, and / or the grains of the emulsion have a ratio of total sensitivity to surface sensitivity of 5%.
It should be more than twice.

Developer X N-methyl-p-aminophenol sulphate 25.0 g Ascorbic acid 10.0 g Potassium metaborate 35.0 g Potassium bromide 1.0 g Water added 1 pH 9.5 Developer Y N-methyl-p-aminophenol sulphate 2.0 g Dry sodium sulphate 90.0g Hydroquinone 8.0g Sodium carbonate monohydrate 52.5g Potassium bromide 5.0g Potassium iodide 0.5g Add water 1 Internal latent image type silver halide emulsions such as silver chloride Convergence emulsions obtained by a method of converting highly soluble silver salt grains into a less soluble silver salt such as (iodo) silver bromide (Kyatastrophi precipitation method) (for example, US Pat. No. 2,592,250). ), A core / shell emulsion in which silver halide shells are coated on core grains by a method of mixing fine grain emulsions with chemically sensitized large grain core emulsions and ripening (for example, US Pat. No. 3,206,313). , A core in which a silver halide shell is coated on a core grain by a method in which a soluble silver salt solution and a soluble halide solution are simultaneously added to a chemically sensitized monodisperse core emulsion while maintaining a constant silver ion concentration. Shell emulsions (eg British Patent 1,027,146
, U.S. Pat. No. 3,761,276), core / shell emulsion in which silver halide is coated by depositing silver halide on silver halide core grains doped with metal ions inside the grains, and emulsion grains are 2 A halogen-localized emulsion having a laminated structure of three or more and different halogen compositions from the first phase and the second phase (for example, US Pat. No. 3,935,014), 3
Emulsions containing dissimilar metals incorporated by forming silver halide grains in an acidic medium containing valent metal ions (US Pat. No. 3,44,44).
No. 7,927). Others, Photographic Emulsio by EJ Wall
n) 35-36, 52-53, American Photographic Publi
shing Co., (1929), and US Pat. No. 2,497,875
No., No. 2,563,785, No. 3,511,662, No. 4,395,47
No. 8 and West German Patent Publication (OLS) No. 2,728,108, etc. are also included.

Of the above-mentioned internal latent image type emulsions, the core / shell type emulsions as described above are particularly preferable for the application of the present invention.

That is, the preferred surface chemically sensitized internal latent image type silver halide emulsion of the present invention is doped with metal ions or
An inner core (core grain) of silver halide chemically sensitized or both was prepared, and then its surface was coated with an outer shell (shell) of silver halide and then with an outer shell. The surface of silver halide grains is optimally chemically sensitized.

Optimum surface chemical sensitization here means Dmax of inverted image, Dmin of inverted image, sensitivity of inverted image, and re-inverted image (negative image).
It means to chemically sensitize so that the sensitivity of is kept in the best balance.

The method of doping the inner nucleus of silver halide with a metal ion is, for example, in the process of forming silver halide grains or physically ripening the inner nucleus, cadmium salt, zinc salt, lead salt, thallium salt, erbium salt, bismuth salt, iridium. A method of coexisting a metal ion source such as a salt or a complex salt thereof, a rhodium salt, a complex salt thereof, an iron salt or a complex salt thereof can be adopted.

The metal ion is usually used in a ratio of 10 ^-6 mol or more per 1 mol of silver halide.

Further, the silver halide grains in the inner core may be chemically sensitized without doping with the above metal ions or together with the dope using at least one of a noble metal sensitizer, a sulfur sensitizer and a reduction sensitizer. . In particular, when gold / sulfur sensitization was performed on the surface of the silver halide grain of the inner core and then the outer shell was covered, the surface / chemically sensitized core / shell type silver halide grain was prepared. Is obtained.

The use ratio of the silver halide of the inner core and the silver halide of the outer shell is arbitrary, but the outer shell may cover at least the photosensitive site of the inner core (the site that produces photolytic silver upon exposure), Normally, for 1 mol of silver halide in the inner nucleus,
For the outer shell, 0.1 to 10 mol (preferably 1 to 8 mol) is used.

The silver halides of the inner core and the outer shell preferably have the same composition, but may have different compositions.

As each silver halide, for example, silver bromide, silver iodide, silver chloride, silver chlorobromide, silver iodobromide, silver chlorobromoiodide, and the like can be used, but a preferable silver halide emulsion is at least 50
%, And most preferred emulsions are silver bromide and silver bromoiodide (especially those containing 10 mol% or less of silver iodide).

In the present invention, core / shell type silver halide grains having various grain sizes can be used, but the average grain diameter is
0.1-4 micron, preferably 0.2-3 millilon core /
Shell-type silver halide grains give good results.

The core / shell type silver halide grains may have regular crystal bodies such as cubes and octahedra,
In addition, those having irregular crystal forms such as spheres and plates, those having a composite form of these crystal forms, and those consisting of a mixture of particles of various crystal forms Good. As the plate-like particles, those having an aspect ratio of 5 or more, especially 8 or more can be used (for example, those described in JP-A-58-108528).

The surface chemical sensitization includes a sulfur sensitization method using a compound containing sulfur capable of reacting with silver ions or active gelatin, a reduction sensitization method using a reducing substance, a noble metal compound method using gold or other noble metal compounds, or a combination thereof. Can be done.

