JPH11129550A - Multicolor electric solidification printer and printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multicolor electric solidification printer producing a multicolor image having high clearness. SOLUTION: The multicolor electric solidification printer comprises an anode 20 having an anode active surface movable at a specified speed, a nonexpansive endless belt 26 having a surface 28 movable at same speed as the anode active surface while holding dots of electric solidification colloid separably, a plurality of print units 22A-22D (22), and a transfer unit 42 for bringing a paper web 44 into contact with be colloid holding surface 28 wherein each print unit 22 comprises means 54, 58, 62, 64 for forming a dot of color solidification colloid on the anode active surface, and a press roller 66 for transferring the dot onto the colloid holding surface by bringing the belt 26 into contact with the anode active surface. A plurality of color images of different solidification colloid are superposed on the colloid holding surface passing through the plurality of print units sequentially to form a multicolor image which is then printed onto a basic body by means of the transfer unit 42.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to improvements in the technical field of dynamic printing. More particularly, the present invention relates to an improved multicolor electrocoagulation printing method and apparatus.

[0002]

2. Description of the Prior Art U.S. Pat.
In U.S. Pat. No. 538,601, we use one electrolytically inert anode in the form of a rotating cylinder having a passive surface on which dots of a colored coagulated colloidal representation of an image are made. A multicolor electrocoagulation printing method and apparatus has been described. These dots of colored coagulated colloid then contact a substrate, such as paper, causing transfer of the colored coagulated colloid onto the substrate, thereby printing an image on the substrate. As described in this patent, prior to the application of a voltage to the cathode, the anode is treated with an olefinic material and to reduce the adhesion of the solidified colloid dots to the anode and also to prevent uncontrolled corrosion of the anode. It is coated with a dispersion containing a metal oxide. Furthermore, the gas resulting from the electrolysis when a voltage is applied to the cathode is consumed by the reaction with the olefinic substance, so that no gas accumulation occurs between the cathode and the anode.

[0003] The electrocoagulated printing ink supplied in the gap defined between the anode and the cathode is essentially a solution or solution containing an electrolytically coagulable polymer, a liquid medium, a soluble electrolyte and a colorant. Consists of a dispersion. When the coloring agent used is a pigment, a dispersing agent is added to uniformly disperse the pigment in the ink. After coagulation of the ink, any remaining non-coagulated ink is removed from the surface of the anode, for example by rubbing the surface with a soft rubber squeegee, so that the colored coagulated ink which is subsequently transferred onto the substrate is completely exposed. To be done. Thereafter, the surface of the anode is cleaned using, for example, a plurality of rotating brushes and a cleaning liquid to remove any remaining coagulated ink and oily substances adhered to the surface of the anode.

[0004]

For the purpose of providing a multicolor image, a cathode, an anode coating device, an ink injector, a rubber squeegee, and an anode cleaning device are arranged to define one printing unit, each having a different color. Printing units using different colorants are arranged around the cylindrical anode in order to form several different colored images of the coagulated colloid. Several colored images with different coagulated colloids are transferred from the anodic active surface onto a substrate at each transfer station, superimposed to give the desired multicolor image. Substrates in the form of a continuous web are partially wrapped around the anode and passed through respective transfer stations such that different colored images are printed in superimposition.

However, the paper web is pressed by a rotating cylindrical anode into contact with the dots of the colored coagulated colloid formed by each printing unit, so that different colored images of the coagulated colloid are printed. It is pressed against the anode active surface by a roller. For this reason,
The web is often moved between the anode and the pressure roller in a direction parallel to the longitudinal axis of the anode. Therefore, it is difficult to provide a multicolor image in which different colored images are completely superimposed.

It is an object of the present invention to provide an improved multicolor electrocoagulation printing method and apparatus which can overcome the above-mentioned drawbacks and obtain a multicolor image with high clarity.

[0007]

SUMMARY OF THE INVENTION One aspect of the present invention provides
This is a multicolor electrocoagulation printing method including the following steps. A) providing an electrolytically inert anode having a continuous passive surface that moves at a substantially constant speed along a predetermined path, wherein the passive surface comprises an anode active surface. And b) present on the anode active surface in an electrocoagulated printing ink consisting of a liquid colloidal dispersion comprising an electrolytically coagulable colloid, a dispersing medium, a soluble electrolyte and a colorant. Forming a number of dots of colored coagulated colloid representing the desired image by electrocoagulation of the colloid that can be coagulated electrolytically; c) moving at substantially the same speed as the anode to form the dots of electrocoagulated colloid. Contacting a non-extensible endless belt having a colloid holding surface for releasably holding the colloid holding surface on one side thereof with the anode active surface; Causing the transfer of dots of colored coagulated colloid onto the holding surface, thereby printing an image on said colloid holding surface; and d) being located at predetermined locations along said path and each of a different color. Defining a substantial number of printing stages using colorants, thereby creating several different colored images of the coagulated colloid, at each transfer position said colored images are superimposed to obtain a multicolor image, Repeating steps b) and c) several times to be transferred onto the colloid holding surface; e)
Contacting the substrate with a colloid-retaining surface of the belt to cause the transfer of the multicolor image from the colloid-retaining surface onto the substrate, thereby printing the multicolor image on the substrate. The printing method provided.

