US3062648A - Photographically sensitive lithographic printing plate - Google Patents

Photographically sensitive lithographic printing plate Download PDF

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US3062648A
US3062648A US7712A US771260A US3062648A US 3062648 A US3062648 A US 3062648A US 7712 A US7712 A US 7712A US 771260 A US771260 A US 771260A US 3062648 A US3062648 A US 3062648A
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emulsion
lithographic printing
colloidal silica
printing plate
gelatin
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Irvin H Crawford
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Eastman Kodak Co
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/06—Silver salts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
    • B41N3/00—Preparing for use and conserving printing surfaces
    • B41N3/03—Chemical or electrical pretreatment
    • B41N3/036—Chemical or electrical pretreatment characterised by the presence of a polymeric hydrophilic coating

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  • This invention relates to lithographic printing plates and to methods of making those plates, especially paper printing plates.
  • the invention relates to both the preparation of the lithographic plate and the preparation of a hydrophilic lithographic surface on a paper support requiring no insolubilizing agent.
  • One object of my invention is to prepare printing plates of the negative working type that is used to make positive copies from negative originals. Another object of my invention is to prepare sensitized lithographic printing plate having an emulsion thereon which upon exposure and development forms a water repellent oleophilic image thereon. Another object of my invention is to provide lithographic printing plates in which the hydrophilic surface employed comprises colloidal silica and a small amount of a resin binder therefor. A further object of my object of my invention is to combine a lithographic coating mixture with a paper base which is sufiiciently impervious to the action of Water to substantially resist stretching and shrinking. Other objects of my invention will appear herein.
  • Insolubilizing agents which have been employed are formaldehyde, glutaraldehyde, ureaformaldehyde resin, melamine-formaldehyde resin, or the salt of a bior tri-valent metallic ion such as of copper, iron, aluminum and chromium.
  • the lithographic printing plate which is the object of this invention is made by applying to the surface of a Water-resistant support, such as paper which has been made water-resistant such as by applying a resinous coating thereto, a hydrophilic layer essentially consisting of colloidal silica and methyl methacrylate resin emulsion. Over this hydrophilic layer is then applied a layer of an unhardened silver halide emulsion of the type described in U.S. Patent No. 2,675,313 of Yutzy and Yackel.
  • the printing plate in accordance with my invention is characterized by the complete absence of insolubilizing agents therein which would cause hardening of the gelatin of the silver halide emulsion prior to actual exposure and development thereof.
  • the silver halide emulsion used contains therein a tanning developer which upon development of the emulsion in aqueous alkaline solution after exposure causes hardening or tanning of the gelatin of the emulsion only in the specific areas where the silver is reduced. This leaves a positive image of reduced silver and hardened gelatin while the remaining areas of the silver halide emulsion are soft and unhardened.
  • the unhardened emulsion is thereupon removed such as by washing with warm water (90-110" F.) revealing the hydrophilic surface underneath but leaving the oleophilic 3,662,648 Patented Nov. 6, H952 image on the hydrophilic surface to make a satisfactory lithographic printing plate.
  • the supports as described in the prior art which involve the use of insolubilizing agents in their preparation would be unsuitable, as those agents not only insolubilize the hydrophilic adhesive material used in the coating, but also have a hardening effect upon the unhardened gelatin emulsion which is applied thereover.
  • the hydrophilic layer in accordance with the present invention does not require insolubilizing agent to give abrasion resistance on the press and thus constitutes an improvement over previous hydrophilic layers.
  • FIG. 1 the figure illustrates a lithographic printing plate in accordance with my invention in which a paper base is coated with a hydrophilic layer of colloidal silica and methyl methacrylate polymer and thereover is applied an unhardened gelatino-silver halide emulsion containing tanning developer.
  • the hydrophilic layer employed in accordance with my invention essentially consists of a colloidal silica dispersion and a polymethyl methacrylate emulsion.
  • a colloidal silica dispersion such as would be useful in my invention is described in U.S. Patent 2,375,738 of John F. White.
  • Colloidal silica dispersions useful in preparing hydrophilic layers in accordance with my invention are sold as aqueous silica dispersions under the trade names of Syton 200 (solids content on the order of 30%) by the Monsanto Chemical Company, Merrimac Division, Everett, Massachusetts, and Ludox (aqueous colloidal solution of hydrated silica containing 30% SiO by the Du Pont Company.
  • the silica concentration of the colloidal silica dispersion used can vary such as from 1040% or more.
  • the polymethyl methacrylate in the coating composition employed for forming the hydrophilic layer is supplied in the form of an emulsion thereof such as obtained by the emulsion polymerization of methyl methacrylate as is known in the art.
