CA1046865A - Process for the preparation of printing forms - Google Patents
Process for the preparation of printing formsInfo
- Publication number
- CA1046865A CA1046865A CA198,310A CA198310A CA1046865A CA 1046865 A CA1046865 A CA 1046865A CA 198310 A CA198310 A CA 198310A CA 1046865 A CA1046865 A CA 1046865A
- Authority
- CA
- Canada
- Prior art keywords
- image
- finely divided
- developer
- process according
- layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G13/00—Electrographic processes using a charge pattern
- G03G13/26—Electrographic processes using a charge pattern for the production of printing plates for non-xerographic printing processes
- G03G13/32—Relief printing plates
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G13/00—Electrographic processes using a charge pattern
- G03G13/26—Electrographic processes using a charge pattern for the production of printing plates for non-xerographic printing processes
- G03G13/28—Planographic printing plates
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
Abstract
Abstract of the Disclosure This invention relates to an improvement in the process for the preparation of printing forms or metallic etchings from electro-photographic or electrographic reproduction materials composed of a support with a photoconductive or high-ohmic layer thereon, by charging and image-wise exposure, or by image-wise charging, development of the electrostatic image with a finely-divided toner, fixing, and removal of the layer in the image-free areas by means of a decoating solution, the improvement comprising developing the electrostatic image with a developer which renders the image areas hydrophobic at room temperature, and simultaneously effects develop-ment and resistance to the decoating solution.
Description
PROCESS FOR THE PREPARATION OF P~INTING FORMS
This invention relates to the preparation of printing forms or metallic etchings from electrophotographic or electrographic reproduc~
tion material composed of a support with a photoconductive or high-ohmic layer thereon, by charging and image-wise exposure of the material, or by image-wise charging of the material, followed by de-velopment of the electrostatic image with a finely divided toner, fix-lng, removal of the layer in the image-free areas by means of a decoat-ing solution, and, optionally, etching of the bared areas of the support.
Processes for the preparation of printing forms by electrophoto-- graphic means are known. In German Patent No. 974,162, for example, a process is described for the preparation of lithographic printing plates from coated papers, in which the surface of an electroconduc-tive, moisture~resistant paper foil is coated with a layer composed of a photoconductor substance suspended in a dielectric, film-forming carrier substance, the layer ls electrostatically charged, image-wlse exposed, and then developed with a powder which accepts greasy ink.
Subsequently, the non-printing areas of the printlng plate are rendered hydrophilic. For this purpose, the powder is either fixed to the photo-conductlve layer in such a manner, by heat action, that it substantially fuses through the photoconductive layer, or it is forced into the photo-conductive layer, or the powder image is provided with a thin film of a material serving as a solvent for the powder image or for the photo-conductive layer in order to provide satisfactory adhesion. The sol-vent is then removed by heating. Subsequently, the non-image areas are converted into a hydrophilic material by an impregnation step which should not affect the fixed powder image. If the photoconductive layer is coated on top of a hydrophilic layer, or if the photoconductive layer /
,`
~
is composed of a substance which is easily removed, the photoconduc-tive coating may also be removed from the non-image areas.
A process of this type can be used only for paper printing plates which are known to yield only short runs, and lithographic copies of poor quality. Moreover, the powder image must be anchored by heat fixation, pressure or solvents must be applied, and further heat is possibly required, so that the process is also less advantageous as regards expendlture in time and equipment.
It is also known from German Auslegeschrift No. 1,117,391, -I0 to use photoconductive organic compounds in the layers of electro-photographic reproduction materials from which printing forms are ~;
produced. The materials have a support which is suitable for printing purposes. The photoconductive layer is composed of a mono-molecular photoconductor and hlgh molecular welght alkali-soluble substances.
The material is charged and exposed in the conventional manner and developed with a colored resin powder. The resin powder ls fixed by heating the materlal to a temperature between 100 and 250C, and the layer is then treated with an alkaline solutlon, so that the non-lmage areas are d-ssolved away and a planographic printing plate - -results. Although foils of metal, paper, or plastlc materials are suggested for this process, a dimenslonally accurate reproductlon ls not guaranteed, because a thermal fixlng process always lnvolves the risk of a dimensional alteration. Moreover, the expenditure on equip-ment necessary for performing the thermal flxing process always lm-pedes the automation of a process for the preparation of printing plates.
Thus, it is the object of the present invention to provide a process for the preparation of printing forms which may be performed at a relatively low temperature, preferably at room temperature, and : . ' : ' . - ' does not require an additional fixing step. Accordingly the invention pro-vides in a process for the preparation of printing forms or metallic etchings from electrographic or electrophotographic reproduction materials composed of a support with a high-ohmic resin layer or a layer containing an organic photoconductive material in a resin binder thereon by image-wise charging or by charging and image-wise exposure, development of the electrostatic image with a finely divided toner, fixing, and removal of the layer in the image-free areas by means of a decoating solution, the improvement which comprises developing and fixing the electrostatic image on said layer by treating it with a developer composed of a high-ohmic liquid phase and a fine-ly divided solid phase therein which solid phase is at least one high mole-cular weight product selected from the group consisting of the high-vacuum bitumen, wax and resin type, which renders the image areas hydrophobic at ; room temperature, and simultaneously effects development and resistance to the decoating solution.
As an optional step, the re val of the layer in the image-free areas by means of the decoating solution may be followed by etching of the bared surface of the support.
The composition of the developer material to be used depends also upon the composition of the decoating solution employed for removing the copying layer from the non-image areas.
; It is achieved by the present invention that the additional fixing step, i.e. the heating or burning-in of the material within a sub-stantially constant, controllable temperature range, can be completely omitted, providing a process for the preparation of printing ~orms which can be easily and economically applied to any type of appropriate support.
If metallized plastic films are used, for example, decoating and etching away of the metal layer in the non-image areas produces '',`
~ ! f ~
, ,~, ~~ K-2228 ~046865 transparent images whose image areas are distinguished by a very high optical density. Moreover, the images produced on the film bases are true to scale. Altogether, the inventive process provides a consider-able saving in time and apparatus, which is of decisive importance with aviewto the automation of the entire process.
By the process of the present invention, printing forms for planographic prlnting, gravure printing, letterpress printing, and screen printing, as well as printed circuits, may be produced by electrophotographic or electrographic methods.
