GB2038493A

GB2038493A - Photographic element for color diffusion transfer process

Info

Publication number: GB2038493A
Application number: GB7940190A
Authority: GB
Original assignee: Fuji Photo Film Co Ltd
Current assignee: Fujifilm Holdings Corp
Priority date: 1978-11-24
Filing date: 1979-11-21
Publication date: 1980-07-23
Also published as: DE2947141A1; JPS5570839A; GB2038493B; FR2442463A1; JPS6017106B2

Abstract

A photographic element, for use in the color diffusion-transfer process, includes a neutralising system which comprises (i) a neutralizing layer and (ii) a timing layer positioned on or under the neutralizing layer in direct or indirect contact therewith such that aqueous alkaline diffusion-transfer developing solution reaches the neutralizing layer during the processing of the element through the timing layer and the two layers together reduce the pH of said solution; the timing layer has been formed by coating and drying a layer of an aqueous latex of particles of a co-polymer which latex has been produced by emulsion polymerization of (a) at least one polymerizable ethylenically unsaturated monomer having at least one free carboxylic acid group or a free phosphoric acid group or salt thereof and (b) at least one other copolymerizable ethylenic monomer, using a redox type of polymerization initiator comprising an oxidizing agent and a reducing agent and in the presence of a compound of a transition metal of atomic number 21 to 30, 39 to 38, 57 to 80 or 89 or more. Preferably a third ethylenic monomer of a specified general formula is also copolymerized. The presence of the compound of the transition metal (preferably iron, copper, nickel or cerium) gives a small size to the copolymer particles in the latex and this gives a timing layer of good temperature-compensating function and good adhesion to adjacent layers. Examples of the known synthesis of the copolymer are given. The neutralizing system is coated on a film support to form a cover sheet for a conventional type of laminate integral diffusion-transfer color film unit.

Description

SPECIFICATION Photographic element for color diffusion transfer process The present invention relates to a silver halide photographic element (e.g. a film unit or a cover sheet therefor) for a color diffusion-transfer process having a timing layer for neutralization of alkaline developing solution, which layer is formed from a polymer latex.

Heretofore, in the color diffusion-transfer process, the high pH due to an aqueous alkaline developing solution is maintained for an appropriate period of time whereby a dye-imageforming material is transferred into a mordanted image-receiving layer and then decreased by an acid in a neutralizing layer to thereby interrupt the formation of a color image. Further, in a photographic element for this color diffusion transfer process, a timing layer which controls the period of time at a high pH at which the photographic element is processed based on the temperature has been provided in association with a neutralizing layer, as described by W. T.

Hanson Jr. in Photographic Sci. 8 Eng., Vol. 20, p. 155 (1976), the two layers together forming a neutralizing system.

It is advantageous, in a color diffusion-transfer process which uses a dye-image-providing material which is not diffusible initially but releases a diffusible dye as a result of an oxidationreduction reaction or a coupling reaction with an oxidation product of the developing agent as described, for example, in Japanese Patent Application (OPI) No. 33826/73 (The term "OPI'' as used herein refers to a "published unexamined Japanese patent application") and U.S.

Patents 3,929,760, 3,931,144 and 3,932,381, to provide a timing layer which has a "temperature-compensating" function. In this manner decreases in the density of transferred color images from delay in the development of silver halide, delay in the above-described oxidation-reduction reaction and delay in the diffusion of dyes at a low temperature can be corrected by prolonging the period of time under a high pH, namely, prolonging the period of time in which developing of silver halide and release and transfer of the dyes can occur.

Examples of timing layers having a '"temperature-compensating" function include timing layers composed of polyvinyl alcohol as described in U.S. Patent 3,362,819, in Japanese Patent Application (OPI) No. 22935/74 and in Research Disclosure, p. 86, Nov. 1976, e.g., timing layers formed from a latex of a methyl acrylate-vinylidene chloride-itaconic acid copolymer or of an acrylonitrile-vinylidene chloride-acrylic acid copolymer.

However, in the timing layers described in Japanese Patent Application (OPI) No. 22935/74, the delay in development cannot be adequately compensated for, because the degree of the low permeability of the timing layer at 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 a hazardous chemical compound to humans and has a low boiling point.

Furthermore, when a cover sheet including a neutralizing system and a photosensitive sheet comprising an image-receiving element and a photosensitive element coated in turn on a support are combined to form a laminate integral type film unit using a heat seal treatment which is suitable for high speed mass-production and the film unit is handled somewhat roughly, in particular, at a low temperature, the heat-sealed portion of the film unit is liable to be broken and the processing solution is liable to spread between the photosensitive sheet and the cover sheet and leak out of the film unit. In most cases the rupture of the film unit which results in the above-described instance is due to poor adhesion between the timing layer and the layers adjacent thereto.

As a result of extensive studies we have found that the temperature-compensating function and the adhesion to the adjacent layers of a timing layer are surprisingly improved by producing the polymer latex used according to the present invention using a redox type polymerization initiator in the presence of a transition metal compound.

A first object of the present invention is to provide a cover sheet which has a good temperature compensating function.

A second object of the present invention is to provide a timing layer which has a good adhesion to layers adjacent thereto even at low temperatures, and as a result provides a film unit for a color diffusion transfer process in which the peeling of the film unit does not occur when a heat seal treatment is carried out.

The present invention is applied to a photographic element having a timing layer comprising a polymer latex described below, that is a photographic element for the color diffusion transfer process including a neutralizing system for reducing the pH of an aqueous alkaline developing solution which comprises a neutralizing layer and a timing layer, wherein the timing layer is positioned on or under the neutralizing layer in direct or indirect contact therewith such that the aqueous alkaline developing solution reaches the neutralizing layer through the timing layer;; according to the invention the timing layer has been formed by coating and drying a polymer latex which has been produced by emulsion polymerization of at least one monomer selected from (a) polymerizable ethylenically unsaturated monomers having at least a free carboxylic acid group or a free phosphoric acid group or a salt thereof and (b) at least one other ethylenic monomer copolymerizable with those of class (a), using a redox type polymerization initiator in the presence of a transition metal compound.

It is preferred for the polymerization also to include at least one reactive monomer, of a third type (c), different from the groups (a) and (b), containing an ethylenic bond and an oxygen atom, of the following general formula (I):

wherein J represents a hydrogen atom, a methyl group or a

group; K represents a chlorine atom, a cyano group or J; Q represents a methylene group, a phenylene group or a direct bond; L represents an -O-G2 group or a

group; A represents a hydrogen atom, a methyl group, an -O-G3 group or an -NH-Y group; G1, G2 and G3, which may be the same or different, each represents a

group, a

group or an

Y represents a -CH20R2 group, a

R1 represents an aliphatic divalent group having 2 to 6 carbon atoms (e.g., a straight chain or branched alkylene group such as ethylene, propylene and 1,2propylene); R2 represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms (preferably 1 to 4 carbon atoms) or an acyl group;R3, R4, R5, R6 and R7, which may be the same or different, each represents a hydrogen atom or a -CH2OH group provided that all of the R3 to R7 do not represent hydrogen atoms at the same time; R 8a and R8b, which may be the same or different, each represents an alkyl group having 1 to 6 carbon atoms (preferably 1 to 4 carbon atoms), a formyl group, an acyl group, or R8a and R8b combine to form a ring; X represents a halogen atom (for example, a chlorine atom, a bromine atom); n represents an integer of 1 to 10; and m represents an integer of 2 to 8.

Examples of the acyl groups for R2, R8a and Rsb include an aliphatic acyl group having 2 to 4 carbon atoms (for example, an acetyl group, etc.).

Examples of the ring formed by combining R8a and Rsb include a 5- or 6-membered saturated heterocyclic ring (which may contain an oxygen atom, or a hetero atom in addition to the nitrogen atom, as a hetero atom).

In the above embodiment of the present invention, the monomers represents by Group (c) may be present in the polymer in an amount of about 0.5 to 40% by weight. The monomers of Group (a) may be present in the polymer in an amount of about 1 to about 12% by weight and the monomers of Group (b) may be present in an amount of about 48 to 99% by weight.

Specific examples of monomers of the general formula (I) are ("List A") glycidyl compounds and precursors thereof (for example, glycidyl acrylate, glycidyl methacrylate, glycidyl pvinylbenzoate, glycidyl crotonate, glycidyl itaconate, glycidyl maleate, glycidyl methylene malonate, glycidyl vinyl ether, acryl glycidyl ether, glycidyl-a-chloroacrylate, 2-hydroxy-3chloropropyl acrylate and 2-hydroxy-3-chloropropyl methacrylate, etc.), hydroxymethylacrylamide, hydroxymethylmethacrylamide, alkoxymethylacrylamides (for example, methoxymethylacrylamide, ethoxymethylacrylamide, butoxymethylacrylamide, hexyloxymethylacrylamide, etc.), alkoxymethylmethacrylamides (for example, methoxymethylmethacrylamide, butoxymethylmethacrylamide, etc.), acyloxymethylacrylamides (for example, acetoxymethylacrylamide, propionyloxymethylacrylamide, etc.), acyloxymethylmethacrylamides (for example, acetoxymethylmethacrylamide, etc.), dialkylaminomethylacrylamides (for example, dimethylaminomethylacrylamide, diethylaminomethylacrylamide, dibutylaminomethylacrylamide, N-methyl-N-ethylaminomethylacrylamide etc.), dialkylaminomethylmethacrylamides (for example, dimethylaminomethylmethacrylamide, dipropylaminomethylmethacrylamide, N-methyl-N-hydroxyethylaminomethylmethacrylamide, etc.), morpholinomethylacrylamide, N-(acrylamidomethyl)-#caprnlactam, N-(acrylamidomethyl)pyrrolidone, acrolein, methyl vinyl ketone, aziridinoalkyl acrylates (for example, aziridinoethyl acrylate, etc.), aziridinoalkyl methacrylates (for example, aziridinopropyl methacrylate, etc.), hydroxymethylated diacetoneacrylamides, hydroxymethylated diacetonemethacrylamides, etc.

