JPH0452178A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image formation device having durability by making at least one electrode include conductive carbon and/or specific rubber material such as graphite and nitrile rubber. CONSTITUTION:As a surface material of a roller 4 which also serves as an electrode, conductive rubber is to be used. The conductive rubber is made such a manner that conductive carbon and/or conductive graphite is included in at least one material out of nitrile rubber, butyl rubber, chloroprene rubber, ethylene propylene rubber, chlorosulphonated polyethylene, chlorinated polyethylene, and polyfluoride ethylene resin. A form plate 9 to be mounted on a plate cylinder 5 serves as an electrode pairing with the roller 4 and is constituted so as to form an insulating pattern 9b on a conductive base material 9a. Rollers 1-4 supply an ink 10 on the form plate 9. At the same time, when a voltage is applied from a power source 11 between the form plate 9 and the roller 4 having the ink 10, the ink sticks to only on the insulating pattern of the form plate 9, so that a large number of printed matters having sharp image quality can be obtained and no irregularity be seen in the rubber material on the surface of the roller 4.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to image formation in which a recording material is attached to a plate in a pattern corresponding to a desired image, and the pattern is transferred to a transfer medium to form an image. Regarding equipment.

[Prior Art 1] Conventionally, image forming 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 the plate when the ink becomes sufficiently thin.

In such an image forming method, in order to adjust the amount of ink transferred, a large number of inking rollers, from 6 to several tens of inking rollers, are required, which increases the size of the device and also requires the use of each roller. There was a problem in that maintenance for proper operation was complicated.

[Problems to be Solved by the Invention] In order to solve the above problems, the present applicant has developed an image forming system using a compact device that can adjust the amount of ink transfer without using a large number of rollers, is easy to maintain, and is compact. proposed a method that could be carried out (patent application 1986-1).
No. 2617).

This method is a method of printing by changing the adhesion of ink by applying a voltage. In the equipment used in this method, it is possible to use a rubber material in which carbon and binder are dispersed in various rubbers in order to uniformly coat the ink on the substrate or roll and apply voltage to the ink. .

However, in the above printing method, a pH change occurs at the interface between the rubber material and the ink due to electrolysis of the ink.For example, when conductive rubber is used as an anode, the surface of the conductive rubber becomes a strongly acidic atmosphere, and when conductive rubber is used as a cathode, A strong alkaline atmosphere will be created. Under strong acidity or strong alkalinity, rubber will dissolve and at the same time carbon will fall off. the result,
In areas where carbon has fallen off or rubber has melted, conductivity is lost, resistance increases, and the surface loses its smoothness and becomes uneven. When the resistance value of the rubber material increases locally, current no longer flows uniformly between the conductive rollers or between the conductive roller and the conductive substrate. Therefore, in areas where current does not flow significantly, it is not possible to apply a voltage to the ink to change its adhesion, and good printed matter cannot be obtained.

Furthermore, if the roll surface becomes uneven, it becomes difficult to coat the ink uniformly.

An object of the present invention is to solve such problems and provide an image forming apparatus that does not cause deterioration of the rubber material even when voltage is applied from the rubber material to the ink over a long period of time, and that produces good printed matter. be.

[Means for Solving the Problems 1] The present invention applies a voltage between a pair of electrodes, the electrodes in contact with the ink, so that the ink adheres only to one electrode and does not adhere to the other electrode. and a means for applying a voltage between the pair of electrodes, wherein at least one of the electrodes includes a) conductive carbon and/or conductive graphite, and b) nitrile rubber. The image forming apparatus is characterized in that it contains at least one of butyl rubber, chloroprene rubber, ethylene propylene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, and polyfluorinated ethylene resin.

According to the present invention, the above object has been achieved by including a rubber material that does not dissolve even in an acidic or alkaline atmosphere in at least one of the electrodes.

The structure of this electrode is such that the entire electrode is
It may consist only of the above components, but a part of the electrode, especially the surface that comes into contact with the ink, may consist of the above components!
As long as the conductivity, elasticity, and alkali resistance of the electrode are not impaired,
In addition to the above components, a known binder or the like may be mixed.

The ratio of components a and b is preferably 5 to 800 parts by weight, more preferably 1 part by weight, based on 1001iJi parts.
It is 0 to 600 parts by weight.