The electrophotographic printing form used as the starting ma-terial for the process of the invention is known in principle. The use of photoconductive organic substances in electrophotographic layers and the conversion of these layers into printing forms is known, for - ~-example from the publications mentioned above for defining the pres- ~-ent state of the art~ Photoconductors containing one or more dialkyl amlno groups may be used with particular advantage for the present lnvention. Particular mention is made of heterocyclic compounds, such as the oxadiazole derivatives Icnown from German Patent No.
1, 058, 836, especially the 2, 5-bis- (4'-diethylaminophenyl)-oxadiazole-1,3,4. Other suitable photoconductors are, for example, triphenyl-amine derivatives, highly condensed aromatic compounds, such as anthracene, benzo-condensed heterocyclic compounds, pyrazoline derivatives, and imidazole derivatives. The triazole and oxazole derivatives disclosed in German Patents Nos . 1, 060, 260, and 1,120,875, also may be used. Further, vinyl-aromatic polymers, such as polyvinyl anthracene, polyacenaphthylene, and polyvinyl carbazole, and the copolymers of these compounds, are also suitable, provided they are capable of a differentiation in solubility character-istics, if necessary in combination with a resin binder. Other suitable compounds are the polycondensates of aromatic amines and aldehydes described in German Auslegeschrift No. 1,197,325.
In addition to the compounds just mentioned, which prepon-derantly are of p-conductive nature, n-conductive compounds also may be used. These so-called electron acceptors are known, e.g., from German Patent No. 1,`127,218.
As regards film-forming characteristics and adhesion, both natural and synthetic resins are suitable as resin binders. In addition to their film-forming and electrical characteristics and their adhesion to the support, the solubility characteristics of the resins are of particular importance. Resin binders which are soluble in aqueous or alcoholic solvent systems, to which, if desired, an acid or an alkaline substance may be added, are particularly suitable for practi-cal purposes. For physiological and safety reasons, readily flamm-able aromatic or aliphatic solvents are ruled out. Therefore, the preferred resin binders are high molecular weight substances contain-ing groups which render them alkali-soluble, such as acid anhydride groups, carboxyl groups, phenol groups, sulfonic acid groups, sulfon-amide groups, or sulfonimide groups. Resin binders having high acid numbers are preferred because they are particularly readily soluble in alkaline-aqueous-alcoholic solvent systems. Copolymers containing anhydride groups may be used with particular advantage because, due to the absence of free acid groups, the conductivity of the electro-photographic layer in the dark is low, in spite of its good solubility in alkaline solutions.
Copolymers of styrene and maleic anhydride, such as those ~3 ' known by the name of " Lytron" (products of Monsanto Chemical Com-pany, St. Louis, Mo., USA), andphenolresins, suchasthoseknown ~A~
by the name of "Alnovol'r~ (products of Chemische Werke Albert, Wiesbaden-Biebrich, Germany) have proved to be particularly suit-able.
Further, the copying layer of the electrophotographic printing form used as the starting material may contain ~cnown sensitizers .
Only small quantities of sensitizer are added to the copying layer, i.e. about 0.001% to about 1%, calculated on the weight of the photo-conductor component. Suitable sensitizers, most of them dyestuffs, are known, for example, from Belgian Patent No. 558,078.
If electrographic layers are used, the same resin binders as described in connection with the electrophotographic layers may be employed. The layers must meet the same requirements as the photo-conductive layers, except that the photoconductor component is omitted.
Any of the known materials suitable for this purpose, e.g.
alumlnum, zinc, magnesium, chromium, or copper plates, may be used as the support of the electrophotographic or electrographic printing plate employed as the starting material, and their surfaces may be pre-treated, if desired. Cellulose products, such as cellulose hy-drate, cellulose acetate, or cellulose butyrate films, or paper that has been superficially hydrophilized and made electrically conductive, as well as plastic films and compound materials composed of paper or plastic film and metal layers, also may be used. Supports com-posed of layers of different metals are also suitable.
For the preparation of metallic etchings, metallized plastic materials in the form of films or plates are used as supports, the metal layer being applied by vapor deposition, lamination, or by chemical or galvanic metal deposition.
~A -6-Developers which are suitable for the present invention are hydrophobic substances which are not easily wetted by the decoating solution, for example, high molecular weight natural or synthetic waxes and resins. The developer substances must, as far as possible, dlstinguish in their solubility characteristics from the copying layer.
They must not easily dissolve in the decoating solutions used for re-moving the copying layer in the non-image areas. Further, they must have a good adhesion to the reproduction layer and provlde a good coverage for the image areas. Compounds of the group of bitumen, waxes, and resins have proved to be particularly suitable, for example, synthetic ester waxes with saponification values between 130 and 150 and drop points between about 75 and 90 C, hard paraffin with a soft-enlng range between about 50 and 70C, carnauba wax, colophony, or shellac. High~vacuum bitumen with a softening range between about 130 and 150 C has proved to be particularly suitable.
The aforementioned substances may be used either in a dry de-velopment process, or they may be applied as developer dlspersions, in a liquid developing process. A liquid developing process is preferr-ed, uslng a developer composed of a high-ohmic liquid phase with a ~20 finely-divided solid phase dispersed therein. Liquid development has proved to be particularly advantageous because the developing process ls clean and free from dust and the copies produced are distinguished by a very good photographic dissolution.
The liquid developer is composed of a dispersion medium, the developer component, and additives which assist the dispersion of the components and influence the electrical charge of the developer.
The preparation and use of suitable additives is described in German Auslegeschrift No . 1, 047, 616 .
Suitable dispersion media are those liquids which do not dis-solve the solid phases at room temperature. A number of halogenated hydrocarbons have proved to be advantageous, but, above all, liquid aliphatic hydrocarbons, for example an isoparaffin with a boiling range between 185 and 210C. The polarity of the charge of the dispersed phase depends upon the properties of the dispersed substance itself as well as upon the selected dispersion medium.
Wax-based developer dispersions are advantageously prepared by dlssolving the developer substance in the hot dispersion medium and then chilling the solution to room temperature, an excellently sultable flnely-divided wax dispersion belng the result.
The developer may be applled in known manner. In the case of a liquld developer, the developer may be applied by immersion or by roller application, the latter method being preferred for an automatic process .
After development of the latent electrostatic Image, the devel-oper substance adheres to the copying layer in the form of the image, Appllcatlon of the decoating solution follows.
