CA1249238A - Method of preventing undesirable gas generation between electrodes of an electrocoagulation printing system - Google Patents
Method of preventing undesirable gas generation between electrodes of an electrocoagulation printing systemInfo
- Publication number
- CA1249238A CA1249238A CA000514197A CA514197A CA1249238A CA 1249238 A CA1249238 A CA 1249238A CA 000514197 A CA000514197 A CA 000514197A CA 514197 A CA514197 A CA 514197A CA 1249238 A CA1249238 A CA 1249238A
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- Canada
- Prior art keywords
- oxide
- positive electrode
- oil
- electrodes
- olefinic substance
- Prior art date
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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
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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)
- Electrodes For Compound Or Non-Metal Manufacture (AREA)
- Printing Methods (AREA)
Abstract
"METHOD OF PREVENTING UNDESIRABLE
GAS GENERATION BETWEEN ELECTRODES
OF AN ELECTROCOAGULATION PRINTING SYSTEM"
Abstract of the Disclosure The invention is concerned with 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. According to the inven-tion, the positive electrode is coated 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.
GAS GENERATION BETWEEN ELECTRODES
OF AN ELECTROCOAGULATION PRINTING SYSTEM"
Abstract of the Disclosure The invention is concerned with 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. According to the inven-tion, the positive electrode is coated 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.
Description
BACKGROUND OF THE-INVENTI~N
The present invention relates to improvements in the field of electrocoagulation. More particularly~
the invention is concerned with an improved method or 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 1~1975 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 an 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. In one embodiment, there is a plurality of electrically-insulated juxtaposed negative electrodes and selected ones there-of are electrically energized to pass electric pulses through the layer at selected points to cause point-by-point selective coagula-tion and adherence of the colloid in variable thickness on the positive electrode directly opposi-te each energized negative electrode, thereby forming dots of coagulated colloid representative of a ~ desired image which may be transferred on-to an end-use support, such as paper.
A major problem encountered with such an electrocoagulation prin-ting 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 ;~
23~3 trapped at the interface of the negative electrodes and thus adversely affect the image reproduction. It has been observed tha-t when forming the first series of dots of coagulated colloid there is no such undesirable gas gene-ration and accumulation at the nega-tive electrodes, but after the first electrocoagulation hydrogen generated by electrolysis slowly builds up and creates an electrical resistance at the in-terEace of the negative electrodes su~h as to cause the formation of the dots of coagulated colloid to become erratic.
S~MMARY OF THE INVENTION
It is therefore an object of the present inven-tion to overcome the above drawback and to provide a method of preventing undesirable gas generation between electrodes of, for instance, an electrocoagul-ation printing system.
According to a broad aspect of the invention, there is provided a me-thod of preventing undesirable gas generation between a pair of opposite, electrically ener-gized negative and positive electrodes spaced from one another by a gap filled with an aqueous electrolyte solution, which comprises coating the positive elec-trode with an olefinic substance to form tnicro-droplets thereof on the surface of the positive electrode prior -to electrically energizing the electrodes such that upon electrical ener-gization gas generated as a resul-t oE electrolysis is consumed by reaction with -the olefinic substance, -the reaction being carried out in the presence of a me-tallic oxide catalyst. In this manner, undesirable gas genera-tion between the electrodes is prevented.
, i 3~3 The method of the invention is particularly useful in electrocoagulation printing systems where an image is reproduced by electrocoagulation of an electroly-tically 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 a-t the interface of the negative electrode W~
by the accumulation of hydrogen and~causes an erratic formation of the dots of coagulated colloidlto be suppres-sed.
The present invention therefore also provides, in another aspect thereof, an improved method of reprodu-cing an image by electrocoagulation of an electrolytically coagulable colloid, wherein a layer of an aqueous colloidal dispersion containing an electrolytically coagulable colloidj water and a soluble electrolyte is interposed between a-t least one pair of opposite, electrolytically inert negative and positive electrodes spaced from one another by a gap filled with the aqueous colloidal disper-sion 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 improvemen-t residing in coating -the posi-tive electrode with an olefinic substance to form micro-droplets thereof on the surface of the posi-tive electrode prior to electrically energizing -the electrodes ~ tha-t upon electrical energization hydrogen generated as a result of electrolysis is consumed by reaction wi-th -the olefinic substance, the reaction being carried , . . .
out in the presence of a metallic oxide catalyst, thereby preventin~ undesirable hydrogen generation and accumulation at the negative electrode.