In addition, the derivatives of acrylamides or methacrylamides as described in Makromolecu are Chemic, Vol. 57, pp. 27-51 (1962) can be used as Group (c) monomers.

When Y is a

in the general formula (I), Y represents a methylol product of a diacetoneacrylamide or a diacetonemethacrylamide. R3, R4, R5, R6 and R7 each represents a -CH2OH group or a hydrogen atom provided that all of the R3 to R7 do not represent hydrogen atoms at the same time. The methylol product generally includes a mono-, di-, tri-, tetra- or penta-methylol product. For example, the trimethylol product is a mixture including substituted products in which the degree of the substitution is 3 in which the positions substituted are different as a main component and further contains methylol products in which the degree of the substitution is 1, 2, 4 or 5, and which has an average degree of methylolation of about 3.

Of the monomers of copolymerization component (a), an unsaturated acid represented by the following general formula (il) or a salt thereof is preferred:

wherein D, E and M, which may be the same or different, each represents a hydrogen atom, a methyl group, a carboxy group, a carboxyalkylene group (an alkylene moiety having 1 to 3 carbon atoms is preferred), an alkoxycarbonyl group (the alkyl moiety has preferably 1 to 8 carbon atoms and may be a straight chain, branched chain or alicyclic alkyl group), or a -COO-R'-OPO3H2 group (wherein R' represents a straight chain or branched chain alkylene group preferably having 1 to 12 carbon atoms).

Also, D, E and M may represent a group in which the carboxy group, the carboxyalkylene group or the -COO-R'-OPO3H2 group and an alkali metal ion (preferably sodium or potassium) or ammonium ion form a salt. Further, at least one of D, E and M should be a carboxy group, a carboxyalkylene group, a -COO-R'-OPO3H2 group or a salt thereof (as described above).

Specific examples of the monomers represented by the general formula (II) include the following ("List B"): Acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, fumaric acid, methylenemalonic 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, sodium acrylate, ammonium acrylate, ammonium methacrylate, acryloyloxyalkyl phosphates (for example, acryloyloxyethyl phosphate and 3-acryloyloxypropyl-2-phosphate, etc.) and methacryloyloxyalkyl phosphates (for example, methacryloyloxyethyl phosphate (acid phosphoxyethyl methacrylate), 3-methacryloyloxypropyl-2-phosphate, 3-chloro-2-acid phosphoxy-propyl methacrylate, etc.), etc.

Although the monomers of copolymerization component (b) may be selected appropriately from ethylenic monomers which are known in the art, a monomer represented by the following general formula (III) is particularly effective:

wherein R9 represents a hydrogen atom, a methyl group or a -COOR,1 group; Rro represents a hydrogen atom, a halogen atom, a methyl group or a -(-CH2-),-COOR12 group; Z represents a hydrogen atom, an aryl group, a -COOR13 group, a cyano group, a halogen atom or an

R", R12 and R13, which may be the same or different, each represents an aliphatic group or an aryl group; and I represents 0 or an integer of 1 to 3.

The aliphatic group for R1, to R13 includes a straight chain, branched chain or cyclic alkyl group which may be substituted or unsubstituted. The alkyl group preferably has 1 to 12 carbon atoms.

Examples of the substituents for the substituted alkyl group include an alkoxy group, an aryl group, an aryloxy group, an arylalkyleneoxy group, a halogen atom, a cyano group, an acyl group, an alkylcarbonyloxy group, an arylcarbonyloxy group, an amino group (including a substituted amino group in which the substituents may be an alkyl group, an aryl group, etc., and the number of the substituents is 1 or 2), a hydroxy group, an alkoxyalkyleneoxy group, a heterocyclic residue (wherein the hetero atom is, e.g., an oxygen atom, a nitrogen atom, a sulfur atom, etc., a 5- or 6-membered ring being preferred, and the ring may be unsaturated or saturated and condensed with an aromatic ring), etc.

The aryl group for R10 is preferably a monocyclic aryl group (including a substituted phenyl group) having 6 to 12 carbon atoms. Further, the aryl group for R11 to R13 includes a substituted or unsubstituted phenyl or a naphthyl group. Examples of the substituents include an alkyl group in addition to the substituents described above for the substituted alkyl group.

Examples of the halogen atoms for R10 and Z include a chlorine atom, a bromine atom and a fluorine atom.

The monomers of Copolymerization Component (b) are not specifically limited as long as they have at least one vinyl group and are copolymerizable with the other monomer(s) present, and can be selected from, e.g. ("List C") acrylic acid esters, methacrylic acid esters, acrylamides, methacrylamides, allyl compounds, vinyl ethers, vinyl esters, vinyl heterocyclic compounds, styrenes, maleic acid diesters, fumaric acid diesters, itaconic acid diesters, olefins, crotonic acid esters, unsaturated nitriles, etc., provided they are different than the monomer of Group (a) and Group (c).

Of these monomers, acrylic acid esters, methacrylic acid esters, vinyl esters, styrenes and olefins are peferred.

Specific examples of acrylic acid esters include, for example, methyl acrylate, ethyl acrylate, n propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, 2-phenoxyethyl acrylate, 2-chloroethyl acrylate, dimethylaminoethyl acrylate, benzyl acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, phenyl acrylate, 2-hydroxyethyl acrylate, 3-hydroxypropyl acrylate, 2-hydroxypropyl acrylate, 2,3-dihydroxypropyl acrylate, ethyleneglycol diacrylate, triethyleneglycol triacrylate, trimethylolpropane triacrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, etc.

Specific examples of methacrylic acid esters include, for example, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, amyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, acetoacetoxyethyl methacrylate, chlorobenzyl methacrylate, octyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate, phenyl methacrylate, 2hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxypropyl methacrylate, ethyleneglycol dimethacrylate, triethyleneglycol dimethacrylate, trimethylolpropane monomethacrylate, pentaerythritol tri methacrylate, 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, etc.

Specific examples of vinyl esters include, for example, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxyacetate, vinyl acetoacetate, vinyl benzoate, vinyl salicylate, vinyl chlorobenzoate, etc.

Specific examples of styrenes include, for example, styrene, methyl styrene, chloromethyl styrene, trifluoromethyl styrene, acetoxymethyl styrene, methoxy styrene chlorostyrene, dichlorostyrene, trichlorostyrene, divinylbenzene, bromostyrene, etc.

Specific examples of olefines include, for example, ethylene, butadiene, isoprene, chloroprene, propylene, vinyl chloride, vinyl bromide, vinylidene chloride, vinylidene bromide, vinylidene fluoride, etc.

Specific examples of acrylamides include, for example, acrylamide, methylacrylamide, propylacrylamide, N-acryloyl piperidine, etc.

Specific examples of allyl compounds include, for example, allyl acetate, allyl benzoate, etc.

Specific examples of vinyl ethers include, for example, methyl vinyl ether, chloroethyl vinyl ether, etc.

It is preferred that at least one of the monomers of Group (b) constituting the polymer latex according to the present invention is water-insoluble. When two monomers of Group (b) are used to produce the polymer latex according to the present invention, it is preferred that the monomer used in a greater amount is water-insoluble. The term "water-insoluble" here means that the solubility of the monomer in water is 3% by weight or less at 25 C.

The transition metals, compounds of which are used in the present invention, comprise the elements in the Periodic Table of the Elements from scandium (atomic number 21) to zinc (atomic number 30), from yttrium (atomic number 39) to cadium (atomic number 48), from lanthanum (atomic number57) to mercury (atomic number 80) and actinium (atomic number 89) and elements thereabove. Preferred examples include simple or complex salts of metals selected from manganese, cobalt, nickel, iron, chromium, molybdenum, copper, tungsten, zinc, cadmium tin, cerium and titanium. Simple salts are salts of an acid such as a chloride, perchlorate, bromide, nitrate or sulfate. The complex salts are salts of transition metals coordinated with one or more organic ligands. When the coordination complex forms a cation the counter ion is the same as the above acid groups.When the complex is an anion the counter ion may be sodium, potassium, ammonium, etc. Of these compounds, water-soluble salts are particularly preferred. Specific examples of the compounds include ("List E") aquopentaamine cobalt (III) chloride, zinc chloride, cadmium chloride, chromium (il) chloride, cobalt (II) chloride, tin (II) chloride, titanium (III) or (IV) chloride, iron (II) or (III) chloride and hydrates thereof, copper (II) chloride and hydrates thereof, nickel chloride (II) and hydrates thereof, manganese (II) chloride and hydrates thereof, cobalt (II) perchlorate, nickel (II) perchlorate pentahydrate, dichlorotetraaquochromium (III) chloride dihydrate, cadmium bromide and hydrates thereof, cobalt (II) bromide and hydrates thereof, cerium bromide, cerium (III) bromide pentahydrate, iron (II) or (III) bromide and hydrates thereof, copper (II) bromide, nickel (II) bromide, manganese (II) bromide and hydrates thereof, cadmium nitrate and hydrates thereof, chromium (III) nitrate nonahydrate, cobalt (II) nitrate hexahydrate, cerium (III) or (IV) nitrate ammonium and hydrate thereof, iron (II) or (III) nitrate hydrate, copper (II) nitrate hydrate, nickel (II) nitrate hexahydrate, manganese (II) nitrate hexahydrate, potassium tungstate, ammonium hexachloro stannate (IV), potassium molybdate, zinc sulfate and hydrates thereof, cadmium sulfate and hydrates thereof, chromium (II) or (III) sulfate hydrate, cobalt (II) sulfate and hydrate thereof, tin (IV) sulfate dihydrate, cerium (III) sulfate, iron (II) or (III) sulfate hydrate, copper (II) sulfate and hydrates thereof, nickel (II) sulfate and hydrates thereof and manganese sulfate. Of these compounds, compounds of iron, copper, nickel and cerium are particularly preferred.

