JP2000033727A - Anode surface coating agent for electric coagulation printing and electric coagulation printing method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anode surface coating agent not increasing the viscosity of electric coagulation printing ink during printing and not bringing about back staining undesirable to the non-image part of a material to be printed and an electric coagulation printing method capable of forming electric coagulation printed matter free from the lowering of image quality caused by back staining. SOLUTION: A process preparing an anode surface coating agent for electric coagulation printing containing isostearic acid, an anode having a passive surface and a cathode, a process coating the surface of an anode with liquid microdroplets of the anode surface coating agent for electric coagulation printing containing isostearic acid, a process forming dots of coagulated ink corresponding to a desired image on the surface of the anode by the electric coagulation of printing ink containing an electrolytically coagulable polymer charged in the gap between the anode and the cathode and a process transferring the dots of the coagulated ink to a material to be printed to form an image are included.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvements in the field of electrocoagulation printing, and in particular, does not increase the viscosity of an electrocoagulation printing ink even when mixed with the ink in a printing process, so that a non-image area of a printed matter is not increased. Undesired dirt (ground dirt)
The present invention relates to an improved anode surface coating agent for electrocoagulation printing which does not cause bleeding, and an electrocoagulation printing method using the same.

[0002]

2. Description of the Related Art Electrocoagulation printing is a printing method which does not require a plate at all so that a printed matter can be directly obtained by a digital image signal from a computer. Conventional printing methods such as offset printing, letterpress printing, screen printing, Unlike gravure printing and the like, steps such as plate production and plate change are not required, so that the time required for the printing operation is short. In addition, since this printing method can use a water-based ink, compared to the printing method using an oil-based ink, air pollution,
It is excellent in terms of fire danger, work safety and health.

An electrocoagulation printing method and apparatus are disclosed in US Pat. No. 4,895,629 (registered date: 1990).
No. 5,538,601 (Registration date: 1)
No. 5,693,206 (registration date: December 2, 1997). In the electrocoagulation printing method, after the anode surface is washed, an oily substance is applied to the anode surface, and an image is formed by electrocoagulation of a printing ink (electrocoagulation printing ink) containing a polymer that can be electrolytically coagulated on the surface. Coagulated ink dots are formed, the uncoagulated electrocoagulated printing ink remaining on the anode surface, i.e. the non-coagulated ink, is removed, and the exposed coagulated ink dots are transferred to the substrate, whereby the substrate is printed. The image is printed.

An electrocoagulation printing apparatus includes an anode having a passive surface, an anode surface cleaning means, an oily substance application means, an electrocoagulation printing ink supply means, a plurality of cathodes arranged at a fixed distance from the anode, It has a means for removing solidified ink, and means for transferring dots of solidified ink on the anode to the printing medium.

As described in the above-mentioned US patent, an oily substance is used for the purpose of weakening the adhesion of the coagulating ink to the anode and preventing corrosion of the anode, and is applied to the anode surface by an oily substance application means. You. Non-coagulated ink remaining after the electro-coagulation of the electro-coagulated printing ink is removed from the anode surface by means of non-coagulated ink removing means, for example, by rubbing the anode surface with a soft rubber squeegee, and supplied to the electro-coagulated printing ink supply means. It is reused by returning. When oleic acid or oleic acid containing chromium oxide is used as the oily substance, the viscosity of the electrocoagulated printing ink increases after printing for about 1 hour. When the viscosity of the electrocoagulation printing ink increases, it becomes difficult to supply the ink by the electrocoagulation printing ink supply means, and it is necessary to frequently adjust the ink to prevent the image portion from being lost due to a decrease in the supply amount of the electrocoagulation printing ink. The problem is that it is difficult to completely remove the non-coagulated ink from the anode surface with a soft rubber squeegee, and the non-coagulated ink remaining on the anode surface causes undesired stains on the non-image area, that is, background stains. Was causing the problem of decline.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to overcome the above-mentioned disadvantages which cannot be solved by existing oily substances based on the prior art. That is, it does not increase the viscosity of the electrocoagulated printing ink during printing and does not cause undesired background stain on the non-image area of the printing medium. It is an object of the present invention to provide an electrocoagulation printing method capable of producing an electrocoagulated printed matter without any problem.