  • a methyl methacrylate resin emulsion which has been used successfully in coating compositions for the application of hydrophilic layers in accordance with my invention is sold under the trade name Rhoplex AC33 by Rohm and Haas Company. It is ordinarily preferred that pigment or filler be incorporated in the composition which supplies the hydrophilic layer. Materials such as finely divided clay, titanium dioxide, barium sulfate, or the like, alone or in admixture have been found to be useful in this connection.
  • the colloidal silica should constitute at least 30% of the silica-pigment (filler) mixture employed in preparing the hydrophilic layer composition. In some cases it might be desirable to add a thickener to the composition. Hydroxyethyl cellulose is useful for this purpose. Instead of or in addition to the pigments and fillers listed, materials which might be employed are finely divided glass, sand, quartz or diatomaceous earth. In some cases it might be desirable to add a pigment or dye to give a colored coating which may improve resolution and decrease halation.
  • the pigment and/or filler and the colloidal silica should have a ratio to acrylate resin 6:1 to 8:1 dry basis.
  • the composition thus prepared may have a solids content of from 30 up to 50%, although compositions having solids contents outside of this range may be found to be useful.
  • the conditions should be such that a cov erage of the hydrophilic layer dry Weight is on the order of 18-30 grams per square meter.
  • the emulsion layer is supplied by a composition of an unhardened gelatino-silver halide photographic emulsion such as described in US. Patent No. 2,675,313, which emulsion contains a small proportion of a tanning development agent.
  • Some tanning developers which are useful in the emulsion composition are various dihydroxy diphenyls, 5,6,7,8-tetrahydronaphtho hydroquinone, hydroquinone or pyrocatechol.
  • the emulsion layer should not be harder than would be in the case with gelatin containing 0.25 ounce of formalin (diluted 1:3 with Water) or 0.7 gram of dry formeldehyde per pound when freshly coated or 0.1 ounce of formalin diluted 1:3 with water per pound for a sample aged 3-6 months.
  • unhardened and substantially unhardened as used herein, it is to be understood that this means a hardness of the order obtained from gelatin treated with no more formaldehyde than listed above.
  • the support for the layers which make up my invention is paper and it is preferred that paper made waterresistant to give good dimensional stability and resistance to stretching and pulling be used.
  • This can be conveniently done by coating formaldehyde-free paper on both sides with a solution consisting of 4% casein and 96% styrene-butadiene copolymer latex in water to which ammonium hydroxide has been added to adjust the pH to the alkaline side and a Wetting agent such as sodium lauryl sulfate has been used to facilitate the application of the coating to the paper, the solution for producing water resistance containing 30% of solids and the dry coverage of the coating on the paper being on the order of grams of coating per square meter of surface.
  • the lithographic paper prepared in accordance with my invention is particularly useful in making positives from negative originals such as for the making of printing plates from microfilm records.
  • the emulsion layer may be exposed to light through a film negative or to an opaque negative by reflected light.
  • the exposed emulsion is then activated in an aqueous alkali solution such as a 4% solution of sodium carbonate in water, which solution may contain 10% of urea and 0.1% of potassium bromide or some other desensitizer.
  • a desensitizer is that the finishing of the processing might be carried out in ordinary light although the use of subdued light might, in many cases, be preferable.
  • the silver in the area of the emulsion which had been exposed is developed by the developer in the emulsion and as the development proceeds the gelatin is also hardened or insolubilized, but only in the specific areas where the silver is reduced. This leaves a positive image of reduced silver and hardened gelatin, all the remaining areas thereof being soft and unhardened.
  • the unhardened gelatin is removed and an oleophilic image is formed on the hydrophilic surface making a satisfactory lithographic printing plate.
  • the plate thus formed is then suitable for use in a printing process in which the plate is first wet with an aqueous fountain solution, the liquid being held by the hydrophilic surface and repelled by the oleophilic image. Next the plate is contacted by inking rollers the greasy ink adhering to the oleophilic image but being repelled by the moistened hydrophilic areas. Thus, an ink image is formed, which is transferred to a rubber blanket roller from which the image is transferred to a paper sheet.
  • Example 1 A composition was prepared comprising clay 90 parts, 312 parts of an aqueous colloidal solution of hydrated silica containing SiO and a small amount of alkali as a stabilizing agent, and polymethyl methacrylate resin emulsion 65 parts.
  • the clay and colloidal silica were mixed and passed through a suitable colloid mill or homogenizer to disperse the pigment.
  • the polymethyl methacrylate emulsion was then added and the mass was mixed with slow agitation to prevent the entrapment of air, all at room temperature.
  • the ratio of pigment (clay and colloidal silica) to binder (acrylate resin) is 6 to 1, dry basis.