Although various conditions in the chemical sensitization step may be arbitrarily determined, it is preferable that the general formula is performed at pH 9 or higher, pAg 11 or lower, and temperature 50 ° C. or higher. However, in some cases, conditions may be set outside this range.

Examples of the reducing substance used in the reduction sensitization method include a primary tin salt, an amine salt, a hydrazine derivative, formamidine sulfinic acid, and a silane compound. Also,
Noble metal compounds include Pt, Ir, Pd, etc.
There are complex salts of group metals.

Of the above-mentioned chemical sensitization methods, the method which gives the most reversal performance is the sulfur sensitization method using a sulfur sensitizer, and the sulfur sensitization is carried out in the presence of a polymer such as the poly (N-vinylpyrrolidone). Is performed, a better reversal performance is obtained.
In some cases, a sulfur sensitizer and a gold complex salt may be used in combination.

Examples of the sulfur sensitizer include compounds such as thiosulfates, thioureas, thiazoles, and rhodanines, and specific examples thereof are U.S. Pat.Nos. 1,574,944, 2,410,689, and
2,278,947, 2,728,668, 3,656,955, and JP-A-55-45016.

The coating amount of the internal latent image type silver halide emulsion used in the present invention is in the range of 0.01 to 5 g / m ² in terms of silver per layer.

The silver halide used in the present invention may be spectrally sensitized with methine dyes or the like. The dyes used include cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, holopolar cyanine dyes, hemicyanine dyes, styryl dyes and hemioxonol dyes.

Specifically, sensitizing dyes described in JP-A Nos. 59-180550 and 60-140335, Research Disclosure June 1978, pages 12 to 13 (RD17029), and JP-A-60- −111239
And heat-decolorizing sensitizing dyes described in Japanese Patent Application No. 60-172967.

These sensitizing dyes may be used alone or in combination thereof, and the combination of sensitizing dyes is often used especially for the purpose of supersensitization.

A dye that does not have a spectral sensitizing effect by itself, or a substance that does not substantially absorb visible light, together with a sensitizing dye,
A substance exhibiting supersensitization may be contained in the emulsion (for example, U.S. Pat.Nos. 2,933,390, 3,635,721, 3,743,510,
No. 3,615,613, No. 3,615,641, No. 3,617,295, No. 3,6
No. 35,721).

These sensitizing dyes may be added to the emulsion at the time of chemical ripening or before or after chemical ripening, and U.S. Pat.
No. 4,225,666, before or after nucleation of silver halide grains.

The addition amount is generally 10 ^-8 to 10 per mol of silver halide.
^-It is about ² mol.

The heat-developable photosensitive element of the present invention basically has a photosensitive silver halide and a binder on a support, and, if necessary, an organometallic salt oxidizing agent, a dye-donating compound (as described later). (A reducing agent may also serve) and the like. These components are often added to the same layer, but if they are in a reactive state, they can be divided and added to separate layers. For example, when a colored dye-donor compound is present in the lower layer of the silver halide emulsion, the reduction in sensitivity can be prevented. The reducing agent is preferably incorporated in the photothermographic element, but it may be supplied from the outside by, for example, a method of diffusing from a dye fixing element described later.

In order to obtain a wide range of colors in the chromaticity diagram by using the three primary colors of yellow, magenta, and cyan, a combination of at least three silver halide emulsion layers having photosensitivity in different spectral regions is used. For example, there are combinations of three layers of a blue-sensitive layer, a green-sensitive layer and a red-sensitive layer, a combination of a green-sensitive layer, a red-sensitive layer and an infrared-sensitive layer. Each light-sensitive layer can be colored in various arrangement sequences known in a conventional type color light-sensitive material. Further, each of these photosensitive layers may be divided into two or more layers if necessary.

The heat-developable photosensitive element can be provided with various auxiliary layers such as a protective layer, an undercoat layer, an intermediate layer, a yellow filter layer, an antihalation layer and a back layer.

In the present invention, an organic metal salt may be used as an oxidizing agent together with the photosensitive silver halide. Among such organic metal salts, organic silver salts are particularly preferably used.

Organic compounds that can be used to form the above organic silver salt oxidizing agent include benzotriazoles, fatty acids and other compounds described in US Pat. No. 4,500,626, columns 52 to 53. Further, silver salts of carboxylic acid having an alkynyl group such as silver phenylpropiolic acid described in JP-A-60-113235 and acetylene silver described in JP-A-61-290444 are also useful. Two or more kinds of organic silver salts may be used in combination.

The above organic silver salts are the following per mol of photosensitive silver halide:
0.01 to 10 mol, preferably 0.01 to 1 mol can be used in combination. The total coating amount of the photosensitive silver halide and the organic silver salt is preferably 50 mg to 10 g / m ² in terms of silver.

Various antifoggants or photographic stabilizers can be used in the present invention. For example, RD17643 (1
978) azoles and azaindenes described on pages 24 to 25, nitrogen-containing carboxylic acids and phosphoric acids described in JP-A-59-168442, or mercapto compounds and metal salts thereof described in JP-A-59-111636. The acetylene compounds described in JP-A-62-87957 are used.

