Classifications

• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
  • G03C1/00—Photosensitive materials
  • G03C1/005—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein
  • G03C1/04—Silver halide emulsions; Preparation thereof; Physical treatment thereof; Incorporation of additives therein with macromolecular additives; with layer-forming substances
  • G03C1/053—Polymers obtained by reactions involving only carbon-to-carbon unsaturated bonds, e.g. vinyl polymers

Definitions

• the present invention relates to new types of polymeric latices and their use in photographic materials.
• Coated photographic layers and complete photographic materials must comply with a number of requirements concerning physical properties. In order to avoid physical damage during manufacturing and handling a photographic material must show a sufficiently high scratch resistance. Furtheron, photographic materials must show a good flexibility so that easy handling without the occurence of creases or cracks is possible ; in other words, the materials may not suffer from brittleness especially under critical low humidity conditions. On the other hand, stickiness should be avoided. Still furtheron, photographic materials must show a good dimensional stability, meaning a minimal dimensional distorsion during processing especially during the drying phase at elevated temperature. The requirement of dimensional stability is particularly stringent for graphic arts contact materials often serving in pre-press activity as final intermediates between colour separations produced on a scanner and the exposure step onto a printing plate. Several contacts, being duplicates of different separations, have to be exposed in register on one and the same printing plate and mutually different dimensional distorsions would lead to unacceptable colour shifts on image edges in the final print.
• plasticizers As well known in the art flexibility and dimensional stability can be improved by the incorporation of so-called plasticizers. These substances can be relatively low-molecular weigth compounds, preferably containing several hydrophilic groups like hydroxyl groups, or they can be polymer latices preferably having a rather low glass transition temperature. The former are able to reduce the Tg (glass transition temperature) of the binder system itself, while the latter (the polymeric latices) result in a 2-component system with a Tg typical for the binder and a second Tg typical for the latex. In both ways the layer is kept sufficiently flexible at room temperature, even at a high hardening degree of the gelatinous layer while the required dimensional stability is assured.
• plasticizers include alcohols, dihydric alcohols, trihydric alcohols and polyhydric alcohols, acid amides, cellulose derivatives, lipophilic couplers, esters, phosphate esters such as tricresyl phosphate, glycol esters, diethylene glycol mixed esters, phthalate esters such as dibutyl phthalate and butyl stearate, tetraethylene glycol dimethyl ether, ethyl acetate copolymers, lactams, lower alkyl esters of ethylene bis-glycolic acid, esters or diesters of an alkylene glycol or a polyalkylene glycol, polyacrylic acid esters, polyethylene imines, poly(vinyl acetate) and polyurethanes, as illustrated by Eastman et al U.S.
• Low-molecular plasticizers with hydrophilic groups show the disadvantage of rendering the coated hydrophilic layer(s) of a photographic element sticky particularly at elevated relative humidity.
• photographic materials are packaged, stored and delivered in a web-like or sheet-like manner an unacceptable adherance of support parts to surface parts can occur during storage or after processing. Moreover, they are not diffusion resistant.
• plasticizers consisting of conventional polymer latices, e.g. polyethylacrylates and analogues which are widely used in commercial materials, show other drawbacks.
• the amount of latex which can be incorporated in a gelatinous layer in order to improve dimensional stability is limited because high concentrations of the latex disturb the cohesion of the gelatine matrix resulting in a decrease of the scratch resistance eventually below a critical level.
• a hydrophobic core-shell latex comprising a hard core with Tg > 70 °C and a soft shell (Tg from 25 to 60 °C), wherein the core represents at least 80 % by weight of the total polymer content of the latex particles.
• Such water dispersable latices form easily a continuous film of a polymer on any possible support. It is disclosed that the use of such core-shell latices as overcoat in photographic materials reduces the ferrotyping, i.e. reduces antistatic discharges.
• the present invention extends the teachings on improved polymer latices for use as plasticizers in photographic materials.
• a photographic material comprising a support, a subbing layer, at least one hydrophilic gelatinous silver halide emulsion layer, optionally one or more other hydrophilic gelatinous layer(s) and a core-shell latex polymer, comprising a core (co)polymer and a shell (co)polymer characterised in that
• said moieties A present in said shell (co)polymer make up between 1 and 15 % by weight of all moieties present in both said core and said shell (co)polymer and said moieties A present in said shell (co)polymer make up between 2 and 20 % of all moieties present in said shell (co)polymer.
• silver halide photographic materials comprising in one or more hydrophilic gelatinous layers a latex (co)polymer of the core-shell type comprising a (co)polymer prepared by the polymerization of at least one ethylenically unsaturated monomer, forming a core and a (co)polymer prepared by the polymerization of at least one ethylenically unsaturated monomer comprising a reactive - CH2- group and optionally one or more other copolymerizable monomer(s) forming the shell, showed favourable physical properties and combined high resistance to scratches with high dimensional stability. It was also found that such material could comprise up to 50 % by weight with respect to the hydrophilic binder (e.g.
• gelatin in one or more hydrophilic layer without (substantially) increasing the water absorption of the material.
• Low water absorption is a must for silver halide materials intended for rapid processing.
• the speed limiting step in rapid processing is, in most of the cases, the drying step (following a development and fixing step) in which the water absorbed in the silver halide photographic material has to be evaporated. Since the invention latices do not (substantially) increase the water absorption, the invention latices can be used in high amounts even in materials intented for rapid processing.
• said moieties A derived from unsaturated monomers comprsing a reactive -CH2- goup, are present in an amount between 1 and 15 % by weight of all moieties present both in said core and said shell (co)polymer and said moieties A are present in said shell (co)polymer in an amount between 2 and 20 % by weight of all moieties present in said shell (co)polymer.
• Ethylenically unsaturated monomers comprising a reactive methylene (- CH2-) group are monomers comprising a -CH2- group localized between two strongly electron withdrawing groups.
• Typical examples of a -CH2- group surrounded by strongly electron withdrawing groups are : -CO - CH2- CO- -CO - CH2- CN -CO - CH2- N- pyrazoles etc.
• monomers of group A are : 2-acetoacetoxyethylacrylate 2-cyano-N-2-propenylacetamide 5-hexene-2,4-dione 5-methyl-5-hexene-2,4-dione 2-methyl-2-propenoic acid 2-[(cyanoacetyl)-oxy]ethyl ester 2-acetoacetoxy-2,2-dimethylpropyl methacrylate 3-oxo-4-pentenoic acid, ethyl ester 3-oxo-butanoic acid, 2-[(2-methyl-1-oxo-2-propenyl)oxy]ethyl ester 2-acetoacetoxyethylmethacrylate and diacetone acrylamide.
• monomer(s) useful to form either the core or the shell of the core-shell latices according to the present invention are used in combination with monomer(s) from group A) are (meth)acrylic acid esters, mixtures of (meth)acrylic acid esters, other vinyl monomers and mixtures thereof (hereinafter referred to as monomers of group B).
• monomers of group B are (meth)acrylic acid esters, within the scope of the present invention are to be understood esters of methacrylic- and acrylic acid.
• Examples of useful monomers of group B, for use in the preparation of core-shell latices according to the present invention are : 2-Propenoic acid, methylester 2-Propenoic acid, pentyl ester 2-Propenoic acid, n-butyl ester 2-Propenoic acid, phenylmethyl ester 2-Propenoic acid, cyclohexyl ester 2-Propenoic acid, cyclopentyl ester 2-Propenoic acid, hexadecyl ester 2-Propenoic acid, 2-methylpropyl ester 2-Propenoic acid, 2-ethylhexyl ester 2-Propenoic acid, 2-(1-ethyl)pentyl ester 2-Propenoic acid, 2-(2-ethoxyethoxy)-ethyl ester 2-Propenoic acid, 2-butoxyethyl ester 2-Propenoic acid, 2-(2-methoxyethoxy)-ethyl ester 2-Propenoic
• group B monomers of group B either alone, or in combination with monomer(s) of group C (defined hereinafter) to prepare the core (co)polymer of the core-shell latex.
• group B monomers are 2-propenoic acid methyl ester, 2-propenoic acid ethyl ester, 2-propenoic acid n-butyl ester, 2-methyl-2-propenoic acid methyl ester and styrene.
• monomer(s) useful to from either the core or the shell of the core-shell latices according to the present invention in combination with monomer(s) from group A and/or monomers of group B (to form the shell) or in combination of monomers of group B to form the core, are vinyl monomers that contain anionic groups, or form such groups depending on the pH of the polymerization mixture (herinafter referred to as monomers of group C).
• vinyl monomers that contain carboxylate groups or sulphonate groups or that are capable of forming them by a variation of the pH.
• preferred vinyl monomers (group C) are : 1-Propene-1,2,3-tricarboxylic acid 2-Propenoic acid 2-Propenoic acid, sodium salt 2-Chloro-2-propenoic acid 2-Propenoic acid, 2-carboxyethyl ester 2-Methyl-2-propenoic acid 2-Methyl-2-propenoic acid, lithium salt Methylenebutanedioic acid 2-Butenedioic acid 2-Methylbutenedioic acid 2-Methylenepentendioic acid 2-Carboethoxyallyl sulfate, sodium salt 2-Propenoic acid, ester with 4-hydroxy-1-butanesulphonic acid, sodium salt 2-Propenoic acid, ester with 4-hydroxy-2-butanesulphonic acid, sodium salt 3-Allyloxy-2-hydroxypropanesulphonic acid, sodium salt 2-Meth
• Especially preferred vinyl monomers with anionic groups are 2-propenoic acid sodium salt and 2-acrylamido-2-methyl-1-propanesulphonic acid, sodium salt
• group C monomers are 2-propenoic acid sodium salt and 2-acrylamido-2-methyl-1-propanesulphonic acid, sodium salt
• monomers of group B may be prepared from a mixture of group B monomers and group C monomers.
• group C monomers in combination with group A monomers are used to form the shell (co)polymer
• core-shell latices according to the present invention comprising moieties derived from group A monomers (monomers with a reactive methylene group) in the shell (co)polymer can be added to silver halide photographic materials to serve several purposes.
• group A monomers monomers with a reactive methylene group
• the addition of polymeric latices, according to the present invention can improve either the dimensional stability of the photographic material or diminish the physical scratchability (increase the scratch resistance) of the material.
• a polymeric core-shell latex comprising a reactive methylene group in the shell, according to the present invention, comprising a core (co)polymer with Tg > 50 °C, preferably with Tg > 80 °C, and a shell (co)polymer with Tg ⁇ 30 °C, preferably with Tg ⁇ 0 °C, to one or more hydrophilic layers of a silver halide photographic material improved the dimensional stability of the material and at the same time diminished the physical scratchability of the photographic material.
• a core-shell latex comprising at least in the shell a (co)polymer with Tg ⁇ 30 °C, preferably with Tg ⁇ 0 °C.
• a core-shell latex comprising both in the core and in the shell a (co)polymer with Tg ⁇ 30 °C, preferably with Tg ⁇ 0 °C, has also proven to be beneficial.
• the Tg of both the core copolymer and the shell copolymer of the core-shell latices according to the present invention have been calculated using the formula above.
• the accuracy of the Tg, calculated as described above is ⁇ 5 °C.
• the polymeric latices according to the present invention do, whatever the Tg of core- or shell-(co)polymers, not increase the water absorption of the photographic material when added to any hydrophilic layer comprised in the photographic material, as do the control latices, not comprising reactive methylene groups.
• the shell (co)polymer comprises always moieties derived from at least one group A monomer, comprising a reactive methylene group. These moieties, derived from a group A monomer, are preferably present in 2 to 50 % by weight, most preferably in 2 to 20 % by weight, with respect to the total shell (co)polymer.
• the core accounts for 1 to 99 % by weight of the weight of the entire core-shell particle and the shell for 1 to 99 % by weight.
• core-shell latices wherein the shell accounts for 10 to 80 % by weight of the weight of the entire core-shell particle, are used according to the present invention.
• the core-shell latices according to the present invention can be prepared by an emulsion polymerization technique.
• the core is prepared by the emulsion (co)polymerization of one or more polymerizable monomers. It is advantageous that, in this step of the preparation, at least part of said monomer(s) are polymerized in a batch process.
• the so prepared (co)polymer can then directly be used as core material for the further preparation of the core-shell latex.
• To control the thickness of the core it is possible to add more of the monomer(s) constituting the core (co)polymer and polymerize these monomers further onto the orginal core prepared during the batch process.
• the monomer(s), needed to form the shell are added to the core material and further polymerized on top of said core material.
• at least one of the monomers used is an ethylenically unsaturated monomer comprising a reactive methylene (- CH2-) group.
• initiators are taken into account in general 0.05 to 5 % by weight, based on the monomers, of initiators decomposing in radicals.