Another embodiment of the present invention is an apparatus for performing the above-described method. That is, the apparatus of the present invention comprises an electrolytically inert anode having a continuous passive surface defining an anode active surface, and means for moving the anode active surface at a substantially constant speed along a predetermined path. A non-extensible endless belt having on one side thereof a colloid holding surface for detachably holding the dots of electrocoagulated colloid colloid; a means for moving the belt at substantially the same speed as the anode; and And a plurality of printing units arranged at predetermined positions along the liquid colloidal dispersion, wherein each of the printing units contains a colloid which can be electrolytically solidified, a dispersion medium, a soluble electrolyte and a colorant. By electrocoagulation of said electrolytically coagulable colloid present in an electrocoagulable printing ink consisting of a colored coagulated colloid representing the desired image on said anodic active surface Means for forming a number of dots and causing the transfer of dots of colored coagulated colloid from the anodic active surface onto the colloid holding surface of the belt, printing an image on the colloid holding surface, thereby differentiating the coagulated colloid Making several colored images, which are superimposed at each said transfer station to obtain a multicolored image,
Means for contacting the belt with the anodic active surface at each transfer station so as to be transferred onto the colloid holding surface; and causing transfer of the multicolor image from the colloid holding surface onto the substrate. Means for contacting the substrate with the colloid-retaining surface of the belt to thereby print the multicolor image on the substrate.

The present inventor has unexpectedly discovered that by using a non-extensible endless belt having a colloid-retaining surface, such as a porous surface, onto which the colored coagulated colloid can be transferred, and Such a belt,
Colloid retention of belts of different colored images during their transfer by moving the belt colloid retention surface from one printing unit to another printing unit independently of the anode and sequentially contacting the colored colloidal colloids during their transfer It is possible that the accuracy of registration on a surface can be significantly improved, thereby providing a high definition multicolor image that can subsequently be transferred onto a paper web or other substrate. I found it. For example, a belt made of a plastic material having a porous silica film can be used.

The anode used can be in the form of a moving endless belt as described in our US Pat. No. 4,661,222 or in our US Pat. No. 4,895,6.
No. 29 or the aforementioned US Pat. No. 5,538,601, in the form of a rotating cylinder, the teachings of which are incorporated herein by reference. In the latter case, the printing unit is arranged around a cylindrical anode. Preferably, to increase the viscosity of the coagulated colloid in step (b), the anode active surface and the ink are at about 35-60 ° C, preferably at 40 ° C.
, Which keeps the dots of the colored solidified colloids in close contact during their transfer in step (c) and enhances the transfer of the colored solidified colloid onto the substrate. For example, the anode active surface can be heated to a desired temperature, and the ink applied on the heated electrode surface is
From there, heat transfer to the ink occurs.

When using a cylindrical anode rotating at a substantially constant speed about the longitudinal central axis of the anode, the energization step of the electrocoagulation printing process described above can be suitably carried out as follows: i. ) Electrically isolated from each other and arranged in a linear array to define a series of corresponding cathode active surfaces, arranged in a plane parallel to the longitudinal axis of the anode and a certain predetermined gap from the anode active surface; Providing a plurality of electrolytically inactive cathodes spaced apart and each spaced apart by a distance at least equal to the electrode gap; ii) applying an oily material to the anode active surface Iii) filling the electrode gap with the electrocoagulated printing ink; iv) applying a voltage to a selected one of the plurality of cathodes while rotating the anode. Applying, selectively, one by one, the solidification and deposition of the ink on the anodic active surface coated with an oily substance, which is located opposite the electrode active surface of the applied cathode, thereby forming the colored solidified ink. Forming dots; and v) removing any remaining non-coagulated ink from the anode active surface.

As described in US Pat. No. 4,895,629, the placement of cathodes at a distance equal to or greater than the electrode gap prevents cathode edge corrosion. be able to. On the other hand, by coating the anode with an oily substance before applying a voltage to the cathode, the adhesion of the coagulated ink dots to the anode can be reduced, and uncontrollable corrosion of the anode can be prevented. When an olefinic substance is used as the oily substance, the gas generated as a result of electrolysis when a voltage is applied to the cathode is consumed by the reaction with the olefinic substance. Does not accumulate.

Suitable electrolytically inert metals that can constitute the anode and cathode include stainless steel, platinum, chromium, nickel and aluminum.
Preferably, the anode is formed from stainless steel, aluminum or tin, and upon application of a voltage to the cathode, dissolution of the oxide film forming the passivation on such an electrode results in metal ions, especially polyvalent metals. Ions are formed, which then initiate the solidification of the ink. Trivalent ions such as iron ions and aluminum ions are particularly preferred for initiating ink solidification.

The gap defined between the anode and the cathode ranges from about 50 μm to about 100 μm, with smaller electrode gaps resulting in sharper solidified ink dots. If the electrode gap is on the order of 50 μm, the cathodes are preferably spaced from one another at a distance of about 75 μm.

