US3756829A

US3756829A - Thermally developable lightsensitive elements

Info

Publication number: US3756829A
Application number: US00701065A
Authority: US
Inventors: T Masuda; K Ohkubo; J Noguchi
Original assignee: Fuji Photo Film Co Ltd
Current assignee: Fujifilm Holdings Corp
Priority date: 1967-01-27
Filing date: 1968-01-29
Publication date: 1973-09-04
Anticipated expiration: 1990-09-04
Also published as: FR1553299A; GB1205500A; DE1622277A1

Abstract

A THERMALLY DEVELOPABLE LIGHT-SENSITIVE ELEMENT COMPRISING A SUPPORT BEARING, AT LEAST ONE LAYER CONTAINING AT LEAST (A) A LIGHT INSENSITIVE AND REDUCIBLE ORGANIC SILIVER SALT, (B) AT LEAST ONE MEMBER SELECTED FROM THE GROUP CONSISTING OF A SILVER HALIDE AND AN INORGANIC HALIDE CAPABLE OF FORMING A SILVER HALIDE BY THE REACTION THEREOF WITH SAID ORGANIC SILVER SALT (A), AND (C) A REDUCING MATERIAL CAPABLE OF BEING DECOMPOSED BY THE IRRADIATION WITH ACTINIC RADIATION TO LOSE ITS REDUCING PROPERTIES, WHICH CONTACTS AT LEAST ONE MATERIAL CAPABLE OF ACCELERATING THE DECOMPOSITION OF THE REDUCING MATERIAL BY IRRADIATION WITH ACTINIC RADIATION IN AT LEAST ONE LAYER THEREOF.

Description

. g States Patent Olfice 3,75%,829 Patented Sept. 4, 1973 ,3 int. Cl. G03c 1/02, 1/76, 3/00 ILS. Cl. 96-4141 11 (Ilaims ABSTRACT OF THE DISCLOSURE A thermally developable light-sensitive element comprising a support hearing, at least one layer containing at least (a) a light insensitive and reducible organic silver salt, (b) at least one member selected from the group consisting of a silver halide and an inorganic halide capable of forming a silver halide by the reaction thereof with said organic silver salt (a), and (c) a reducing material capable of being decomposed by the irradiation with actinic radiation to lose its reducing properties, which contacts at least one material capable of accelerating the decomposition of the reducing material by irradiation with actinic radiation in at least one layer thereof.

BACKGROUND OF THE INVENTION (1) Field of the invention The present invention relates to a thermally developable light-sensitive element and more particularly, to a thermally developable light-sensitive element containing, as a reducing agent, a compound capable of being decomposed by irradiation with actinic rays, and a compound capable of accelerating the decomposition of the reducing agent by irradiation with actinic rays. 'lhe invention also relates to copying processes using such elements.

(2) Description of the prior art In general, a photographic light-sensitive element in which a silver halide is used has been most widely employed as a light-sensitive element, since such a photographic silver halide light-sensitive element is excellent in sensitivity and gradation as compared with electrophotographic light-sensitive elements and other photographic light-sensitive elements.

However, in this photographic silver halide light-sensitive element, there are such difficulties that the lightsensitive element must be subjected to several processing steps, that is, stopping, fixing, and stabilizing in order to prevent the developed image from becoming discolored or faded and also to prevent the background thereof from being blackened.

Therefore, it is very desirable to obtain light-sensitive elements which can be easily fixed or stabilized after development.

The inventors have previously providied, as the aforesaid light-sensitive element including a simple stabilization processing, a thermally developable light-sensitive element comprising a support hearing at least one layer containing at least (a) a light insensitive and reducible organic silver salt, (b) a silver halide or an inorganic halide capable of forming a light-sensitive silver halide by the reaction with the organic silver salt (a), and (c) a developing agent or a reducing material capable of being decomposed by the irradiation of actinic rays to lose its reducing properties.

