Color Diffusion Transfer Process Photographic Elements

1. Field of the Invention

The present invention relates to photographic elements having a neutralizing system for a color diffusion process and particularly to photographic elements comprising a novel timing layer in which the "processing temperature tolerance" is increased. The photographic elements of the present invention are capable of providing definite image densities regardless of variation of temperature because they have an increased "processing temperature tolerance".

2. Description of the Prior Art

Hitherto, it is well known in the color diffusion transfer process to provide a neutralizing layer in order to decrease the pH after transferring diffusible dyes or dye developing agents to a mordanting layer as a result of development using an aqueous alkaline developing solution.

However, if the pH is rapidly decreased by providing a neutralizing layer, the development is interrupted. In order to prevent such a defect, it is also well known to utilize a layer which controls the reduction of the pH with time, namely a "timing layer", together with the neutralizing layer.

A neutralizing system containing these layers can be divided into two types, one type having a timing layer in which the water permeability is inversely proportional to the temperature and the other type having a timing layer in which the water permeability is directly proportional to the temperature.

In using a timing layer in which the water permeability is inversely proportional to the temperature, the period of time at a high pH (preferably, a pH of about 10 or more) for developing silver halide and forming an imagewise distribution of diffusible dyes increases as the temperature increases. A neutralizing system having a timing layer which is temperature dependent is fundamentally suggested in Japanese Patent Publication 15756/69. Further, materials for the timing layer, include polyvinyl amide type polymers described in U.S. Pat. Nos. 3,421,893 and 3,575,701. A neutralizing system having a timing layer wherein the above described materials are used where the period time at high pH increases as the temperature increases is advantageously utilized for the color diffusion transfer process but has the disadvantages that the development rate or the diffusion rate of the dye developing agent is high and excessive amounts of dyes are adsorbed in the mordanting layer at low temperature, such as the color diffusion transfer process described in U.S. Pat. Nos. 2,983,606, 3,415,644 and 3,415,645.

On the other hand, a neutralizing system having a timing layer in which the water permeability is directly proportional to the temperature where the above-described period of time at a high pH decreases as the temperature increases is advantageously utilized for the color diffusion transfer process which uses dye image forming materials which are not diffusible initially but release a diffusible dye as a result of an oxidation-reduction reaction or a coupling reaction thereof with an oxidation product of the developing agent (hereinafter, materials of the former type are called "DRR compounds" and materials of latter type are called "DDR couplers") as described in Japanese Patent Application (OPI) 33826/73 and U.S. Pat. Nos. 3,929,760, 3,931,144 and 3,932,381. Namely, the delay of the development of silver halide and the delay of the above described oxidation-reduction reaction at a low temperature and the deterioration of densities of transferred color images caused by the delay of the diffusion of dyes can be corrected by prolonging the period of time at high pH (namely prolonging the period of time where developing of silver halide and releasing and transferring of the dyes can occur).

Examples of timing layers where the water permeability increases as the temperature increases are timing layers composed of polyvinyl alcohol as described in U.S. Pat. No. 3,362,819, layers described in Japanese Patent Application (OPI) No. 22935/74 (namely, timing layers containing a water impermeable continuous phase composed of a film forming polymer component produced from an aqueous film forming polymer dispersion and a water permeable heterogeneous phase) and layers described in Research Disclosure page 86, (Nov. 1976) (namely, timing layers formed from a latex of methyl acrylate-vinylidene chloride-itaconic acid copolymers or acrylonitrile-vinylidene chloride-acrylic acid copolymers).

However, in the timing layers described in Japanese Patent Application (OPI) No. 22935/74, the delay in development can not be sufficiently compensated for, because the degree of the decrease of the permeability in the low temperature range is small. Further, in the timing layers described in Research Disclosure, supra, there is the defect that the cost of production is high, because it is necessary to use vinylidene chloride which requires special equipment for producing the polymer latex since it is hazardous to humans and gaseous at normal temperature. Further, when the thus-produced latex is used to form a film, it is necessary to use dry air having a high temperature at a step where the film is not sufficiently dried and, consequently, the timing layer causes various defects by rapid vaporizing of water. For example, spots sometimes occur in the resulting photographic images.

Accordingly, an object of the present invention is to eliminate the above-described various defects in prior known techniques and to provide photographic elements for the color diffusion transfer process which have a neutralizing system capable of providing excellent photographic characteristics.

The above-described objects can be attained effectively by using a timing layer formed from a polymer latex (i.e., a film forming aqueous dispersion) which is produced by emulsion polymerization of (1) each of (A) at least one monomer selected from the group consisting of ethylene-type monomers having at least a free carboxylic acid group, a free sulfonic acid group or a free phosphoric acid group or a salt thereof and (B) at least one monomer selected from the group consisting of monomers represented by the following general formula (I) ##STR3## wherein X is a hydrogeon atom, a methyl group or a --COOR.sup.1 group; Y is a hydrogen atom, a methyl group or a --(CH.sub.2).sub.n COOR.sup.2 group; Z is an aryl group, a --COOR.sup.3 group or a ##STR4## group; R.sup.1, R.sup.2 and R.sup.3, which may be the same or different, each represents an aliphatic group or an aryl group; and n is an integer of 0 to 3, or (2) each of (A) at least one monomer selected from the group consisting of the ethylene type monomers described above, (B) at least one monomer selected from the group consisting of monomers represented by the general formula (I) above, and (C) at least one monomer selected from the group consisting of monofunctional or polyfunctional unsaturated monomers other than those monomers described in (A) and (B) above which are copolymerizable with the monomers described in (A) and (B) above and selected from the group consisting of acrylamides, methacrylamides, vinyl ethers, vinyl ketones, allyl compounds, olefins, vinyl heterocyclic compounds, unsaturated nitriles and polyfunctional monomers, as the timing layer in a photographic element for the color diffusion transfer process which has a neutralizing system for decreasing the pH of an aqueous alkaline developing solution where the neutralizing system comprises a neutralizing layer and a timing layer, and wherein the timing layer is positioned on or under the neutralizing layer in direct or indirect contact therewith in such a relation that the developing solution reaches the neutralizing layer through the timing layer.

Monomers of (A), (B) and (C) are illustrated in greater detail below.

The ethylene-type monomers (A), hereinafter Group (A) monomers, may also contain alkoxycarbonyl groups, aryl groups and carbamoyl groups in addition to the above described carboxylic, sulfonic and phosphoric acid groups. Further, the above described acid groups may be linked directly to or may be linked through an atom or an atomic group to the ethylene residue (moiety).

Examples of the monomers of Group (A) include the following monofunctional monomers:

acrylic acid, methacrylic acid, itaconic acid, maleic acid, monoalkyl itaconates (for example, monomethyl itaconate, monoethyl itaconate or monobutyl itaconate, etc.), monoalkyl maleates (for example, monomethyl maleate, monoethyl maleate, monobutyl maleate or monooctyl maleate, etc.). citraconic acid, styrenesulfonic acid, vinylbenzylsulfonic acid, vinylsulfonic acid, acryloyloxyalkyl sulfonic acids (for example, acryloyloxymethyl sulfonic acid, acryloyloxyethyl sulfonic acid, acryloyoxypropyl sulfonic acid and acryloyloxybutyl sulfonic acid, etc.), methacryloxyalkyl sulfonic acids (for example, methacryloyloxymethyl sulfonic acid, methacryloyloxyethyl sulfonic acid, methacryloyloxypropyl sulfonic acid and methacryloyloxybutyl sulfonic acid, etc.), 2-acrylamido-2-alkylalkane sulfonic acids (for example, 2-acrylamido-2-methylethanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid and 2-acrylamido-2-methylbutanesulfonic acid, etc.), 2-methacylamido-2-alkylalkane sulfonic acids (for example, 2-methacrylamido-2-methylethanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid and 2-methacrylamido-2-methylbutanesulfonic acid, etc.), mono(acryloyloxyalkyl) phosphates (for example, mono(acryloyloxyethyl)phosphate and mono(3-acryloyloxypropyl)phosphate, etc.) and mono(methacryloyloxyalkyl)phosphates (for example, mono(methacryloyloxyethyl)phosphate and mono(3-methacryloyloxypropyl)phosphate, etc.), etc.

