JPH03223376A - Ink for image recording - Google Patents

Abstract

PURPOSE:To obtain an ink for image recording which can give an image with improved sharpness and anti-fogging property by incorporating two or more specific substances into the ink which has such a property that it adheres to only one of a pair of electrodes being in contact therewith when a voltage is applied from these electrode. CONSTITUTION:At least fine particles (e.g. octahedral synthetic smectite), a liquid dispersion medium (e.g. glycerine or water) and a foaming agent (e.g. sodium bicarbonate) are incorporated in an ink which has such a property that it adheres to only one of a pair of electrodes being in contact therewith when a voltage is applied from these electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application J] The present invention relates to an ink used for image formation, the adhesion of which changes with the application of voltage.

[Conventional technology 1] Traditionally, recording peripherals for computers, etc.
Printers using various recording methods, such as laser beam printers, inkjet printers, thermal transfer printers, wire tod printers and daisy-foil printers.
The applicant has also previously proposed a recording method in which a patterned tackiness is chemically imparted to ink and the difference between tackiness and non-tackiness of this ink is utilized for recording. (Unexamined Japanese Patent Publication No. 63-30279).

However, none of the above-mentioned recording methods is suitable for mass printing in terms of cost, etc. Conventionally, methods suitable for mass printing include lithographic printing, letterpress printing, and gravure printing. In these conventional printing methods, it is common to first apply ink to the surfaces of several rolls provided in succession, and then apply it to a plate when the ink becomes sufficiently thin.

The present applicant also applied a voltage to the ink to change the adhesion of the ink to perform printing (Japanese Unexamined Patent Publication No. 12617/1983).
proposed.

[Problems to be Solved by the Invention] The present invention further improves the ink used in the printing method by changing the adhesion of the ink by applying a voltage. An object of the present invention is to provide an image recording ink that eliminates fogging in image areas and can obtain images of higher quality than conventional ones.

[Means for Solving the Problems] The present invention is characterized in that a voltage is applied from a pair of Yin and Yang electrodes in contact with the ink, so that the adhesive properties are reduced so that the ink adheres only to one electrode and does not adhere to the other electrode. The present invention is a variable ink for image recording, which is characterized by containing at least fine particles, a liquid dispersion medium, and a foaming agent.

According to the present invention, the step of supplying ink whose adhesion changes depending on the polarity of the applied voltage between a pair of electrodes, applying a voltage between the pair of electrodes, and applying the ink onto one of the electrodes. a step of adhering, and the adhering ink,
In an image forming method that includes a step of transferring to a recording medium, a foaming agent is included in the ink to generate gas at the interface between the electrode and the ink, making the ink non-adhesive, thereby removing the image on the plate. It is possible to reliably prevent ink from adhering to the area, eliminate fogging, and improve image quality.

Hereinafter, the principle of the image forming method according to the present invention will be explained with reference to the drawings. "%" and "parts" are based on weight unless otherwise specified.

FIG. 1 shows one embodiment of an apparatus for forming an image using the ink of the present invention. In the figure, an ink carrying roll 1 is a member that has a cylindrical shape and rotates in the direction of the arrow. The roll 1 is made of a conductive material such as aluminum, copper, or stainless steel. The surface of the ink carrying roll 1 (
On the cylindrical surface (cylindrical surface), ink 2, which is a recording material, is formed to have a uniform thickness by a coating roll 9 rotating in the direction of arrow E. The ink roll 11 has a cylindrical shape, rotates in the direction of arrow F in the opposite direction to the coating roll 9, and takes ink into and out of the ink fountain I2. The roll 11 is made of a conductive material such as aluminum, copper, or stainless steel. Further, electricity is supplied between the roll 9 and the roll 11 by the DC power supply 104. Further, the DC power supply 105 can apply a voltage between the ink carrying roll 1 and the coating roll 9.

The ink carrying roll 1 is connected to one end of a DC power supply 103. The ink 2 on the surface of the ink carrying roll 1 is in contact with the plate 4 wound around the plate roll 3.
is rotating in the direction of arrow B in the opposite direction to roll l. Edition 4
For example, as shown in FIG. 2, a desired pattern 4b made of an insulating material is provided on a base material 4a made of a conductive material such as metal.