Further, the primary particle diameter of carbon is preferably 5 to 40 mμD, and may have a crystal structure such as a graphite structure.
In that case, the particle size may be about 30 μrn-1 mm.

The manufacturing method for these electrodes is to knead desired amounts of a and b, mold by straining, extrusion, transfer, injection, etc., and heat as necessary to create a network bond to form elastic conductive rubber. I can do it.

Hereinafter, the principle of the image forming method according to the present invention will be explained with reference to the drawings. "%" and "1 part" are based on weight unless otherwise specified.

FIG. 1 shows one embodiment of the apparatus of the present invention. Rollers 1 to 4 are means for supplying ink 8, and roller 4 is configured to form a pair of electrodes with plate 9.

The material of the surfaces of the rollers 1 to 3 is not particularly limited, and for example, metal materials such as stainless steel, rubber materials such as silicone rubber, plastic materials, etc. are used.

In the present invention, the surface material of the roller 4, which also serves as an electrode, is a conductive rubber made by containing the material a) in at least one of the materials shown in b).

The hardness of this conductive rubber is 50° to 95 according to JIS hardness A standard.
The angle is preferably 60° to 90°, more preferably 60° to 90°.

The plate cylinder 5 on which the plate 9 is mounted is made of a metal material such as stainless steel, and may be configured to be in electrical contact with the plate 9, but it is possible to use an insulating material for the plate cylinder 5 to directly supply electricity to the plate 9. It may also be used as a configuration.

The plate 9 mounted on the plate cylinder 5 acts as an electrode paired with the roller 4, and as shown in FIG. form and compose. In other words, a pattern is formed due to the difference in conductivity on the plate surface that comes into contact with the ink.
It is sufficient if it is possible to conduct electricity to highly conductive parts.

Ink 10 suitable for printing using the apparatus of the present invention
is an ink whose adhesion changes depending on the polarity of the applied voltage; for example, it is sticky when no voltage is applied;
Examples include inks whose adhesive properties disappear when voltage is applied. This ink is energized by applying voltage.
The ink electrolyzes and generates gas, changing its adhesion from adhesive to non-adhesive.

In this case, the ink is adjusted to have adhesive properties,
When a voltage is applied, the ink generates gas near one of the electrodes, and this gas prevents the ink from adhering to the electrode. In order for the ink to electrolyze and generate gas, the ink contains a solvent such as water, alcohol, glycol, or a solvent in which an electrolyte is dissolved. The lower the electrical resistance of the ink, the better, and it is preferable to set the volume resistance to 106 Ω・Cm or less. If the 0 volume resistance exceeds 10′ Ω・am, the amount of current will decrease, or to prevent the amount of current from decreasing. This requires high voltage, which is undesirable.

The above-mentioned ink has a weak cohesive force with liquids such as water and alcohol, and suitable adhesiveness cannot be obtained. Also, this ink is
For example, it is preferable that when ink is deposited to a thickness of 2 mm on a vertically erected platinum-plated stainless steel plate, the ink is substantially retained on the platinum-plated stainless steel plate; , ink is sandwiched between two platinum-plated stainless steel plates so that the thickness of the ink is 2 mm, and when the two platinum-plated stainless steel plates are separated from each other with no voltage applied, the ink is the same on both plates. It is preferable that the ink adheres to a certain degree.
Basically, it is composed of a liquid dispersion medium and inorganic or organic fine particles. The fine particles in the ink make it easier to cut the ink and improve the resolution of the image. Such an ink is an amorphous solid of a colloidal sol and is a non-Newtonian fluid in terms of fluidity.

The liquid dispersion medium used in the above ink includes ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol (weight average molecular weight, approximately 1
00 to i, ooo), ethylene glycol methyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, methyl calpitol, ethyl calpitol, butyl calpitol, ethyl calpitol acetate, diethyl calpitol,
Triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, propylene glycol monomethyl ether, glycerin, triethanolamine, formamide, dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone,
1.3-dimethylimidazolidinone, N-methylacetamide, ethylene carbonate, acetamide, succinonitrile, dimethyl sulfoxide, sulfolane, furfuryl alcohol, N, N-dimethylformamide, 2
-Ethoxyethanol, hexamethylphosphoric triamide (hexamethylphosphoric triamide), 2-nitropropane, nitroethane, γ-butyrolactone, propylene carbonate, ■, 6-hexandriol, dipropylene glycol, hexylene glycol, etc. alone Alternatively, a mixed solvent of two or more types can be used. The liquid dispersion medium is preferably contained in an amount of 40 to 95 parts by weight, more preferably 60 to 85 parts by weight, per 100 parts by weight of the ink.