  • the total solids content is 44.6%, the remainder being water.
  • the completed formula was coated on paper, stable in Water, at the dry coverage rate of l8-30 grams of hydrophilic layer per square meter.
  • the coating was dried in a current of Warm, dry air and was then heated to a temperature of 240 to 270 F. by radiant heaters or other heating device.
  • the heat treatment causes the acrylic resin to coalesce and form a continuous film thereby holding the clay and SiO particles in place and thus providing adequate Wet abrasion resistance.
  • the thus coated paper was overcoated with a hardened gelatin-silver halide photosensitive emulsion of the type described in US. Patent 2,675,313 in the form of a layer of .005 inch thickness.
  • the product thus prepared was useful for preparing lithographic printing plates as described above.
  • Example 2 The preceding was repeated except that the composition employed for the hydrophilic layer consisted for water dispersible titanium dioxide 90 parts, colloidal silica dispersion (30% Si0 312 parts, and polymethyl methacrylate emulsion parts. The ratio of Ti0 and silica to resin was approximately 6:1 dry weight. A product having properties useful for lithographic purposes was obtained.
  • Example 3 A composition for applying the hydrophilic layer to paper as described in the preceding examples was prepared by adding the polymethyl methacrylate emulsion directly to the dispersion of colloidal silica, in the proportion of 400 parts of silica dispersion and 43 parts of polyalkyl acrylate emulsion. As a result the mixture had a low viscosity. Hydroxyethyl cellulose was added thereto as a thickener. The composition thus obtained was coated out onto paper having good stability in water, which was then overcoated with unhardened silver halide emulsion as described herein. A product useful for preparing lithographic printing plates was obtained.
  • Example 5 The above was repeated except that the composition used for the hydrophilic layer consisted of clay 50 parts, titanium dioxide 50 parts, colloidal silica dispersion 30% SiO 835 parts, polyalkyl acrylate emulsion 109 parts, and hydroxyethyl cellulose (4% solution) 160 parts.
  • the hydrophilic coating as described herein functions in the following manner, but it is to be understood that the invention is not limited to the conclusions of the theoretical discussion. It is believed that the acrylic resin which is present in the hydrophilic layer as a continuous film is hydrophobic or water repellent and that it does not dissolve, swell or take up water on its surface when contacted with the fountain solutions in printing, but that it provides a tough abrasion resistant film to bind the pigment particles firmly in place. For this purpose some other resin of an alkyl ester of an acrylic acid or methacrylic acid or a styrenebutadiene or styrene-acrylic resin latex would be useful.
  • the colloidal silica has a very small particle size, the particles being on the order of 15 millimicrons or even less in diameter. Therefore, a large surface area is presented as these particles are in discreet or separated form.
  • the coating containing the colloidal silica has dried the silica becomes resistant to re-dispersing but the colloidal silica particles not completely covered with binder present a large surface area available for adsorption of moisture. It is believed that these fine silica particles adsorb moisture tenaciously, thus presenting a uniform ink repellent film of water to the press inking rollers.
  • the binder When the pigment to binder ratio is too low the binder completely encompasses the SiO particles; hence, moisture is not adsorbed. With this condition complete inking of the entire plate surface occurs.
  • the pigment to binder ratio is between approximately 6:1 and 8:1 as specified herein, the binder spot welds the silica particles together leaving a surface of those particles free to adsorb moisture.
  • the pigment to binder ratio is much above 8:1 insufficient binder is present to bind the particles of silica and other pigment is place and the coating has a tendency to disintegrate in the printing operation.
  • a lithographic printing plate substantially free of gelatin hardener, containing in that order 1) a water resistant support, (2) a hydrophilic layer comprising an inorganic component of colloidal silica and pigment-filler, the silica constituting at least 30% thereof dry weight, and a water resistant latex resin component, the ratio of the inorganic component to the resin component being approximately 6:1, dry weight, and (3) a layer of a gelatino-silver halide emulsion containing therein a gelatin tanning silver halide developing agent.
  • a lithographic printing plate substantially free of gelatin hardener, containing in that order a water resistant paper base, a hydrophilic layer of a mixture of titanium dioxide, clay and colloidal silica, the latter constituting at least 30% of the mixture, and a methyl methacrylate latex resin component, the ratio of the mixture of clay, titanium dioxide and colloidal silica to latex resin being within the range of approximately 6:1 to approximately 8:1, dry weight, and a layer of a gelatinosilver halide emulsion containing a tanning developer.