When the thermally developable light-sensitive element as mentioned above is exposed to an incandescent tungsten lamp in the usual manner and then developed by heating, the light exposed portions are blackened to provide photographic images. When the light-sensitive element thus developed is placed in the light, the reducing material (that is, the developing agent) is decomposed by the action of actinic rays included in sunlight or light from an ultraviolet lamp to lose its reducing properties. In other Words, the light-sensitive element which has been left in the light after exposure and development provides stabilized reproductions or images which are not to be developed any more in the light exposed portions even by heating again. That is, the aforesaid light-sensitive element can be fixed by exposure to light. Moreover, when the aforesaid light-senitive element is placed in the light after development, it is fixed spontaneously, in other Words, the aforesaid light-sensitive element requires no fixing processing.

Also, the thermally developable light-sensitive element containing such a reducing material can be used as an autopositive element. That is, when, after imagewise exposing the thermally developable light-sensitive element by actinic rays, the light-sensitive element is slightly exposed uniformly to a tungsten light and then developed by heating, the reducing material at the portions exposed to the actinic rays is decomposed or loses its reducing properties and hence, the exposed portions will not be developed when the thermally developable light-sensitive element is heated thereafter. On the other hand, since the reducing agent or the developing agent at the portions which have not been subjected to exposure with actinic rays remains undecomposed, the nonexposed portions will be developed by the subsequent uniform tungsten lamp exposure and heating. Accordingly, it will be understood that the thermally developable light-sensitive element containing such a reducing material can be used as autopositive light-sensitive elements.

The inventors have found that the light fixing property of the thermally developable light-sensitive element and the sensitivity thereof as an autopositive light-sensitive element can be further improved by incorporating a compound capable of accelerating the decomposition of a reducing material by an actinic irradiation in a thermally developable light-sensitive element containing the reducible material capable of being decomposed by the actinic radiation to lose its reducing power.

Thus, an object of this invention is to provide a thermally developable light-sensitive element capable of providing both a negative copy and a positive copy of an original according to the kind of light source used for exposure.

Another object of this invention is to provide a thermally developable light-sensitive element having a high sensitivity and capable of being developed by only heating Without using developing solution and that the image developed by heating is stabilized to light without being processed by fixing or the like and can be stored substantially permanently.

SUMMARY OF THE INVENTION These objects can be attained by incorporating a compound capable of accelerating the decomposition of a reducing material by the actinic irradiation in the thermally developable light-sensitive element comprising a support bearing at least one layer containing at least (a) A light-insensitive and reducible organic silver salt,

(b) A silver halide or an inorganic halide capable of forming a light-sensitive silver halide by the reaction with the light insensitive organic silver salt (a), and

(c) A reducing material capable of being decomposed by the irradiation of actinic rays to lose its reducing properties.

That is, by incorporated the compound capable of accelerating the decomposition of the reducing material by the irradiation of actinic rays in the aforesaid thermally developable light-sensitive element, the light-sensitive element can be developed by a completely dry process to provide very stable reproductions or images without fixing or other troublesome processings. In particular, since the reducing material contained in the light sensitive element is easily decomposed by the irradiation of actinic rays according to the present invention, the stability of the images obtained by the thermal development is further increased.

DETAILED DESCRIPTION OF THE INVENTION The light insensitive and reducible silver salt to be used in the present invention may be a silver salt of an organic compound having an imino group, a silver salt of an organic compound having a mercapto group, or a silver salt of an organic acid. In these silver salts, there are included light insensitive silver salts and light-sensitive silver salts. Also, some silver salts shown highly reducible properties while other silver salts show weak reducible properties. Among them, the silver salts suitable for the present invention are ones having light insensitivity or very low sensitivity and having high reducible properties.

As examples of silver salts which have been found to be suitable for the present invention, there are illustrated a silver salt of 1,2,3-benzotriazole, a silver salt of benzosulfimide, a silver salt of 3-mercapto-4-phenyl-1,2,4-triazole, a silver salt of l-phenyl-S-mercapto-tetrazole, a silver salt of 4-hydroxy-6-methyl-1,3,3a,7-tetrazaindene, a silver salt of 2-(S-ethylthioglycloamido)benzothiazole, a silver salt of myristic acid, a silver salt of lauric acid, a silver salt of palmitic acid, a silver salt of stearic acid, and a silver salt of behenic acid.