The decoating solution is distributed over the layer, e.g., by wiping with a cotton pad. Alternatively, the plates may be immersed ln the decoating solution. As a preferred method, the decoating solu-tion ls sprayed upon the layer. Suitably constructed apparatuses also may be used for decoating, e.g., application roll systems. In this manner, the differentiation between hydrophilic and oleophllic areas necessary for offset printing is produced, the image areas represent-ing the oleophilic areas of the printing plate.
The composition of suitable decoating solutions is known, for example, from German Patent No. 1,117,391. Decoating solutions , .
,:
which have proved to be particularly suitable for the inventive process are mixtures of alcohols containing sodium metasilicate or ethanol-amine as the alkaline component. A 5% by weight aqueous solution of phosphoric acid has proved to be suitable as an acid decoating solution .
After treatment with the decoating solution, the printing form is advantageously rinsed with water; if desired, its hydrophobic properties may be further increased by wiping with dilute phosphoric acid solution, After inking with greasy ink, printing may be performed -ln known manner in a planographic printing machine (offset printing).
Alternatlvely, printing forms for letterpress, or, if desired, for gravure prlnting may be produced by the subsequent dissolution of the bared supporting material.
Dissolution may be performed in known one-bite or multi-stage etching machines used for this purpose. If a multi-metal material is used as the support, etching is performed by conventional photoengraving methods. The printing plates obtained by the present process are capable of very long runs.
By the process of the present invention, printing forms and printed circuits may be produced; further, it may be used ln the X-ray and microfilm field.
The lnvention will be further illustrated by reference to the following specific examples:
ExamPle 1 A solution containing 10 g of 2-vinyl-4-(2'-chlorophenyl)-5-(4"-diethyl-aminophenyl)-oxazole, 10 g of a styrene/malèic anhy-dride copolymer with a softening point of 210C, and 20 mg of "Rhodamine FB" in a mixture of 235 ml of glycol monomethyl ether ._ 9 _ .
and 65 ml of butyl acetate is applied to an about lOOp thick, superfici-ally roughened aluminum foil. After evaporation of the solvent, the resulting- photoconductor layer is charged by means of a corona to be negative potential of about 400 volts and exposed under a negative transparency in a re-enlargement apparatus.
At stop 8 and using a 100 watt incandescent lamp as the light source, the exposure time is 30 seconds for an enlargement scale of 1: 5. The latent image is developed with a toner liquid prepared by finely dispersing 1 g of a synthetic ester wax having a saponification value of 130 - 150 and a drop point between 81 and 86 C in a solu-tion of 2 g of a pentaerythritol resin ester as a dispersing agent (e.g. "Pentalyn H" ~), a product of Hercules Powder Company, i-Wilmington, Delaware, USA) in 20 ml of isoparaffin and diluting the resulting dispersion with 1,000 ml of an isoparaffin having a boiling range between 185 and 210C. 0.5 g of soya lecithin is added to the developer liquid as a charge control agent.
The developed plate is converted into a printing form by immersing it for 1 minute in a solution of 35 g of sodium metasilicate hydrate in a mixture of 140 ml of glycerol, 550 ml of ethylene glycol, and 140 ml of ethanol, and then rinsing it with a water ~et while brushing gently. A positive printing form is thus obtained from the negative microfilm original.
Exam~le 2 The procedure described in Example 1 is repeated, except that the synthetic ester wax used in Example 1 as the developer substance is replaced by a phenol resin. The developer is prepared by finely dispersing, in a ball mill, 1 g of a phenol-formaldehyde resin with a , - 10-10468{j5 K-22 2 8 melting point of 75 - 83 C in a solution of 1.5 g of a pentaerythritol resin ester in 70 ml of an isoparaffin, diluting the resuLting dispersion with 1,000 ml of an isoparaffin with a boiling range of 185 - 210C, and adding 0.2 g of soya lecithin as a charge control agent.
Example 3 A solution of 15 g of a condensation product of N-ethylaniline and formaldehyde, 0.41 g of dibromo-succinic acid, and 0.15 g of "Rhodamine FB" in a mixture of 40 ml of toluene, 20 ml of trichloro-ethylene, and 25 ml of methanol is coated upon a mechanically rough-ened aluminum foil. After evaporation of the solvents, a photoconduc-tor layer is obtalned which is charged in the dark, to a negative potential of 350 volts, by means of a coron~. The charged foil is then exposed for approximately 2 minutes in a camera and developed with a toner liquid which protects the image areas from the effect of the de-coating solution by rendering them hydrophobic. The toner liquid is prepared by finely dispersing 1 g of a hard paraffin with a softening range between 50 and 62 C in a solution of 2 g of a pentaerythritol resin ester in 20 ml of an isoparaffin and diluting the resulting disper-slon wlth 1,000 ml of an isoparaffin having a boiling range between 185 and 210C. The developed plate is then bathed for about 2 mlnutes in 5% by weight aqueous phosphoric acid solution, and the dissolved photoconductor substance present in the image-free areas is rinsed off with water.
Example 4 A solution containing 10 g of 2,5-bis-(4'-diethylaminophenyl)-1,3,4-oxadiazole, 10 g of a styrene/maleic anhydride copolymer with a softening point of 210C, and 20 mg of "Rhodamine FB" in 300 ml of glycol monomethyl ether is applied to an about lOOp thick polyester , foil carrying a vacuum-deposited aluminum layer. The coated foil is charged to a negative potential of about 400 volts by means of a corona and is then exposed for 3 seconds, in contact with a transparent film original, to the light of a 100 watt incandescent lamp from a dis-tance of 65 cm. The exposed foil is developed with a developer liquid pre-pared by dissolving or dispersing 1.5 g of a high-vacuum bitumen with a softening range from 130 to 140C ("Bitumen D 130-140 HVB", a product of Shell AG, Hamburg, Germany) and 6.5 g of a pentaerythritol resin ester in 1,000 ml of an isoparaffin with a boiling range between 185 and 210C. In the areas not covered by the bitumen developer, - -the photoconductor layer is removed with a sodium metasilicate solu-tion as described in Example 1. In order to dissolve the about 1~
thick alumlnum layer in the image-free areas, the foil is bathed in 2N
caustlc soda solution. A positive transparency of the original is thus produced which has a very good covering power.
ExamPle 5 Equally good resùlts are obtained by using a chemically nickel-plated polvester film instead of the foil with the vacuum-deposited aluminum layer. In order to remove the nickel layer after the production of the image, a commercial nickel etching solution is used .
