JPH04146187A - Production of powder ink - Google Patents

Abstract

PURPOSE:To suppress aggregation of powder ink and to suppress fluctuation of the density of a print by dispersing inner shells, comprising binder component and coloring material, into a resin particle dispersion liquid thereby adhering the resin particles onto the surface of the inner shell of the powder ink and then dissolving thus adhered resin particles and forming a resin coating layer thereafter making them conductive. CONSTITUTION:Binder component and coloring material are admixed and kneaded by means of a buch type kneading machine and then the admixture is ground through a jet mill into micro particles thus preparing powder ink inner shells 1. The powder ink inner shells are then admixed with resin particles 2 and subjected to adhesion treatment through wet milling method followed by drying through a spray dryer thus producing a toner 6 adhered with resin particles. The powder ink adhered with resin particles is then sprayed with acetone mist 3 through a two-fluid nozzle when the powder ink is delivered through a powder supply nozzle thus dissolving the resin particles. It is then subjected to bonding treatment 7 to produce a powder ink coated with resin 8. The powder ink coated with resin is then added with acetylene black and subjected to conduction treatment 9 through mechanochemical reaction thus producing a powder ink 10.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to the production of powder ink used in image forming apparatuses that adhere colored fine powder onto a dielectric material using electrostatic force and then perform printing using a thermal transfer method. Regarding the method. Specifically, the present invention relates to a method for producing powder ink for use in a thermal transfer image forming apparatus, a so-called recycled thermal transfer image forming apparatus, which includes a step of forming an image by a thermal transfer printing method and a step of recycling an ink sheet using electrostatic force.

[Conventional technology] Conventionally, colored fine powder is attached to a dielectric material by electrostatic force,
Furthermore, powder ink, so-called toner, and its manufacturing method used in image forming apparatuses that print by thermal transfer method are as follows: U.S. Patent No. 3,639,245 for conductive toner, and U.S. Pat.
etc. are proposed.

Further, Japanese Patent Application No. 1-295876 has been proposed as a recycled thermal transfer image forming apparatus and a method for recycling an ink sheet.

[Problems to be Solved by the Invention] Regarding the powder ink used in the regenerated thermal transfer image forming apparatus proposed in Japanese Patent Application No. 1-295876, the conductive ink shown in the conventional example US Pat. No. 3,639,245 has been solved. When a plastic toner is used, it is possible to regenerate the ink sheet using electrostatic force, but the high melting temperature of the thermoplastic resin, which is the main component of the toner, makes it difficult to transfer the ink onto the image forming object. Difficult to use. In contrast, the conductive wax-based toner disclosed in US Pat. No. 3,925,219 allows image formation by thermal transfer printing methods and regeneration of ink sheets using electrostatic forces. However, when the above toner is used as a powder ink, due to the adhesive strength of the wax component exposed on the toner surface near room temperature, the shelf life may deteriorate due to agglomeration of the powder ink, and the powder may become powdery when the ink sheet is recycled. The body ink sticks to the ink layer on the ink sheet, and each time the ink sheet is recycled, the thickness of the ink layer in the non-printing area increases, and when printing, the uneven thickness of the ink layer causes temperature unevenness in the printed matter. It became clear that the problem was occurring.

Therefore, the present invention is intended to solve these problems, and its purpose is to reduce the aggregation of powder ink to improve storage stability, and to prevent temperature unevenness of printed matter produced by recycled thermal transfer image forming equipment. The present invention provides a method for producing powder ink.

[Means for Solving the Problems] The method for producing powder ink of the present invention is 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 recycling an ink sheet using electrostatic force. A method for producing a powder ink includes the steps of creating a powder ink inner core from a binding component and a coloring material, and dispersing the powder ink inner core in a resin particle dispersion to adhere resin particles to the surface of the powder ink inner core. The present invention is characterized by comprising a step of dissolving the adhered resin particles and fixing the powder ink inner core and adjacent resin particles to form a resin coating layer, and a step of making the powder ink electrically conductive.