[0007]

Means for Solving the Problems The present inventors have developed a non-solidified ink which has been removed from the anode surface by rubbing the anode surface with a soft rubber squeegee or the like. It has been confirmed that a coating agent is included, and as the electrocoagulation printing time becomes longer, the anode surface coating agent for electrocoagulation printing is gradually mixed into the electrocoagulation printing ink to increase its concentration. For example, when printing is performed for about 1 hour using oleic acid as an anode surface coating agent for electrocoagulation printing, the electrocoagulation printing ink after printing is completed contains about 0.2% by weight of oleic acid. It has been confirmed that when oleic acid is mixed in the coagulated printing ink, the viscosity of the ink is remarkably increased, and the same applies to other unsaturated fatty acids. It is considered that this phenomenon occurs because the dispersion of the pigment in the ink becomes unstable when oleic acid is mixed into the electrocoagulated printing ink. The inventors of the present invention have conducted intensive studies in view of the above-mentioned situation, and as a result, have found that isostearic acid does not increase the viscosity of an electrocoagulated printing ink even when mixed into the ink, resulting in the present invention.

That is, the present invention relates to an anode surface coating agent for electrocoagulation printing containing isostearic acid. The present invention also relates to an electrocoagulation printing method comprising the steps of: (a) providing an anode having a passive surface and a cathode; (b) an anode for electrocoagulation printing, wherein the anode surface comprises isostearic acid. Coating with a microdroplet of a surface coating agent; (c) forming a dot of the coagulated ink corresponding to a desired image by electrocoagulation of a printing ink containing an electrocoagulable polymer filled between the negative and positive electrodes; And (d) forming an image on the printing medium by transferring the dots of the solidified ink to the printing medium.

[0009]

Next, the anode surface coating agent for electrocoagulation printing of the present invention will be described in detail. Note that the term “coating agent” used in the following description represents “anode surface coating agent for electrocoagulation printing”. Isostearic acid used in the coating agent of the present invention is a compound represented by the chemical formula (1).

The amount of isostearic acid is preferably 40 to 100% by weight based on the total weight of the coating agent. When the amount of isostearic acid is less than 40% by weight, adverse effects such as insufficient fluidity of the coating and an increase in the viscosity of the electrocoagulated printing ink are caused by raw materials other than isostearic acid used in the coating. Tend. The coating agent of the present invention polish the anode surface,
Alternatively, for the purpose of adjusting the coating agent to an appropriate viscosity, an inorganic filler or the like can be further contained.

Examples of the inorganic filler include aluminum oxide, cerium dioxide, chromium (III) oxide, cuprous oxide, cupric oxide, ferrous oxide, ferric oxide, lead oxide,
Examples include magnesium oxide, manganese (III) oxide, titanium dioxide, zinc oxide, barium sulfate, calcium carbonate, and silicon dioxide (silica). The silicon dioxide preferably has a specific surface area of 100 to 600 m ² / g as measured by the BET method (nitrogen absorption method). The inorganic fillers can be used alone or in combination of two or more.

The compounding amount of the inorganic filler is an amount for appropriately polishing the anode surface or an amount for adjusting the coating agent to an appropriate viscosity. Specifically, about 1 to 5 parts by weight based on the total weight of the coating agent.
It is preferably 0% by weight. In order to stably disperse the inorganic filler in the coating agent of the present invention, a dispersant can be used. As a dispersant, anionic, nonionic,
Cationic or zwitterionic surfactants and the like can be used.

The coating composition of the present invention may contain an unsaturated fatty acid for the purpose of further reducing the adhesion of the coagulated ink to the dots of the anode. However, since unsaturated fatty acids have the effect of increasing the viscosity of the electrocoagulated printing ink, the amount of the unsaturated fatty acids is preferably not more than 30% by weight, particularly preferably not more than 20% by weight, based on the total weight of the coating agent. It is. Examples of unsaturated fatty acids include arachidonic acid, oleic acid,
Linoleic acid, linoleic acid, palmitoleic acid, myristooleic acid and the like can be mentioned. Further, the coating agent of the present invention comprises unsaturated vegetable oils containing triglycerides of unsaturated fatty acids as a main component, such as corn oil, linseed oil, olive oil, peanut oil, sunflower oil, soybean oil, and carnauba wax. Saturated vegetable waxes and the like can also be included. Unsaturated fatty acids, unsaturated vegetable oils, and unsaturated vegetable waxes can be used alone or as a mixture of two or more.