It has been surprisingly found, according to the invention, that by coating the positive electrode with an olefinic substance undesirable hydrogen yeneration and accumulation at the negative electrode is prevented as the hydrogen is consumed by reaction with the olefinic substance, provided that the reaction be carried out in the presence of a metallic oxyde catalyst which is either already present as a surface layer on the positive electrode utilized or is admixed with the olefinic substance. It is believed that the reaction involved ls one of hydrogena-tion whereby the olefinic substance is converted into an ethylenically saturated product.
It is also important that the coating of olefi nic 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 other-wise create an electrical insulation preventing the passage of electric current. Such micro-droplets may have, for instance, a size ranging from about 2 to about 10 ,u.
The micro-droplets of olefinic substance do ' i, not in any way affect the precision or resolu-tion 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.
Examples of suitable olefinic substances which may be used according to the inven-tion include unsatura-ted fatty acids such as arachidonic acid, linoleic acid, linolenic acid, oleic acid and palmi-toleic 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 posi-tive electrode, or it may be liquefied by heat and applied as a liquid.
Since the metal of -the positive electrode is not ea~ily wetted by the unsatura-ted fat-ty acids which are liquid a-t room -tempera-ture, or by -the unsaturated vege-table oils or waxes, micro-drople-ts of the olefinic subs-tance can be readily formed on the surface of the positive electrode by applying the olefinic substance by means of a cloth impregna-ted with the la-t-ter.
:~, ?
It has been observed that when an unsa-turated fatty acid such as linoleic or oleic acid is used as the olefinic substance and where the positive electrode utilized is made of stainless steel having a chromium oxide surface layer, the chromium oxide in the surface layer of the electrode is sufficien-t -to act as the me-tallic oxide ca-talyst for hydrogenating the unsaturated fatty acid to a satura-ted fatty acid.
Thus, no additional metallic oxide ca-talyst is necessary. However, when it is desired to reproduce half--tones, a metallic oxide catalyst is usually admixed with the unsatura-ted fatty acid for obtaining an image reproduc-tion of high quality.
Examples of suitable metallic oxide cata-lysts 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 ca-talys-t.
When the olefinic subs-tance is an unsa--turated vege-table oil, it is advantageously applied to the positive elec-trode in -the form of a dispersion containing -the me-tallic oxide catalyst. The metallic oxide catalyst is preferably presen-t in an amount of about 1 to about 10% by weigh-t, based on -the total weigh-t of the dispersion. Particularly preferred dispersion-~are -those containing abou-t 88 wt.% of an ' :' ~2~38 unsaturated vegetable oil such as olive oil, corn oil or peanut oil, about 2 wt.% of oleic acid and about 10 wt.% of ferric oxide.
The method according to the invention not only prevents undesirable gas generation between electrodes of an electrocoagula-tion 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. Indeed, by using as olefinic substance an unsaturated vegetable oil, the micro-droplets of vegetable oil are converted upon hydrogenation into micro-droplets of fa-t weakening the adherence of the dots of coagulated colloid to the positive electrode and thereby facilitating the transfer of the coagu-lated colloid onto the end-use support upon contact therewith.
After electrocoagulation and transfer of the coagulated colloid on-to an end-use support, the micro-droplets of fat or other ethylenically satu-rated product which remain on the positive electrode can be removed by cleaning the surface of the electrode with an organic solvent such as acetone, Detroleum ether or toluene, or with any commercially available detergent solution.
The following non-limiting examples illus-trate the invention.
~L2~3(~
An elec-trocoagulation printing system according to one of the embodiments described in Applicant's U.S. Patent No. 3,892,6~5 was used. In such an embodiment, a positive electrode in the form oE a revolving cylinder having a cylindrical surface made of stainless steel is pa:rtially immersed in a bath containing an electrolytically coagulahle colloid, water and a soluble electrolyte and main-tained at substantially constant temperature, the stainless steel having a surface layer of chromium oxide. The printing head which is operative to form do-ts of coagulated colloid on the surface of the positive electrode comprises a plurality of electri-cally-insulated juxtaposed negative elec-trodes spaced from the positive electrode surface by a substan-tially constant electrode gap of the order of 50 lu.
