US3832212A - Heat-sensitive copying systems - Google Patents

Abstract

HEAT SENSITIVE COMPOUNDS CONTAINING HETEROCYCLIC NITROGEN ATOMS SUBSTITUTED WITH AN -OR GROUP FRAGMENT UNDER THE INFLUENCE OF VARIOUS FORMS OF ENERGY TO FORM A DYE BASE, A PROTON AND AN ALDEHYDE, THESE MATERIALS BEING USEFUL IN IMAGE REPRODUCTION.

Description

3,832,212 Patented Aug. 27, 1974 3,832,212 HEAT-SENSITIVE COPYING SYSTEMS Philip W. Jenkins, Donald W. Heseltine, and John D. Mee, Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y. No Drawing. Application Jan. 13, 1971, Ser. No. 106,231, now Patent No. 3,770,451, which is a division of application Ser. No. 766,307, Oct. 9, 1968, now Patent No. 3,615,432. Divided and this application Nov. 8, 1972, Ser. No. 304,674

Int. Cl. B41m 5/00 US. Cl. 11736.7 17 Claims ABSTRACT OF THE DISCLOSURE Heat sensitive compounds containing heterocyclic nitrogen atoms substituted with an OR group fragment under the influence of various forms of energy to form a dye base, a proton and an aldehyde, these materials being useful in image reproduction.

This is a division of application Ser. No. 106,231, filed Jan. 13, 1971, now US. Pat. 3,770,451, issued Nov. 6, 1973, which in turn is a division of Ser. No. 766,307, filed Oct. 9, 1968, now US. Pat. 3,615,432, issued Oct. 26, 1971.

This invention relates to a novel class of organic compounds and to novel photographic elements, compositions and processes using these compounds.

Various classes of dyes have known uses in different types of photographic systems. Perhaps one of the most common applications of dyes is their use as spectral sensitizers in silver halide emulsions. The native sensitivity of most silver halide emulsions falls within a very limited range of the visible portion of the spectrum (generally the blue region only). However, it is known that when certain dyes are added to silver halide emulsions, the sensitivity of the silver halide emulsion is extended to longer wavelengths. The sensitizing dyes are incorporated in the emulsion and are generally uniformly distributed throughout the emulsion. The methods used to incorporate the dyes are well known to those skilled in the art.

Dyes are also used to sensitize silver halide emulsions which produce direct positive images. Emulsions of this type may contain an electron acceptor and silver halide grains that have been fogged with a combination of a reducing agent and a compound of a metal more electro positive than silver. One of the advantages of such direct positive emulsions is that the highlight areas of the images obtained with these materials are substantially free from fog. However, known materials of this type have not exhibited the high speed required for many applications of photography. Also, such known materials have not shown the desired selective sensitivity, especially to radiation in the green to red region of the spectrum. Furthermore, in some instances as with known indole cyanine dyes, the inclusion of color-forming couplers or colored couplers in such emulsions has tended to reduce the sensitivity thereof in proportion to the length of the holding time, i.e., the time period from actual making the coating and curing the emulsion. This is a decided disadvantage since such emulsions cannot be held for any substantial period of time but must be coated immediately as formulated. It is apparent, therefore, that there is need in the art for improved direct positive photographic emulsions having not only good speed and selective sensitivity, but having, in addition, desirable holding or keeping stability.

In non-silver photographic systems, bleachable dyes can be used as photosensitive materials. Generally, these dyes are bleached in proportion to the exposure and direct positive images are attainable. Color direct positives are produced by an appropriate mixture of photobleachable cyan,

magenta and yellow dyes. The loss of color usually proceeds at a relative slow rate and even the use of sensitizers does not speed up the process enough'to'make it commercially attractive.

Dyes are also useful in thermographic systems. Recording elements frequently are impregnated with dyes which change color when subjected to localized heating. The heat necessary to cause the dye to react can be provided either by direct contact, such as hot stylus, or by exposure of a differentially radiation-absorptive graphic original to intense radiant energy while in contact with a dye-containing heat-sensitive element. The heat pattern established at the irradiated original causes a corresponding visible pattern to appear in the heat-sensitive layer, without deterioration of the original. A convenient source of radiation for thermographic reproduction is a tungsten filament lamp. The radiation is rich in infrared as well as visible light, and the process is particularly suited to the copying of originals having infrared-absorptive image areas. Certain of these thermographic materials which have been previously described are only slightly sensitive to visible light, and, consequently, prolonged exposures are necessary in order to produce acceptable copies. It is obvious that such materials have only limited use, and, in certain instances, cannot be used at all on a commercial basis.

Still another use of dyes in sensitive photographic elements is in layers for the reduction of halation or filtration of certain undesirable rays from the exposing radiation, either upon direct exposure or for re-exposure in a photographic reversal process. Antihalation layers can be coated as backing layers on either side of a transparent support carrying the light-sensitive composition. Light-filtering layers can be coated over the light-sensitive layers or between such layers in multilayer elements. The dyes used for such layers must have the desired spectral absorption characteristics. They should be easily incorporated in a water-permeable hydrophilic colloidal layer and yet firmly held in the layer so that they do not diffuse from it either during the manufacture of the element or on storing it. It is generally necessary to employ light-filtering dyes which can be quickly and readily rendered ineffective, i.e., decolorized or destroyed and removed prior to, during, or after photographic processing. For many purposes it is particularly convenient to employ dyes which are rendered ineifective by one of the photographic baths used in processing the exposed element, such as photographic developer or fixer in the case of silver halide photography. Prior art dyes which have desirable absorption characteristics have not always had good bleaching characteristics and reproductions made from photographic elements containing them have been subject to undesirable stains. Other dyes have not had the stability in aqueous gelatin that is desired.

It is an object of this invention to provide a novel class of energy-sensitive compounds.

Another object of this invention is to provide novel image-forming compositions and elements containing these compounds.

It is still another object of this invention to provide negative photographic silver halide emulsions sensitized with these novel compounds.

An object of this invention is also to provide heat-sensitive elements containing these novel compounds.

Another object is to provide novel dye-containing photobleachable elements.

Another object is to provide novel non-silver direct positive dye-bleach photographic elements capable of producing full color photographic prints.

It is still a further object of this invention to provide photographic elements having novel bleachable filter layers.

Also, an object is to provide photographic elements having novel antihalation layers.

It is another object of this invention to provide novel processes for producing images using novel compositions, compounds and elements.

These and other objects of the invention are accomplished with compounds having one of the general formulae:

wherein:

R; can be any of the following:

(a) a methine linkage terminated by a heterocyclic nucleus of the type contained in cyanine dyes, e.g., those set forth in Mees and James, The Theory of the Photographic Process, MacMillan, 3rd ed., pp. 198-232; the methine linkage can be substituted or unsubstituted, e.g., CI-I=, C(CH -C(C H -CH=C'H, CH=CHCH=, etc.;

(b) an alkyl radical preferably containing 1 to 8 carbon atoms including a substituted alkyl radical;

(c) an aryl radical including a substituted aryl radical such as a phenyl radical, a naphthyl radical, a tolyl radical, etc.;

(d) a hydrogen atom;

(e) an acyl radical having the formula JFK wherein R is hydrogen or an alkyl group preferably having 1 to 8 carbon atoms; (f) an anilinovinyl radical such as a radical having the formula wherein R is hydrogen or alkyl; or (g) a styryl radical including substituted styryl radicals,

wherein R is hydrogen, alkyl, aryl, amino including dialkylamino such as dimethylamino;

R can be either of the following:

(a) a methine linkage terminated by a heterocyclic nucleus of the type contained in merocyanine dyes, e.g., those set forth in Mees and James (cited above); the methine linkage can be substituted or unsubstituted; or

(b) an allylidene radical including a substituted allylidene radical such as a cyanoallylidene radical, an alkylcarboxyallylidene radical or an alkylsulfonylallylidene radical;

R can be either:

(a) an alkyl radical preferably having 1 to 8 carbon atoms such as methyl, propyl, ethyl, butyl, etc., including a substituted alkyl radical such as sulfoalkyl, e.g.,

an 'aralkyl, e.g., benzyl or pyridinato-oxyalkyl salt, e.g., -(CH O--Y wherein Y is a substituted or unsubstituted pyridinium salt; (b) an acyl radical, e.g.,

wherein R is an alkyl radical preferably having 1 to 8 carbon atoms or aryl radical, e.g., methyl, ethyl, propyl, butyl, phenyl, naphthyl, etc.;

(c) an aryl radical including a substituted aryl radical,

e.g., phenyl, naphthyl, tolyl, etc.;

Z represents the atoms necessary to complete a 5 to 6 membered heterocyclic nucleus including a substituted heterocyclic nucleus which nucleus can contain at least one additional hetero atom such as oxygen, sulfur, selenium or nitrogen, e.g., a pyridine nucleus, an indole nucleus, a quinoline nucleus, etc.; and

X represents an acid anion, e.g., chloride, bromide, iodide, perchlorate, sulfamate, thiocyanate, p-toluenesulfonate, methyl sulfate, tetrafluoroborate, etc.