Example 6 The photoconductive material described in Example 1 and com-posed of an alumlnum foil with a photoconductor layer thereon is used.
The foil is charged in the dark to a negative potential of 400 volts by means of a corona and is then exposed for approximately 20 seconds in a camera. The latent charge image thus produced on the foil is then developed in a dispersion of 1 g of colophony in a solution of 2 g of a -- ~ K-2228 - 1~46865 pentaerythritol resin ester in 1,000 ml of an isoparaffin with a boiling range between 185 and 210C to which 0.2 g of zirconyl linoleate is added as a charge control agent.
The developed plate is converted into a printing form as de-scribed in Example 1.
Example 7 An alumlnum foil coated with a photoconductor layer as de-scribed ln Example 1 ls charged to a negative potential of 400 volts by means of a corona and exposed in contact with a positive trans-parency (transparent original). The exposure time is 3 seconds, using a 100 watt incandescent lamp at a dlstance of 65 cm. The latent charge image thus produced is developed with a developer liquid pre-pared by finely dispersing 0.3 g of a bleached, white, wax-free shellac powder with a melting point of 63 C in a solution of 0 . 4 g of a pentaerythrltol resin ester ln 1, 000 ml of an isoparaffin with a boil-ing range of 185 - 210C. 3 ml of a 6% by weight solution of zlrconyl linoleate are added to the developer liquid as a charge control agent.
The developed plate is converted into a printing form inthe manner described in Example 1, by removal of the image-free areas with a sodium metasilicate solution.
Example 8 The method described in Example 7 is repeated, except that the developer liquid used for developing the latent charge image is re-placed by a dry developer. For this purpose, 6 g of a bleached, white, wax-free shellac powder with a melting point of 63 C are mixed with 100 g of iron powder having a grain size between 75 and 150~. The mixture is applied to the plate in the manner normally used ln electrophotographic processes, i.e. by means of a magnetic brush.
After development of the latent charge image, the plate is immersed in a decoating solution, as described in Example 1, and thus con-verted into a printing form.
Example 9 A solution of 6 9 of a styrene/maleic anhydride copolymer with a softenlng point of 210C in a mixture of 74 ml of glycol mono-methyl ether and 20 ml of butyl acetate is mechanically applied to a superficially roughened aluminum foil having a thickness of 100 ~
After evaporation of the solvent, the coated foil is charged by means of a corona, using an image-wise blanked-out aluminum foil as a -stencil. The charged image areas have a negative potential of 300 volts. The charge image thus produced is then developed with a toner liquld prepared by dispersing 0 . 5 g of carnauba wax in a solution of l g of a pentaerythrltol resin ester in lO ml of an isoparaffin and diluting the resulting dlsperslon with a solution of 0 . 3 g of zirconyl-
This invention relates to the preparation of printing forms or metallic etchings from electrophotographic or electrographic reproduc~
tion material composed of a support with a photoconductive or high-ohmic layer thereon, by charging and image-wise exposure of the material, or by image-wise charging of the material, followed by de-velopment of the electrostatic image with a finely divided toner, fix-lng, removal of the layer in the image-free areas by means of a decoat-ing solution, and, optionally, etching of the bared areas of the support.
Processes for the preparation of printing forms by electrophoto-- graphic means are known. In German Patent No. 974,162, for example, a process is described for the preparation of lithographic printing plates from coated papers, in which the surface of an electroconduc-tive, moisture~resistant paper foil is coated with a layer composed of a photoconductor substance suspended in a dielectric, film-forming carrier substance, the layer ls electrostatically charged, image-wlse exposed, and then developed with a powder which accepts greasy ink.
Subsequently, the non-printing areas of the printlng plate are rendered hydrophilic. For this purpose, the powder is either fixed to the photo-conductlve layer in such a manner, by heat action, that it substantially fuses through the photoconductive layer, or it is forced into the photo-conductive layer, or the powder image is provided with a thin film of a material serving as a solvent for the powder image or for the photo-conductive layer in order to provide satisfactory adhesion. The sol-vent is then removed by heating. Subsequently, the non-image areas are converted into a hydrophilic material by an impregnation step which should not affect the fixed powder image. If the photoconductive layer is coated on top of a hydrophilic layer, or if the photoconductive layer /
,`
~
is composed of a substance which is easily removed, the photoconduc-tive coating may also be removed from the non-image areas.
A process of this type can be used only for paper printing plates which are known to yield only short runs, and lithographic copies of poor quality. Moreover, the powder image must be anchored by heat fixation, pressure or solvents must be applied, and further heat is possibly required, so that the process is also less advantageous as regards expendlture in time and equipment.
It is also known from German Auslegeschrift No. 1,117,391, -I0 to use photoconductive organic compounds in the layers of electro-photographic reproduction materials from which printing forms are ~;
produced. The materials have a support which is suitable for printing purposes. The photoconductive layer is composed of a mono-molecular photoconductor and hlgh molecular welght alkali-soluble substances.
The material is charged and exposed in the conventional manner and developed with a colored resin powder. The resin powder ls fixed by heating the materlal to a temperature between 100 and 250C, and the layer is then treated with an alkaline solutlon, so that the non-lmage areas are d-ssolved away and a planographic printing plate - -results. Although foils of metal, paper, or plastlc materials are suggested for this process, a dimenslonally accurate reproductlon ls not guaranteed, because a thermal fixlng process always lnvolves the risk of a dimensional alteration. Moreover, the expenditure on equip-ment necessary for performing the thermal flxing process always lm-pedes the automation of a process for the preparation of printing plates.
Thus, it is the object of the present invention to provide a process for the preparation of printing forms which may be performed at a relatively low temperature, preferably at room temperature, and : . ' : ' . - ' does not require an additional fixing step. Accordingly the invention pro-vides in a process for the preparation of printing forms or metallic etchings from electrographic or electrophotographic reproduction materials composed of a support with a high-ohmic resin layer or a layer containing an organic photoconductive material in a resin binder thereon by image-wise charging or by charging and image-wise exposure, development of the electrostatic image with a finely divided toner, fixing, and removal of the layer in the image-free areas by means of a decoating solution, the improvement which comprises developing and fixing the electrostatic image on said layer by treating it with a developer composed of a high-ohmic liquid phase and a fine-ly divided solid phase therein which solid phase is at least one high mole-cular weight product selected from the group consisting of the high-vacuum bitumen, wax and resin type, which renders the image areas hydrophobic at ; room temperature, and simultaneously effects development and resistance to the decoating solution.