Prior to immersing the cylinder into the bath containing -the aqueous coll.oidal dispersion, the cylindrical surface was coated with oleic acid to form thereon micro-droplets of unsaturated fatty acid. After immersion in-to -the ba-th, the oleic acid coated cylinder was set into revolving motion to fill -the elec-trode gap with -the aqueous colloidal disper-sion. Selected ones of the negative electrodes were then electrically energized to cause point-by-point selec-tive coagulation and adherence of the colloid onto the positive electrode surface, thereby forming a series of corresponding dots of coagulated colloid representative of a deisired image.
'' 1 ~`'~1 During -the electrocoagulation, no undesir-able hydrogen generation and accumulation at the negative electrodes could be observed. The resulting dots of coagulated colloid were also easily transfer-rable onto an end-use support, such as paper.
Example 1 was repeated, except that the oleic acid was replaced by linoleic acid. Essential-ly the same results were obtained.
-Example 1 was repeated, excep-t that -the sur-face of -the positive electrode was coa-ted with a dispersion containing about 88 wt.% olive oil, about
The present invention relates to improvements in the field of electrocoagulation. More particularly~
the invention is concerned with an improved method or 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 1~1975 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 an 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. In one embodiment, there is a plurality of electrically-insulated juxtaposed negative electrodes and selected ones there-of are electrically energized to pass electric pulses through the layer at selected points to cause point-by-point selective coagula-tion and adherence of the colloid in variable thickness on the positive electrode directly opposi-te each energized negative electrode, thereby forming dots of coagulated colloid representative of a ~ desired image which may be transferred on-to an end-use support, such as paper.
A major problem encountered with such an electrocoagulation prin-ting 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 ;~
23~3 trapped at the interface of the negative electrodes and thus adversely affect the image reproduction. It has been observed tha-t when forming the first series of dots of coagulated colloid there is no such undesirable gas gene-ration and accumulation at the nega-tive electrodes, but after the first electrocoagulation hydrogen generated by electrolysis slowly builds up and creates an electrical resistance at the in-terEace of the negative electrodes su~h as to cause the formation of the dots of coagulated colloid to become erratic.
S~MMARY OF THE INVENTION
It is therefore an object of the present inven-tion to overcome the above drawback and to provide a method of preventing undesirable gas generation between electrodes of, for instance, an electrocoagul-ation printing system.
According to a broad aspect of the invention, there is provided a me-thod of preventing undesirable gas generation between a pair of opposite, electrically ener-gized negative and positive electrodes spaced from one another by a gap filled with an aqueous electrolyte solution, which comprises coating the positive elec-trode with an olefinic substance to form tnicro-droplets thereof on the surface of the positive electrode prior -to electrically energizing the electrodes such that upon electrical ener-gization gas generated as a resul-t oE electrolysis is consumed by reaction with -the olefinic substance, -the reaction being carried out in the presence of a me-tallic oxide catalyst. In this manner, undesirable gas genera-tion between the electrodes is prevented.
, i 3~3 The method of the invention is particularly useful in electrocoagulation printing systems where an image is reproduced by electrocoagulation of an electroly-tically 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 a-t the interface of the negative electrode W~
by the accumulation of hydrogen and~causes an erratic formation of the dots of coagulated colloidlto be suppres-sed.
The present invention therefore also provides, in another aspect thereof, an improved method of reprodu-cing an image by electrocoagulation of an electrolytically coagulable colloid, wherein a layer of an aqueous colloidal dispersion containing an electrolytically coagulable colloidj water and a soluble electrolyte is interposed between a-t least one pair of opposite, electrolytically inert negative and positive electrodes spaced from one another by a gap filled with the aqueous colloidal disper-sion 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 improvemen-t residing in coating -the posi-tive electrode with an olefinic substance to form micro-droplets thereof on the surface of the posi-tive electrode prior to electrically energizing -the electrodes ~ tha-t upon electrical energization hydrogen generated as a result of electrolysis is consumed by reaction wi-th -the olefinic substance, the reaction being carried , . . .
out in the presence of a metallic oxide catalyst, thereby preventin~ undesirable hydrogen generation and accumulation at the negative electrode.