  • a lithographic printing plate substantially free of gelatin hardener, containing in that order (1) a water resistant paper base support, (2) a hydrophilic layer comprising an inorganic component of colloidal silica and pigment-filler, the silica constituting at least 30% thereof dry weight, and a water resistant latex resin component, the ratio of the inorganic component to the resin component being within the range of approximately 6:1 to approximately 821, dry weight, and (3) a layer of a gelatino-silver halide emulsion containing therein a gelatin tanning silver halide developing agent.
  • a lithographic printing plate substantially free of gelatin hardener, containing in that order (1) a water resistant support, (2) a hydrophilic layer comprising an inorganic component of colloidal silica and pigment-filler, the silica constituting at least 30% thereof dry weight, and a water resistant methyl methacrylate latex resin component, the ratio of the inorganic component to the resin component being within the range of approximately 6:1 to approximately 8:1, dry weight, and (3) a layer of a gelatino-silver halide emulsion containing therein a gelatin tanning silver halide developing agent.
  • a lithographic printing plate substantially free of gelatin hardener, containing in that order a water resistant paper base support, a hydrophilic layer of a mixture of clay and colloidal silica, the silica constituting at least 30% thereof and a methyl methacrylate latex resin component, the ratio of the clay and colloidal silica to the latex resin component being within the range of approximately 6:1 to approximately 8:1, dry weight, and a layer of a gelatino-silver halide emulsion containing a tanning developer.
  • a lithographic printing plate substantially free of gelatin hardener, containing in that order a water resistant paper base support, a hydrophilic layer of a mixture of titanium dioxide and colloidal silica, the latter being at least 30% thereof, and a methyl methacrylate latex resin component, the ratio of TiO and colloidal silica to the latex resin component being within the range of approximately 6:1 to approximately 8:1, dry weight, and a layer of a gelatino-silver halide emulsion containing a tanning developer.

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Description

Nov. 6, 1962 l. H. CRAWFORD 3,062,648
PHOTOGRAPHICALLY SENSITIVE LITHOGRAPHIC PRINTING PLATE Filed Feb. 9, 1960 U/VHAROENEO OELATl/VO-S/LVER HAL/DE EMULSION OO/V7Al/Vl/V6 7AN/V/IV6 DEVELOPER HYDROPH/L/C LAYER OF OOLLO/OAL SILICA A/VO METHYL ME 7' l-IACRYLATE POLYMER "Ill/ll IA mm //////////Zi PAPER BASE ATTORNEYS United States Patent O 3,062,648 PHOTOGRAPHECALLY SENSETIVE LKTHO- GRAPHIC PREN'HNG PLATE Irvin H. Crawford, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Feb. 9, 195%, Ser. No. 7,712 6 Claims. (Cl. 96-76) This invention relates to lithographic printing plates and to methods of making those plates, especially paper printing plates. The invention relates to both the preparation of the lithographic plate and the preparation of a hydrophilic lithographic surface on a paper support requiring no insolubilizing agent.
One object of my invention is to prepare printing plates of the negative working type that is used to make positive copies from negative originals. Another object of my invention is to prepare sensitized lithographic printing plate having an emulsion thereon which upon exposure and development forms a water repellent oleophilic image thereon. Another object of my invention is to provide lithographic printing plates in which the hydrophilic surface employed comprises colloidal silica and a small amount of a resin binder therefor. A further object of my object of my invention is to combine a lithographic coating mixture with a paper base which is sufiiciently impervious to the action of Water to substantially resist stretching and shrinking. Other objects of my invention will appear herein.
The providing of a satisfactory hydrophilic surface on a support for use for lithographic printing plates has been the subject of many patents. The majority of these patents use water absorptive materials such as polyvinyl alcohol, casein, gelatin, carboxymethyl cellulose, starch, or the like, as the continuous phase of the hydrophilic layer. Ordinarily, some pigment or filler such as titanium dioxide, clay, or blanc fixe is added to provide a suitable surface texture. The continuous phase is insolubilized in some way to prevent disintegration of the layer when wet under the stresses and abrasive forces of the printing press. Insolubilizing agents which have been employed are formaldehyde, glutaraldehyde, ureaformaldehyde resin, melamine-formaldehyde resin, or the salt of a bior tri-valent metallic ion such as of copper, iron, aluminum and chromium.
