EP0253358B1 - Méthode pour empêcher la génération de gaz indésirable entre les électrodes d'un système d'impression par électrocoagulation - Google Patents

Méthode pour empêcher la génération de gaz indésirable entre les électrodes d'un système d'impression par électrocoagulation Download PDF

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Publication number
EP0253358B1
EP0253358B1 EP87110136A EP87110136A EP0253358B1 EP 0253358 B1 EP0253358 B1 EP 0253358B1 EP 87110136 A EP87110136 A EP 87110136A EP 87110136 A EP87110136 A EP 87110136A EP 0253358 B1 EP0253358 B1 EP 0253358B1
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EP
European Patent Office
Prior art keywords
oxide
positive electrode
oil
olefinic substance
electrodes
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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 - Lifetime
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EP87110136A
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German (de)
English (en)
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EP0253358A3 (en
EP0253358A2 (fr
Inventor
Adrien Castegnier
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Elcorsy Inc
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Elcorsy Inc
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Priority to AT87110136T priority Critical patent/ATE64716T1/de
Publication of EP0253358A2 publication Critical patent/EP0253358A2/fr
Publication of EP0253358A3 publication Critical patent/EP0253358A3/en
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
    • B41C1/00—Forme preparation
    • B41C1/10—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme
    • B41C1/105—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by electrocoagulation, by electro-adhesion or by electro-releasing of material, e.g. a liquid from a gel