A suitable amount of the transition metal compound used in the production of the polymer latex according to the present invention is 10-9 to 10-4 mol per g solid content of the polymer.

When the amount used is excessive, the effects of the present invention cannot be achieved and also it is liable to adversely affect the process of forming photographic images and to degrade the qualities of photographic images ultimately obtained. A particularly preferred amount of the transition metal compound is about 10-8 to 10-6 mol per g solid content of the polymer.

In accordance with the present invention when a transition metal compound is used the emulsion polymerization speed increases and the particle size of the latex polymer is reduced.

When a so obtained emulsion dispersion is used as a timing layer, it is confirmed that the remarkable effects described in the present specification can be obtained. It is believed these effects are at least in part due to the small particle size, preferably 0.02 to 0.1 micron of the latex polymer.

The preferred monomer composition in the copolymer of the latex used in the present invention can be determined on the following considerations: (i) the latex can be prepared at low cost and with ease, (ii) the latex has good stability even when stored for a long period of time, (iii) the timing layer formed from the latex has an appropriate permeability of an alkaline aqueous solution and the permeability has the desired temperature dependency, and (iv) the timing layer has good adhesion strength to layers adjacent thereto (the adjacent layer may be a relatively hydrophobic layer formed by coating an organic solvent solution of a polymer) over a wide range of temperature.

A preferred composition of the copolymer is as follows: as a component (c), about 0.5 to about 40% by weight of e.g. glycidyl acrylate, glycidyl methacrylate, N-hydroxymethyl acrylamide or N-hydroxymethyl methacrylamide, more preferably an N-alkoxymethyl acrylamide or an Nalkoxymethyl methacrylamide; as a component (a), about 1 to about 12% by weight, more preferably about 1 to about 8% by weight of e.g. acrylic acid, methacrylic acid or itaconic acid; and as a component (b), about 48 to about 99% by weight, more preferably about 77 to about 98% by weight of at least one ethylenic monomer represented by the above-described general formula (III).

As Component (b), two or more copolymerizable components can be used, if desired. For example, in order to obtain a latex having a desired minimum film-forming temperature (described in detail hereinafter), a hard component and a soft component can be used in an appropriate ratio. In this case, a hard component is an ethylene type monomer of the general formula (III) which forms a homopolymer having a glass transition temperature of 50 C or more, for example, styrene, acrylonitrile, ethyl methacrylate, isopropyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate or methyl methacrylate is preferred.On the other hand, a soft component is an ethylene type monomer of the general formula (III) which forms a homopolymer having a glass transition temperature of 40 C or less, for example, a substituted or unsubstituted alkyl acrylate (examples of the substituents include an alkoxy group and a halogen atom), ethylene, propylene, butadiene, isoprene, vinyl chloride or vinylidene chloride is preferred.

Typical examples of preferred copolymers of aqueous latexes which can be used to form the timing layer of the present invention are illustrated below. In these examples, the specific transition metal compound and the amount thereof (mol/g of solid content of the polymer) added in synthesis of the polymer latex is indicated in the brackets. All ratios in the examples are by weight and based on the amount of each monomer added in the synthesis of the polymer latex.

(1) Styrene/n-butyl acrylate/acrylic acid/N-hydroxymethylacrylamide copolymer [ FeSO:4 ~ 7H20L4.3X10-7 ] (51.7:42.3:2:4) (2) Styrene/n-butyl acrylate/acrylic acid/N-hydroxymethylacrylamide copolymer [ FeSO4 ~ 7H2O: 1 X 10-6 ] (61:27:4:8) (3) Methyl methacrylate/n-butyl acrylate/acrylic acid / N-hydroxymethylacrylamide copolymer [ FeCI2 ~ 4H20: 5 X 10-4 ] (32:58:4:6) (4) Methyl methacrylate/n-butyl acrylate/acrylic acid/N-hydroxymethylacrylamide copolymer [ CuSO4 ~ 5H20: 3 X 10-7 ] (63:28:3::6) (5) Methyl methacrylate/acrylic acid/N-hydroxymethylacrylamide copolymer [ FeSO4 ~ 7H20: 5 X 10-7 ] (93:3:4) (6) Butyl methacrylate/acrylic acid/N-hydroxymethylacrylamide copolymer [ CuSO4 ~ 5H2O: 7 X 10-7 ] (90:4:6) (7) Sec-Butyl methacrylate/acrylic acid/N-butoxymethylacrylamide copolymer [ Cu(NO3)2 ~ 3H20: 1 X 10-6 ] (77:3:20) (8) Ethyl methacrylate/itaconic acid/hydroxymethylated diacetoneacrylamide* copolymer *(degree of hydroxymethylation: 2.5) [ CuSO4 ~ 5H20:.2X10-6 ] (95:2.5:2.5) (9) 2-Acetoxyethyl methacrylate/acrylic acid/N-ethoxymethylacrylamide copolymer [ Fe(N03)2 ~ 6H2O: 2.7 X 10-7 ] (87:3:10) (10) Ethyl acrylate/methacrylic acid/N-butoxymethylacrylamide copolymer [ (NH4)2Ce(N03)6: 5 X 10-7 ] (88:6:6) (11) Propyl methacrylate/maleic acid/N-methoxymethylacrylamide copolymer [ Ni(N03)2 6H2O: 6.5X10-7] (90:2:8) (12) Styrene/n-butyl acrylate/2-methacryloyloxyethyl phosphate/N-butoxymethylacrylamide copolymer [ FeCI3 ~ 6H20:4.2X10-7 ] (50:40:2:8) (1 3) Styrene/ethoxyethyl acrylate/acryl ic acid / N-hydroxymethylacrylamide copolymer [ CuCI2 ~ 2H20: 3 X 10-7 ] (43:43:4:10) (14) Styrene/n-propyl acrylate/itaconic acid/N-methoxymethylmethacrylamide copolymer [ FeSO4 ~ 7H20: 8.6 X 10-7 ] (40:38:8:14) (15) Styrene/n-butyl acrylate/acrylic acid/hydroxymethylated diacetoneacrylamide* copolymer *(degree of hydroxymethylation: 2.5) [ Cu(N03)2 3H2O: 7.2 X 10-7 ] (51.7:41.8:2:4.5) (16) Methyl methacrylate/butyl acrylate/acrylic acid/N-hydroxymethylacrylamide copolymer [ Ni(NO3)2 ~ 6H20:4X10-7 ] (36.1:53.9:2:8) (17) n-Butyl methacrylate/acrylonitrile/acrylic acid/N-ethoxymethylacrylamide copolymer [ FeSO4 ~ 7H20:9X10-7 ] (78:6:4:12) (18) n-Butyl methacrylate/acrylonitrile/itaconic acid/ N-hydroxymethylmethacrylamide copolymer [ FeCI2: 1X10-7 ] (79:5:2:14) (19) Styrene/n-butyl acrylate/acrylic acid/N-acetoxymethylacrylamide copolymer [ CuSO4 ~ 5H20: 6.7 X 10-7 ] (50:40:3:7) (20) Styrene/n-butyl acrylate/acrylic acid/N-(morpholinomethyl)methacrylamide copolymer [ Ce2(SO4)3: 8 X 10-# ] (48:40:4:8) (21) Vinylidene chloride/ethyl acrylate/acrylic acid/N-methoxymethylacrylamide copolymer [ FeCI2 ~ 4H20: 8 X 10-8 ] (85:8:3:4) (22) n-Butyl methacrylate/acrylic acid/glycidyl acrylate copolymer [ Cu(NO3)2 ~ 3H20: 5.6 X10-7 ] (87:3:10) (23) Methyl methacrylate/n-butyl acrylate/itaconic acid/glycidyl methacrylate copolymer [ FeCI3 ~ 6H20:4.7X10-7 ] (46:40:2:12) (24) sec-Butyl methacrylate/2-methacryloyloxyethylphosphate/glycidyl acrylate copolymer [ FeSO4 ~ 7H2O: 6 X 10-7] (80:9:11) (25) Styrene/n-butyl acrylate/acrylic acid/glycidyl acrylate copolymer [ CuSO4 ~ 5H20: 4 X 10-7] (47.9:38.1:2:12) (26) Styrene/n-butyl acrylate/acrylic acid/glycidyl acrylate copolymer [ CuCI2 2H2O : 3 X 10 - (46.8:37.2:4:12) (27) Styrene/ethoxyethyl acrylate/acrylic acid/glycidyl acrylate copolymer [ FeCI2 ~ 4H20: 7 X 10 - (43:43:4:10) (28) Styrene/n-butyl acrylate/itaconic acid/glycidyl methacrylate copolymer [ Ni(N03)2 ~ 6H20: 6 X 10-# ] (44:42:3:11) (29) Styrene/butyl acrylate/methacrylic acid/glycidyl methacrylate copolymer [ FeSO4 ~ 7H20: 1 X 10-6 ] (40:38:8:14) (30) Styrene/n-butyl acrylate/acrylic acid/glycidyl methacrylate copolymer [ FeCI2 ~ 4H20:2.7X10-7 ] (44.2:34.8:6:15) (31) Ethyl methacrylate/acrylic acid copolymer [ FeSO4 ~ 7H20: 2.2 X 10-7 ] (97:3) (32) Butyl methacrylate/acrylic acid copolymer [ FeCI2 ~ 4H20: 4 x 10-7 ] (97.5:2.5) (33) Butyl methacrylate/itaconic acid copolymer [ Fe(NO3)2: 5 x 10 - 7 ] (98:2) (34) Methyl methacrylate/butyl acrylate/acrylic acid copolymer [ CuCI2 ~ 2H20: 1.2 X 10-6 ] (50:47:3) (35) Styrene/butyl acrylate/acrylic acid copolymer [ FeSO4 ~ 7H20: 6 X 10-7] (53:43:4) (36) Styrene/ethyl acrylate/maleic acid copolymer [ CuSO4 ~ 5H20: 8.2 X 10-7 ] (54:44:2) (37) Benzyl methacrylate/butyl acrylate/methacrylic acid copolymer [ FeSO4 ~ 7H20: 7.5 X 10-7 ] (55:39:6) (38) Butyl methacrylate/N, N-diethylacrylamide/acrylic acid copolymer [ FeCI2 ~ 4H20:6.3X10-7 ] (80:17:3) (39) Vinyl toluene/ethoxyethyl acrylate/acrylic acid copolymer [ FeSO4 ~ 7H20: 5.3 X 10-7 ] (54:43:3) (40) Propyl methacrylate/ethyl acrylate/methacrylic acid/acrylic acid copolymer [ FeSO4 7H2O:7.4 X 10-7] (72:24:2:2) The polymer latex used in the present invention can be synthesized advantageously in a conventional manner with reference to the descriptions appearing in, for example, Japanese Patent Publication No. 29195/72, Japanese Patent Applications (OPI) Nos. 37488/73, 76593/73, 92022/73, 21134/74 and 120634/74, Japanese Patent Application No.