Further, the alkyl moiety in the above-described monomers of Group (A) is, for example, one having 1 to 8 carbon atoms. These acids representative of monomers of Group (A), s ethylene-type monomers containing a carboxylic acid group, a sulfonic acid group or a phosphoric acid group may also be in the form of the alkali metal salts thereof (preferably, Na.sup.+ or K.sup.+) or the ammonium salts thereof.

Examples of suitable aliphatic groups represented by R.sup.1 to R.sup.3 in the general formula (I) for monomers of the general formula (I), hereinafter Group (B) monomers, include straight, branched or cyclic alkyl groups and substituted alkyl groups. These alkyl groups or the alkyl moieties thereof preferably have 1 to 12 carbon atoms.

Examples of substituents in the substituted alkyl groups include aryl groups, aryloxy groups, halogen atoms, cyano groups, acyl groups, alkylcarbonyloxy groups, arylcarbonyloxy groups amino groups (including amino groups substituted with one or two alkyl groups and aryl groups), hydroxy groups, alkoxy groups, and heterocyclic residues (e.g., a 5- or 6-membered ring, which may be unsaturated or saturated and which may be condensed with an aromatic ring and in which the hetero atom includes oen or more of an oxygen atom, a nitrogen atom and a sulfur atom, etc.), etc.

Examples of suitable aryl groups represented by R.sup.1 to R.sup.3 in the general formula (I) include, of course, both unsubstituted and substituted phenyl and naphthyl groups. Examples of suitable substituents thereof include alkyl groups in addition to the substituents described above the substituted alkyl group for R.sub.1 to R.sub.3.

Examples of the monomers of Group (B) include monofunctional monomers such as acrylic acid esters, methacrylic acid esters, crotonic acid esters, vinyl esters, maleic acid diesters, fumaric acid diesters, itaconic acid diesters and styrenes, etc.

Further specific examples of these Group (B) monomers include monofunctional monomers such as methyl acrylate, ethyl acrylate, n-propylacrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, tert-octyl acrylate, 2-phenoxyethyl acrylate, 2-chloroethyl acrylate, 2-bromoethyl acrylate, 4-chlorobutyl acrylate, cyanoethyl acrylate, 2-acetoxyethyl acrylate, dimethylaminoethyl acrylate, benzyl acrylate, methoxybenzyl acrylate, 2-chlorocyclohexyl acrylate, cyclohexyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, phenyl acrylate, 5-hydroxypentyl acrylate, 2,2-dimethyl-3-hydroxypropyl acrylate, 2-methoxyethyl acrylate, 3-methoxybutyl acrylate, 2-ethoxyethyl acrylate, 2-iso-propoxyethyl acrylate, 2-butoxyethyl acrylate, 2-(2-methoxyethoxy)ethyl acrylate, 2-(2-butoxyethoxy)ethyl acrylate, .omega.-methoxypolyethylene glycol acrylate (mean polymerization degree of polyethylene glycol is about 9), 1-bromo-2-methoxyethyl acrylate, 1,1-dichloro-2-ethoxyethyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzylmethacrylate, chlorobenzyl methacrylate, octyl methacrylate, N-ethyl-N-phenylaminoethyl methacrylate, 2-(3-phenylpropyloxy)ethyl methacrylate, dimethylaminophenoxyethyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate, phenyl methacrylate, cresyl methacrylate, naphthyl methacrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, triethyleneglycol monomethacrylate, dipropyleneglycol monomethacrylate, 2-methoxyethyl methacrylate, 3-methoxybutyl methacrylate, 2-acetoxyethyl methacrylate, acetoacetoxyethyl methacrylate, 2-ethoxyethyl methacrylate, 2-iso-propoxyethyl methacrylate, 2-butoxyethyl methacrylate, 2-(2-methoxyethoxy)ethyl methacrylate, 2-(2-ethoxyethoxy)ethyl methacrylate, 2-(2-butoxyethoxy)ethyl methacrylate, .omega.-methoxypolyethylene glycol methacrylate (mean polymerization degree of polyethylene glycol is about 6), vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyldimethylpropionate, vinyl ethylbutyrate, vinyl valerate, vinyl caproate, vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxyacetate, vinyl butoxyacetate, vinyl phenylacetate, vinyl acetoacetate, vinyl lactate, vinyl-.beta.-phenyl-butyrate, vinyl cyclohexylcarboxylate, vinyl benzoate, vinyl salicylate, vinyl chlorobenzoate, vinyl tetrachlorobenzoate, vinyl naphthoate, styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, butylstyrene, hexylstyrene, cyclohexylstyrene, decylstyrene, benzylstyrene, chloromethylstyrene, trifluoromethylstyrene, ethoxymethylstyrene, acetoxymethylstyrene, methoxystyrene, 4-methoxy-3-methylstyrene, dimethoxystyrene, chlorostyrene, dichlorostyrene, trichlorostyrene, tetrachlorostyrene, pentachlorostyrene, bromostyrene, dibromostyrene, iodostyrene, fluorostyrene, trifluorostyrene, 2-bromo-4-trifuluoromethylstyrene, 4-fluoro-3-trifluoromethylstyrene, vinylbenzoic acid methyl ester, butyl crotonate, hexyl crotonate, glycerin monocrotonate, dimethyl itaconate, diethyl itaconate, dibutyl itaconate, diethyl maleate, dimethyl maleate, dibutyl maleate, diethyl fumarate, dihexyl fumarate and dibutyl fumarate, etc.

Examples of the monomers other than those of Group (A) and Group (B) and copolymerizable therewith, hereinafter Group (C) monomers, include the following compounds:

acrylamides: for example, methylacrylamide, ethyl acrylamide, propylacrylamide, isopropylacrylamide, butylacrylamide, tert-butylacrylamide, heptylacrylamide, tert-octylacrylamide, cyclohexylacrylamide, benzylacrylamide, hydroxymethylacrylamide, methoxyethylacrylamide, dimethylaminoethylacrylamide, hydroxyethylacrylamide, phenylacrylamide, hydroxyphenylacrylamide, tolylacrylamide, naphthylacrylamide, dimethylacrylamide, diethylacrylamide, dibutylacrylamide, di-isobutylacrylamide, N-(1,1-dimethyl-3-oxobutyl)acrylamide, methylbenzylacrylamide, benzyloxyethylacrylamide, .beta.-cyanoethylacrylamide, acryloylmorpholine, N-methyl-N-acryloylpiperazine, N-acryloylpiperidine, N-(1,1-dimethyl-3-hydroxybutyl)acrylamide, N-.beta.-morpholinoethylacrylamide, N-acryloylhexamethyleneimine, N-hydroxyethyl-N-methylacrylamide, N-2-acetoamidoethyl-N-acetylacrylamide and acrylhydrazine, etc.;

methacrylamides: for example, methylmethacrylamide, tert-butylmethacrylamide, tert-octylmethacrylamide, benzylmethacrylamide, cyclohexylmethacrylamide, phenylmethacrylamide, dimethylmethacrylamide, diethylmethacrylamide, dipropylmethacrylamide, hydroxyethyl-N-methylmethacrylamide, N-methylphenylmethacrylamide, N-ethyl-N-phenylmethacrylamide and methacrylhydrazine, etc.;

allyl compounds: for example, allyl acetate, allyl caproate, allyl caprylate, allyl laurate, allyl palmitate, allyl stearate, allyl benzoate, allyl acetoacetate, allyl lactate, allyloxyethanol, allyl butyl ether and allyl phenyl ether, etc.;

vinyl ethers: for example, methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, ethylhexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinyl ether, 1-methyl-2,2-dimethylpropyl vinyl ether, 2-ethylbutyl vinyl ether, hydroxyethyl vinyl ether, diethylene glycol vinyl ether and dimethylaminoethyl vinyl ether, etc.; vinyl ketones: for example, methyl vinyl ketone, phenyl vinyl ketone and methoxyethyl vinyl ketone, etc.;

olefins: for example, unsaturated hydrocarbons such as dicyclopentadiene, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, 5-methyl-1-nonene, 5,5-dimethyl-1-octene, 4-methyl-1-hexene, 4,4-dimethyl-1-pentene, 5-methyl-1-hexene, 4-methyl-1-heptene, 5-methyl-1-heptene, 4,4-dimethyl-1-hexene, 5,5,6-trimethyl-1-heptene, 1-dodecene and 1-octadecene, etc.;