The lithographic printing plate which is the object of this invention is made by applying to the surface of a Water-resistant support, such as paper which has been made water-resistant such as by applying a resinous coating thereto, a hydrophilic layer essentially consisting of colloidal silica and methyl methacrylate resin emulsion. Over this hydrophilic layer is then applied a layer of an unhardened silver halide emulsion of the type described in U.S. Patent No. 2,675,313 of Yutzy and Yackel. The printing plate in accordance with my invention is characterized by the complete absence of insolubilizing agents therein which would cause hardening of the gelatin of the silver halide emulsion prior to actual exposure and development thereof. The silver halide emulsion used contains therein a tanning developer which upon development of the emulsion in aqueous alkaline solution after exposure causes hardening or tanning of the gelatin of the emulsion only in the specific areas where the silver is reduced. This leaves a positive image of reduced silver and hardened gelatin while the remaining areas of the silver halide emulsion are soft and unhardened. The unhardened emulsion is thereupon removed such as by washing with warm water (90-110" F.) revealing the hydrophilic surface underneath but leaving the oleophilic 3,662,648 Patented Nov. 6, H952 image on the hydrophilic surface to make a satisfactory lithographic printing plate.
Since the system depends upon absence of hardening of the emulsion in the non-exposed areas there should be nothing in the base which will harden or promote hardening of the emulsion. Thus, the supports as described in the prior art which involve the use of insolubilizing agents in their preparation would be unsuitable, as those agents not only insolubilize the hydrophilic adhesive material used in the coating, but also have a hardening effect upon the unhardened gelatin emulsion which is applied thereover. The hydrophilic layer in accordance with the present invention does not require insolubilizing agent to give abrasion resistance on the press and thus constitutes an improvement over previous hydrophilic layers.
Referring to the attached drawing the figure illustrates a lithographic printing plate in accordance with my invention in which a paper base is coated with a hydrophilic layer of colloidal silica and methyl methacrylate polymer and thereover is applied an unhardened gelatino-silver halide emulsion containing tanning developer.
The hydrophilic layer employed in accordance with my invention essentially consists of a colloidal silica dispersion and a polymethyl methacrylate emulsion. The making of a colloidal silica dispersion such as would be useful in my invention is described in U.S. Patent 2,375,738 of John F. White. Colloidal silica dispersions useful in preparing hydrophilic layers in accordance with my invention are sold as aqueous silica dispersions under the trade names of Syton 200 (solids content on the order of 30%) by the Monsanto Chemical Company, Merrimac Division, Everett, Massachusetts, and Ludox (aqueous colloidal solution of hydrated silica containing 30% SiO by the Du Pont Company. The silica concentration of the colloidal silica dispersion used can vary such as from 1040% or more.
The polymethyl methacrylate in the coating composition employed for forming the hydrophilic layer is supplied in the form of an emulsion thereof such as obtained by the emulsion polymerization of methyl methacrylate as is known in the art. A methyl methacrylate resin emulsion which has been used successfully in coating compositions for the application of hydrophilic layers in accordance with my invention is sold under the trade name Rhoplex AC33 by Rohm and Haas Company. It is ordinarily preferred that pigment or filler be incorporated in the composition which supplies the hydrophilic layer. Materials such as finely divided clay, titanium dioxide, barium sulfate, or the like, alone or in admixture have been found to be useful in this connection. The colloidal silica should constitute at least 30% of the silica-pigment (filler) mixture employed in preparing the hydrophilic layer composition. In some cases it might be desirable to add a thickener to the composition. Hydroxyethyl cellulose is useful for this purpose. Instead of or in addition to the pigments and fillers listed, materials which might be employed are finely divided glass, sand, quartz or diatomaceous earth. In some cases it might be desirable to add a pigment or dye to give a colored coating which may improve resolution and decrease halation.
ln compounding the materials to form a coating com position the pigment and/or filler and the colloidal silica should have a ratio to acrylate resin 6:1 to 8:1 dry basis. The composition thus prepared may have a solids content of from 30 up to 50%, although compositions having solids contents outside of this range may be found to be useful. The conditions should be such that a cov erage of the hydrophilic layer dry Weight is on the order of 18-30 grams per square meter.
smas es The emulsion layer is supplied by a composition of an unhardened gelatino-silver halide photographic emulsion such as described in US. Patent No. 2,675,313, which emulsion contains a small proportion of a tanning development agent. Some tanning developers which are useful in the emulsion composition are various dihydroxy diphenyls, 5,6,7,8-tetrahydronaphtho hydroquinone, hydroquinone or pyrocatechol. For the successful operation of the invention the emulsion layer should not be harder than would be in the case with gelatin containing 0.25 ounce of formalin (diluted 1:3 with Water) or 0.7 gram of dry formeldehyde per pound when freshly coated or 0.1 ounce of formalin diluted 1:3 with water per pound for a sample aged 3-6 months. By unhardened and substantially unhardened as used herein, it is to be understood that this means a hardness of the order obtained from gelatin treated with no more formaldehyde than listed above.