148589/76, British Patents 1,211,039 and 961,395, U.S. Patents 2,795,564, 2,914,499, 3,033,833, 3,547,899, 3,227,672, 3,290,417, 3,262,919, 3,245,932, 2,681,897 and 3,230,275, Canadian Patent 704,778, John C. Petropoulos et al., Official Digest, 33, 719-736 (1961), Sadao Hayashi, Emulsion Nyumon (Introduction of Emulsion) (1970), Souichi Muroi, Chemistry of Polymer Latex (1970), Takuhiko Motoyama, Vinyl Emulsion (1965) and Mike Shider Juang et al., Journal of Polymer Science, Polymer Chemistry Edition, 14, 2089-2107 (1976).

Needless to say, concentration of reactants, the polymerization temperature, reaction time and the like can be varied widely in accordance with the effect desired. For example, the polymerization is, in general, carried out at a temperature of 20 to 180 C, preferably 40 to 120 C, using 0.05 to 5% by weight of a redox type radical polymerization initiator and 10-9 to 10-4 mol/g of the transition metal compound and, if necessary, 0.1 to 10% by weight of an emulsifier based on the weight of monomers to be polymerized.

The redox type polymerization initiator comprises a combination of an oxidizing agent and a reducing agent and is described in Journal of Polymer Science, Vol. XXX, pp. 315-330(1958); Teiji Tsuruta, Kobunshi Gosei Hanno (Reaction and Synthesis of Polymers), Revised Ed., pp.

52-53, (Nikkankogyo Shinbunsha Co., Ltd.); Shunsuke Murahashi et al, Gosei Kobunshi I (Synthetic Polymers), p. 39 (Asakura Shoten). The oxidizing agents which can be used for the redox polymerization initiator include, for example, potassium persulfate, ammonium persulfate, sodium perphosphate, tert-butyl peroctoate, benzoyl peroxide, isopropyl peroxide, isopropyl percarbonate, 2,4-dichlorobenzoyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide and dicumyl peroxide.

The reducing agent which can be used for the redox polymerization initiator include, for example, bisulfites (such as sodium hydrogen sulfite, potassium hydrogen sulfite), primary salts of polyvalent metals (for example, ferrous salts (such as ferrous chloride, ferrous sulfate) or cuprous salts (such as cuprous chloride, cuprous sulfate)), amine compounds (such as ethanolamine, triethanolamine, polyethylene polyamine, N,N-dimethylaniline) or mercapto compounds (such as mercaptobenzothiazole, 2,4,6-trichlorothiophenol).

Of these, redox combinations of a persulfate and a bisulfite are particularly preferred in view of stability, safety, handling, economy, odorlessness, etc.

A suitable molar ratio of the oxidizing agent to the reducing agent employed is about 1/10 to about 10/1 and preferably 1:1.

When a primary salt of a polyvalent metal, in particular a primary salt of a transition metal, is used as the reducing agent in the redox polymerization initiator, a primary salt of a polyvalent metal which is different from the transition metal compound discussed earlier should be selected.

Suitable emulsifiers for polymerization include anionic, cationic, amphoteric or nonionic surface active agents and water-soluble polymers, for example, sodium laurate, sodium dodecylsulfate, sodium 1 -octoxycarbonylmethyl- 1 -octoxycarbonylmethanesulfonate, sodium laurylnaphthalenesulfonate, sodium laurylbenzenesulfonate, sodium laurylphosphate, cetyltrimethylammonium chloride, dodecyltrimethylammonium chloride, N-2-ethylhexylpyridinium chloride, polyoxyethylene nonylphenyl ether, polyoxyethylene sorbitanlauryl ester, polyvinyl alcohol, water-soluble polymers, emulsifiers described in Japanese Patent Publication No. 6190/78 and the like.

Specific synthesis examples of the polymer latexes are illustrated below. However, the present invention is not limited to these examples.

SYNTHESIS EXAMPLE 1 Synthesis of Latex Compound 5 A 1 liter 3-neck flask equipped with a stirrer, a nitrogen inlet conduit, a thermometer and a reflux condenser was placed on a water bath. 3.5 g of a 43% by weight of an aqueous solution of sodium alkylphenyl phenyl ether disulfonate (carbon number in the alkyl group of the main component is 12) and 750 ml of distilled water were put into the flask.The air in the flask was purged with nitrogen gas and the temperature in the flask was increased to 60 C. 6 g of Nmethylolacrylamide, 4.5 g of acrylic acid and 139.5 g of methyl methacrylate were added with stirring to emulsify the mixture. 20 ml of an aqueous solution containing 21 mg of ferrous sulfate heptahydrate dissolved, 20 ml of an aqueous solution containing 410 mg of potassium persulfate dissolved and 10 ml of an aqueous solution containing 160 mg of sodium hydrogen sulfite dissolved were added in this order. A polymerization reaction began immediately with the generation of heat up to about 70 C. After 2 hours, 50 ml of an aqueous solution containing 410 mg of potassium persulfate and 160 mg of sodium hydrogen sulfite dissolved was added to the mixture. After stirring for 2 hours at 60 C, the temperature was decreased to room temperature to finish the reaction. The average particle size of the polymer as measured by an electron microscope was 0.06 ju.

SYNTHESIS EXAMPLE 2 Synthesis of Latex Compound 1 3.5 g of a 43% by weight of an aqueous solution of sodium alkylphenyl phenyl ether disulfonate (carbon number in the alkyl group of the main component is 12) and 750 ml of distilled water were put into the same type of apparatus as described in Synthesis Example 1.

The air in the flask was purged with nitrogen gas and the temperature in the flask was increased to 50 C. 6 g of N-hydroxymethylacrylamide, 3 g of acrylic acid, 77.6 g of styrene and 63.4 g of butyl acrylate were added with stirring to emulsify the mixture. 15 ml of an aqueous solution containing 18 mg of ferrous sulfate heptahydrate dissolved, 25 ml of an aqueous solution containing 306 mg of ammonium persulfate dissolved and 10 ml of an aqueous solution containing 140 mg of sodium hydrogen sulfite dissolved were added in this order. A polymerization reaction began with the generation of heat up to about 55 C. After 2 hours, 50 ml of an aqueous solution containing 306 mg of ammonium persulfate and 140 mg of sodium hydrogen sulfite dissolved was added to the mixture.After the stirring had been continued at 50 C for 2 hours, the temperature was decreased to room temperature to finish the reaction.

The average particle size of the polymer as measured by an electron microscope was 0.07,u.

Other polymer latexes according to the present invention can be synthesized in a similar manner to these synthesis examples. The particle size of the polymer latexes used according to the present invention is extremely small in comparison with that of known polymer latexes. For reference, known methods for synthesis of polymer latexes (comparative synthesis examples) are shown below.

COMPARATIVE SYNTHESIS EXAMPLE 1a Latex Compound 5 was prepared in the same manner as described in Synthesis Example 1 without using 21 mg of ferrous sulfate heptahydrate. The average particle size measured by an electron microscope was 0. 14 jb.

COMPARATIVE SYNTHESIS EXAMPLE 2a Latex Compound 1 was prepared in the same manner as described in Synthesis Example 2 without using 18 mg of ferrous sulfate heptahydrate. The average particle size measured by an electron microscope was 0.12 y.

COMPARATIVE SYNTHESIS EXAMPLE 1b A latex compound was prepared in the same manner as described in Synthesis Example 1 without using 160 mg twice of sodium hydrogen sulfite. The average particle size measured by an electron microscope was 0. 16 y.