The coating of the present invention preferably has a surface tension at 20 ° C. of not more than 40 mN / m, and is generally about 15 mN / m.
mN / m or more. The surface tension of the coating agent is 40 mN / m
When the ratio exceeds the above range, it tends to be difficult to sufficiently coat the anode surface with the microdroplets of the coating agent. The surface tension of the coating agent can be adjusted by appropriately selecting the raw materials to be used. Further, the viscosity of the coating agent of the present invention is appropriately adjusted within a range that does not adversely affect electrocoagulation printing by using a higher alcohol, a thickener obtained by modifying dextrin to make it oil-soluble, an oil-soluble polymer material, or the like. Can be adjusted.

When the viscosity of the raw materials used is low, the coating agent of the present invention can be produced by simply stirring and mixing using a mixer or the like. When the viscosity of the raw material is high, it can be produced by heating and dissolving as necessary and stirring and mixing using a mixer or the like.
When the inorganic filler is blended with the coating agent, it can be produced by a mixer, but it is preferable to use an disperser to atomize the inorganic filler. As the disperser, a generally used roller mill, ball mill, pebble mill, attritor, sand mill, or the like can be used.

The coating agent containing an inorganic filler having a desired particle size distribution may be appropriately adjusted for dispersion conditions, for example, the size of the pulverizing media of the disperser, the filling rate of the pulverizing media, the dispersion treatment time, the discharge speed, the viscosity of the coating agent, and the like. It can be obtained by adjusting. The maximum particle size of the inorganic filler dispersed in the coating agent is preferably 10 μm or less, more preferably 5 μm or less. When coarse particles and the like are unexpectedly mixed in the coating material of the present invention, it is preferable to remove coarse particles and the like by filtration or the like in order to prevent electrocoagulation of a printing ink containing a polymer that can be electrolytically coagulated and reduce image quality. . As the filtration device, any conventionally known device using a gravity, reduced pressure, pressure type filter or centrifugal separation can be used.

Next, the electrocoagulation printing method of the present invention will be described. The electrocoagulation printing method of the present invention includes the following steps (a) to (d): (a) preparing an anode having a passive surface, and a cathode; (b) including an isostearic acid on the anode surface. (C) a coagulation ink corresponding to a desired image by electrocoagulation of a printing ink containing an electrocoagulable polymer filled between the negative and positive electrodes; Forming dots on the surface of the anode; and (d) forming an image on the printing medium by transferring the dots of the coagulated ink to the printing medium.

More preferably, the electrocoagulation printing method of the present invention comprises the following steps (1) to (7): (1) preparing an anode having a passive surface and a cathode; (2) anode Washing the surface; (3) coating the anode surface with microdroplets of an anode surface coating agent for electrocoagulation printing containing isostearic acid; (4) printing ink containing a polymer capable of electrolytic coagulation between the negative and positive electrodes. (5) applying a voltage to the selected cathode corresponding to the desired image to form dots of the coagulated ink on the anode surface coated with microdroplets of the anode surface coating agent for electrocoagulation printing. A step of forming; (6) a step of removing the uncoagulated electrocoagulated printing ink, that is, a non-coagulated ink from the anode surface; and (7) transferring dots of the coagulated ink formed on the anode surface to the printing medium. This And forming a desired image on the printing medium.

As used herein, the expression "electrocoagulation of a printing ink containing an electrocoagulable polymer" is applied to steps (c) and (5) of the above-described process, in which a voltage is applied to a cathode. Polyvalent metal ions are eluted from the anode surface due to the destruction of the passivation film on the anode surface, and the printing ink is solidified by the chemical bond between the polyvalent metal ions and the polymer that can be electrolytically solidified contained in the printing ink. It means that dots of solidified ink are formed on the top. The polyvalent metal ion eluted from the anode surface is, for example, trivalent iron or trivalent aluminum ion when an anode made of stainless steel or aluminum is used for the electrocoagulation printing method.