[Operations] The powder ink used in the regenerated thermal transfer image forming apparatus is produced by creating an inner core of the powder ink from a binding component and a coloring material, and then applying a conductivity imparting agent to the outside. When a low melting point wax or the like is used as a binding component, the powder ink aggregates due to the tackiness of the wax exposed on the surface. However, if the resin particles in the resin particle dispersion are attached to the inner core of the powder ink, the resin particles are dissolved to form a resin coating layer on the surface of the inner core of the powder ink, and then the conductivity imparting agent is externally added. , the wax is not exposed on the surface of the powder ink, making it possible to eliminate aggregation of the powder ink.

In addition, if resin particles with a specified particle size are uniformly adhered to the surface of the powder ink inner core and the resin particles are dissolved to form a resin coating layer on the powder ink inner core surface, the particle size of the resin particles used can be A film with a film thickness that depends on the film thickness is formed, making it possible to create a film with a specified film thickness with good reproducibility.

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

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

The powder ink inner core 1 consists of a binding component and a coloring agent, and the binding component includes vegetable waxes such as candelilla wax and carnauba wax, animal waxes such as beeswax and lanolin, and mineral waxes such as montan wax. Petroleum waxes such as paraffin wax and microcrystalline wax, synthetic hydrocarbon waxes such as polyethylene wax and Fischer-Trobs wax, modified waxes such as montan wax derivatives and paraffin wax derivatives, hydrogenated waxes such as hydrogenated castor oil and hydrogenated castor oil derivatives. , waxes such as synthetic waxes such as fatty acids, acid amides, esters, and ketones, polyacrylate derivatives, polymethacrylate conductors, polystyrene derivatives, butyral resins, polyester resins, cellulose resins, polyethylene resins, polypropylene resins, vinyl acetate resins, and Thermoplastic resins of these copolymers are used, and these may be used alone or in combination.

The colorants are Benzidine Yellow Disazo Yellow for yellow, Carmen 6B and Lake Red C for red.
, pigment scarlet, quinacridone, phthalocyanine blue ink quinacridone for blue colors, and carbon blacks such as furnace black, lamp black, acetylene black, and channel black for black colors are used.

The binding component and colorant are mixed and kneaded using a continuous screw extruder, a batch type Banbury mixer, etc., a wet mixing method such as a homogenizer, colloid mill, ball mill, etc., and a jet mill, cutter mill, ong mill, etc. The ink is ground into fine powder with a particle size of 5 to 20 μm using a ball mill or the like to create a powder ink inner core 1. It is also possible to create the powder ink inner core by a wet method such as a suspension polymerization method.

The powder ink inner core 1 is made of ferrite, magnetite,
Magnetic powder made of magnetic materials such as iron, chromium, and nickel is added. In addition, in order to disperse colorants and magnetic powder in binding components, anionic surfactants, cationic surfactants, nonionic surfactants, polyacrylate derivatives, polymethacrylate derivatives, anhydrous It is also possible to add a dispersant such as a polycarboxylic acid salt such as a maleic acid copolymer or a trussperse superdispersant.

Resin particles 2 can be produced by emulsion polymerization method, emulsion polymerization method without emulsifier added,
Polyacrylate derivatives, polymethacrylate derivatives, polystyrene derivatives, polyethylene, polypropylene, polyvinyl acetate, and copolymers thereof, or polyester resins, cellulose resins, butyral, created by seed polymerization, dispersion polymerization, suspension polymerization, etc. Spray-dried fine particles of resin or the like are used. The particle size of the resin particles is 0. The particle size is adjusted to an arbitrary particle size of 1 μm to 3 μm, and adjusted according to the thickness of the resin coating layer. Furthermore, the resin particles 2 are dispersed in a solvent 4 to prepare a dispersion liquid. As the dispersion solvent, petroleum solvents such as hexane, heptane, isoperkerosene, etc., and water are used. If the dispersibility of resin particles is poor, use anionic surfactants, cationic surfactants, nonionic surfactants, polyacrylate derivatives, polymethacrylate derivatives, maleic anhydride copolymer as the solvent. Polycarboxylic acid salts such as coalescence,
It is also possible to add a surfactant such as a trussperse superdispersant. In addition, resin particles produced by polymerization method are
It is also possible to use the resin particle dispersion after polymerization as a dispersion by removing excess emulsifiers, stabilizers, polymerization initiators, etc. by dialysis or the like.