It has been surprisingly found, according to the invention, that by coating the positive electrode with an olefinic substance undesirable hydrogen yeneration and accumulation at the negative electrode is prevented as the hydrogen is consumed by reaction with the olefinic substance, provided that the reaction be carried out in the presence of a metallic oxyde catalyst which is either already present as a surface layer on the positive electrode utilized or is admixed with the olefinic substance. It is believed that the reaction involved ls one of hydrogena-tion whereby the olefinic substance is converted into an ethylenically saturated product.
It is also important that the coating of olefi nic 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 other-wise create an electrical insulation preventing the passage of electric current. Such micro-droplets may have, for instance, a size ranging from about 2 to about 10 ,u.
The micro-droplets of olefinic substance do ' i, not in any way affect the precision or resolu-tion 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.
Examples of suitable olefinic substances which may be used according to the inven-tion include unsatura-ted fatty acids such as arachidonic acid, linoleic acid, linolenic acid, oleic acid and palmi-toleic 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 posi-tive electrode, or it may be liquefied by heat and applied as a liquid.
Since the metal of -the positive electrode is not ea~ily wetted by the unsatura-ted fat-ty acids which are liquid a-t room -tempera-ture, or by -the unsaturated vege-table oils or waxes, micro-drople-ts of the olefinic subs-tance can be readily formed on the surface of the positive electrode by applying the olefinic substance by means of a cloth impregna-ted with the la-t-ter.
:~, ?
It has been observed that when an unsa-turated fatty acid such as linoleic or oleic acid is used as the olefinic substance and where the positive electrode utilized is made of stainless steel having a chromium oxide surface layer, the chromium oxide in the surface layer of the electrode is sufficien-t -to act as the me-tallic oxide ca-talyst for hydrogenating the unsaturated fatty acid to a satura-ted fatty acid.
Thus, no additional metallic oxide ca-talyst is necessary. However, when it is desired to reproduce half--tones, a metallic oxide catalyst is usually admixed with the unsatura-ted fatty acid for obtaining an image reproduc-tion of high quality.
Examples of suitable metallic oxide cata-lysts 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 ca-talys-t.
When the olefinic subs-tance is an unsa--turated vege-table oil, it is advantageously applied to the positive elec-trode in -the form of a dispersion containing -the me-tallic oxide catalyst. The metallic oxide catalyst is preferably presen-t in an amount of about 1 to about 10% by weigh-t, based on -the total weigh-t of the dispersion. Particularly preferred dispersion-~are -those containing abou-t 88 wt.% of an ' :' ~2~38 unsaturated vegetable oil such as olive oil, corn oil or peanut oil, about 2 wt.% of oleic acid and about 10 wt.% of ferric oxide.
The method according to the invention not only prevents undesirable gas generation between electrodes of an electrocoagula-tion 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. Indeed, by using as olefinic substance an unsaturated vegetable oil, the micro-droplets of vegetable oil are converted upon hydrogenation into micro-droplets of fa-t weakening the adherence of the dots of coagulated colloid to the positive electrode and thereby facilitating the transfer of the coagu-lated colloid onto the end-use support upon contact therewith.
After electrocoagulation and transfer of the coagulated colloid on-to an end-use support, the micro-droplets of fat or other ethylenically satu-rated product which remain on the positive electrode can be removed by cleaning the surface of the electrode with an organic solvent such as acetone, Detroleum ether or toluene, or with any commercially available detergent solution.
The following non-limiting examples illus-trate the invention.
~L2~3(~
An elec-trocoagulation printing system according to one of the embodiments described in Applicant's U.S. Patent No. 3,892,6~5 was used. In such an embodiment, a positive electrode in the form oE a revolving cylinder having a cylindrical surface made of stainless steel is pa:rtially immersed in a bath containing an electrolytically coagulahle colloid, water and a soluble electrolyte and main-tained at substantially constant temperature, the stainless steel having a surface layer of chromium oxide. The printing head which is operative to form do-ts of coagulated colloid on the surface of the positive electrode comprises a plurality of electri-cally-insulated juxtaposed negative elec-trodes spaced from the positive electrode surface by a substan-tially constant electrode gap of the order of 50 lu.