The electrocoagulated printing ink contains at least a polymer which can be electrolytically coagulated, a colorant, a soluble electrolyte, and a liquid medium, and preferably further contains a sequestering agent. The polymer capable of electrolytic coagulation is a polymer capable of chemically bonding to a polyvalent metal ion, and preferably has a functional group such as an amide group, an amino group, and a carboxyl group. As the colorant, pigments and dyes used in general printing inks, paints, recording agents, and the like can be used. When the colorant is a pigment, a dispersant can be used to stably disperse the pigment in a liquid medium. A halide can be used as a soluble electrolyte, water can be used as a liquid medium, and polyaminocarboxylic acid and salts thereof can be used as a sequestering agent.

FIG. 1 shows an outline of an electrocoagulation printing apparatus 1 for performing printing using the anode surface coating agent for electrocoagulation printing of the present invention. In the electrocoagulation printing apparatus 1, a base plate 5 is erected by a plurality of feet 3, and a plurality of frames 7 are erected on the base plate 5 so as to extend in a vertical direction. A pair of vertical plates 9 are provided on the upper part of the frame 7, and each vertical plate 9 holds a rotatable cylindrical anode 11 by a drive motor (not shown). The anode 11 is stretched in the direction perpendicular to the paper of FIG. 1 and has an anode surface having a passivation film.

The electrocoagulation printing apparatus 1 includes an anode 11
Coating means 13 for applying the coating material of the present invention to the anode surface along
And an electrocoagulation printing ink supply means 15 having a temperature control means (not shown) for supplying the electrocoagulation printing ink to the anode.
And a print head 19 having a cathode 17 for forming a plurality of dots of coagulated ink on the anode surface representing the desired image by electrocoagulation of a printing ink comprising an electrocoagulable polymer, A non-coagulated ink removing means 21 such as a squeegee for removing ink from the anode surface is provided. Then, the plurality of dots of the coagulated ink representing a desired image on the obtained anode surface are brought into contact with the printing medium W, and the dots of the coagulated ink are transferred from the anode surface to the printing medium, whereby An impression cylinder 23 is provided as means for printing the image on the printing medium.

Further, below the anode 11, an anode provided with a temperature control means (not shown) for removing the coagulated ink, non-coagulated ink, coating agent and the like remaining on the anode surface by washing the same from the anode surface. A surface cleaning means 25 is provided.
With such a configuration, after the microdroplets of the coating agent of the present invention are applied to the anode surface of the rotating anode 11 by the coating agent application unit 13, the electrocoagulation printing ink supply unit 1 is applied.
5 supplies the electrocoagulated printing ink between the cathode 17 and the anode 11 located at a certain distance. The supplied ink forms dots of coagulated ink by applying a voltage between the negative and positive electrodes, and the non-coagulated ink forms a squeegee 21.
From the anode surface.

Next, the dots of the coagulated ink formed on the anode surface are transferred between the anode 11 and the impression cylinder 23 by the printing medium W.
Is transferred to and printed on the printing medium W by contact with the dots of the solidified ink. Multicolor printing can be realized by preparing a desired number of the electrocoagulation printing apparatuses 1 shown in FIG. 1 and successively printing electrocoagulation printing ink having a desired hue in each electrocoagulation printing apparatus. For example, process printing can be performed by arranging four electrocoagulation printing apparatuses 1 shown in FIG. 1 in tandem and printing yellow, indigo, red, and black ink successively in each apparatus.

An electrocoagulation printing apparatus for printing using the coating agent of the present invention is described in US Pat.
No. 538,601 (registration date: July 23, 1996) may be a center drum type printing apparatus. This printing method does not require a printing unit including an anode surface cleaning unit, a coating agent applying unit, an electrocoagulated printing ink supply unit, a plurality of cathodes located at a fixed distance from the anode, a non-coagulated ink removing unit, and a transfer unit. Fig. 4 is a system arranged around a single rotating anode in the shape of a cylinder with a moving surface. For example, four printing units are arranged around a single anode, with each printing unit yellow, indigo,
By sequentially printing red and black inks sequentially, process printing becomes possible.

[0026]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples unless it departs from the technical idea of the present invention. In the examples, the pH is a glass electrode type hydrogen ion concentration meter manufactured by Electrochemical Instruments, the viscosity is a B-type viscometer manufactured by Tokimec, and the surface tension is an automatic surface tension meter CBVP-Z manufactured by Kyowa Interface Science Co., Ltd.
It measured using each. The pH was measured at 25 ° C., the viscosity was measured at 30 ° C., and the surface tension was measured at 20 ° C.
Also, the reflection density of the printed matter is X-Rit manufactured by X-Rite.
The measurement was performed using e (registered trademark) MODEL408.

(Production Example 1) Black ink for electrocoagulation printing was
Manufactured from the following raw materials: -Carbon black pigment 8.8% by weight ("Carbon Black Monarch 120": Cabot Corporation)-Anionic dispersant aqueous solution (active ingredient about 42% by weight) 0.75% by weight ("CLOSPERSE 2500": Baume Filexate -Anionic acrylamide polymer 8.8% by weight ("ACCOSTEWNGTH 86": Mitsui Cytec)-Potassium chloride (soluble electrolyte) 8.8% by weight-Disodium EDTA dihydrate (sequestering agent) 03% by weight-water (liquid medium) 72.82% by weight Total 100% by weight First, a pigment dispersion containing a pigment, a dispersant, and water is produced using a sand mill (dispersing machine), and then the pigment is dispersed. An acrylamide polymer was added to the dispersion, and potassium chloride and a sequestering agent were further mixed, followed by filtration and defoaming to produce a black ink for electrocoagulation printing. PH of the ink
Was about 4.1 and the viscosity was about 470 cps.

(Production Example 2) Yellow ink for electrocoagulation printing was
The black ink of Production Example 1 was produced from the following raw materials in the same manner. -Azo-based yellow pigment 11.75% by weight ("Permanent Yellow DGR pigment": Clariant)-Anionic dispersant aqueous solution (about 42% by weight of active ingredient) 4.2% by weight ("CLOSPERSE 2500": Baume Filexatex) -Canada)-Anionic acrylamide polymer 7.0% by weight ("ACCOSTEWNGTH 86": Mitsui Cytec)-Potassium chloride (soluble electrolyte) 8.4% by weight-Disodium EDTA dihydrate (sequestering agent) 0 0.03% by weight-water (liquid medium) 68.62% by weight Total 100% by weight The obtained yellow ink for electrocoagulation printing had a pH of about 4.1 and a viscosity of about 470 cps.

(Production Example 3) Azo yellow pigment is 10.5% by weight of azo red pigment ("Permanent Rubin F6B": Clariant) and water is 69.87% by weight.
A red ink for electrocoagulation printing was produced using the same raw materials and method as in Production Example 2 except that the above was replaced. The pH of the ink was about 4.1 and the viscosity was about 480 cps.

(Production Example 4) Copper-phthalocyanine pigment ("Heliogen Blue D707") was used as an azo red pigment.
Indigo ink for electrocoagulation printing was produced using the same raw materials and method as in Production Example 3 except that 2DD was replaced by BASF. The pH of the ink is about 4.1 and the viscosity is about 490 cp
s.

Example 1 Isostearic acid (viscosity: 2
0 cps, surface tension: 25.8 mN / m) was used as a coating in the electrocoagulation printing apparatus shown in FIG. 1 of the type described in U.S. Pat. No. 5,693,206.
The printing device includes an anode made of stainless steel, a device for cleaning the anode with high-pressure water containing a detergent, a device for forming micro droplets of a coating agent on the surface of the anode, an electrocoagulation printing ink supply device, and a fixed distance from the anode. Approximately 5 diameters spaced apart
It comprises a plurality of cathodes of 0 micrometers, a device for removing non-coagulated ink from the anode surface with a soft polyurethane squeegee, and a polyurethane impression cylinder. The electrocoagulated printing ink, the cleaning liquid used in the device for cleaning the anode, and the surface of the anode were heated to 40 ° C. The black ink of Production Example 1 was used as the electrocoagulation printing ink. When the liquid level of the electrocoagulated printing ink in the electrocoagulated printing ink supply device dropped, the ink was added to keep the liquid level constant.
The viscosity of the electrocoagulated printing ink does not increase significantly during printing, and the viscosity of the ink after printing for about 2 hours is 700 cps.
Met. The reflection density of the non-image portion of the printing medium was 0.02, and the printed matter was of good quality. The reflection density of the coagulated ink transferred to the printing medium was 1.31. Further, using the yellow, red, and indigo inks obtained in Production Examples 2 and 3 as electrocoagulation printing inks, printing was performed using the electrocoagulation printing apparatus described above. The viscosity of the yellow, red, and indigo inks did not increase significantly during printing, and the viscosities of the inks after printing for about 2 hours were 680, 710, and 700 cps, respectively. The reflection density of the non-image portion of the printing medium is 0.02,
The prints were of good quality. The reflection densities of the coagulated ink transferred to the printing medium are 1.2, 1.27,
1.27. In addition, the black ink obtained in Production Examples 1 to 4,
0.5% by weight of the coating agent of this example was mixed with indigo, red and yellow inks, sealed and stored at 40 ° C. for 24 hours, and the viscosity of the ink was measured. The viscosity was 700, 680 and 7 respectively.
00, 690 cps, and there was no significant increase in the viscosity of the ink.

Example 2 93% by weight of isostearic acid, silica ("FK500LS": Degussa)
sa), a coating agent containing 7% by weight of BET surface area: about 450 m ² / g) was mixed using a sand mill (dispersion machine).
Manufactured by dispersing. The viscosity of the obtained coating agent was 2000 cps. The surface tension could not be measured accurately due to the high viscosity. Using the coating agent and the black ink of Production Example 1 as the electrocoagulation printing ink, printing was performed under the same conditions and method as in Example 1. The viscosity of the electrocoagulated printing ink did not increase significantly during printing, and the viscosity of the ink after printing for about 2 hours was 690 cps.
The reflection density of the non-image portion of the printing medium was 0.02, and the printed matter was of good quality. The reflection density of the coagulated ink transferred to the printing medium was 1.32. Further, 0.5% by weight of the coating agent of this example was mixed with the black ink for electrocoagulation printing of Production Example 1, sealed, stored at 40 ° C. for 24 hours, and the viscosity of the ink was measured to be 690 cps. There was no significant increase in ink viscosity.

Example 3 75% by weight of isostearic acid
And a coating containing 25% by weight of chromium oxide (dichromium trioxide: American Chromium Chemical Co., Ltd.) using a sand mill (dispersing machine) to produce a coating. The viscosity of the obtained coating agent was 580 cps.
The surface tension could not be measured accurately due to the high viscosity. Printing was performed under the same conditions and method as in Example 2 except that the coating agent was used. The viscosity of the electrocoagulated printing ink did not increase significantly during printing, and the viscosity of the ink after printing for about 2 hours was 690 cps. The reflection density of the non-image portion of the printing medium was 0.02, and the printed matter was of good quality. The reflection density of the coagulated ink transferred to the printing medium was 1.32. Further, the black ink for electrocoagulation printing of Production Example 1 was mixed with 0.5% by weight of the coating agent of the present example, sealed and stored at 40 ° C. for 24 hours, and the viscosity of the ink was measured to be 680 cps. There was no significant increase in ink viscosity.

Example 4 80% by weight of isostearic acid
And oleic acid (viscosity: 20 cps, surface tension: 22.
8mN / m) to obtain a coating. The viscosity and surface tension of the obtained coating agent were 20 cps and 26.1 mN / m, respectively. Printing was performed under the same conditions and method as in Example 2 except that the coating agent was used. After printing for about 2 hours, the viscosity of the electrocoagulated printing ink slightly increased to 950 cps, but the reflection density of the non-image area of the printing medium was 0.03, and the printed matter was of relatively good quality. Was. The reflection density of the coagulated ink transferred to the printing medium was 1.32. Further, the black ink for electrocoagulation printing of Production Example 1 was mixed with 0.5% by weight of the coating agent of the present example, sealed, stored at 40 ° C. for 24 hours, and the viscosity of the ink was measured to be 900 cps. The viscosity of the ink slightly increased.