Definitions

  • the present invention relates to improvements in the field of electrocoagulation. More particularly, the invention is concerned with an improved method of reproducing an image by the electrocoagulation of an electrolytically coagulable colloid.
  • Applicant has already described in his U.S. Patent No. 3,892,645 of July l, l975 an electrocoagulation printing method and system in which a thin layer of a liquid composition containing a colloid such as gelatin or albumin, water and a chloride-based electrolyte is interposed between at least one pair of opposite negative and positive electrodes spaced from one another to define a gap which is filled by the liquid composition.
  • a colloid such as gelatin or albumin
  • a chloride-based electrolyte is interposed between at least one pair of opposite negative and positive electrodes spaced from one another to define a gap which is filled by the liquid composition.
  • a major problem encountered with such an electrocoagulation printing method is that since the negative electrodes are generally energized more than once in the reproduction of an image, these become polarized resulting in secondary electrolytic reactions causing the generation of hydrogen bubbles which remain trapped at the interface of the negative electrodes as well as the generation of chlorine and oxygen bubbles which remain trapped at the interface of the positive electrode, and these gases thus adversely affect the image reproduction. It has been observed that when forming the first series of dots of coagulated colloid there is no such undesirable hydrogen generation and accumulation at the negative electrodes, but after the first electrocoagulation hydrogen generated by electrolysis slowly builds up and creates an electrical resistance at the interface of the negative electrodes such as to cause the formation of the dots of coagulated colloid to become erratic.
  • the chlorine and oxygen gases which are generated at the positive electrode upon the formation of the first series of dots of coagulated colloid also create an electrical resistance at the interface of the positive electrode, which further contributes to the erratic formation of the dots of coagulated colloid.
  • the chlorine and oxygen gases remain trapped underneath the dots of coagulated colloid and the coagulated colloid strongly adheres to the surface of the electrode, thus rendering the transfer or removal of the dots more difficult.
  • a method of preventing undesirable gas generation between a pair of opposite, electrically energized negative and positive electrodes spaced from one another by a gap filled with an aqueous electrolyte solution which comprises coating the positive electrode with an olefinic substance to form micro-droplets thereof on the surface of the positive electrode prior to electrically energizing the electrodes such that upon electrical energization gas generated as a result of electrolysis is consumed by reaction with the olefinic substance, the reaction being carried out in the presence of a metallic oxide catalyst. In this manner, undesirable gas generation between the electrodes is prevented.
  • the method of the invention is particularly useful in electrocoagulation printing systems where an image is reproduced by electrocoagulation of an electrolytically coagulable colloid on a positive electrode to form dots of coagulated colloid representative of a desired image, the invention enabling the electrical resistance which is created at the interface of the negative electrode by the accumulation of hydrogen and causes an erratic formation of the dots of coagulated colloid to be suppressed.
  • the present invention therefore also provides, in another aspect thereof, an improved method of reproducing an image by electrocoagulation of an electrolytically coagulable colloid, wherein a layer of an aqueous colloidal dispersion containing an electrolytically coagulable colloid, water and a soluble electolyte is interposed between at least one pair of opposite, electrolytically inert negative and positive electrodes spaced from one another by a gap filled with the aqueous colloidal dispersion and the electrodes are electrically energized to pass electric current through the layer at selected points to cause point-by-point selective coagulation and adherence of the colloid on the positive electrode and formation of a series of corresponding dots of coagulated colloid representative of a desired image, the improvement residing in coating the positive electrode with an olefinic substance to form micro-droplets thereof on the surface of the positive electrode prior to electrically energizing the electrodes such that upon electrical energization hydrogen generated as a result of electrolysis is consumed by reaction with the olefinic
  • the chlorine ions originating from the chloride salt used as electrolyte, such as an alkali metal chloride, are believed to react with the double bond of the olefinic substance, thereby chlorinating same.
  • an unsaturated fatty acid is used as the olefinic substance
  • the coating of olefinic substance on the surface of the positive electrode be in the form of micro-droplets of the olefinic substance rather than a continuous film thereof which would otherwise create an electrical insulation preventing the passage of electric current.
  • micro-droplets may have, for instance, a size ranging from about 2 to about 10 ⁇ m.
  • micro-droplets of olefinic substance do not in any way affect the precision or resolution of the dots of coagulated colloid, nor do they slow down in any way the speed of electrocoagulation. In fact, it has been observed that the dots of coagulated colloid which are formed by the electrocoagulation carried out with micro-droplets of olefinic substance on the positive electrode have an increased optical density.