Prior to immersing the cylinder into the bath containing -the aqueous coll.oidal dispersion, the cylindrical surface was coated with oleic acid to form thereon micro-droplets of unsaturated fatty acid. After immersion in-to -the ba-th, the oleic acid coated cylinder was set into revolving motion to fill -the elec-trode gap with -the aqueous colloidal disper-sion. Selected ones of the negative electrodes were then electrically energized to cause point-by-point selec-tive coagulation and adherence of the colloid onto the positive electrode surface, thereby forming a series of corresponding dots of coagulated colloid representative of a deisired image.
'' 1 ~`'~1 During -the electrocoagulation, no undesir-able hydrogen generation and accumulation at the negative electrodes could be observed. The resulting dots of coagulated colloid were also easily transfer-rable onto an end-use support, such as paper.
Example 1 was repeated, except that the oleic acid was replaced by linoleic acid. Essential-ly the same results were obtained.
-Example 1 was repeated, excep-t that -the sur-face of -the positive electrode was coa-ted with a dispersion containing about 88 wt.% olive oil, about
2 wt.% oleic acid and about 10 wt.% ferric acid.
Essentially -the same results were obtained.
A conversion of the vege-table oil in-to fat was also observed Example 1 was repeated, excep-t -that the surface of the positive electrode was coa-ted wi-th a dispersion containing abou-t 88 w-t.% corn oil, about 2 wt.% oleic acid and abou-t 10 wt.% ferric oxide.
Essentially -the same results were obtained.
_ Example 1 was repeated, except -tha-t -the surface of the posi-tive electrode was coated with a dispersion containing about 95 wt.% oleic acid and about 5 wt.% ferric oxide. Essentially the same resul-ts were ob-tained.
"' ~' Particularly favorable results were obtained when using as electrolytically coagulable colloid a linear polyacrylamide having a molecular weight of about 250,000 and sold under the trademark ACCOSTRENGTH 86 by Cyanamid Inc.
Moreover, dots of coagulated colloid could be formed at a rate of about 2,000,000 per second, with half-tones being clearly reproduced.
The procedure of example 1 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. Vpon 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.
COMPARATIVE EXAMPI.E 2 The procedure of Example 1 was repeated, except that the surface of the positive electrode was coated with a dispersion containing about 90 wt.%
mineral oil and about 10 wt.% ferric oxide. The same results as in Comparative Example 1 were obtained.
~ 11 -
Essentially -the same results were obtained.
A conversion of the vege-table oil in-to fat was also observed Example 1 was repeated, excep-t -that the surface of the positive electrode was coa-ted wi-th a dispersion containing abou-t 88 w-t.% corn oil, about 2 wt.% oleic acid and abou-t 10 wt.% ferric oxide.
Essentially -the same results were obtained.
_ Example 1 was repeated, except -tha-t -the surface of the posi-tive electrode was coated with a dispersion containing about 95 wt.% oleic acid and about 5 wt.% ferric oxide. Essentially the same resul-ts were ob-tained.
"' ~' Particularly favorable results were obtained when using as electrolytically coagulable colloid a linear polyacrylamide having a molecular weight of about 250,000 and sold under the trademark ACCOSTRENGTH 86 by Cyanamid Inc.
Moreover, dots of coagulated colloid could be formed at a rate of about 2,000,000 per second, with half-tones being clearly reproduced.
The procedure of example 1 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. Vpon 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.
COMPARATIVE EXAMPI.E 2 The procedure of Example 1 was repeated, except that the surface of the positive electrode was coated with a dispersion containing about 90 wt.%
mineral oil and about 10 wt.% ferric oxide. The same results as in Comparative Example 1 were obtained.
~ 11 -
Claims (20)
1. A method of preventing undesirable gas gene-ration 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 said electrodes such that upon electrical energization gas generated as a result of electrolysis is consumed by reaction with said olefinic substance, said reaction being carried out in the presence of a metallic oxide catalyst, thereby preventing undesirable gas genera-tion between said electrodes.