The inorganic halide capable of forming a light-sensitive silver halide used in this invention is a compound soluble in water or in an organic solvent, said compound being represented by the general formula:

wherein M represents a hydrogen atom, ammonium, and a metal (such as, strontium, cadmium, zinc, tin, chromium, sodium barium, iron, cesium, lanthanum, copper, calcium, nickel, magnesium, potassium, aluminum, antimony, gold, cobalt, mercury, lead, and beryllium); X represents a halogen atom (such as, chlorine, bromine, and iodine); and n is a valence of M.

Among them, the iodides are particularly preferable as the silver salt thereof has the properties that it is difficult to be printed out.

The reducing material in this invention, which can be decomposed by the irradiation of actinic rays to lose its reducing properties is a compound having the group represented by the general formula:

wherein R and R represent a hydrogen atom, an alkyl group, or an acyl group and n is an integer selected from and 1.

Among the compounds represented by the above general formulae, the suitable examples for the present invention are illustrated l-ascorbic acid, l-ascorbyl monoester, l-ascorbyl diester, furoin, benzoin, dihydroxyacetone, 1,2-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4-methoxy-1-naphthol, and 4 ethoxy 1 naphthol. These compounds can be decomposed by the irradiation of an actinic radiation.

Moreover, as the material used in this invention. which can accelerate the decomposition of the aforesaid reducing material by the irradiation of an actinic ray, there may be effectively employed a compound capable of forming an excited molecule or a radical by the irradiation of actinic rays or a dye which is easily decomposed by the irradiation of actinic rays.

That is, there are the following compounds (1)-(4) capable of forming excited molecules or radicals by the irradiation of actinic rays and dyes (5) capable of being easily decomposed by the irradiation of actinic rays. Thus,

(1) Diketones, such as diacetyl or benzil;

(2) Polynuclear aromatic compound, such as anthra cene, fiuorenone, 9,10 anthraquinone, 2 chloroanthraquinone, fl-methylanthraquinone;

(3) Metal oxides, such as stannic oxide, cupric oxide, manganese oxide, or magnesium oxide; and

(4) Light-sensitive cerium compound, such as cerium nitrate, 4

(5) Dyes (a) phthalein dyes, such as erythrosine, eosine, and

Rhodamine B,

(b) cyanine dyes, such as 3,3-diethylthiazolinocarbocyanine iodide, 1-ethyl-3-propyl 5 [2 (lmethy1-2(1H)-pyrrolinylidene)ethylidene] 2 thiohydantoin, and

(c) others, such as Methylene Blue, Methyl Violet,

profiavine, phenosafranine, and Chrysoidine.

The proportion of the above-mentioned material for accelerating the decomposition of the reducing agent by an actinic irradiation is influenced by the combination of the above-mentioned material and the reducing material, but it is preferable to use to 20 parts by weight in diketones (l), to 10 parts by weight in polynuclear aromatic compounds (2), to 10 parts by weight in metal oxides, to 10 parts by weight in cerium compounds (4) and to one part by weight in dyes (5) per one part by weight of the reducing material.

If the amount of the material is lower than this proportion, there is little effect, and if the amount thereof is higher, the shelf life of unexposed light-sensitive elements will be reduced.

Further, by employing these material in combination, the decomposition accelerating effect may be increased.