These compounds are very versatile and can function in several different manners when used in photographic elements. They can be used as sensitizers in both direct positive and negative silver halide emulsions; they are heat bleachable and thus useful in thermographic recording elements; they are photobleachable and can be used for producing direct positives merely by coating them on a substrate; they make excellent antihalation layers and filter layers since they can be removed without the use of special baths simply by subjecting them to light for a sufficient period of time; and, when a mixture of a cyan, a magenta and a yellow dye having the above formula are coated on a support and exposed to a colored transparency, a direct color positive is obtained as a result of photobleaching. They are also useful in preparing holographic elements.

The compounds of this invention are chemically altered when subjected to various forms of energy such as (1) electromagnetic radiation including ultraviolet, visible and infrared light, X-rays, electron beams, laser beams, etc., (2) heat derived from various sources such as infrared radiation, (3) energy produced by mechanical means such as that produced by the local application of pressure, (4) sound waves, etc.

When the energy sensitive compounds of this invention are exposed to any of the various forms of energy enumerated above, the pursuant alteration is generally a fragmentation of the compound molecule. It is the resultant components of the fragmentation which may be used in the formation of images. The particular route of the fragmentation reaction is somewhat dependent upon the structure of the original compound. However, based upon observations, it is believed that the route followed when a dye of this invention (such as the one given below) is exposed to a form of energy (such as light) is the following:

I: CHaO- 4- CHaO I" 3* crno In this case photobleaching is effected by a heterolytic cleavage of the nitrogen-oxygen (NO) bond to produce a RO+ ion and a dye base which may in part fragment even farther. The dye base is useful in image reproduction. The remaining fragments are useful as initiators for other reactions such as polymerization and crosslinking as described in copending applications titled Photopolymerization and Crosslinka-ble Polymer Compositions filed concurrently herewith. The original color of the dye appears when it is treated with acid so that the pH of the material is below 7, but no further photobleaching results when the dye is exposed to energy. Each of the fragments produced can be used in various processes, e.g., the aldehyde is an effective crosslinking agent as described in the aforementioned application, or as a dye mordant. The free radicals and cations are useful as polymerization initiators as described in the aforementioned application. 1

While certain compounds of this invention are more effective for a particular utility than others, the preferred ones have one of the following structures:

wherein Q Q Q Q and Q each represent the non-metallic atoms necessary to complete a sensitizing or desensitizing nucleus containing 5 or 6 atoms in the heterocyclic ring,

which nucleus can contain at least one additional hetero atom such as oxygen, sulfur, selenium or nitrogen, i.e., a nucleus of the type used in the production of cyanine dyes, such as the following representative nuclei: a thiazole nucleus, e.g., thiazole, 4-methylthiazole, 3-ethylthiazole, 4-phenylthiazole, S-methylthiazole, 5-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, 4-(2-thienyl) thiazole, benzothiazole, 4-chlorobenzothiazole, 4- or 5-nitrobenzothiazole, S-chlorobenzothiazole, 6-chlorobenzothiazole, 7-ch1orobenzothiazole, 4-methylbenzothiazole, 5 methylbenzothiazole, 6 methylbenzothiazole, 6-nitrobenzothiazole, 5 bromobenzothiazole, 6-bromobenzothiazole, 5 chloro 6-nitrobenzothiazole, 4-phenylbenzothiazole, 4-methoxybenzothiazole, S-methoxybenzothiazole, 6 methoxybenzothiazole, 5 iodobenzothiazole, 6-iodobenzothiazole, 4-ethoxybenzothiazole, S-ethoxybenzothiazole, a tetrahydrobenzothiazole nucleus, 5,6-dimethoxy benzothiazole, 5,6 methylenedioxybenzothiazole, 5 hydroxybenzothiazole, 6-hydroxybenzothiazole, a-naphthothiazole, ,B-naphthothiazole, [3,,B-naphthothiazole, S-methoxy 5,5 naphthothiazole, 5-ethoxy-fimaphthothiazole, 8- methoxy or, naphthothiazole, 7 methoxy-a-naphthothiazole, 4 methoxythianaphtheno-7,6',4,5-thiazole, nitro group substituted naphthothiazoles, etc.; an oxazole nucleus, e.g., 4-methyloxazole, 4-nitro-oxazole, S-methyloxazole, 4-phenyloxazole, 4,5 diphenyloxazole, 4 ethyloxazole, 4,5-dimethyloxazole, S-phenyloxazole, benzoxazole, 5 chlorobenzoxazole, 5 methylbenzoxazole, 5 phenylbenzoxazole, 5- or 6-nitrobenzoxazole, 5-chloro-6-nitrobenzoxazole, 6 methylbenzoxazole, 5,6-dimethylbenzoxazole, 4,6-dimethylbenzoxazole, S-methoxybenzoxazole, 5- ethoxybenzoxazole, 5-chlorobenzoxazole, 6-meth0xybenzoxazole, S-hydroxybenzoxazole, 6-hydroxybenzoxazole, anaphthoxazole, fl-naphthoxazole, nitro group substituted naphthoxazoles, etc.; a selenazole nucleus, e.g., 4-methylselenazole, 4-nitroselenazole, 4-phenylselenazole, benzoselenazole, 5 chlorobenzoselenazole, 5 methoxybenzoselenazole, 5 hydroxybenzoselenazole, 5- or 6 nitrobenzoselenazole, 5 chloro 6-nitrobenzoselenazole, tetrahydrobenzoselenazole, a naphthoselenazole, p naphthoselenazole, nitro group substituted naphthoselenazoles, etc.; a thiazoline nucleus, e.g., thiazoline, 4-methylthiazoline, etc.; a pyridine nucleus, e.g., Z-pyridine, S-methyl- 2-pyridine, 4-pyridine, 3-methyl-4-pyridine, nitro group substituted pyridines, etc.; a quinoline nucleus, e.g., 2- quinoline, 3-methyl-2-quinoline, S-ethyl-Z-quinoline, 6- chloro-2-quino1ine, 6-nitro-2-quinoline, 8-chloro-2-quinoline, 6-methoXy-2-quinoline, S-ethoxy-Z-quinoline, 8-hydroxy-Z-quinoline, 4-quinoline, 6-methoxy-4-quinoline, 6- nitro 4 quinoline, 7-methy1-4-quinoline, 8-chloro-4- quinoline, l-iso-quinoline, 6-nitro-1-isoquinoline, 3,4-dihydro1-isoquinoline, 3-isoquinoline, etc.; a 3,3-dialkylindolenine nucleus, preferably having a nitro or cyano substituent, e.g., 3,3-dimethyl-5 or 6-nitroindolenine, 3,3- dimethyl-S- or 6-cyanoindolenine, etc.; and, an imidazole nucleus, e.g., imidazole, l-alkylimidazole, 1-alkyl-4-phenylimidazole, 1-alkyl-'4,S-dimethylirnidazole, benzimidazole, 1 alkylbenzimidazole, 1 alkyl-S-nitrobenzimidazole, 1- aryl 5,6 dichlorobenzimidazole, l-alkyl-u-naphthimidazole, 1 aryl B-naphthimidazole, 1-alkyl-5-methoxy-anaphthimidazole, or, an imidazo[4,5-b]quinoxaline nucleus, e.g., l-alkylimidazo[4,5-b]quinoxaline such as 1- ethylimidazo [4,5-b] -quinoxaline, 6-chlorol-ethylimidazo- [4,5-b1quinoxaline, etc., l-alkenylimidazo [4,5-b] quinoxaline such as 1-allylimidazo[4,5-b]-quinoxaline, 6-ch1oro- 1 allylimidazo[4,5-b]quinoxaline, etc., l-arylimidazo- [4,5-b]quinoxaline such as l-phenylimidazo[4,5-b]quinoxaline, 6 chloro 1-phenylimidazo[4,5-b]quinoxaline, etc.; a 3,3-dialkyl-3H-pyrrolo[2,3-b] pyridine nucleus, e.g., 3,3 dimethyl-3H-pyrrolo[2,3-b]pyridine, 3,3-diethyl-3H- pyrr01o[2,3-b] pyridine, etc.; a thiaZolo[4,5-b]quino1ine nucleus; an indolyl nucleus including substituted indolyl nuclei such as a 2-phenyl-3 indole, 1-methyl-2-phenyl-3- indole; and the like; R represents an alkyl group, including substituted alkyl (preferably a lower alkyl containing from 1 to 4 carbon atoms), e.g., methyl, ethyl, propyl, isopropyl butyl, hexyl, cyclohexyl, decyl, dodecyl, etc., and substituted alkyl groups (preferably a substituted lower alkyl containing from 1 to 4 carbon atoms), such as a hydroxyalkyl group, e.g., fi-hydroxyethyl, w-hydroxybutyl, etc., an alkoxyalkyl group, e.g., B-methoxyethyl, wbutoxybutyl, etc., a carboxyalkyl group, e.g. p-carboxyethyl, w-carboxybutyl, etc., an alkoxy group, e.g., methoxy, ethoxy, etc. a sulfoalkyl group, e.g., fl-sulfoethyl, w-sulfobutyl, etc., a sulfatoalkyl group, e.g., fi-sulfatoethyl, wsulfatobutyl, etc., an acyloxyalkyl group, e.g., fl-acetoxyethyl, 'y-acetoxypropyl, w-butyryloxybutyl, etc., an alkoxycarbonylalkyl group, e.g., p-methoxycarbonylethyl, wethoxycarbonylbutyl, etc. or an aralkyl group, e.g., benzyl, phenethyl, etc.; an alkenyl group, e.g., allyl, l-propenyl, 2-butenyl, etc., or an aryl group, e.g., phenyl, tolyl, naphthyl, methoxyphenyl, chlorophenyl, etc.; Q represents the non-metallic atoms required to complete a 5 to 6 membered heterocyclic nucleus, typically containing a hetero atom selected from nitrogen, sulfur, selenium, and oxygen, such as a 2-pyrazolin-5-one nucleus (e.g., 3- methyl 1 phenyl 2-pyrazolin-5-one, 1-pheny1-2-pyrazolin-S-one, 1 (2 benzothiazolyl) 3-methyl-2-pyrazolin-S-one, etc.); an isoxazolone nucleus (e.g., 3-phenyl 5 (4H) isoxazolone, 3-methyl-5-(4H)-isoxazolone, 3- methyl 5 (4H)-isoxazolone, etc.); an oxindole nucleus (e.g., 1-alkyl-2,3-dihydro-2-oxindoles, etc.), a 2,4,6-triketohexahydropyrimidine nucleus (e.g., barbituric acid or 2-thiobarbituric acid as well as their l-alkyl (e.g., 1- methyl, l-ethyl, l-propyl, l-heptyl, etc.) or 1,3-dialkyl (e.g., 1,3 dimethyl, 1,3 diethyl, 1,3-dipropyl, 1,3-diisopropyl, 1,3 dicyclohexyl, 1,3 di(fi-methoxyethyl), etc.) or 1,3-diaryl (e.g., 1,3-diphenyl, 1,3-di(p-chlorophenyl), 1,3 di(p-ethoxycarbonylphenyl), etc.) or l-aryl (e.g., 1- phenyl, l-p-chlorophenyl, l-p-ethoxycarbonylphenyl), etc.) or l-alkyl-S-aryl (e.g., 1-ethyl-3-phenyl, l-n-heptyl- 3-phenyl, etc. derivatives), a rhodanine nucleus (i.e., 2- thio-2,4-thiazolidinedione series), such as rhodanine, 3- alkylrhodanines (e.g., 3-ethylrhodanine, 3-allylrhodanine, etc.), 3-carboxyalkylrhodanines (e.g., S-(Z-carboxyethyD- rhodanine, 3 (4-carboxybutyl)rhodanine, etc.), 3-sulfoalkylrhodanines (e.g., 3-(2-sulfoethyl)rhodanine, 3-(3- sulfopropyl)rhodanine, 3 (4-sulfobutyl)rhodani11e, etc.), or 3-arylrhodanines (e.g., B-phenylrhodanine, etc.), etc.; a 2(3H)-imidazo[1,2-a]-pyridone nucleus; a Z-furanone nucleus (e.g., 3-cyano-4-phenyl-2(5H)-furanone); a thiophen-3-one-l,1-dioxide nucleus (e.g., benzo[b]thiophen- 3(2H) one-1,1-dioxide); a 5,7-dioxo-6,7-dihydro-5-thiazolo[3,2-a]-pyrimidine nucleus (e.g., 5,7-dioxo-3- phenyl 6,7 dihydro-S-thiazolo[3,2-a]pyrimidine, etc.); a 2- thio-2,4-oxazolidinedione nucleus (i.e., those of the 2-thio- 2,4-(3H,5H)-oxazoledione series) (e.g., 3-ethyl-2-thio- 2,4 oxazolidinedione, 3-(2-sulfoethyl)-2-thio-2,4-oxazolidinedione, 3 (4-sulfobutyl)-2-thio-2,4-oxazolidinedione, 3 (3 carboxypropyl)-2-thio-2,4-oxazolidinedione, etc.); a thianaphthenone nucleus (e.g., 2-(2H)-thianaphthenone, etc.); a 2-thio-2,5-thiazolidinedione nucleus (i.e., the 2- thio 2,5 3H,4H) thiazoledione series) (e.g., 3-ethyl-2- thio-2,S-thiazolidinedione, etc.); a 2,4-thiazolidinedione nucleus (e.g., 2,4-thiazolidinedione, 3-ethyl-2,4-thiazolidinedione, 3 phenyl-2,4-thiazolidinedione, 3-a-naphthyl- 2,4 thiazolidinedione, etc.); a thiazolidinone nucleus (e.g., 4-thiazolidinone, 3-ethyl-4-thazolidinone, 3-phenyl- 4-thiazolidinone, 3-a-naphthyl-4-thiazolidinone, etc.), a 2- thiazoline-4-one series (e.g., Z-ethylmercapto-Z-thiazolin- 4-one, 2-alkylphenylamino-2-thiazolin-4-one, 2-diphenylamino-2-thiazolin-4-one, etc.); a 2-imino-4-oxazolidinone (i.e., pseudohydantoin) nucleus; a 2,4-imidazolidinedione (hydantoin) series (e.g., 2,4-imidazolidinedione, 3-ethyl- 2,4 -imidazo1idinedione, 3-phenyl-2,4-imidazolidinedione, 3 a naphthyl-2,4-imidazolidinedioue, 1,3-diethyl-2,4- imidazolidinedione, 1 ethyl 3phenyl-2,4-imidazolidinedione, 1 ethyl 2-a-naphthyl-2,4-imidazolidinedione, 1,3-diphenyl-2,4-imidazolidinedione, etc.), a 2-thio-2,4- imidazolidinedione (i.e., 2-thiohydantoin) nucleus (e.g.,