More preferred liquid dispersion media include water, alcohols such as methanol and ethanol, solvents with hydroxyl groups such as glycerin, ethylene glycol and propylene glycol, or solvents in which electrolytes such as sodium chloride and potassium chloride are dissolved. In particular, when water or a water-containing liquid dispersion medium is used, hydrogen gas is easily generated on the cathode side, which is preferable.When water and another liquid dispersion medium are mixed, the water content is It is preferably 1 part by weight or more, more preferably 5 parts by weight or more per 100 parts by weight.

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 part by weight, based on 100 parts by weight of the ink material.
It can be contained in an amount of from 1 to 50 parts by weight, particularly from 1 to 20 parts by weight.

Such polymers include plant-based polymers such as guar gum, locust bean gum, gum arabic, taragant, carrageenan, pectin, mannan, and starch:
xanthan gum, dextrin, succinoglucan,
Microbial polymers such as curdlan; Animal polymers such as gelatin, casein, albumin, and collagen; Cellulose polymers such as methyl cellulose, ethyl cellulose, and hydroxyethyl cellulose, or starch polymers such as soluble starch, carboxymethyl starch, and methyl starch; Semi-synthetic polymers such as alginic acid polymers such as propylene glycol alginate and alginates, and their geosaccharide derivatives; Vinyl polymers such as polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, carboxyvinyl polymers, and sodium polyacrylate; Others Polyethylene glycol, ethylene oxide, propylene oxide block copolymer, alkyd resin, phenolic resin, epoxy resin,
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 polypden.

The fine particles contained in the ink include metals (Au, Ag
, Cu, etc.) particles, sulfides (zinc sulfide ZnS, antimony sulfide Sb2 S3, potassium sulfide 2S, calcium sulfide CaS, germanium sulfide GeS, cobalt sulfide Co
S, tin sulfide SnS, iron sulfide FeS, copper sulfide CIJ2S
.

Manganese sulfide MnS, molybdenum sulfide Mo2 S@, etc.)
Particles, silicic acid (orthosilicic acid H, 5i04, metasilicic acid H2Sr et al., mesonicic acid H2S120s, mesotrisilicate H2Si et al., mesotetrasilicic acid)! 6S14011 etc.) particles, polyamide resin particles, polyamideimide resin particles,
Iron hydroxide particles, aluminum hydroxide particles, fluorinated mica particles, polyethylene particles, montmorillonite particles, fluororesin, silica, carbon fluoride, titanium oxide, carbon black,
Carbon fluoride and various polymer particles used as electrophotographic toners can also be used.

The above-mentioned fine particles have an average particle diameter of 100 μm or less,
Preferably, particles with a diameter of 0.1 μm to 20 μm, especially those with a diameter of 10 μm or less, can be used.Furthermore, such fine particles are contained in the ink in an amount of 1 part by weight or more, preferably 3 parts by weight to 901 parts by weight, and more preferably 1 part by weight or more per 100 parts by weight of the ink. can be contained in an amount of 5 to 60 parts by weight.

In a preferred specific example of the ink, considering the viscoelastic properties of the ink, it is preferable to use swellable fine particles that can retain the above-mentioned liquid dispersion medium as the fine particles in the ink. Examples of such swellable fine particles include: Na-montmorillonite, Ca-montmorillonite, 3-octahedral synthetic smectite, Na-hectorite, Li-hectite, Na-teniolite, fluoride mica such as Na-tetrasilicic mica and Li-duolite, synthetic mica,
There are silica etc.

The above-mentioned fluorinated mica can be represented by the following general formula (1) 6 General formula (1) % formula %) In the above formula, W is Na or Li, and X and Y are Mg2-F
Hexacoordination ions such as e", Ni", Mn2◆, Fe", LJ.

Z represents an ion having a coordination number of 4, such as A134, Si", Ge", Fe", B34, or a combination thereof (Al1"/Si'.).