As the reducing agent used in the present invention, those known in the field of photothermographic materials can be used. Further, a dye-donor compound having a reducing property described later is also included (in this case, other reducing agents can be used together). Further, a reducing agent precursor which has no reducing property itself but exhibits reducing property by the action of a nucleophile or heat during the development process can also be used.

Examples of the reducing agent used in the present invention include U.S. Pat.
Columns 49-50 of 500,626, 30-31 of 4,483,914
Column, No. 4,330,617, No. 4,590,152, JP-A-60-14
0335, pages (17)-(18), 57-40245, 56-1.
38736, 59-178458, 59-53831, 59-1824
No. 49, No. 59-182450, No. 60-119555, No. 60-128436
No. 60-128439, No. 60-198540, No. 60-18
1742, 61-259253, 62-244044, 62-1312
From 53 to 62-131256, there are reducing agents and reducing agent precursors described in European Patent No. 220,746A2, pages 78 to 96, and the like.

Combinations of various reducing agents such as those disclosed in US Pat. No. 3,039,869 can also be used.

When a diffusion resistant reducing agent is used, an electron transfer agent and / or an electron transfer agent may be added, if necessary, in order to promote electron transfer between the diffusion resistant reducing agent and the developable silver halide. A combination of precursors can be used.

The electron transfer agent or its precursor can be selected from the above-mentioned reducing agent or its precursor. It is desirable that the electron transfer agent or its precursor has a mobility higher than that of the diffusion resistant reducing agent (electron donor).
Particularly useful electron transfer agents are 1-phenyl-3-pyrazolidones or aminophenols.

The diffusion-resistant reducing agent (electron donor) used in combination with the electron transfer agent may be one that does not substantially move in the layer of the photosensitive element among the reducing agents described above, and preferably hydroquinone, Examples thereof include sulfonamide phenols, sulfonamide naphthols, compounds described as electron donors in JP-A-53-110827, and dye-donating compounds having diffusion resistance and reducing properties described later.

In the present invention, the amount of reducing agent added is 0.
The amount is 01 to 20 mol, particularly preferably 0.1 to 10 mol.

In the present invention, silver can be used as the image forming substance. Further, when the silver ion is reduced to silver under a high temperature condition, a compound which generates or releases a mobile dye corresponding to this reaction, that is, a dye-donor compound can be contained.

Examples of the dye-donating compound that can be used in the present invention include compounds (couplers) that form a dye by an oxidative coupling reaction. The coupler may be a 4-equivalent coupler or a 2-equivalent coupler. Also,
A 2-equivalent coupler having a nondiffusible group as a leaving group and forming a diffusible dye by an oxidative coupling reaction is also preferable. The diffusion resistant group may form a polymer chain. Specific examples of color development and couplers can be found in "The Theory of the Photographic Proces", 4th edition, "The Theory of the Photographic Process" by James.
s ") pages 291-334 and 354-361, JP-A-58-123533.
No. 58-149046, No. 58-149047, No. 59-111148
No. 59, No. 59-124399, No. 59-174835, No. 59-231539
No., No. 59-231540, No. 60-2950, No. 60-2951 and No.
60-14242, 60-23474, 60-66249 and the like.

As another example of the dye-donating compound, a compound having a function of releasing or diffusing a diffusible dye in an image form can be mentioned. This type of compound can be represented by the following general formula [L1].

(Dye-Y) _n -Z [L1] Dye represents a dye group, a temporarily shortened dye group or a dye precursor group, Y represents a simple bond or linking group, and Z represents an image latent image. Or (Dye-Y) _n- Z causes a difference in the diffusivity of the compound represented by (Dye-Y) _n -Z corresponding to the photosensitive silver salt having
Y) _n- Z represents a group having a property of causing a difference in diffusibility between _{n and} Z, n represents 1 or 2, and n
Is 2, the two Dye-Ys may be the same or different.

Specific examples of the dye-donating compound represented by the general formula [LI] include the following compounds (1) to (3).

A compound which has a diffusible dye as a leaving group and releases the diffusible dye by reacting with an oxidant of a reducing agent (DD
R coupler). Specifically, British Patent No. 1,330,524, Japanese Patent Publication No. 48-39,165, U.S. Patent Nos. 3,443,940, and 4,47.
4,867 and 4,483,914.

Reducible to silver halide or organic silver salt,
A compound that releases a diffusible dye when its partner is reduced (DRR
Compound). Since this compound does not need to use another reducing agent, it is preferable because there is no problem of image contamination due to oxidative decomposition products of the reducing agent. A typical example is U.S. Pat. No. 3,928,312.
No. 4,053,312, No. 4,055,428, No. 4,336,32
2, JP-A-59-65839, JP-A-59-69839, JP-A-53-3819
No. 51-104,343, RD17465, U.S. Pat.No. 3,725,06.
No. 2, No. 3,728,113, No. 3,443,939, JP-A-58-1
16,537, 57-179840, US Pat. No. 4,500,626 and the like. Specific examples of the DRR compound include the compounds described in the above-mentioned U.S. Pat. No. 4,500,626 in columns 22 to 44. Among them, the compounds (1) to (3) described in the above-mentioned U.S. Pat. (10) ~ (13), (16) ~
(19), (28) ~ (30), (33) ~ (35), (38) ~
(40) and (42) to (64) are preferable. Also U.S. Pat.
The compounds described in 639,408, columns 37 to 39 are also useful.