As the oily substance used for coating the surface of the anode in step ii), an olefinic substance is preferred. Suitable examples of this olefinic material include unsaturated fatty acids such as arachidonic acid, linoleic acid, linolenic acid, oleic acid and palmitoleic acid, corn oil,
And unsaturated vegetable oils such as linseed oil, olive oil, peanut oil, soybean oil and sunflower oil. further,
It is particularly preferred that the olefinic substance constituting the oily substance contains oleic acid in a ratio of 50% or more. The olefinic material can be applied to the anode active surface in the form of an oily dispersion containing the metal oxide as a dispersed phase. Examples of suitable metal oxides include aluminum oxide, ceric oxide, chromium oxide, cupric oxide, iron oxide, magnesium oxide, manganese dioxide, titanium dioxide and zinc oxide. Here, chromium oxide is a preferred metal oxide. The amount of metal oxide is
Depending on the type of metal oxide used, it is set in a range from about 1% by weight to about 50% by weight based on the total weight of the dispersion. When using an oil dispersion, about 75% by weight of oleic acid or linoleic acid and about 25% by weight of chromium oxide
It is particularly preferred to contain About 35-60 ° C
By operating at a temperature of, the concentration of metal oxides in the oily dispersion can be reduced, thereby reducing the wear of the anode active surface.

The oily substance containing an olefinic substance is
Advantageously, it is applied to the anode active surface as follows:
Providing a dispensing roller having a peripheral coating of an oxide ceramic material extending parallel to the cylindrical anode; applying an oily substance onto the ceramic coating to evenly coat the surface of the ceramic coating A coating of oily material is formed on the surface, wherein the coating of oily material is separated into microdroplets having a substantially uniform size and distribution; and the microdroplets are transferred from the ceramic coating to the anode active surface. And transition. If the oleaginous substance completely covers the entire anode surface, the anode is insulated and it is virtually impossible to conduct electricity.
Therefore, the oily substance is preferably applied in the form of microdroplets. As described in the inventor's U.S. Pat. No. 5,449,392 of Sep. 12, 1995,
By using a dispensing roller having a ceramic coating of an oxide ceramic material, a film of an oily substance that uniformly covers the surface of the ceramic coating can be formed on the surface of such a coating, and then the oily substance Is separated into microdroplets having a substantially uniform size and distribution. The microdroplets formed on the surface of the ceramic coating and transferred onto the anode active surface generally have a size in the range of about 1 to about 5 μm.

A particularly preferred oxide ceramic material for forming the above ceramic coating comprises a molten mixture of alumina and titania. Such a mixture comprises about 60 to about 90% by weight alumina and about 10 to about 40% by weight.
Of titania.

According to a preferred embodiment of the present invention, an applicator roller extending parallel to the distribution roller and forming a first nip in conjunction with the distribution roller is disposed, and the applicator roller and the distribution roller are arranged. The oily substance is supplied to the first nip while rotating while being aligned, so that the oily substance forms a film that uniformly covers the surface of the ceramic coating when passing through the first nip. Apply. Preferably, a transfer roller extending in parallel with the distribution roller and forming a second nip in pressure contact with the dispensing roller is disposed, and a transfer roller forming a third nip in pressure contact with the anode is positioned. And the anode are aligned and rotated to transfer the microdroplets from the distribution roller to the transfer roller in the second nip, and then transfer the microdroplets from the transfer roller to the anode in the third nip.
The microdroplets are transferred from the distribution roller to the anode. The arrangement of such rollers is described in US Pat. No. 5,449,392.
It is described in the issue.

The applicator roller and the transfer roller are
Each preferably has a surrounding coating of an elastic material, such as a synthetic rubber material, which is resistant to oily substances. For example, the applicator roller has a Shore A hardness of about 50 to about 70, and the transfer roller has a Shore A hardness of about 6.
Each of 0 to about 80 polyurethanes can be used.

The anodic active surface coated with an oleaginous material is preferably polished prior to step iii) in order to increase the deposition of microdroplets on the anodic active surface.
For example, a rotating brush comprising a plurality of radially extending bristles made of horse hair and having tips in contact with the surface of the anode can be used. It has been found that the friction created by the bristles contacting the surface upon rotation of the brush increases the deposition of microdroplets on the anode active surface.

Step iii) of the electrocoagulation printing process is advantageously carried out as follows. That is, the ink is continuously supplied onto the anode active surface from liquid supply means arranged adjacent to the electrode gap at a predetermined height with respect to the anode,
Allow the ink to flow along the anode active surface, and as the anode rotates, the ink is carried to the electrode gap,
It is to fill the electrode gap. Preferably, the excess ink flowing over the anode active surface is collected and the collected ink is recycled to the liquid supply.

The commonly used ink is a linear high molecular weight compound, that is, a component which can be electrolytically solidified.
About 10,000 to about 1,000,000, preferably 10
It preferably contains a polymer having a weight average molecular weight of from 000 to 600,000. Further, it is advantageous that the component capable of being electrolytically solidified contains a reaction site having a functional group selected from the group consisting of an amino group, an amide group and a carboxyl group, and the reaction site comprises an anode To form a chemical bond with a polyvalent metal ion, especially a trivalent ion such as an iron ion or an aluminum ion.
Specific examples of polymers suitable for printing inks include natural polymers such as albumin, gelatin, casein and agar, and synthetic polymers such as polyacrylic acid and polyacrylamide. A particularly preferred polymer is an acrylamide-acrylic acid anionic copolymer having a weight average molecular weight of about 250,000, and is available from Cyanamid Inc. under Acost Length 86 (AC
It is sold under the trademark COSTRENGTH 86). The polymer can be used in a liquid state, and may be a solution or a dispersion containing a colloid or the like. The polymer is preferably used in an amount of about 6.5 to about 12% by weight, more preferably about 7% by weight, based on the total weight of the ink. To provide the desired ink, water is preferably used as the medium for dispersing or dissolving the polymer.