The support for the layers which make up my invention is paper and it is preferred that paper made waterresistant to give good dimensional stability and resistance to stretching and pulling be used. This can be conveniently done by coating formaldehyde-free paper on both sides with a solution consisting of 4% casein and 96% styrene-butadiene copolymer latex in water to which ammonium hydroxide has been added to adjust the pH to the alkaline side and a Wetting agent such as sodium lauryl sulfate has been used to facilitate the application of the coating to the paper, the solution for producing water resistance containing 30% of solids and the dry coverage of the coating on the paper being on the order of grams of coating per square meter of surface.
The lithographic paper prepared in accordance with my invention is particularly useful in making positives from negative originals such as for the making of printing plates from microfilm records.
For instance, the emulsion layer may be exposed to light through a film negative or to an opaque negative by reflected light. The exposed emulsion is then activated in an aqueous alkali solution such as a 4% solution of sodium carbonate in water, which solution may contain 10% of urea and 0.1% of potassium bromide or some other desensitizer. The advantage of using a desensitizer is that the finishing of the processing might be carried out in ordinary light although the use of subdued light might, in many cases, be preferable. During activation of the emulsion the silver in the area of the emulsion which had been exposed is developed by the developer in the emulsion and as the development proceeds the gelatin is also hardened or insolubilized, but only in the specific areas where the silver is reduced. This leaves a positive image of reduced silver and hardened gelatin, all the remaining areas thereof being soft and unhardened. By washing with warm water or some other suitable technique the unhardened gelatin is removed and an oleophilic image is formed on the hydrophilic surface making a satisfactory lithographic printing plate.
The plate thus formed is then suitable for use in a printing process in which the plate is first wet with an aqueous fountain solution, the liquid being held by the hydrophilic surface and repelled by the oleophilic image. Next the plate is contacted by inking rollers the greasy ink adhering to the oleophilic image but being repelled by the moistened hydrophilic areas. Thus, an ink image is formed, which is transferred to a rubber blanket roller from which the image is transferred to a paper sheet.
The following examples illustrate my invention:
Example 1 A composition was prepared comprising clay 90 parts, 312 parts of an aqueous colloidal solution of hydrated silica containing SiO and a small amount of alkali as a stabilizing agent, and polymethyl methacrylate resin emulsion 65 parts. In forming a coating composition therefrom, the clay and colloidal silica were mixed and passed through a suitable colloid mill or homogenizer to disperse the pigment. The polymethyl methacrylate emulsion was then added and the mass was mixed with slow agitation to prevent the entrapment of air, all at room temperature. The ratio of pigment (clay and colloidal silica) to binder (acrylate resin) is 6 to 1, dry basis. The total solids content is 44.6%, the remainder being water. The completed formula was coated on paper, stable in Water, at the dry coverage rate of l8-30 grams of hydrophilic layer per square meter. The coating was dried in a current of Warm, dry air and was then heated to a temperature of 240 to 270 F. by radiant heaters or other heating device. The heat treatment causes the acrylic resin to coalesce and form a continuous film thereby holding the clay and SiO particles in place and thus providing adequate Wet abrasion resistance. The thus coated paper was overcoated with a hardened gelatin-silver halide photosensitive emulsion of the type described in US. Patent 2,675,313 in the form of a layer of .005 inch thickness. The product thus prepared was useful for preparing lithographic printing plates as described above.
Example 2 The preceding was repeated except that the composition employed for the hydrophilic layer consisted for water dispersible titanium dioxide 90 parts, colloidal silica dispersion (30% Si0 312 parts, and polymethyl methacrylate emulsion parts. The ratio of Ti0 and silica to resin was approximately 6:1 dry weight. A product having properties useful for lithographic purposes was obtained.
Example 3 Example 4 A composition for applying the hydrophilic layer to paper as described in the preceding examples was prepared by adding the polymethyl methacrylate emulsion directly to the dispersion of colloidal silica, in the proportion of 400 parts of silica dispersion and 43 parts of polyalkyl acrylate emulsion. As a result the mixture had a low viscosity. Hydroxyethyl cellulose was added thereto as a thickener. The composition thus obtained was coated out onto paper having good stability in water, which was then overcoated with unhardened silver halide emulsion as described herein. A product useful for preparing lithographic printing plates was obtained.
Example 5 The above was repeated except that the composition used for the hydrophilic layer consisted of clay 50 parts, titanium dioxide 50 parts, colloidal silica dispersion 30% SiO 835 parts, polyalkyl acrylate emulsion 109 parts, and hydroxyethyl cellulose (4% solution) 160 parts.
5 A product having good characteristics for use in photolithographic procedure was obtained.
In addition to the ingredients shown in the above formulas, it is sometimes desirable to add small amounts of a commercially available Wetting agent or defoaming agent to improve the coating properties of the composition. These, however, in no way affect the hydrophilic or lithographic properties of the coatings applied.