The average particle diameter of the swellable fine particles is preferably 100 μm or less, more preferably 1 to 20 μm, and preferably 110 μm or less.

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 coloring material, the content of the coloring material is 0.00 parts by weight per 100 parts by weight of the ink.
The amount is preferably 1 to 40 parts by weight, more preferably 1 to 20 parts by weight, and a color-forming compound that develops color upon application of voltage may be contained instead of or together with the colorant.

In addition, electrolytes that give conductivity to ink, thickeners,
It can contain a thinning agent, a surfactant, etc. Furthermore, it is also possible for the above-mentioned fine particles themselves to also function as a coloring material.

The ink 10 having the above-described structure is put between the rollers 1 and 2 as shown in FIG. 1, and the ink 10 is supplied onto the plate 9 by the rollers 1 to 4. At the same time, a voltage is applied from a power source 11 between the plate 9 with the ink 10 interposed therebetween and the roller 4 (the roller 4 is the anode, the plate 9 is the cathode), and then the ink 10 in contact with the conductive base material of the plate 9 becomes conductive. The ink image is formed only on the insulating pattern on the plate 9 by changing the adhesion to the adhesive base material to non-adhesion. The applied voltage at this time is practically preferably a DC voltage of 3 to 1 OOV, more preferably a DC voltage of 5 to 80V, and an AC bias voltage may be supplementarily applied.

Next, the ink image on the plate 9 is transferred onto the blanket cylinder 6 which rotates in the direction of arrow F while being in pressure contact with the plate 9. Furthermore, the ink image is transferred onto a recording medium 8 (dense cloth, metal sheet, etc.) that passes between the impression cylinder 7 rotating in the direction of arrow G while being in pressure contact with the blanket cylinder 6, thereby forming an ink image on the recording medium 8. do. In some cases, the ink image on the plate 9 may be directly transferred onto the recording medium 8.

Example 1 0-rollers 1 to 3 were made of stainless steel and had a diameter of 34 mm and a width of 80 mm. Roller 4 was made of elastic graphite (
Manufactured by Koa Oil, volume resistance 1Ω, bulk density 1.15)
Mix 20 parts with 80 parts of polyfluoroethylene, knead the mixture (thickness: 5 mm), and place it on a stainless steel shaft (diameter: 34 m).
m, width 80 mm) was used. The elastic graphite body described here is produced by nitrating carbonaceous mesophase or coke produced during the heat treatment process of heavy bituminous materials, dissolving this nitrate in an alkali, and adding acid to precipitate it. It is obtained by foaming and graphitizing the foam.

The plate cylinder 5 had a diameter of 80 IMI, a width of 80 III m, and was made of stainless steel, and the plate 9 had an insulating pattern formed with photoresist on a copper plate with a thickness of 0.1 mm.

The gap between rollers 1 and 2 is 0.5 mm, the gap between rollers 2 and 3 is 0.1 mm, and roller 4
was brought into contact with roller 3 and plate 9, and rollers 1 to 5 were driven by a motor.

Ink 10 includes 200 g of glycerin and lithium teniolite (average particle size 2.5 μm, LiMg+Li (
SiaO+l1)F2) 140 g and cyan pigment (manufactured by Bayer AG, 5upranol Cya) as a coloring agent.
nine 78F) l Og in a homogenizer for 30 minutes at a rotational speed of 10'rpm, then add 200g of water.
A gray amorphous solid sol ink was prepared by adding and mixing on a roll mill.

After adding the ink 10 as shown in FIG.
-7 were rotated at 100 mm/sec in the direction of arrow A-G, respectively.

After visually confirming that the ink 10 was uniformly coated on the roller 4, the roller 4 was brought into contact with the plate 9. At this time, a DC voltage of 30 V was simultaneously applied using the conductive base material of the plate as a cathode and the roll 4 as an anode.

As a result, the ink adhered only to the insulating pattern of the conductive base material of plate 9, and a large number of prints with high image quality and no sharp fogging were obtained. Furthermore, no peeling or unevenness was observed on the rubber material on the surface of the roller 4.

Example 2 Printing was carried out in the same manner as in Example 1, except that the elastic graphite used in 0-Lar 4 was replaced with an elastic graphite (manufactured by Kowa Oil Co., Ltd., bulk density 1.0, volume resistance 1Ωam).

