Classifications

• • 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
  • B41N3/08—Damping; Neutralising or similar differentiation treatments for lithographic printing formes; Gumming or finishing solutions, fountain solutions, correction or deletion fluids, or on-press development

Definitions

• This invention concerns a deletion fluid and a process of using the deletion fluid to delete printing areas from a lithographic plate comprising an oleophilic oxidized image area in hardened colloid.
• a developable silver halide image is formed by means of exposure to a line or half-tone subject in a hardened hydrophilic organic colloid-silver halide emulsion such as a gelatino-silver halide emulsion.
• Development is carried out using polyhydroxybenzene silver halide developer, which is either present in the emulsion or a layer effectively adjacent thereto.
• developer is oxidized in the development reaction in the presence of the hydrophilic organic colloid vehicle present in the silver halide emulsion layer, an oleophilic image is formed.
• desired lithographic reproduction which is negative to the original subject is obtained.
• the photographic element described above may contain, in addition, a fogged silver halide emulsion as the uppermost layer.
• a fogged silver halide emulsion as the uppermost layer.
• the developing agent reacts with the sensitive lower silver halide emulsion layer to form the negative image, and the unused silver halide developing agent present in the unexposed areas of the sensitive lower silver halide emulsion layer then migrates upward to the fogged silver halide emulsion layer, and when oxidized in the presence of a hydrophilic organic colloid present in this layer, forms an oleophilic image in the surface which is positive in respect to the original subject.
• One of the temporary deletion systems operates by the precipitation of a hydrophilic pigment in the area to be deleted so that the hydrophobic character of the image is overcome. Such precipitates being loosely bound in the gelatin structure are soon extracted and the hydrophobic image prevails. If a replenishment is carried out through the fountain solution so that new precipitate is continually being formed then permanent deletion can be accomplished. Such systems require special fountain solution preparations which often are not compatible with other lithographic plates.
• an aqueous solution containing a hardenable polymer can be used to delete the image on 3,276,351 Patented Oct. 4, 1966 a processed photographic lithographic plate by crosslinking of the polymer with the oleophilic image.
• One object of this invention is to provide a deletion solution for use in deleting the image from a photographic lithographic plate comprising a tanned image area in hardened colloid.
• An additional object is to provide a process for deleting the image from a photographic lithographic plate comprising a tanned image area in hardened colloid.
• An additional object is to provide a method of deleting an image from a hardened gelatin colloid layer containing therein oleophilic areas by means of a hardenable polymer which is crosslinked on the areas to be deleted.
• a further object is to provide a deletion method which can be used with conventional fountain solutions and which results in permanent deletion by forming a hydrophilic polymer on the areas to be deleted.
• the above objects are attained by treating the surface of the plate with a solution of at least 2 percent watersoluble polymer, for example, water-soluble copolymer of acrylamide and N-methacryloyl-N-cyano-acetyl hydrazine.
• the useful range is from 2 to 8 percent. Much larger concentrations may be used if desired with good deletion.
• the area to be deleted is then coated with .a solution of cross-linking agent, such as, for example, a 10 percent aqueous formaldehyde solution. Sufficient cross-linking agent must be used, but the particular amount may be varied depending upon the polymer used, the cross-linking agent, etc.
• the water-soluble polymer which may be used in carrying out the invention is a matter of choice, provided that it results in covering the area to be treated with a hydrophilic polymer which is firmly bound to the lithographic surface in the area from which the hydrophobic printing area is to be omitted.
• the hydrophilic polymer covers the formerly oleophilic area so that printing no longer takes place in all of those areas wherein the polymer is firmly bound to the gelatin.
• a large number of water-soluble polymers which are capable of being cross-linked or hardened may be used including, for example, polyvinyl alcohol, copolymers of acrylamide and N-cyanoacetyl-N'-methacryloyl hydrazine with 5090 mole percent acrylamide, copolymers of N- glycyl-N'-methacryloyl hydrazine hydrochloride with sodium-3-acryloyloxypropane-lssulfonate (-95 mole percent) or with acrylamide (70 97.5 mole percent), etc.
• the cross-linkable polymer and the cross-linking agent are mixed together before applying to the lithographic plate.
• deletion fluid may contain other components such as thickener, and the like, provided these components do not react adversely with the polymer or its cross-linking reaction.
• Suitable thickneners include hydrophilic organic colloids such as, for example, gelatin, hydroxyethyl cellulose, carboxymethyl cellulose, starch, guar gum, etc.
• the deletion fluid may be applied by a swab, brush, quill, sponge, or by other means which will delineate the area to be deleted. If prepared in a viscous form, it may be squeezed from a compressible tube. Although it is preferable that the deletion fluid may be applied to the moist plate, it can be applied to a plate which is in a dried-down condition. However, the ink should be removed from any area to be treated sufficiently to insure adhesion to the gelatin surface.
• Example 1 A lithographic plate was prepared as follows according to Yackel et al. US. Patent 3,146,104.
• a photographic emulsion was prepared by combining the following ingredients:
• Parafiin dispersion prepared as follows: 80 g. molten parafiin dispersed in 400 cc. photographic The emulsion was coated at 6.5 grams per sq. foot on a film base and dried.
• the film was exposed to a line negative, then activated for seconds in a 4 percent solution of sodium carbonate monohydrate.
• the development was stopped in an acidic stop bath by a 20-second immersion. After drying, a portion of the image area was treated in the following way to render it non-printing.
• the polymer was prepared as in Example 12 of U.S. Patent 2,940,956.
• Example 2 As a matter of convenience in the application of the polymer solution to the lithographic printing plate, pigment may be added. Barium sulfate was used as a suitable pigment. Similarly, a dye may also be used for purposes of identifying the extent of coverage during the application step as illustrated below.
• T o 15 grams of the polymer used in Example 1, 10 percent aqueous solution was added ml. of distilled water and 10 grams of a 30 percent BaSO aqueous slurry. This was ball milled for 1 /2 hours.
• Example 3 A printing plate prepared by the transfer process described in Example 7 of U.S. Patent 3,146,104 was run in the customary manner to produce good copies.
• a solution containing 2 ml. of a 9 percent solution of a poly(vinyl acetal) of 2,4 disulfobenzaldehyde at pH 0.7 plus 2 drops of a wetting agent was rubbed into an inking area with a cotton swab. Over this and while still wet, a solution of 5 percent glutaraldehyde in distilled water was also rubbed in with a cotton swab. After waiting 30 seconds, a continuation of the press run showed no printing where the reactants had been applied while normal printing occurred elsewhere.
• the reverse order of application was done.
• the wetting agent solution was added to the glutaraldehyde solution and this was applied to the plate with the ink removed.
• the polymer solution was added over the glutaraldehyde. This was dried for 15 seconds in warm air from a gun type hair dryer. Excellent deletion was observed.
• Example 4 The process of our invention is applicable to all those polymer-hardener combinations which provide crosslinking of a hydrophilic polymer to the gelatin of the processed plate of the type described in U.S. Patent 3,146,104. Any polymer-copolymer combination which contains suflicient sites which may be crosslinked to the gelatin plate surface to provide a hydrophilic surface may be used.
• Such hydrophilic polymers may be selected from those which contain active hydrogen atoms, e.g., active methylene, hydroxyl, amino, amido and carboxyl groups.
• Suitable hardening agents such as dialdehydes, dihydric alcohols, diamines, bis-epoxides, bis-aziridines, dicarboxylic esters, diisocyanates including the bisulfite derivatives thereof, etc., may be used in place of formaldehyde.
• Example 5 In some instances it is advantageous to apply a mixture of the hardener and the polymer at the same time.
• the following example illustrates such an embodiment.
• a printing plate prepared as in Example 4 of U.S. Patent 3,146,104 was run on a Multilith press with normal treatment to produce good copies.
• Example 6 Fifty-eight grams of a 10% aqueous solution of poly(vinyl alcohol), 100% hydrolyzed, was combined with 5.8 grams of titanium oxide and ball milled for 20 hours. A second dispersion was made in a similar manner except that 88% hydrolyzed poly(vinyl alcohol) was utilized therein.
• Printing plates prepared as in Example 4 of US. Patent 3,146,104 was run on a Multilith press with normal treatment to produce good copies.
• Example 7 Other embodiments employing a hardened colloid layer containing an oleophilic tanned image are also treated with the deletion fluid with satisfactory results. These include those of the positive-positive process, wherein the developer is in a layer under the silver halide emulsion and wherein a fogged silver halide emulsion is coated over the positive-negative element, as well as those wherein the image is obtained by the diffusion transfer process, by the colloid transfer process, etc.
• the lithographic plate carries a gelatin layer which contains oxidation agents which render the gelatin oleophilic in the image area and the gelatin has a hardness equivalent to that of a gelatin layer containing from 2 grams to about 15 grams of dry formaldehyde per pound of gelatin, i.e., it should have a melting point in water greater than 150 F. and preferably greater than 200 F.
• Example 8 Lithographic plates prepared as in Example 1 were taken olf the lithographic press after having made 40 good copies and subjected to treatment as in Example 1.
• Commercial bleach comprising a bic-hromate-sulfuric acid combination gave bad toning.
• Colloidal silica in an aqueous suspension resulted in deleting the image temporarily but it returned after several prints. Excess silica builds up in the fountain, causing an obliteration of the complete image on the plate and contaminating the press.
• the support on which the lithographic plate is coated may be any of the customary supports used for lithographic plates.
• the components of the sensitive elements of the lithographic plate can be varied appreciably in the known photographic silver halide emulsions such as silver chloride, silver bromide, silver iodide, silver bromochloride, silver bromoiodide, and silver bromochloroiodide emulsions.
• Direct positive emulsions may be used such as those described in Leermaker U.S. Patent 2,184,013; Kendall and Hill U.S. 2,541,472; Fallesen U.S. 2,497,875, etc.
• hydrophilic organic colloid vehicles can be used for the silver halide emulsions for making the plate.
• Proteins such as gelatin, soy bean protein, casein, as well as synthetic organic colloids which are hydrophilic, such as polyvinyl alcohol, hydrolyzed cellulose esters, etc., may be used to the extent that they form the desired oleophilic image with the oxidized developing agent in the development reaction.
• lithographic plates prepared by other methods may also be used on lithographic plates prepared by other methods than those described above.
• lithographic plates made by using light-sensitive polymers for example, diazo sensitized, electrostatically formed plates, mechanically prepared plates, etc. may be used providing adhesion is obtained between the hydrophilic polymer and the areas to be deleted.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top layer capable of adherence to a crosslinkable hydrophilic organic polymer by means of a crosslinking agent, comprising coating the image area to be rendered hydrophilic with an aqueous solution of a crosslinkable hydrophilic organic polymer and a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top hydrophilic colloid layer containing an oleophilic image area, comprising coating the image area to be rendered hydrophilic with an aqueous solution of a crosslinkable hydrophilic organic polymer and a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top layer comprising gelatin having a hardness equivalent to that of a gelatin layer containing from 2 grams to about 15 grams of dry formaldehyde per pound of gelatin and containing in the gelatin layer an oleophilic tanned gelatin image area, comprising coating the image area to be rendered hydrophilic with an aqueous solution of a crosslinkable hydrophilic organic polymer and a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top layer capable of adherence to a crosslinkable hydrophilic organic polymer by means of a crosslinking agent, comprising coating the image area to be rendered hydrophilic with an aqueous solution of a crosslinkable hydrophilic organic polymer and then coating the image area with a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a'support having thereon a top hydrophilic colloid layer containing an oleophilic image area, comprising coating the image area to 'be rendered hydrophilic with an aqueous solution of a crosslinkable hydrophilic organic polymer and then coating the image area with a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top layer comprising gelatin having a hardness equivalent to that of a gelatin layer containing from 2 grams to about 15 grams of dry formaldehyde per pound of gelatin and containing in the gelatin layer an oleophilic tanned gelatin image area, comprising coating the image area to be rendered hydrophilic with an aqueous solution of a crosslinkable hydrophilic organic polymer and then coating the image area with a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top layer capable of adherence to a crosslinkable hydrophilic organic polymer by means of a crosslinking agent, comprising coating the image area to be rendered hydrophilic with an aqueous solution of a copolymer of acrylamide and N-cyanoacetyl-N-methacryloyl hydrazine and then coating the image area with a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top hydrophilic colloid layer containing an oleophilic image area, comprising coating the image area to be rendered hydrophilic with an aqueous solution of a copolymer of acrylamide and N-cyanoacetyl-N- methacryloyl hydrazine and then coating the image area with a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top layer comprising gelatin having a hardness equivalent to that of a gelatin layer containing from 2 grams to about 15 grams of dry formaldehyde per pound of gelatin and containing in the gelatin layer an oleophilic tanned gelatin image area comprising coating the image area to be rendered hydrophilic with an aqueous solution of a copolymer of acrylamide and N- cyanoacetyl-N'-methacryloyl hydrazine and then coating the image area with a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top layer capable of adherence to a crosslinkable hydrophilic organic polymer by means of a crosslinking agent, comprising coating the image area to be rendered hydrophilic with an aqueous solution of poly(vinyl acetal) of 2,4-disulfo-benzaldehyde and then coating with a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top layer capable of adherence to a crosslinkable hydrophilic organic polymer by means of a crosslinking agent, comprising coating the image area to be rendered hydrophilic with an aqueous solution of poly(vinyl alcohol) and then coating with a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top layer comprising gelatin having a hardness equivalent to that of a gelatin layer containing from 2 grams to about 15 grams of dry formaldehyde per pound of gelatin and containing in the gelatin layer an oleophilic tanned gelatin image area, comprising coating the image area to be rendered hydrophilic with an aqueous solution of poly(vinyl acetal) of 2,4-disulfo- 'benzaldehyde and then coating with a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top layer capable of adherence to a crosslinkable hydrophilic organic polymer by means of a crosslinking agent, comprising coating the image area to be rendered hydrophilic with an aqueous solution of poly(vinyl acetal) of 2,4-disulfobenzaldehyde and a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top hydrophilic colloid layer containing an oleophilic image area, comprising coating the image area to be rendered hydrophilic with an aqueous solution of poly(vinyl alcohol) and a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top layer comprising gelatin having a hardness equivalent to that of a gelatin layer containing from 2 grams to about 15 grams of dry formaldehyde per pound of gelatin and containing in the gelatin layer an oleophilic tanned gelatin image area, comprising coating the image area to be rendered hydrophilic with an aqueous solution of poly(vinyl acetal) of 2,4-disulfobenzaldehyde and a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top layer capable of adherence to a crosslinkable hydrophilic organic polymer by means of a crosslinking agent, comprising coating the image area to be rendered hydrophilic with an aqueous solution of a hydrophilic polymer containing at least one active hydrogen atom which can be crosslinked to the top layer to provide a hydrophilic surface and then coating with a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top hydrophilic colloid layer containing an oleophilic image area, comprising coating the image area to be rendered hydrophilic with an aqueous solution of a hydrophilic polymer containing at least one active hydrogen atom which can be crosslinked to the top layer to provide a hydrophilic surface and then coating with a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top layer comprising gelatin having a hardness equivalent to that of a gelatin layer containing from 2 grams to about 15 grams of dry formaldehyde per pound of gelatin and containing in the gelatin layer an oleophilic tanned gelatin image area comprising coating the image area to be rendered hydrophilic with an aqueous solution of a hydrophilic polymer containing at least one active hydrogen atom which can be crosslinked to the top layer to provide a hydrophilic surface and then coating with a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top hydrophilic colloid layer containing an oleophilic image area, comprising coating the image area to be rendered hydrophilic with an aqueous solution of a hydrophilic polymer containing at least one active hydrogen atom which can be crosslinked to the top layer and a crosslinking agent.
• a process for rendering hydrophilic an image area on a lithographic printing plate comprising a support having thereon a top layer comprising gelatin having a hardness equivalent to that of a gelatin layer containing from 2 grams to about 15 grams of dry formaldehyde per pound of gelatin and containing in the gelatin layer an oleophilic tanned gelatin image area, comprising coating the image area to be rendered hydrophilic with an aqueous solution of a hydrophilic polymer containing at least one active hydrogen atom which can be crosslinked to the top layer and a crosslinking agent.

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• Compositions Of Macromolecular Compounds (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)
• Printing Plates And Materials Therefor (AREA)

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Cited By (3)

Citations (2)

• 1965
  • 1965-08-17 US US480510A patent/US3276361A/en not_active Expired - Lifetime
• 1966
  • 1966-08-12 BE BE685502D patent/BE685502A/xx unknown

Patent Citations (2)

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