  • Suitable olefinic substances which may be used according to the invention include unsaturated fatty acids such as arachidonic acid, linoleic acid, linolenic acid, oleic acid and palmitoleic acid, unsaturated vegetable oils such as corn oil, linseed oil, olive oil, peanut oil and soybean oil, and unsaturated vegetable waxes such as carnauba wax. Where an unsaturated vegetable wax is used, it is generally mixed with an unsaturated fatty acid such as oleic or linoleic acid to form a paste for application onto the positive electrode, or it may be liquefied by heat and applied as a liquid.
  • unsaturated fatty acids such as arachidonic acid, linoleic acid, linolenic acid, oleic acid and palmitoleic acid
  • unsaturated vegetable oils such as corn oil, linseed oil, olive oil, peanut oil and soybean oil
  • unsaturated vegetable waxes such as carnauba wax
  • the metal of the positive electrode is not easily wetted by the unsaturated fatty acids which are liquid at room temperature, or by the unsaturated vegetable oils or waxes, micro-droplets of the olefinic substance can be readily formed on the surface of the positive electrode by applying the olefinic substance by means of a cloth impregnated with the latter.
  • suitable metallic oxide catalysts which may be used according to the invention include aluminum oxide, ceric oxide, chromium oxide, cupric oxide, cuprous oxide, ferric oxide, ferrous oxide, lead oxide, magnesium oxide, manganese oxide, and zinc oxide.
  • Ferric oxide is the preferred metallic oxide catalyst.
  • the olefinic substance is an unsaturated vegetable oil
  • it is advantageously applied to the positive electrode in the form of a dispersion containing the metallic oxide catalyst.
  • the metallic oxide catalyst is preferably present in an amount of about l to about l0% by weight, based on the total weight of the dispersion.
  • Particularly preferred dispersion are those containing about 88 wt.% of an unsaturated vegetable oil such as olive oil, corn oil or peanut oil, about 2 wt.% of oleic acid and about l0 wt.% of ferric oxide.
  • the method according to the invention not only prevents undesirable gas generation between electrodes of an electrocoagulation printing system, but also greatly facilitates the transfer of the coagulated colloid onto an end-use support when the dots of coagulated colloid are contacted with an end-use support to imprint the latter with the image reproduced.
  • an unsaturated vegetable oil the micro-droplets of vegetable oil are converted upon hydrogenation into micro-droplets of fat weakening the adherence of the dots of coagulated colloid to the positive electrode and thereby facilitating the transfer of the coagulated colloid onto the end-use support upon contact therewith.
  • the micro-droplets of fat or other ethylenically saturated product which remain on the positive electrode can be removed by cleaning the surface of the electrode with an organic solvent such as acetone, petroleum ether or toluene, or with any commercially available detergent solution.
  • an organic solvent such as acetone, petroleum ether or toluene, or with any commercially available detergent solution.
  • a positive electrode in the form of a revolving cylinder having a cylindrical surface made of stainless steel is partially immersed in a bath containing an electrolytically coagulable colloid, water and a soluble electrolyte and maintained at substantially constant temperature, the stainless steel having a surface layer of chromium oxide.
  • the printing head which is operative to form dots of coagulated colloid on the surface of the positive electrode comprises a plurality of electrically-insulated juxtaposed negative electrodes spaced from the positive electrode surface by a substantially constant electrode gap of the order of 50 ⁇ m.
  • the cylindrical surface Prior to immersing the cylinder into the bath containing the aqueous colloidal dispersion, the cylindrical surface was coated with oleic acid to form thereon micro-droplets of unsaturated fatty acid. After immersion into the bath, the oleic acid coated cylinder was set into revolving motion to fill the electrode gap with the aqueous colloidal dispersion. Selected ones of the negative electrodes were then electrically energized to cause point-by-point selective coagulation and adherence of the colloid onto the positive electrode surface, thereby forming a series of corresponding dots of coagulated colloid representative of a desired image.
  • Example l was repeated, except that the oleic acid was replaced by linoleic acid. Essentially the same results were obtained.
  • Example l was repeated, except that the surface of the positive electrode was coated with a dispersion containing about 88 wt.% olive oil, about 2 wt.% oleic acid and about l0 wt.% ferric acid. Essentially the same results were obtained.
  • Example l was repeated, except that the surface of the positive electrode was coated with a dispersion containing about 88 wt.% corn oil, about 2 wt.% oleic acid and about l0 wt.% ferric oxide. Essentially the same results were obtained.
  • Example l was repeated, except that the surface of the positive electrode was coated with a dispersion containing about 95 wt.% oleic acid and about 5 wt.% ferric oxide. Essentially the same results were obtained.
  • dots of coagulated colloid could be formed at a rate, of about 2,000,000 per second, with half-tones being clearly reproduced.
  • example l The procedure of example l was followed, except that the oleic acid was replaced by liquefied lauric acid, a saturated fatty acid. About 7 wt.% ferric oxide was admixed with the lauric acid. Upon repeated electrical energization of the same negative electrodes, there was observed a generation of hydrogen bubbles which remained trapped at the interface of the negative electrodes and thus hindered the image reproduction.
  • Example l The procedure of Example l was repeated, except that the surface of the positive electrode was coated with a dispersion containing about 90 wt.% mineral oil and about l0 wt.% ferric oxide. The same results as in Comparative Example l were obtained.