As an optional step, the re val of the layer in the image-free areas by means of the decoating solution may be followed by etching of the bared surface of the support.
The composition of the developer material to be used depends also upon the composition of the decoating solution employed for removing the copying layer from the non-image areas.
; It is achieved by the present invention that the additional fixing step, i.e. the heating or burning-in of the material within a sub-stantially constant, controllable temperature range, can be completely omitted, providing a process for the preparation of printing ~orms which can be easily and economically applied to any type of appropriate support.
If metallized plastic films are used, for example, decoating and etching away of the metal layer in the non-image areas produces '',`
~ ! f ~
, ,~, ~~ K-2228 ~046865 transparent images whose image areas are distinguished by a very high optical density. Moreover, the images produced on the film bases are true to scale. Altogether, the inventive process provides a consider-able saving in time and apparatus, which is of decisive importance with aviewto the automation of the entire process.
By the process of the present invention, printing forms for planographic prlnting, gravure printing, letterpress printing, and screen printing, as well as printed circuits, may be produced by electrophotographic or electrographic methods.
The electrophotographic printing form used as the starting ma-terial for the process of the invention is known in principle. The use of photoconductive organic substances in electrophotographic layers and the conversion of these layers into printing forms is known, for - ~-example from the publications mentioned above for defining the pres- ~-ent state of the art~ Photoconductors containing one or more dialkyl amlno groups may be used with particular advantage for the present lnvention. Particular mention is made of heterocyclic compounds, such as the oxadiazole derivatives Icnown from German Patent No.
1, 058, 836, especially the 2, 5-bis- (4'-diethylaminophenyl)-oxadiazole-1,3,4. Other suitable photoconductors are, for example, triphenyl-amine derivatives, highly condensed aromatic compounds, such as anthracene, benzo-condensed heterocyclic compounds, pyrazoline derivatives, and imidazole derivatives. The triazole and oxazole derivatives disclosed in German Patents Nos . 1, 060, 260, and 1,120,875, also may be used. Further, vinyl-aromatic polymers, such as polyvinyl anthracene, polyacenaphthylene, and polyvinyl carbazole, and the copolymers of these compounds, are also suitable, provided they are capable of a differentiation in solubility character-istics, if necessary in combination with a resin binder. Other suitable compounds are the polycondensates of aromatic amines and aldehydes described in German Auslegeschrift No. 1,197,325.
In addition to the compounds just mentioned, which prepon-derantly are of p-conductive nature, n-conductive compounds also may be used. These so-called electron acceptors are known, e.g., from German Patent No. 1,`127,218.
As regards film-forming characteristics and adhesion, both natural and synthetic resins are suitable as resin binders. In addition to their film-forming and electrical characteristics and their adhesion to the support, the solubility characteristics of the resins are of particular importance. Resin binders which are soluble in aqueous or alcoholic solvent systems, to which, if desired, an acid or an alkaline substance may be added, are particularly suitable for practi-cal purposes. For physiological and safety reasons, readily flamm-able aromatic or aliphatic solvents are ruled out. Therefore, the preferred resin binders are high molecular weight substances contain-ing groups which render them alkali-soluble, such as acid anhydride groups, carboxyl groups, phenol groups, sulfonic acid groups, sulfon-amide groups, or sulfonimide groups. Resin binders having high acid numbers are preferred because they are particularly readily soluble in alkaline-aqueous-alcoholic solvent systems. Copolymers containing anhydride groups may be used with particular advantage because, due to the absence of free acid groups, the conductivity of the electro-photographic layer in the dark is low, in spite of its good solubility in alkaline solutions.
Copolymers of styrene and maleic anhydride, such as those ~3 ' known by the name of " Lytron" (products of Monsanto Chemical Com-pany, St. Louis, Mo., USA), andphenolresins, suchasthoseknown ~A~
by the name of "Alnovol'r~ (products of Chemische Werke Albert, Wiesbaden-Biebrich, Germany) have proved to be particularly suit-able.
Further, the copying layer of the electrophotographic printing form used as the starting material may contain ~cnown sensitizers .
Only small quantities of sensitizer are added to the copying layer, i.e. about 0.001% to about 1%, calculated on the weight of the photo-conductor component. Suitable sensitizers, most of them dyestuffs, are known, for example, from Belgian Patent No. 558,078.
If electrographic layers are used, the same resin binders as described in connection with the electrophotographic layers may be employed. The layers must meet the same requirements as the photo-conductive layers, except that the photoconductor component is omitted.
Any of the known materials suitable for this purpose, e.g.
alumlnum, zinc, magnesium, chromium, or copper plates, may be used as the support of the electrophotographic or electrographic printing plate employed as the starting material, and their surfaces may be pre-treated, if desired. Cellulose products, such as cellulose hy-drate, cellulose acetate, or cellulose butyrate films, or paper that has been superficially hydrophilized and made electrically conductive, as well as plastic films and compound materials composed of paper or plastic film and metal layers, also may be used. Supports com-posed of layers of different metals are also suitable.
For the preparation of metallic etchings, metallized plastic materials in the form of films or plates are used as supports, the metal layer being applied by vapor deposition, lamination, or by chemical or galvanic metal deposition.
~A -6-Developers which are suitable for the present invention are hydrophobic substances which are not easily wetted by the decoating solution, for example, high molecular weight natural or synthetic waxes and resins. The developer substances must, as far as possible, dlstinguish in their solubility characteristics from the copying layer.
They must not easily dissolve in the decoating solutions used for re-moving the copying layer in the non-image areas. Further, they must have a good adhesion to the reproduction layer and provlde a good coverage for the image areas. Compounds of the group of bitumen, waxes, and resins have proved to be particularly suitable, for example, synthetic ester waxes with saponification values between 130 and 150 and drop points between about 75 and 90 C, hard paraffin with a soft-enlng range between about 50 and 70C, carnauba wax, colophony, or shellac. High~vacuum bitumen with a softening range between about 130 and 150 C has proved to be particularly suitable.
The aforementioned substances may be used either in a dry de-velopment process, or they may be applied as developer dlspersions, in a liquid developing process. A liquid developing process is preferr-ed, uslng a developer composed of a high-ohmic liquid phase with a ~20 finely-divided solid phase dispersed therein. Liquid development has proved to be particularly advantageous because the developing process ls clean and free from dust and the copies produced are distinguished by a very good photographic dissolution.