8 2-thio-2,4-imidazolidinedione, 3 ethyl 2-thio-2,4-imidazolidinedione, 3 (4 sulfobutyl)-2-thio-2,4-imidazolidinedione, 3 (Z-carboxyethyl)-2-thio-2,4-imidazolidinedione, 3 phenyl 2-thio-2,4-imidazolidiuedione, 3-anaphthyl 2 thio-2,4-imidazolidinedione, 1,3-diethyl-2- thio 2,4 imidazolidinedione, l-ethyl-3-phenyl-2-thi0-2,4- imidazolidinedione, 1 ethyl 3- -naphthyl-2-thio-2,4- imidazolidinedione, 1,3 diphenyl 2-thio-2,4-imidazolidinedione, etc.), a Z-imidazolin-S-one nucleus (e.g., 2- propylmercapto-2-imidazol-iu-5-one, etc.)

n is a positive integer from 1 to 4; m is a positive integer from 1 to 3; g is a positive integer from 1 to 2;

R and R each represent a cyano radical, an ester radical such as ethoxycarbonyl, methoxycarbonyl, etc., or an alkylsulfonyl radical such as ethylsulfonyl, methylsulfonyl, etc.;

L represents a methine linkage having the formula wherein T is hydrogen, lower alkyl of 1 to 4 carbon atoms or aryl such as phenyl, e.g., CH=, C(CH C(C6H5)=, etc.;

D, E, J, R and R each represent a hydrogen atom, an alkyl group (preferably a lower alkyl containing from 1 to 4 carbon atoms), e.g., methyl, ethyl, propyl, isopropyl, butyl, decyl, dodecyl, etc., or an aryl group, e.g., phenyl, tolyl, naphthyl, methoxyphenyl, chlorophenyl, nitrophenyl, etc.;

X represents an acid anion, e.g., chloride, bromide, iodide, perchlorate, tetrafluoroborate, sulfamate, thiocyanate, p-toluenesulfonate; methyl sulfate, etc.;

G represents an anilino radical or an aryl radical, e.g., phenyl, naphthyl, dialkylaminophenyl, tolyl, chlorophenyl, nitrophenyl, anilinovinyl, etc.;

R is an alkyleneoxy radical having 1 to 8 carbon atoms in the alkylene chain including an alkylenedioxy radical and an arylenebisalkoxy radical e.g., ethyleneoxy, trimethyleneoxy, tetramethyleneoxy, propylideneoxy, ethylenedioxy, phenylenebisethoxy, etc.;

R represents either (1) an alkyl radical including a substituted alkyl (preferably a lower alkyl having 1 to 4 carbon atoms), e.g., methyl, ethyl, propyl, isopropyl, butyl, hexyl, cyclohexyl, decyl, dodecyl, aralkyl such as benzyl, sulfoalkyl such as fi-sulfoethyl, w-sulfobutyl, wsulfopropyl; or (2) an acyl radical, e.g.,

wherein R is an alkyl including a substituted alkyl or an aryl radical such as methyl, phenyl, naphthyl, propyl, benzyl, etc.

In the above formulae Q preferably completes a pyridine, an indole or a quinoline nucleus. Also, D, E and J are preferably aryl radicals. Nuclei wherein Q Q Q Q and Q complete an imidazo [4,5-b]quinoxaline nucleus, or a nitro group thiazole, oxazole, selenazole, thiazoline, pyridine, quinoline, indole, or imidazole nucleus are referred to hereafter as desensitizing nuclei.