As in Example 1, many prints with sharp, fog-free image quality were obtained. Furthermore, no peeling or the like was observed on the rubber material on the surface of the roller 4.

Example 3 The elastic graphite used in 0-Lar 4 was made by dispersing conductive carbon in ethylene propylene rubber (volume resistance 5.0
Printing was carried out in the same manner as in Example 1, except that Ωam) was used.

As in Example 1, many prints with sharp, fog-free image quality were obtained. Furthermore, no peeling or the like was observed on the rubber material on the surface of the roller 4.

Example 4 The roller 4 of Example 1 was made by dispersing conductive carbon in nitrile rubber using elastic graphite (volume resistance 4.5
Ωam) was used for rollers 1 to 4, and a configuration was adopted in which electricity could be applied between rollers 1 and 2, between rollers 2 and 3, between rollers 3 and 4, and between roller 4 and plate 5 (Fig. 3). ) Printing was carried out in the same manner as in Example 1 except for the following. After that, the pressure contact between the roll 4 and the plate roll 5 is released (a state in which they are not in electrical contact), and then the roll 4 is used as a cathode,
The roll 3 was used as an anode, and 30 V was applied from the power source 12 while rotating in the arrow direction and the C direction, respectively. Then, all the ink on roll 4 moved onto roll 3. In this state, roll 4 is separated from roll 3 so that they are not in electrical contact with each other), and then roll 3 is used as a cathode, and roll 2 is used as a cathode.
was used as an anode, and 30V was applied from the power source 13 while rotating in the direction of arrow C and the direction of arrow B, respectively. Then, all the ink on roll 3 moved onto roll 2. Remain in this state.

After the roll 3 is separated from the roll 2 so that it is not in electrical contact with the roll 2), the roll 2 is set as the cathode and the roll 1 is set as the anode, and 30V is applied from the power supply 14 while rotating in the direction of arrow B and in the direction of arrow B, respectively. did. Then, all the ink on roll 2 moves onto roll l, and eventually roll 2. 3. 4
All of the above ink was collected on roll 1. The single operation was repeated, but roll 1. 2. 3. No phenomena such as peeling of the surface of 4 were observed.

Comparative Example 1 Synthetic natural rubber (IR) was used instead of the elastic graphite of Example 1.
Carbon is dispersed inside (volume resistance 3.0Ωcm
) was used to test the soap in the same manner as in Example 1. Initially, many prints with sharp image quality were obtained, but after repeating the process several times, the surface of the roll peeled off and became uneven, resulting in uneven images. A disturbance occurred. Since the surface of the roll 4 became acidic, it seems that the synthetic natural rubber (IR) was less dissolved.

Comparative Example 2 Instead of the elastic graphite of Example 1, styrene rubber with carbon dispersed therein (volume resistance: 3.7 Ωcm) was used. As a result, as in Comparative Example 1, disturbances appeared in the image.

[Effects of the Invention] As explained above, according to the present invention, at least one of the electrodes contains conductive carbon and/or graphite and a rubber material that does not dissolve even in an acidic or alkaline atmosphere. An image forming apparatus is provided.

[Brief explanation of drawings]

FIGS. 1 and 3 are schematic diagrams of examples of image forming apparatuses of the present invention, and FIG. 2 is schematic diagrams of examples of plates that can be used in the image forming apparatuses of the present invention. 1 to 4: Roller 5; Plate cylinder 6: Blanket cylinder 7: Impression cylinder 8: Recorded body 9: Plate 9a, conductive base material 9b/Insulation pattern 10: Ink 11 to 14: Power supply

Claims (1)

[Claims] 1. A voltage is applied between a pair of electrodes and the electrodes in contact with the ink, thereby supplying ink that adheres only to one electrode and does not adhere to the other electrode between the pair of electrodes. means,
and an image forming apparatus having means for applying a voltage between the pair of electrodes, wherein at least one of the electrodes is made of a) conductive carbon and/or conductive graphite and b) nitrile rubber, butyl rubber, chloroprene rubber, or ethylene propylene rubber. , chlorosulfonated polyethylene, chlorinated polyethylene, and polyfluoroethylene resin.