Example 5 A sand mill (dispersion machine) was used to prepare a coating composition containing 50% by weight of isostearic acid, 15% by weight of oleic acid, and 35% by weight of chromium oxide (dichromium trioxide: American Chromium Chemical Co.). It was manufactured by mixing and dispersing using. The viscosity of the obtained coating agent was 1250 cps. The surface tension could not be measured accurately due to the high viscosity. Printing was performed under the same conditions and method as in Example 2 except that the coating agent was used. The viscosity of the electrocoagulated printing ink after printing for about 2 hours is
It was 800 cps. The reflection density of the non-image portion of the printing medium was 0.02, and the printed matter was of good quality. The reflection density of the coagulated ink transferred to the printing medium was 1.33. Further, the black ink for electrocoagulation printing of Production Example 1 was mixed with 0.5% by weight of the coating agent of this example, and the mixture was sealed and closed.
After storage at 24 ° C. for 24 hours, the viscosity of the ink was measured to be 780 cps, and there was no significant increase in the viscosity of the ink.

Comparative Example 1 Printing was carried out under the same conditions and method as in Example 2 except that oleic acid (viscosity: 20 cps, surface tension: 22.8 mN / m) was used as a coating agent. The viscosity of the electrocoagulated printing ink gradually increased from the start of printing, and increased to 2500 cps after printing for about 2 hours, and increased remarkably. The reflection density of the non-image portion of the printing medium is 0.0
6 and the quality of the obtained printed matter was inferior. The reflection density of the coagulated ink transferred to the printing medium was 1.33. Also, 0.5% by weight of the coating agent of the present example was mixed with the black ink for electrocoagulation printing of Production Example 1, and the mixture was closed and sealed at 40 ° C.
After storage for 24 hours, the viscosity of the ink was measured.
00 cps and the viscosity of the ink increased significantly.

Comparative Example 2 Printing was performed under the same conditions and method as in Example 2 except that caprylic acid (viscosity: 5 cps, surface tension: 28.3 mN / m) was used as a coating agent. The viscosity of the electrocoagulated printing ink gradually increased from the start of printing, and increased to 3000 cps after printing for about 2 hours, and increased remarkably. The reflection density of the non-image portion of the printing medium is 0.0
9, and the quality of the obtained printed matter was inferior. The reflection density of the coagulated ink transferred to the printing medium was 1.33. Also, 0.5% by weight of the coating agent of the present example was mixed with the black ink for electrocoagulation printing of Production Example 1, and the mixture was closed and sealed at 40 ° C.
After storage for 24 hours, the viscosity of the ink was measured.
00 cps and the viscosity of the ink increased significantly.

[0038]

According to the present invention, a coating agent which does not increase the viscosity of the electrocoagulated printing ink during printing can be provided. ADVANTAGE OF THE INVENTION According to this invention, it became possible to stably obtain a print of good quality in which background contamination does not occur in the print even if the print time is long.

[0039]

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an electrocoagulation printing apparatus using the electrocoagulation printing ink of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrocoagulation printing apparatus 3 Foot 5 Base plate 7 Frame 9 Vertical plate 11 Anode 13 Anode surface coating agent application means for electrocoagulation printing 15 Electrocoagulation printing ink supply means 17 Cathode 19 Printing head 21 Non-coagulation ink removing means 23 Impression cylinder 25 Anode surface cleaning means 27 Guide roller W Printed material

Continued on the front page F term (reference) 2C162 AE25 AE68 AE76 AH57 CA03 2H086 AA11 AA49 4J039 AD12 BC19 BE01 BE02 BE22 BE28 CA03 GA34

Claims (4)

[Claims] An anode surface coating for electrocoagulation printing comprising isostearic acid. 2. The anode surface coating composition for electrocoagulation printing according to claim 1, wherein isostearic acid is contained in an amount of 40 to 100% by weight based on the total weight of the anode surface coating composition. 3. The anode surface coating agent for electrocoagulation printing according to claim 1, wherein the surface tension at 20 ° C. is 40 mN / m or less. 4. An electrocoagulation printing method comprising the steps of: (a) providing an anode having a passive surface and a cathode; and (b) coating the anode surface with an isostearic acid for an electrocoagulation printing anode. (C) electrocoagulating a printing ink containing an electrocoagulable polymer filled between the negative and positive electrodes to form dots of coagulated ink corresponding to a desired image on the anode surface. And (d) forming an image on the printing medium by transferring the dots of the solidified ink to the printing medium.