2. A method as claimed in claim 1, wherein said olefinic substance is selected from the group consisting of unsaturated fatty acids, unsaturated vegetable oils and waxes.
3. A method as claimed in claim 2, wherein said olefinic substance is an unsaturated fatty acid selected from the group consisting of arachidonic acid, linoleic acid, linolenic acid, oleic acid and palmitoleic acid.
4. A method as claimed in claim 2, wherein said olefinic substance is an unsaturated vegetable oil selected from the group consisting of corn oil, linseed oil, olive oil, peanut oil and soybean oil.
5. A method as claimed in claim 3, wherein said unsaturated fatty acid is linoleic or oleic acid and wherein said positive electrode is made of stainless steel having a chromium oxide surface layer, said chromium oxide acting as said metallic oxide catalyst.
6. A method as claimed in claim 1, wherein said olefinic substance is an unsaturated vegetable oil and is applied to said positive electrode in the form of a dispersion containing said metallic oxide catalyst.
7. A method as claimed in claim 6, wherein said metallic oxide catalyst is present in an amount of about 1 to about 10% by weight, based on the total weight of said dispersion.
8. A method as claimed in claim 6, wherein said metallic oxide catalyst is selected from the group consisting of aluminum oxide, ceric oxide, chromium oxide, cupric oxide, cuprous oxide, ferric oxide, ferrous oxide, lead oxide, magnesium oxide, manganese oxide and zinc oxide.
9. A method as claimed in claim 8, wherein said dispersion contains about 88 wt.% of an unsaturated vegetable oil selected from the group consisting of olive oil, corn oil and peanut oil, about 2 wt.% of oleic acid and about 10 wt.% of ferric oxide.
10. In a method of reproducing an image by electro-coagulation of an electrolytically coagulable colloid, wherein a layer of an aqueous colloidal dispersion containing an electrolytically coagulable colloid, water and a soluble electrolyte is interposed between at least one pair of opposite, electrolytically inert negative and positive electrodes spaced from one another by a gap filled with said aqueous colloidal dispersion and said 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 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 said electrodes such that upon electrical ener-gization hydrogen generated as a result of electrolysis is consumed by reaction with said olefinic substance, said reaction being carried out in the presence of a metallic oxide catalyst, thereby preventing undesirable hydrogen generation between said electrodes.
11. A method as claimed in claim 10, wherein said olefinic substance is selected from the group consisting of unsaturated fatty acids, unsaturated vegetable oils and waxes.
12. A method as claimed in claim 11, wherein said olefinic substance is an unsaturated fatty acid selected from the group consisting of arachidonic acid, linoleic acid, linolenic acid, oleic acid and palmitoleic acid.
13. A method as claimed in claim 11, wherein said olefinic substance is an unsaturated vegetable oil selected from the group consisting of corn oil, linseed oil, olive oil, peanut oil and soybean oil.
14. A method as claimed in claim 12, wherein said unsaturated fatty acid is linoleic or oleic acid and wherein said positive electrode is made of stainless steel having a chromium oxide surface layer, said chromium oxide acting as said metallic oxide catalyst.
15. A method as claimed in claim 10, wherein said olefinic substance is an unsaturated vegetable oil and is applied to said positive electrode in the form of a disper-sion containing said metallic oxide catalyst.
16. A method as claimed in claim 15, wherein said metallic oxide catalyst is present in an amount of about 1 to about 10% by weight, based on the total weight of said dispersion.
17. A method as claimed in claim 15, wherein said metallic oxide catalyst is selected from the group consisting of aluminum oxide, ceric oxide, chromium oxide, cupric oxide, cuprous oxide, ferric oxide, ferrous oxide, lead oxide, magnesium oxide, manganese oxide and zinc oxide.
18. A method as claimed in claim 17, wherein said dispersion contains about 88 wt.% of an unsaturated vegetable oil selected from the group consisting of olive oil, corn oil and peanut oil, about 2 wt.% of oleic acid and about 10 wt.% of ferric oxide.
