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

Definitions

• An object of this invention is to provide a unique photographic silver halide emulsion and emulsion layer which retains the advantages of gelatin while overcoming certain disadvantages. Another object is to provide photographic emulsion layers and elements for the graphic arts industry which have improved dimensional stability. Another object is to provide photographic emulsion layers of improved dimensional stability in which the optical density of the developed image remains stable during change from a Wet to a dry state. A further object is to prepare emulsion layers and elements which can be dried more rapidly. Still other objects will be apparent from the following description of the. invention.
• the improved gelatino-silver halide emulsions of this invention comprise, in addition to the silver halide grains,
• An aqueous phase containing therein as a part of said phase (a) to 85 parts by weight of gelatin and (b) 2.5 to parts by weight of a water-soluble glycan selected from the group consisting of glycans of the empirical formulae wherein the monomeric units are naturally occurring aldoses or ketoses joined through glycosidic linkages and wherein n equals 20 to 600 and (2) 10 to parts by weight of a non-aqueous phase dispersed therein of water-dispersible colloidal particles (preferably of an average diameter of less than 400 m of a substantially water-insoluble vinyl addition polymer of an ethylenically unsaturated monomer of molecular weight less than 250.
• water-dispersible colloidal particles preferably of an average diameter of less than 400 m of a substantially water-insoluble vinyl addition polymer of an ethylenically unsaturated monomer of molecular weight less than 250.
• minor amounts usually less than 5% of the weight of the three binders, of various e
• novel tri-component colloid binder silver halide emulsions can be made. in various manners.
• light-sensitive silver halide or a mixture of such halides is precipitated in an aqueous photographic gelatin solution.
• the resulting emulsion or dispersion retains the protective colloid, and other properties of the gelatin of photographic grade.
• T o the precipitated silver halide emulsion which can be washed, ripened, etc., there are added suitable sensitizers and, if
• emulsion adjuvants and the emulsion is digested.
• an aqueous solution or dispersion of the glycan and of the water-insoluble vinyl addition polymer are added, separately or simultaneously.
• an aqueous solution or dispersion of the glycan and of the water-insoluble vinyl addition polymer are added, separately or simultaneously.
• the resulting tricomponent colloid-silver halide dispersion is coated on a suitable support, e.g., a hydrophobic film base, and the coating dried. Additional gelatin can be added along with the other two colloids to provide the required amount of gelatin in the final silver halide emulsion or dispersion.
• the light-sensitive. silver halide layer is given a sensitometric exposure through a neutral density wedge, processed by developing, fixing, etc., and the image densities are read on a conventional type of densitometer.
• the unique tricomponent gelatin/glycan/ Water-insoluble vinyl polymer silver halide emulsion yields a clear layer which is permeable to. aqueous devel-' oping and fixing solutions as is an all-gelatin layer and has comparable photosensitometric properties because of the similarity in silver halide grain structure and; size distribution. However, its physical, dimensional and practical photographic handling properties are markedly improved.
• the humidity coefiicient of expansion and size change during processing of the light-' sensitive silver halide to a silver image is markedly reduced.
• the optical density of the image in passing from the wet to the dry state is markedly stabilized so that a final dry optical density can be accurately predicted from a wet optical density reading.
• amphoteric dispersing agent preferably an amphoteric dispersing agent of the formula:
• R is an alkyl group of 12-18 carbon atoms, m is or 1, p is 2m and M is a cation selected from the group consisting of hydrogen, sodium, potassium and ammonium.
• the dispersing agent is used in an amount from 0.5% to 15.0% by weight of the waterinsoluble vinyl polymer.
