JPH02199459A - Powder ink - Google Patents

Abstract

PURPOSE:To obviate the generation of fluctuations in the optical density of images by a heat transfer method by forming a 1st shell essentially consisting of a soft releasable material and a 2nd shell consisting of a conductive material on an internal nuclear particle. CONSTITUTION:The above ink is formed by forming the 1st shell essentially consisting of the soft releasable material (A) and the 2nd shell consisting of the conductive material (B) on the internal nuclear particle contg. a waxy compd. such as paraffin wax, resin, such as ethylene/vinyl acetate copolymer, and the conductive material, such as carbon black. The component A is preferably a material which has 60 to 180 deg.C softening point and is not compatible with the above-mentioned waxy compd., for which polyethylene, etc., are usable. Carbon black, etc., are usable for the component B. The external addition of the components A, B by a mechanochemical reaction, etc., is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to powder ink used in image forming apparatuses.

[Prior Art] As a powder ink used in an image forming method that includes a step of forming an image by a thermal transfer method and a step of recycling an ink sheet, the present inventor has developed a powder ink containing a wax-like compound as a main component. I suggested body ink.

(Japanese Patent Application No. 63-214441) This is a conductive powder ink having a resistance value of 108 Ωcm or less. A conductive ink layer is applied on an insulating ink sheet, and when an image is formed, the underlying ink sheet is exposed at the portion of the ink layer used. While installing an electrode on the back side of the ink sheet and applying a bias voltage,
By bringing the powder ink into contact with the ink layer side, charge is injected into the powder ink and the powder ink adheres only to the portion where the underlying ink sheet is exposed. However, in the conductive ink layer, the charge escapes and the powder ink does not adhere. The powder ink deposited on the ink sheet is melted and fixed onto the ink sheet using a hot roll or the like, and a new ink layer is regenerated.

[Problems to be Solved by the Invention] However, when an ink sheet is recycled using powder ink with this configuration, the powder ink is melted and fixed onto the ink sheet to form an ink layer, and then the paper is When the image is transferred to the ink sheet, the image portion cannot be completely peeled off from the ink sheet, and ink remains on the ink sheet, resulting in a phenomenon in which the homogeneity of the ink layer is not ensured during the regeneration process. That is, when the resistance value of the remaining ink layer portion is large or when a thin amount of conductive ink remains, variations occur in the adhered thickness of the ink layer. When forming an image using this recycled ink sheet, the optical flow rate (hereinafter 0.D
There is a problem in that variations in the values (referred to as , values) occur.

The present invention has been made to solve these problems, and its purpose is to use powder ink for use in an image forming method that includes a step of forming an image by a thermal transfer method and a step of recycling an ink sheet. The object of the present invention is to provide a powder ink that can obtain a homogeneous image without variations in O, D, and D values when the powder ink is fused to an ink sheet and an image is formed.

[Means for Solving the Problems] The powder ink of the present invention is a powder ink composed of a waxy compound, a resin, and a conductive material, in which the powder ink is a material whose main component is a soft release material. [Function] According to the above structure of the present invention, the powder ink acts as a release agent for the ink sheet on the surface of the powder ink. By having an outer shell mainly composed of a soft release material, when an ink layer is formed by melting and fixing onto an ink sheet, when thermally transferred to an image forming material such as paper, the ink layer is completely removed from the ink sheet. The inventor's experiments have shown that the phenomenon of peeling occurs. In addition, by having a surface coating layer of a conductive material near the surface of the powder, it is necessary for powder ink used in an image forming method that includes a step of forming an image by a thermal transfer method and a step of recycling an ink sheet. It had a high resistance value, and was also able to prevent adhesion caused by soft release materials.

[Example code] Hereinafter, the present invention will be explained in detail with reference to Examples.

The waxy compounds used in the powder ink of the present invention include plant-based natural waxes such as candelilla wax, carnauba wax, and rice wax, animal-based natural waxes such as beeswax and lanolin, and mineral-based waxes such as montan wax and osikerite. natural wax, paraffin wax,
Microcrystalline wax, natural petroleum wax such as petrolatum, polyethylene wax, Fischer wax, etc.
Selected from synthetic hydrocarbon waxes such as Tropsch wax, modified waxes such as montan wax derivatives and paraffin wax derivatives, hydrogenated waxes such as hydrogenated castor oil and hydrogenated castor oil derivatives, and synthetic waxes such as fatty acids, acid amides, esters, and ketones. One type of wax or a blend of two or more types can be used.

Furthermore, the resins used in the powder ink of the present invention include acrylic resins such as polyacrylate and polymethacrylate, styrene resins such as polystyrene and poly-1-methylstyrene, butyral resins, polyvinyl chloride,
polyvinylidene chloride, polyvinyl fluoride,
Polyvinylidene fluoride, polyester resin, polycarbonate resin, cellulose resin, polyarylate resin, polyethylene resin, epoxy resin, urethane resin,
Thermosetting resins such as phenol resin, melamine resin, urea resin, silicone resin, alkyd resin, polyvinyl alcohol, polyallyl alcohol, polybenzyl alcohol, poly-2-hydroxyethyl methacrylate, polyvinylpyrrolidone, polyvinylpyridine, polyvinylamine, Single or combination resins selected from among resins such as polyallylamine, polyvinyl acrylic acid, polyvinyl methacrylic acid, polyvinyl sulfate, polylactic acid, casein, hydroxypropylcellulose, starch, gum arabic, polyglutamic acid, polyaspartic acid, and nylon resin. It is a polymer or a mixture. The resin may be a substance that is incompatible with the wax-like compound, but it is preferable that the resin be a substance that is compatible with the waxy compound.