[0023] The ink further contains a soluble electrolyte and a colorant. Preferred electrolytes are alkali metal halides and alkaline earth metal halides,
Examples include lithium chloride, sodium chloride, potassium chloride and calcium chloride. Of these, potassium chloride is particularly preferred. When operating at about 35-60 ° C, the electrolyte comprises about 4.5 to about 6 based on the total weight of the ink.
It is preferably used in an amount of% by weight. Dyes or pigments can be used as the colorant. Suitable dyes that can be used in the coloring ink include water-soluble dyes, such as Duassin Acid Black (Duesyn Acid Black) which is commercially available from Hoechst (HOECHST).
Black) or Duassin Acid Blue to color cyan
(Duasyn AcidBlue) or Riedel-Deen (RIED
EL-DEHAEN). Pina (Anti-Halo Dye Blue T. P
ina), Anti-Halo Dye AC Magenta Ex
tra V01 Pina) and anti-halodioxonol yellow N.I. Pina (Anti-Halo Dye Oxo
Nol Yellow N. Pina). When a pigment is used as a coloring agent, for example, carbon black Monarch (registered trademark) 12 for coloring black is used.
Pigment commercially available from CABOT CORP., Such as Carbon Black Monarch® 120, or
Hosta Palm Blue B2G or B3 to color cyan
G (Hostaperm Blue B2G or B3G), permanent rubin F6B or L6B (Permanent Rub) for coloring magenta
ine F6B or L6B) and permanent yellow DGR or DHG (Permanent Yellow DGR)
or DHG) can be used. In order to uniformly disperse the pigment in the ink, a dispersant is added. Suitable dispersants include the nonionic dispersants sold by ICI Canada Inc. under the trademark SOLSPERSE 27000. Preferably, the pigment is used in an amount of about 6.5 to about 12% by weight and the dispersant is used in an amount of about 0.4 to about 6% by weight, based on the total weight of the ink.

After coagulation of the ink, any remaining non-coagulated ink is removed from the anode active surface, for example by rubbing the surface with a soft rubber squeegee, to separate the coagulated ink from the non-coagulated ink and to form a colored coagulated ink. Expose completely. Preferably, the non-coagulated ink thus removed is collected, mixed with the collected ink, and the non-coagulated ink mixed with the collected ink is recirculated to the liquid supply means.

The reflection density of the colored coagulated ink dots can be changed by changing the voltage and / or pulse width of the pulse modulation signal applied to the cathode.

According to a preferred embodiment, the substrate is in the form of a continuous web and passes through the respective transfer positions necessary for printing the colored image in the printing process. Preferably, at each transfer position, there is provided a pressure roller extending parallel to the cylindrical anode and forming a nip in conjunction with the pressure contact so that the pressure roller is driven by the anode as the anode rotates. Then, the transfer step is performed by guiding the web to pass through the nip.

Preferably, there are at least two printing stages, each including one pressing roller, the pressing rollers being arranged in pairs, each pair of pressing rollers being diametrically opposed to one another.

Preferably, the pressure roller comprises a perimeter coating of a synthetic rubber material such as polyurethane having a Shore A hardness of about 95. It has been found that a polyurethane coating having such hardness further improves the transferability of the colored coagulation ink from the anode active surface to the substrate. The pressure applied between the anode and the pressure roller preferably ranges from about 50 kg / cm ² to about 100 kg / cm ² .

After the transfer step, the anodic active surface is usually washed to remove any remaining coagulated ink and oily substances from the anodic active surface. According to a preferred embodiment, the anode is rotatable in a predetermined direction to remove residual coagulated ink from its active surface as follows. That is, providing an elongated rotating brush extending parallel to the longitudinal axis of the anode, the brush comprising a plurality of radially extending bristles made of horsehair and having tips in contact with the anode active surface, wherein the bristles are The brush is rotated in a direction opposite to the direction of rotation of the anode to frictionally engage the anode active surface, and a jet of pressurized cleaning solution is sprayed against the anode active surface from either side of the brush. In such embodiments, heating the cleaning solution heats the anode active surface when it comes in contact with the cleaning solution, and transfers the heat from the anode active surface to the ink by supplying the ink on the heated anode surface. As it happens, it is preferred to maintain the anode active surface and the ink at a temperature of about 35-60 ° C.

Preferably, the electrocoagulated printing ink contains water as a dispersing medium, and the dots of the different colored coagulated colloid representation of the multicolor image are wetted between step (d) and step (e); The multicolor image is thus substantially completely transferred onto the substrate in step (e).