The solvent 3 is used to dissolve and fix the resin particles 2, and includes halogenated hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, dichloroethane, and chlorobenzene;
Alcohols such as methanol, methylcellosolve, benzyl alcohol, ethers such as dioxane, tetrahydrofuran, pencil ether, esters such as ethyl acetate, butyl acetate, ketones such as furfural, acetone, methyl ethyl ketone, cyclohexanone, benzene, toluene , aromatics such as xylene, and nitrogen compounds such as nitrobenzene, acetonitrile, diethylamine, aniline, dimethylformamide, and pyrrolidone.

The powder ink inner core 1 and the dispersion of the resin particles 2 are mixed and subjected to an adhesion treatment 5 to obtain a resin particle adhering powder ink 6. At this time, the powder ink inner core 1 can be used either as a powder or in the form of a dispersion dispersed in a solvent.

Adhesion treatment 5 includes the Betero agglomeration method that utilizes electrostatic adhesion due to the zeta potential difference between the surface of the inner core of the powder ink and the surface of the resin particle, the wet milling method that involves milling a mixed dispersion using a ball mill, etc., and the inner core of the powder ink that is cupped. Applicable methods include a coupling agent method in which the material is treated with a ring agent and then mixed with resin particles for adhesion treatment, and an interfacial precipitation method in a resin solution resin particle dispersion system. In Peter flocculation method, powder ink inner core 1/
The particle size ratio of the resin particles 2 is preferably 3 or more, and the composition is preferably adjusted so that the zeta potentials of the powder ink inner core 1 and the resin particles 2 have opposite polarities. In the wet milling method, the particle size ratio of powder ink inner core 1/resin particle 2 is preferably 5 or more.In the coupling agent method, the powder ink inner core 1/resin particle 2 ratio is preferably 5 or more.
/ The particle size ratio of the resin particles 2 is preferably 3 or more, and the powder ink inner core 1 contains silane, titanium, chromium, aluminum, organic phosphorus,
It is necessary to add a coupling agent such as silyl peroxide or to perform surface treatment, and to adjust the composition so that the resin particles have a functional group that can react with the functional group of the coupling agent. In the interfacial precipitation method, resin particles are dispersed in a solution of a resin whose solubility is different from that of the resin particles, the powder ink inner core 1 is dispersed, and a solvent in which the resin is insoluble is added. Resin particles 2 are attached to the surface of the ink inner core 1.

The resin particle adhering powder ink 6 is coated with the resin particles 2 by the solvent 3.
A resin-coated powder ink 8 is obtained by dissolving and fixing treatment 7. In the case of a resin particle/solvent system in which the dissolution rate is slow, the fixing treatment using a solvent is performed by dispersing the resin particle-attached powder ink 6 in the solvent 3 and performing filtration drying or spray drying. In systems where the dissolution rate is fast, the resin particle-attached powder ink 6 may be treated with solvent vapor, solvent mist treatment, or a mixed solvent of a solvent 3 that dissolves the resin particles 2 and a solvent that does not dissolve the resin particles 2 and has a lower boiling point than the solvent 3. A spray drying method or the like is used. As a fixation method other than dissolution with the solvent 3, emulsifier dissolution coating can be used, and the resin particles 2 are fixed using the low-temperature film forming phenomenon of latex produced by a polymerization method.

The resin-coated powder ink 8 has been subjected to conductive treatment 9 using conductive carbon black such as Ketchien black, acetylene black, and virol black, and conductive metal chalcogenide such as indium-tin oxide and tin oxide-antimony. Ink 10 is obtained [Example 1] Binder component Mic, locrystalline wax 0 g Ethylene-vinyl acetate copolymer 7 g Colorant channel black 3 g The above was mixed and kneaded using a batch kneader, and the above was mixed and kneaded using a jet mill. A powder ink inner core was prepared by pulverizing it into fine particles of ~15 μm.

