Classifications

• • 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
  • G03F7/016—Diazonium salts or compounds
  • G03F7/021—Macromolecular diazonium compounds; Macromolecular additives, e.g. binders
  • G03F7/0212—Macromolecular diazonium compounds; Macromolecular additives, e.g. binders characterised by the polymeric binder or the macromolecular additives other than the diazo resins or the polymeric diazonium compounds
  • G03F7/0215—Natural gums; Proteins, e.g. gelatins; Macromolecular carbohydrates, e.g. cellulose; Polyvinyl alcohol and derivatives thereof, e.g. polyvinylacetals

Definitions

• ABSTRACT Inexpensive positive-imaging sensitized plates easily convertible into good and durable planographic printing fonns by imagewise exposure and development with an aqueous buffered phloroglucinol solution at a pH of 4 to 8, are provided by forming on a paper support a planographic coating consisting essentially of a finely divided inorganic filler and, as a hydrophilic organic binder, water-insolubilized polyvinyl alcohol having a degree of hydrolysis greater than 98 percent, and sensitizing this coating with a benzene diazonium salt of high coupling activity.
• the coating is formed from an aqueous dispersion containing a cross linking agent for insolubilizing the polyvinyl alcohol, and is dried and hardened to a Cobbtest water absorbing capacity of less than 6.
• the plates give extremely long-running offset printing forms when exposed through a transparent original, and even when the original is a typewritten translucent sheet.
• This invention relates to planographic printing plates of the kind having on a paper or like support a light-sensitive planographic coating consisting essentially of a finely divided inorganic filler and a water-insolubilized hydrophilic organic binder sensitized with a light-sensitive benzene diazonium salt, and to a process for producing planographic printing forms by development of the coatings of such plates, after imagewise exposure thereof, so as to convert them into oleophilic azodyestuff images.
• printing forms are used in which an oleophilic (ink receptive) image is present on a hydrophilic background.
• the oleophilic image is developed, for instance, on a printing plate made by applying and sensitizing a planographic coating on. a support such as an anodically oxidized aluminum foil or suitable paper.
• the printing form is wetted with water and ink, the water being selectively taken up by the hydrophilic areas and the ink by the oleophilic areas of the printing surface.
• the plate starts toning." That is, the hydrophilic areas will take up ink to some extent, either at spots where the water film is interrupted or even over their whole surface, and the ink so taken up objectionably blemishes corresponding areas of the prints obtained.
• the planographic paper plate consists of a paper support and a single coating thereon which contains a finely divided inorganic pigment and a water-insolubilized hydrophilic organic binding agent.
• Such single-coated plates are suitable for making a few hundred prints at most When it is desired to obtain larger runs with a planographic paper plate, one or more water repellent coatings and/or anchoring coatings are usually applied between the planographic coating and the support.
• the substances mentioned for use as the pigment in such coatings are, for instance: zinc oxide, titanium dioxide, barium sulfate, antimony trioxide, carbon black, calcium carbonate, magnesium carbonate, lithopone, aluminum oxide, calcium fluoride, magnesium oxide, calcium oxide, silica, kaolin, bentonite, aluminum silicate, diatomaceous earth, satin white, talcum, fullers earth, Georgia clay or calcined clay.
• binding agents for such coatings are, among others: gelatin, casein, 'zein, soyaprotein albumin, animal glue, hydroxyethyl cellulose, sulfoethyl cellulose, carboxymethyl cellulose cellulose sulfate, methyl cellulose, oxidized cellulose, carboxymethyl hydroxyethyl cellulose, methyl ethyl cellulose starch, hydroxyethyl starch, glucosan-2- mono-carbamate, oxidized starch, starch-acetate, enzymeconverted starch, acid-modified starch, chlorinated starch, amioca starch, starch glycolate, reaction products of hydroxyethyl starch with aminoformaldehyde resins, pectin derivatives, alginic acids, gum arabic, carragenan, chitosan, dextrin, dextrane, locust bean gum, tragacanth gum, mesquite gum, karay
• he oleophilic image in the planographic coating can be formed either mechanically (for instance by typewriting) or photographically.
• a diazo resin or an o-naphthoquinone diazide is generally used as a light-sensitive substance.
• diazo resins condensation products of an aromatic diazo compound such as p-diazodiphenyl amine with an aldehyde such as formaldehyde. Upon exposure the diazo resin yields oleophilic decomposition products, and the printing form then is developed by washing away the non-decomposed diazo compound with water. Thus, printing plates sensitized'with diazo resins are normally negative working
• the o-naphthoquinone-diazides used in practice are mostly either water-insoluble esters that dissolve readily in organic solvents, or amides of o-naphthoquinone-diazide-sulfonic or carboxylic acids.