According to another preferred embodiment, the substrate is in the form of a continuous web, step (e) comprising forming a support roller and a nip extending parallel to the support roller and through which the belt passes. And a pressure roller pressed against the support roller, the support roller and the pressure roller being driven by a moving belt, and moving the web between the pressure roller and the colloid holding surface of the belt. Through the nip to print a multicolor image on the web. Preferably, the belt with its colloid-retaining surface, on which the multicolor image is printed, is guided to move along a path extending in a plane perpendicular to the longitudinal axis of the anode, whereby the web The colloid-retaining surface is exposed to allow its contact by

Preferably, the longitudinal axis of the anode extends vertically, and the belt is guided so as to move along a horizontal path with the colloid holding surface facing downward, and the support roller and the pressure roller are horizontal. It is arranged in a plane extending perpendicular to the path.

After step (e), the colloid-retaining surface of the belt is generally cleaned to remove any remaining coagulated colloid therefrom. According to a preferred embodiment, any remaining coagulated colloid is provided with at least one elongated rotatable brush located on one side of the belt, and on the other side of the belt extending parallel to the brush. The at least one supporting roller is used to remove the colloidal residual surface of the belt. The brush and the support roller have a rotation axis arranged in a plane extending orthogonally to the belt, and the brush has a number of radial directions made from horse hair and having tips in contact with the colloid holding surface. Bristles are provided. The brush is rotated in the direction opposite to the direction of movement of the belt to frictionally engage the bristles with the colloid holding surface while supporting the belt with the support roller, and pressure is applied to the colloid holding surface from either side of the brush A jet of the cleaned rinsing liquid is directed to remove the rinsing liquid along with any coagulated colloid removed from the colloid holding surface.

The present invention can significantly improve the accuracy of the registration of differently colored images of coagulated colloids on the colloid holding surface of the belt during their transfer, whereby the paper web or It is possible to provide a multi-color image with high clarity transferred on another substrate.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the multicolor electrocoagulation printing apparatus according to the present embodiment includes a central cylinder-shaped electrode (anode) 20 having the form of a rotating cylinder, and a cylinder-shaped electrode 20.
Four identical printing units 22 (2
2A, 22B, 22C, 22D). Among the printing units 22, the first printing unit 22A located on the left side in the figure is used for yellow printing, and the second printing unit 22B is used for yellow printing.
Is provided for magenta color printing, the third printing unit 22C is provided for cyan-green printing, and the fourth printing unit 22D is provided for black printing. The cylindrical electrode 20 extends in the vertical direction,
It has a shaft 24 driven by a motor (not shown) for rotating the electrodes about a vertical axis coinciding with the shaft 24. A non-extensible endless belt 26 having on one side thereof a colloid-retaining surface 28 (best shown in FIG. 4) as a porous surface, allows each printing unit 2 to print a different colored image on the colloid-retaining surface 28.
2A, 22B, 22C, 22D, and different colored images are printed on each of the printing units 22A, 22B, 22C, 2D.
At the 2D transfer station, they are transferred onto surface 28 in superimposition to give a multicolor image. The belt 26 has a longitudinally spaced two adjacent to its edge.
Driven at the same speed as the electrodes 20 by three pairs of sprockets 30 (only three sprockets are shown) having teeth 32 that mesh with a series of through holes 34, each pair of sprockets 30 is keyed to a respective shaft 36. The shaft 36 is mechanically connected to the shaft 24 of the electrode 20. The belt 26 is held in mesh with the sprocket 30 by the arc-shaped guide member 38.
The printing device further includes a wetting device (wetting means) 40 for wetting the dry dots of all the colored coagulated colloids on the surface 28 of the belt 26 and the display of the multicolor image.
The multicolor image is fed from the surface 28 of the belt 26 to the supply roller 4.
Transfer device (second contact means) 42 for transferring onto a paper web (substrate) 44 supplied from
And a cleaning device (third removing means) 48 for cleaning the surface 28 of the cleaning device 6.

As best shown in FIG. 2, each of the printing units 22 includes a cleaning device (second removing means) 50 for cleaning the surface 52 of the anode 20 and a olefinic substance and a metal oxide. An anode coating device (coating means) 54 for coating the surface 52; a polishing brush 56 for polishing the olefin and metal oxide-coated surface 52; and an ink supply device for pouring electrocoagulated printing ink onto the surface 52 ( A printing head 60 provided with a cathode 62 for electrocoagulating the colloid contained in the ink to form a colored coagulated colloid display dot of a desired image on the anode surface 52; A soft rubber squeegee (first removing means) 64 for removing any remaining non-coagulated colloid from the surface 52. Anode coating device 54, ink supply device 58, cathode 62, and rubber squeegee 6
Reference numeral 4 denotes a dot forming unit. Each printing unit 22 further contacts the belt 26 with the anode surface 52 to cause the dots of colored, coagulated colloid to
6 includes a pressure roller 66 (first contact means) for transferring onto the colloid holding surface 28 and thereby printing the image on the web. As shown in FIG. 1, by providing two pairs of diametrically opposed pressure rollers 66 disposed around the cylindrical electrode 20, the forces exerted by each pair of pressure rollers 66 are offset. Therefore, bending of the electrode 20 is prevented.