• Suitable amino acid dispersing agents are disclosed in US. Patent 2,816,920, Dec. 17, 1957, and are commercially available. Two of these dispersing agents of particular interest are disodium-N-tallow-beta-iminodipropionate and the disodium N-dodecyl-beta-iminodipropionate. In the case of the former dispersing agent, tallow is a mixture of the hydrocarbon radicals oleyl, palmityl, stearyl and myristyl in order of decreasing concentration. Non-ionic as well as cationic surfactants can be used, but best results can be obtained, especially in the case of the panchromatic silver halide emulsions, by means of the amphoteric dispersing agents described above.
• the glycans used in accordance with this invention can be characterized as water-soluble condensation polymers of monosaccharides joined, through splitting off of water, to form glycosidic bonds. These include both pentose and hexose derivatives according to the following empirical equations.
• glycans While in natural glycans, "11 may vary from 10 to several thousand, the preferred glycans used in practicing the invention have from 20 to 600 such units or molecular weights-in the range from 2500100,000. Glycans of weights below the lower molecular weight range are so water diffusible they tend to wash out of the films during photographic processing, while those above 100,000 molecular weight tend to be too sparingly soluble in water, incompatible with gelatin or yield solutions of too high viscosity. Viscosities of a aqueous solution at 25 C. preferably should be below 100 centipoises.
• polysaccharides used in practicing the invention have been given the generic name glycans and most of the members are commonly known by generic names in which the -ose sulfur in the parent sugar is replaced by the suflix -an, e.g., glucan or dextran, galactan, mannan, etc., but in somecases the common names are retained, e.g., inulin.
• the glycans used according to the invention may be linear or branched, homoor heteroglycans according to the classification system in Table V, pages 22-26 of Polysaccharide Chemistry, R. L. Whistler and C. L. Smart, Academic Press, New York, (1953).
• Each repeating unit in the above empirical formulae can be considerda derivative of a naturally occurring hexose or pentose such as in which one of the hydroxyl groups reacts with the carbonyl of the same molecule to form a pyranose or furanose ring through hemiacetal formation and a glycosidic (acetal) linkage with a second hemiacetal.
• Corresponding ketals would be formed with ketoses.
• the useful polyhexoses are the water-soluble mannans, galactans, fructaus (including levans) glucofructans galactomannans, laminarins, dextrans and dextrins, etc., as well as hydrolyzed water-soluble derivatives of cellulose, starch and glycogen.
• the dextrans which are prepared commercially by bacterial action on sucrose are a particularly preferred class of glycan for this invention.
• Preferred dextrins and dextrans for this invention are described in greater detail in the assignees copending cases, Jennings, Ser. No. 776,660, filed Nov. 21, 1958, US. Patent 3,063,838, Nov. 13, 1962, and Chambers, Ser. No. 826,125, filed July 10, 1959, abandoned and in counterpart British patent specification 897,497.
• Useful glycans containing pentoses are araban and arabogalactans.
• a preferred class are the alkyl acrylates and methacrylates, e.g., polymers and copolymers of methyl, ethyl, butyl and ethylhexyl acrylate or methyl and butyl methacrylate.
• acrylic or methacrylic acid can be used in the preparation of useful copolymers. With most co-monomers, no more than 10 mole percent of such an acid is used in the polymerization with the other constitutuents so that the copolymer will remain Water-insoluble.
• vinyl monomers used to prepare water insoluble polymer and copolymer dispersions useful in accordance with this invention are the vinyl esters such as the acetate, propionate, etc., the vinyl and vinylidene halides such as vinylidene chloride; styrene and substituted styrenes; the dienes such as butadiene; acrylonitrile; alkenes such as ethylene or propylene and the like.
• the water insoluble polymers are free from color-former nuclei or groups and preferably are free from cyclic nuclei.
• acrylates in general are preferable to methacrylates and polyethylene to polyvinylidene chloride polymers and copolymers.
• the vinyl polymers in general, have an average molecular weight above 10,000.
• the particle size of vinyl dispersion is important, since the intended application requires freedom from lightscattering. In general, particle sizes below the wave length of light, i.e., below 400 m would be preferred. This may be controlled by techniques of emulsion polymerization known in the art such as the use of adequate concentrations of surfactants, the mode of stirring, the concentrations of reactants, temperature, rate of additions of monomers, etc.
• a film base support which also has adequate dimensional stability, e.g., polymethylene terephthalates, polystyrene, polycarbonates, e.g., the polycarbonate of 2,2-bis-p-hydroxyphenyl propane, polyethylene terephthalate/isphthalate, etc.
• the polyester films include those prepared from highly polymerized esters of terephthalic acid and at least one glycol of the formula HOCH WCH OH where W is a polymethylene or alkyl-substituted polymethylene of 0 to 8 carbons, e.g., 2,2-dimethylpropylene-1,-3-or a cycloalkylene radical of 5 to 6 carbon atoms, e.g., cyclopentyl-1,3, and cyclohexyl-l,4.
• W is a polymethylene or alkyl-substituted polymethylene of 0 to 8 carbons, e.g., 2,2-dimethylpropylene-1,-3-or a cycloalkylene radical of 5 to 6 carbon atoms, e.g., cyclopentyl-1,3, and cyclohexyl-l,4.
• Copolymeric films comprising up to mole percent of aliphatic dicarboxylic acids based on total moles of acids, e.g., succinic, glutaric, adipic, hexahydroterephthalic and sebacic acids, in addition to terephthalic acid, are also useful.
• These supports may have various anchor layers, e.g., layers of vinylidene chloride copolymers as disclosed in US. Patent 2,779,684.
• the above-described polymers or copolymers may contain a number, e.g., 1 to 12 or more, of ether groups in the polymer chain.
• ether groups may be added as part of ether containing glycol derivatives or formed by side reactions during polymerization.
• the photographic emulsions may be coated on various films, foils and plates made of glass, metal, e.g., aluminum, various waterproof papers, cellulose derivatives, e.g., cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate-butyrate, and cellulose nitrate; other superpolymers, e.g., nylon, polyvinyl chloride, poly(vinyl chloride covinyl acetate), etc.
• the polymeric dispersions used in a preferred embodiment of this invention are prepared in a conventional manner, starting with a polymerizable liquid monomer.
• This monomer is emulsified with water by means of the dispersing agents described above, and subjected to a conventional emulsion polymerization using a free radical initiator, e.g. peroxide or a,oc'aZO bis-(isobutyronitrile).
• a free radical initiator e.g. peroxide or a,oc'aZO bis-(isobutyronitrile).
• a free radical initiator e.g. peroxide or a,oc'aZO bis-(isobutyronitrile
• Procedure A there is given a description of the preparation of a particularly preferred dispersion, that of polyethylacrylate.
• a bulk polymerization and prepare the dispersions by dispersing the molten polymer in water in the presence of a dispersing agent, such
• a -inch strip of a coating is scribed with a stylus so as to produce, near each end of the strip, fiducial marks which will be in close proximity to the fiducial marks of a calibrated Invar plate when the strip and Invar plate are brought into contact with one another.
• the strip is then conditioned for 24 hours at a constant temperature and humidity and then, while maintained at the same conditions, placed in flat contact with the Invar plate.
• Two Gaertner filar micrometer microscopes having a total magnification of 100 diameters and micrometer least count 2x10 inches, are mounted so that measurements may be obtained by means of a graduated glass scale of distances between the fiducial marks on the coating strips and the corresponding fiducial marks on the Invar plate.
• the Invar plate, microscope and coating -strip are all housed in a conditioning cabinet equipped with arm ports and viewing Windows.
• the distance is determined between the two fiducial marks on the strip at a known humidity.
• the process is repeated, with 24- hour preconditioning, to determine the distance between the strips two fiducial marks at another known humidity.
• Invar is a nickel-steel altloy.
• Dimensional stability in ter-ms of processing size change is determined in a very similar manner. Distance between fiducial marks is determined on a coating strip which has been conditioned under constant temperature and humidity for 24 hours. The strip is then conventionally processed and dried, conditioned at the previous constant temperature and humidity vfor 24 hours, and measured to determine the change in distance between fiducial marks. The processing size change is calculated by dividing this change in distance by the average distance.
• Density stability was deter-mined from measurements of diffuse transmission densities (American Standards Association, Standard Z3-8.2.5-1946). The density measurements were made on both wet and dry films and on films during the process of drying at various Wet lbulb temperatures of the drying air.
• Dry adhesion of emulsion to the support was measured by the common test wherein cross-hatched lines are cut through the emulsion and a piece of pressure-sensitive tape is applied to an emulsion surface and then rapidly pulled off. Removal of a .part of the emulsion from the base indicates inferior anchorage. Wet anchorage can be determined similarly after normal photographic processing, by determining the tendency of the wet emulsion to lift oi the base when a force is applied tangentially at the edge of the cross hatched lines.
• Curl was measured by determining the weight required to restore a 10" x 12" sheet of film conditioned at 20% RH and F. to a flat condition.
• PROCELURE B A 22-liter fluted pot was equipped as described in Procedure A and purged with nitrogen in the same manner. T o the pot were added 8 liters of distilled water and 16.7 g. of a high molecular weight polyacrylamide (thermal stabilizer) which was added slowly through a long stem funnel of narrow bore and washed in with 2.5 liters of distilled Water. The mixture was stirred for 2 to 3 hours at room temperature to effect solution. To the solution of polyacrylamide in the pot were added 667 g. of a 30% by weight aqueous isopropanol solution of a surfactant of the formula which was washed in with 400 ml. of distilled Water.
• a high molecular weight polyacrylamide thermo stabilizer
• a two stage polymerization was carried out as described in Procedure A except that butyl acrylate was used in place of ethyl acrylate.
• the composition by weight of the dispersion made by this procedure is 30% polybutyl acrylate and 1.2% polyether sulfate surfactant.
• PROCEDURE C Procedure B was essentially repeated except that 800 g. of a 25% by weight aqueous solution of Tamol 371 (registered trade name, Rohm and Haas, defined by Haynes, Chemical Trade Names and Commercial Synonyms, 2nd edition, 1955, Van Nostrand and Co., New York, as the sodium salt of a carboxylated polyelectrolyte) which was washed in with 267 ml. of distilled water was used in place of the sodium salt of a polyether sulfate surfactant.
• a two-stage polymerization was carried out as described in Procedure A except that methyl methacrylate was used in place of ethyl acrylate.
• the composition by weight of the dispersion made by this procedure is polymethyl methacrylate and 1.2% sodium salt of a carboxylated polyelectrolyte.
• PROCEDURE D Procedure A was essentially repeated except that 716 g. of a 28% by weight aqueous solution of a surfactant of the formula which was washed in with 714 ml. of distilled water, was used in place of disodium-N-tallow-,G-iminodipropionate.
• a mixture of monomers consisting of 3500 g. of
• Example I A high contrast silver iodobromide emulsion was prepared by combining solutions of silver nitrate, ammonium bromide and potassium iodide in a conventional manner using 14.7 g. of gelatin as a protective colloid per mole of silver halide. The emulsion was divided into two parts, A and B, and freed of unwanted soluble salts by conventional photographic washing procedures. Each emulsion was digested in the presence of the usual chemical sensitizers and carbocyanine dyes to give them panchromatic sensitivity. At the end of digestion, there was added to emulsion A, 191 g.
• the backing binder which was equal to mg./dm. consisted of gelatin for film A and consisted of one part of gelatin to two parts of dispersed polyethyl acrylate for film B.
• a third film, film C was a commercially available all-gelatin film with characteristics similar to film A and was used as a second control.
• a conventional, square-root-of-two stepwedge was used to expose all 3 films in a standard sensitometer. The films were then developed in a conventional metol-hydroquinone developer, fixed in a Na S O hardening fixer and washed.
• the diffuse transmission densities (American Standards Association, Standard Z38.2.5-1946) were measured on the wet film and this measurement was repeated on the dry film. This determination was obtained from the average values of four duplicate sets for each film to insure representative measurements. These were then evaluated as a function of the wet bulb temperature of the drying air, i.e. the film temperature during drying was varied from 70 to F. in 10 F. increments. The density changes expressed in percent of wet density for these 3 films are listed in Table I.
• the data illustrate the small (and nearly constant) density changes of film B, containing the modified binder of this invention, as opposed to the conventional films with all-gelatin binders, A and C.
• the latter exhibit an abrupt change from to at a critical temperature which is characteristic for films with conventional gelatin binders.
• Table IV also shows that the humidity coefficient of expansion between 30 and 80% RH at 70 F. of film B (containing dextran and a polyethyl acrylate dispersion) i was much lower than of the all gelatin films A and C..
• Example II Example II was repeated in all respects except that the silver halide precipitation was carried out in the manner used in the art to produce a low contrast emulsion. As in Example I, the emulsion was divided into two parts,
• Example I Evaluation of these films, as in Example I, showed that the density stability of film E from the wet-to-dry state was much greater than that of the control film D. Similarly the dimensional stability, impact strength and drying rate of film E were superior to film D.
• Example III Films of Example I were further tested. Each film was exposed and processed and the optical densities read while wet in the vicinity of 1.0 and 2.0 foreach film in the manner shown in Example I. Each film was allowed to dry in a room conditioned as follows:
• Example V two fiducial marks at the ends of a A" x 10" film strip using a pair of microscopes fitted with filar micrometers. The results are shown in Table IV below.
• film B shows much less fluctuation 1n dens1ty 2 from the wet to dry state than film A, either on the first drying or on subsequent rewetting and drying. Further, film B dries much more rapidly than film A.
• Example VI A panchromatically sensitized, silver iodobromide emulsion was prepared similarly to that in Example 1 except that the silver halide precipitation was carried out in the manner used in the art to produce a medium contrast emulsion. At the end of digestion sufficient gelatin was added tothe emulsion to bring the total concentration of gelatin to 133 g. per mole of silver halide. After removing a portion of the emulsion to serve as an all-gelatin control, 223 g. per mole of silver halide of a 30% by weight colloidal dispersion of polyethyl acrylate (prepared as in Procedure A) was added to the remainder of the emulsion, this being equivalent to 67 g.
• Example IV the films were evaluated as in Example IV. Cunl and impact resistance were determined as described earlier in the specification. It can be seen that the modified binder causes. an increase in speed and contrast, improved wet-to-dry density stability and improved curl and impact resistance. It is also noted that, with the various polysaccharides used, there was a difference in the concentration required for optimum density stability. In the case of araban, density stability is improved with increasing concentration and the results indicate that still higher concentrations would be needed to achieve the stability of the better glycans (polysaccharides)
• Example VII Example VI was repeated through the steps of adding Example VIII
• Example VI was repeated through the steps of adding gelatin up to a concentration of 133 g.
• No'rE The dextran used in this example and in Example VII was the same as that in Example 1.
• auxiliary layers may be employed such as antiabrasion layers and antihalation backing or undercoat layers.
• the emulsions may be modified by the addition of general emulsion sensitizers, e.g., alkyl thiourea, phenyl iso-,
• thiocyanate sodium thiosulfate and alkyl isothiocyanate
• metal compounds e.g., of gold, platinum palladium, iridium, rhodium, mercury, cadmium etc.
• antifogging agents e.g., Z-mercaptotetrazole, benzotriazole, triazindene, tetra zindene and S-nitrobenzimidazole
• sensitizing dyes color formers, the polyoxyalkylene ethers, polyglycols, and amines disclosed in US.
• Patents 2,400,532, 2,423,549 and 1,925,508 ; hardeners, e.g., formaldehyde and other aliphatic aldehydes, dimethylol urea, trirnethylol melamine; chrome alum and other chromium compounds; coating aids, image color modifiers, brightening agents, colorants, e.g., pigments, matting agents and other emulsion adjuvants.
• hardeners e.g., formaldehyde and other aliphatic aldehydes, dimethylol urea, trirnethylol melamine
• chrome alum and other chromium compounds chrome alum and other chromium compounds
• coating aids image color modifiers, brightening agents, colorants, e.g., pigments, matting agents and other emulsion adjuvants.
• Photographic requirements of graphic arts emulsions are often best met by silver halides in which the predominant halide is bromide. Up to 10. mole percent iodide is added to vary the photographic behavior as well as the usual chemical sensitizers and optical sensitizing dyes.
• the unique binder advantages of this invention such as improvements in wet-to-dry density stability, impact resistance, dimensional stability, anchorage to the support, flatness and drying rate are also applicable in varying degrees to other halides over a wide range of compositions including silver chloride, chloro-bromide and iodochloro-bromide emulsions.
• This invention has the advantage of providing superior photographic emulsions for the manufacture of films having improved physical properties and improved wetto-dry optical density stability of the developed image.
• Films made according to the present invention do not sufier the disadvantage of loss of optical density of the developed image during drying of the film.
• improved physical properties dimensional stability is particularly significant but improved flexibility and improved anchorage are also important.
• amphoteric dispersing agents used in the panchromatic emulsions in contrast to the anionic and cationic surfactants used in previously disclosed products, do not interfere with dye sensitization.
• a further advantage is the simplicity of the process of this invention; since the additions are in the form of aqueous solutions and dispersions, the process can be carried out simply and economically on a commercial scale with no need for elaborate equipment such as solvent recovery systems.
• Polymers are often incompatible and, therefore, mixtures of two or three polymers cause difiiculties where clarity is desired, as in photographic films. There are no reliable rules known in polymer science for predicting when compatibility will occur or What balance of properties the final polymer mixture will have. According to the present invention, however, applicants have provided a mixture of three different polymers and have found them to be compatible and to give photographic emulsions having excellent optical clarity as well as other useful photographic and physical properties. In the emulsions, in general the sum of the light absorbed and scat- 'tered by the combination of the three polymeric binder components in the absence of the silver and silver salts correspond to an optical density of not more than 0.1, which is advantageous.
• a gelatino-silver halide emulsion comprising, in addition to the silver halide grains,
• an aqueous phase containing as a part thereof (a) 20 to parts by weight of gelatin and (b) 2.5 to 40 parts by weight of a water-soluble glycan selected from the group consisting of glycans of the empirical formulae where the monomeric units are naturally occurring units selected from the group consisting of aldose and ketose units and wherein n is 20 to 600, and
• R is an alkyl group of 12-18 carbon atoms
• m is one of the numbers 0 and 1
• p is 2m
• M is a cation selected from the group consisting of hydrogen, sodium, potassium and ammonium.
• a photographic element comprising a support hearing at least One layer of a photographic emulsion as defined in claim 1.
• particles of addition polymer in the emulsion have an average diameter less than 400 mp. and an average molecular weight of at least 10,000.
• R is an alkyl group of 12-18 carbon atoms
• m is one of the numbers 0 and 1
• p is 2-m
• M is a cation selected from the group consisting of hydrogen, sodium, potassium and ammonium.

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• 1962
  • 1962-02-27 US US176140A patent/US3203804A/en not_active Expired - Lifetime
  • 1962-07-06 GB GB26073/62A patent/GB976221A/en not_active Expired
  • 1962-07-09 DE DEP29782A patent/DE1158365B/de active Pending
  • 1962-07-09 FR FR903376A patent/FR1335161A/fr not_active Expired
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