• printing plates sensitized with o-naphthoquinone-diazides are either positive ornegative working.
• the development of them can be effected by dissolving selectively either the nondecomposed o-naphthoquinone diazide or its photmdecomposition product.
• positive working planographic plates of high quality can be made.
• German Pat. No. 857 888 describes a process in which an anodically oxidized aluminum plate sensitized with a benzene diazonium salt, such as the chlorozincate of 4-diazonium-N- methylaniline or of 4-diazonium-2-methyl-N-ethyl aniline, is imagewise exposed and subsequently developed, according to a diazotype method, so as to convert the non-decomposed diazonium salt into an oleophilic azo-dyestuff. If the light-sew sitive coating contains an azo-coupling component, the azodyestuff is formed by exposing the plate to ammonia vapor.
• a benzene diazonium salt such as the chlorozincate of 4-diazonium-N- methylaniline or of 4-diazonium-2-methyl-N-ethyl aniline
• the printing form can also be developed with a solution containing an azo-coupling component which preferably is a polyvalent aromatic hydroxyl compound such as 2, 4, 2, 4-tetrahydroxyldiphenyl.
• an aluminum printing form thus obtained be development with liquid shows a blurred image, owing to bleeding of the azo-dyestuff during development. Also, the selective receptivity to ink and the adherence of the image to the plate are insufficient.
• British Pat. No. l 064 128 describes a process making use of a so-called photographic baryta paper, the coating of which contains barium sulfate as a pigment and a protein binding agent and is sensitized with a light-sensitive diazonium salt of high coupling activity.
• a so-called photographic baryta paper the coating of which contains barium sulfate as a pigment and a protein binding agent and is sensitized with a light-sensitive diazonium salt of high coupling activity.
• development is effected with an alkaline aqueous phloroglucinol solution and the image-bearing surface is subsequently treated with an acid solution of a hydrophilic organic binding agent, in order to render the background areas of the image sufficiently hydrophilic.
• This plate has too porous asurface, and the alkaline phloroglucinol solution has poor keeping quality.
• British Pat. Nos. 1 038 279 and l 082 889 describe processes for making printing forms, in which a paper planographic plate sensitized for direct imaging with a benzene diazonium salt of high coupling activity is imagewise exposed and subsequently developed by means of an aqueous buffered neutral or slightly acid phloroglucinol solution.
• Fairly good printing forms can be obtained from the plates there disclosed.
• These plates have a disadvantage in that the planographic coating, which contains barium sulfate as a pigment and a water-insolubilized protein as a binding agent, is too porous, as a result of which the diazo compound locally penetrates too deeply and, consequently, it is difficult to effect complete bleaching out and coupling of the diazo compound.
• the part of the diazo compound that penetrated too deeply may still form an oleophilic azodyestuff, but since this azo-dyestuff is not present on the surface it does not influence the oleophilic properties of the surface.
• spots which are more or less hydrophilic appear in the oleophilic image areas and manifest themselves as white dots in the image of the prints.
• the too deep penetration that occurs has highly undesirable effects.
• a planographic printing plate fulfilling that need is provided by forming on a suitable paper support a planographic coating consisting essentially of an inorganic filler, or pigment, and a water-insolubilized organic hydrophilic binding agent that is principally a water-'insolubilized polyvinyl alcohol having a degree of hydrolysis greater than 98 percent, and sensitizing this coating with a light-sensitive benzene diazonium salt.
• the plate so produced by being imagewise exposed and subsequently developed with an aqueous buffered phloroglucinol solution having a pH between 4 and 8, is converted into a durable, positive-working planographic, or offset, printing form that will give a large number of desirable clear prints in use.
• the use of the water-insolubilized polyvinyl alcohol in the planographic coating makes it possible to obtain a valuable single-coated paperbased printing plate sensitized with a benzene diazonium salt.
• the single planographic layer coated onto the support adheres sufficiently to the paper surface without need for an intermediate adhesive coating; it can be sensitized without too deep a penetration of the diazo compound; and it has sufficient affinity for the azo-dyestuff to enable a run of at least 50-200 prints from the printing form produced from the plate.
• finely divided inorganic substances such as titanium dioxide, diatomaceous earth and Lustra" clay can be used, either individually or in mixtures with one another or with other pigments.
• the pigment is ordinarily to be made into an aqueous dispersion which in turn is mixed with a solution of the binding agent to obtain a dispersion to be coated onto the paper support.
• water glass a silica so], an alumina sol or a stannic anhydride so], or a mixture of two or more of these, to the pigment dispersion.
• the polyvinyl alcohol to be used as a binding agent for the coating has a degree of hydrolysis greater than 98 percent.
• the binder can be rendered water-insoluble by simply drying the coating containing it in the presence of a cross-linking agent selected from among those known to be suitable for making the polyvinyl alcohol water-insoluble. Good results can be obtained with glyoxal, for instance.
• the planographic coating should be hardened in such a way that it retains only a small water-absorbing capacity. Its waterabsorbing capacity can be determined satisfactorily by use of the so-called Cobb test (See: Tappi Standards T 441 os-69, or British Standard PBMA Test Method PTlS). It has been determined that the value of its water-absorbing capacity as measured according to the Cobb test should amount to less than 6. For most of the known direct imaging plates the corresponding value is considerably higher, amounting to about -20.
• the planographic coating according to the invention differs distinctively from the planographic coatings made with another binding agent such as oxidized starch, hydroxyethyl cullulose, carboxymethyl cellulose, hydroxyethy carboxymethyl cellulose or alginic acid.
• the planographic coating according to the invention preferably is applied so as to have a weight of 9-12 g./m. It is ordinarily advantageous to make it with the filler and the binding agent present in a weight ratio of between 4 and 6 parts of filler to 1 part of binding agent.
• the coating can be applied directly onto any paper having a sufficiently smooth surface, such as super-calendered paper.
• Sensitizing of the planographic coating is preferably effected with an aqueous solution of a light-sensitive benzene diazonium salt. Since the developer to be used is a phloroglucinol solution have a pH between 4 and 8, the diazonium salt must have a relatively high coupling activity. Diazo compounds having a higher coupling activity in an aqueous solution than p-diazo o-chloro-N,N-diethyl aniline are suitable. The coupling activity can be measured in the way described in British Pat. No. 957 836. British Pat. Nos. l 064 128, l 064 129 and 347 430 and the Dutch Pat. Applications Nos. 6508566, 6708503 and 6610037 describe light-sensitive benzene diazonium salts which have a suitably high coupling activity and which can also be used with good results in sensitizing the planographic coating on account of their other properties.
• Auxiliary agents can be used in the sensitizing liquid in order to improve the properties of the light-sensitive coating.
• the acids known to serve as stabilizers for the light-sensitive coating such as phosphoric acid, boric acid and tartaric acid, are particularly useful.
• An unexpectedly good stabilization is obtained with a mixture of boric acid and tartaric acid, in which the boric acid predominates.
• aqueous buffered solution of phloroglucinol having a pH between 4 and 8.
• the buffering of this solution can be effected by the use of buffer salts known to be useful in diazotype developers. These generally are alkaline-reacting salts of weak acids. For instance, good results can be obtained with alkali metal, ammonium or alkaline earth metal tartrates, adipates, acetates, phosphates and citrates as buffers.
• the imagewise exposure is preferably effected by exposing the light-sensitive printing plate, in contact with a transparent original, to actinic light.
• Printing forms achieving a run of to 250 prints can be obtained even from originals obtained by typewriting on translucent paper.
• the original used is produced by typewriting on a translucent sheet having good light-permeability, for instance, on a coated sheet the support of which is a thin polyester or cellulose acetate film and the coating of which consists principally of an inorganic transparent pigment such as amorphous or crystalline silica and a hydrophobic organic film-forming binding agent such as polyvinyl acetate or cellulose acetate-butyrate, some thousands of copies can be made from the printing form obtained, if the weight ratio between pigment and binding agent is greater than 0.8. This ratio is preferably between 1 and 3.
• the coating is applied with sufficient thickness that it weighs 12 g./m. upon being dried and hardened by heating it for to sec. at 155 to 160 C.
• a plate prepared as above described in this Example 1 is sensitized with each of the sensitizing liquids, so that each plate contains about 0.5 millimol of diazo compound per m after drying.
• the sensitized plates are marked a, b, c and d, respectively.
• the light-sensitive printing plates are imagewise exposed under a translucent paper original provided with a strongly UV-absorbing typewritten text, until all the diazo compound has bleached out under the imagefree areas of the original. Subsequently each plate is developed with a solution which contains:
• the pH of this solution is about 6.5.
• Plate a has a run of 150, plate b of 200, plate c of 100 and plate d of 250 good prints.
• 600 ml. of polyvinyl alcohol solution has been replaced by 600 ml. of a solution containing 100 g. of sodium carboxy-methyl cellulose in 1,000 ml. of water.
