JPH03294362A - Colored electrically conductive powder ink - Google Patents

Abstract

PURPOSE:To obtain the title powder ink providing prints of clear color, having no color turbidity in an ink layer, by externally adding a colorant made electrically conductive by graft polymerization of an electrically conductive polymer to the surface of inner shells of powder ink to form a colored electrically conductive layer. CONSTITUTION:A colorant such as Benzidine Yellow or Indanthrene Blue made electrically conductive by graft polymerization of an electrically conductive polymer is externally added to the outer periphery of inner shells 3 of powder ink comprising a binder resin 1 such as Candelilla wax or lanolin and a dispersant 2 and a colored electrically conductive layer 4 is formed to give the objective ink useful for a heat transfer image forming device having a process of making image by the heat transfer printing method and a process of renewing an ink sheet by using electrostatic force.

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. Patent application No. 1983-36115, Japanese patent application No. 1-222031, Patent application No. 1983-222031 as powder ink
214441 etc. have been proposed.

[Problems to be Solved by the Invention] However, the color conductive powder ink used in conventional regenerative thermal transfer image forming apparatuses has not been made conductive by internally mixing or externally adding colorless or light-colored conductive fine powder. Ta. When considering the conductive path in powder ink, in order to make it conductive, it is necessary to mix individual fine powders so that they are in contact with each other, and to ensure sufficient conductivity, several tens of wt.
%, it is necessary to add a large amount of the ink, and there are problems such as difficulty in crosstalk and an increase in the melt viscosity of the ink, which makes fixing and printing difficult. Furthermore, when the powder ink is made conductive by external addition, the color of the inner core of the powder ink is hidden and the color remains cloudy even after it is melted to form an ink layer.

The present invention is intended to solve these problems, and its purpose is to provide a conductive method that does not cause ink color turbidity and has little effect on the ink properties of powder ink such as fixability and printability. provides a color conductive powder ink.

[Means for Solving the Problems] The conductive powder ink of the present invention is used in a thermal transfer image forming apparatus that has a step of forming an image by a thermal transfer printing method and a step of recycling an ink sheet using electrostatic force. The color conductive powder ink is characterized by having a colored conductive layer formed of a coloring material made conductive by graft polymerization of a conductive polymer on the surface of the powder ink inner core.

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

[Example] FIG. 1 is a cross-sectional view of the color conductive powder ink of the present invention.

A conductive layer 4 is formed on the outer periphery of a powder ink inner core 3 made of a binder resin 1 and a dispersant 2, forming a color conductive powder ink 5.

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, paraffin wax conductors, hydrogenated waxes such as hydrogenated castor oil and hydrogenated castor oil derivatives, fatty acids, acid amides, Waxes such as synthetic waxes such as esters and ketones 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.

Examples of the dispersant 2 include anions such as alkylbenzene sulfonates, alkylnaphthalenesulfonic acids, higher alcohol sulfonates, fatty acid amide derivative sulfuric acid esters, polyethylene glycol alkyl allyl ether sulfonates, alkylpyridinium chloride, trimethylstearylammonium chloride, etc. cations, nonions such as alkylphenol polyethylene ether, dialkyl succinate, sorbitan alkylate, polyoxyethylene alkylphenol ether,
Polyacrylate derivatives, polymethacrylate salts, polycarboxylic acid salts such as maleic anhydride copolymers, trussperse super dispersants, titanium-based, silane-based, chromium-based, aluminum-based coupling agents, etc. The dispersant 2, which can be used alone or in combination, is used to disperse the conductive coloring material used in the conductive layer 4 into the ink layer when the color conductive powder ink 5 is melted and the ink layer is formed. used.