In addition, as a dye-donor compound other than the coupler and the general formula [LI] described above, a dye silver compound in which an organic silver salt and a dye are bonded (Research Disclosure, May 1978, pages 54 to 58, etc.) ), Azo dyes used in the heat developable silver dye bleaching method (U.S. Pat.No. 4,235,957, Research Disclosure magazine, April 1976, pages 30 to 32), leuco dyes (U.S. Pat. 4,022,617 etc.) can also be used.

Hydrophobic additives such as dye-donor compounds and diffusion resistant reducing agents can be incorporated into the layers of the light-sensitive element by known methods such as the method described in US Pat. No. 2,322,027. In this case, JP-A-59-83154, 59-178451 and 59-1
78452, 59-178453, 59-178454, 59-178
High boiling point organic solvents such as those described in Nos. 455 and 59-178457 can be used in combination with a low boiling point organic solvent having a boiling point of 50 ° C. to 160 ° C., if necessary.

The amount of the high boiling point organic solvent is 10 g or less, preferably 5 g or less, relative to 1 g of the dye-donor compound used. Also, 1 cc or less per 1 g of binder, 0.5 cc or less, especially 0.3 c
c or less is appropriate.

The dispersion method using a polymer described in JP-B-51-39853 and JP-A-51-59943 can also be used.

In the case of a compound which is substantially insoluble in water, fine particles can be dispersed and contained in a binder in addition to the above method.

When dispersing the hydrophobic compound in the hydrophilic colloid, various surfactants can be used. For example, JP-A-59-
The surfactants listed on pages (37) to (38) of 157636 can be used.

In the present invention, a compound capable of activating development and stabilizing an image at the same time can be used in the light-sensitive element. For specific compounds that are preferably used, see US Pat.
No. 6 columns 51-52.

Dye-fixing elements are used with light-sensitive elements in systems that form images by diffusion transfer of dyes. The dye-fixing element may be applied separately on a support different from the photosensitive element, or may be applied on the same support as the photosensitive element. Regarding the relationship between the light-sensitive element and the dye-fixing element, the relationship with the support, and the relationship with the white reflective layer, the relationship described in column 57 of US Pat. No. 4,500,626 can be applied to the present application.

The dye fixing element preferably used in the present invention has at least one layer containing a mordant and a binder. As the mordant, one known in the photographic field can be used, and specific examples thereof include U.S. Pat. No. 4,500,626, columns 58 to 59 and JP-A-61-18.
8256, mordanting agents described on pages (32) to (41), JP-A-62-
Examples thereof include those described in Nos. 244043 and 62-244036. Further, a dye-receptive polymer compound as described in US Pat. No. 4,463,079 may be used.

If necessary, the dye fixing element can be provided with auxiliary layers such as a protective layer, a peeling layer and an anti-curl layer. In particular, it is useful to provide a protective layer.

A hydrophilic binder is preferably used as the binder of the constituent layers of the light-sensitive element and the dye fixing element. As an example,
Examples are those described on pages (26) to (28) of No. 62-253159. Specifically, a transparent or translucent hydrophilic binder is preferable, and for example, gelatin or a protein or cellulose derivative such as a gelatin derivative, starch, gum arabic, dextran, a natural compound such as a polysaccharide such as pullulan, and polyvinyl alcohol, Examples thereof include polyvinylpyrrolidone, acrylamide polymer, and other synthetic polymer compounds. Furthermore, superabsorbent polymers described in JP-A-62-245260, i.e. -COOM or -SO ₃ M (M
Is a homopolymer of a vinyl monomer having a hydrogen atom or an alkali metal or a copolymer of the vinyl monomers with each other or with another vinyl monomer (for example, sodium methacrylate, ammonium methacrylate, Sumika Gel L- manufactured by Sumitomo Chemical Co., Ltd.). 5H) is also used. These binders can be used in combination of two or more.

When employing a system in which a small amount of water is supplied for thermal development, the use of the superabsorbent polymer makes it possible to quickly absorb water. Also, the use of superabsorbent polymers in the dye-fixing layer or its protective layer can prevent the dye from retransferring from the dye-fixing element to another after transfer.

In the present invention, the coating amount of the binder is 20 g per 1 m ^2.
The amount is preferably the following, particularly 10 g or less, and more preferably 7 g or less.

The hardener used for the constituent layers of the light-sensitive element and the dye-fixing element is described in U.S. Pat. No. 4,678,739, column 41, JP-A-59-116655.
No. 62-245261, No. 61-18942, and the like. More specifically, aldehyde type hardener (formaldehyde etc.), aziridine type hardener, epoxy type hardener Vinyl sulfone type hardeners (N, N'-ethylene-bis (vinylsulfonylacetamide) ethane, etc.), N-methylol type hardeners (dimethylol urea, etc.), or polymer hardeners (JP-A-62) -234157 and the like).