COMPARATIVE SYNTHESIS EXAMPLE 2b A latex compound was prepared in the same manner as described in Synthesis Example 2 without using 140 mg twice of sodium hydrogen sulfite. The average particle size of the copolymer measured by an electron microscope was 0. 17 fi .

The average particle size of latexes for the timing layer in the present invention is preferably about 0.02 to about 0.1 ju. (The average particle size is the number mean of the diameter of the particles measured by a microscope in a conventional manner.) The properties of the polymer latex for the timing layer in the present invention can be appropriately modified. For instance, the stability during storage of a polymer latex may be improved in the following manner: (1) By introducing a hydrophilic group into the polymer latex.

A hydrophilic group may be introduced into the polymer latex using a monomer represented by the above-described general formula (I) wherein R2 is a hydrogen atom or at least one of R3 to R7 is a -CH2OH group. More specifically, sodium hydrogensulfite may be added to the polymer latex. Another method which can be used is described in C.E. Schildknecht, Polymer Process, p. 340, lnterscience (1965).

(2) By copolymerizing (d) a monomer containing a sulfonic acid group with the monomers of Group (a), Group (b) and Group (c).

Examples of the monomers containing a sulfonic acid group include, ("List D") styrenesulfonic acid, vinylbenzylsulfonic acid, vinylsulfonic acid, acryloyloxyalkyl sulfonic acids (for example, acryloyloxymethyl sulfonic acid, acryloyloxyethyl sulfonic acid, acryloyloxypropyl sulfonic acid and acryloyloxybutyl sulfonic acid, etc.), methacryloyloxyalkyl sulfonic acids (for example, methacryloyloxymethyl sulfonic acid, methacryloyloxyethyl sulfonic acid, methacryloyloxypropyl sulfonic acid and methacryloyloxybutyl sulfonic acid, etc.), acrylamido alkyl sulfonic acids (for example, 2-acrylamido-2-methylethanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid and 2-acrylamido-2-methylbutanesulfonic acid, etc.) and methacrylamido alkyl sulfonic acids (for example, 2-methacrylamido-2-methylethanesulfonic acid, 2-methacrylamido-2-methylpropanesulfonic acid and 2-methacrylamido-2-methylbutanesulfonic acid, etc.).

In general, the amount of the hydrophilic group such as a sulfonic acid group in the polymer latex is about 0.1 to 80 mol% based on the total number of cross-linking groups such as Nmethylol groups.

The timing layer of the present invention 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 after coating another timing layer (e.g., a cellulose acetate layer) or an adhesion-improving layer, etc.

Examples of adhesion-improving layers include layers containing a hydrophilic colloid such as gelatin or polyvinyl alcohol, etc.

Also, the layer which is formed by coating the above-described reactive latex according to the present invention at a dry thickness of about 0.1 to about 1 ju may be used as an adhesionimproving layer and a known latex timing layer can be applied thereto.

In a preferred embodiment of the present invention, the timing layer is used in combination with another timing layer. Preferred examples of the ether timing layers include a timing layer produced by coating a mixture of cellulose acetate and a maleic anhydride copolymer such as a styrene-maleic anhydride copolymer, a methyl vinyl ether-maleic anhydride copolymer, a vinyl acetate-maleic anhydride copolymer as described in U.S. Patents 4,029,849 and 4,056,394, a timing layer composed of a homopolymer of a hydroxyalkyl (meth)acrylate such as hydroxyethyl acrylate or hydroxyethyl methacrylate or a copolymer of such a monomer and other copolymerizable vinyl monomers as described in Japanese Patent Publication No. 46496/77, etc. These other timing layers are used in a thickness of about 1 to 20 jb, generally.

The photographic element of the present invention may be a cover sheet, including a transparent plastic film support, containing the neutralizing layers; this sheet is used for covering the photosensitive element; or it may be a so-called integral laminated film unit which comprises a support, a photosensitive sheet comprising an image-receiving element and a photosensitive element, a cover sheet having a neutralizing system according to the present invention and a processing composition 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. An integral type film unit is preferred (including the processing composition).

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 composition is spread between an image-receiving element applied to a support and an element comprising a neutralizing layer, a timing layer (which may be two or more layers and include a timing layer according to the present invention) and a photosensitive element applied to a support in this order.

Further, the neutralizing system of the present invention may be present in the imagereceiving element, although such an embodi'ment is less preferred than the others.

The timing layer of the present invention can be formed 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 conventionally used in the latex field may be added to this latex, according to the function thereof. Specific examples are described in Product Licensing Index, Vol. 92, No. 9232 (December 1971). It is preferred to use, as described at pages 107 to 108 of the aforementioned literature, surface active agents as a coating aid, solvents facilitating film formation (for example, 2-methoxy ethanol, 2-methoxy ethanol, cyclohexanone, toluene, etc.), matting agents which are used to prevent adhesion during preparation or 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 flexibility of the film (for example, phthalic acid esters such as dibutyl phthalate or dihexyl phthalate, etc., and phosphoric acid esters such as trialkyl phosphates or tricresyl phosphate, etc.), etc. A preferred amount of the above-described surface active agents for improving wetting is about 0.05 to about 0.5% (by weight). Although the amounts of these other additives can be suitably chosen depending on the effect desired, 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.

When a solution of the polymer latex having an N-hydroxymethyl group which is a reactive group or an alkoxymethyl group which is a precursor of the hydroxymethyl group according to the present invention is coated, a condensation catalyst of the reactive group can be used. In general, the lower the pH of the coating solution is, the higher is the activity of the abovedescribed reactive group, but the stability during storage of the coating solution decreases. By converting the functional group to a precursor, for example, by alkyl etherification, an improvement in stability is achieved. A preferred pH of the coating solution is about 1 to about 6.5 and particularly about 2 to about 5. When an organic or inorganic strong acid such as ptoluene sulfonic acid or hydrochloric acid, etc., is used as the condensation catalyst of the reactive group, superior results are obtained.Further, the use of an ammonium salt of such strong acids as the condensation catalyst is preferred to provide a latex timing layer having a good adhesion property to the adjacent layers without a decrease in the pH of the coating solution. Specific examples of the ammonium salts of inorganic or organic strong acids include ammonium chloride, ammonium bromide, ammonium iodide, ammonium nitrate, ammonium-ptoluene sulfonate, etc. A preferred amount added ranges from about 0.1 to about 100 millimol and particularly about 1 to about 10 millimol per 100 g of the solid content.

Although the thickness of the timing layer of the present invention advantageously ranges from about 0.5 to about 20 #F# and particularly 2 to 8,u, there is no limitation on the thickness. It can be suitably determined according to the use of the timing layer.

A latex timing layer can be produced from a mixture of two or more latexes each having a different monomer composition. Two or more latexes each having a different minimum film forming temperature may be blended. That is, by coating a mixture of a polymer latex having a minimum film forming temperature of 35 C or less (Group I) and a polymer latex having a minimum film forming temperature of more than 35 C (Group II), a latex timing layer which is almost free from the blocking defects is provided. The term "minimum film forming temperature (MFT)" used herein is a characteristic value known to one skilled in the art, and it can be easily measured with respect to a latex having an MFT of 25 C or less by a standard testing method of American Standard Bureau, i.e., ASTM-D2354-68.Also, with reference to a latex having an MFT of more than 25 C its MFT can be measured by providing the temperature gradient at a desired temperature according to the method described in Journal of Applied Polymer Science, Vol. IV, No. 10, pp. 81-85 (1960).

Examples of latexes having an MFT of more than 35'C include polymer latexes containing 65% by weight or more of styrene or 69% by weight or more of methyl methacrylate as a copolymerizable monomer component (C) of the present invention. Examples of latexes having an MFT of 35 C or less include polymer latexes containing 36% by weight or more of n-butyl acrylate as a copolymerizable monomer component (C) of the present invention.

Further, a "blocking defect" is a defect in which the timing layer adheres to the back surface of the film when the film having the latex timing layer coated on a support as an outermost layer, or a defect in which there is undesirable adhesion to a surface of a photosensitive element after the formation of a diffusion-transfer color photographic film unit occurs.

The mixing ratio of the polymer latex of Group I and the polymer latex of Group II (I:II) is preferably 95:5 to 20:80 and particularly 30:70 to 70:30 in solid content by weight.

Furthermore, a polymer latex obtained by emulsion polymerization of each of at least one monomer selected from the monomers of Group (A) and at least one monomer selected from the monomers of Group (C) (Group Ill) and a polymer latex obtained by emulsion polymerization of each of at least one monomer selected from the monomers of Group (B) and at least one monomer selected from the monomers of Group (C) (Group IV) may be blended. In this case, it is preferred to synthesize a polymer latex of Group Ill and a polymer latex of Group IV by selecting the monomer ratio so as to be 0.5 to 40% by weight of the monomer of Group (A) and 1 to 12% by weight of the monomer of Group (B) based on solid content after blending and to blend.The mixing ratio of the polymer latex of Group Ill and the polymer latex of Group IV (III:IV) is preferably 5:95 to 60:40 and particularly 10:90 to 40:60 in solid content by weight.

To dry the timing layer of the present invention on coating, electromagnetic waves such as infrared rays, ultrasonic waves, etc., may be used. A contact heat-transmission method using a heating drum, or a method of using hot air can also be suitably utilized. In any case, it is preferred for a transparent film to be produced from the latex by applying sufficient heating to evaporate the residual water or other volatile components.