vinyl heterocyclic compounds (where the heterocyclic ring may be a 5- or 6-member ring, which may be condensed with an aromatic ring and in which the hetero atoms include one or more of a nitrogen atom, an oxygen atom and a sulfur atom): for example, N-vinyloxazolidone, vinylpyridine, vinylpicoline, N-vinylimidazole, N-vinyl-2-methylimidazole, N-vinyltriazole, N-vinyl-3,5-dimethyltriazole, N-vinylpyrrolidone, N-vinyl-3,5-dimethylpyrazole, N-vinylcarbazole, vinylthiophene, N-vinylsuccinimide, N-vinylglutarimide, N-vinyladipinimide, N-vinylpyrrolidone, N-vinylpiperidone, N-vinyl-.epsilon.-caprolactam and N-vinyl-2-pyridone, etc.;

unsaturated nitriles: for example, acrylonitrile and methacrylonitrile, etc.;

polyfunctional monomers: for example, polyfunctional monomers having a plurality of vinyl groups (for example, 2 to 3 vinyl groups), for example, aliphatic or aromatic hydrocarbons having a plurality of vinyl groups (such as butadiene and divinylbenzene), bis- or tris-.alpha.,.beta.-unsaturated carbonyl compounds (for example, diallylphthalate, ethyleneglycol dimethacrylate, ethylene glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol trimethacrylate and compounds having the following formulas ##STR5## and polyfunctional monomers having a vinyl group and an active methylene group (for example, acetoacetoxyethyl methacrylate described in Japanese Patent Application (OPI) 5819/70, etc.), etc.

Of these monomers, acrylic acid, methacrylic acid, itaconic acid, 2-acrylamido-2-methylpropanesulfonic acid and phosphoric acid esters having polymerizable unsaturated functional groups as described above (but having a free phosphoric acid group of a salt thereof) are preferred as the monomers of Group (A) from the standpoint of hydrophilic property, hydrophobic property and reactivity of the monomer, or stability and film-forming ability of the polymer latex, etc., and acrylic acid is most preferred. Acrylic acid esters, methacrylic acid esters and styrenes are preferred as monomers of Group (B), and butylacrylate and styrene are most preferred.

The ratio of monomer (A) and monomer (B) or monomer (A), monomer (B) and monomer (C) components in the copolymers of the polymer latex can be appropriately changed depending on the characteristics desired for the photographic element for the color diffusion transfer process which has a timing layer made of the polymer latex. When the ratio of the Group (A) monomer component increases, the water permeability of the timing layer formed using the latex increases. A preferred amount of the group (A) monomer component is in the range of about 0.1.times.10.sup.-3 mol to about 2.2.times.10.sup.-3 mol per gram of the solid content of the latex polymer. A particularly preferred amount of the Group (A) monomer component is in the range of 0.4.times.10.sup.-3 mol to 1.0.times.10.sup.-3 mol per gram of the solid content of the latex polymer. A preferred amount of the Group (B) monomer component is in the range of about 55 to about 99% by weight based on the solid content of the polymer latex and particularly 80 to 99% by weight. A preferred amount of the Group (C) monomer component is in the range of 0 to about 49% by weight and particularly 0 to 19% by weight of the solid content of the polymer latex. A suitable molecular weight for the polymer latex is about 5,000 to about 100,000, preferably 20,000 to 50,000.

The ratio of the above described monomer components is based on the relative ratio of monomers added to a polymerization reactor in the conventional free radical polymerization process.

Typical examples of preferred latex polymers composing the timing layer of the present invention include the following materials, but the present invention is not to be construed as being limited to these examples.

(1) Ethyl methacrylate-acrylic acid copolymer (97:3)

(2) n-Propyl methacrylate-acrylic acid copolymer (96:4)

(3) n-Butyl methacrylate-acrylic acid copolymer (97.5:2.5)

(4) n-Butyl methacrylate-acrylic acid copolymer (96:4)

(5) sec-Butyl methacrylate-acrylic acid copolymer (97:3)

(6) tert-Butyl methacrylate-acrylic acid copolymer (98:2)

(7) Ethyl methacrylate-itaconic acid copolymer (98:2)

(8) n-Butyl methacrylate-itaconic acid copolymer (97.5:2.5)

(9) Cyclohexyl methacrylate-acrylic acid copolymer (97:3)

(10) Tetrahydrofurfuryl methacrylate-acrylic acid copolymer (96:4)

(11) 2-Acetoxyethyl methacrylate-acrylic acid copolymer (97:3)

(12) Ethyl acrylate-methacrylic acid copolymer (90:10)

(13) Benzyl acrylate-acrylic acid copolymer (96:4)

(14) Phenyl acrylate-acrylic acid copolymer (97:3)

(15) n-Propyl methacrylate-maleic acid copolymer (99:1)

(16) n-Butyl methacrylate-sodium vinylbenzylsulfonate copolymer (91:9)

(17) Ethyl acrylate-2-acrylamido-2-methylpropanesulfonic acid copolymer (93:7)

(18) n-Propyl acrylate - sodium 2-methacryloyloxyethylsulfonate copolymer (92:8)

(19) n-Butyl methacrylate - monoethyl itaconate copolymer (93:7)

(20) sec-Butyl methacrylate - 2-methacryloyloxyethylphosphonate copolymer (91:9)

(21) Styrene - n-butyl acrylate - acrylic acid copolymer (53.4:43.6:3)

(22) Styrene - n-butyl acrylate - acrylic acid copolymer (52.8:43.2:4)

(23) Styrene - ethoxyethyl acrylate - acrylic acid copolymer (48:48:4)

(24) Styrene - n-butyl acrylate - itaconic acid copolymer (48:48:4)

(25) Styrene - n-butyl acrylate - methacrylic acid copolymer (46:46:8)

(26) Styrene - ethyl acrylate - 2-acrylamido-2-methylpropanesulfonic acid copolymer (40:50:10)

(27) Methyl methacrylate - n-butyl methacrylate - itaconic acid copolymer (10:85:5)

(28) Cyclohexyl methacrylate - n-octyl acrylate - acrylic acid copolymer (70:24:6)

(29) Benzyl methacrylate - 2-ethylhexyl acrylate - acrylic acid copolymer (60:35:5)

(30) Phenyl methacrylate - n-butyl acrylate - sodium 2-methacryloyloxyethyl sulfonate copolymer (55:40:5)

(31) Ethyl methacrylate - 2-acetoxyethyl methacrylate - acrylic acid copolymer (30:64:6)

(32) n-Butyl methacrylate - 2-hydroxyethyl methacrylate - acrylic acid copolymer (90:5:5)

(33) n-Butyl methacrylate - acrylic acid - 2-acrylamido-2-methylpropanesulfonic acid copolymer (92:4:4)

(34) Benzyl methacrylate - vinyl acetate - sodium 2-methacryloyloxypropanesulfonate copolymer (30:63:7)

(35) Ethyl methacrylate - vinyl butyrate - acrylic acid copolymer (60:36:4)

(36) Vinyltoluene - ethoxyethyl acrylate - acrylic acid copolymer (53:43:4)

(37) Styrene - di-n-butyl maleate - maleic acid copolymer (50:47:3)

(38) n-Butyl methacrylate - dimethylacrylamide - acrylic acid copolymer (70:25:5)

(39) Cyclohexyl methacrylate - N-(1,1-dimethyl-3-oxobutyl)acrylamide - acrylic acid copolymer (60:36:4)

(40) n-Butyl methacrylate - tert-butyl acrylamide - acrylic acid copolymer (70:26:4)

(41) n-Butyl methacrylate - acrylonitrle - methacrylic acid copolymer (80:12:8)

(42) n-Butyl methacrylate - ethylene glycol dimethacrylate - acrylic acid copolymer (92:3:5)

(43) Styrene - n-butyl acrylate - divinylbenzene - acrylic acid copolymer (50:42:3:5)

(44) Tetrahydrofurfuryl methacrylate - ethyl acrylate - ethylene glycol dimethacrylate - itaconic acid copolymer (60:32:4:4)

(45) n-Hexyl methacrylate - tert-butyl acrylamide - methylenebisacrylamide - 2-acrylamide-2-methylpropanesulfonic acid copolymer (62:26:3:9)

All ratios in the above examples are by weight.