As the material of the base material 4a, aluminum, copper, stainless steel, platinum, gold, chromium, nickel, steel copper, carbon, etc., or conductive polymers or various polymers in which metal fillers are dispersed are used. Materials for pattern 4b include thermal transfer recording materials (mainly wax and resin),
Electrophotographic toners Vinyl polymers and natural or synthetic polymers are used.

In this way, by applying a voltage between the plate 4 and the ink carrying roll 1 by the power supply 103, the adhesion of the ink 2 that comes into contact with the conductive portion of the plate 4 changes, and the difference in adhesion causes the ink 2 to be applied onto the plate. Pattern ↓ v I Tsuno 4 Power Naichi ν Kami Eino ~, A 14% Su, Wataru Yumi Toramon χ The voltage of power supply 103, 104, and 105 is practically 3
~100 ■, more preferably 5 ~ 80 ■ DC voltage,
The image quality can be made even sharper by further applying a high frequency (lOHz to 100 KHz) AC bias voltage.

The thickness of the layer of ink 2 formed on the surface of the ink carrying roll 1 is (the thickness of the ink carrying roll l and the coating roll 6
the size of the gap, the fluidity or viscosity of ink 2,
Although it varies depending on the material or roughness of the surface of the ink carrying roll 1 or the rotational speed of the roll 1, etc.), at the ink transfer position where this roll 1 faces the pattern plate 4 on the plate roll 3, the distance is approximately 0.001 to 100 mm. It is preferable that the degree of

If the thickness of this ink layer is less than 0.001 mm, it will be difficult to form a uniform ink layer on the ink carrying roll 1. On the other hand, if the ink layer thickness exceeds 100 mm, the surface layer of the ink layer (the layer on the side that contacts the conductive pattern plate roll 4) should be kept at a uniform circumferential speed.
It also becomes difficult to conduct electricity between the ink carrying roll 1 and the plate 4.

Next, the ink image on the plate 4 is transferred to the blank cylinder 5, which rotates in the direction of arrow C while being in pressure contact with the plate 4, and the ink image on the blank cylinder 5 is further rotated in the direction of the arrow while being in pressure contact with the blank cylinder 5. The ink image is transferred onto a recording medium 7 (paper, cloth, metal sheet, etc.) passing between impression cylinders 6, and an image 8 corresponding to the ink image is formed on the recording medium 7.

In some cases, the ink image on the plate 4 may be directly transferred onto the recording medium 7 without providing the blank cylinder 5, but if the blank cylinder 5 is provided, the material of the blank cylinder 5 may prevent wear and deterioration of the plate. In addition, an image (positive image) having the same pattern as the plate can be obtained on the recording medium.

In addition to the above, a plate having an insulating film on which an image-like conductive pattern is formed by discharge breakdown on a base material made of a conductive material can also be used. Furthermore, a plate having a photographic image in which a conductive pattern of a silver image is formed by depositing silver particles on a base material made of a conductive material can also be used.

In the example shown in Fig. 1, the plate 4 is used by being wound around a cylindrical plate roll 3, but the plate 4 is used as an electrode as it is, and ink is applied to the plate and the plate and counter electrode are connected. An ink image can be formed on the plate even if a voltage is applied with the ink sandwiched therebetween.

Image forming methods to which the ink of the present invention can be preferably applied include:
As explained above, the electrode (
This method takes advantage of the fact that the adhesion of the ink changes depending on the pattern of the electrodes by supplying a specific ink between the plate and the counter electrode and applying a voltage between the pair of electrodes.

The ink used preferably has adhesive properties when no voltage is applied, and when a voltage is applied,
The adhesive property disappears, and the ink adheres to the insulating portion of the plate, forming the desired recorded image.

The following reasons can be considered for the mechanism by which the ink changes from adhesive to non-adhesive due to voltage application.

