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

• the dampening solution used in the present invention comprises a (combination of) preservative(s), so that the composition is effective for ⁇ controlling various kinds of mold, bacteria and yeast.
• a lithographic printing plate is obtained by means of the DTR-process using an imaging element comprising on a support in the order given a silver halide emulsion layer and a layer containing physical development nuclei in water permeable relationship with said emulsion layer.
• compositions, preparation and coating of silver halide emulsions suitable for use in accordance with the present invention can be found in e.g. Product Licensing Index, Vol. 92, December 1971, publication 9232, p. 107-109.
• the hydrophilic layers of the photographic element can be hardened with appropriate hardening agents such as those of the vinylsulfone type e.g. methylenebis(sulfonylethylene), aldehydes e.g. formaldehyde, glyoxal, and glutaraldehyde, N-methylol compounds e.g. dimethylolurea and methyloldimethylhydantoin, active halogen compounds e.g. 2,4-dichloro-6-hydroxy-s-triazine, and mucohalogenic acids e.g. mucochloric acid and mucophenoxychloric acid.
• hardeners can be used alone or in combination.
• the binders can also be hardened with fast-reacting hardeners such as carbamoylpyridinium salts of the type, described in US 4,063,952.
• a further suitable type of silver halide solvents are thioether compounds.
• thioethers correspond to the following general formula: Z-(R 1 -S) t -R 2 -S-R 3 -Y wherein Z and Y each independently represents hydrogen, an alkyl group, an amino group, an ammonium group, a hydroxyl, a sulfo group, a carboxyl, an aminocarbonyl or an aminosulfonyl, R 1 , R 2 and R 3 each independently represents an alkylene that may be substituted and optionally contain an oxygen bridge and t represents an integer from 0 to 10.
• Examples of thioether compounds corresponding to the above formula are disclosed in e.g. US-P-4,960,683 and EP-A 547,662, which therefor are incorporated herein by reference.
• silver halide solvents are meso-ionic compounds.
• Preferred meso-ionic compounds for use in connection with the present invention are triazolium thiolates and more preferred 1,2,4-triazolium-3-thiolates.
• the meso-ionic compound may be incorporated in one or more layers comprised on the support of the imaging element.
• the meso-ionic compound is in that case preferably contained in the imaging element in a total amount between 0.1 and 10 mmol/m 2 , more preferably between 0.1 and 0.5 mmol/m 2 and most preferably between 0.5 and 1.5 mmol/m 2 . More details are disclosed in EP-A-0,554,585
• the alkaline processing liquid used in accordance with the present invention preferably has a pH between 9 and 14 and more preferably between 10 and 13. Said pH may be established by an organic or inorganic alkaline substance or a combination thereof.
• Suitable inorganic alkaline substances are e.g. potassium or sodium hydroxide, carbonate, phosphate etc..
• Suitable organic alkaline substances are e.g. alkanolamines. In the latter case the alkanolamines will provide or help maintain the pH and serve as a silver halide complexing agent.
• At least the auxiliary developing agents are preferably incorporated into the photographic material, preferably in the silver halide emulsion layer of the photographic material, in an amount of less than 150 mg/g of silver halide expressed as AgNO 3 , more preferably in an amount of less than 100 mg/g of silver halide expressed as AgNO 3 .
• the alkaline processing liquid used for developing an imaging element as described above preferably also contains hydrophobizing agents for improving the hydrophobicity of the silver image obtained in the image receiving layer.
• the hydrophobizing agents used in connection with the present invention are compounds that are capable of reacting with silver or silver ions and that are hydrophobic i.e. insoluble in water or only slightly soluble in water. Generally these compounds contain a mercapto group or thiolate group and one or more hydrophobic substituents e.g. an alkyl group containing at least 3 carbon atoms.
• a spreading agent or surfactant in the alkaline processing liquid to assure equal spreading of the alkaline processing liquid over the surface of the photographic material.
• a surfactant should be stable at the pH of the alkaline processing liquid and should assure a fast overall wetting of the surface of the photographic material.