Typical compounds and intermediates included in the scope of this invention are the following:

1. 3-ethyl-1-methoxyoxa-2'-pyridocarbocyanine perchlorate 2. 1'-ethoxy-3-ethyloxa-2-pyridocarbocyanine tetrafiuoroborate 3. 3-ethy1-1-methoxy-2-pyridothiacyanine iodide 4. 1-ethoXy-3'-ethyl-2-pyridothiacyanine tetrafluoroborate 5. 1-benzyloxy-3'-ethyl-2-pyridothiacyanine iodide 6. 3'-ethyl-1-methoxy-Z-pyridothiacarbocyanine iodide 7. 1-ethoxy-3'-ethyl-Z-pyridothiacarbocyanine tetrafiuoroborate 8. anhydro-3 '-ethyl-1-(3-sulfopropoxy)-2-pyridothiacarbocyanine hydroxide 9. 1-benzyloxy-3-ethyl-2'-pyridothiacarbocyanine perchlorate 10. 3'-ethyl-1-methoxy-2-pyridothiacarbocyanine perchlorate 11. 1-meth0xy-1,3,3-trimethylindo-2'-pyridocarbocyanine picrate 12. 3-ethyl-1-methoxy-4,5'-benzo-2-pyridothiacarbocyanine perchlorate 13. 1-ethoxy-3'-ethyl-4,5-benzo-2-pyridothiacarbocyanine tetrafluoroborate 14. 1'-ethoxy-3-ethyloxa-2-carbocyanine tetrafluoroborate 15. 1'-ethoxy-3-ethylthia-2'-cyanine tetrafiuoroborate 16. 1'-ethoxy-3-ethylthia-2'-carbocyanine tetrafluoroborate 17. 1-ethoxy-3-ethylthia-2-dicarbocyanine tetrafiuoroborate 18. 1-methoxy-3'-methyl-2-pyridothiazolinocarbocyanine perchlorate 19. 3'-ethyl-1methoxy-4-pyridothiacyanine perchlorate 20. 3-ethyl-1-methoxy-4-pyridothiacarbocyanine perchlorate 21. 1,1-dimethoxy-2,2'-diphenyl-3,3'-indolocarbocyanine perchlorate 22. l-methoxy-1'-methyl-2,2',10-triphenyl-3,3'-indolocarbocyanine perchlorate 23. 1,1'diethoxy-2,2-diphenyl-3,3'-indolocarbocyanine perchlorate 24. 1-ethoxy-1'-methyl-2,2',10-triphenyl-3,3-indolocarbocyanine perchlorate 25. 1'-ethoxy-3-ethyl-4,5-benzothia-2-carbocyanine tetrafluoroborate 26. 2-B-anilinovinyl-l-methoxypyridinium p-toluenesulfonate 27. l-ethyl-1'-methoxy-4,S-benzothia-4-carbocyanine perchlorate 28. 3-ethyl-1-methoxy-6-nitro-2-phenyl-3-indolothiacarbocyanine p-toluenesulfonate 29. 1-ethoxy-3'-ethyl-6-nitro-2-phenyl-3-indolothiacarbocyanine p-toluenesulfonate 30. 1,3-diallyl-l-methoxy-2'-phenylimidazo[4,5-b]- quinoxalino-3'-indolocarbocyanine perchlorate 3 1. 1,3-diallyl-1'-ethoxy-2-phenylimidazo [4,5-b]- quinoxalino-3'-indolocarbocy-anine perchlorate 32. 1-methoXy-Z-methyIpyridinium p-toluenesulfonate 33. 1-methoXy-4-methylpyridinium p-toluenesulfonate 34. anhydro-Z-methyl-1(3-sulfopropoxy)pyridinium hydroxide 35. 1-ethoxy-2-methylpyridinium tetrafiuoroborate 36. 1-benzyloxy-Z-methylpyridinium bromide 37. 1-ethoxy-2-methylquinolinium tetrafiuoroborate 38. 1-methoxy-2-phenylindole 39. I-ethoxy-Z-phenylindole 40. 1-methoxy-1,3,3-trimethyl-5-nitro-2'-phenylindo- 3'-indolocarbocyanine perchlorate 41. 1-methoxy-1',3',3'-trimethyl-2-phenyl-3-indolo- 2-pyrrolo[2,3-b]pyridocarbocyanine perchlorate 42. 1'-ethoxy-l,3,3-trimethyl5-nitro-2'-phenylindo- 3'-indolocarbocyanine p-toluenesulfonate 43. 1-ethoxy-1,3',3-trimethyl-2-phenyl-3-indolopyrrolo- [2,3-b]pyridocarbocyanine perchlorate 44. 1,1'-ethylenedioxybispyridinium dibromide 45. 1,l'-trimethylenedioxybispyridiniurn dibromide 46. 1,1'-tetramethylenedioxybis(Z-methylpyridinium)- dibromide 47. 1,1-tetramethylenedioxybis(4-methylpyridinium)- dibromide 48. 1,1-tetramethylenedioxybispyridinium dibromide 49. 1,1'-pentamethlenedioxybispyridinium dibromide 50. 1-methoxy-2-phenylindole-3-carboxaldehyde The novel compounds of this invention are prepared by various methods. The following examples demonstrate some of the techniques that can be used. Indicated melting points are C.

EXAMPLE 1 Preparation of Compound 32 (Method A) A mixture of 2-picoline-N-oxide (10.9 g., 0.1 mole) and methyl p-toulenesulfonate (27.9 g., 0.1 mole+50%) is heated on a steam bath, with constant stirring, until an exothermic reaction starts. The heating is stopped and the temperature rises to a maximum of about The mixture is allowed to cool, diluted to 200 ml. with acetone and chilled. The solid which separates is collected and washed with acetone. The yield is 23.2 g. (79%), mp. 1134 C.

EXAMPLE 2 Preparation of Compound 36 (Method B) 2-Picoline-N-oxide (10.9 g., 0.1 mole) and benzyl bromide (18.8 g., 0.1 mole+10%) are dissolved in acetone (25 ml.) and the mixture is heated at reflux for 10 minutes. After dilution to ml. with acetone, the mixture is allowed to cool. The solid preciptate is collected and washed with acetone. The yield is 19.0 g. (68%), mp. 1134.

EXAMPLE 3 Preparation of Compound 26 Compound 32 (5.90 g., 0.02 mole) and ethyl isoformanilide (2.98 g., 0.02 mole) in dimethyl formamide (5 ml.) are heated on a steam bath for /2 hour. The mixture is diluted with acetone (50 ml.) and chilled. The yellow solid which separates is collected and washed with acetone. The yield is 3.3 g. (41%), mp. 172-3".

EXAMPLE 4 Preparation of Compound 1 3-Ethyl-1'-methoxyoxa-2'-pyridocarbocyanine perchlorate 0 L CH=CHCHJ N 6MB 010.- N/

l-Methoxy 2 methylpyridinium p toluenesulfonate (2.22 g., 1 mol.-+50%), 2-18-acetanilidovinyl- 3 ethylbenzoxazolium iodide (2.17 g., 1 mol.) and trirnethylamine (1.41 ml., 1 mol.+100%) in ethanol (20 ml.) are heated at reflux for 2 minutes. Then a solution of sodium perchlorate (0.61 g., 1 mol.) in hot methanol is added. After chilling, the solid is collected and washed with ethanol. Yield 1.50 g. (77%), m.p. 146-7".

11 EXAMPLE Preparation of Compound 3 3'-Ethyl-1-methoxy-Z-pyridothiacyanine iodide Preparation of Compound 6 3-Ethyl-1-methoxy-2-pyridothiacarbocyanine iodide l-Methoxy 2 methylpyridinium p-toluenesulfonate (2.22 g., 1 mol.+50%), Z-fi-acetanilidovinyl 3 ethylbenzothiazolium iodide (2.25 g., 1 mol.) and triethylamine (1.4 ml., 1 mol.+100%) in ethanol ml.) are heated at reflux for 2 minutes. The mixture is chilled and the solid which separates is collected and washed with ethanol. Yield 1.27 g. (58%), m.p. 115.

EXAMPLE 7 Preparation of Compound 10 3'-Ethyl-1-methoxy-2-pyridothiadicarbocyanine perchlorate CH=CHCH=CHCH= I OMe N Preparation of Com-pound 11 1'-Methoxy-1,3,3-trimethylindo-2'-pyridocarbocyanine picrate OzN NO:

I NC:

1-Methoxy 2 methylpyridinium p-toluenesulfonate (2.22 g., 1 mol.+50%), Z-fi-acetanilidovinyl 1,3,3 trimethyl-3H-indolium iodide (2.23 g., 1 mol.), triethylamine (1.4 ml., 1 mo1.+%) in ethanol (20 m1.) are heated at reflux for 2 minutes. The solution is cooled and a solution of picric acid (1.15 g., 1 mol.) in ethanol added. After chilling, the solid is collected and washed with ethanol. Yield 1.12 g. (40%).