In other words, the ink electrolyzes when it is energized by applying a voltage, generating gas and changing its adhesion.The ink is originally adjusted to have adhesion, and the application of voltage causes the ink to change near one electrode. generates gas,
This gas prevents ink from adhering to the electrodes. In order for the ink to electrolyze and generate gas, it is preferable to dissolve the electrolyte in the solvent in the ink.The lower the electrical resistance of the ink, the better the volume resistance is 10'Ω・
The zero volume resistance is preferably 10'Ω・cm or less.
If it exceeds cm, the amount of current will decrease, or a high voltage will be required to prevent the amount of current from decreasing.

The foaming agent further increases the amount of gas generated and promotes ink non-adhesion, thereby eliminating fog in non-image areas and making it possible to print with sharp image quality. The foaming agent may be one that generates gas at the interface between the ink and the electrode when energized or heated by energization.
Both inorganic and organic blowing agents can be used.

Examples of inorganic blowing agents include sodium hydrogen carbonate, ammonium carbonate, ammonium hydrogen carbonate, ammonium nitrite, sodium carbonate, potassium hydrogen carbonate, potassium carbonate, and the like. Examples of organic blowing agents include dinitrosopentamethylenetetramine (DPT), N,
Nitroso compounds such as N'-dimethyl-N,N'-dinitrosoterephthalamide (DMDNTA); benzenesulfonyl hydrazide (BSH), p-toluenesulfonyl hydrazide (TSH), diphenylsulfone s, s'
Disulfonyl hydrazide (DPSDSH), 4.4°-oxybisbenzenesulfonyl hydrazide (
Sulfonic acid hydrazide compounds such as OBSH); azo and diazo compounds such as azodicarbonamide (ADCA), azobisisobutyronitrile (AIBN), diazoaminobenzene (DBA), barium azodicarboxylate, trihydrazinotriazine, etc. can be mentioned.

The foaming agent is 0.05 to 1O per 100 parts by weight of ink.
It is added in an amount of about 0.1 to 5 parts by weight.

A foaming aid may be used in combination to promote gas generation by decomposition of the foaming agent. Examples of foaming aids include: zinc compounds: zinc white, zinc caprylate, zinc nitrate, zinc fatty acid soap; lead compounds: lead carbonate, lead phthalate, lead phosphite, lead stearate, urea, borax, ethanolamine, Examples include phthalic anhydride.

When the foaming agent is foamed by heating, heat is generated by simply sandwiching the ink between the electrodes and applying electricity, but means for heating the electrodes may be provided to further promote decomposition of the foaming agent. For example, it is preferable to provide a heating resistor on the surface of the electrode and cause the heating resistor to generate heat by applying electricity, or to raise the plate surface temperature by passing a heat pipe, heating wire, etc. through the printing roll.

In general, when ink is a liquid such as alcohol, the cohesive force is weak and suitable adhesiveness cannot be obtained. It is preferable that this ink is of such an extent that, for example, when the ink is applied to a platinum-plated stainless steel plate vertically upright to a thickness of 2 mm, the ink is substantially retained on the platinum-plated stainless steel plate. . In addition, ink was sandwiched between two platinum-plated stainless steel plates to make the ink thickness 2 mm, and when the two platinum-plated stainless steel plates were separated from each other with no voltage applied, ink did not appear on either plate. It is preferable that they adhere to the same degree.

An ink that uses the above mechanism is basically composed of inorganic or organic fine particles, a liquid dispersion medium, and a foaming agent, and a coloring agent and the like are added as appropriate.

In a preferred embodiment of the ink, considering the viscoelastic properties of the ink, it is preferable to use swellable fine particles capable of retaining a liquid dispersion medium as all or part of the fine particles in the ink. Examples of such swellable fine particles include Na-montmorillonite, Ca-montmorillonite, 3-octahedral synthetic smectite, Na-hectorite, Li-hectolite, Na-teniolite, Na-tetrasilicic mica, Li-teniolite, etc. These include fluorinated mica, synthetic mica, and silica. The above-mentioned fluorinated mica can be represented by the following general formula (1).