The liquid developer is composed of a dispersion medium, the developer component, and additives which assist the dispersion of the components and influence the electrical charge of the developer.
The preparation and use of suitable additives is described in German Auslegeschrift No . 1, 047, 616 .
Suitable dispersion media are those liquids which do not dis-solve the solid phases at room temperature. A number of halogenated hydrocarbons have proved to be advantageous, but, above all, liquid aliphatic hydrocarbons, for example an isoparaffin with a boiling range between 185 and 210C. The polarity of the charge of the dispersed phase depends upon the properties of the dispersed substance itself as well as upon the selected dispersion medium.
Wax-based developer dispersions are advantageously prepared by dlssolving the developer substance in the hot dispersion medium and then chilling the solution to room temperature, an excellently sultable flnely-divided wax dispersion belng the result.
The developer may be applled in known manner. In the case of a liquld developer, the developer may be applied by immersion or by roller application, the latter method being preferred for an automatic process .
After development of the latent electrostatic Image, the devel-oper substance adheres to the copying layer in the form of the image, Appllcatlon of the decoating solution follows.
The decoating solution is distributed over the layer, e.g., by wiping with a cotton pad. Alternatively, the plates may be immersed ln the decoating solution. As a preferred method, the decoating solu-tion ls sprayed upon the layer. Suitably constructed apparatuses also may be used for decoating, e.g., application roll systems. In this manner, the differentiation between hydrophilic and oleophllic areas necessary for offset printing is produced, the image areas represent-ing the oleophilic areas of the printing plate.
The composition of suitable decoating solutions is known, for example, from German Patent No. 1,117,391. Decoating solutions , .
,:
which have proved to be particularly suitable for the inventive process are mixtures of alcohols containing sodium metasilicate or ethanol-amine as the alkaline component. A 5% by weight aqueous solution of phosphoric acid has proved to be suitable as an acid decoating solution .
After treatment with the decoating solution, the printing form is advantageously rinsed with water; if desired, its hydrophobic properties may be further increased by wiping with dilute phosphoric acid solution, After inking with greasy ink, printing may be performed -ln known manner in a planographic printing machine (offset printing).
Alternatlvely, printing forms for letterpress, or, if desired, for gravure prlnting may be produced by the subsequent dissolution of the bared supporting material.
Dissolution may be performed in known one-bite or multi-stage etching machines used for this purpose. If a multi-metal material is used as the support, etching is performed by conventional photoengraving methods. The printing plates obtained by the present process are capable of very long runs.
By the process of the present invention, printing forms and printed circuits may be produced; further, it may be used ln the X-ray and microfilm field.
The lnvention will be further illustrated by reference to the following specific examples:
ExamPle 1 A solution containing 10 g of 2-vinyl-4-(2'-chlorophenyl)-5-(4"-diethyl-aminophenyl)-oxazole, 10 g of a styrene/malèic anhy-dride copolymer with a softening point of 210C, and 20 mg of "Rhodamine FB" in a mixture of 235 ml of glycol monomethyl ether ._ 9 _ .
and 65 ml of butyl acetate is applied to an about lOOp thick, superfici-ally roughened aluminum foil. After evaporation of the solvent, the resulting- photoconductor layer is charged by means of a corona to be negative potential of about 400 volts and exposed under a negative transparency in a re-enlargement apparatus.
At stop 8 and using a 100 watt incandescent lamp as the light source, the exposure time is 30 seconds for an enlargement scale of 1: 5. The latent image is developed with a toner liquid prepared by finely dispersing 1 g of a synthetic ester wax having a saponification value of 130 - 150 and a drop point between 81 and 86 C in a solu-tion of 2 g of a pentaerythritol resin ester as a dispersing agent (e.g. "Pentalyn H" ~), a product of Hercules Powder Company, i-Wilmington, Delaware, USA) in 20 ml of isoparaffin and diluting the resulting dispersion with 1,000 ml of an isoparaffin having a boiling range between 185 and 210C. 0.5 g of soya lecithin is added to the developer liquid as a charge control agent.
The developed plate is converted into a printing form by immersing it for 1 minute in a solution of 35 g of sodium metasilicate hydrate in a mixture of 140 ml of glycerol, 550 ml of ethylene glycol, and 140 ml of ethanol, and then rinsing it with a water ~et while brushing gently. A positive printing form is thus obtained from the negative microfilm original.
Exam~le 2 The procedure described in Example 1 is repeated, except that the synthetic ester wax used in Example 1 as the developer substance is replaced by a phenol resin. The developer is prepared by finely dispersing, in a ball mill, 1 g of a phenol-formaldehyde resin with a , - 10-10468{j5 K-22 2 8 melting point of 75 - 83 C in a solution of 1.5 g of a pentaerythritol resin ester in 70 ml of an isoparaffin, diluting the resuLting dispersion with 1,000 ml of an isoparaffin with a boiling range of 185 - 210C, and adding 0.2 g of soya lecithin as a charge control agent.
Example 3 A solution of 15 g of a condensation product of N-ethylaniline and formaldehyde, 0.41 g of dibromo-succinic acid, and 0.15 g of "Rhodamine FB" in a mixture of 40 ml of toluene, 20 ml of trichloro-ethylene, and 25 ml of methanol is coated upon a mechanically rough-ened aluminum foil. After evaporation of the solvents, a photoconduc-tor layer is obtalned which is charged in the dark, to a negative potential of 350 volts, by means of a coron~. The charged foil is then exposed for approximately 2 minutes in a camera and developed with a toner liquid which protects the image areas from the effect of the de-coating solution by rendering them hydrophobic. The toner liquid is prepared by finely dispersing 1 g of a hard paraffin with a softening range between 50 and 62 C in a solution of 2 g of a pentaerythritol resin ester in 20 ml of an isoparaffin and diluting the resulting disper-slon wlth 1,000 ml of an isoparaffin having a boiling range between 185 and 210C. The developed plate is then bathed for about 2 mlnutes in 5% by weight aqueous phosphoric acid solution, and the dissolved photoconductor substance present in the image-free areas is rinsed off with water.