EXAMPLE 9 Preparation of Compound 12 3'-Ethy1-1-methoxy-4',5'-benzo-2-pyridothia carbocyanine perchlorat l-Methoxy 2 methylpyridinium p-toluenesulfonate (2.22 g., 1 mol.+50% 2-,B-auilinovinyl-l-ethylnaphtho- [1,2-d]thiazolium p-toluenesulfonate (2.57 g., 1 mol.) and triethylamine (1.4 ml., 1 mol.+100%) in acetic anhydride (25 ml.) are warmed to 40 and stirred for 5 minutes. The small amount of undissolved solid is removed by filtration and the filtrate diluted with excess ether. The othe layer is decanted and the residue dissolved in methanol (25 ml.). A solution of sodium perchlorate (0.61 g., 1 mol.) in methanol is added. After chilling, th solid is collected and washed with methanol. Yield 1.48 g. (65%), m.p. indistinct.

EXAMPLE 10 Preparation of Compound 21 1,1'-Dimethoxy-2,2'-diphenyl3,3'-indolocarbocyanine perchlorate EXAMPLE 11 Preparation of Compound 22 l-Methoxy- '-methyl-2,2',10-triphenyl-3,3'-indol0- carbocyanine perchlorate 3-Formyl-1-methoxy-2-phenylindole (1.26 g., 1 mol.) and 1-methyl-2-methylenebenzyl-2-phenylindole (1.55 g., 1 mol.) are dissolved in hot acetic acid (10 ml.). 60% HClO (1.0 ml.) in acetic acid (3 ml.) is added and the mixture allowed to cool. After two hours at room temperature, the solid is collected and Washed with methanol and ether. After recrystallization from methanol acidified with I-IClO the yield of purified dye is 1.92 g. (59% m.p. 2589 C.

EXAMPLE 12 Preparation of Compound 28 3-Ethyl-1-methoxy-6-nitro-2-phenyl-3-indolothiacarbocyanine p-toluenesulfonate 3-Formyl-l-methoxy-Z-phenylindole (1.26 g., 1 mol.), 3-ethyl-2-methyl-6-nitrobenzothiazolium p toluenesulfonate (1.98 g., 1 mol.) and acetic anhydride (10 ml.) are heated at reflux for 1 minute. After cooling, excess ether is added slowly. The solid is collected and washed with ether. After recrystallization from methanol acidified with p-toluenesulfonic acid, the yield of purified dye is 2.64 g. (84%).

EXAMPLE 13 Preparation of Compound 30 1, 3-Dia1lyl-1'-methoxy-2-phenylimidazo [4, -b] -quinoxalino 3'-indolocarbocyanine perchlorate CHzCH=CH2 This dye is prepared in the manner described in Example 31, except that 1,3-diallyl-2-methylimidazo[4,5-b] quinoxalinium p-toluenesulfonate (2.18 g., 1 mol.) is used in place of 3-ethyl-2-methyl-G-nitrobenzothiazolium ptoluenesulfonate. After recrystallization from a mixture of acetonitrile (65 ml.) and 60% HClO (1.0 ml.), the yield of purified dye is 1.78 g. (60% m.p. 229-3l C.

EXAMPLE 14 Preparation of Compound 38 l-Methoxy-Z-phenylindole Sodium (3.0 g., 1 mol. l 30%) is dissolved in methanol (200 ml.). 1-Hydroxy-2-phenylindole (20.9 g., 1 mol.) [Fischer, Ber. 28; 585 (1895) and Ber. 29, 20.63 (1896)] and methyl iodide (25.6 g., 1 mol. 80%) are added, and the mixture refluxed for 1 hour. The solution is chilled, and the solid which separates is collected and washed with methanol. Yield 15.9% g. (71%), m.p. 5l2 C.

EXAMPLE 15 Preparation of Compound 40 1-Methoxy-1,3,3-trimethy1-5 -nitro-2'-phenylindo- 3'-indolocarbocyanine perchlorate Me Ma Q H No: Me() N CH=C W. Ph

Me C104- 3-Formyl-l-methoxy-Z-phenylindole (1.26 g., 1 mol.), l,2,3,3-tetramethyl 5-nitro-3H indolium p-toluenesulfonate (1.30 g., 1 mol.) and acetic anhydride (10 ml.) are heated at reflux for 1 minute. After cooling, excess ether is added. The ether layer is decanted, the viscous residue dissolved in methanol (25 ml.) and 60% HClO (1.0 ml.) in MeOH (5 ml.) added. The mixture is chilled and the solid collected and washed with methanol. After recrystallization from a mixture of methanol and acetonitrile, the yield of purified dye is 1.20 g. (43%), m.p. 266 C.

EXAMPLE 16 Preparation of Compound 41 l-Methoxy-l 3 3 '-trimethyl-2-phenyl-3-indolo-2- pyrrolo[2,3-b] pyridocarbocyanine perchlorate Me Me Q MeON CH=CH g A Me 0104- 3-Forrnyl-l-methoxy-Z-phenylindole (1.26 g., 1 mol.), 1,3,3-trimethyl-2-methylene 2,3-dihydropyrrolo[2,3-b] pyridine (0.87 g., 1 mol.), p-toluenesulfonic acid monohydrate (0.95 g., 1 mol.) and acetic anhydride (10 ml.) are heated at reflux for 1 minute. The mixture is allowed to cool, diluted with ether, and the ether layer decanted. The residue is dissolved in methanol (25 ml.) and 60% HClO (1.0 ml.) in 5 ml. methanol added. After chilling, the solid is collected and Washed with methanol. After one recrystallization from acetonitrile, the yield of purified dye is 1.78 g. (69%), m.p. 235-9" C.

EXAMPLE 17 Preparation of Compound 50 3-Formyl-l-methoxy-Z-phenylindole Phosphoryl chloride (5.2 ml., 1 mol. 10%) is added slowly to dimethyl formamide (15 ml.), with cooling, so that the temperature does not exceed 20. A solution of l-methoxy-Z-phenylindole (11.15 g., 1 mol.) in dimethyl formamide (30 ml.) is added slowly, while keeping the temperature below 25 The mixture is warmed at 40 for 45 minutes, then poured into ice water (390 ml). 5N NaOH (70 ml.) is added, and a viscous mass separated. The mixture is heated to 65 and the lumps broken up. The solid is collected and washed with water. The yield is 11.95 g. (96%), m.p. 116-7", unchanged after recrystallization from ethanol.

The same general methods of preparation set forth in Examples 1-17 are used for the synthesis of additional compounds. The compound prepared, method, solvent, yield and melting points for these compounds are set forth in the following tables.

TABLE I Melting Yield point, Solvent (percent) degrees 43 Decomposes. 33 Do. 18 125-30. 89 Deeomposes. 45 128-31. 45 125. 81 Deeomposes. 38 143. 47 Decomposes. 63 138-9. 35 127-8. 20 186-7. 58 128. 36 219-21. 55 205-9. 40 Decomposes. 100 D0. 13 58 220-1. 15 (no NaOl added). 65 194-200 16 dO 69 237-41 1 Reaction mixture diluted with acetone to precipitate dye. Reaction temperature 25, no NaClOi added.

TABLE II Melting Cpd. Yield point, N 0. Base Alkylating agent Method Solvent (percent) degrees 33 4picoline-N0xide Methyl p-toluenesulfonate A 97 153-4 34 Z-picoline-N-oxide. 1,3-propanesultone B 95 202-3 35 ..do Triethyloxonium tetrafluoroborate. B 80 53-7 37 Quinaldine-N-oxide ..do B 90 115-7 39 1-hydroxy-2-phenylindol- Ethyl iodide Ex. 14 100 Oil 44 Pyridine-N-oxide 1,2-dibromoethane.... A 81 170-1 45 do 1,3-dibromopr0pane A 100 151-3 46 2-picoline-N-0xide-.. 1,4-dibromobutane A 88 153-4 47 4-picoline-N-oxide d B 39 109-11 48 Pyridine-N-oxirle do A 91 172 49 do 'bromopen no A 33 115-7 51 1-ethoxy-2-phenylind Ex. 17 98 95-6 EXAMPLE 50 they receive. The bleaching results from the fragmenta- 1,3-Diethyl--[ 1-methoxy-2( 1H -pyridylidene ethylidene]-2-thiobarituric acid [1 C) Et N CH-CH- =S N --N Me Z-B-anilinovinyl-l-methoxypyridinium p toluenesulfonate (3.99 g., 1 mol.) 1,3-diethyl-2-thiobarituric acid (2.00 g., 1 mol.) and acetic anhydride ml.) are stirred together as triethylamine (5 ml.) is added. The mixture is stirred for a few minutes until all the solid is dissolved. A seed crystal is added [obtained by dilution of a small portion of reaction mixture with excess ether] and the mixture chilled a few hours. The solid dye is collected and washed, first with methanol, then with ether. The yield of dye is 1.48 g. (44%), mp. 171-2 dec.

The following compounds are prepared in the same manner as compound 54 is Example 50. The compound prepared, yield and melting points are set forth in Table III below.