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  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
  • Duplication Or Marking (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
  • Printing Methods (AREA)
  • Electrodes For Compound Or Non-Metal Manufacture (AREA)

Claims (21)

  1. Procédé pour empêcher la génération de gaz indésirable entre une paire d'électrodes opposées négative et positive excitées électriquement, ces électrodes étant espacées l'une de l'autre par un espace rempli par une solution d'électrolyte aqueuse, caractérisé en ce que l'électrode positive est revêtue d'une substance oléfinique de façon à former des micro-gouttelettes de celle-ci sur la surface de l'électrode positive avant d'exciter électriquement lesdites électrodes de façon à ce que, lors de l'excitation électrique, le gaz généré en conséquence de l'électrolyse soit consommé par réaction avec ladite substance oléfinique, ladite réaction étant effectuée en présence d'un catalyseur en oxyde métallique, empêchant par conséquent la génération de gaz indésirable entre lesdites électrodes.
  2. Procédé selon la revendication 1, caractérisé en ce que ladite substance oléfinique est sélectionnée dans le groupe composé des acides gras insaturés, des cires et des huiles végétales insaturées.
  3. Procédé selon la revendication 2, caractérisé en ce que ladite substance oléfinique est un acide gras insaturé sélectionné parmi le groupe composé de l'acide arachidonique, de l'acide linoléïque, de l'acide linolénique, de l'acide oléïque et de l'acide palmitoléïque.
  4. Procédé selon la revendication 2, caractérisé en ce que ladite substance oléfinique est une huile végétale insaturée sélectionnée parmi le groupe composé de l'huile de maïs, de l'huile de lin, de l'huile d'olive, de l'huile d'arachide et de l'huile de soja.
  5. Procédé selon la revendication 3, caractérisé en ce que ledit acide gras insaturé est de l'acide linoléïque ou de l'acide oléïque, et dans lequel ladite électrode positive est faite en acier inoxydable ayant une couche de surface en oxyde de chrome, ledit oxyde de chrome jouant le rôle dudit catalyseur en oxyde métallique.
  6. Procédé selon la revendication 1, caractérisé en ce que ladite substance oléfinique est une huile végétale insaturée et est appliquée à ladite électrode positive sous la forme d'une dispersion contenant ledit catalyseur en oxyde métallique.
  7. Procédé selon la revendication 6, caractérisé en ce que ledit catalyseur en oxyde métallique est présent dans une proportion d'environ 1 à environ 10% en poids, par rapport au poids total de ladite dispersion.
  8. Procédé selon la revendication 6, caractérisé en ce que ledit catalyseur en oxyde métallique est sélectionné parmi le groupe composé de l'oxyde d'aluminium, de l'oxyde cérique, de l'oxyde de chrome, de l'oxyde cuivrique, de l'oxyde cuivreux, de l'oxyde ferrique, de l'oxyde ferreux, de l'oxyde de plomb, de l'oxyde de magnésium, de l'oxyde de manganèse et de l'oxyde de zinc.
  9. Procédé selon la revendication 8, caractérisé en ce que ladite dispersion contient environ 88% en poids d'une huile végétale insaturée sélectionnée parmi le groupe composé de l'huile d'olive, de l'huile de maïs, et de l'huile d'arachide, environ 2% en poids d'acide oléïque et environ 10% en poids d'oxyde ferrique.
  10. Procédé de reproduction d'une image par électrocoagulation d'un colloïde électrolytiquement coagulable, dans lequel une couche d'une dispersion colloïdale aqueuse contenant un colloïde électrolytiquement coagulable, de l'eau et un électrolyte soluble est interposée entre au moins une paire d'électrodes opposées négative et positive électrolytiquement inertes, espacées l'une de l'autre par un espace rempli par ladite dispersion colloïdale aqueuse, et lesdites électrodes sont électriquement excitées pour transmettre du courant électrique à travers la couche en des points sélectionnés de façon à provoquer une adhérence et une coagulation sélectives point par point du colloïde sur l'électrode positive et la formation d'une série de points correspondants de colloïde coagulé représentatifs d'une image désirée, caractérisé en ce que l'électrode positive est revêtue d'une substance oléfinique de façon à former des micro-gouttelettes de celle-ci sur la surface de l'électrode positive avant d'exciter électriquement lesdites électrodes de telle sorte que, lors de l'excitation électrique, l'hydrogène généré en conséquence de l'électrolyse soit consommé par réaction avec ladite substance oléfinique, ladite réaction étant effectuée en présence d'un catalyseur en oxyde métallique, empêchant par conséquent la génération et l'accumulation indésirables d'hydrogène sur l'électrode négative.
  11. Procédé selon la revendication 10, caractérisé en ce que ladite substance oléfinique est sélectionnée parmi le groupe composé des acides gras insaturés, des cires et des huiles végétales insaturées.
  12. Procédé selon la revendication 11, caractérisé en ce que ladite substance oléfinique est un acide gras insaturé sélectionné parmi le groupe composé de l'acide arachidonique, de l'acide linoléique, de l'acide linolénique, de l'acide oléique et de l'acide palmitoléique.
  13. Procédé selon la revendication 11, caractérisé en ce que ladite substance oléfinique est une huile végétale insaturée sélectionnée parmi le groupe composé de l'huile de maïs, de l'huile de lin, de l'huile d'olive, de l'huile d'arachide et de l'huile de soja.
  14. Procédé selon la revendication 12, caractérisé en ce que ledit acide gras insaturé est de l'acide linoléique ou de l'acide oléique et dans lequel ladite électrode positive est faite en acier inoxydable ayant une couche de surface en oxyde de chrome, ledit oxyde de chrome jouant le rôle dudit catalyseur en oxyde métallique.
  15. Procédé selon la revendication 10, caractérisé en ce que ladite substance oléfinique est une huile végétale insaturée et est appliquée à ladite électrode positive sous la forme d'une dispersion contenant ledit catalyseur en oxyde métallique.
  16. Procédé selon la revendication 15, caractérisé en ce que ledit catalyseur en oxyde métallique est présent en une proportion d'environ 1 à environ 10% en poids, par rapport au poids total de ladite dispersion.
  17. Procédé selon la revendication 15, caractérisé en ce que ledit catalyseur en oxyde métallique est sélectionné parmi le groupe composé de l'oxyde d'alluminium, de l'oxyde cérique, de l'oxyde de chrome, de l'oxyde cuivrique, de l'oxyde cuivreux, de l'oxyde ferrique, de l'oxyde ferreux, de l'oxyde de plomb, de l'oxyde de magnésium, de l'oxyde de manganèse, et de l'oxyde de zinc.
  18. Procédé selon la revendication 17, caractérisé en ce que ladite dispersion contient environ 88% en poids d'une huile végétale insaturée sélectionnée parmi le groupe composé de l'huile d'olive, de l'huile de maïs et de l'huile d'arachide, environ 2% en poids d'acide oléique et environ 10% en poids d'oxyde ferrique.
  19. Procédé selon la revendication 10, caractérisé en ce que lesdits points de colloïde coagulé sont mis en contact avec un support d'utilisation final afin de provoquer le transfert du colloïde coagulé sur ledit support d'utilisation final et d'imprimer par conséquent ladite image sur ledit support d'utilisation final, et en ce que ladite substance oléfinique est une huile végétale insaturée telle que lors de la réaction, les microgouttelettes d'huile végétale soient converties en microgouttelettes de graisse, diminuant l'adhérence desdits points de colloïde coagulé sur ladite électrode positive et facilitant par conséquent le transfert dudit colloïde coagulé sur ledit support d'utilisation final lors du contact avec celui-ci.
  20. Procédé selon la revendication 12, caractérisé en ce que ladite électrode positive est faite en acier inoxydable ayant une couche de surface en oxyde de chrome, et en ce que ledit acide gras insaturé est de l'acide oléique et est appliqué sous la forme d'une dispersion contenant de l'oxyde ferrique jouant le rôle dudit catalyseur en oxyde métallique, ledit colloïde coagulable électrolytiquement comportant un polyacrylamide linéaire ayant un poids moléculaire de 250.000 environ.
  21. Procédé selon la revendication 10, caractérisé en ce que ledit électrolyte est un sel chlorure et en ce que, lors de l'excitation électrique desdites électrodes, le chlore et l'oxygène générés en conséquence de l'électrolyse sont consommés par réaction avec ladite substance oléfinique, ce qui empêche par conséquent la génération de chlore et d'oxygène indésirables à l'électrode positive.
EP87110136A 1986-07-18 1987-07-14 Méthode pour empêcher la génération de gaz indésirable entre les électrodes d'un système d'impression par électrocoagulation Expired - Lifetime EP0253358B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT87110136T ATE64716T1 (de) 1986-07-18 1987-07-14 Verfahren, um unerwuenschte gaserzeugung zwischen elektroden eines elektrokoagulationsdrucksystems zu verhindern.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CA514197 1986-07-18
CA000514197A CA1249238A (fr) 1986-07-18 1986-07-18 Prevention de la generation indesirable de gaz entre les electrodes d'un systeme d'impression par electrocoagulation