The conductive layer 4 is made of a conductive coloring material. Conductive colorants include benzidine yellow, disazo yellow, metal salt azo yellow for yellow colors, Carmen 6B, Lake Red C, Pigment Scarlet, and Quinacridone for red colors, and phthalocyanine blue and ink-threne blue for blue colors. It is made conductive by graft polymerization of polymers. In the case of lake pigments, the coloring material is made conductive by utilizing a complex formation reaction between free functional groups such as carboxylic acid or sulfonic acid on the surface of the pigment and a conductive polymer.1 Coloring materials with an inert surface are titanium-based. , silane-based, chromium-based, aluminum-based coupling agent treatment, transition metal halides such as iron (III) chloride, molybdenum (V) chloride, ruthenium (III) chloride, Lewis acids such as sulfuric acid, peroxides, etc. After milling a polymerization initiator such as an oxidizing agent, aniline, thiophene, virol, furan, etc., and their derivatives are oxidatively polymerized in a liquid or gas phase to make the material conductive.

The powder ink inner core is created by mixing the binder resin 1 and the dispersant 2 and pulverizing them. For crosstalk, a screw extruder is used in a continuous type, a Banbury mixer is used in a patch type, and a homogenizer, colloid mill, ball mill, etc. is used in a wet type. Further, it is also possible to add a colorant to the powder ink inner core in addition to the colorant used in the conductive layer, and in that case, the colorant is added during kneading. Fine grinding is done by jet mill,
This is carried out using a cutter mill, an angular mill, a ball mill, etc., and is pulverized into a fine powder with a particle size of 5 to 20 μm.

The conductive layer 4 is formed by coating the surface of the powder ink inner core 3 with a conductive coloring material. As the external addition method, a mechanochemical method using a ball mill, an ong mill, etc. is used in a dry method, a spray drying method, a treatment method with a coupling agent such as titanium-based, silane-based, chromium-based, aluminum-based, etc. are used in a wet method.

FIG. 2 is a schematic diagram of a thermal transfer image forming apparatus using the color conductive 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 step of regenerating the ink peeling portion 18 on the ink sheet includes a step of selectively attaching the color conductive powder ink 5 to the ink peeling portion 18 and a step of fixing the color conductive powder ink 5. This process consists of forming 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.
Color conductive powder ink 5 is supplied between 24 and voltage v1 is applied between the conductor 21 and the electrode A24 by the power source A25. By applying the voltage v1, an electrical conduction path is formed in the color conductive powder ink 5 in the gap between the powder ink supply roller 23 and the electrode A24, and the color is in contact with the dielectric layer 22 of the powder ink supply roller 23. Charge Q1 is injected into the conductive powder ink 5. However, the color conductive powder ink 5 in contact with the powder ink supply roller 23
The color conductive powder ink 5 above only becomes an electrically conductive path and no charge is injected into it. As a result, only the color conductive powder ink 5 in contact with the powder ink supply roller 23 is injected with powder ink due to electrostatic force. A thin layer is deposited on the feed roller 23.

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.
A powder ink supply roller 23 that sequentially supplies the color conductive powder ink 5 onto the ink sheet 13 is arranged on the opposite side of the electrode 28, and a voltage v2 is applied between the electrode B26 and the powder ink supply roller 23 by a power source B27. By applying
Color conductive powder ink 5 in contact with ink peeling section 18
is the charge Q=Q1-Q2 determined from voltages v1, v2 and capacitances C1, C2 (C1 is the capacitance in the dielectric layer 22 of the powder ink supply roller 23, and C2 is the capacitance in the insulating support 11). (-Ql represents the electric charge generated on the conductor 21 of the powder ink supply roller 23, and C2 represents the electric charge generated on the electrode B26).

Here, the binding force F1 of the color conductive powder ink 5 to the powder ink supply roller 23 and the adhesion force F2 to the ink peeling section 18 are as follows: F1=kl*Q12/Di2 F2=2*Q22/D22 expressed. (kl and k2 are constants, Dl is the thickness of the dielectric 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 color conductive powder It becomes possible to attach the body ink 5 to the insulating support 11. That is, by appropriately selecting the voltages v1 and v2 and the capacitances C1 and C2, the color conductive powder ink 5 can be attached to the ink peeling section 18. On the other hand, regarding the color conductive powder ink 5 that has come into contact with the ink untransferred area 19, the electric charge Q2 is transferred to the conductive ink untransferred area 19.
Since the color conductive powder ink 5 has the electric charge Q1, the color conductive powder ink 5 is attached to the powder ink supply roller 23. The color conductive powder ink 5 replenished only to the ink peeling part 18 of the ink sheet 13 in this way is fixed onto the insulating support 11 by the heat roller 28 and the support roller 29, and the ink layer 1
2, 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 .

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 thermal transfer printing devices, stylus heads used in electrical thermal transfer printing devices can also be used. A current-carrying layer is formed on the opposite side of the ink layer. As the image forming object 16, thermal transfer paper, plain paper, OHP sheet, etc. are used.

[Example 1] Yellow conductive powder ink Preparation of powder ink inner core Binder resin paraffin wax 50 g Ethylene-vinyl acetate copolymer 0 g Dispersant butyl acrylate-maleic anhydride copolymer 15 g Colorant metal sole Disazo Yellow (Barium Lake) 5g Mix and mix the above using a batch mixer, and mix with a jet mill for 5~
It was pulverized into fine particles of 20 μm to obtain a powder ink inner core.

Preparation of conductive coloring material Coloring material Metalsolet Disazo Yellow (Barium Lake) 16 g Add 1 part of the above to iron chloride
The 0 dispersion was mixed with 200 ml of wt% aqueous solution and dispersed using a colloid mill, and virol was added thereto while stirring while keeping the temperature at 0 to 2°C, and oxidative polymerization was carried out to form the free sulfonic acid groups of metalsolet disazo yellow and virol. A conductive colorant was created by grafting a conductive polymer through a ring complex formation reaction.

The entire amount of the powder ink inner core and conductive coloring material was placed in a ball mill, external addition treatment was performed by mechanochemical reaction, and the unattached conductive coloring material was removed using a classifier to obtain a yellow conductive powder ink.

[Example 21 Magenta conductive powder ink Creating inner core of powder ink Binder resin paraffin wax 50 g Ethylene-vinyl acetate copolymer 0 g Dispersant Butyl acrylate-maleic anhydride copolymer 10 g Polyoxyethylene alkylphenol Ether 10 g Mix and mix the above using a batch mixer, and mix with a jet mill for 5~
It was pulverized into fine particles of 20 μm to obtain a powder ink inner core.

Preparation of conductive colorant Colorant Lake Red 0 8 g Mix the above with 200 ml of 1wt% iron chloride aqueous solution and disperse with a colloid mill. Keep the 0 dispersion at 5°C and stir, then add 3-methylthiophene. Oxidative polymerization was then carried out, and a conductive polymer was grafted through a complex formation reaction between the free sulfonic acid group of Lake Red C and the thiophene ring to create a conductive coloring material.

The entire amount of the powder ink inner core and the conductive coloring material was placed in a ball mill, external addition treatment was performed by mechanochemical reaction, and the unattached conductive coloring material was removed using a classifier to obtain a magenta conductive powder ink.

[Example 3] Creation of inner core of cyan conductive powder ink powder ink Binder resin paraffin wax 50 g Ethylene-vinyl acetate copolymer 0 g Dispersant styrene-maleic anhydride copolymer 0 g Sorbitan alkylate 10 g Mix and knead the above using a batch kneader, and then use a jet mill to mix and knead.
It was pulverized into fine particles of 20 μm to obtain a powder ink inner core.

Preparation of conductive coloring material Coloring material phthalocyanine blue 6 g The above mixture was mixed with ammonium peroxodisulfate/methanol solution, milled using a ball mill, filtered and dried to prepare a polymerization catalyst-treated coloring material.

Next, the mixture was dispersed in an acidic sulfuric acid solution, kept at 0°C, and aniline was added while stirring to perform oxidative polymerization, and a conductive polymer was grafted to create a conductive coloring material.After the reaction, the mixture was filtered and washed to remove sulfuric acid. Excluded.

The entire amount of the powder ink inner core and the conductive coloring material was placed in a ball mill, external addition treatment was performed by mechanochemical reaction, and the unattached conductive coloring material was removed using a classifier to obtain a cyan conductive powder ink.

[Comparative Example Co-Yellow Conductive Powder Ink Powder Ink Preparation of Inner Core Binder Resin Paraffin Wax 50 g Ethylene-Vinyl Acetate Copolymer 5 g Dispersant Butyl Acrylate-Maleic Anhydride Copolymer 15 g Colorant Metal Soret Disazo Yellow (barium lake) 10 g Mix and mix the above using a batch mixer, and mix with a jet mill for 5~
It was pulverized into fine particles of 20 μm to obtain a powder ink inner core.

48 g of indium tin oxide (theoretical coverage rate 200%), which is a conductive fine powder, is added to the total amount of the inner core of the powder ink, placed in a ball mill, subjected to external addition treatment by mechanochemical reaction, and excess indium tin oxide is removed using a classifier. was removed to obtain a yellow conductive powder ink.

Table 1 shows the electrical resistance values of the conductive powder inks prepared in Examples 1.2.3 and Comparative Examples.

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.
6Ω・cm or less, and as a result of using it in the thermal transfer image forming apparatus shown in Figure 3, all color conductive powder inks showed no color turbidity in the ink layer fixed on the insulating support by the heat roller. There was no occurrence, and the printed matter on the image forming body had a clear color. Furthermore, since the resistance value was sufficiently small, selective adhesion to the ink peeled portions on the ink sheet was possible, and the ink sheet could be easily recycled.

On the other hand, the color conductive powder ink of the comparative example, which is a conventional example, has a resistance value on the order of 108 Ω・cm, and although it is possible to selectively adhere to the ink peeling part on the ink sheet, The fixed ink layer became yellowish white and color turbidity occurred. Further, during fixation using a heat roller, indium tin oxide was not sufficiently dispersed in the ink layer, and voids were observed in the printed matter.

[JI! As described above, according to the present invention, the color conductivity used in a thermal transfer image forming apparatus that has a step of forming an image by a thermal transfer printing method and a step of regenerating an ink sheet using electrostatic force. Powder ink has a colored conductive layer formed from a coloring material made conductive by graft polymerizing a conductive polymer on the surface of the powder ink inner core, so the ink layer does not become cloudy and has clear colors. A printed matter was obtained, and a color conductive powder ink usable for a regenerated thermal transfer image forming apparatus was obtained.

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 sectional view of the color 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... Dispersant 3... Powder ink inner core 4... Conductive layer 5... Color conductive 1E powder ink 11... Insulating support 12... Ink layer 13... Ink sheet 14... Ink sheet conveyance direction 15 ・ 16 ・ l 7 ・ 18 ・ 19 ・ 20 ・ 21 ・ 22 ・ 23 ・ 24 ・ 25 ・ 26 ・ 27 ・ 28 ・ 29 ・ 30 ・ 3 l - Thermal head Image forming body Ink transfer part Ink peeling part Ink untransferred part Scanning direction Conductor Conductor Powder Ink supply roller Electrode A Power supply A Electrode B Power supply B Heat roller support roller Cleaning blade Static elimination brush and above

Claims (1)

[Claims] In color conductive powder ink used in a thermal transfer image forming apparatus that has a step of forming an image by a thermal transfer printing method and a step of regenerating an ink sheet using electrostatic force, a highly conductive powder is applied to the surface of the inner core of the powder ink. A color conductive powder ink characterized by having a colored conductive layer formed of a colorant made conductive by graft polymerizing molecules.