• Such initiators are, e.g., organic peroxides, such as lauroyl peroxide, cyclohexanone hydroperoxide, tert.-butyl peroctoate, tert.-butyl perpivalate, tert.-butyl perbenzoate, dichlorobenzoyl peroxide, benzoyl peroxide, di-tert.-butyl peroxide, tert.-butyl hydroperoxide, cumol hydroperoxide, peroxycarbonates such as diisopropyl peroxidicarbonate, dicyclohexyl peroxidicarbonate, diisooctyl peroxidicarbonate, sulphonyl peroxides such as acetylcyclohexylsulphonyl peracetate, sulphonylhydrazides,
• Inorganic peroxides such as hydrogen peroxide, potassium peroxodisulphate and ammonium peroxodisulphate are suited as well.
• the initiators decomposing in radicals can be used alone or in combination with reducing agents or heavy metal compounds.
• Such compounds are, e.g., sodium- or potassium pyrosulphite, formic acid, ascorbic acid, thiourea, hydrazine- or amine derivatives and RONGALIT (1-hydroxymethanesulphinic acid Na-salt).
• the heavy metal compounds can be present in oil-soluble as well as in water-soluble form.
• water-soluble heavy metal compounds are silver nitrate, halides and sulphates of 2- and 3-valent iron, cobalt, nickel and salts of titanium or vanadium in low valency stages.
• oil-soluble heavy metal compounds are cobalt naphthenate and the acetylacetone complexes of vanadium, cobalt, titanium, nickel and iron.
• the emulsion polymerisations take place at temperatures between 20 and 100 °C, preferably between 40 and 85 °C.
• the amount of emulsifying agents that can be used is 0 to 20 %, preferably 1 to 5 %, based on the monomers to be polymerised.
• Anionic as well as non-ionic emulsifying agents are suited therefor.
• alkyl- and aryl sulphonates such as dodecylsulphonic acid Na-salt, the N-methyl taurinate product with oleic acid (HOSTAPON T) and sulphonated dodecylphenyl phenyl ethers (Dow FAX 2A1)
• alkyl- and aryl sulphates such as the sodium sulphate of oxethylated nonylphenol (HOSTAPAL B), poly(vinyl alcohol), oxethylated phenols, oleyl alcohol polyglycol ethers, oxethylated polypropylene glycol or natural products such as gelatine and fish glue.
• the type of photographic material in which the polymer latices are incorporated according to the present invention and its field of use is not limited in any way. It includes photographic elements for graphic arts and for so-called amateur and professional black-and-white or colour photography, cinematographic recording and printing materials, X-ray diagnosis, diffusion transfer reversal photographic elements, low-speed and high-speed photographic elements, etc.
• photographic elements for graphic arts and for so-called amateur and professional black-and-white or colour photography cinematographic recording and printing materials
• X-ray diagnosis X-ray diagnosis
• diffusion transfer reversal photographic elements low-speed and high-speed photographic elements, etc.
• the advantages of the present invention become most perspicuous when the latices are incorporated in photographic materials setting high standards to dimensional stability and physical scratchability, e.g. graphic arts contact materials as explained in the Background section.
• Several types of commercial contact materials are available.
• Duplicating materials can be of the classical dark room type but in recent times preference is given to so-called daylight or roomlight contact materials which can be handled for a reasonable period under UV-poor ambient light. Also yellow light contact materials exist which can be handled under relative bright yellow light. Very insensitive daylight types are available which have to be exposed by strongly emitting metal-halogen sources. Less insensitive types are designed for exposure by quartz light sources. The daylight materials can be of the negative working type or of the direct positive working type.
• the silver halide emulsion layer simply consists of just one layer. However double layers and even multiple layer packs are possible.
• a photographic element usually comprises several non-light sensitive layers, e.g. protective layers, backing layers, filter layers and intermediate layers (or "undercoats"). All of these layers can be single, double or multiple.
• the polymer latices of the present invention can be present in all these layers, or in several of them, or in just one of them. In principle a mixture of two or more different latices can be used, or an invention latex can be mixed with a conventional plasticizer, but for normal practice just one representative of the new types will be sufficient.
• the plasticizer (latex) is present in the emulsion layer.
• the ratio of platicizer to gelatin is in that case comprised between 0.1:1 and 1:1.
• the platicizer is present in the gelatinous emulsion layer in an amount between 10 to 75 % in weight (% w/w) with respect to the gelatin.