• a surfactant suitable for such purpose is e.g. a fluor containing surfactant such as e.g. C 7 F 15 COONH 4 . It is furthermore advantageous to add glycerine to the alkaline processing liquid so as to prevent crystallization of dissolved components of said alkaline processing liquid.
• a neutralization liquid generally has a pH between 5 and 8.
• the neutralization liquid preferably contains a buffer e.g. a phosphate buffer, a citrate buffer or mixture thereof.
• the neutralization solution can further contain bactericides, substances which influence the hydrophobic / hydrophilic balance of the printing plate obtained after processing of the DTR element, e.g. hydrophobizing agents as described above, silica and wetting agents, preferably compounds containing perfluorinated alkyl groups.
• Said hydrophilic surface of a support can be a hardened hydrophilic layer, containing a hydrophilic binder and a hardening agent coated on a flexible support.
• Flexible supports e.g. a paper support or a resin support are described above.
• Said hydrophilic surface of a support may be a hydrophilic metallic support e.g. an aluminum foil.
• the preparation of aluminum or aluminum alloy foils for lithographic offset printing comprises the following steps : graining, anodizing, and optionally sealing of the foil.
• the aluminum foil has a roughness with a CLA value between 0.2 and 1.5 ⁇ m, an anodization layer with a thickness between 0.4 and 2.0 ⁇ m and is sealed with an aqueous bicarbonate solution.
• the electrochemical graining process is preferred because it can form a uniform surface roughness having a large average surface area with a very fine and even grain which is commonly desired when used for lithographic printing plates.
• Electrochemical graining can be conducted in a hydrochloric and/or nitric acid containing electrolyte solution using an alternating or direct current.
• aqueous solutions that can be used in the electrochemical graining are e.g. acids like HCl, HNO 3 , H 2 SO 2 , H 3 PO 4 , that if desired, contain additionally one or more corrosion inhibitors such as Al(NO 3 ) 3 , AlCl 3 , boric acid, chromic acid, sulfates, chlorides, nitrates, monoamines, diamines, aldehydes, phosphates, H 2 O 2 , etc. ...
• Electrochemical graining in connection with the present invention can be performed using single-phase and three-phase alternating current.
• the voltage applied to the aluminum plate is preferably 10-35 V.
• a current density of 3-150 Amp/dm 2 is employed for 5-240 seconds.
• the temperature of the electrolytic graining solution may vary from 5-50°C.
• Electrochemical graining is carried out preferably with an alternating current from 10 Hz to 300 Hz.
• the aluminum foil may be subjected to a degreasing treatment with a surfactant and/or an aqueous alkaline solution.
• Suitable acids for use in the aqueous etch solution are preferably inorganic acids and most preferably strong acids.
• the total amount of acid in the aqueous etch solution is preferably at least 150g/l.
• the duration of chemical etching is preferably between 3s and 5min.
• the aluminum foil is anodized which may be carried out as follows.
• sealing may be applied to the anodic surface.
• Sealing of the pores of the aluminum oxide layer formed by anodization is a technique known to those skilled in the art of aluminum anodization. This technique has been described in e.g. the "Belgisch-Nederlands tijdschrift voor Oppervlaktetechnieken van materialen", 24ste jaargang/januari 1980, under the title "Sealing-kwaliteit en sealing-controle van geanodiseerd Aluminum". Different types of sealing of the porous anodized aluminum surface exist.
• said sealing is performed by treating a grained and anodized aluminum support with an aqueous solution containing a bicarbonate as disclosed in EP-A 567178, which therefor is incorporated herein by reference.
• each of the above described steps is separated by a rinsing step to avoid contamination of the liquid used in a particular step with that of the preceding step.
• the anodization layer may be coloured in the mass with an antihalation dye or pigment e.g. as described in JA-Pu-58-14,797.
• a hydrophilic colloid may be used, usually a protein, preferably gelatin.
• Gelatin can, however, be replaced in part or integrally by synthetic, semi-synthetic, or natural polymers.
• the silver halide emulsion layer contains at least one gelatin species whereof a 10 % by weight aqueous solution at 36 °C and pH 6 has a viscosity lower than 20 mPas at a shearing rate of 1000 s -1 combined with a gelatin of a higher viscosity.