• 600 ml. of polyvinyl alcohol solution has been replaced by 600 ml. of a solution containing 66 g. of hydroxyethyl cellulose in 1,000 ml. of water.
• the plates are imagewise exposed and subsequently developed with a solution containing:
• Printing is effected by an offset printer from the six printing forms obtained. Only the printing form of plate a will give a good result.
• Each of the three printing forms thus produced gives a run of about 200 prints.
• a sensitized plate for conversion into a planographic printing form comprising a paper support carrying thereon a planographic coating consisting essentially of a layer of a water-insolubilized hydrophilic organic binder having a finely divided inorganic filler dispersed therein and a light-sensitive diazo compound applied to said layer, wherein said binder consists principally of a substantially water-insoluble product of the cross-linking, in situ in said layer to such extent that the water-absorbing capacity of said layer is less than about 6 as measured by the Cobb test, of polyvinyl alcohol having a degree of hydrolysis greater than 98 percent in admixture with a cross-linking agent for said polyvinyl alcohol and said diazo compound is a non-polymeric benzene diazonium salt that has a higher coupling activity in aqueous solution than p-diazo-ochloro-N,N-dimethyl aniline and that forms an ink-receptive azo dyestuff by coupling with
• a sensitized plate according to claim 1 said layer containing, by weight, 4-6 parts of said filler to 1 part of said binder.
• a sensitized plate according to claim 1 said layer being adhered by said binder directly to the paper surface of said support.
• a sensitized plate according to claim 1 said layer having said diazonium salt applied thereto in admixture with an acidic stabilizer comprising a mixture of boric acid and tartric acid in which the boric acid predominates.
• a sensitized plate according to claim 1 said cross-linking agent comprising glyoxal provided initially in said layer in admixture with said polyvinyl alcohol.
• a sensitized plate according to claim 1 said salt being a benzoylamino-dibutoxy-benzene diazonium salt, a phenylthiobenzene diazonium salt or a bis-(acetoxy-ethyl) aminochlorophenoxy-chloro-benzene diazonium salt.
• a sensitized plate according to claim 1 said salt being a dimethylamino-chloro-(4' methyl-phenyl)thio-benzene diazonium salt.
• a sensitized plate according to claim 1 said filler consist ing principally of pigmentary titanium dioxide, diatomaceous earth or clay or a mixture thereof.
• a sensitized plate according to claim 1 said filler consisting principally of pigmentary titanium dioxide diatomaceous earth or clay or a mixture thereof in admixture with a minor proportion of alumina, silica, water glass or stannic anhydride or a mixture thereof.
• a sensitized plate for conversion into a planographic printing form comprising a paper support carrying thereon a planographic coating consisting essentially of a layer of a water-insolubilized hydrophilic organic binder having a finely divided inorganic filler dispersed therein and a light-sensitive diazo compound applied to said layer in admixture with an acidic stabilizer, said layer containing, by weight, about 4-6 parts of said filler to 1 part of said binder and being adhered by said binder directly to the paper surface of said support, said binder consisting principally of a substantially water-insoluble product of the cross-linking, in situ in said layer, of polyvinyl alcohol having a degree of hydrolysis greater than 98 percent in admixture with glyoxal as a cross-linking agent other than said polyvinyl alcohol itself, said diazo compound being a phenylthio-benzene diazonium salt that has a higher coupling activity in aqueous solution than p-diazo
• a sensitized plate according to claim 10 said polyvinyl alcohol having been cross-linked to such extent that the waterabsorbing capacity of said layer is less than about 6 as measured by the Cobb test.
• a sensitized plate according to claim 10 said diazo compound being a dimethylamino-chloro-(4' methylphenyl)thio-benzene diazonium salt.
• a sensitized plate according to claim 10 said filler consisting of principally of pigmentary titanium dioxide, diatomaceous earth or clay or a mixture thereof in admixture with a minor proportion of alumina, silica, water glass or stannic anhydride or a mixture thereof.
• a planographic printing form comprising a paper support carrying thereon a planographic coating consisting essentially of a layer of a water-insolubilized hydrophilic organic binder having a finely divided inorganic filler dispersed therein and an image of an oleophilic azo-dyestuff formed on said layer, wherein said binder consists principally of a substantially water-insoluble product of the cross-linking, in situ in said layer, of polyvinyl alcohol having a degree of hydrolysis greater than 98 percent in admixture with glyoxal as a crosslinking agent and said dyestuff is a reaction product of a nonpolymeric benzene diazonium salt applied to said layer, said salt having a higher coupling activity in aqueous solution than p-diazo-o-chloro-N,N-dimethyl aniline, and phloroglucinol.