• the latex is preferred to use in an amount of 10 to 50 % in weight (% w/w) with respect to the gelatin present in said protective layer.
• the emulsion layer and the other hydrophilic layers can contain, according to their particular design and application, the typical and well-known photographic ingredients such as stabilizers, sensitizers, desensitizers, development accelerators, matting agents, spacing agents, anti-halation dyes, filter dyes, opacifying agents, antistatics, UV-absorbers, surfactants, gelatin hardeners such as formaldehyde and divinylsulphon.
• the typical and well-known photographic ingredients such as stabilizers, sensitizers, desensitizers, development accelerators, matting agents, spacing agents, anti-halation dyes, filter dyes, opacifying agents, antistatics, UV-absorbers, surfactants, gelatin hardeners such as formaldehyde and divinylsulphon.
• composition of the silver halide emulsion incorporated in a photographic element of the present invention is not specifically limited and may be any composition selected from e.g. silver chloride, silver bromide, silver iodide, silver chlorobromide, silver bromoiodide, and silver chlorobromoiodide.
• the photographic emulsion(s) can be prepared from soluble silver salts and soluble halides according to different methods as described e.g. by P. Glafkidès in “Chimie et Physique Photographique”, Paul Montel, Paris (1987), by G.F. Duffin in “Photographic Emulsion Chemistry", The Focal Press, London (1966), and by V.L. Zelikman et al in “Making and Coating Photographic Emulsion", The Focal Press, London (1966).
• the average size of the silver halide grains may range from 0.05 to 1.0 ⁇ m, preferably from 0.2 to 0.5 ⁇ m. For daylight materials the average grain size is preferably comprised between 0.07 ⁇ m and 0.20 ⁇ m.
• the size distribution of the silver halide particles can be homodisperse or heterodisperse.
• the light-sensitive silver halide emulsions can be chemically sensitized as described e.g. in the above-mentioned "Chimie et Physique Photographique” by P. Glafkidès, in the above-mentioned “Photographic Emulsion Chemistry” by G.F. Duffin, in the above-mentioned “Making and Coating Photographic Emulsion” by V.L. Zelikman et al, and in "Die Grundlagen der Photographischen Sawe mit Silberhalogeniden” edited by H. Frieser and published by Akademische Verlagsgesellschaft (1968).
• the emulsion is preferably not chemically ripened and can contain relative high amounts of a desensitizer.
• the light-sensitive silver halide emulsions can be spectrally sensitized with methine dyes such as those described by F.M. Hamer in "The Cyanine Dyes and Related Compounds", 1964, John Wiley & Sons.
• Dyes that can be used for the purpose of spectral sensitization include cyanine dyes, merocyanine dyes, complex cyanine dyes, complex merocyanine dyes, hemicyanine dyes, styryl dyes and hemioxonol dyes.
• Particularly valuable dyes are those belonging to the cyanine dyes, merocyanine dyes and complex merocyanine dyes.
• the emulsion is preferably not spectrally sensitized in view of the daylight stability.
• the silver halide emulsion(s) for use in accordance with the present invention may comprise compounds preventing the formation of fog or stabilizing the photographic characteristics during the production or storage of photographic elements or during the photographic treatment thereof. Many known compounds can be added as fog-inhibiting agent or stabilizer to the silver halide emulsion.
• the photographic material of the present invention may further comprise various kinds of surface-active agents in the photographic emulsion layer or in another hydrophilic colloid layer.
• Suitable surface-active agents include non-ionic agents such as saponins, alkylene oxides e.g.
• polyethylene glycol polyethylene glycol/polypropylene glycol condensation products, polyethylene glycol alkyl ethers or polyethylene glycol alkylaryl ethers, polyethylene glycol esters, polyethylene glycol sorbitan esters, polyalkylene glycol alkylamines or alkylamides, silicone-polyethylene oxide adducts, glycidol derivatives, fatty acid esters of polyhydric alcohols and alkyl esters of saccharides; anionic agents comprising an acid group such as a carboxy-, sulpho-, phospho-, sulphuric- or phosphoric ester group; ampholytic agents such as aminoacids, aminoalkyl sulphonic acids, aminoalkyl sulphates or phosphates, alkyl betaines, and amine-N-oxides; and cationic agents such as alkylamine salts, aliphatic, aromatic, or heterocyclic quaternary ammonium salts, aliphatic or hetero
• Such surface-active agents can be used for various purposes e.g. as coating aids, as compounds preventing electric charges, as compounds improving slidability, as compounds facilitating dispersive emulsification, as compounds preventing or reducing adhesion, and as compounds improving the photographic characteristics e.g higher contrast, sensitization, and development acceleration.