In the present invention, an image formation accelerator can be used in the light-sensitive element and / or the dye fixing element. The image formation accelerator includes a redox reaction between a silver salt oxidizing agent and a reducing agent, a reaction such as generation of a dye from a dye-donor substance, decomposition of the dye or release of a diffusible dye, and a light-sensitive material layer. Has a function of accelerating the transfer of the dye from the dye to the dye fixing layer, and from the physicochemical function, a base or a base precursor, a nucleophilic compound, a high boiling organic solvent (oil), a thermal solvent, a surfactant, silver Alternatively, they are classified into compounds that interact with silver ions. However, these substance groups generally have a composite function, and usually have some of the above-mentioned accelerating effects together. For more information on these, see US Pat.
No. 38 to 40 columns.

Examples of the base precursor include salts of an organic acid and a base that are decarboxylated by heat, a compound that releases amines by an intramolecular nucleophilic substitution reaction, a Rotsen rearrangement or a Beckmann rearrangement. Specific examples thereof are U.S. Pat. No. 4,511,493 and JP-A-62-6.
No. 5038, etc.

In a system in which heat development and transfer of a dye are simultaneously performed in the presence of a small amount of water, it is preferable to add a base and / or a base precursor to the dye-fixing element in order to enhance the storage stability of the light-sensitive element.

In addition to the above, a combination of a sparingly soluble metal compound described in European Patent Publication No. 210,660 and a compound capable of complex-forming reaction with a metal ion constituting the sparingly soluble metal compound (referred to as a complex-forming compound), and JP-A- The compounds that generate a base by electrolysis as described in 61-232451 can also be used as the base precursor. The former method is particularly effective. The sparingly soluble metal compound and the complex-forming compound are advantageously added separately to the light-sensitive element and the dye-fixing element.

In the light-sensitive element and / or the dye-fixing element of the present invention, various development terminators can be used for the purpose of always obtaining a constant image against variations in processing temperature and processing time during development.

The term "development terminating agent" as used herein refers to a compound that immediately neutralizes or reacts with a base to reduce the concentration of the base in the film to stop the development after proper development, or inhibits development by interacting with silver and a silver salt. Compound. Specific examples thereof include an acid precursor that releases an acid when heated, an electrophilic compound that causes a substitution reaction with a coexisting base when heated, or a nitrogen-containing heterocyclic compound, a mercapto compound and a precursor thereof. Further details are described in JP-A-62-253159, pages (31) to (32).

The constituent layers (including the backing layer) of the light-sensitive element or the dye-fixing element include various polymers for the purpose of improving physical properties of the film such as dimensional stability, curl prevention, adhesion prevention, film cracking prevention, and pressure increase / decrease prevention. A lattex may be included. Specifically, JP-A 62-245258, 62-136648, and 62
Any of the polymer latexes described in -110066 and the like can be used. In particular, when polymer latex with a low glass transition point (40 ° C or less) is used for the mordant layer, cracking of the mordant layer can be prevented, and when polymer latex with a high glass transition point is used for the back layer, curl is prevented. The effect is obtained.

In the constituent layers of the light-sensitive element and the dye-fixing element, a high-boiling organic solvent can be used as a plasticizer, a slipping agent, or a peelability improver for the light-sensitive element and the dye-fixing element. Specific examples include those described in JP-A-62-253159, page (25), JP-A-62-245253, and the like.

Further, various silicone oils (all silicone oils from dimethyl silicone oils to modified silicone oils obtained by introducing various organic groups into dimethyl siloxane) can be used for the above purpose. Examples include various modified silicone oils described in "Modified Silicone Oil" technical material P6-18B issued by Shin-Etsu Silicone Co., Ltd., especially carboxy-modified silicone (trade name X-22-37.
10) etc. are effective.

Further, the silicone oils described in JP-A No. 62-215953 and Japanese Patent Application No. 62-23687 are also effective.

An anti-fading agent may be used in the light-sensitive element and the dye fixing element. As the anti-fading agent, there are, for example, an antioxidant, an ultraviolet absorber, or a kind of metal complex.

Examples of the antioxidant include chroman compounds, coumarane compounds, phenol compounds (for example, hindered phenols), hydroquinone derivatives, hindered amine derivatives, and spiroindane compounds. The compounds described in JP-A No. 61-159644 are also effective.

Examples of UV absorbers include benzotriazole compounds (US Pat. No. 3,533,794, etc.), 4-thiazolidone compounds (US Pat. No. 3,352681, etc.), benzophenone compounds (JP-A-46-2784, etc.), and others. JP 54-
There are compounds described in 48535, 62-136641, 61-88256 and the like. Further, the ultraviolet absorbing polymer described in JP-A-62-260152 is also effective.

Examples of the metal complex include U.S. Patent Nos. 4,241,155 and 4,24.
No. 5,018, columns 3 to 36, No. 4,254,195, columns 3 to 8, JP-A Nos. 50-87649, 62-174741, 61-88256 (27).
To (29), Japanese Patent Application Nos. 62-234103, 62-31096, and Japanese Patent Application No. 62-230596.

Examples of useful anti-fading agents include JP-A-62-215272 (125)
See page (137).

The anti-fading agent for preventing the fading of the dye transferred to the dye-fixing element may be contained in the dye-fixing element in advance, or may be supplied to the dye-fixing element from the outside such as a light-sensitive element. .