It is thought that the hydrophilic coating as described herein functions in the following manner, but it is to be understood that the invention is not limited to the conclusions of the theoretical discussion. It is believed that the acrylic resin which is present in the hydrophilic layer as a continuous film is hydrophobic or water repellent and that it does not dissolve, swell or take up water on its surface when contacted with the fountain solutions in printing, but that it provides a tough abrasion resistant film to bind the pigment particles firmly in place. For this purpose some other resin of an alkyl ester of an acrylic acid or methacrylic acid or a styrenebutadiene or styrene-acrylic resin latex would be useful. The colloidal silica has a very small particle size, the particles being on the order of 15 millimicrons or even less in diameter. Therefore, a large surface area is presented as these particles are in discreet or separated form. Once the coating containing the colloidal silica has dried the silica becomes resistant to re-dispersing but the colloidal silica particles not completely covered with binder present a large surface area available for adsorption of moisture. It is believed that these fine silica particles adsorb moisture tenaciously, thus presenting a uniform ink repellent film of water to the press inking rollers.
When the pigment to binder ratio is too low the binder completely encompasses the SiO particles; hence, moisture is not adsorbed. With this condition complete inking of the entire plate surface occurs. When the pigment to binder ratio is between approximately 6:1 and 8:1 as specified herein, the binder spot welds the silica particles together leaving a surface of those particles free to adsorb moisture. On the other hand, when the pigment to binder ratio is much above 8:1 insufficient binder is present to bind the particles of silica and other pigment is place and the coating has a tendency to disintegrate in the printing operation.
The above described sensitized plates make possible a projection speed process for making multiple copies from microfilm records. At present, to my knowledge, there has been no other inexpensive means of making multiple copies from microfilm negatives.
I claim:
1. A lithographic printing plate, substantially free of gelatin hardener, containing in that order 1) a water resistant support, (2) a hydrophilic layer comprising an inorganic component of colloidal silica and pigment-filler, the silica constituting at least 30% thereof dry weight, and a water resistant latex resin component, the ratio of the inorganic component to the resin component being approximately 6:1, dry weight, and (3) a layer of a gelatino-silver halide emulsion containing therein a gelatin tanning silver halide developing agent.
2. A lithographic printing plate, substantially free of gelatin hardener, containing in that order a water resistant paper base, a hydrophilic layer of a mixture of titanium dioxide, clay and colloidal silica, the latter constituting at least 30% of the mixture, and a methyl methacrylate latex resin component, the ratio of the mixture of clay, titanium dioxide and colloidal silica to latex resin being within the range of approximately 6:1 to approximately 8:1, dry weight, and a layer of a gelatinosilver halide emulsion containing a tanning developer.
3. A lithographic printing plate, substantially free of gelatin hardener, containing in that order (1) a water resistant paper base support, (2) a hydrophilic layer comprising an inorganic component of colloidal silica and pigment-filler, the silica constituting at least 30% thereof dry weight, and a water resistant latex resin component, the ratio of the inorganic component to the resin component being within the range of approximately 6:1 to approximately 821, dry weight, and (3) a layer of a gelatino-silver halide emulsion containing therein a gelatin tanning silver halide developing agent.
4. A lithographic printing plate, substantially free of gelatin hardener, containing in that order (1) a water resistant support, (2) a hydrophilic layer comprising an inorganic component of colloidal silica and pigment-filler, the silica constituting at least 30% thereof dry weight, and a water resistant methyl methacrylate latex resin component, the ratio of the inorganic component to the resin component being within the range of approximately 6:1 to approximately 8:1, dry weight, and (3) a layer of a gelatino-silver halide emulsion containing therein a gelatin tanning silver halide developing agent.
5. A lithographic printing plate, substantially free of gelatin hardener, containing in that order a water resistant paper base support, a hydrophilic layer of a mixture of clay and colloidal silica, the silica constituting at least 30% thereof and a methyl methacrylate latex resin component, the ratio of the clay and colloidal silica to the latex resin component being within the range of approximately 6:1 to approximately 8:1, dry weight, and a layer of a gelatino-silver halide emulsion containing a tanning developer.
6. A lithographic printing plate, substantially free of gelatin hardener, containing in that order a water resistant paper base support, a hydrophilic layer of a mixture of titanium dioxide and colloidal silica, the latter being at least 30% thereof, and a methyl methacrylate latex resin component, the ratio of TiO and colloidal silica to the latex resin component being within the range of approximately 6:1 to approximately 8:1, dry weight, and a layer of a gelatino-silver halide emulsion containing a tanning developer.