The polymer latex used in the present invention can be synthesized using processes well known to those skilled in the art of synthesizing polymers. The polymer latex can be easily synthesized with reference to the descriptions appearing hereinafter in the present specification and in, e.g., U.S. Pat. Nos. 2,914,499, 3,033,833 and 3,547,899 and Canadian Pat. No. 704,778, etc. Typical examples of synthesis are described below. Unless otherwise indicated all parts, percents, ratios and the like are by weight.

A 1 liter 3-neck flask equipped with a thermometer, a nitrogen inlet conduit, a stirrer, a reflux condenser and a dropping funnel was placed on a steam bath. 5 g of sodium nonylphenoxy polyethylene propanesulfonate ether was put in this flask and 300 ml of distilled water was then added thereto to dissolve. 70 g of n-butyl methacrylate was added to the mixture to emulsify the mixture. 1.868 g of potassium persulfate and 0.75 g of sodium hydrogen sulfite were dissolved in 100 ml of distilled water. 1/3 of the resulting solution (Solution A) was put in the flask. The air in the flask was purged with nitrogen gas. The temperature in the flask was increased to 60.degree. C. and stirring was continued. A polymerization reaction began with the generation of heat. After the generation of heat reached a maximum, 1/4 of the remainder of Solution A was added to the reaction mixture. A mixture of 27.5 g of n-butyl methacrylate and 2.5 g of acrylic acid was added dropwise at once using a dropping funnel and the addition thereof was completed after 30 minutes. The temperature in the flask was kept at 60.degree. C. during the addition. After the conclusion of the addition, 1/2 of the remainder of Solution A was added to the mixture after the lapse of 1 hour. After 30 minutes, the remainder of Solution A was added to the mixture. After stirring for 1 hour at 60.degree. C., the temperature was decreased to room temperature (about 20.degree.-30.degree. C.) to finish the reaction.

5 g of sodium nonylphenoxy polyoxyethylene propanesulfonate ether was placed into the same type of apparatus as described in Synthesis Example 1, and dissolved using 300 ml of distilled water. After purging the air in the flask with nitrogen gas, a mixture of 96 g of n-butyl methacrylate and 4 g of acrylic acid was added thereto and an emulsion was formed. 1.975 g of potassium persulfate and 0.761 g of sodium hydrogen sulfite were dissolved in 100 ml of distilled water (Solution A.sub.2). 1/2 of Solution A.sub.2 was put in the flask. When the temperature in the flask had risen to 60.degree. C., a polymerization reaction began with the generation of heat. Stirring was continued while the temperature in the flask was kept at 60.degree. C. by reducing the temperature of the steam bath. After 2 hours, 1/2 of the remainder of Solution A.sub.2 was added to the mixture. After 30 minutes, the remainder of Solution A.sub.2 was added thereto. After the stirring had been continued at 60.degree. C. for 1 hour, the temperature was decreased to room temperature to finish the reaction.

A 2 liter 3-neck flask equipped with a thermometer, a nitrogen inlet tube, a stirrer, a reflux condenser and a dropping funnel was placed on a steam bath. 10 g of sodium nonylphenoxy polyoxyethylene propanesulfonate ether was put in this flask and 600 ml of distilled water was added thereto to dissolve. The air in the flask was purged with nitrogen gas, a mixture of 87.3 g of n-butyl acrylate, 6 g of acrylic acid and 106.7 g of styrene was added thereto and an emulsion was formed. 4.836 g of potassium persulfate and 1.862 g of sodium hydrogen sulfite were dissolved in 200 ml of distilled water (Solution A.sub.3). 1/2 of Solution A.sub.3 was put in the flask. When the temperature in the flask had increased to 60.degree. C., a polymerization reaction began with a generation of heat. Stirring was continued while the temperature in the flask was kept at 60.degree. C. by reducing the temperature of the steam bath. After 2 hours, 1/2 of the remainder of Solution A.sub.3 was added to the mixture. After 30 minutes, the remainder of Solution A.sub.3 was added thereto. After the stirring had been continued at 60.degree. C. for 1 hour, the temperature was reduced to room temperature to finish the reaction.

The synthesis was carried out in the same manner as in Synthesis Example 3 except that the amounts of styrene, n-butyl acrylate and acrylic acid were each 105.6 g, 86.4 g and 8 g, respectively and a solution prepared by dissolving 4.864 g of potassium persulfate and 1.874 g of sodium hydrogen sulfite in 200 ml of distilled water (Solution A.sub.4) was used instead of Solution A.sub.3.

5 g of sodium nonylphenoxy polyoxyethylene propanesulfonate ether was placed in the same type of apparatus as described in Synthesis Example 1, and dissolved by adding 300 ml of distilled water. After purging the air in the flask with nitrogen gas, 48 g of n-butyl acrylate, 48 g of styrene and 4 g of itaconic acid were added to the flask and the mixture was emulsified. 2.342 g of potassium persulfate and 0.902 g of sodium hydrogen sulfite were dissolved in 100 ml of distilled water (Solution A.sub.5). 1/2 of Solution A.sub.5 was put in the flask. When the temperature in the flask was increased to 60.degree. C., a polymerization reaction began with the generation of heat. The stirring was continued while the temperature in the flask was kept to 60.degree. C. by reducing the temperature of the steam bath. After 2 hours, 1/2 of the remainder of Solution A.sub.5 was added to the mixture. After 30 minutes, the remainder of Solution A.sub. 5 was added thereto. After the stirring had been continued at 60.degree. C. for 1 hour, the temperature was reduced to room temperature to finish the reaction.

This synthesis was carried out in the same manner as in Synthesis Example 5 except that the same amounts of 2-ethoxyethyl acrylate and acrylic acid were used instead of butyl acrylate and itaconic acid and a solution prepared by dissolving 2.296 g of potassium persulfate and 0.884 g of sodium hydrogen sulfite in 100 ml of distilled water (Solution A.sub.6) was used instead of Solution A.sub.5.

This synthesis was carried out in the same manner as in Synthesis Example 5 except that 40 g of styrene, 50 g of ethyl acrylate and 10 g of 2-acrylamido-2-methylpropane-sulfonic acid were used instead of styrene, butyl acrylate and itaconic acid in Synthesis Example 5 and a solution prepared by dissolving 2.232 g of 2,2'-azobis-(2-amidinopropane) hydrochloride in 100 ml of distilled water (Solution A.sub.7) was used instead of Solution A.sub.5.

Latexes containing other polymers can be synthesized in the same manner as described above.

The average particle size of latexes for the timing layer of the present invention are preferably about 0.05 to about 0.4.mu. and particularly 0.1 to 0.2.mu.. However, the average particle size can be suitably adjusted according to the purpose of the timing layer and there is no limitation on the average particle size. (The average particle size is the number mean of the diameter of the particles measured microscopically in the conventional manner).

The timing layer can be produced by applying at least one of the polymer latexes produced by the above described processes just as it is or after dilution with water to the neutralizing layer directly or indirectly. As used herein, the term "indirectly" means that the timing layer of the present invention is applied to the neutralizing layer through another timing layer (for example, a cellulose acetate film) or an adhesion improving layer, etc.

Examples of adhesion improving layers, include layers containing a hydrophilic colloid such as gelatin or polyvinyl alcohol, etc. These layers may function as the timing layer.

The photographic element of the present invention may be a cover sheet for covering the "photosensitive element" (but the neutralizing system is incorporated therein) or may be a so-called laminated film unit which comprises a support, a photosensitive member comprising an "image receiving element" and a "photosensitive element," a "cover sheet" having a neutralizing system and a "processing element" which is provided so that it can be spread between the photosensitive element and the cover sheet, which are applied to the support in turn to form the film unit (but these elements may be strippable, if desired).

Further, the photographic element of the present invention may be a so-called strippable film unit which can be utilized as a negative, wherein a developing solution is spread between an image receiving element applied to a support and an element comprising a neutralizing layer, a timing layer and a photosensitive element applied to a support in this order.

Further, the neutralizing system of the present invention may be present in the image receiving element, although such an embodiment is less preferred than the other embodiments.

The timing layer of the present invention is essentially different from the timing layer described in the above described Japanese Patent Application (OPI) 22935/74 in the following characteristics.