The anode cleaning device 50 includes a rotating brush 68 and two high-pressure water injectors 70 disposed in a housing 72, respectively. Each brush 68
Rotating counterclockwise, each brush 68 is provided with a number of radially extending bristles 74 made of horsehair and having tips that contact the surface 52. After the dots of the colored coagulation colloid have been transferred at the transfer station of the preceding printing unit, any coagulation colloid remaining on the surface 52 is removed by the brush 68 and the injector 70
Washed off by powerful jets of water created by.

The anode coating device 54 includes a distribution roller 76 extending vertically and a distribution roller 7 extending parallel to the distribution roller 76 and forming a nip 80.
Applicator roller 78 which meshes with pressure contact 6
And a nip 84 extending parallel to the roller 76.
And a transfer roller 82 meshed in contact with the roller 76 so as to form The transfer roller 82 is in pressure contact with the anode 20 so as to form a nip 86 and be driven by the rotating anode 20. Each coating device 54 further includes a supply device 88 for supplying the olefinic substance to the applicator roller 78 in the form of an oily dispersion containing a metal oxide as a dispersed phase.

The distribution roller 76 has a solid metal core 90 provided with a peripheral coating 92 of an oxide ceramic material. A pair of short shafts 94 (1
Only extend outward from the tip of the roller 76. Also, the applicator roller 78 and the transfer roller 82 have a solid metal core 96, which is provided with a polyurethane peripheral coating 98. Roller 7
6 and 78 are positioned and rotated by means of a motor (not shown) that drives a shaft 94 of the distribution roller 76. Driving from the motor causes the distribution roller 76 to rotate counterclockwise and then transmits clockwise rotation to the applicator roller 78.

The supply device 88 is provided so as to discharge the oily dispersion onto the applicator roller 78 at the upper part. The dispersion then flows down along the roller 78 by gravity and is conveyed by the roller 78 to the nip 80 during its rotation. This dispersion forms a film that uniformly covers the surface of the ceramic coating 90 of the distribution roller 76 as it passes through the nip 80, the film containing an olefinic material in a mixture with a metal oxide and substantially Resulting in microdroplets having a uniform size and distribution. The microdroplets formed on the roller 76 are conveyed to the nip 84 by the roller 76, where they are transferred onto the transfer roller 82. The microdroplets are then conveyed by rollers 82 to nip 86 where they are transferred onto anode 20.

A polishing brush 56 used to polish the olefin and metal oxide coated surface 52 of the anode 20
Are similar to brushes 68, each brush 56 rotating in a counterclockwise direction and each brush 56 has a number of radially extending bristles 74 made of horsehair and having tips in contact with surface 52. Is provided. When the brush 56 rotates,
The friction created by the bristles 74 in contact with the surface 52 has been found to increase the deposition of microdroplets of olefinic material containing metal oxides on the anode surface 52.

As shown in FIG. 3, each print head 60
Comprises a cylindrical body 100 having a cathode 62, the cathodes 62 being electrically insulated from one another and
Aligned along the length of 00 to define a series of corresponding cathode active surfaces 102. Print head 60
The surface 102 of the cathode 62 is arranged in a plane parallel to the central longitudinal axis of the electrode 20, and the surface 102 is constant and defined by a predetermined electrode gap 104.
It is arranged with respect to the anode 20 so as to be spaced from two. Also, the electrodes 62 are spaced from each other by a distance at least equal to the electrode gap 104 to prevent edge corrosion of the cathode.

The ink supply device 58 used to fill the electrode gap 104 with an electrocoagulated printing ink comprising a colloidal dispersion containing a colloid that can be electrolytically coagulated, a dispersing medium, a soluble electrolyte and a colorant is provided. , Disposed adjacent to the electrode gap 104 and disposed to discharge ink from a predetermined height with respect to the anode 20 onto the anode surface 52. As the ink is ejected from the device 58 onto the anode surface 52, the ink flows down along the surface 52 and is carried by the rotating anode 20 to the electrode gap 104 to be filled.

The application of a voltage to the selected cathode 62 occurs during rotation of the electrode 20 on the olefin and metal oxide coated surface 52 of the anode 20 opposite the electrode active surface 102 of the applied cathode 62. Causes the point-by-point selective coagulation and adhesion of the colloid to the colloid, thereby forming a series of corresponding dots representing the colored coagulation colloid of the desired image. After the colloid has been electrocoagulated, any remaining non-coagulated colloid is removed from the anode surface 52 by the squeegee 64 to completely expose the dots of colored coagulated colloid deposited on the surface 52.

The optical density of the colored solidified colloidal dots is:
The voltage of the pulse modulated signal applied to cathode 62 and / or
Alternatively, it can be changed by changing the pulse width. Synchronization of the data provided to print head 60
Secured by appropriate electronic circuitry (not shown).

At each transfer station, a belt 26
Pressure rollers 66, which serve to contact the anode with the anode active surface 52, respectively, form a nip 106 through which the belt 26 passes and allow the rollers 66 to be driven by the rotating anode 20. , Anode 20
Pressed against. With the surface 28 of the belt 26 in contact with the dots of the colored solidified colloid on the surface 52, the colored solidified colloid is transferred from the surface 52 onto the surface 28, thereby printing an image. The different colored images produced by the printing units 22A, 22B, 22C and 22D are then superimposed to obtain a multicolor image 108 (shown in FIG.
8 is transferred.