References Cited in the file of this patent UNITED STATES PATENTS 2,698,235 Swindells Dec. 28, 1954 2,716,059 Yutzy et a1. Aug. 23, 1955 2,772,166 Fowler Nov. 27, 1956 2,805,159 Unkauf Sept. 3, 1957 2,835,575 Cowden et al. May 20, 1958

Claims (1)

  1. 3. A LITHOGRAPHIC PRINTING PLATE, SUBSTANTIALLY FREE OF GELATIN HARDENER, CONTAINING IN THAT ORDER (1) A WATER RESISTANT PAPER BASE SUPPORT, (2) A HYDROPHILIC LAYER COMPRISING AN INORGANIC COMPONENT OF COLLOIDAL SILICA THEREOF DRY WEIGHT, AND A WATER RESISTANT LATEX RESIN COMPONENT, THE RATIO OF THE INORGANIC COMPONENT TO THE RESIN COMPONENT BEING WITHIN THE RANGE OF APPROXIMATELY 6:1 TO APPROXIMATELY 8:1, DRY WEIGHT, AND (3) A LAYER OF A GELATINO-SILVER HALIDE EMULSION CONTAINING THEREIN A GELATIN TANNING SILVER HALIDE DEVELOPING AGENT.
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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3250619A (en) * 1962-06-25 1966-05-10 Eastman Kodak Co Stain-free paper
US3271151A (en) * 1965-02-08 1966-09-06 Eastman Kodak Co Photographic relief printing plate
US3312550A (en) * 1959-04-10 1967-04-04 Eastman Kodak Co Processing photographic elements containing developing agent
US3344741A (en) * 1965-09-20 1967-10-03 Dick Co Ab Receiving sheet for use as a master or copy in the dtr process
US3380824A (en) * 1964-05-12 1968-04-30 Dick Co Ab Photolithographic master and method of manufacture
US3419394A (en) * 1964-11-18 1968-12-31 Dick Co Ab Light sensitive lithographic plate of a water soluble diazo compound and a hydrophilic filler material
US3473926A (en) * 1964-05-04 1969-10-21 Eastman Kodak Co Negative material for converting from letterpress to lithography
US3607255A (en) * 1968-01-22 1971-09-21 Crown Zellerbach Corp Surfacing nonimage areas of lithographic master with hydrophilic desensitizing composition
US4588673A (en) * 1982-06-30 1986-05-13 Fuji Photo Film Co., Ltd. Retouchable mat film

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2698235A (en) * 1950-03-16 1954-12-28 Du Pont Photographic elements
US2716059A (en) * 1952-01-21 1955-08-23 Eastman Kodak Co Photographic transfer process
US2772166A (en) * 1953-02-11 1956-11-27 Eastman Kodak Co Hydrophilic compositions and their preparation
US2805159A (en) * 1953-03-02 1957-09-03 Methods for the production of diazotype
US2835575A (en) * 1955-04-05 1958-05-20 Eastman Kodak Co Photographic reproduction process

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2698235A (en) * 1950-03-16 1954-12-28 Du Pont Photographic elements
US2716059A (en) * 1952-01-21 1955-08-23 Eastman Kodak Co Photographic transfer process
US2772166A (en) * 1953-02-11 1956-11-27 Eastman Kodak Co Hydrophilic compositions and their preparation
US2805159A (en) * 1953-03-02 1957-09-03 Methods for the production of diazotype
US2835575A (en) * 1955-04-05 1958-05-20 Eastman Kodak Co Photographic reproduction process

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3312550A (en) * 1959-04-10 1967-04-04 Eastman Kodak Co Processing photographic elements containing developing agent
US3250619A (en) * 1962-06-25 1966-05-10 Eastman Kodak Co Stain-free paper
US3473926A (en) * 1964-05-04 1969-10-21 Eastman Kodak Co Negative material for converting from letterpress to lithography
US3380824A (en) * 1964-05-12 1968-04-30 Dick Co Ab Photolithographic master and method of manufacture
US3419394A (en) * 1964-11-18 1968-12-31 Dick Co Ab Light sensitive lithographic plate of a water soluble diazo compound and a hydrophilic filler material
US3271151A (en) * 1965-02-08 1966-09-06 Eastman Kodak Co Photographic relief printing plate
US3344741A (en) * 1965-09-20 1967-10-03 Dick Co Ab Receiving sheet for use as a master or copy in the dtr process
US3607255A (en) * 1968-01-22 1971-09-21 Crown Zellerbach Corp Surfacing nonimage areas of lithographic master with hydrophilic desensitizing composition
US4588673A (en) * 1982-06-30 1986-05-13 Fuji Photo Film Co., Ltd. Retouchable mat film
US4659607A (en) * 1982-06-30 1987-04-21 Fuji Photo Film Co., Ltd. Retouchable mat film

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