• the weight ratio of said low viscosity gelatin versus the gelatin of a higher viscosity is preferably > 0.5.
• the gelatin layer(s) is(are) substantially unhardened.
• substantially unhardened means that when such gelatin layer is coated on a subbed polyethylene terephtalate film base at a dry thickness of 1.2 g/m 2 , dried for 3 days at 57 C° and 35% R.H. and dipped in water of 30 C°, said gelatin layer is dissolved for more than 95 % by weight within 5 minutes.
• the imaging element of the present embodiment may be imaged using a camera-exposure or a scanning exposure as described above followed by a development step in the presence of development agent(s) and silver halide solvent(s) according to the invention so that a silver image is formed in the physical development nuclei layer. Subsequently the silver halide emulsion layer and any other optional hydrophilic layers are removed by e.g. rinsing the imaged element with water, preferably between 30°C and 50°C so that the silver image is exposed.
• a layer between the hydrophilic surface of a support and the silver halide emulsion layer comprising a hydrophilic non-proteinic film-forming polymer e.g. polyvinyl alcohol, polymer beads e.g. poly(meth)acrylate beads, mixtures thereof, particles of a water insoluble inorganic compound having a number average size not lower than 0.1 ⁇ m or alkali insoluble non-polymeric organic compounds having a melting point of at least 50°C and a number average size between 0.1 ⁇ m and 10 ⁇ m.
• a hydrophilic non-proteinic film-forming polymer e.g. polyvinyl alcohol
• polymer beads e.g. poly(meth)acrylate beads, mixtures thereof, particles of a water insoluble inorganic compound having a number average size not lower than 0.1 ⁇ m or alkali insoluble non-polymeric organic compounds having a melting point of at least 50°C and a number average size between 0.1 ⁇ m and 10 ⁇ m
• said exposed imaged surface of the hydrophilic support is treated with a finisher to enhance the water-receptivity of the non-image areas and to make the image areas oleophilic ink-receptive.
• the lithographic composition often called finisher comprises at least one compound enhancing the ink-receptivity and/or lacquer-receptivity of the silver image and at least one compound that improves the ink-repelling characteristics of the hydrophilic surface.
• Suitable ingredients for the finisher are e.g. organic compounds containing a mercapto group such as the hydrophobizing compounds referred to hereinbefore for the alkaline solution.
• Said (a) hydrophobizing agent(s) is(are) comprised in the finisher preferably in a total concentration between 0.1 g/l and 10 g/l, more preferably in a total concentration between 0.3 g/l and 3 g/l.
• Additives improving the oleophilic ink-repellency of the hydrophilic surface areas are e.g. carbohydrates such as acid polysaccharides like gum arabic, carboxymethylcellulose, sodium alginate, propylene glycol ester of alginic acid, hydroxyethyl starch, dextrin, hydroxyethylcellulose, polyvinyl pyrrolidone, polystyrene sulphonic acid, polyvinyl alcohol and preferably polyglycols, being the reaction products of ethyleneoxide and/or propyleneoxide with water or an alcohol.
• hygroscopic substances e.g. sorbitol, glycerol, tri(hydroxyethyl)ester of glycerol, and turkish red oil may be added.
• the lithographic plate in a following step is mounted on a lithographic press and treated with a diluted dampening solution as described above and with a lithographic ink in order to print.
• any of the conventional lithographic inks can be used in the present invention.
• the lithographic inks include black ink, general process color ink, pantone color ink, magnetic ink, gold and silver ink, UV curable ink, ink for synthetic paper, fluoresent ink and metallic ink etc..
• the dampening system suitable for use in the present invention is preferably an integrated system, whereby the dampening solution and the ink are brought into contact with each other before applying them to the lithographic plate e.g. by feeding the dampening solution to inked rollers.
• the dampening system used in the present invention may also be a conventional separated system, whereby the dampening solution is fed to the lithographic plate using fabric covered rollers independent of the inked rollers.
• hybrid dampening systems may be used in the present invention, whereby some dampening solution is brought into contact with the ink before applying the mixture to the lithographic plate and some dampening solution is fed directly to the lithographic plate using rubber rollers independent of the inked rollers.
• any lithographic printing press can be used.
• Printing can be effected on any ink-receptive element i.a. depending on the required printing effect. In general, paper is used but also cardboard can be used.
• a concentrated dampening solution I was prepared by adding to 700 ml of demineralized water 12 g of NaH 2 PO 4 .2H 2 O, 1 g of citric acid, 0.7 g of sodium hydroxyde. 7 ml of a 5% solution of 5-bromo-5-nitro-1,3-dioxane, 130 ml of dipropylene glycol, 50 ml of Levasyl 200S-30 (a 30% solution of an acid stabilised colloidal silica with a specific surface of 200 m 2 /g, corresponding to a number average size between 0.010 and 0.015 ⁇ m, sold by Bayer A.G., Germany) and water to make 1000 ml. The pH of said concentrated dampening solution was adjusted to 5.6 by adding the necessary amount of a solution of 40% of NaOH.
• Concentrated dampening solutions II was prepared in an identical way except that Levasyl 200S-30 was replaced by 50 ml of Levasyl 200A-30 (a 30 % solution of a colloidal silica with a specific surface of 200 m 2 /g, sold by Bayer A.G., Germany). Said Levasyl 200A-30 has an aluminum oxyde modified surface wherein the ratio between gram atom Al and gram atom Si is equal to 0.0074 or A (200 m 2 /g)/27,000.
• a base layer coating solution was prepared having the following composition: gelatin 5.5% carbon black 0.76% silica particles (5 ⁇ m) 1.6%
• the silver halide emulsion coating solution was coated simultaneously with the base layer coating solution by means of the slide hopper coating technique to a polyethylene terephthalate support provided with a pack of two backing layers such that the base layer coating was coated directly to the side of the support opposite to the side containing said backing layers.
• the silver halide emulsion layer was coated such that the silver halide coverage expressed as AgNO 3 was 1.5g/m 2 and the gelatin content was 1.5g/m 2 .
• the silver halide emulsion layer further contained 0.15g/m 2 of 1-phenyl-4,4'-dimethyl-3-pyrazolidone and 0.25g/m 2 of hydroquinone.
• the base layer was coated such that the amount of gelatin in the coated layer was 3g/m 2 .
• the layer nearest to the support of the backing layer pack contained 0.3 g/m 2 of gelatin and 0.5 g/m 2 of the antistatic agent co(tetraallyloxyethane / methacrylate / acrylic acid-K-salt) polymer.
• the second backing layer contained 4 g/m 2 of gelatin, 0.15 g/m 2 of a matting agent consisting of transparent spherical polymeric beads of 3 micron average diameter according to EP-A-080,225, 0.05 g/m 2 of hardening agent triacrylformal and 0.021 g/m 2 of wetting agent F 15 C 7 -COONH 4 .
• the thus obtained element was dried and subjected to a temperature of 40°C for 5 days and then the silver halide emulsion layer was overcoated with a layer containing as physical development nuclei 0.7 mg PdS/m 2 , hydroquinone at 0.4g/m 2 and formaldehyde at 100mg/m 2 .
• the thus obtained element was dried and again subjected to a temperature of 40°C for 5 days.
• the above described imaging element was image-wise exposed and processed with the above described activator for 10 seconds at 30°C, subsequently neutralized at 25 °C with the neutralization solution described above and dried.
• a first printing plate thus prepared was mounted on an offset printing machine HEIDELBERG GTO-52, marketed by Heidelberg, A.G., Germany, equipped with a DAHLGREN " 3-roll " dampening system, and was used for printing 1000 cppies.
• the above mentioned dampening solution I was used at a 3 % concentration in an aqueous solution containing 10 % isopropanol as fountain solution.
• the ink used was K+E 2F713, marketed by Kast and Ehinger, Germany. A compressible rubber blanket was used.

Landscapes

• Photosensitive Polymer And Photoresist Processing (AREA)
• Printing Plates And Materials Therefor (AREA)
• Printing Methods (AREA)

Priority Applications (4)

Applications Claiming Priority (1)

Publications (2)

Family

ID=8220503

Family Applications (1)

Country Status (3)

Cited By (2)

Citations (3)

• 1995
  • 1995-07-18 DE DE1995610341 patent/DE69510341T2/de not_active Expired - Fee Related
  • 1995-07-18 EP EP19950201974 patent/EP0754565B1/de not_active Expired - Lifetime
• 1996
  • 1996-07-17 JP JP20547696A patent/JPH0930143A/ja active Pending

Patent Citations (3)

Also Published As

Similar Documents

Legal Events