TABLE III Melting Cpd. Yield poin Ex. No. No. (percent) C.)

51 55 47 75.5. 52--. 56 154-5. 53.-- 57 73 Decomposes. 54 58 79 169-70. 55 59 88 1,334.

In order to provide a better understanding of the many facets of the invention, several applications will be discussed in detail. While the novel compounds described hereinbefore are useful in the various embodiments set forth below, preferred ones are described.

tion of the dye molecule, fragmentation being caused, at least in part, by the cleavage of the NO linkage. Thus, when the dyes are coated on or imbibed into a suitable support and exposed in an imagewise manner, direct positive reproductions are obtained. The advantages of this process are numerous, e.g., no chemical development is necessary nor is there any need for any other material in the coating composition other than the dye itself. Since the dyes of the invention are of different colors, images having various colors can be made. For coating purposes, it is often convenient to disperse the dye in a film-forming binder. Useful binders include those which are commonly used in preparing photographic elements.

While generally all of the compounds encompassed by formulae A through H are suitable in preparing photobleach images, the preferred ones have the following structure:

17 wherein:

R, R R R R L, Q Q X, G, n, g and m are each defined above. Typical compounds exemplary of the above include compounds 1-13, 18, 26, 52 through 59.

Since these bleachable dyes are of various colors, as explained previously, they can be used in the production of direct positive color prints. Thus, when a white substrate is coated with a layer of a yellow dye, a layer of a magenta dye and a layer of a cyan dye and the resultant element is exposed to White light through a color transparency, a direct positive color print is obtained. The three dyes need not be present as separate layers but may be in a uniform admixture. The color image is obtained by virtue of the fact that these dyes are bleached when exposed to a light source of substantially the same wavelength which they absorb. Since yellow absorbs blue, where light in the blue region strikes the yellow layer, the yellow layer bleaches and becomes colorless. .Si-milar effects are observed in the other two layers, magenta absorbing green and bleaching and cyan absorbing red and bleaching in proportions to the exposure received. The result of the process is a right-reading color reproduction of the color original. Such a process is generally known in the art, and is more fully described in US. 3,104,973 (Sprague et al.).

EXAMPLE 56 A solution of 46.1 mg. of compound 12 (magenta), 43.7 mg. of compound (cyan) and 39.8 mg. of compound 4 (yellow) in 50 g. of 20% poly-(2-vinylpyridine) binder is prepared by rotary mixing. After two hours mixing 1.46 g. of triethanolamine is added and the solution is mixed for an additional two hours. The solution is then coated on a white pigmented cellulose acetate base at a thickness of 0.002 in. After drying, the elements are exposed through a color positive transparency with a high intensity flash lamp. Instant color positives are obtained.

THERMOGRAPHIC COPYING The dyes of the invention (i.e., formulae A-H) can be used to prepare thermographic copy elements. As explained previously, the compounds of this invention fragment when subjected to various forms of energy. Accordingly, when these compounds are exposed to heat, fragmentation occurs. The compounds lose their original color and generally are bleached. Because of this feature, they can be used in thermographic copy sheets as the heat-sensitive material. Dyes of formula E are preferred.

The compounds forming the heat-sensitive areas of a copy sheet can be coated on or imbibed into any suitable support (especially supports having low thermal conductivity). In general, ordinary paper can be used as a support for the heaflsensitive composition and the paper can be transparent, translucent or opaque. It is frequently desirable to use a support which transmits the exposing radiation, especially where the original does not transmit such radiation (i.e., at least one of these should transmit such radiation). Advantageously, a paper or other fibrous material can be employed which has a charn'ng temperature above about 125 C.

In preparing thermographic elements of this invention, the heat-sensitive dye is usually coated on a translucent or opaque support. After a period of drying, the heat-sensitive, copying sheet can then be placed in contact with an original containing line copy, such as typewritten characters, and exposed to infrared radiation. The portions of the original which are highly absorptive of the infrared radiation convert the radiation to heat which is conducted to the copying material producing a rapid color change in those portions of the copying sheet which are in heat-conductive relationship with the original. The portions of the copying sheet which are not in heat-conductive relationship with the original, transmit or reflect the infrared radiation so that no color change occurs.

If desired, the heat-sensitive compounds of the invention can be dispersed in a binding material and the entire composition coated on the surface of the support. Suitable binding agents include ethyl cellulose, polyvinyl alcohol, gelatin, collodion, polyvinyl acetal, cellulose esters, hydrolyzed cellulose esters, etc. When a colloidal binding agent is employed, the amount thereof used can be varied in order to vary the contrast of the resulting copy. These effects are well understood by those skilled in the art. Various esthetic effects may be produced by adding inert pigments or colorants to the colloidal dispersions, although there is generally no advantage to be gained by the use of such materials. In some instances, an apparent increase in contrast can be obtained by using a coloring pigment in the colloidal binding material.

The source of infrared radiation can be arranged so that the rear surface of the original receives the infrared radiation, although in such cases it may be convenient to have an insulating surface applied to the rear surface of the original in order to localize and intensify the heat received by the original. Alternatively, the heat-sensitive layer of the copying material can be placed in contact with the printed characters of the original and the assembly then exposed either from the rear side of the original or the rear side of the copying sheet. These adaptations are well understood by those skilled in the art and are illustrated in domestic and foreign patents. See for example, Miller US. Pat. 2,663,657, issued Dec. 22, 1953.

Exposure of the thermographic element can be accomplished by reflex (as explained above) or by bireflex techniques. According to the latter method, a support for such an exposure should be readily permeable to radiant energy, such as infrared radiation. Also, the support is advantageously relatively thin so that the heat generated in the printed characters of the original can be transmitted to the heat-sensitive layer thereby causing a color change to take place in a pattern corresponding to the printed characters. If desired, the support can be ordinary paper which has been transparentized temporarily, so that exposure can be made as described. The transparentizing substance can then be removed after exposure to provide an opaque reflecting support. Such transparentizing treatment is well known to those skilled in the art.

It has also been found that the application of the heatsensitive layer to the support need not be done in a uniform manner, but that the heat-sensitive layer can be applied non-uniformly in a regular pattern, such as lines or dots. Such coatings can be used for special purposes, such as in the graphic arts field.

While only an infrared lamp has been discussed as the exposing source, it is to be understood that other sources of radiant energy can conveniently be employed in the described thermographic process. Advantageously, the source of radiation is selected so that it is strongly absorbed by the characters or printed materials being reproduced. Thus, the characters absorb the radiant energy and transform it into heat which is transmitted to the heatsensitive coating. Incandescent bodies can conveniently be employed as the source of radiant energy, since such incandescent material is generally rich in the radiant energy absorbed by many of the printing materials currently being used. Where the radiant energy is not transmitted by the support bearing the heat-sensitive material, the material being copied should transmit such radiant energy so that exposure can be made through the rear surface of the material bearing the printed characters.

While any of the compounds within the scope of formulae A-H are operable in the novel heat-sensitive elements described herein, compounds 1-53 are preferred.

EXAMPLE 57 A paper support is coated with a layer of a composition containing gelatin and compound 12. A graphic original having printed material thereon is placed in contact with the uncoated surface of the paper. Upon exposure of the assembly to infrared radiation supplied by an infrared lamp, a fascimile copy of the printed characters of the printed characters of the original is obtained.

EXAMPLE 8 A composition containing compound 32 in gelatin is coated on an aluminum base. The element is written on with a hot stylus on the noncoated side. A good image is recorded in the heated areas.

LIGHT-SCREENING LAYERS The dyes described herein have been found to be useful in light-screening layers, including antihalation and filter layers, in photographic light-sensitive elements employing one or more sensitive silver halide layers. They can be incorporated readily in colloidal binders used for forming such layers or they can be coated without the aid of a vehicle. They are especially useful in gelatin layers adjacent to the silver halide layers and also in dry processes. The dyes can be readily bleached without the need for removing the layers containing them. Bleaching of the dyes occurs when the layer containing them is subjected to some form of energy, e.g., light or heat. The energy causes the compound to fragment and become colorless, as explained previously.

These dye compounds can be mordanted in layers coated in contact with light-sensitive silver halide emulsion layers since the mordanted dyes have very good stability at the pH of most sensitive silver halide emulsions and have little or no undesirable effect on the silver halide. Also, the dyes can be used as light-screening dyes in layers coated directly on top of sensitive silver halide emulsion layers or between two sensitive silver halide emulsion layers or between the support and a sensitive silver halide emulsion layer or on the back of the support as an anti halation layer. The elements in which these materials are used as screening layers can contain either the conventional developing-out silver halide emulsions or light-developable silver halide emulsions such as those described in Ser. No. 481,918, filed Aug. 23, 1965, now U.S. Pat. No. 3,418,122 and Ser. No. 625,590, filed Mar. 24, 1967, now U.S. Pat. No. 3,447,927.

The light-screening layers of this invention are prepared by coating on the photographic element or on its support, by methods well known in the art, a solution of the dye, a hydrophilic colloid binder and a coating aid such as saponin. In addition to these materials, it is advantageous to add a mor'dant to this solution to render the dye nonwandering. For most purposes it is desirable to add agents to harden the colloidal binder material so that the lightscreening layer will remain intact in the photographic element during and following the processing operation. The pH of the coating solution is adjusted when necessary to a level that is compatible with the light-sensitive emulsion layer by the usual methods.