The entire inner core of the powder ink was mixed with 00 ml of resin particles of methyl methacrylate-n-butyl methacrylate copolymer (1:9) (particle size 0.3 μm, 5% dispersion aqueous solution), and the adhesion treatment was performed by wet milling in a ball mill. This was followed by drying with a spray dryer to obtain a toner with resin particles attached.

While discharging the resin particle-attached powder ink from a powder supply nozzle, acetone 10100O as a solvent was sprayed in a mist form from a two-fluid nozzle to dissolve and fix the ink, thereby producing a resin-coated powder ink.

Add 20 g of acetylene black to the total amount of resin-coated powder ink inner core,
A conductive treatment was performed by a mechanochemical reaction using an ong mill, and excess acetylene black was removed by classification to prepare a powder ink.

This is referred to as "powder ink 1".

[Example 2] Binder component microcrystalline wax Ethylene-vinyl acetate copolymer Colorant channel black 3 g Coupling agent Amine-based silane coupling agent g A powder ink inner core was prepared by pulverizing it into fine particles of 15 μm.

The entire amount of the inner core of the powder ink was mixed with 00 ml of resin particles of methyl methacrylate-n-butyl methacrylate copolymer (1:9) (particle size 0.3 μm, 5% dispersion aqueous solution), and mixed and stirred at 60°C for 10 hours. Adhesion treatment was carried out using a tumbling reaction, followed by drying with a spray dryer to obtain a powder ink with resin particles attached.

A resin-coated powder ink was prepared by spraying acetone 10100O as a solvent in a mist form from a two-fluid nozzle while discharging the resin particle-attached toner from a powder co-feeding nozzle to dissolve and fix the toner.

Add 20 g of acetylene black to the total amount of resin-coated powder ink inner core,
A conductive treatment was performed by a mechanochemical reaction using an ong mill, and excess acetylene black was removed by classification to prepare a powder ink.

This will be referred to as "powder ink 2".

Example 3] Binder component microcrystalline wax 0 g Ethylene-vinyl acetate copolymer 2 g Methyl methacrylate-dimethylaminoethyl methacrylate copolymer g Colorant channel black 3 g The above was mixed and kneaded using a batch kneader, A powder ink inner core was prepared by pulverizing it into fine particles of 10 to 15 μm using a jet mill.

The entire amount of the inner core of the powder ink was mixed with L of resin particles of methyl methacrylate-n-butyl methacrylate-methacrylic acid copolymer (1:8:1) (particle size 0.3 μm, 2% dispersion aqueous solution), and mixed and stirred for 24 hours. Adhesion treatment was carried out by a heterocoagulation method, followed by simultaneous drying and emulsifier-dissolving film formation using a spray dryer to produce a resin-coated powder ink.

Add 20 g of acetylene black to the total amount of resin-coated powder ink inner core,
A conductive treatment was performed by a mechanochemical reaction using an ong mill, and excess acetylene black was removed by classification to prepare a powder ink.

This is referred to as "powder ink 3".

[Example 4] Binder component microcrystalline wax 0 g Ethylene-vinyl acetate copolymer 7 g Colorant channel black 3 g The above was mixed and cross-mixed using a batch kneader, and pulverized into fine particles of 10 to 15 μm using a jet mill. A powder ink inner core was prepared.

The entire inner core of the powder ink was mixed with 00 ml of a resin particle-dispersed ethanol solution consisting of resin particles methyl methacrylate-n-butyl methacrylate copolymer (1:9) (particle size 0.3 μm, 5% dispersion) and polyvinyl butyral (5% dispersion). 750 ml of methanol was added and mixed over 5 hours while stirring with a mechanical stirrer to perform adhesion treatment by interfacial precipitation method, and then dried with a spray dryer to obtain a toner with resin particles attached.

While discharging the resin particle-attached powder ink from a powder supply nozzle, acetone 10100O as a solvent was sprayed in a mist form from a two-fluid nozzle to dissolve and fix the ink, thereby producing a resin-coated powder ink.

Add 20 g of acetylene black to the total amount of resin-coated powder ink inner core,
A conductive treatment was performed by a mechanochemical reaction using an ong mill, and excess acetylene black was removed by classification to prepare a powder ink.

This will be referred to as "powder ink 4".