In the latex used in the present invention, surface active agents used for emulsifying monomers during the synthesis of the latex are present (examples of which are described hereinafter). Since water soluble materials are used as such surface active agents, a possible misunderstanding in that the surface active agents function as a water permeable discontinuous phase coexistent with a water impermeable continuous phase as described in Japanese Patent Application (OPI) 22935/74 may arise. Accordingly, it is to be emphasized in the present invention that the surface active agents for emulsification can not be the water permeable discontinuous phase. The reason for this is described below. When the relationship between the function (water permeability) as the timing layer and the amount of the surface active agent used for preparation of the latex of the present invention is plotted graphically, while the amount of the surface active agent used is reduced, it has been found that the water permeability does not depend upon the amount of the surface active agent used, because the amount of the surface active agent added in preparation of the latex is essentially very small (about 0.5 to at most 6% by weight based on the solid content of the latex polymer). Accordingly, this demonstrates that, although the timing layer of the present invention contains a water soluble emulsifying agent in the starting materials used, such an emulsifying agent does not increase the water permeability of the timing layer. Further, in Japanese Patent Application (OPI) No. 22935/74, since the surface active agent is not exemplified as the water permeable discontinuous phase, it is supported that the surface active agent added at preparation of the latex is not the above described discontinuous phase.

The latex for the timing layer of the present invention can be provided by known methods, for example, using a spiral rod coater, an extrusion coater, a dip coater or an air knife coater, etc.

Various kinds of additives may be added to this latex, according to the purpose thereof.

As such additives, it is preferred to use surface active agents for improving wetting at coating, solvents facilitating film formation (for example, methyl Cellosolve or ethyl Cellosolve, etc.), matting agents which are used for preventing adhesion at preparation or at use, such as silica powder or polymer beads, etc., bulking agents for improving the strength of the film (for example, colloidal silica, titanium dioxide, carbon black or diatomaceous earth, etc.) and plasticizers for improving the flexiblity of the film (for example, phthalic acid esters such as dibutyl phthalate or dihexyl phthalate, etc. and phosphoric acid esters such a trialkyl phosphates (e.g., trioctylphosphate) or tricresyl phosphate, etc.), etc. according to the purpose. A preferred amount of the above desribed surface active agents for improving wetting ranges from about 0.05 to 0.5% (by weight). Although the amounts of these other additives can be suitably decided according to the purpose, a preferred amount of each of the additives ranges from about 0.1 to about 20% (by weight) and particularly 1 to 10% (by weight) based on the solid content of the latex polymer.

Although the thickness of the timing layer of the present invention advantageously ranges from about 0.5 to about 20.mu. and particularly 2 to 8.mu., there is no limitation on the thickness. It can be suitably decided according to the purpose of using the timing layer.

In order to dry the timing layer of the present invention on coating, a method of using electromagnetic waves such as infrared rays or ultrashort (VHF) waves, etc., a contact heat-transmission method using a heating drum, or a method of using hot air can be suitably utilized. In any case, it is preferred for a transparent film to be produced from the latex by applying energy which is slightly in excess of the minimum energy necessary to form a transparent film and then the residual volatile components such as water or other materials are evaporated by applying sufficiently high energy. If an excess amount of energy is employed before sufficient film formation has occurred, the volatile components such as water sometimes rapidly evaporate and boiling occurs. In such a case, the resulting timing layer has many defects, such as pores, etc. In these defective areas, the permeation rate of the alkaline solution becomes markedly higher than that in the other areas and, consequently, spots are formed sometimes on the photographic images. Since the latex for the timing layer of the present invention forms a transparent film at a comparatively low temperature, a quite uniform defect-free film can be produced, if the drying is carried out in the above described manner as recommended herein.

The timing layer of the present invention not only can control the rate of alkali absorption by the neutralizing layer but also can control migration by diffusion of materials in the layers which are positioned on the opposite side of silver halide emulsion layers on the basis of the timing layer.

An example of a layer which is positioned on the opposite side is the neutralizing layer. The neutralizing layer is illustrated below. It is preferred to previously add to the neutralizing layer development inhibiting agents or precursors thereof (development inhibitor releasing type couplers and hydroquinones, and compounds which release a development inhibitor by hydrolysis as described in French Pat. No. 2,282,124) or reducing agents for preventing fading by light, which cause disadvantageous chemical reactions if they move into the silver halide layers in the initial stage of the development. However, by application of the timing layer of the present invention, it becomes possible to block the migration of these materials so they they do not reach the silver halide emulsion layers in the initial stage of the development and they function after sufficient development has progressed. Of course, it is possible to control the effect of these additives by temperature. For example, when a development inhibiting agent or a precursor thereof for inhibiting excessive development is added to the neutralizing layer, the development is not inhibited at the beginning of the development at any temperature but it is inhibited after sufficient development has progressed to finally stop the development. Accordingly, it becomes possible to prevent the occurrence of strains or prevent an increase of the image densities caused by excessive development. Particularly, when the development temperature is high, stains easily occur due to excessive development, since the development rate is high. In such a case, if the timing layer of the present invention which has the characteristic that the permeability markedly increases as the temperature increases is used, the above described disadvantages are suitably prevented.

Development inhibitor releasing type couplers (DIR coupler), which can be used herein, include those described in, for example, U.S. Pat. Nos. 3,227,554, 3,617,291; 3,701,783, 3,790,384 and 3,632,345, German Patent Applications (OLS) Nos. 2,414,006, 2,454,301 and 2,454,329, British Pat. No. 953,454 and Japanese Patent Application (OPI) No. 69624/77.

Other compounds which release a development inhibitor during development which can be used, are those described in, for example, U.S. Pat. Nos. 3,297,445 and 3,379,529 and German Patent Application (OLS) No. 2,417,914.

When the timing layer of the present invention is used, the effect of maintaining a high pH for a long period at a lower temperature is particularly excellent. Further, since a reduction in the transfer image densities is nearly completely corrected for by adjusting suitably the time for maintaining such a high pH, it is possible to obtain fixed transfer image densities in spite of a variation in the processing temperature.

Further, when the timing layer of the present invention is used, since the water permeability is markedly increased as the temperature increases, it is possible to obtain an effect where the permeation rate of water increases 2.5 times or more with every 10.degree. C. increase in the temperature where the temperature is the range of about 0.degree. C. to about 40.degree. C. By this effect, since the processing solution easily reaches the neutralizing layer by passing through the timing layer of the present invention at high temperature, there is the advantage that the pH of the processing solution is rapidly decreased to inhibit excessive development, namely, the formation of excess transfer images can be prevented.

Furthermore, there is the advantage that the cost of production is very low, because the latex used in the present invention can be produced from inexpensive starting materials using simple equipment. Further, if the latex of the present invention is used, drying after application is gradually carried out at a comparatively low temperature when water is present in the film in a large amount to form a film having less defects and the drying is then carried out at a high temperature by which latex particles sufficiently fuse to complete the film of the timing layer. Accordingly, there is the advantage that causing defects in the photographic images can be minimized.

The effect of the timing layer of the present invention which has a characteristic that water permeability remarkably increases as the temperature increases can be carried out by the correspondence between the variation of photographic development by temperature and variation of water permeability by temperature.

The water permeability of the timing layer is preferably described as the time required for the pH of the alkaline processing solution to decrease on passing through the timing layer and being absorbed in the neutralizing layer.

In this case, when the time required for the pH to reach 10 (it is understood in the photographic art that photographic development is substantially stopped at this pH) is measured, it has been found that there is a very good correspondence between the change in temperature and the change in transfer image densities by temperature. Although the time required for a pH of 10 to be reached can be electrically measured using a glass electrode for measuring pH which was improved for such a purpose, it is preferred to measure the time using a pH indicating dye which does not decompose under alkaline conditions. It is particularly preferred to measure using Thymolphthalein which is a dye whose color changes at a pH of 10 as the pH indicator as described in the following examples.

When the variation of the time by temperature at which the pH of the alkaline processing solution decreases to a pH of 10 is measured for the timing layer of the present invention and prior art timing layers using Thymolphthalein using the method shown in Examples hereinafter of the present invention, it has been found that the variation of time by temperature has a clear interrelation to the variation of image transfer densities by temperature. It is preferred for the measurement temperature to be 25.degree. C. which is a normal temperature and 15.degree. C. and a preferred embodiment of the timing layer of the present invention is prescribed on the basis of the ratio of the time required for reaching a pH of 10 at 15.degree. C. to that at 25.degree. C., namely, T.sub.15 /T.sub.25 (T.sub.15 and T.sub.25 are each the time required for reaching a pH of 10 15.degree. C. or at 25.degree. C.).