In the case of using the thermally developable lightsensitive elements of this invention as usual negative working, the light-sensitive element may be, after being exposed to a tungsten lamp, developed by only heating. On the other hand, the thermally developable light-sensitive element of the present invention may be utilized as an autopositive light-sensitive element. That is, after exposing the thermally developable light-sensitive element to actinic rays imagewise to an extent of decomposition the reducing material contained in the light-sensitive element, the light-sensitive element thus imagewise exposed is exposed again uniformly to actinic radiation or light from an incandescent lamp to an extent by which the reducing material is not decomposed and thereafter is developed by heating, whereby the reducing material at the areas exposed to the first actinic radiation is decomposed, that is, the developing agent loses its developing power. Thus, when the light-sensitive element is heated thereafter, the exposed area will not be developed. On the other hand, there remains undecomposed reducing agent at the areas which had not been irradiated by the first actinic rays, and hence, by the subsequent uniform weak irradiation of the actinic rays or exposure to the tungsten lamp followed by heating, the areas where there remained reducing agent undecomposed are developed. Therefore, the thermally developable light-sensitive element may be utilized as an autopositive light-sensitive element.

In particular, in the case of the thermally developable light-sensitive element of this invention is used as autopositive light-sensitive element, the whole processes are conducted by dry systems too. When the whole process has been conducted, the reducing agent at the image areas,

as well as at the background areas has been decomposed, and then, no more development proceeds in the lightsensitive element thus developed during storage. Thus, the light-sensitive element developed will not be discolored substantially permanently and consequently, the contrast between densities of the image areas and the background areas thereof will be kept high for a long period of time.

In the thermally developable light-sensitive element previously provided by the inventors (see Ser. No. 643,828, filed June 6, 1967) which comprises a support hearing at least one layer containing at least (a) a light insensitive and reducible organic silver salt, (b) a silver halide or an inorganic halide capable of forming a lightsensitive silver halide by the reaction with the organic silver salt (a) and (c) a developing agent or a reducing material capable of being decomposed by the irradiation of actinic rays to lose its reducing properties, it took more than 5 minutes to decompose the reducing material by irradiating with the light from a high pressure mercury lamp of 400 watts the thermally developable light-sensitive element placed with a distance of cm. from the light source. Accordingly, the previous light-sensitive element invented by us is insufliciently used as an autopositive light-sensitive element. On the other hand, in the thermally developable light-sensitive element of the present invention containing the material which can accelerate the decomposition of the reducing agent by light exposure, the reducing agent therein is sufliciently decomposed when the light-sensitive element is irradiated for one minute by a high pressure mercury lamp of 400 watts a distance of 10 cm. from the light source. The sensitivity of the element has increased as much as four times. Further, with a high pressure mercury lamp of 1200 watts, the reducing agent will be decomposed by the irradiation of -30 seconds.

The thermally developable light-sensitive element of this invention has the following advantages:

(1) Excellent in shelf life thereof in the unexposed state.

(2) Excellent in shelf life after processing without necessity of processing such as fixing and stabilizing processing after development as the light-sensitive element is stabilized by the irradiation of an active ray.

(3) Utilization thereof for negative working, as well as for positive working.

The invention will be explained practically by the following examples but the invention should not be limited to the following examples by any means.

EXAMPLE 1 A uniform dispersion having the following composition was applied to a paper (per 1 sq. m. thereof) and dried:

"3 ethyl-5-[ (3-methyl-2-thiazolinllidene) ethylidene1-rhodanine (of.; Journal of Physical Chemistry, vol. 56, 1062 (1952).

The dry thickness was 10 microns. The light-sensitive element thus prepared was exposed imagewise to a tungsten lamp and heated to 120 C. for 10 seconds to provide a good negative image. When the light-sensitive paper thus developed was further exposed to white light, the

contrast between the image areas and the background areas was not varied.

Another unexposed sample was superposed on a transparent original having patterns, the light-sensitive paper was then exposed for one minute through the original to a high pressure mercury lamp of 400 watts with a distance of 10 cm. from the light source, and the original was removed. Thereafter, the light-sensitive element thus processed was further exposed for a short period of time to a tungsten lamp and heated to C. for 10 seconds to provide a good positive image. Furthermore, another new sample of this example was superposed on a transparent original and exposed for 15 seconds through the original to a high pressure mercury lamp of 1200 watts with a distance of 10 cm. from the light source. After removing the original, the light-sensitive element was further exposed for a short period of time to a tungsten lamp and then heated to 120 C. for 10 seconds to provide a good positive image.