Next, the multicolor image 108 is conveyed by the belt 26 to the wetting device 40 which is arranged in the housing 112 and has a number of spray nozzles 110. Image 1
In order to wet all the dried dots of the colored coagulated colloid representing 08 and to ensure that the transfer device 42 transfers the multicolor image 108 from the surface 28 onto the paper web 44 substantially completely, An aqueous solution containing the activator is sprayed by nozzle 110 onto surface 28 of belt 26.

As shown in FIG. 4, the transfer device 42
It comprises a pair of angled fold bars 114, 114 'and guide rollers 116, 116' arranged in a mating relationship to guide the belt 26 so that the belt 26 faces the surface 28 downward. Surface 2 so that it can move along a horizontal path and make contact with the paper web 44.
8 is exposed. The apparatus further includes a support roller 118.
And the pressure roller 12 extending in parallel with the roller 118.
0, the pressure roller 120 forms a nip 122 through which the belt 26 passes, and
The rollers 118 and 120 are pressed against the support roller 118 so as to allow the rollers 118 and 120 to be driven.
The rotation axes of the support roller 118 and the pressure roller 120 are arranged in a plane that extends orthogonally to the horizontal path, and the belt 26 moves along the horizontal path. Paper web 44
Is a multicolor image 1 guided by a pair of guide rollers 124, 124 'and transferred from surface 28 onto web 44.
08 is printed so that the pressure roller 120 and the belt 2
6 through the nip 122 between it and the surface 28. Next, the paper web 44 on which the image 108 is printed is taken up by the collecting roller 126.

The multicolor image 108 is applied to the surface 28 of the belt 26.
To remove any residual coagulated colloid from surface 28 after transfer from paper 28 onto paper web 44.
6 is sent to the cleaning device 48. The cleaning device 48 includes two rotating brushes 128 arranged on one surface side of the belt 26,
It includes three high-pressure water injectors 130 (shown in FIG. 1), a rubber squeegee 132, and three support rollers 134 arranged on the other side of the belt, all of which are arranged in the housing 136. Each brush 128 rotates clockwise, and each brush 128 is made of horse hair and has a belt 2
A number of radially extending bristles 74 are provided having tips that contact the surface 28 of the sixth. Any coagulated colloid remaining on surface 28 is removed by brush 128 and washed away by the powerful jet of water created by injector 130.

[0051]

As described above, according to the present invention,
The electrocoagulated colloid dots of the multicolor image are transferred from the anode active surface to the colloid holding surface of the non-extensible endless belt, and the dots are transferred from the colloid holding surface to the substrate. The alignment accuracy of different colored images of the coagulated colloid is significantly improved, and as a result, the clarity of the multicolor image transferred onto the substrate is improved.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a multicolor electrocoagulation printing apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view partially showing one of the printing units.

FIG. 3 is a partial view of one of the print heads used for electrocoagulation of a colloid.

FIG. 4 is a partial perspective view of the apparatus of FIG. 1 schematically showing an image wetting apparatus, an image transfer apparatus, and a belt cleaning apparatus.

[Explanation of symbols]

Reference Signs List 20 cylinder electrode (anode) 22 printing unit 22A first printing unit 22B second printing unit 22C third printing unit 22D fourth printing unit 26 non-extensible endless belt 28 colloid holding surface 40 wetting device (wetting means) 42 transfer device (Second contact means) 44 Paper web (substrate) 48 Cleaning device (third removing device) 50 Cleaning device (second removing device) 52 Surface (continuous passivated surface) 54 Anode coating device (Coating device, dots) Forming means) 58 Ink supply device (filling means, dot forming means) 62 Cathode (dot forming means) 64 Soft rubber squeegee (first removing means, dot forming means) 66 Pressure roller (first contacting means) 102 Cathode activation Surface 104 Electrode gap 106 Nip 118 Support roller 120 Pressure roller 124 Guide row La (web guiding means) 124 'Guide roller (web guiding means) 122 Nip

Claims (11)