It is preferred for the value of T.sub.15 /T.sub.25 measured according to the method described in Example 1 given hereinafter to be in the range of about 250 to about 600% and, particularly, 300 to 500%.

In the timing layer described in Japanese patent application No. 22935/74 discussed above, this range can not be obtained and, consequently, the temperature dependence of the transfer image densities is large when such a timing layer is used.

The silver halide emulsions which can be used in the present invention are hydrophilic colloid dispersions of silver chloride, silver bromide, silver bromochloride, silver bromoiodide, silver iodobromochloride or a mixture thereof. Although the composition of halides is suitably selected according to the purpose or processing conditions of the light-sensitive materials, a silver iodobromide or silver iodobromochloride having an iodine content of about 1% by mol to about 10% by mol (a chloride content of about 30% by mol or less) and the balance of bromide is particularly preferred. Although the grains of the silver halide used may have a conventional grain size or a micrograin size, it is preferred for the average grain size thereof to range from about 0.1 micron to about 2 microns. It is further preferred for the grain size of each grain to be uniform. The grain used may have a cubic crystal form, an octahedral crystal form or a mixed crystal form thereof. These silver halide emulsions can be produced using conventional techniques as described in, for example, P. Glafkides Chimie Photographique Chapters 18-23, 2nd Edition, Paul Montel, Paris (1957).

It is preferred for the silver halide emulsions used in the present invention to be chemically sensitized by heat treatment using the natural sensitizing agents present in gelatin, sulfur sensitizing agents such as sodium thiosulfate or N,N,N'-triethyl thiourea, gold sensitizing agents such as the thiocyanate complex salt or the thiosulfate complex salt of monovalent gold, or reduction sensitizing agents such as stannous chloride or hexamethylenetetramine. In the present invention, although emulsions wherein grains easily form latent images on the surface thereof may be used, it is preferred to use internal latent image type direct reversal emulsions as described in U.S. Pat. Nos. 2,497,875, 2,588,982, 2,456,953, 3,761,276, 3,206,313, 3,317,322, 3,761,266, 3,850,637, 3,923,513, 3,736,140, 3,761,267 and 3,854,949.

The silver halide emulsions used in the present invention may be stabilized using conventional stabilizers. Further, the silver halide emulsions used may contain sensitizing compounds such as polyethylene oxide compounds.

The silver halide emulsions used in the present invention may be spectrally sensitized, if desired. Useful spectral sensitizing agents include dyes such as cyanines, merocyanines, holopolar cyanines, styryls, hemicyanines, oxanols and hemioxonols, etc. Examples of spectral sensitizing agents are described in P. Glafkides supra, Chapters 35-41 and F. M. Hamer Cyanine Dyes and Related Compounds, Interscience (1964). Particularly, cyanines wherein a nitrogen atom in the basic heterocyclic nuclei is substituted with an aliphatic group (for example, an alkyl group) having a hydroxyl group, a carboxyl group or a sulfo group, such as those described in U.S. Pat. Nos. 2,503,776, 3,459,553 and 3,177,210 are advantageoulsy used for practicing the present invention.

Suitable color image forming materials for the diffusion transfer process used in combination with the photographic emulsions of the present invention are the compounds described in, for example, U.S. Pat. Nos. 3,227,551, 3,227,554, 3,443,939, 3,443,940, 3,658,524, 3,698,897, 3,725,062, 3,728,113, 3,751,406, 3,929,760, 3,931,144 and 3,932,381, British Pat. Nos. 840,731, 904,364 and 1,038,331, German Patent Applications (OLS) Nos. 1,930,215, 2,214,381, 2,228,361, 2,242,762, 2,317,134, 2,402,900, 2,406,626 and 2,406,653 and Japanese Patent Applications (OPI) Nos. 114,424/74, 126332/74, 33826/73, 126331/74, 115528/75, 113624/76 and 104343/76, etc. Particularly, DRR compounds are preferred for use.

Examples of DRR compounds include 1-hydroxy-2-tetramethylenesulfamoyl-4-[3'-methyl-4'-(2"-hydroxy-4"-methyl- 5"-hexadecyloxyphenylsulfamoyl)phenylazo]naphthalene as a magenta image forming material, and 1-phenyl-3-cyano-4-(3'-[2"-hydroxy-4"-methyl-5"-(2'",4'"-di-t-pentylphenox yacetamido)phenylsulfamoyl]-phenylazo}-5-pyrazolone as a yellow image forming material in addition to the compounds described in the above mentioned patents.

In the present invention, in using DRR compounds, any silver halide developing agent can be used if such is capable of oxidizing DRR compounds. Such a developing agent may be incorporated in the alkaline processing compositions (processing element) or may be incorporated in a suitable layer in the photosensitive element. Examples of developing agents which can be used in the present invention include the following compounds: hydroquinone, aminophenols such as N-methylaminophenol, 1-phenyl-3-pyrazolidone, 1-phenyl-4,4-dimethyl-3-pyrazolidone, 1-phenyl-4-methyl-4-oxymethyl-3-pyrazolidone, N,N-diethyl-p-phenylenediamine, 3-methyl-N,N-diethyl-p-phenylenediamine and 3-methoxy-N-ethoxy-p-phenylenediamine, etc.

Of these compounds, black-and-white developing agents having the ability to reduce stain formation of the image-receiving layer (mordanting layer) are particularly preferred.

In carrying out the present invention, in using DRR compounds, positive images are formed as the transfer images and negative images are formed as the residual images, if the so-called common emulsions wherein the development is carried out according to exposure are used. On the other hand, positive images are obtained on the image receiving element of the film unit, if the so-called direct reversal silver halide emulsions wherein the development is carried out in the non-exposed areas (for example, internal latent image type emulsions or solarization type emulsions, etc.) are used.

Solarization type emulsions, as described in C.E.K. Mees, The Theory of the Photographic Process pages 261-207, McMillan Co., New York, (1942) are useful. Processes for producing these types of emulsions are described, for example, in British Pat. Nos. 443,245 and 462,730 and U.S. Pat. Nos 2,005,837, 2,541,472, 3,367,778, 3,501,305, 3,501,306 and 3,501,307.

The internal latent image type direct positive emulsions advantageously used in the present invention are described in U.S. Pat. Nos. 2,497,875, 2,588,982, 2,456,953 and 3,761,276.

The direct reversal photographic emulsions used in the present invention can be used to form positive images directly by conducting the development in the presence of a fogging agent after imagewise exposing to light or by fogging by applying a uniform exposure (a high illuminance exposure for a short ime, namely, exposure for 10.sup.-2 seconds or less, or a low illuminance exposure for a long time) in surface development processing after imagewise exposing to light, as described in U.S. Pat. No. 2,456,953. It is preferred to use a fogging agent because the degree of fogging can be easily controlled. Although the fogging agent may be added to the developing solution, it is more preferred to incorporate the fogging agent in the light sensitive material. Suitable fogging agents which can be used in emulsions, include hydrazines described in U.S. Pat. Nos. 2,588,982 and 2,568,785, hydrazides and hydrazones described in U.S. Pat. No 3,227,552, and quaternary salt compounds described in British Pat. No. 1,283,835, Japanese Patent Publication No. 38164/74 and U.S. Pat. Nos. 3,734,738, 3,719,494 and 3,615,615.

The amount of the fogging agent used here can be widely changed depending on the results required. Where the fogging agent is added to the light-sensitive materials, the fogging agent is generally used in a range of about 50 mg to about 10 g/mol of Ag and preferably 300 mg to 5 g/mol of Ag.

Where the fogging agent is added to the developing solution, the fogging agent is generally used in a range of about 0.05 to 5 g, preferably 0.1 to 1 g, per liter of the developing solution. Where the fogging agent is in incorporated in a layer in the light-sensitive material, it is effective for the fogging agent to be rendered non-diffusible. A ballast group commonly used for couplers can be linked to the fogging agent to render it non-diffusible.

Further, diffusion transfer positive images can be also obtained using a DIR reversal emulsion process as described in U.S. Pat. Nos. 3,227,551, 3,227,554 and 3,364,022 or a reversal emulsion process by solution physical development as described in British Pat. No. 904,364. Processes for forming color diffusion transfer images are described in U.S. Pat. Nos. 3,227,550 and 3,227,552 and British Pat. No. 1,330,524, etc.