When these light-sensitive papers thus developed were further exposed to white light, the contrast between the images and the backgrounds was not varied.

EXAMPLE 2 A uniform dispersion having the following composition was applied to a paper (per one sq. m. thereof) and dried to form a light-sensitive layer having a dry thickness of 10 microns:

Polyvinyl butyral (15 wt. percent methanol solution)18 Ascorbyl palmitate0.12 g. Sodium benzenesulfinate0.-06 g. Benzil--0.6 g.

Sebacic acid-2.4 g.

*The same merocyanine dye as in Example 1.

When the light-sensitive paper thus prepared was exposed to a tungsten lamp and heated for 10 minutes to 120 C., a good negative image was obtained.

Further, another sample, same as above, was superposed on a transparent original and exposed for 20 seconds through the original to a high pressure mercury lamp of 1200 watts with a distance of 10 cm. from the light source. After removing the transparent original, the lightsensitive paper was exposed again for a short period of time to a tungsten lamp and heated for 10 seconds to 120 C. to provide a good positive image having a high contrast, which was not varied when the light-sensitive paper was placed in white light for a long period of time.

EXAMPLE 3 A uniform dispersion having the following composition was applied to a paper (per one sq. m. thereof) and dried to form a layer of 10 microns in dry thickness.

Polyvinyl butyral (15 wt. percent methanol solution)- Silver salt of benzotriazole (15 wt. percent methanol dispersion)-15 ml.

Potassium iodide (l/SO N methanol sol.)-15 ml.

Sensitizing dye*-(0.25 wt. percent methanol sol.)0.4

After removing the transparent original, the light-sensitive paper was uniformly exposed to visible light for a short period of time and then heated to 120 C. for 10 seconds to provide a good positive image with white background. When the light-sensitive paper thus developed was placed in white light, the contrast between the image and the background was not varied.

EXAMPLE 4 A uniform dispersion having the following composition was applied to a paper and dried to form a layer of 10 microns in dry thickness:

Polyvinyl butyral (15 wt. percent methanol solution)- Silver salt of benzotriazole (15 wt. percent methanol dispersion)-25 ml.

Potassium iodide (1/50 N methanol sol.)25 ml. Sensitizing dye*(0.25 wt. percent methanol sol.)-0.6

4-methoxy-l-naphthol0.3 g. Sodium benzenesulfinate--0.l g. Manganese dioxide (1 wt. percent methanol dispersion)- Sebacic acid-4.5 g.

*The same merocyanlne dye as in Example 1.

By processing the light-sensitive paper thus prepared as in Example 1, a good negative image which could be fixed by light was obtained and also by exposure to ultraviolet rays, a positive image was obained as in Example 1.

EXAMPLE 5 A uniform dispersion having the following composition was applied to a paper and dried to form a layer of 10 microns in dry thickness:

Polyvinyl butyral (15 wt. percent methanol solution)30 Silver salt of benzotriazole (15 wt. percent methanol dispersion)-25 ml.

Potassium iodide (1/50 N methanol solution)25 ml.

Sensitizing dye*(0.25 wt. percent methanol sol.)0.6

3,3'-diethylthiazolinocarbocyanine iodide0.2 g.

Ascorbyl palmitate--0.2 g.

Sodium benzenesulfinate-0.1 g.

Sebacic acid-4.5 g.

*The same merocyanine dye as in Example 1.

By processing the light-sensitive paper as in Example 1, a good negative image which could be fixed by light was obtained and also by the exposure to ultraviolet rays, a positive image Was obtained.

EXAMPLE 6 A uniform dispersion having the following composition was applied to a paper (per one sq. m.) and dried to form a layer of 10 microns in dry thickness.

Polyvinyl butyral (15 wt. percent methanol solution)- Silver salt of 6-bromobenzotriazole (15 wt. percent methanol dispersion)25 ml.

Zinc iodide (1.50 N methanol solution)-25 ml.

Sensitizing dye (0.025 wt. percent methanol solution)- Ascorbyl stearate-0.4 g.