[Comparative example] Binder component Microcrystaone wax 0 g Ethylene-vinyl acetate copolymer 7 g Colorant channel black 3 g The above was mixed and kneaded using a batch kneader, and pulverized into fine particles of 10 to 15 μm using a jet mill. A powder ink inner core was prepared.

Add 20 g of acetylene black to the remaining core amount in the powder ink,
A conductive treatment was performed by a mechanochemical reaction using an ong mill, and excess acetylene black was removed by classification to prepare a powder ink.

This is referred to as "powder ink 5".

The cross sections of the powder inks of Examples 1 to 4 were observed with a transmission electron microscope, and the average thickness of the resin coating layer was determined to be 0.17, 0.15.0°, 15, and 0.19 μm, respectively. A uniform resin coating layer was formed all around the ink.

Regarding the powder ink of Examples 1 to 4 and Comparative Example 5
Table 1 shows the results of measuring the changes in the angle of repose after being left for 30 days in an environment of 0° C. and 60 RH% and examining the environmental preservation properties.

As shown in Table 1, the powder inks of the examples of the present invention show less increase in the angle of repose when left in a high temperature, high humidity environment, and have improved environmental storage stability, compared to the comparative examples. In powder ink 4 as a comparative example, the powder ink aggregated after being left for 30 days, and the angle of repose could not be measured.

In addition, the change in the optical density of the ink sheet when the powder ink of the present invention is used in a recycled thermal transfer image forming apparatus and only the ink sheet recycling process is performed without performing image formation is shown in the second graph.
Shown in the table.

Table 2 As shown in Table 2, the powder ink of the present invention does not change the optical density of the ink sheet even after being recycled many times, and no excess powder ink adheres to the ink sheet. The density of the printed matter in which images were formed using the powder ink of the example did not change regardless of the number of times of reproduction, and no density unevenness was observed in the printed matter. On the other hand, in the conventional example, the optical density of the ink sheet is increased by recycling the ink sheet. Originally, if only the ink sheet recycling process was performed without performing image formation, the powder ink would not adhere to the ink sheet because there was no ink stripping M part, and the optical density would change like the powder ink in the example. I shouldn't do it, but
In the comparative example, the powder ink adhered to the ink layer on the ink sheet, and the optical density gradually increased.

[Effects of the Invention] As described above, according to the present invention, a powder used in a thermal transfer image forming apparatus having a step of forming an image by a thermal transfer printing cylinder method and a step of recycling an ink sheet using electrostatic force is provided. In the ink manufacturing method, a step of creating a powder ink inner core from a binding component and a coloring material, a step of dispersing the powder ink inner core in a resin particle dispersion liquid and attaching resin particles to the surface of the powder ink inner core, By dissolving the adhered resin particles and fixing the powder ink inner core and adjacent resin particles to form a resin coating layer, and the step of making the powder ink conductive, the surface of the powder ink inner core is It is now possible to form a resin coating layer with a uniform and constant thickness, and as a result, the precipitation of binding components on the surface of the powder ink is prevented, improving environmental stability. Since there was no adhesive adhesion of the powder ink, the temperature of the printed matter did not change regardless of the number of times it was played, and a printed matter with no temperature unevenness 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, and a facsimile machine. It can be applied to a wide range of other things.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a flowchart of the method for producing powder ink of the present invention. 1...Powder ink inner core 2...Resin particles 3...Solvent 4...Solvent dispersion 5...Adhering treatment 6...Resin particle adhesion powder ink 7...Fixing treatment 8...・Resin coated powder ink 9... Conductive treatment 10... Powder ink and above Applicant: Seiko Epson Corporation

Claims (1)

[Claims] In a method for producing powder ink used in a thermal transfer image forming apparatus, the method 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 process of creating a powder ink inner core from a binding component and a coloring material, a process of dispersing the powder ink inner core in a resin particle dispersion liquid and attaching resin particles to the surface of the powder ink inner core, and dissolving the attached resin particles. 1. A method for producing powder ink, comprising the steps of: fixing the powder ink inner core and adjacent resin particles to each other to form a resin coating layer; and making the powder ink conductive.