General formula (1) % formula %) In the formula, W is Na or Li, X and Y are Mg2+Fe
”, Ni”, Mn”, AI”, Fe”, Li
6-coordinate ions such as +, 2 is A W, Si4+, G
e44t Fe5a F33 (- or a combination of these (
It represents a cation with a coordination number of 4, such as AI"/Si").

The average particle diameter of the swellable fine particles is preferably 75 μm or less in a dry state, more preferably 08 to 15 μm, and preferably 8 μm or less.

The content is 4 to 60 parts by weight per 100 parts by weight of ink.
Parts by weight are preferably 8 to 47 parts by weight.

In addition, fine particles, whether swollen or non-swollen, can be used for the purpose of adjusting the non-adherence of the ink.The fine particles can be dispersed in the liquid dispersion medium mentioned above, for example, by crosstalk in a homogenizer, colloid mill, or ultrasonic disperser. A body is formed.

Fine particles include metal (Au, Ag, Cu, etc.) particles, sulfides (zinc sulfide ZnS, antimony sulfide 5B2S).
3. Potassium sulfide with 2S, calcium sulfide CaS, germanium sulfide GeS, cobalt sulfide CoS, tin sulfide S
nS, iron sulfide FeS, copper sulfide Cu, S, manganese sulfide M
nS, molybdenum sulfide Mo25s, etc.) particles, silicic acid (
Orthosilicic acid H45i04, metasilicic acid HzSiDs,
Mesotrisilicate H2S120s, mesotrisilicate H45i
zCb, mesotetrasilicate HsSi40+ 1, etc.) particles, polyamide resin particles, polyamideimide resin particles, iron hydroxide particles, aluminum hydroxide particles, fluorinated mica particles, polyethylene particles, montmorillonite particles, fluorine resins, etc. . Further, polymer particles containing various charge control agents used as toners for electrophotography can also be used.

The above-mentioned non-swellable fine particles have an average particle diameter of 100 μm.
m or less, preferably 0.1 μm to 20 μm, especially 10
100 parts by weight of the ink, preferably 3 parts to 90 parts by weight, more preferably 5 parts by weight or more, based on 100 parts by weight of the ink.
It can be contained in an amount of 60 parts by weight.

Liquid dispersion media that can be used in the ink of the present invention include water,
Ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol (weight average molecular weight: approximately 100-1000), ethylene glycol 1000 methyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, methyl calpitol, Ethylcarpitol, butylcarpitol,
Ethyl carpitol acetate, diethyl carpitol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, glycerin, triethanolamine, formamide, dimethyl formamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone,
1.3-dimethylimidazolidinone, N-methylacetamide, ethylene carbonate, acetamide, succinonitrile, dimethylsulfoxide, sulfolane, furfuryl alcohol, N,N-dimethylformamide, 2-ethoxyethanol, hexamethylphosphoric Triamide (hexamethylphosphoric acid triamide), 2-nitropropane, nitroethane, γ-butyrolactone, propylene carbonate, l,2,6-hexanetribyl, dipropylene glycol, hexylene glycol, etc., glycerin-ethylene oxide addition polymer Alkylene oxide derivatives of glycerin such as glycerin-propylene oxide addition polymers, propylene oxide and ethylene oxide addition polymers, and other solvents consisting of mutual derivatives of each of the above solvents, etc., alone or in combination of two or more are used. be able to.

The amount of this liquid dispersion medium is 35 to 100 parts by weight per 100 parts by weight of ink.
It is contained in an amount of 85 parts by weight, preferably 45 to 75 parts by weight.

If the change in ink adhesion is due to gas generation due to electrolysis, it is possible to generate gas at one pole (especially the cathode) and suppress or weaken the gas generation at the other pole (especially the anode). It is preferred to increase the change in adhesion of the solvent, and it is preferable to select the solvent in such a manner.Furthermore, the solvent includes potassium iodide, sodium iodide, potassium thiocyanate, potassium bromide, sodium bromide, tetraethylammonium oxalide, LiBF4. It is preferable to contain electrolytes such as alone or in a mixture of two or more types, but the electrolyte is not limited to the above, and electrolytes and ionic surfactants that dissolve in a solvent and have the effect of lowering electrical resistance. etc. can be widely used.