The proportions of the dye, colloidal binder, mordant, hardener, and coating aid used in making the light-screening layers can be varied over wide ranges and will depend upon the specific requirements of the photographic element being produced. The methods used to determine the optimum composition are well known in the art and need not be described here.

The light-sensitive layer or layers and the light-screening layer or layers of the photographic element can be coated on any suitable support material used in photography such as cellulose nitrate, cellulose acetate, synthetic resins, paper, metal, glass, etc.

Hydrophilic colloidal materials used as binders for light-screening dyes of the invention include gelatin, collodion, of carboxylated cellulose, hydroxy ethyl cellulose, carboxy methyl cellulose, carboxmethyl hydroxyethyl cellulose, synthetic resins, such as the amphoteric copolymers described by Clavier et al. in U.S. Pat. 2,949,442, issued Aug. 16, 1960, polyvinyl alcohol, and others well known in the art. The above mentioned amphoteric copolymers are made by polymerizing a monomer having the formula:

CHQZCR OOH wherein R represents an atom of hydrogen or a methyl group, and a salt of a compound having the general formula:

CH=CR CHzNHz wherein R has the above mentioned meaning, such as an allylamine salt. These monomers can further be polymerized with a third unsaturated monomer in an amount of 0 to 20% of the total monomer used, such as an ethylene monomer that is copolymerizable with the two principal monomers. The third monomer can contain neither a basic group nor an acid group and may, for example, be vinyl acetate, vinyl chloride, acrylonitrile, methacrylonitrile, styrene, acrylates, methacrylates, acrylamide, methacrylamide, etc. Examples of these polymeric gelatin substitutes are copolymers of allylamine and methacrylic acid; copolymers of allylamide, acrylic acid and acrylamide; hydrolyzed copolymers of allylamine, methacrylic acid and vinyl acetate; copolymers of allylamine, acrylic acid and styrene; the copolymer of allylamide, methacrylic acid and acrylonitrile; etc.

In preparing the light-screening layer composition, the dye is generally added to the water-permeable colloidal binder in water solution. In some instances it can be advantageous to form an alkali metal salt of the dye by dissolving the dye in a dilute aqueous alkali metal carbonate solution. Usually a coating aid, such as saponin is added to the dye colloidal suspension before coating it as a layer on the photographic element. The dye is advantageously mordanted with a suitable basic mordant added to the colloidal suspension before coating.

Mordants that can be used include the mordants described by Minsk in U.S. 2,882,156, issued Apr. 14, 1959, prepared by condensing a polyvinyl-oxo-compound such as a polyacrolein, a poly-'y-methylacrolein, a polyvinyl alkyl ketone such as polyvinyl methyl ketone, polyvinyl ethyl ketone, polyvinyl propyl ketone, polyvinyl butyl ketone, etc., or certain copolymers containing acrolein, methacrolein, or the above mentioned vinyl alkyl ketone components, for example, 1 to 1 molar ratio copolymers of these components with styrene or alkyl methacrylates wherein the alkyl group contains from 1 to 4 carbon atoms, such as methyl, ethyl, propyl, or butyl methacrylates in the proportions from about 0.25 to 5 parts by weight of the said polymeric oxo-compound with one part by weight of an aminoguanidine compound such as aminoguanidine bicarbonate, aminoguanidine acetate, aminoguanidine butyrate, etc.; the reaction products of polyvinylsulfonates with C-aminopyridines of Reynolds et al. U.S. 2,768,078, issued Oct. 23, 1956, prepared by reacting alkyl and aryl polyvinyl sulfonates prepared as described in U.S. 2,531,468 and U.S. 2,531,469 both dated Nov. 28, 1950, under controlled conditions with C-aminopyridines or alkyl group substituted C-aminopyridines such as 2-aminopyridine, 4-aminopyridine, the aminopicolines such as 2-amino-3-methylpyridine, 2-amino-4-methylpyridine, 2-amino-S-methylpyridine, 2-amino-6-methylpyridine and corresponding 4-aminomethyl derivatives which react in this reaction in exactly the same way, 2- amino-6-ethylpyridine, 2-amino-6-butylpyridine, 2-amino- 6-amylpyridine, etc.; the various aminotoluidines such as, for example, 2-amino-3-ethyl-4-methyl pyridine, etc.; the dialkylaminoalkyl esters of dialkylaminoalkylamides, e.g., such as those described by Carroll et al., U.S. Pat. 2,675,- 316, issued Apr. 13, 1954, prepared by reacting addition polymers containing carboxyl groups 'with a basic dialkylamino compound, for example, N-dialkylamine ethyl esters of polymers or copolymers containing carboxyl groups; the addition type polymers containing periodically occurring quaternary groups of Sprague et al. US. 2,548,- 564, issued Apr. 10, 1951, including quaternary ammonium salts of vinyl substituted azines such as vinylpyridine and its homologs such as vinyl quinoline, vinylacridine, and vinyl derivatives of other six-membered heterocyclic ring compounds containing hydrogen atoms. These addition polymers include 2-vinylpyridine polymer metho-ptoluenesulfonate, 4-vinyl-pyridine polymer metho-p-toluenesulfonate.

Hardening materials that can be used to advantage in the described light-screening layer include such hardening agents as formaldehyde; a halogen-substituted aliphatic acid such as mucobromic acid as described in White US. Pat. 2,089,019, issued May 11, 1937; a compound having a plurality of acid anhydride groups such as 7.8 diphenylbicyclo(2,2,2)-7-octene-2,3,5,6-tetra-carboxylic dianhydride, or a dicarboxylic or a disulfonic acid chloride such as terephthaloyl chloride or naphthalene- 1.5-disulfon vl chloride as described in Allen and Carroll, U.S. Pats. 2,725,294 and 2,725,295, both issued Nov. 29, 1955; a cyclic 1,2-diketone such as cyclopentane-1.2-dione as described in Allen and Byers, US. Pat. 2,725,305, issued Nov. 29, 1955; a biester of methanesulfonic acid such as 1,2-di(methanesulfonoxy)-ethane as described in Allen and Laakso, US. Pat. 2,726,162, issued Dec. 6, 1955; 1.3-dihydroxymethylbenzimidazoyl 2 one as described in July, Knott and Pollak, US. Pat. 2,732,316, issued Jan. 24, 1956; a dialdehyde or a sodium bisulfite derivative thereof, the aldehyde groups of which are separated by 23 carbon atoms such as [ft-methyl glutaraldehyde bis-sodium bisulfite as described in Allen and Burness US. Patent Application Ser. No. 556,031, filed Dec. 29, 1955, now abandoned; a bis-aziridine carboxamide such as trimethylene bis(1-aziridine carboxamide) as described in Allen and Webster US. Pat. 2,950,197, issued Aug. 23, 1960; or 2,3-dihydroxydioxane as described in Jeifreys, US. Pat. 2,870,013, issued Jan. 20, 1959.

Photographic elements utliizing these novel light-screening layers have li hbsensitive emulsion layers containing silver chloride, silver bromide, silver chlorobromide, silver iodide, silver bromoiodide, silver chlorobromoiodide, etc., as the light-sensitive material. The silver halide emulsions may be sensitized by any of the sensitizers commonly used to produce the desired sensitometric characteristics.

The dyes of this invention are valuable for preparing light-filtering layers for light-sensitive photographic elements containing silver halide emulsion layers. The lightfiltering layers containing these dyes are used to advantage, either over the light-sensitive silver halide emulsion layers, or between the light-sensiitve silver halide emulsion layer and the support, between two different light-sensitive layers, or as an antihalation backing layer.

EXAMPLE 59 A solution containing Compound 12 dissolved in a mixture of dimethylformamide and methyl alcohol is added to an aqueous gelatin solution. The mixture is agitated thoroughly to ensure complete and uniform mixing. The resultant solution is coated on a film support so that each square foot of support contains 300 mg. of gelatin and 240 mg. of dye. Superimposed on the thus formed filter layer is a conventional photographic silver halide emulsion layer. After drying, the element is exposed and developed by usual techniques. A sharp image is obtained with no discoloration due to residual dye in background areas. In this example, the dye was bleached by light energy absorbed during the exposure step. When this example is repeated without Compound 12, a blurred and fuzzy image is obtained because of the lack of filter protection.

EXAMPLE 60 Example 66 is repeated except the dye employed is Compound 3 and the silver halide emulsion used and photographic process employed is that used in stabilized print out systems such as described in Example 18 of Ser.

22 No. 625,590 filed Mar. 24, 1967, Bacon et a1. Again, a good reproduction is obtained. The bleaching in this example is caused by both light and heat energy.