19. A method as claimed in claim 10, wherein said dots of coagulated colloid are contacted with an end-use support to cause transfer of the coagulated colloid onto said end-use support and thereby imprint said end-use support with said image, and wherein said olefinic substance is an unsaturated vegetable oil such that upon reaction the micro-droplets of vegetable oil are converted into micro-droplets of fat weakening the adherence of said dots of coagulated colloid to said positive electrode and thereby facilitating the transfer of said coagulated colloid onto said end-use support upon contact therewith.
20. A method as claimed in claim 12, wherein said positive electrode is made of stainless steel having a chromium oxide surface layer, and wherein said unsaturated fatty acid is oleic acid and is applied in the form of a dispersion containing ferric oxide as said metallic oxide catalyst, said electrolytically coagulable colloid comprising a linear polyacrylamide having a molecular weight of about 250,000.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000514197A CA1249238A (en) | 1986-07-18 | 1986-07-18 | Method of preventing undesirable gas generation between electrodes of an electrocoagulation printing system |
| DE8787110136T DE3771007D1 (en) | 1986-07-18 | 1987-07-14 | METHOD FOR PREVENTING UNWANTED GAS GENERATION BETWEEN ELECTRODES OF AN ELECTROCOAGULATION PRESSURE SYSTEM. |
| AT87110136T ATE64716T1 (en) | 1986-07-18 | 1987-07-14 | PROCEDURE TO PREVENT UNDESIRABLE GAS GENERATION BETWEEN ELECTRODES OF AN ELECTROCOAGULATION PRESSURE SYSTEM. |
| EP87110136A EP0253358B1 (en) | 1986-07-18 | 1987-07-14 | Method of preventing undesirable gas generation between electrodes of an electroco-agulation printing system |
| JP62177363A JPH0710618B2 (en) | 1986-07-18 | 1987-07-17 | Method for preventing unnecessary gas generation between electrodes in electrocoagulation printing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000514197A CA1249238A (en) | 1986-07-18 | 1986-07-18 | Method of preventing undesirable gas generation between electrodes of an electrocoagulation printing system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1249238A true CA1249238A (en) | 1989-01-24 |
Family
ID=4133599
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000514197A Expired CA1249238A (en) | 1986-07-18 | 1986-07-18 | Method of preventing undesirable gas generation between electrodes of an electrocoagulation printing system |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0253358B1 (en) |
| JP (1) | JPH0710618B2 (en) |
| AT (1) | ATE64716T1 (en) |
| CA (1) | CA1249238A (en) |
| DE (1) | DE3771007D1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3067771B1 (en) * | 1999-07-12 | 2000-07-24 | ヤマハ株式会社 | Printing equipment |
Family Cites Families (6)
| 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 (en) * | 1984-05-11 | 1989-02-21 | Adrien Castegnier | Printing method by electrolytic colloid coagulation and colloid composition therefor |
| CA1205778A (en) * | 1984-05-16 | 1986-06-10 | Adrien Castegnier | Image reproduction by in plane electro-coagulation of a colloid |
| US4555320A (en) * | 1984-05-25 | 1985-11-26 | Elcorsy Inc. | Image reproduction by in plane electro-coagulation of a colloid |
| CA1279603C (en) * | 1986-02-20 | 1991-01-29 | Adrien Castegnier | Monochromic and polychromic printing of an image reproduced by electro-coagulation of a colloid |
-
1986
- 1986-07-18 CA CA000514197A patent/CA1249238A/en not_active Expired
-
1987
- 1987-07-14 EP EP87110136A patent/EP0253358B1/en not_active Expired - Lifetime
- 1987-07-14 DE DE8787110136T patent/DE3771007D1/en not_active Expired - Lifetime
- 1987-07-14 AT AT87110136T patent/ATE64716T1/en not_active IP Right Cessation
- 1987-07-17 JP JP62177363A patent/JPH0710618B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0253358B1 (en) | 1991-06-26 |
| EP0253358A2 (en) | 1988-01-20 |
| DE3771007D1 (en) | 1991-08-01 |
| JPS6331784A (en) | 1988-02-10 |
| JPH0710618B2 (en) | 1995-02-08 |
| ATE64716T1 (en) | 1991-07-15 |
| EP0253358A3 (en) | 1988-12-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |