JPH03294363A - Production of electrically conductive powder ink - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a thermal transfer image forming apparatus having a process of forming an image by a thermal transfer printing method and a process of recycling an ink sheet using electrostatic force, so-called recycled thermal transfer. This invention relates to improvements in powder ink used in image forming apparatuses.

[Prior Art] Japanese Patent Application No. 63-36113 describes a thermal transfer image forming apparatus having a step of forming an image using a conventional thermal transfer printing method and a step of regenerating an ink sheet using electrostatic force, and a special patent application for a method of regenerating an ink sheet. Japanese Patent Application No. 63-36115, Japanese Patent Application No. 1-222031, Japanese Patent Application No. 1983-222031, as powder ink
214441 etc. have been proposed.

[Problems to be Solved by the Invention] However, powder ink used in conventional regenerative thermal transfer image forming apparatuses has been made conductive by internally adding and mixing conductive fine powder or by externally adding conductive fine powder. I was worried. When considering the conductive path in powder ink, in order to make it conductive, individual particles must be mixed in such a way that they are in contact with each other, and other than those with a large aspect ratio such as carbon black or carbon fiber, there is no sufficient In order to ensure conductivity, it is necessary to add a large amount of several tens of wt % to the powder ink, which poses problems such as difficulty in kneading and an increase in the melt viscosity of the ink, making printing difficult. Furthermore, since the conductivity imparted by carbon black is itself colored, when a chromatic colored powder ink is produced, the color of the powder ink becomes cloudy.
When conductive using conductive titanium oxide or indium tin oxide fine powder, there was a problem with the color characteristics of the powder ink, such as white turbidity or pale yellow turbidity.

The present invention is intended to solve these problems, and its purpose is to provide a powder ink that has less influence on the ink properties of the powder ink, such as ink color and printability, and that is easy to manufacture. The purpose is to provide a manufacturing method.

[Means for Solving the Problems] The method for producing conductive powder ink of the present invention provides a thermal transfer image forming apparatus having the steps of forming an image by a thermal transfer printing method and recycling an ink sheet using electrostatic force. In the method for producing conductive powder ink used in It is characterized by forming a conductive layer made of a conductive polymer on the inner core surface of the body ink.

The details of the present invention will be shown below with reference to Examples.

[Example 1] FIG. 1 is a flowchart of the method for producing conductive powder ink of the present invention.

The binder resin 1, the coloring material 2, and the polymerization catalyst 3 are pulverized into a powder ink inner core 7 by kneading 5 and pulverization 6.

When printing at a low temperature, the binder resin 1 may be a vegetable wax such as candelilla wax or carnauba wax, an animal wax such as beeswax or lanolin, a mineral wax such as montan wax, paraffin wax, microcrystalline wax, etc. petroleum waxes, polyethylene waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch waxes, modified waxes such as montan wax derivatives and paraffin wax derivatives, hydrogenated waxes such as hydrogenated castor oil and hydrogenated castor oil derivatives, fatty acids, acid amides, and esters. , synthetic waxes such as ketones, and other waxes are used. When printing at high temperatures, use acrylic resins such as polyacrylate and polymethacrylate, styrene resins such as polystyrene and poly-1-methylstyrene, butyral resins, polyester resins, polycarbonate resins, cellulose resins, polyarylate resins, polyethylene resins, polypropylene resin, vinyl acetate resin,
and thermoplastic resins of these copolymers are used, and these may be used alone or in combination.

Colorant 2 is a colorant for coloring conductive powder ink.For yellow, benzidine yellow and disazo yellow.For red, carmine 6B, Lake Red C, Bigmendo Scarlet, and quinacridone.For blue, phthalocyanine blue and inxlen blue. For black color, facial dyes such as carbon blacks such as furnace black, lamp black, and acetylene black are used.

It is also possible to add a dispersant to disperse the colorant 2 in the binder resin 1, and examples of the dispersant include alkylbenzenesulfonates, alkylnaphthalenesulfonic acids,
Anions such as higher alcohol sulfonate, fatty acid amide conductor sulfate, polyethylene glycol alkyl allyl ether sulfonate, cations such as alkylpyridinium chloride, trimethylstearylammonium chloride, alkylphenol polyethylene ether, dialkyl succinate, sorbitan alkaline Nonions such as chelates, polyoxyethylene alkylphenol ethers, polyacrylate derivatives, polymethacrylate derivatives, polycarboxylic acid salts such as maleic anhydride copolymers, trussperse super dispersants, etc. are used alone or in combination. be able to. Furthermore, the coloring material 2 can be treated with a titanium-based, silane-based, chromium-based, aluminum-based coupling agent, and the like.

Polymerization catalyst 3 is a catalyst for polymerizing monomer 4, and contains iron chloride (
III), molybdenum (V) chloride, ruthenium (I) chloride
Oxidizing agents such as transition metal halides such as II), Lewis acids such as polyphosphoric acid, and peroxides are used.

For kneading 5, a screw extruder is used in a continuous type, a Banbury mixer or the like is used in a batch type, and a homogenizer, colloid mill, ball mill, etc. is used in a wet mixed mixer. When a thermally decomposable compound such as a peroxide or a volatile Lewis acid is used as the polymerization catalyst 3, wet kneading without heating is effective.

The finely pulverized material 6 is pulverized into a fine powder having a particle size of 5 to 20 μm using a jet mill, a cutter mill, an angular mill, a ball mill, or the like.

The powder ink inner core 7 and the monomer 4 are mixed in a gas phase, and the polymerization catalyst on the surface of the powder ink 7 comes into contact with the vapor of the monomer 4 to initiate gas phase oxidation polymerization, which creates electrical conductivity on the surface of the powder ink. A conductive layer made of a conductive polymer is formed, and conductive powder ink 9 is created. As the monomer 4, aniline, thiophene, virol, furan, and derivatives thereof are used, and the reaction system is adjusted from a normal pressure reaction system to a reduced pressure reaction system depending on the vapor pressure of each monomer. In addition, many conductive polymers have a molecular extinction coefficient of 10
In order to obtain a chromatic color of 3 to 105, the conductive layer must have a thickness that does not affect the color of the powder ink inner core 7, except when the conductive layer is the same color as the underlying powder ink inner core 7. However, since printing is performed after melting the conductive powder ink to form an ink sheet, there is no problem with the difference in color depending on the shape of the conductive powder ink, and the conductive polymer formed by vapor phase oxidation polymerization The thickness of the layer is thin and uniform, submicron or less, so color turbidity after melting is not a problem.

FIG. 2 is a schematic diagram of a thermal transfer image forming apparatus using the powder ink of the present invention.

In the step of forming an image by a thermal transfer printing method, an ink sheet 13 having an ink layer 12 on an insulating support 11 is moved in an ink sheet conveying direction 14 while a thermal head 15 applies ink onto an image forming body 16. is transferred to form an ink transfer portion 17 and an ink peeling portion 18 in which the insulating support 11 is exposed on the ink sheet. If the ink is not transferred, an untransferred area 19 remains on the ink sheet 13. The thermal transfer image forming apparatus has an image forming object 1
6 in the scanning direction 20.

Following image formation, the process of regenerating the ink peeling part 18 on the ink sheet includes a process of selectively attaching the conductive powder ink 9 to the ink peeling part 18 and a process of fixing the conductive powder ink 9 to form an ink layer. 12.

An electrode A arranged at a predetermined distance from a powder ink supply roller 23 formed by laminating a dielectric layer 22 on a conductor 21.
24, the conductive powder ink 9 is supplied, and a voltage v1 is applied between the conductor 21 and the electrode A24 by the power source A25. By applying the voltage v1, the powder ink supply roller 23
An electrical conduction path is formed in the conductive powder ink 9 in the gap between the electrode A24 and the conductive powder ink 9, and a charge Q1 is injected into the conductive powder ink 9 in contact with the dielectric layer 22 of the powder ink supply roller 23. . However, the conductive powder ink 9 on the conductive powder ink 9 in contact with the powder ink supply roller 23 only serves as an electrical conduction path and no charge is injected into the powder ink supply roller 23. Only the contacting conductive powder ink 9 is transferred to the powder ink supply roller 2 due to electrostatic force.
3. Adhere in a thin layer on top.

The electrode B26 is placed in contact with the insulating support 11 of the ink sheet 13, and the electrode B26 is placed in contact with the insulating support 11 of the ink sheet 13.
Conductive powder ink 9 is applied to the ink sheet 13 on the opposite side of 26.
By arranging the powder ink supply roller 23 that sequentially supplies the powder ink upward, and applying the voltage v2 between the electrode B26 and the powder ink supply roller 23 by the power source B27, the conductive powder that has come into contact with the ink peeling section 18 is removed. Ink 9 has voltage v1
, v2 and the electric capacitances C1 and C2 (C1 is the electric capacity in the dielectric layer 22 of the powder ink supply roller 23, and C2 is the electric capacity in the insulating support 11). Powder ink supply roller 2
3, and Q2 represents the charge induced in the electrode B26).

Here, the restraining force F1 of the conductive powder ink 9 to the powder ink supply roller 23 and the adhesion force F2 to the ink peeling part 18
is F 1 =k I IQ 12/D 12F2=2*
It is expressed as Q22/D22. (kl and k2 are constants, Dl is the thickness of the conductive layer 22 of the powder ink supply roller 23, and D2 is the thickness of the insulating support 11) If the restraining force Fl<adhesion force F2, the conductive powder It becomes possible to attach the ink 9 to the insulating support 11. That is, by appropriately selecting the voltages v1 and v2 and the capacitances C1 and C2, the conductive powder ink 9 is transferred to the ink peeling section 1.
8 can be attached. On the other hand, ink untransferred area 1
Regarding the conductive powder ink 9 in contact with 9, the charge Q2
Since the conductive ink untransferred portion 19 has a charge Q1 and the conductive powder ink 9 has a charge Q1, the conductive powder ink 9 is attached to the powder ink supply roller 2p. The conductive powder ink 9 replenished only to the ink peeling part 18 of the ink sheet 13 in this way is transferred to the heat roller 28.
The ink sheet 13 is fixed onto the insulating support 11 by the support roller 29 to become the ink layer 12, and the ink sheet 13 is recycled.

The untransferred conductive powder ink remaining on the powder ink supply roller 23 is scraped off by a cleaning blade 30, and the residual charge on the powder ink supply roller 23 is neutralized by a static elimination brush 31.

The insulating support 11 of the ink sheet used in the present invention is made of polyethylene terephthalate, polyaramid,
A resin film such as polyimide can be used. As the thermal head 15, in addition to heads used in fused heat transfer printing devices, stylus heads used in energized heat transfer printing devices can also be used. A current-carrying layer is formed on the opposite side of the ink layer across the sheet. As the image forming object 16, thermal transfer paper, plain paper, OHP sheet, etc. are used.

[Example 1 Cocyan conductive powder ink binder resin microcrystalline wax 5 g Ethylene-vinyl acetate copolymer 5 g Ethylene-maleic anhydride copolymer 0 g Colorant phthalocyanine blue 5 g Polymerization catalyst iron (III) chloride 5 g The above mixture was wet-kneaded in a toluene-cyclohexanone mixed solvent using a homogenizer, dried and solidified, and then pulverized into a fine powder of 5 to 20 μm using a jet mill to obtain a powder ink inner core. The entire inner core of the powder ink was placed in a reaction vessel equipped with a vacuum pump, and pyrrole vapor was introduced as a monomer under reduced pressure to perform gas phase oxidation polymerization. Polypyrrole was generated on the surface of the powder ink to form a conductive layer. A cyan conductive powder ink was obtained. The polymerization reaction was controlled by adjusting the temperature of the reaction vessel and the introduction time of roll steam.

Yellow conductive powder ink A yellow conductive powder ink was prepared in the same manner as the cyan conductive powder ink using benzidine yellow as a coloring material.

Magenta conductive powder ink A magenta conductive powder ink was prepared in the same manner as the cyan conductive powder ink using Lake Red C as a coloring material.

[Example 2] Yellow conductive powder ink binder resin microcrystalline wax 0 g Ethylene-vinyl acetate copolymer 0 g Acrylic acid-1so-butyl acrylate copolymer 0 g Colorant benzidine yellow 5 g Polymerization catalyst ammonium peroxodisulfate g The above mixture was subjected to wet mixing using a homogenizer in a toluene-methyl cellulose mixed solvent, dried and solidified, and then pulverized into a fine powder of 5 to 20 μm using a jet mill to obtain a powder ink inner core. The entire inner core of the powder ink was placed in a reaction vessel equipped with a vacuum pump, and aniline vapor was introduced as a monomer under reduced pressure to perform gas phase oxidation polymerization. Due to polymerization, polyaniline was produced on the surface of the powder ink, and at the same time, acrylic acid in the core of the powder ink was doped into the polyaniline to form a conductive layer, resulting in yellow conductive powder ink. 0 Control of the polymerization reaction The temperature of the reaction vessel and the introduction time of aniline vapor were adjusted.

Magenta conductive powder ink A magenta conductive powder ink was prepared in the same manner as the yellow conductive powder ink using Lake Red C as a coloring material.

Cyan conductive powder ink A cyan conductive powder ink was prepared in the same manner as the yellow conductive powder ink using phthalocyanine blue as a coloring material.

[Comparative Example 1] Yellow conductive powder ink binder resin microcrystalline wax 7 g Ethylene-vinyl acetate copolymer 5 g Methacrylic acid-butyl acrylate copolymer 0 g Colorant benzidine yellow 5 g Conductivity imparting agent Ketchen Black 3g The above mixture was mixed and kneaded using a patch type kneader, and then pulverized into a fine powder of 5 to 20 μm using a jet mill to prepare a yellow conductive powder ink.

Magenta and cyan conductive powder inks were prepared in the same manner as the yellow conductive powder ink, using Lake Red C for magenta and Phthalocyanine Blue for cyan.

[Comparative Example 2] Yellow conductive powder ink binder resin microcrystalline wax 3 Ethylene-vinyl acetate copolymer methacrylic acid-butyl acrylate copolymer g Colorant benzidine yellow 5g Conductivity imparting agent ITO (indium tin oxide) 0 g The above mixture was mixed and kneaded using a batch mixer, and then pulverized into a fine powder of 5 to 20 μm using a jet mill to prepare a yellow conductive powder ink.

Magenta and cyan conductive powder inks were prepared in the same manner as the yellow conductive powder ink using Lake Red C for magenta and Phthalocyanine Blue for cyan.

Table 1 shows the electrical resistance values of the conductive powder inks prepared in Example 1.2 and Comparative Example 1.2.

Table 1 As shown in Table 1, the conductive powder ink of the embodiment of the present invention has a resistance value of 10 which can be used in a recycled thermal transfer image forming apparatus.
It is 6Ω·cm or less. Furthermore, as a result of printing with the thermal transfer image forming apparatus shown in Fig. 2, the ink layer in which the conductive powder ink was fixed onto the insulating support using a heat roller did not suffer from color turbidity due to the conductive polymer. , good printed matter was obtained. Furthermore, since the resistance value of the conductive powder ink was sufficiently small, selective adhesion of the conductive powder ink to the ink-removed portion was performed. Comparative example 1, which is a conventional example, compared to this
．． The conductive powder ink of No. 2 has a resistance value of 106 Ω・cm, but in the case of Comparative Example 1, Ketchen Black has a resistance value of 3W.
t%, and despite the addition of yellow, magenta, and cyan colorants, it is almost completely black and cannot be used as a chromatic powder ink.In addition, in the case of Comparative Example 2, ITO Since 70wt% of fine powder was added, printing was performed using the thermal transfer image forming apparatus shown in Fig. 2.
Since the ink had a high melt viscosity of 1*10'cps or more at 100° C., voids were observed in the ink transfer area on the image forming body after printing.

Furthermore, since a large amount of hard fine ITO powder was added to the powder ink, wear of the paddle and barrel of the kneader and wear of the heat roller of the thermal transfer image forming apparatus was observed. However, in order for ITO fine particles to come into contact with each other in powder ink when imparting conductivity with ITO, it is necessary to
It is necessary to add 0 wt % or more, and if it is less than this, conductivity will not develop and the amount added cannot be reduced.

[Effects of the Invention] As described above, according to the present invention, a conductive image forming apparatus used in a thermal transfer image forming apparatus having a step of forming an image by a thermal transfer printing method and a step of recycling an ink sheet using electrostatic force. In the method for producing powder ink, a powder ink inner core containing a polymerization catalyst and a monomer that is a raw material for a conductive polymer are mixed in a gas phase, and conductivity is applied to the surface of the powder ink inner core using a gas phase oxidation polymerization method. By forming a conductive layer made of a conductive polymer, a conductive powder ink having a resistance value usable in a regenerative thermal transfer image forming apparatus was obtained. In addition, since the conductive layer created by gas phase oxidation polymerization is thin and uniform, color turbidity does not occur in chromatic conductive powder inks, and good printed matter without voids etc. can be obtained when printed on actual machines. , it has become possible to make the powder ink conductive without affecting its properties. Furthermore, it is easy to manufacture as there is no wear during the powder ink kneading process.
Resistance can be easily controlled by adjusting the polymerization conditions of the conductive polymer in the conductive layer, making it possible to equalize the resistance values of each color, making it possible to uniformly reproduce the ink sheet and stabilize printing quality.

The powder ink and printing device of the present invention can be applied to devices using an image forming method that includes a step of forming an image using a thermal transfer method and a step of recycling and using an ink sheet, such as a printer, a copying machine, a facsimile machine, etc. It can also be applied to a wide range of other applications.

[Brief explanation of the drawing]

FIG. 1 is a flowchart of the method for manufacturing conductive powder ink of the present invention. FIG. 2 is a schematic diagram of a thermal transfer image forming apparatus using the powder ink of the present invention. 1... Binder resin 2 ・ 3 ・ 4 ・ 5 ・ 6 ・ 7 ・ 8 ・ 9 ・ 11 ・ 12 ・ 13 ・ 14 ・ l 5 ・ 16 ・ 17 ・ 18 ・ 19 ・ 20 ・ 2 l ・ 22 ・ ・Coloring material, polymerization catalyst, monomer, kneading, fine pulverization, powder ink inner core, gas phase oxidation polymerization, conductive powder ink, insulating support, ink layer, ink sheet, ink sheet transport direction, thermal head, Image forming body, ink transfer section, ink peeling section, ink untransferred section, scanning direction, conductor, conductor 23 ・ 24 ・ 25 ・ 26 ・ 27 ・ 28 ・ 29 ・ 30 ・ 31 . . . Powder ink supply Roller・Electrode A・Power source A・・Electrode B・Power source B・・Heat roller, support roller, cleaning blade, static elimination brush or more

Claims (1)

[Claims] In a method for producing conductive powder ink used in a thermal transfer image forming apparatus that includes a step of forming an image by a thermal transfer printing method and a step of regenerating an ink sheet using electrostatic force, a powder ink containing a polymerization catalyst is used. A conductive product characterized by mixing the inner core and a monomer that is a raw material for the conductive polymer in a gas phase, and forming a conductive layer made of the conductive polymer on the surface of the powder ink inner core using a gas phase oxidation polymerization method. A method for producing a powder ink.