The above-mentioned antioxidant, ultraviolet absorber, and metal complex may be used in combination.

A fluorescent whitening agent may be used in the light-sensitive element and the dye-fixing element. In particular, it is preferable that the dye-fixing element contains a fluorescent whitening agent or is supplied from the outside of the light-sensitive element. For example, see “Thr Chemistry of Synt” edited by K. Veenkataraman.
"Hetic Dyes", Volume V, Chapter 8, and compounds described in JP-A-61-143752 and the like. More specifically, stilbene compounds, coumarin compounds, biphenyl compounds, benzoxazolyl compounds, naphthalimide compounds, pyrazoline compounds, carbostyryl compounds and the like can be mentioned.

The fluorescent whitening agent can be used in combination with an anti-fading agent.

In the constituent layers of the light-sensitive element and the dye-fixing element, various surfactants can be used for the purpose of coating aid, improvement of peeling property, improvement of sliding property, antistatic property, acceleration of development and the like. Specific examples of the surfactant are described in JP-A-62-173463 and JP-A-62-183457.

In the constituent layers of the light-sensitive element and the dye-fixing element, the slip property is improved,
An organic fluoro compound may be included for the purpose of preventing static electricity, improving peelability and the like. As typical examples of organic fluoro compounds, JP-B-57-9053, columns 8 to 17, JP-A-61-20944 can be used.
No. 62-135826, etc., or fluorine-containing compounds such as fluorine-containing compounds such as fluorine-containing surfactants or solid fluorine-containing compounds such as tetrafluoroethylene resin. Examples include elementary compounds.

A matting agent can be used for the light-sensitive element and the dye fixing element. Examples of matting agents include silicon dioxide, polyolefin and polymethacrylate. JP-A-61-88256 (2
In addition to the compounds described in page 9), there are compounds described in Japanese Patent Application Nos. 62-110064 and 62-110065, such as benzoguanamine resin beads, polycarbonate resin beads, and AS resin beads.

In addition, the constituent layers of the light-sensitive element and the dye-fixing element may contain a thermal solvent, a defoaming agent, an antibacterial / antifungal agent, colloidal silica and the like. Specific examples of these additives are described in Japanese Patent Application No. 61-88.
No. 256, pages (26) to (32).

As the support for the light-sensitive element and the dye-fixing element of the present invention, those which can withstand the processing temperature are used. Generally, paper and synthetic polymer (film) are used. Specifically, polyethylene terephthalate, polycarbonate, polyvinyl chloride, polystyrene, polypropylene,
Polyimide, celluloses (for example, triacetyl cellulose) or those films containing pigments such as titanium oxide, synthetic film made of polypropylene and the like, synthetic resin such as polyethylene, and synthetic pulp and natural pulp. Mixed papers, Yankee papers, baryta papers, coated papers (particularly cast coated papers), metals, cloths, glasses and the like are used.

These can be used alone or as a support having one or both sides laminated with a synthetic polymer such as polyethylene.

In addition, the supports described in JP-A No. 62-253159, pages 29 to 31 can be used.

The surface of these supports may be coated with a hydrophilic binder, a semiconductive metal oxide such as alumina sol or tin oxide, carbon black or other antistatic agent.

Examples of the method for exposing and recording an image on the light-sensitive element include a method of directly photographing a landscape or a person using a camera, a method of exposing through a reversal film or a negative film using a printer or an enlarger, or a copying machine. A method of scanning and exposing an original image through a slit using an exposure device, a method of exposing image information by emitting light from a light emitting diode, various lasers, etc. via an electrical signal, image information of CRT, liquid crystal display, electroluminescence There is a method of outputting to an image display device such as a sense display and a plasma display and exposing directly or through an optical system.

As a light source for recording an image on a photosensitive element, as described above, natural light, a tungsten lamp, a light emitting diode, a laser light source, a CRT light source, etc., U.S. Pat.
The light source described in the column can be used.

Further, the image information is an image signal obtained from a video camera, an electronic still camera, a television signal represented by the Nippon Television Signal Standard (NTSC), or an image obtained by dividing an original image into many pixels such as a scanner. An image signal created using a computer represented by Signal, CG, CAD can be used.

The heating temperature in the heat development step is about 50 ° C. to about 250 ° C., and development is possible, but about 80 ° C. to about 180 ° C. is particularly useful. The dye transfer process may be performed at the same time as the heat development, or may be performed after the end of the heat development process. In the latter case, the heating temperature in the transfer step can be transferred in the range from the temperature in the heat development step to room temperature, but it is particularly preferably 50 ° C. or higher and about 10 ° C. lower than the temperature in the heat development step.

The migration of the dye occurs only by heat, but a solvent may be used to promote the dye migration.

Further, as described in detail in JP-A-59-218443, JP-A-61-238056 and the like, a method of performing development and transfer simultaneously or continuously by heating in the presence of a small amount of solvent (particularly water) is also available. It is useful. In this method, the heating temperature is preferably 50 ° C or higher and not higher than the boiling point of the solvent, for example, 50 ° C or higher when the solvent is water.
100 ° C or less is desirable.