Example 4 A solution containing 10 g of 2,5-bis-(4'-diethylaminophenyl)-1,3,4-oxadiazole, 10 g of a styrene/maleic anhydride copolymer with a softening point of 210C, and 20 mg of "Rhodamine FB" in 300 ml of glycol monomethyl ether is applied to an about lOOp thick polyester , foil carrying a vacuum-deposited aluminum layer. The coated foil is charged to a negative potential of about 400 volts by means of a corona and is then exposed for 3 seconds, in contact with a transparent film original, to the light of a 100 watt incandescent lamp from a dis-tance of 65 cm. The exposed foil is developed with a developer liquid pre-pared by dissolving or dispersing 1.5 g of a high-vacuum bitumen with a softening range from 130 to 140C ("Bitumen D 130-140 HVB", a product of Shell AG, Hamburg, Germany) and 6.5 g of a pentaerythritol resin ester in 1,000 ml of an isoparaffin with a boiling range between 185 and 210C. In the areas not covered by the bitumen developer, - -the photoconductor layer is removed with a sodium metasilicate solu-tion as described in Example 1. In order to dissolve the about 1~
thick alumlnum layer in the image-free areas, the foil is bathed in 2N
caustlc soda solution. A positive transparency of the original is thus produced which has a very good covering power.
ExamPle 5 Equally good resùlts are obtained by using a chemically nickel-plated polvester film instead of the foil with the vacuum-deposited aluminum layer. In order to remove the nickel layer after the production of the image, a commercial nickel etching solution is used .
Example 6 The photoconductive material described in Example 1 and com-posed of an alumlnum foil with a photoconductor layer thereon is used.
The foil is charged in the dark to a negative potential of 400 volts by means of a corona and is then exposed for approximately 20 seconds in a camera. The latent charge image thus produced on the foil is then developed in a dispersion of 1 g of colophony in a solution of 2 g of a -- ~ K-2228 - 1~46865 pentaerythritol resin ester in 1,000 ml of an isoparaffin with a boiling range between 185 and 210C to which 0.2 g of zirconyl linoleate is added as a charge control agent.
The developed plate is converted into a printing form as de-scribed in Example 1.
Example 7 An alumlnum foil coated with a photoconductor layer as de-scribed ln Example 1 ls charged to a negative potential of 400 volts by means of a corona and exposed in contact with a positive trans-parency (transparent original). The exposure time is 3 seconds, using a 100 watt incandescent lamp at a dlstance of 65 cm. The latent charge image thus produced is developed with a developer liquid pre-pared by finely dispersing 0.3 g of a bleached, white, wax-free shellac powder with a melting point of 63 C in a solution of 0 . 4 g of a pentaerythrltol resin ester ln 1, 000 ml of an isoparaffin with a boil-ing range of 185 - 210C. 3 ml of a 6% by weight solution of zlrconyl linoleate are added to the developer liquid as a charge control agent.
The developed plate is converted into a printing form inthe manner described in Example 1, by removal of the image-free areas with a sodium metasilicate solution.
Example 8 The method described in Example 7 is repeated, except that the developer liquid used for developing the latent charge image is re-placed by a dry developer. For this purpose, 6 g of a bleached, white, wax-free shellac powder with a melting point of 63 C are mixed with 100 g of iron powder having a grain size between 75 and 150~. The mixture is applied to the plate in the manner normally used ln electrophotographic processes, i.e. by means of a magnetic brush.
After development of the latent charge image, the plate is immersed in a decoating solution, as described in Example 1, and thus con-verted into a printing form.
Example 9 A solution of 6 9 of a styrene/maleic anhydride copolymer with a softenlng point of 210C in a mixture of 74 ml of glycol mono-methyl ether and 20 ml of butyl acetate is mechanically applied to a superficially roughened aluminum foil having a thickness of 100 ~
After evaporation of the solvent, the coated foil is charged by means of a corona, using an image-wise blanked-out aluminum foil as a -stencil. The charged image areas have a negative potential of 300 volts. The charge image thus produced is then developed with a toner liquld prepared by dispersing 0 . 5 g of carnauba wax in a solution of l g of a pentaerythrltol resin ester in lO ml of an isoparaffin and diluting the resulting dlsperslon with a solution of 0 . 3 g of zirconyl-
2-ethylhexoate in 1, 000 ml of an isoparaffln wlth a boiling range bet-'~ ween 189 and 210C. The toner-covered foil is converted into a print- ing form as described in Example 1.
It wlll be obvious to those skllled in the art that many modi-fications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such mod~f~cat~ons .
., ,~
It wlll be obvious to those skllled in the art that many modi-fications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all such mod~f~cat~ons .
., ,~
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a process for the preparation of printing forms or metallic etchings from electrographic or electrophotographic reproduction materials composed of a support with a high-ohmic resin layer or a layer containing an organic photoconductive material in a resin binder thereon by image-wise charging or by charging and image-wise exposure, development of the electrostatic image with a finely divided toner, fixing, and removal of the layer in the image-free areas by means of a decoating solution, the improve-ment which comprises developing and fixing the electrostatic image on said layer by treating it with a developer composed of a high-ohmic liquid phase and a finely divided solid phase therein which solid phase is at least one high molecular weight product selected from the group consisting of the high-vacuum bitumen, wax and resin type, which renders the image areas hydrophobic at room temperature, and simultaneously effects development and resistance to the decoating solution.
2. A process according to claim 1 in which the finely divided phase of the developer is a finely divided synthetic ester wax with a saponification value between 130 and 150 and a drop point between about 75 and 90°C.
3. A process according to claim 1 in which the finely divided phase of the developer is a finely divided hard paraffin with a softening range between about 50 and 70°C.
4. A process according to claim 1 in which the finely divided phase of the developer is a finely divided high-vacuum bitumen with a softening range between about 130 and about 150°C.
5. A process according to claim 1 in which the finely divided phase of the developer is a phenol-formaldehyde resin.
6. A process according to claim 1 in which the finely divided phase of the developer is carnanba wax, colophony or shellac.
7. A process according to claim 1, 2 or 3 in which the high ohmic liquid is an isoparaffin having a boiling range between 185 and 210°C
8. A process according to claim 4, 5 or 6 in which the high ohmic liquid is an isoparaffin having a boiling range between 185 and 210°C
9. A process according to claim 1 in which the finely divided solid phase is prepared by dissolving the developer substance in the hot high-ohmic liquid phase and then chilling the solution to room temperature.
10. A process according to claim 1 in which the decoating solution is an alcoholic mixture to which sodium metasilicate or ethanolamine is added as the alkaline component.