The timing layer used in 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 side of the timing layer opposite the silver halide emulsion layers to the silver halide emulsion layer side. An example of a layer which is positioned on the side opposite the silver halide emulsion layers is the neutralizing layer, or a cellulose acetate timing layer which is provided between the neutralizing layer and the latex timing layer.It is often desired to add additives to the neutralizing layer or the above-described cellulose acetate timing layer which can cause disadvantageous chemical reactions if they reach the silver halide layers at the initial stage of the development (for example, development inhibiting agents or precursors thereof (development inhibitor releasing couplers and hydroquinones, and compounds which release a development inhibitors by hydrolysis as described in French Patent 2,282,1 24) or reducing agents which prevent fading). By application of the timing layer of the present invention, it becomes possible to isolate these additives so that they do not reach the silver halide emulsion layers at the initial stage of the development and to time their diffusion such that they function after sufficient development has progressed.Of course, it is also possible to control the effect of these additives with temperature.

For e"---#mpIe, when a development inhibiting agent or a precursor thereof is added to the neutralizing layer or the above-described cellulose acetate timing layer, development is not inhibited at the beginning of the development at any temperature but it is inhibited after sufficient development has progressed until finally development is stopped. Accordingly, it becomes possible to prevent the occurrence of stains or prevent an increase in image density by excessive development. Particularly, when the development temperature is high, stain easily occurs due to excessive development, since the development rate is high. In such a case, if the latex 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 (DIR) type couplers which can be used herein, include those described in, for example, U.S. Patents 3,227,554, 3,617,291, 3,701,783, 3,790,384 and 3,632,345, German Patent Application (OLS) Nos. 2,414,006, 2,454,301 and 2,454,329, British Patent 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. Patents 3,297,445 and 3,379,529 and German Patent Application (OLS) No. 2,417,914.

When the latex 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 and a reduction in the transfer image densities which is hitherto liable to occur is nearly completely corrected.

Further, when the timing layer of the present invention is used, the water permeability markedly increases as the temperature increases and it is possible to increase the water permeation rate about 2.5 to about 6 times for every 10 C increase in temperature where the temperature of measurement is varied in a range from room temperature to higher temperatures In this regard, 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 delayed neutralization of processing solution, namely, the formation of excess transfer images can be prevented.Thus, when the timing layer of the present invention is used, a temperature compensating effect is obtained, that is, a fixed transfer image density is obtained in spite of a variation in the processing temperature.

Further, since the timing layer used in the present invention has a greatly improved film strength and adhesion to the adjacent layers, the timing layer per se does not split and it does not split at the interfaces between adjacent layers when mechanical action is applied from outside to heat seal the element. Therefore, peeling of the film unit during manufacture or at the time when a processing solution is spread after photographing is prevented.

Further, the adhesion strength of the timing layer after heat sealing using a hot melt type adhesive is extremely high from room temperature to a low temperature of about 0 C and thus the timing layer of the present invention is particularly suitable for high speed mass-production of film units utilizing a heat seal treatment system.

As a hot-melt type adhesive described above, any hot-melt type adhesive conventionally known can be used. In this case, the heat seal treatment is carried out by contacting a support coated with a hot-melt type adhesive with the timing layer of the photographic element according to the present invention in a face-to-face relationship and placing them between preheated metal blocks. As hot-melt type adhesives, it is particularly advantageous to use polyethylene-vinyl acetate type adhesives, adhesives described in Research Disclosure, Vol. 158, No. 15839 (June, 1977), etc., if necessary, coated on both sides of a polyethylene terephthalate film, a polycarbonate film or a triacetyl cellulose film, etc. The strength against peeling off after the heat seal treatment can be easily determined using a conventional stretching tester.

Furthermore, there is the advantage that the cost of production is low, because the latex used in the present invention can be produced from inexpensive starting materials using simple equipment.

Evaluation of the advantages and usefulness of the timing layer of the present invention which has a characteristic that water permeability markedly increases as the temperature increases can be carried out by observing the correlation between the variation in the photographic development rate with temperature and the variation in water permeability with temperature.

The water-permeability of the timing layer is preferably described in terms of the time required for the pH of an alkaline processing solution to decrease upon passing through the timing layer and being absorbed in the neutralizing layer at a given temperature. 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 considerable correspondence between the temperature-dependence pattern of the "neutralizingtiming" and the temperature-dependence of the maximum densities of transferred image. The time required for a pH of 10 to be reached can be preferably measured using a pH indicating dye which does not decompose under alkaline conditions. It is particularly preferred to measure the time using a Thymolphthalein dye whose color changes at a pH of 10 as the pH indicator as described in Example 1 hereinafter.

When the variation in the time it takes the pH of an alkaline processing solution to decrease to a pH of 10 with temperature is measured for the timing layer of the present invention and prior art timing layers using Thymolphthalein as a pH indicator as shown in Example 1 of the present invention, it has been found that there is a considerable relationship between a variation in time with temperature to a variation of image transfer densities with temperature.It is preferred for the measurement temperature to be 25 C which is a normal temperature and 15 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 1 5"C to that at 25 C, namely T,S/T25 (T15 and T25 are each the time required for reaching a pH of 10 at 15 C or at 25 C).

It is preferred for the value of T,5/T25 measured according to the method described in Example 1 given hereinafter to be in the range of about 2.5 to about 6.0 and particularly 3.0 to 5.0.

The silver halide emulsions which can be used in the present invention are hydrophilic colloid dispersions of silver chloride, silver bromide, silver chlorobromide, silver iodobromide, silver chloroiodobromide or a mixture thereof. Although the composition of the halides is suitably selected depending on the purpose of the light-sensitive materials or the processing conditions, a silver iodobromide or silver chloroiodobromide having an iodine content of about 1 mol% to about 10 mol% (a chloride content of about 30 mol% or less) and the balance of bromide is particularly preferred. 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.Patents 2,497,875, 2,588,982, 3,456,953, 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.

Suitable color image-providing materials for the diffusion transfer process used in combination with the photographic emulsions are the compounds described in, for example, U.S. Patents 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 Patents 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. 114424/74, 126332/74, 33826/73, 126331/74, 115528/75, 113624/76, 104343/76, 114930/76, 8827/77, 23628/78, Japanese Patent Application Nos. 58318/77, 64533/77, 74601/77 and 131278/77, etc.Particularly, color image-providing materials which are not diffusible initially but release a diffusible dye as a result of an oxidation-reduction with an oxidation product of the developing agent (hereinafter referred to as DRR compounds) are preferred.

Specific examples of DRR compounds include 1 -hydroxy-2-tetramethylenesulfamoyl-4- [ 3'- methyl-4'-(2"-hydroxy-4"-methyl-5"-hexadecyloxyphenylsulfamoyl)phenylazo ] -naphthalene as a magenta dye image4orming material, and 1 -phenyl-3-cyano-4- (3'- [ 2"-hydroxy-4"-methyl-5"- (2"', 4"'-di-t-pentylphenoxyacetamido)phenylsulfamoyl ] phenylazo) -5-pyrazolone as a yellow dye 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 cross-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,Ndiethyl-p-phenylenediamine and 3-methoxy-N-ethoxy-p-phenylenediamine, etc.

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

The direct reversal photographic emulsions used in the present invention can be used to form positive images directly by conducting the developing in the presence of a fogging agent after imagewise exposing to light or by applying a uniform exposure (a high illuminance exposure for a short time, namely, exposure for 10-2 second or less, or low illuminance exposure for a long time) in surface development processing after imagewise exposing to light; as described in U.S.

Patent 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. Patents 2,588,982 and 2,568,785, hydrazides and hydrazones described in U.S. Patent 3,227,552, and quaternary salt compounds described in British Patent 1,283,835, Japanese Patent Publication No.

38164/74 and U.S. Patents 3,734,738, 3,719,494 and 3,615,615.

The amount of the fogging agent used here can be widely varied depending on the results required.''Vhere the fogging agent is added to the ligf-|Z-seilsitive materials, although the amount varies depending on the fogging agent used, the fogging agent is generally used in a range of about 0.1 mg to about 1,500 mg/mol of Ag and preferably 0.5 mg to 700 mg/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 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 image can also be obtained using a DIR reversal emulsion process as described in U.S. Patents 3,227,551, 3,227,554 and 3,364,022 or a reversal emulsion process by dissolution physical development as described in British Patent 904,364.

Processes for forming color diffusion-transfer images are described in U.S. Patents 3,227,550 and 3,227,552 and British Patent 1,330,524, etc.

Typical color developing agents which can be used with diffusible dye releasing type couplers (DDR couplers) in the present invention are p-phenylenediamine derivatives described in U.S.

Patents 3,227,552, 2,559,643 and 3,813,244. Further, paminophenol derivatives as described in Japanese Patent Application (OPI) No. 26134/73 can be advantageously used.

The image-receiving element should have a mordanting layer composed of a mordanting agent such as poly-4-vinyl pyridine latex (particularly, in polyvinyl alcohol) as described in U.S.

Patent 3,148,061, polyvinylpyrrolidone as described in U.S. Patent 3,003,872 and polymers containing quaternary ammonium salt groups or phosphonium salt groups as described in U.S.

Patents 3,239,337, 3,547,649, 3,709,690, 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.

Patents 2,882,156, 3,625,694 and 3,709,690 are also effective as mordanting agents. In addition, mordanting agents described in U.S. Patents 2,484,430, 3,958,995, 3,271,147, 3,184,309 and 3,271,147, etc., are effective.