Examples of the solvent used for accelerating the development and / or transferring the diffusible dye to the dye-fixing layer include water or a basic aqueous solution containing an inorganic alkali metal salt or an organic base (for these bases, an image). Those described in the section of the formation accelerator are used). Further, a low boiling point solvent, or a mixed solution of a low boiling point solvent and water or a basic aqueous solution can be used. Further, a surfactant, an antifoggant, a sparingly soluble metal salt and a complex-forming compound, etc. may be contained in the solvent.

These solvents can be used by a method of applying them to the dye fixing element, the photosensitive element or both. The amount used may be as small as the weight of the solvent corresponding to the maximum swelling volume of the entire coating film or less (particularly the amount of the solvent corresponding to the maximum swelling volume of the entire coating film less the weight of the total coating film).

Examples of the method of applying a solvent to the photosensitive layer or the dye fixing layer include the method described in JP-A No. 61-147244, page (26). Alternatively, the solvent may be contained in a microcapsule and previously incorporated in the light-sensitive element or the dye-fixing element or both of them.

Further, in order to promote dye transfer, a method in which a hydrophilic thermal solvent that is solid at room temperature and dissolves at high temperature is incorporated in the photosensitive element or the dye fixing element can also be adopted. The hydrophilic thermal solvent may be incorporated in either the photosensitive element or the dye fixing element, or may be incorporated in both. The layer to be incorporated may be any of an emulsion layer, an intermediate layer, a protective layer and a dye fixing layer, but it is preferably incorporated in the dye fixing layer and / or its adjacent layer.

Examples of hydrophilic thermal solvents include ureas, pyridines, amides, sulfonamides, imides, alkenyls, oximes and other heterocycles.

Further, a high-boiling point organic solvent may be contained in the light-sensitive element and / or the dye-fixing element in order to promote dye transfer.

The heating method in the developing and / or transferring step may include contact with a heated block or plate, contact with a hot plate, a hot presser, a heat roller, a halogen lamp heater, an infrared or far infrared lamp heater, or a high temperature. There is a passage through the atmosphere. Further, a resistance heating element layer may be provided on the photosensitive element or the dye fixing element, and the resistance heating element layer may be energized for heating. As the heating element layer, those described in JP-A-61-145544 can be used.

The method described in JP-A-61-147244, page (27) can be applied to the pressure condition and the method of applying pressure when the light-sensitive element and the dye fixing element are superposed and brought into close contact with each other.

Any of a variety of thermal development apparatus can be used in processing the photographic elements of this invention. For example, JP-A-59-75247 and 59-1.
77547, 59-181353, 60-18951, 62-62
The devices described in No. 25944 and the like are preferably used.

In the present invention, the light-sensitive material after heat development can be desilvered using a known bleach-fixing sheet, bleach-fixing solution or bleaching solution and fixing solution to obtain a positive color image.

Example 1 Method for Preparing Internal Latent Image Emulsion (I) An aqueous solution of potassium bromide and an aqueous solution of silver sulfate were added in an amount of 0.3 g per mol of silver. At 75 ° C with vigorous stirring in a gelatin aqueous solution containing
It was added simultaneously over 20 minutes to obtain an octahedral monodisperse silver bromide emulsion having an average grain size of 0.4 μm.

To this emulsion were added 6 mg of sodium thiosulfate (pentahydrate) and chloroauric acid (tetrahydrate) per mol of silver, respectively.
Chemical sensitization was performed by heating at ℃ for 80 minutes. With the silver bromide particles thus obtained as the core, potassium bromide and silver sulfate were added for an additional 40 minutes in the same precipitation environment as when the core particles were formed, and finally the average particle size was 0.7 μm.
To obtain an octahedral monodisperse core / shell silver bromide emulsion. Wash
After desalting, 1.5 mg each of sodium thiosulfate and chloroauric acid (tetrahydrate) were added to this emulsion per mol of silver,
The mixture was heated at 60 ° C. for 60 minutes for chemical sensitization to obtain an internal latent image type emulsion.

Example 2 Method for Preparing Internal Latent Image Emulsion (2) An aqueous solution of potassium bromide and an aqueous solution of silver sulfate were vigorously placed in an aqueous gelatin solution containing potassium bromide (700 ml of water containing 30 g of gelatin and 6 g of potassium bromide). A silver bromide emulsion was obtained by mixing at the same time with stirring at 75 ° C. for 60 minutes and simultaneously. PAg was kept at 8.8 during the addition.

Before precipitation (simultaneous mixing), 0.15 g of silver halide solvent was added to the gelatin aqueous solution as a silver halide solvent. 15 g was added.

When the precipitation was completed, octahedral silver bromide crystals having an average particle size of 0.8 μm and a uniform particle size were produced. Next, add 4.8 mg of sodium thiosulfate to 1 mol of silver.
Add (5 hydrate) and 2.4 mg of chloroauric acid (tetrahydrate) 75
Chemical sensitization was performed by heating at ℃ for 80 minutes. In the thus chemically sensitized core silver bromide emulsion, an aqueous solution of potassium bromide and silver nitrate was added for 45 minutes at the same pAg as when the core grains were formed, and the mixture was added simultaneously.
The shell emulsion was precipitated, and 2.5 g of hydrogen peroxide was added as an oxidant per mol of silver and the mixture was heated at 75 ° C. for 8 minutes and washed with water to obtain an octahedral silver bromide emulsion having an average particle diameter of 1 μm. Next, to this internal latent image type core / shell silver bromide emulsion, 0.75 mg of sodium thiosulfate (pentahydrate) and 20 mg of poly (N-vinylpyrrolidone) were added per mol of silver, and the mixture was added at 60 ° C. to 60 ° C.
After heating for a minute, the grain surface was chemically sensitized.