9,l-Anthraquinone0.6 g.

Sebacic acid4.0 g.

Magnesium oxide wt. percent methanol dispersion) *The same dye as in Example 3.

When the light-sensitive paper thus prepared was exposed to a tungsten lamp and heated for 10 seconds to 120 C., a good negative image was obtained. Also, another unexposed sample was superposed on a transparent original and exposed for 20 seconds through the original to a high pressure mercury lamp of 1200 watts with a distance of 10 cm. from the light source. After removing the original therefrom, the light-sensitive paper was exposed again uniformly to visible light for a short period of time and heated to C. for 10 seconds to provide a positive image.

EXAMPLE 7 A uniform dispersion having the following composition was applied to a paper (per one sq. m.) and dried.

Polyvinyl butyral (15 wt. percent methanol solution)lS Silver salt of benzotriazole (15 wt. percent methanol dispersion)-25 ml.

Ascorbyl dipalmitate0.6 g.

Benzil--2.5 g.

Sebacic acid-4.0 g.

To the layer thus formed (per one sq. m.) was applied a uniform dispersion having the following composition and dried:

Polyvinyl butyral (15 wt. percent methanol solution)lS Strontium iodide (l/50 N methanol solution)25 ml.

Sensitizing dye* (0.025 wt. percent methanol solution) The same merocyanlne dye as in Example 3.

When the light-sensitive paper thus prepared was exposed to a tungsten lamp and heated for 10 seconds to 120 C., a negative image was obtained. Also, the other unexposed sample was superposed on a transparent original and exposed for 30 seconds through the original to a high pressure mercury lamp of 1200 watts with a distance of 10 cm. from the light source. After removing the original therefrom, the light-sensitive paper was exposed for a short period of time to a tungsten lamp and heated for 15 seconds to 120 C. to provide a good positive image.

EXAMPLE 8 A uniform dispersion having the following composition was applied to a paper (per one sq. m.) and dried:

Polyvinyl butyral (15 wt. percent methanol solution)-30 Silver salt of 5-methyl-7-hydroxy-1,3,5-triazaindolizine (15 wt. percent methanol dispersion)25 ml.

Potassium iodide (1/50 N methanol solution)-25 ml.

Sensitizing dye* (0.025 wt. percent methanol solution) 1,4-dihydroxynaphthalene-O.6 g.

Diacetyl1.5 g.

Sebacic acid-4.0 g.

*The same merocyanine dye as in Example 1.

When the light sensitive paper thus prepared was exposed to a tungsten lamp and heated for 10 seconds to 120 C., a negative image was obtained. Also, the other unexposed sample was superposed on a transparent original and exposed for 30 seconds to a high pressure mercury lamp of 1200 watts with a distance of 10 cm. from the light source. After removing the transparent original, the light-sensitive paper was exposed again to a tungsten lamp for a short period of time and heated to 120 C. for 10 seconds to provide a good positive image.

What is claimed is:

1. A thermally developable light-sensitive element which is light-stable after development comprising a support bearing thereon at least one layer containing at least (a) a light-insensitive and reducible organic silver salt selected from the group consisting of a silver salt of an organic compound having an imino group, a silver salt of an organic compound having a mercapto group and a silver salt of an organic acid;

(b) at least one member selected from the group consisting of a silver halide and an inorganic halide capable of forming a silver halide by the reaction thereof with said organic silver salt (a);

(c) a reducing material capable of being decomposed by irradiation with actinic radiation to lose its reducing properties, said reducing material being selected from the group consisting of compounds having the group represented by the general formula and compounds having the group represented by the general formula wherein R and R represent a member selected from the group consisting of a hydrogen atom, an alkyl group, and an acyl group and wherein n is an integer selected from and 1; and

(d) at least one member selected from the group consisting of (1) compounds forming excited molecules or radicals in response to irradiation with actinic radiation and selected from the group consisting of (i) diketones selected from the group consisting of diacetyl and benzil,