The photographic element of the present invention has a support which does not undergo any marked dimensional change during processing. Examples of such supports include those used in conventional photographic light-sensitive materials, such as cellulose acetate films, polystyrene films, polyethylene terephthalate films and polycarbonate films; in addition, examples of effective supports include paper and laminated paper, whose surface is laminated with a water impermeable polymer such as polyethylene.

Typical examples of preferred acid materials composing the neutralizing layer used in the presnt invention include materials described in U.S. Patents 2,983,606, 2,584,030, 3,362,819, 3,765,885 and 3,819,371 and French Patent 2,290,699. Specific examples are polymethacrylic acid, a copolymer of acrylic acid and methacrylic acid having various copolymerization ratios, a copolymer of acrylic acid or methacrylic acid with other vinyl type monomer (for example, an acrylic acid ester, a methacrylic acid ester, a vinyl ether, an acrylamide, a methacrylamide, etc.) having various copolymerization ratios (preferably having 50 to 90 mol% of acrylic acid or methacrylic acid), and the like. Of these polymers, polyacrylic acid and acrylic acid-butyl acrylate copolymer are recommended to use.The neutralizing layer may contain polymers such as cellulose nitrate or polyvinyl acetate and a plasticizer as described in U.S.

Patent 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 2-methoxy ethanol. 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 alkali metal salts, alkaline earth metal salts or amines such as lithium hydroxide, sodium hydroxide, potassium hydroxide, a dispersion of calcium hydroxide, tetramethylammonium hydroxide, sodium carbonate, trisodium phosphate or diethylamine, etc. It is preferred to add a caustic alkali in such a concentration that the pH becomes about 10 or more and preferably 12 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 1,000 poises at room temperature which facilitates uniform spreading of the composition upon processing but also forms a nonfluid film to help unify the film unit after processing when the processing composition is 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 images 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 TiO2, carbon black or a pH indicator or desensitizing agent as described in U.S. Patent 3,579,335 in order to prevent fogging of the silver halide emulsion by outside light during processing. 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. Patents 2,543,181, 2,643,886, 2,653,732, 2,723,051, 3,056,491, 3,056,492 and 3,152,515, etc.

When the photographic element of the present invention is a photographic film unit, namely, a film unit capable of being processed by passage through a pair of opposing pressure applying members, the film unit preferably comprises the following elements: (a) at least one light-sensitive silver halide emulsion layer associated with a dye imageproviding substance coated on a support (photosensitive element), (b) image-receiving layer (image-receiving element), (c) alkaline processing composition, preferably contained in a rupturable container set in the interior of the film unit, and containing a silver halide developing agent, and (d) a combination of a neutralizing layer for neutralizing the alkaline processing composition and a latex timing layer according to the present invention (neutralizing system).

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

EXAMPLE 1 On a polyethylene terephthalate film having a thickness of 100 ls, a neutralizing layer prepared in the following manner (I) and a cellulose acetate timing layer prepared in the following manner (II) were applied in turn.

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

(II) Coating of Cellulose Acetate Timing Layer 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) (marketed under the designation LM-70 by Daisel Ltd.) and 5 g of a styrene-maleic acid anhydride copolymer (molar ratio of monomers 1:1) having an average molecular weight of 10,000 were dissolved in a solvent mixture of 3 parts by volume of acetone and 1 part of cyclohexanone. This solution was applied by an extrusion coater to the neutralizing layer produced in step (I) above, in an amount of 50 g per square meter and dried with dry air having a velocity of 4 m per second, a temperature of 80 C and a dew point of 5 C, to obtain a film having a thickness of 2.6 y.

Two samples of the material were taken and, on the timing layer made in step (II), there was coated a mixture of polymer latex of the type and amount shown in Table A, and the coating was dried at 70 C for 3 minutes and then at 120 C for 5 minutes to prepare a timing layer used according to the present invention or a comparison layer.

TABLE A Polymer Latexes Produced according Dry Thickness to Synthesis of Latex Cover Sheet No. Example Nos. Timing Layer (s) 1 (Invention) (1) and (5) [ 6:4 (weight ratio) ] 2.5 2 (Comparison) (2a) and (1a) [6:4 (weight ratio) ] 2.5 Each of Cover Sheets Nos. 1 and 2 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 byl.~e method shown in (IV) below was spread between them in a liquid thickness of 85 Il. Then, the optical density on the pH indicator coating film was measured.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 C and that at 15 C were measured. The results of the tests are shown in Table B below.

(III) Production of pH Indicator Coating Film To a polyethylene terephthalate film having a thickness of 180 C4, 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 y. 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 IL Further, to the resulting film, the same solution of gelatin containing Thymolphthalein described above was applied in the same manner and dried to complete the application.

(IV) Preparation of Viscous Alkaline Processing Solution 30 g of hydroxyethyl cellulose (Natrosol 250-HR; "Natrosol" is a registered Trade mark 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 B below, where the timing layer of the present invention is used the temperature dependency of the alkaline permeability is greater than that of a comparison timing layer.

TABLE B Cover Neutralizing Time (minute) Sheet No. 25'C(T25) 15'C(T15) T15/T25 1 9.54 50.3 5.27 2 9.51 33.4 3.51 EXAMPLE 2 Processing temperature tolerance was examined for the photographic elements (Cover Sheet Nos. 1 and 2) prepared in Example 1, using the following photosensitive sheet (an imagereceiving element and a photosensitive element applied to the same support) and a processing solution (processing element).

Production of Photosensitive Sheet To a transparent polyethylene terephthalate support having a thickness of 180 , the following layers were provided in turn: (1) a layer comprising a mordanting agent (3.0 g/m2) of the following formula:

and gelatin (3.0 g/m2) (2) a layer comprising titanium dioxide (20 g/m2) and gelatin (2.0 g/m2) (3) a layer comprising carbon black (2.5 g/m2) and gelatin (2.5 g/m2) (4) a layer comprising cyan image-forming material (0.50 g/m2) of the following formula:

diethyl laurylamide (0.25 g/m2) and gelatin (1.14 g/m2) (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/m2; gelatin: 1.4 g/m2), a fogging agent (0.028 g/m2) of the following formula:

and sodium pentadecylhydroquinone sulfonate (0.13 g/m2) (6) a layer comprising gelatin (2.6 g/m2) and 2,5-dioctyl-hydroquinone (1.0 g/m2) (7) a layer comprising a magenta dye image-forming material (0.45 g/m2) of the following formula: 5 10 15 20 25 30 35 40

diethyl laurylamide (0.10 g/m2), 2,5-di-t-butylhydroquinone (0.0074 g/m2) and gelatin (0.76 9/m2) (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/m2, gelatin: 1.0 g/m2), the same fogging agent as described for layer (5) (0.024 g/m2) and sodium pentadecylhydroquinone sulfonate (0.11 g/m2) (9) a layer comprising gelatin (2.6 g/m2) and 2,5-dioctyl-hydroquinone (1.0 g/m2) (10) a layer comprising a yellow image-forming material (Q.78 g/m2) of the following formula:

diethyl laurylamide (0.16 g/m2), 2,5-dit-butylhydroquinone (0.012 g/m2) and gelatin (0.78 9/m2) (11) a layer comprising a blue-sensitive internal latent image type direct-reversal silver iodobromide emulsion (composition of halogen in silver iodobromide: 2 mol% iodide; amount of silver: 2.2 g/m2; gelatin: 1.7 g/m2), the same fogging agent as described for layer (5) (0.020 g/m2) and sodium pentadecylhydroquinone sulfonate (0.094 g/m2), and (12) a layer comprising gelatin (0.94 g/m2) Processing Solution: 1-Phenyl-4-methyl-4-hydroxymethyl- 10 g pyrazolidinone Methylhydroquinone 0.18 g 5-Methylbenzotriazole 4.0 g Sodium Sulfite (anhydrous) 1.0 g Sodium Carboxymethylcellulose 40.0 g Carbon Black 150 g Potassium Hydroxide (28% aq. soln.) 200 cc H20 550 cc 0.8 g of the processing solution having the above-described composition was placed in a container which was rupturable on pressing.

Processing For evaluation, the above-described cover sheet No. 1 or 2 was superposed on the gelatin layer (12) of a piece of the above-described photosensitive sheets. 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 78 sss. (Spreading was carried out using pressing rolls.) Processing was carried out at 35 C, 25 C and 1 5 C, on different samples.After processing, the blue density, the green density and the red density formed on the imagereceiving layer were measured through the transparent support of the photosensitive sheet using a Macbeth (registered Trade Mark) reflection densitometer. (The measurement was carried out after a lapse of sufficient time for the image densities of reach equilibrium.) The values of the maximum transfer density when they reached the fixed optical density are shown in Table C below.

It can be seen from the results shown in Table C that Cover Sheet 1 provides a high transfer density at 15 C in comparison with Cover Sheet 2.

Further, where the cover sheets were used for photographing a person as a model, Cover Sheet 1 according to the present invention showed superior processing temperature tolerance (a temperature ranging from 15 to 35 C) to Cover Sheet 2.

TABLE C Processing at 25 C Difference of Density Difference of Density Cover Blue Green Red between 15 C and 25 C between 25 C and 35 C Sheet Density Density Density No. (Ds) (DG) (DR) ADB ADG ADR ADB ADG ADR ; ; 1 1.82 2.00 2.08 0.01 ~0.02 0.03 0.01 ~0.03 0.00 2 1.80 2.05 2.15 0.12 0.15 0.09 0.02 -0.04 -0.02 (comparison) ADB = DB (25'C) - DB (15 C) or DB (35'C) - DB (25 C) ADG and ADR were determined in the same manner.