It is preferable that the electrolyte is contained in a saturated dissolution amount of 0.0001 mol/β to the liquid dispersion medium. 0.0001mol/
If it is less than 1, no effect of the electrolyte will be observed, and if it is more than the saturated dissolution amount, the ink will become non-uniform, which is not preferable.

If necessary, the ink can contain colorants such as carbon black and other dyes and pigments that are generally used in the fields of printing and recording. When the ink contains a colorant, the content of the colorant is 0 per 100 parts by weight of the ink.
．． 1 to 40 parts by weight, more preferably 1 to 20 parts by weight.

Further, instead of or together with the coloring material, a coloring compound that develops color upon application of voltage may be contained. In addition, the ink may contain an electrolyte, thickener, thinner, surfactant, etc. that impart conductivity.

Furthermore, it is also possible for the above-mentioned fine particles themselves to also function as a coloring material.

In a preferred embodiment, in order to control the viscosity of the ink, the above-mentioned polymer soluble in the liquid dispersion medium is added to the ink material in an amount of 1 to 90 parts by weight, more preferably 1 to 90 parts by weight, based on 100 parts by weight of the ink material.
It can be contained in an amount of 50 parts by weight, particularly 1 to 20 parts by weight. Such polymers include guar gum, locust bean gum, gum arabic, taragant,
Plant-based polymers such as carrageenan, pectin, mannan, and starch; Microbial polymers such as xanthan gum, dextrin, succinoglucan, and curdlan; gelatin,
Animal-based polymers such as casein, albumin, and collagen; cellulose-based polymers such as methylcellulose, ethylcellulose, and hydroxyethylcellulose; starch-based polymers such as soluble starch, carboxymethyl starch, and methyl starch; alginic acid-based polymers such as propylene glycol alginate, and alginates. , Semi-synthetic polymers such as their geosaccharide derivatives: vinyl polymers such as polyvinyl alcohol, poly(andylpyrrolidone), polyvinyl methyl ether, carboxyvinyl polymer, sodium polyacrylate; their derivatives polyethylene glycol, ethylene oxide, propylene oxide block copolymers, alkyd resins, phenolic resins, epoxy resins,
Synthetic polymers such as aminoalkyd resins, polyester resins, polyurethane resins, acrylic resins, polyamide resins, polyamideimide resins, polyesterimide resins, and silicone resins can be used alone or in combination of two or more. It is also possible to use greases such as silicone grease and liquid polymers such as bolybdenum.

The ink of the present invention is prepared by mixing the above-mentioned materials, roll milling,
It is obtained by kneading with a colloid mill or the like.

[Example] Hereinafter, the present invention will be explained according to examples.

Example 1 Ink formulation glycerin 70 parts water
30 parts lithium borofluoride
7 parts pigment 10 parts
(manufactured by Bayer AG, product name, 5upranol Cyanine 78F)
Sodium hydrogen carbonate 6 parts 3-octahedral synthetic smectite 48 parts (manufactured by Kunimine Kogyo Co., Ltd., trade name, Smecton SA) Surfactant
8 parts (hexaglycerin borolysylte) A blue amorphous solid ink was prepared by kneading the mixture of the above formulation in a roll mill.

After applying the above ink to a thickness of approximately 2 mm on a 1 cm x 1 cm platinum-plated stainless steel plate, the platinum-plated stainless steel plate of the same size was placed on top of the ink, and then the two sheets were coated under no voltage. When the two platinum-plated stainless steel plates were separated by gradually widening the interval between the platinum-plated stainless steel plates, ink was found to have adhered to almost the entire area on both platinum-plated stainless steel plates.

Next, a voltage of +30μ was applied to both platinum-plated stainless steel plates with a 2 mm thick ink layer sandwiched between them, with one side serving as the cathode (earth) and the other as the anode. When the two platinum-plated stainless steel plates were separated by gradually increasing the distance between them, all the ink adhered to the anode side electrode.
There was no ink adhesion on the cathode side.