The concentration of the silver aqueous solution used in the preparation of the core / shell emulsion was 1 mol AgNO ₃ /1.25l for both the core and shell parts. 0.36 mol of silver was added to form particles in the core part. 0.34 mol silver was added for formation.

The concentration of the potassium bromide aqueous solution was 1 mol KBr / 1 in both the core part and the shell part.

Example 3 A light-sensitive material (A) was prepared by sequentially coating the following layers (I) to (IX) on a transparent polyethylene terephthalate support.

Layer (I) Layer (II) Layer (III) Layer (IV) Layer (V) ... same intermediate layer as layer (II) Layer (VI) ... same alkali generator layer as layer (III) Layer (VII) Layer (VIII) ... Alkali generator layer same as layer (III) Layer (IX) A photosensitive material (B) which was the same as the photosensitive material (A) except that the nucleating agent 22 was replaced by the nucleating agent 15, and a photosensitive material (C) in which the nucleating agent X having the following structure was replaced for comparison were also prepared. .

Further, the following layers were sequentially coated on a white paper support laminated with polyethylene terephthalate to prepare a dye fixing material.

Layer (X) Layer (XI) After exposing the above light-sensitive materials (A) to (C) from the base side through a wedge at 100 CMS, water was uniformly applied (20 g /
m ² ), and the light-sensitive material and the dye-fixing material were superposed so that the respective film surfaces face each other.

Next, pass this through a heat roller heated so that the temperature of the film surface becomes 90 ° C, and after heating for 20 seconds, remove the dye fixing material from the photosensitive material and obtain a positive transfer color image on the fixing material. Obtained.

The results of sensitometry are shown in Table 1. With the nucleating agent (X) for reference, almost no positive dye image can be obtained, whereas with the nucleating agents 22 and 15 according to the present invention, a clear positive image can be obtained. Recognize.

(Compound described in U.S. Pat. No. 3,330,655) Example 4 The following layers (I) to (IX) were sequentially coated on a support to prepare a light-sensitive material (A).

Layer (I) Layer (II) Layer (III) ... The same alkali generator layer as layer (III) of Example 3 Layer (IV) Layer (V) ... same intermediate layer as layer (II) Layer (VI) ... same alkali generator layer as layer (III) Layer (VII) Layer (VIII) ... Same alkali generator layer as layer (III) Layer (IX) ... Same protective layer as layer (IX) of Example 3 Nucleating agent 10
Except that the nucleating agent 25 was replaced by the same photosensitive material (B) as the photosensitive material (A) and the nucleating agent (X) for comparison was replaced by the same photosensitive material (A) as the photosensitive material (C). Prepared.

After exposing the above light-sensitive materials (A) to (C) from the film surface side at 100 CMS, the same dye-fixing material as in Example 3 was used and the same treatment was carried out.

The results of the obtained sensitometry are shown in Table 2. It can be seen that the nucleating agent of the present invention can obtain a sufficient positive image of discrimination.

Example 5 The following layers (I) to (VI) were sequentially coated on a paper support laminated on both sides with polyethylene to prepare a light-sensitive material.

Layer (I) Layer (II) Layer (III) Layer (IV): Same intermediate layer as layer (II) Layer (V) Layer (VI) After exposing the above photosensitive material to 10 CMS from the film surface side,
The film surface side was brought into close contact with a heat block heated to ℃ and developed for 30 seconds.

Thereafter, a bleach-fixing solution having the following composition was used for desilvering treatment at 33 ° C. for 1 minute and 30 seconds, followed by thorough washing with water and drying.

Bleach-fix solution composition The photographic properties of the obtained positive image are shown below.

It can be seen that the use of the nucleating agent of the present invention makes it possible to obtain a positive image having sufficient discrimination.

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Claims (2)

[Claims] 1. A heat-developable photosensitive element containing at least an internal latent image type silver halide emulsion, a reducing agent and / or a precursor thereof, and a compound represented by the following general formula [I] on a support. A characteristic positive image forming method. General formula [I] In the formula, Z ¹ represents a nonmetallic atom group necessary for forming a 5- or 6-membered heterocycle. An aromatic ring or a heterocycle may be further condensed with this heterocycle. R ¹ is an aliphatic group, Is. Q represents a 4- to 12-membered non-aromatic hydrocarbon ring or a non-metal atom group necessary for forming a non-aromatic heterocycle. However, at least one of the substituents of R ¹ and Z ^{1 and} the substituent of Q includes an alkynyl group. Further, at least one of R ¹ , Z ¹ , and Q may have an adsorption promoting group on silver halide, Y is a counter ion for charge balance, and n is for charge balance. It is the required number. 2. The method for forming a positive image according to claim 1, wherein the photosensitive element is thermally developed in the presence of water and a base and / or a base precursor.