Claims

1. A photographic element for use in the color diffusion-transfer process which element includes a neutralising system which comprises (i) a neutralizing layer and (ii) a timing layer positioned on or under the neutralizing layer in direct or indirect contact therewith such that the aqueous alkaline diffusion-transfer developing solution reaches the neutralizing layer during the processing of the element through the timing layer and the two layers together serve to reduce the pH of said solution, wherein the timing layer has been formed by coating and drying a layer of an aqueous latex of particles of a co-polymer which latex has been produced by emulsion polymerization of (a) at least one polymerizable ethylenically unsaturated monomer having at least one free carboxylic acid group or a free phosphoric acid group or salt thereof and (b) at least one other copolymerizable ethylenic monomer, using a redox type of polymerization initiator comprising an oxidizing agent and a reducing agent and in the presence of a compound of a transition metal of atomic number 21 to 30, 39 to 38, 57 to 80 or 89 or more.

2. A photographic element as claimed in Claim 1, wherein the transition metal compound is present in an amount of 10-9 to 10-4 mol per gram of solid content of the polymer.

3. A photographic element as claimed in Claim 1 or 2, wherein the transition metal is manganese, cobalt, nickel, iron, chromium, molybdenum, copper, tungsten, zinc, cadium, tin, cerium or titanium.

4. A photographic element as claimed in Claim 1, 2 or 3, wherein the type (a) monomer is represented by the general formula:

wherein D, E and M each represents a hydrogen atom, a methyl group, a carboxy group, a carboxyalkylene group, an alkoxycarbonyl group or a -COO-R'-OPO3H2 group or the carboxy group, the carboxyalkylene group or the -COO-R'-OPO3H2 group represented by D, E and M forms a salt with an alkali metal ion or an ammonium ion, and at least one of D, E and M is the carboxy group, a carboxyalkylene group, a -COO-R'-OPO3H2 group or a salt thereof and R' represents an alkylene group.

5. A photographic element as claimed in any preceding claim, wherein the type (b) monomer is represented by the general formula:

wherein R9 represents a hydrogen atom, a methyl group or a -COOR" group; R10 represents a hydrogen atom, a halogen atom, a methyl group or a -(CH2),COOR,2 group; Z represents a hydrogen atom, an aryl group, a -COOR,3 group, a cyano group a halogen atom or an -O-CO-R,3 group; and R,1, R12 and R13, may be the same or different and each represents an aliphatic group or an aryl group; and 1 represents 0, 1, 2 or 3.

6. A photographic element as claimed in any preceding claim, wherein the copolymer also includes (c) at least one monomer represented by the following general formula:

wherein J represents a hydrogen atom, a methyl group or a

K represents a chlorine atom, a cyano group or J; Q represents a methylene group, a phenylene group or a direct bond; L represents an -O-G2- group or a

A represents a hydrogen atom, a methyl group, an -O-G3 group or an -NH-Y group; G1, G2 and G3 each represents a

group, a

group or an

Y represents a -CH2OR2 group, a

R, represents an aliphatic divalent group having 2 to 6 carbon atoms; R2 represents a hydrogen atom, an alkyl group having 1 to 12 carbon atoms or an acyl group;R3, R4, Rsl R6 and R7 each represent hydrogen atom or a -CH2OH group provided that all of 65 R3 to R7 do not represent hydrogen atoms at the same time; R8a and Rsb each represents an alkyl group having 1 to 6 carbon atoms, a formyl group, an acyl group or R8a and R8b combine to form a ring; X represents a halogen atom; n represents an integer of 1 to 10; and m represents an integer of 2 to 8.

7. A photographic element as claimed in Claim 6, wherein the monomer of Group (a) is present in an amount of 1 to 12 weight %, the monomer of Group (b) is present in an amount of 48 to 99 weight % and the monomer of Group (c) is present in an amount of 0.5 to 40 weight %.

8. A photographic element as claimed in Claim 7, wherein said amounts by weight are respectively (a) 1 to 8%. (b) 77 to 98% and (c) 0.5 to 40%.

9. A photographic element as claimed in Claim 6, 7 or 8, wherein the monomer of Group (a) is acrylic acid, methacrylic acid or itaconic acid and the monomer of Group (c) is glycidyl acrylate, glycidyl methacrylate, N-hydroxymethylacrylamide, N-hydroxymethyl-methacrylamide, an N-alkoxymethylacrylamide or an N-alkoxymethylmethacrylamide.

10. A photographic element as claimed in Claim 5 or any of Claims 6 to 9 as dependent thereon, wherein the monomer represented by the general formula (II) is a mixture of a first monomer which forms a homopolymer having a glass transition temperature of 50 C or more and a second monomer which forms a homopolymer having a glass transition temperature of 40 C or less.

11. A photograhic element as claimed in Claim 10, wherein said first monomer is styrene, acrylonitrile, ethyl methacrylate, isopropyl methacrylate, tert-butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate or methyl methacrylate and said second monomer is a substituted or unsubstituted alkyl acrylate, ethylene, propylene, butadiene, isoprene, vinyl chloride or vinylidene chloride.

12. A photographic element as claimed in any preceding claim, wherein said polymer latex additionally contains (d) a monomer containing a sulfonic acid group.

13. A photographic element as claimed in any preceding claim, wherein the hydrophilic group content of said polymer latex is 0.1 to 80 mol % based on the total amount of crosslinking groups in the polymer.

14. A photographic element as claimed in any preceding claim, wherein said monomers are selected respectively from those named hereinbefore in List A, List B, List C and List D.

15. A photographic element as claimed in any preceding claim, wherein the transition metal compound was used in the polymerization in an amount of 10-8 to 10-6 mol per gram of solid polymer.

16. A photographic element as claimed in any preceding claim, wherein said transition metal compound is a compound different from the reducing agent of the initiator.

17. A photographic element as claimed in any preceding claim, wherein the transition metal compound is a compound of iron, copper, nickel or cerium.

18. A photographic element as claimed in any preceding claim, wherein the transition metal compound is any of those listed hereinbefore in List E.

19. A photographic element as claimed in any preceding claim, wherein said oxidizing agent is selected from potassium persulfate, ammonium persulfate, sodium perphosphate, tert-butyl peroctoate, benzoyl peroxide, isopropyl peroxide, isopropyl percarbonate, 2,4-dichlorobenzoyl peroxide, methyl ethyl ketone peroxide, cumene hydroperoxide and dicumyl peroxide.

20. A photographic element as claimed in any preceding claim, wherein said reducing agent is bisulfite, a primary salt of a polyvalent metal, a cuprous salt, an amine or a mercapto compound.

21. A photographic element as claimed in Claim 20, wherein said redox type polymerization initiator is a combination of a persulfate and a bisulfite.

22. A photographic element as claimed in any preceding claim, wherein the molar ratio of the oxidzing agent to the reducing agent is 1:10 to 10:1.

23. A photographic element as claimed in any preceding claim, wherein the number mean diameter of the particles of the copolymer in the aqueous latex was 0.02 to 0. 10 micron.

24. A photographic element as claimed in any preceding claim, wherein the copolymer latex was any of those listed as (1) to (40) hereinbefore.

25. A photographic element as claimed in any preceding claim, wherein said neutralizing system has a T15/T25 value of 2.5 to 6.0, wherein T15 is the time required for reducing the pH of the alkaline developing solution to 10 at 15 C and T26 is the period of time required for reducing the pH of the solution to 10 at 25 C.

26. A photographic element as claimed in any preceding claim, wherein said timing layer is 0.5 to 20 microns thick.

27. A photographic element as claimed in any preceding claim, which also includes another type of timing layer.

28. A photographic element as claimed in Claim 27, wherein said other timing layer comprises cellulose acetate.

29. A photographic element as claimed in any of Claims 1 to 28, wherein said photographic element is a cover sheet for a diffusion-transfer photographic film unit.

30. A photographic element as claimed in Claim 29, wherein said cover sheet includes a transparent plastics film support.

31. A photographic element as claimed in Claim 29 or 30, substantially as hereinbefore described with reference to cover sheet No. 1 of Example 1.

32. A photographic element as claimed in any preceding claim, wherein the photographic element is a laminate integral type of film unit which comprises: a photosensitive sheet comprising an image-receiving element and a color photosensitive element coated in turn on a support, a transparent cover sheet which covers the outermost layer positioned on the support and includes said neutralizing layer and said timing layer, and a processing composition capable of being spread between said photosensitive element and said cover sheet.

33. A photographic element as claimed in Claim 32, wherein said element is a strippable element.

34. A photographic element as claimed in Claim 32 or 33, wherein said photosensitive element contains at least one silver halide photographic emulsion layer and a dye image-forming material associated therewith.

35. A photographic element as claimed in Claim 34, wherein said dye image-forming material is present in a layer adjacent said photographic emulsion layer.

36. A photographic element as claimed in Claim 34 or 35, wherein said dye image-forming material is a compound capable of being oxidized by an oxidation product of a developing agent and releasing a diffusible dye.

37. A photographic element as claimed in any of Claims 34, 35 or 36, wherein said photographic emulsion is a direct reversal photographic emulsion.

38. A photographic element as claimed in Claim 37, wherein said direct reversal photographic emulsion is an internal latent image type direct reversal photographic emulsion.

39. A photographic element as claimed in Claim 38, wherein the internal latent image type emulsion is an internal latent image type emulsion comprising a core and a shell.

40. A photographic element as claimed in Claim 38, substantially as hereinbefore described with reference to the element of Example 2 which includes Cover Sheet No. 1.

41. A color photograph obtained by the use of a photographic element as claimed in any preceding claim.