• Preferred surface-active coating agents are compounds containing perfluorinated alkyl groups.
• the support of the photographic material can be a transparent base, preferably an organic resin support, e.g. cellulose nitrate film, cellulose acetate film, polyvinylacetal film, polystyrene film, polyethylene terephthalate film, polycarbonate film, polyvinylchloride film or poly-Alpha-olefin films such as polyethylene or polypropylene film.
• the thickness of such organic resin film is preferably comprised between 0.07 and 0.35 mm.
• These organic resin supports are preferably coated with a subbing layer.
• the support of the photographic material can be a paper base preferably a polyethylene or polypropylene coated paper base.
• the photographic material can be exposed according to its particular composition and application, and processed by any means or any chemicals known in the art depending on its particular application.
• Average particle size 86 nm.
• Average particle size 83 nm.
• Average particle size 78 nm.
• HOSTAPAL B tradename of Hoechst AG, Germany for the sodium sulphate of oxethylated nonylphenol
• Average particle size 78 nm.
• Average particle size 77 nm.
• Average particle size 73 nm.
• Average particle size 69 nm.
• the photographic material was prepared as follows. A direct positive pure silver bromide emulsion was precipitated by a double jet technique and internally sensitized. The emulsion was then externally fogged using thiourea dioxide as to obtain the desired sensitivity. Finally the emulsion was divided in aliquot portions and different latices were added to each portion, such as to have 50 % in weight of latex polymer with respect to the gelatin present in the portions of the emulsion.
• the coating solutions thus prepared were applied to a subbed, 100 ⁇ m thick, polyethylene terephtalate base at a silver coverage, expressed as silver nitrate, of 3.18 g/m2, and a gelatin coverage of 2.7 g/m2.
• a protective layer was applied containing gelatin hardened with formaldehyde at a coverage of 0.7 g/m2.
• the dimensional change during processing is evaluated as follows. Each coated sample was conditioned in an acclimated room for at least 6 hours to a relative humidity of 30 % at 22 °C. Two holes with a diameter of 5 mm were punched at a distance of 200 mm in each film sample having dimensions of 35 mm x 296 mm. The exact interval between those holes was measured with an inductive half-bridge probe (TESA FMS100) having an accuracy of 1 ⁇ m, whereby this distance was called X ⁇ m. Subsequently the film material was subjected to processing in an automatic apparatus, a PAKO 26RA the dryer of which was equipped with an air-inlet.
• TSA FMS100 inductive half-bridge probe
• the samples were developed at 38 °C, fixed at 33 °C, rinsed without temperature control, and dried, whereby air of 22 °C and of 30 % RH was provided through the air-inlet and wherby the temperature was raised up to 55 °C.
• the distance between the two holes in the film is measured again after an acclimatisation period of 3 hours and is expressed as Y ⁇ m.
• the dimensional stability is calculated as (Y-X).5 and expressed in ⁇ m/m.
• the water absorption was measured gravimetrically.
• a dry sample of the material was accurately weighted (W1) and the without exposure processed as described above, but taken out of the processing apparatus before the dryer.
• the processed, but not dried sample of the material was weighted again (W2) and after drying the sample was weighted again (W3).
• the difference between W2 and W3 was the water absorption of the sample, i.e. the amount of water per m2 that has to be evaporated in the dryer.
• Table 3 The results are summarized in table 3.
• the water absorption, dimensional stability and physical scratchability is compared of photographic material samples comprising no plasticizer, a control plasticizer polyethylacrylate (C-1), a core-shell latex with only 1 % by weight of moieties comprising reactive methylene groups with respect to the total weight of the monomers present in both core and shell.
• the shell (co)polymer comprised only 1 % by weight (with respect to the total weight all monomers used to form said shell copolymer) of an unsaturated monomer comprising a reactive - CH2- group.
• Latices LAT3, LAT4 comprised 10 % by weight (with respect to the total weight all monomers used to form said shell copolymer) of an unsaturated monomer comprising a reactive - CH2- group.
• the photographic material was prepared as described in photographic example 1.
• the developed and dried material was passed under a stylus with a diamond ball shaped end with diameter 5 ⁇ m.