[Claims] 1. A multicolor electrocoagulation printing method comprising the steps of: a) keeping an anode active surface defined by a continuous passive surface of an electrolytically inert anode substantially constant along a predetermined path; B) electrocoagulating said colloid present in an electrocoagulated printing ink consisting of a liquid colloidal dispersion comprising an electrolytically coagulable colloid, a dispersing medium, a soluble electrolyte and a colorant. Forming a number of dots of colored coagulated colloid representing the desired image on the anode active surface; and c) placing a colloid holding surface releasably holding the electrocoagulated colloid dots on one side thereof. Contacting the anodic active surface with an inextensible endless belt that moves at substantially the same speed as the anodic active surface, from the anodic active surface to the colloid holding surface Transferring a dot of colored coagulated colloid onto the colloid holding surface and printing an image on the colloid holding surface; and d) repeating a plurality of colored images of coagulated colloid by repeating the steps b) and c) a plurality of times. Forming a multicolor image on the colloid holding surface by sequentially superimposing and transferring on the colloid holding surface; and e) contacting the substrate with the colloid holding surface of the belt, Transferring the multicolor image onto the substrate and printing the multicolor image on the substrate. 2. The method according to claim 1, wherein the substrate has a form of a continuous web, and the step (e) includes a supporting roller and a pressure roller extending parallel to the supporting roller. The pressure roller is pressed against the support roller so as to form a nip through which the belt passes, and the support roller and the pressure roller are driven by the moving belt and the web Guiding the web through the nip so that the multicolor image is printed on the web. 3. A multicolor electrocoagulation printing apparatus, comprising: an electrolytically inactive anode having a continuous passive surface defining an anode active surface movable at a substantially constant speed along a predetermined path. A non-stretchable endless belt having a colloid holding surface on one side thereof for detachably holding the electrocoagulated colloid dots, the non-extensible endless belt being movable at substantially the same speed as the anode active surface; A plurality of printing units, each having a dot forming means and a first contact means, arranged at a predetermined position, and a second contact means, wherein the dot forming means comprises a colloid which can be electrolytically coagulated and a dispersion The colloid present in an electrocoagulated printing ink comprising a liquid colloidal dispersion containing a medium, a soluble electrolyte and a colorant is electrocoagulated to form a desired image on the anode active surface. Forming a plurality of dots of colored coagulated colloid; the first contacting means contacting the belt with the anode active surface and depositing the colored coagulated colloid dots from the anode active surface onto a colloid holding surface of the belt. Is transferred, whereby a multicolor image is formed by superimposing a plurality of colored images having different coagulated colloids on the colloid holding surface sequentially passing through the plurality of printing units, wherein the second contact means includes: Contacting the substrate with the colloid holding surface to transfer the multicolor image from the colloid holding surface onto the substrate, whereby the multicolor image is printed on the substrate. Electrocoagulation printing equipment. 4. The apparatus according to claim 3, wherein the anode is a cylindrical electrode having a longitudinal axis at the center, and wherein the anode active surface moving means moves the cylindrical anode to the longitudinal axis. A multi-color electrocoagulation printing apparatus, characterized in that the printing unit is arranged around the cylindrical anode. 5. The apparatus according to claim 3, wherein said dot forming means comprises a plurality of cathodes, which are electrolytically inactive and selectively applied with a voltage, and an anode active surface comprising an olefinic substance. And coating means for coating with metal oxide, filling means for filling the electrode gap with the electrocoagulated printing ink,
First removing means for removing residual non-coagulated colloid from the anode active surface, wherein the cathodes are electrically insulated from each other and are disposed in a plane parallel to a longitudinal axis of the anode; Linearly arranged to define a cathode active surface separated from the anode active surface by a constant and predetermined electrode gap; and
Spaced apart from each other by a distance at least equal to the electrode gap, the coating means forming microdroplets of an olefinic material containing a metal oxide on the anodic active surface; When a voltage is applied, the point-by-point selective coagulation and deposition of the colloid on the anode active surface coated with olefin and metal oxide opposite the electrode active surface of the applied cathode occurs. A multicolor electrocoagulation printing apparatus, wherein dots of the colored coagulation colloid are formed. 6. The apparatus according to claim 3, wherein the first contact means for contacting the belt with the anode active surface extends parallel to the anode. A pressure roller, wherein the pressure roller forms a nip through which the belt passes, and is pressed against the support roller so that the pressure roller is driven by the rotating anode. Multicolor electrocoagulation printing device. 7. The apparatus according to claim 3,4,5, or 6, wherein each of the printing units comprises: after the dots of the colored solidified colloid have been transferred onto the colloid holding surface; A multicolor electrocoagulation printing apparatus, further comprising second removing means for removing remaining coagulated colloid from the anode active surface. 8. The apparatus of claim 3, 4, 5, 6, or 7, wherein the dispersion medium is water, and wherein the apparatus has different colors representing the multicolor image. After the dots of the coagulated colloid have been transferred onto the colloid holding surface, the method further comprises wetting means for wetting the dots so that the multicolor image is substantially completely transferred onto the substrate. Multicolor electrocoagulation printing equipment. 9. The apparatus according to claim 3, wherein the substrate has a form of a continuous web, and the web has a colloidal retention of the belt. The second contact means for contacting the surface includes a support roller, a pressure roller extending in parallel with the support roller, and a web guide means, wherein the pressure roller has a nip through which the belt passes. While being formed, the supporting roller and the pressing roller are driven by the moving belt so as to be pressed against the supporting roller, and the web is guided by the web guiding means to form the pressing roller and the colloid. A multicolor electrocoagulation printing device, characterized in that the multicolor image is printed on the web through the nip between the holding surface and the nip. 10. The apparatus according to any one of claims 3, 4, 5, 6, 7, 8, or 9, wherein the apparatus comprises: A multicolor electrocoagulation printing apparatus, further comprising third removing means for removing remaining coagulated colloid from the colloid holding surface. 11. The method of claim 3, 4, 5, 6, 7, 8, 9,
11. The multicolor electrocoagulation printing apparatus according to claim 10, wherein the colloid holding surface is a porous surface made of a porous silica film.