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• Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Molecular Biology (AREA)
• General Physics & Mathematics (AREA)
• Printing Plates And Materials Therefor (AREA)
• Photosensitive Polymer And Photoresist Processing (AREA)
• Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)

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Cited By (7)

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Citations (7)

• 1968
  • 1968-01-12 NL NL6800539A patent/NL6800539A/xx unknown
  • 1968-12-31 FR FR1601951D patent/FR1601951A/fr not_active Expired
• 1969
  • 1969-01-07 DE DE19691900469 patent/DE1900469A1/de active Pending
  • 1969-01-07 NO NO00058/69A patent/NO127472B/no unknown
  • 1969-01-09 US US790174A patent/US3658538A/en not_active Expired - Lifetime
  • 1969-01-09 BE BE726643D patent/BE726643A/xx unknown
  • 1969-01-09 GB GB0348/69A patent/GB1249382A/en not_active Expired
  • 1969-01-10 AT AT22469A patent/AT288445B/de not_active IP Right Cessation
  • 1969-01-10 DK DK15869AA patent/DK125496B/da unknown
  • 1969-01-10 SE SE00289/69A patent/SE352750B/xx unknown
  • 1969-01-13 CH CH43769A patent/CH510898A/de not_active IP Right Cessation

Patent Citations (7)

Non-Patent Citations (1)

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