Publications (3)

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EP0253358A2 EP0253358A2 (fr) 1988-01-20
EP0253358A3 EP0253358A3 (en) 1988-12-14
EP0253358B1 true EP0253358B1 (fr) 1991-06-26

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EP87110136A Expired - Lifetime EP0253358B1 (fr) 1986-07-18 1987-07-14 Méthode pour empêcher la génération de gaz indésirable entre les électrodes d'un système d'impression par électrocoagulation

Country Status (5)

Country Link
EP (1) EP0253358B1 (fr)
JP (1) JPH0710618B2 (fr)
AT (1) ATE64716T1 (fr)
CA (1) CA1249238A (fr)
DE (1) DE3771007D1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3067771B1 (ja) * 1999-07-12 2000-07-24 ヤマハ株式会社 印刷装置

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3752746A (en) * 1972-02-25 1973-08-14 A Castegnier Electrolytic printing method and system
US3892645A (en) * 1973-06-06 1975-07-01 Adrien Castegnier Printing method and system by gelatin coagulation
CA1250249A (fr) * 1984-05-11 1989-02-21 Adrien Castegnier Impression par coagulation electrolytique d'une solution colloidale; composition colloidale utilisee a cette fin
CA1205778A (fr) * 1984-05-16 1986-06-10 Adrien Castegnier Reproduction d'images par electrocoagulation d'un colloide applique en surface
US4555320A (en) * 1984-05-25 1985-11-26 Elcorsy Inc. Image reproduction by in plane electro-coagulation of a colloid
CA1279603C (fr) * 1986-02-20 1991-01-29 Adrien Castegnier Impression monochrome et polychrome d'une image reproduite par electrocoagulation d'un colloide

Also Published As

Publication number Publication date
EP0253358A3 (en) 1988-12-14
ATE64716T1 (de) 1991-07-15
JPH0710618B2 (ja) 1995-02-08
CA1249238A (fr) 1989-01-24
JPS6331784A (ja) 1988-02-10
EP0253358A2 (fr) 1988-01-20
DE3771007D1 (de) 1991-08-01

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