(ii) polynuclear aromatic compounds selected from the group consisting of anthracene, fluorenone, 9,10-anthraquinone, 2-chloroanthraquinone, and fi-methylanthraquinone,

(iii) metal oxides selected from the group consisting of stannic oxide, cupric oxide, manganese oxide and magnesium oxide, and

(iv) cerium nitrate; and

(2) dyes easily decomposed by irradiation with actinic radiation selected from the group consisting of erythrosine, cosine, Rhodamine B, 3,3 diethylthiazolino carbocyanine-carbocyanine iodide, 1-ethyl-3-propyl-5-(1-methyl-2 (1H) pyrrolinylidene)ethylidene) 2 thiohydantoin, Methylene Blue, Methyl Violet, proflavine, phenosafranine, and Chrysoidine; said member being capable of accelerating the decomposition of said reducing material by irradiation with actinic radiation.

2. The thermally developable light-sensitive element according to claim 1 wherein said reducing material is selected from the group consisting of l-ascorbic acid, l-ascorbyl monoester, l-ascorbyl diester, furoin, benzoin, dihydroxyacetone, 1,2-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4-methoxy-1-naphthol, and 4-ethoxyl-naphthol.

3. The thermally developable light-sensitive element according to claim 4 wherein said reducing material capable of being decomposed by irradiation with actinic radiation to lose its reducing properties is selected from to group consisting of l-ascorbic acid, l-ascorbyl monoester, l-ascorbyl diester, furoin, benzoin, dihydroxyacetone, 1,2-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4-methoxy-1-naphthol, and 4-ethoxy-1-naphthol.

4. The thermally developable light-sensitive element according to claim 1 wherein said silver salt is selected from the group consisting of the silver salt of benzotriazole, the silver salt of 6-bromobenzotriazole and the silver salt of 5-methyl-7-hydroxy-1,3,5-triazaindolizine.

5. The thermally developable light-sensitive element according to claim 1 wherein said inorganic halide is a metal iodide.

'6. The thermally developable light-sensitive element according to claim 2 wherein said inorganic halide is a water-soluble or organic solvent-soluble compound of the formula: MXn Where M represents a hydrogen atom, an ammonium group or a metal; X represents a halogen atom; and n is thevalence of M.

7. The thermally developable light-sensitive element according to claim 6 wherein the metal of said inorganic halide is selected from the group consisting of strontium, cadmium, zinc, tin, chromium, sodium, barium, iron, cesium, lanthanum, copper, calcium, nickel, magnesium, potassium, aluminum, antimony, gold, cobalt, mercury, lead, and beryllium.

8. The thermally developable light-sensitive element according to claim 3 wherein said inorganic halide is a water-soluble or organic solvent-soluble compound of the formula: MXn wherein M represents a hydrogen atom, an ammonium group or a metal; X. represents a halogen atom; and n is the valence of M.

9. The thermally developable light-sensitive element according to claim 8 wherein said layer consists essentially of said silver salt, at least one member selected from the group consisting of said silver halide and said inorganic halide, said reducing material and said member capable of accelerating the decomposition of said reducing material by irradiation with actinic radiation.

10. A process for obtaining a negative print of an original comprising exposing imagewise the thermally developable light-sensitive element described in claim 1 to light from a tungsten lamp and developing by heating to about C.

11. A process for obtaining a positive print of an original comprising exposing imagewise the thermally developable light-sensitive element described in claim 1 to actinic radiation from a mercury lamp, then exposing to light from a tungsten lamp, and developing by heating to about 120 C.

References Cited UNITED STATES PATENTS 3,526,505 9/1970 Workman 96-1141 3,529,963 9/ 1970 Marchese 96--114.1 3,152,904 10/1964 Sorenson et al. 96-1 14.1 3,409,438 11/1968 Lokken 96-114.1 3,429,706 2/ 1969 Shepard 96-114, 1 3,457,075 7/1969 Morgan 96114.1

NORMAN G. TORCHIN, Primary Examiner M. F. KELLEY, Assistant Examiner US. Cl. X.R. 96-67, 68