Suitable and typical color developing agents which can be used with DDR couplers in the present invention are p-phenylenediamine derivatives described in U.S. Pat. Nos. 3,227,552, 2,559,643 and 3,813,244. Further, p-aminophenol derivatives as described in Japanese Patent Application (OPI) No. 26134/73 can be advantageously used. Such color developing agents are preferably added to an alkaline processing composition for development retained in a rupturable container. The color developing agents may be added to a layer provided on a photosensitive element of the film unit or may be added to the same silver halide emulsion layer.

The image receiving element should have a mordanting layer composed of a mordanting agent such as poly-4-vinylpyridine-latex (particularly, in polyvinyl alcohol) as described in U.S. Pat. No. 3,148,061, polyvinylpyrrolidone as described in U.S. Pat. No. 3,003,872 and polymers containing quaternary ammonium salt groups or phosphonium salt groups as described in U.S. Pat. Nos. 3,239,337, 3,958,995, 3,770,439 and 3,898,088 and German Patent Application (OLS) No. 2,264,073, etc. The basic polymers described in U.S. Pat. Nos. 2,882,156, 3,625,694 and 3,709,690 are also effective as mordanting agents. In addition, mordanting agents described in U.S. Pat. Nos. 2,484,430, 3,271,147, 3,184,309 and 3,271,147, etc. are also effective.

The photosensitive element used in the present invention has a support which does not undergo any marked dimensional change during processing. Examples of such supports include cellulose acetate films, polystryene films, polyethylene terephthalate films and polycarbonate films, etc. In addition, examples of effective supports include paper and laminated paper, whose surface is covered with a water impermeable polymer such as polyethylene.

Typical examples of preferred acid materials such as polymeric acids, etc., composing the neutralizing layer used in the present invention include materials described in U.S. Pat. Nos. 2,983,606, 2,584,030 and 3,362,819. The neutralizing layer may contain polymers such as cellulose nitrate or polyvinyl acetate and a plasticizer as described in U.S. Pat. No. 3,557,237 in addition to the acid materials. The acid materials may be incorporated into the film unit in the form of microcapsules as described in German Patent Application (OLS) No. 2,038,254.

The processing composition used in the present invention is a liquid composition containing processing components necessary for the development of the silver halide emulsions and for formation of the diffusion transfer dye images, wherein the solvent is mainly water and may contain hydrophilic solvents such as methanol or methyl Cellosolove. The processing composition contains an alkali in an amount sufficient to maintain the pH required for the development of the emulsion layers and to neutralize acids (for example, hydrohalic acids such as hydrobromic acid or carboxylic acids such as acetic acid, etc.) formed during the steps of development and dye image formation. Examples of alkalis which can be used include lithium hydroxide, sodium hydroxide, potassium hydroxide, a dispersion of calcium hydroxide, alkali metal salts of weak acids or alkaline earth metals salts of weak acids and amines such as tetramethylammonium hydroxide, sodium carbonate, trisodium phosphate or diethylamine, etc. It is preferred to add an alkali in such a concentration that the pH becomes about 12 or more and preferably 14 or more at room temperature. A further preferred processing composition contains hydrophilic polymers having a high molecular weight such as polyvinyl alcohol, hydroxyethyl cellulose or sodium carboxymethyl cellulose. These polymers not only provide the processing composition with a viscosity of more than about 1 poise and preferably a viscosity in the range of several hundred (500-600) to 1000 poises at room temperature which facilitates a uniform spreading of the composition at processing but also form a nonfluid film to help unify the film unit after processing when the composition was concentrated by diffusion of the aqueous solvent into the photosensitive element and the image receiving element during processing. After the formation of the diffusion transfer dye image is substantially completed, this polymer film inhibits movement of coloring components into the image receiving layer to prevent a deterioration of the images.

It is sometimes advantageous for the processing composition to contain light absorbing materials such as TiO.sub.2, carbon black or a pH indicator or desensitizing agents described in U.S. Pat. No. 3,579,333 in order to prevent fogging of the silver halide emulsion by ambient light during processing, e.g., outside a camera. Further, development inhibiting agents such as benzotriazole may be added to the processing composition, if desired.

It is preferred for the above described processing composition to be used in a rupturable container, e.g., as described in U.S. Pat. Nos. 2,543,181, 2,643,886, 2,653,732, 2,723,051, 3,056,491, 3,056,492 and 3,152,515, etc.

The photographic film unit of the present invention, namely, a film unit capable of being processed by passage through a pair of opposing pressure applying members, comprises the following elements:

(1) a photosensitive element as described above,

(2) an image receiving element as described above, and

(3) means for releasing the alkaline processing composition in the interior of the film unit, such as a rupturable container, and containing a silver halide developing agent.

The photosensitive element in the above described film unit is superposed on the image receiving element in a face-to-face relationship after exposure to light, and is processed by spreading the alkaline processing composition between these two elements. In this case, the image receiving element may be stripped off (delaminated) after completion of the diffusion transfer process. Further, the film unit may be of the type where the images can be observed without stripping off the image receiving element, e.g., as described in U.S. Pat. No. 3,415,645.

In another embodiment, the image receiving layer in the above described film unit may be arranged in a photosensitive element comprising a support and a photosensitive silver halide emulsion layer. For example, as described in Belgian Pat. No. 757,960, an image receiving layer, a substantially opaque light-reflection layer (for example, a TiO.sub.2 layer) and a photosensitive layer composed of one or more light-sensitive elements are applied to a transparent support, can be effectively used. After the light-sensitive element is exposed to light, the light-sensitive element is superposed on an opaque cover sheet (which includes the neutralizing system of the present invention) in a face-to-face relationship and the processing composition is spread therebetween.

Another embodiment which is an integral type embodiment capable of being utilizing in the present invention is described in Belgian Pat. No. 757,959. According to this embodiment, an image receiving layer, a substantially opaque light reflection layer (for example, as described above) and one or more photosensitive layers are applied to a transparent support and a transparent cover sheet (which includes the neutralizing system of the present invention) is superposed thereon in a face-to-face relation. A rupturable container retaining an alkaline processing composition containing a light absorbent (for example, carbon black) is positioned so that it is adjacent the top layer of the above described light-sensitive layer or transparent top sheet. This film unit is exposed to light through the transparent cover sheet and taken out of the camera, by which the container is ruptured by the pressing members, the processing composition (containing the light-shielding agent) is spread uniformly between the light-sensitive layer and the cover sheet. Thus the film unit is shielded from light and the development proceeds.

Other useful film units of non-peel apart type embodiments capable of using DRR compounds or DDR couplers in the present invention are described in U.S. Pat. Nos. 3,415,644, 3,415,645, 3,415,646, 3,647,487 and 3,635,707 and German patent application (OLS) No. 2,426,980.

The following examples are given to illustrate the present invention in greater detail.

To a polyethylene terephthalate film having a thickness of 100 .mu., a neutralizing layer and a timing layer were applied in turn in the following manners (I) and (II) to produce Photographic Elements No. 1-8 for evaluation as shown in Table 1 below.

A solution (polyacrylic acid solid content: 12%) which was prepared by diluting a 20% solution of polyacrylic acid (Dulymer-AC - 10H, produced by Nippon Junyaku Kogyo Co.; viscosity of 20% by weight aqueous solution (at 25.degree. C.): 20,000-40,000) with water, adding a cross linking agent of the formula ##STR6## in an amount of 0.15 g per g of polyacrylic acid and neutralizing 5% on an equivalent basis of the carboxyl groups in the polyacrylic acid with sodium hydroxide was applied in an amount of 18 g of solid content per square meter by using an extrusion coater and dried with hot air at a velocity of 5 m per second, a temperature of 120.degree. C. and a dew point of 5.degree. C. for 5 minutes.

Polymer latexes produced as described in Synthesis Examples 1 to 6 and a latex of butyl acrylate-styrene-methacrylic acid-diacetone acrylamide copolymer (ratio by weight: 60.04 : 3.7 : 6.2 : 30.02) described in Japanese Patent Application (OPI) 22935/74 for comparison (hereinafter called Latex P, to which polyacrylamide was added in an amount of 2% by weight based on the latex solid content) were applied under conditions shown in Table 1 below. The coater used was a spiral rod coater having a pitch of 0.8 mm. The drying air had a velocity of 2 m per second and a dew point of 5.degree. C.