Next, image formation was performed using the printing machine shown in FIG.

As the ink carrying roll, a platinum-plated stainless steel cylindrical roll (surface roughness IS) was used, and as the plate roll 3, a diameter 30 mm roll with a hard chrome-plated surface was used.
A cylindrical roll made of iron with a diameter of mm was used. Also, as version roll 3,
An iron cylindrical roll with a diameter of 30+nm and whose surface was plated with hard chrome was used.

A plate 4 patterned with vinyl resin on an aluminum plate is wound around this plate roll 3, and the ink carrying roll 1
The above-mentioned ink material was placed between the roller and the coating roll 9. The ink carrying roll 1 was rotated at a circumferential speed of 5 mm/sec in the six directions of the arrows, and the gap between the coating roll 9 and the coating roll 9, which was a cylindrical roll made of surface Teflon rubber and rotating in the direction of the arrow E, was controlled.
By rotating at mm/sec, the ink layer thickness on the ink carrying roll 1 was controlled to 0.2 mm. The plate roll 3 was rotated in the direction of arrow C at a circumferential speed of 5 mm/sec.

When printing was performed with no voltage applied from the DC power supply 103 of this printing machine, no image-like printed matter was obtained, but when printing was performed with a DC voltage of 30V applied from the DC power supply 103, A large number of prints with sharp image quality and no fogging were obtained (at this time, the plate roll 3 was used as a cathode and the ink carrying roll 1 was used as an anode).

Example 2 Ink formulation glycerin 50 parts water
50 parts carbon black
10 parts Swellable mica 60
parts (manufactured by Tobi Kogyo Co., Ltd., Lithium Taeniolite) Lithium borofluoride 10 parts Benzene sulfonyl hydrazide 6 parts According to the above recipe,
A black ink was prepared in the same manner as in Example 1. Silicone oil heated to 80°C was circulated inside the plate roll 3 of the apparatus shown in FIG. 1 to bring the temperature of the plate 4 to 75°C.

In this state, image formation was performed while applying a voltage in the same manner as in Example 1, and a large number of prints with sharp image quality without fogging were obtained. Image quality was obtained.

Example 3 Ink formulation glycerin 50 parts water
50 parts carbon black 10 parts dinitrosopentamethylenetetramine 5 parts phthalic anhydride
1 part 3-octahedral synthetic smectite 50 parts (manufactured by Kunimine Kogyo Co., Ltd., trade name,
Smecton SA) In the same manner as in Example 2, a black ink was prepared according to the above recipe and images were formed, and a large number of prints with sharp image quality and no fogging were obtained.

Comparative Example 1 Example 1 except that sodium hydrogen carbonate was not added
When ink was obtained in the same manner as above and an image was formed, fogging was observed in the printed matter and only images of low quality were obtained.

Comparative Example 2 An ink was obtained in the same manner as in Example 2 except that benzenesulfonyl hydrazide was not added, and when an image was formed, fogging was observed in the printed matter and only images of low quality were obtained.

〔Effect of the invention〕

By using the ink containing the foaming agent of the present invention,
It promotes the non-adhesion of ink and can print images with no fog and sharp image quality, and is an extremely well-implemented image forming method suitable for recording peripheral devices connected to various devices such as computers. Ink that you can do.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus for forming an image using the ink of the present invention, and FIG. 2 is a schematic diagram showing an example of a plate that can be used in the image forming apparatus using the ink of the present invention. FIG. 1: Ink carrying roll 2: Ink 3: Plate roll
4: Plate 4a: Base material 4b: Pattern 5 Nib run cylinder 7: Recorded object 9: Coating roll 11: Ink roll 103.104.105: Power supply 6: Impression cylinder 8: Ink image 10: Ink reservoir 12: Ink fountain

Claims (1)

[Claims] 1) An ink whose adhesion properties change so that it adheres only to one electrode and does not adhere to the other electrode when a voltage is applied from a pair of Yin and Yang electrodes that are in contact with the ink, and at least fine particles and liquid An image recording ink characterized by containing a dispersion medium and a foaming agent.