11. A process according to claim 1 including etching of the bared image-free areas of the support.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2322046A DE2322046C3 (en) | 1973-05-02 | 1973-05-02 | Process for the production of printing forms |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1046865A true CA1046865A (en) | 1979-01-23 |
Family
ID=5879815
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA198,310A Expired CA1046865A (en) | 1973-05-02 | 1974-04-29 | Process for the preparation of printing forms |
Country Status (17)
| Country | Link |
|---|---|
| JP (1) | JPS597100B2 (en) |
| AR (1) | AR208175A1 (en) |
| AT (1) | AT332895B (en) |
| AU (1) | AU6837274A (en) |
| BE (1) | BE814362A (en) |
| BR (1) | BR7403475D0 (en) |
| CA (1) | CA1046865A (en) |
| CH (1) | CH593502A5 (en) |
| DE (1) | DE2322046C3 (en) |
| DK (1) | DK144838C (en) |
| ES (1) | ES425859A1 (en) |
| FR (1) | FR2227952B1 (en) |
| GB (1) | GB1465926A (en) |
| IE (1) | IE39427B1 (en) |
| IT (1) | IT1004493B (en) |
| NL (1) | NL7404997A (en) |
| ZA (1) | ZA742781B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5755949A (en) * | 1993-12-22 | 1998-05-26 | Agfa-Gevaert Ag | Electrochemical graining method |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54144203A (en) * | 1978-05-01 | 1979-11-10 | Fuji Yakuhin Kogyo Kk | Method of making flat printing plate |
| JPS5666307A (en) * | 1979-10-04 | 1981-06-04 | Hitachi Ltd | Rolling mill |
| JPS5671507A (en) * | 1979-11-16 | 1981-06-15 | Ishikawajima Harima Heavy Ind Co Ltd | Rolling mill |
| NL8003132A (en) * | 1980-05-29 | 1982-01-04 | Veco Beheer Bv | METHOD FOR FORMING METAL PREPARATIONS. |
| JPS6018243B2 (en) * | 1980-07-07 | 1985-05-09 | 株式会社日立製作所 | rolling roll |
| DE3038865C1 (en) * | 1980-10-15 | 1982-12-23 | SMS Schloemann-Siemag AG, 4000 Düsseldorf | Roll stand with axially movable rolls |
| ZA825152B (en) * | 1981-08-03 | 1983-07-27 | Polychrome Corp | Aqueous composition-sensitive photoconductive composition |
| JPS6149895A (en) * | 1985-06-24 | 1986-03-11 | Konishiroku Photo Ind Co Ltd | Production of printing plate |
| DE3532346A1 (en) * | 1985-09-11 | 1987-03-12 | Hoechst Ag | METHOD FOR PRODUCING PRINTING FORMS |
| JPS62254911A (en) * | 1986-04-28 | 1987-11-06 | Sumitomo Metal Ind Ltd | Octuple mill |
| JPS62161411A (en) * | 1986-10-03 | 1987-07-17 | Hitachi Ltd | Rolling mill and rolling method |
| DE3635303A1 (en) | 1986-10-17 | 1988-04-28 | Hoechst Ag | METHOD FOR REMOVING MODIFICATION OF CARRIER MATERIALS MADE OF ALUMINUM OR ITS ALLOYS, AND THEIR ALLOYS AND THEIR USE IN THE PRODUCTION OF OFFSET PRINTING PLATES |
| DE4001466A1 (en) * | 1990-01-19 | 1991-07-25 | Hoechst Ag | Electrochemical roughening of aluminium for printing plate mfr. - using combination of mechanical and electrochemical roughening before and/or after main electrochemical roughening stage |
-
1973
- 1973-05-02 DE DE2322046A patent/DE2322046C3/en not_active Expired
-
1974
- 1974-01-01 AR AR253391A patent/AR208175A1/en active
- 1974-04-11 NL NL7404997A patent/NL7404997A/xx not_active Application Discontinuation
- 1974-04-29 IT IT50670/74A patent/IT1004493B/en active
- 1974-04-29 CA CA198,310A patent/CA1046865A/en not_active Expired
- 1974-04-29 FR FR7414841A patent/FR2227952B1/fr not_active Expired
- 1974-04-29 BR BR3475/74A patent/BR7403475D0/en unknown
- 1974-04-29 AT AT353274A patent/AT332895B/en not_active IP Right Cessation
- 1974-04-29 CH CH585474A patent/CH593502A5/xx not_active IP Right Cessation
- 1974-04-29 BE BE143761A patent/BE814362A/en not_active IP Right Cessation
- 1974-04-29 AU AU68372/74A patent/AU6837274A/en not_active Expired
- 1974-04-30 ES ES425859A patent/ES425859A1/en not_active Expired
- 1974-04-30 GB GB1881974A patent/GB1465926A/en not_active Expired
- 1974-04-30 IE IE908/74A patent/IE39427B1/en unknown
- 1974-05-01 DK DK237874A patent/DK144838C/en active
- 1974-05-01 ZA ZA00742781A patent/ZA742781B/en unknown
- 1974-05-02 JP JP49049665A patent/JPS597100B2/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5755949A (en) * | 1993-12-22 | 1998-05-26 | Agfa-Gevaert Ag | Electrochemical graining method |
Also Published As
| Publication number | Publication date |
|---|---|
| CH593502A5 (en) | 1977-12-15 |
| AT332895B (en) | 1976-10-25 |
| JPS5019510A (en) | 1975-03-01 |
| ES425859A1 (en) | 1976-06-16 |
| BE814362A (en) | 1974-10-29 |
| AR208175A1 (en) | 1976-12-09 |
| FR2227952B1 (en) | 1976-10-15 |
| DK144838C (en) | 1982-11-01 |
| DK144838B (en) | 1982-06-14 |
| IE39427L (en) | 1974-11-02 |
| DE2322046A1 (en) | 1974-11-07 |
| AU6837274A (en) | 1975-10-30 |
| GB1465926A (en) | 1977-03-02 |
| FR2227952A1 (en) | 1974-11-29 |
| IE39427B1 (en) | 1978-10-11 |
| DE2322046B2 (en) | 1979-03-22 |
| DE2322046C3 (en) | 1979-11-22 |
| NL7404997A (en) | 1974-11-05 |
| JPS597100B2 (en) | 1984-02-16 |
| IT1004493B (en) | 1976-07-10 |
| ATA353274A (en) | 1976-02-15 |
| ZA742781B (en) | 1975-04-30 |
| BR7403475D0 (en) | 1974-12-24 |
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