Each of the thus-produced photographic elements for evaluation was placed face-to-face with a pH indicator coating film prepared by the method described in (III) below and an alkaline viscous solution prepared by the method shown in (IV) below was spread between them in a liquid thickness amount of 120 .mu.. Then, the optical density was measured on the pH indicator coating film. The period of time required for reducing by half the reflection density of the high pH color (blue) of Thymolphthalein by neutralization (this period of time is presumed to be the period of time for reaching a pH of 10) at 25.degree. C. and that at 15.degree. C. were measured. The results of the tests are shown in Table 2 below.

To a polyethylene terephthalate film having a thickness of 180 .mu., a 7% solution of gelatin containing 28.5 mg of Thymolphthalein per g of gelatin (solvent: a mixture of water - methanol (4:1 by volume) was applied in an amount of 100 g per square meter to form a film having a thickness of about 6.5 .mu.. To the resulting film, a dispersion of titanium dioxide (solid content 10%) composed of 9 g of titanium dioxide per g of gelatin was applied in an amount of 300 g per square meter to form a white film having a dry thickness of about 9 .mu.. Further, to the resulting film, the same solution of gelatin containing Thymolphthalein as described above was applied in the same manner and dried to complete the application.

30 g of hydroxyethyl cellulose (Natrosol 250-HR, produced by Hercules, Inc.) and 30 g of sodium hydroxide were dissolved in 940 g of water with stirring and the solution was used after defoaming.

As is clear from a comparison of the values shown in Table 2 above, if the timing layer of the present invention is used, the value of T.sub.15 /T.sub.25 (%) is quite large in comparison with the use of the prior art timing layer. Namely, the water permeability markedly increases as the temperature increases, while the time at a high pH is prolonged on the low temperature side.

To a polyethylene terephthalate film having a thickness of 100 .mu., a neutralizing layer was applied using the method shown in (V) below and a cellulose acetate timing layer was applied to the resulting neutralizing layer using the method (VI) below. Further, to the resulting layer, a timing layer of the present invention was applied in the same manner as in (II) of Example 1 to produce photographic elements as shown in Table 3 below. Using these photographic elements for evaluation, the neutralizing rate of the alkali component in the viscous alkaline processing solution was measured in the same manner as in Example 1. Results obtained are shown in Table 3 below.

As can be understood from a comparison of the values shown in Table 3 above, if the timing layer of the present invention is used, the value of T.sub.15 /T.sub.25 (%) markedly increases as in Example 1.

3.8 g of 5-(2-cyanoethylthio)-1-phenyltetrazole was dissolved in 1 kg of a 20% solution of acrylic acid-butyl acrylate copolymer (molar ratio 8:2) having an average molecular weight of 50,000 (solvent: acetone-water 3:1 (by volume)). This solution was applied in an amount of 110 g per square meter using an extrusion coater and dried with dry air having a velocity of 5 m per second, a temperature of 120.degree. C. and a dew point of 5.degree. C. for 5 minutes to obtain a film having a thickness of about 20 .mu..

55 g of cellulose acetate having an acetylation degree of 52.1% (weight of acetic acid released by hydrolysis: 0.521 g per g of sample) (LM-70 produced by Daisel Ltd.) and 5 g of a styrene-maleic acid anhydride copolymer (molar ratio 1:1) having an average molecular weight of 10,000 were dissolved in a solvent mixture of acetone and cyclohexanone (vol ratio of 3:1). This solution was applied to the neutralizing layer produced by the method shown in (V) above in an amount of 50 g or 150 g per square meter using an extrusion coater and dried with dry air having a velocity of 4 m per second, a temperature of 80.degree. C. and a dew point of 5.degree. C. to obtain a film having a thickness of about 2.6 .mu. or 7.8 .mu..

The processing temperature tolerance was examined for Photographic Elements for Evaluation (cover sheet) No. 11 and No. 14 and Photographic Elements for Comparison (cover sheet) No. 15 and No. 18 using the following photosensitive sheet (an image receiving element and a photosensitive element were applied to the same support) and a processing solution (processing element).

To a transparent polyethylene terephthalate support having a thickness of 180 .mu., the following layers were provided in turn:

(1) a layer comprising a mordanting agent (3.0 g/m.sup.2) of the following formula ##STR7## and gelatin (3.0 g/m.sup.2),

(2) a layer comprising titanium dioxide (20 g/m.sup.2) and gelatin (2.0 g/m.sup.2),

(3) a layer comprising carbon black (2.5 g/m.sup.2) and gelatin (2.5 g/m.sup.2),

(4) a layer comprising cyan image forming material (0.50 g/m.sup.2) of the following formula ##STR8## diethyl laurylamide (0.25 g/m.sup.2) and gelatin (1.14 g/m.sup.2)

(5) a layer comprising a red-sensitive internal latent image type direct reversal silver iodobromide emulsion (composition of halogen in silver halide: 2% by mol iodide; amount of silver: 1.9 g/m.sup.2 ; gelatin: 1.4 g/m.sup.2), a fogging agent (0.028 g/m.sup.2) of the following formula ##STR9## and sodium dodecylhydroquinone sulfonate (0.13 g/m.sup.2),

(6) a layer comprising gelatin (2.6 g/m.sup.2) and 2,5-di-octylhydroquinone (1.0 g/m.sup.2),

(7) a layer comprising a magenta image forming material (0.45 g/m.sup.2) of the following formula ##STR10## diethyl laurylamide (0.10 g/m.sup.2), 2,5-di-t-butylhydroquinone (0.0074 g/m.sup.2) and gelatin (0.76 g/m.sup.2),

(8) a layer comprising a green-sensitive internal latent image type direct reversal silver iodobromide emulsion (composition of halogen in silver iodobromide: 2% by mol iodide; amount of silver: 1.4 g/m.sup.2 ; gelatin: 1.0 g/m.sup.2), the same fogging agent as described for layer (5) (0.024 g/m.sup.2) and sodium dodecylhydroquinone sulfonate (0.11 g/m.sup.2),

(9) a layer comprising gelatin (2.6 g/m.sup.2) and 2,5-dioctylhydroquinone (1.0 g/m.sup.2),

(10) a layer comprising a yellow image forming material (0.78 g/m.sup.2) of the following formula ##STR11## diethyl laurylamide (0.16 g/m.sup.2), 2,5-di-t-butylhydroquinone (0.012 g/m.sup.2) and gelatin (0.78 g/m.sup.2),

(11) a layer comprising a blue-sensitive internal latent image type direct reversal silver iodobromide emulsion (composition of halogen in silver iodobromide: 2% by mol iodide; amount of silver: 2.2 g/m.sup.2 ; gelatin: 1.7 g/m.sup.2), the same fogging agent as described for layer (5) (0.020 g/m.sup.2) and sodium dodecylhydroquinone sulfonate (0.094 g/m.sup.2), and

(12) a layer comprising gelatin (0.94 g/m.sup.2).

0.8 g of the processing solution having the above described composition was placed in a container which was rupturable on pressing.

The above-described cover sheet for evaluation was superposed on the above-described photosensitive sheet. After exposure to light through the cover sheet using a color test chart, the above described processing solution was spread between both sheets in a liquid thickness of 85 .mu.. (Spreading was carried out using pressing rolls.) Processing was carried out at 25.degree. C. and 15.degree. C., respectively. After processing, the blue density, the green density and the red density formed on the image receiving layer were measured through the transparent support of the photosensitive sheet using a Macbeth reflection densitometer. (The measurement was carried out after a lapsse of sufficient time for the image densities to reach equilibrium.) The values of the maximum transfer density in the optical density were shown in Table 4 below.

It can be seen from the results shown in Table 4 above that when the cover sheets of the present invention, Nos. 11 and 14, are used, sufficient transfer densities are obtained even though the processing is carried out at a low temperature. On the contrary, in using cover sheets for comparison, Nos. 15 and 18, it can be seen that the transfer densities markedly deteriorate, because the timing of stopping the development in the cover sheets is too quick notwithstanding the development and the dye formation reaction are delayed due to the temperature decrease.

Using cover sheets for evaluation No. 9, 10, 12 and 13 prepared as described in Example 2, the processing was carried out in the same manner as described in Example 3 using a combination of the photosensitive sheet and the processing solution as described in Example 3.

In using any of these cover sheets, excellent processing temperature tolerance could be obtained.

While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.