• the stylus was loaded with weights between 1 to 30 g with increments of 1 g each step going from 1 to 30 g.
• the light transmittance under scratch was measured for each increment of 1 g and correlated to the weight imposed on the stylus.
• the weight where the correlation line of transmittance versus weight crosses the weight axis is taken as a measure for physical scratchability and is expressed in g. The greater the figure, the lower the scratchability.
• invention latices in a photographic material instead of a control latex, improves the dimensional stability to the same extent as the use of a control latex, but improves the scratchability of the materials with respect to the material comprising the control latex.
• the invention latex with only 1 % of reactive methylene groups in the shell (LAT8) is less effective than the invention latices comprising more than 1 % of reactive methylene groups in the shell.
• the photographic material was a negative working material, prepared as follows : A cubic silver halide emulsion, comprising 0.4 % of iodide, 16 % of bromide and 83.4 % of chloride was prepared by a double jet emulsion technique, and doped with Ir and Rh. The average crystal diameter was 0.30 ⁇ m. To 1 kg of the gold-sulfer sensitized emulsion, containing 1.1 mole of silver halide was added a conventional substituted tetraazaindene and a conventionally substituted mercaptotetrazole. A blue spectral sensitizer was added.
• the coating solutions thus prepared were applied to a subbed, 175 ⁇ m thick, polyethylene terephthalate base at a silver coverage, expressed as silver nitrate, of 7.45 g/m2, and a gelatin coverage of 3.35 g/m2.
• a protective layer was applied containing gelatin hardened with formaldehyde at a coverage of 0.93 g/m2.
• an intermediate layer was applied with a gelatin coverage of 1 g/m2.
• invention latices to the photographic material provides a material with better scratch resistance (lower scratchability) combined with lower water absorption.
• the photographic material was the same material as described in photographic example 3, but now the latices were added to the protective layer. Before coating the coating solution for the protective layer was divided in 4 aliquot portions. To the first portion no latex was added, to the second and to the third portion invention latex LAT1 and LAT2 were added respectively. All latices were added in an amount of 35 % by weight with respect to the gelatin. The results are summarized in table 6. TABLE 6 Plasticizer 35 % in weight vs gelatin Waterabsorption in g/m2 Scratchability in g No plasticizer 6.0 8.4 LAT1 6.2 9.0 LAT2 5.8 9.1
• the photographic material was the same material as described in photographic example 3.
• the latices were added to the protective layer. Therefore the coating solution of the protective layer was divided in 4 alaquot portions.
• To the first portion no latex was added, to the second and the third portion invention latex LAT3 and LAT4 were added respectively. All latices were added in an amount of 35 % by weight with respect to the gelatin comprised in the coating solution of the protective coating.
• Table 7 TABLE 7 Plasticizer 35 % in weight vs gelatin Waterabsorption in g/m2 Dimensional stability in ⁇ m/m Scratchability in g No plasticizer 6.0 64 8.4 LAT3 6.0 54 10.0 LAT4 6.0 62 10.5
• the invention latices When added to the protective layer of a photographic material, the invention latices provide a material with equal water absorption and dimensional stability, but with a largely improved scratchability (higher scratch resistance).
• the photographic material was the same material as described in photographic example 3.
• the latices were added to the intermediate layer. Therefore the coating solution of the intermediate layer was divided in 4 alaquot portions.
• To the first portion no latex was added, to the second portion and the third portion invention latex LAT3 and LAT4 were added respectively. All latices were added in an amount of 50 % by weight with respect to the gelatin comprised in the coating solution of the intermediate layer.
• Table 8 TABLE 8 Plasticizer 50 % in weight vs gelatin Waterabsorption in g/m2 Dimensional stability in ⁇ m/m Scratchability in g No plasticizer 6.2 66 8.5 LAT3 5.9 50 9.2 LAT4 5.8 59 9.3
• a gelatinous backing layer was coated such as to have 1.54 g of gelatin/m2.
• various latices were added in an amount to have 1 g of a 30 % dispersion of said latex per m2.
• the various latices added to the various coating solutions were : polyethylacrylate as control, LAT1, LAT3 and LAT5.
• the point defects were in the coated backing layers were counted in 30 m2 of material and normalized to a number (#)/100 m2. It resulted that the backing layers comprising a latex with a soft (i.e.

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• 1995
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