HOLOGRAPHIC ELEMENTS The dyes of this invention are useful in the preparation of holographic elements. The development of improved holograms has been carried out on a continuous basis since their introduction in 1948 by Prof. D. Gabor. A typical system for laser holograms is described in Scientific American, February 1968, Vol. 218, No. 2, p. 43. Holograms have in the past been recorded with silver halide emulsions. According to this portion of the invention the dyes described herein can be used in holographic elements to record holograms. Holograms produced in this manner have the advantage of affording higher resolution than the silver halide-based systems since the active particles are of molecular size (i.e., 10-35 A. for dye molecules vs. 500 A. for very fine-grain silver halide particles). Another advantage is that no processing is'required since the dyes are photobleachable (as explained previously) and the image is recorded directly. Therefore, dimensional stability is not a problem. The replacement of silver halide with the dyes of this invention is also economicalyy advantageous.

The holographic elements of this invention are prepared by mixing any of the dyes of this invention with a polymeric binder such as polymethacrylate, gelatin, poly (vinylalcohol), etc. The composition is coated on a support such as glass, Estar, cellulose acetate, Teflon, etc. The thickness of the coating may be varied from a few microns upward.

EXAMPLE 61 A holographic element is prepared by mixing a solution of 0.00793 g. of compound 18 in methanol (14 g.) with 36 grams of 28% poly(2-vinylpyridine) in methanol for about 17 hours. The resulting solution is hand coated at room temperature on 5 x 7 inch glass spectroscopic plates using a knife setting of 0.030 in. The coating is covered and allowed to dry slowly at room temperature.

EXAMPLE 62 A holographic element is prepared in the same manner as Example 68 except compound 11 is used instead of compound 18.

EXAMPLE 63 The elements of Examples 68 and 69 are used in the production of laser holograms. The system employed is similar to that described in the Scientific American article (op. cit.). A laser beam is divided by a beam splitter and directed by a combination of mirrors and lenses such that the reference beam impinges directly on the test coating while the other illuminates a ground glass object. The object used is a 1 cm. square spot of illuminated ground glass placed close to the holographic element so that the reference beam and object beam illuminate an area approximately 1%" square on the coating. The exposure times range from l0-15 seconds with a 900 mw. laser. Each of the coatings produce good recordings of holographic fringes.

The invention has been described in detail with particular reference to certain preferred embodiments thereof, and it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

We claim:

1. A heat-sensitive copying element comprising a support containing a compound having the formula:

wherein:

R is and acyl radical;

R and R are each selected from the group consisting of an aryl radical, a hydrogen atom and an alkyl radical; and

X is an acid anion.

2. The heat-sensitive element of Claim 1 wherein the compound is coated on the support.

3. The heat-sensitive element of Claim 1 wherein the compound is imbibed into the support.

4. The heat-sensitive element of Claim 1 wherein the compound is dispersed in a vehicle which is coated on the support.

5. A heat -sensitive image-forming composition comprising a compound having a formula selected from the group consisting of:

Q Q and Q each represent the non-metallic atoms necessary to complete a 5- to 6-membered heterocyclic ring;

11 is a positive integer from 1 to 4;

m is a positive integer from 1 to 3;

g is a positive integer from 1 to 2;

X is an acid anion;

L is a methine linkage;

R is selected from the group consisting of an alkyl radical and an acyl radical;

R is selected from the group consisting of an aryl radical, a hydrogen atom and an alkyl radical;

R and R are each cyano radicals;

R is selected from the group consisting of an alkyl radical, an alkenyl radical, an aryl radical and an alkoxy radical; and

G is selected from the group consisting of an anilinovinyl radical and an aryl radical.

6. A heat-sensitive image-forming composition according to claim 5 in which said compound is defined by the formula:

Q and Q each represent the non-metallic atoms necessary to complete a 5- to 6-membered heterocyclic ring;

n is a positive integer from 1 to 4;

g is a positive integer from 1 to 2;

X is an acid anion;

L is a methine linkage;

24 R is selected from the group consisting of an alkyl and an acyl radical; R is selected from the group consisting of an aryl radical, a hydrogen atom and an alkyl radical; and R is selected from the group consisting of an alkyl radical, an alkenyl radical, an aryl radical and an alkoxy radical. 7. A heat-sensitive image-forming composition according to claim 5 in which said compound is defined by the formula:

wherein:

Q and Q each represent the non-metallic atoms necessary to complete a 5- to G-membered heterocyclic ring;

m is a positive integer from 1 to 3;

g is a positive integer from 1 to 2;

L is a methine linkage;

R is selected from the group consisting of an alkyl radical and an acyl radical; and

R is selected from the group consisting of an aryl radical, a hydrogen atom and an alkyl radical. 8. A heat-sensitive image-forming composition according to claim 5 in which said compound is defined by the formula:

wherein:

Q represents the non-metallic atoms necessary to complete a 5- to membered heterocyclic ring;

m is a positive integer from 1 to 3;

g is a positive integer from 1 to 2;

L is a methine linkage;

R is selected from the group consisting of an alkyl radical and an acyl radical; and

R is selected from the group consisting of an aryl radical, a hydrogen atom and an alkyl radical.

9. A heat-sensitive image-forming composition according to claim 5 in which said formula-defined compound is selected from the group consisting of:

(a) 3-ethyl-1-methoxy-2-pyridothiacarbocyanine iodide;

(b) 3-ethyl-l-methoXy-4,5'-benzo-2-pyridothiacarbocyanine perchlorate;

(c) 3-ethyl-1-methoxyoxa-Z'-pyridocarbocyanine perchlorate;

(d) 1-methoxy-l,3,3-trimethylindo-Z'-pyridocarbocyanine picrate;

(e) 3-ethyl-l-methoxy-2-pyridothiacyanine iodide;

and

(f) 3'-ethyl-l-methoxy-Z-pyridothiadicarbocyanine perchlorate.

10. A heat-sensitive copying element comprising a support and at least one layer of a heat-sensitive composition comprising a compound having a formula selected from the group consisting of:

Q Q and Q each represent the non-metallic atoms necessary to complete a 5,- to 6-mernbered heterocyclic ring;

n is a positive integer from 1 to 4;

m is a positive integer from 1 to 3;

g is a positive integer from 1 to 2;

X is an acid anion;

L is a methine linkage;

R is selected from the group consisting of an alkyl radical and an acyl radical;

R is selected from the group consisting of an aryl radical,

a hydrogen atom and an alkyl radical;

R is selected from the group consisting of an alkyl radical,

an alkenyl radical, an aryl radical and an alkoxy radical; and

G is selected from the group consisting of an anilinovinyl and an aryl radical.

11. A heat-sensitive copying element comprising a support having thereon at least one layer of a heat-sensitive composition comprising a cyanine dye having a first and a second 5- to 6-membered nitrogen-containing heterocyclic nucleus joined by a methine linkage; the first of said nuclei being selected from the group consisting of a l-alkoxypyridyl nucleus and a l-alkoxyquinolyl nucleus, each of said first nuclei being joined at a carbon atom thereof to said linkage; and said second nucleus being a heterocyclic nucleus of the type contained in cyanine dyes joined at a carbon atom thereof to said linkage, to complete said cyanine dye.

12. A heat-sensitive copying element comprising a support having thereon at least one layer of a heat-sensitive composition comprising at least one compound having the formula:

Q is selected from the group consisting of a pyridyl nucleus and a quinolyl nucleus;

Q represents the non-metallic atoms necessary to complete a 5- to 6-membered heterocyclic ring;

X is an acid anion;

R is an alkyl radical;

R is selected from the group consisting of an aryl radical,

a hydrogen atom and an alkyl radical;

L is a methine linkage;

g is a positive integer from 1 to 2;

n is a positive integer from 1 to 4; and

26 R is selected from the group consisting of an alkyl radical, an alkenyl radical, an aryl radical and an alkoxy radical. v 13. A heat-sensitive copying element comprising a support and at least one layer of a heat-sensitive composition comprising a compound having the formula:

wherein:

R is selected from the group consisting of an alkyl radical and an acyl radical;

L is a methine linkage;

G is selected from the group consisting of an anilinovinyl radical and a phenyl radical;

m is a positive integer from 1 to 3;

X is an acid anion;

Q represents the atoms necessary to complete a 5- to '6- membered heterocyclic ring; and

R is selected from the group consistin of an aryl radical,

a hydrogen atom and an alkyl radical.

14. The heat-sensitive copying element of claim 13 wherein said heat-sensitive composition is imbibed into the support.

15. The heat-sensitive copying element of claim 13 wherein said-heat-sensitive composition is coated on the support.

16. The heat-sensitive copying element of claim 13 wherein said formula-defined compound is dispersed in a vehicle which is coated on the support.

17. A heat-sensitive image-forming element comprising a support having coated thereon a composition comprising gelatin and 3'-ethyl-1-methoxy-4',5'-benzo-2-pyridothiacarbocyanine perchlorate.

References Cited UNITED STATES PATENTS 3,582,342 6/1971 Itano et al 9690 R 3,597,212 8/1971 Webster et al 11736.8 X 3,615,432 10/1971 Jenkins et al 96--27 3,532,499 10/ 1970 Willams et a1 9666.3 3,770,451 11/1973 Jenkins et a1. 96-135 THOMAS J. HERBERT, 1a., Primary Examiner US. Cl. X.R.