As the conductive material used in the present invention, carbon black,
Any of various metal powders and metal complex salts can be used.

In addition, as the soft mold release material used in the first outer shell of the present invention, olefin resins such as polyethylene and propylene, and waxes such as Hoechst wax, ester wax, polyethylene wax, hydrogenated castor oil, and derivatives thereof. is used, and its softening point is 60~
180°C is desirable.

As the conductive material used in the second outer shell of the present invention, carbon black can be used, and carbon black is preferably used as a conductive material with a resistance value of 10 8 Ωcm or less.

In addition to the above-mentioned substances, the powder ink of the present invention may contain additives to the extent that its fluidity, conductivity, fixability, etc. are not impaired. As additives, 5i02, T i 02
, hydrophobic silica, fluidity improvers such as carbon black,
Metal soap, dispersant such as polyethylene glycol, F e
304, Fe2O3, Fe, Cr, Ni,
Magnetic powders such as Co and ferrite are used alone or in combination.

As a method for manufacturing the powder ink of the present invention, a method known as a normal method for manufacturing toner can be applied. - To give an example, powder ink is produced by melting, kneading, pulverizing, and classifying, and then a resin is added to the outer shell, and the powder ink is dispersed in a solution that dissolves the resin but not the powder ink. After dissolving the resin for the outer shell, a powder ink having the resin in the outer shell can be produced by spray drying.

Further, the particle size of the powder ink of the present invention is preferably determined by the amount of powder ink that adheres to the peeled part of the ink layer when recycling the ink sheet and the thickness of the ink layer. In other words, the powder ink that adheres to the peeled part of the ink layer is filled below the powder ink layer due to the above-mentioned reason, and based on the filling rate of this powder ink and the thickness of the ink layer after regeneration, the powder ink adheres to the peeled part of the ink layer. The optimum value of the ink particle size can be predicted. For example, the thickness of the ink layer after regeneration is 3.5 μm, and the filling rate of powder ink is 90 μm.
%, the average particle size of powder ink is 9.5 to 10
．． The thickness is preferably 5 μm.

FIG. 1 schematically shows an image forming method including a step of forming an image by a thermal transfer method using the powder ink of the present invention and a step of recycling an ink sheet.

Ink sheet 1 having an ink layer 3 on an insulating support 2
moves in the direction of the arrow 4, and by the thermal head 5,
The ink is transferred to the recording medium 7 moving in the direction of arrow 6,
An image is formed on the recording medium 7 (step of forming an image using a thermal transfer method).

By forming the image, a peeling part 8 of the ink layer and an adhesion part 9 of the ink layer are formed on the ink sheet 1.

The electrode 1 is placed in contact with the insulating support 2 of the ink sheet 1.
A conductive roller 12 that sequentially supplies powder ink 11 onto the ink sheet 1 is placed on the opposite side of the electrode 10 with the ink sheet 1 in between. Powder ink 11 is supplied onto ink sheet 1 while a bias voltage (hereinafter referred to as Vb) is applied between electrode 10 and conductive roller 12 by power source 13 . The powder ink 11 that has come into contact with the peeled part 8 of the ink layer of the ink sheet is charged with an amount proportional to the product of the capacitance of the insulating support 2 and vb because the peeled part 8 of the ink layer exhibits insulation. The injected material adheres to the insulating support 2 by electrostatic force. However, the ink layer adhering portion 9 of the ink sheet 1 and the insulating support 2
Since the ink layer and the powder ink are conductive, the powder ink 11 that has come into contact with the powder ink that has adhered to the surface merely serves as a path for electric charge and does not have any adhesive force. In this way, powder ink can be replenished only to the peeled portion of the ink layer of the ink sheet. The ink sheet 1 supplemented with powder ink is fixed onto the ink sheet by the powder ink fixing means 14. Through the above steps, the ink sheet is recycled.

Here, a polymer film such as polyethylene terephthalate, polyphenylene sulfide, polyimide, polyamide, etc. can be used as the insulating support of the ink sheet, and as the thermal head 5, in addition to the head used in the fusion heat transfer method, electric heat transfer A stylus head used in this method can also be used, and in the case of an electrically conductive thermal transfer method, the structure of the ink sheet is such that an electrically conductive layer or the like is formed on the opposite side of the ink layer across the ink sheet. As the recording medium 7, plain paper, OHP sheet, etc. are used. Further, as the conductive roller 12 for conveying the powder ink and the powder ink fixing means 14, methods such as a magnetic brush development method and a contact development method, which are known in electrophotography, can be applied, and methods such as a heat roll fixing method, Methods such as a flash fixing method and a pressure fixing method can be applied.

[Example 1] Paraffin wax 34 wt% carnauba wax 30 wt% ethylene/vinyl acetate copolymer 30 wt% carbon black as inner core particles
6 wt% and kneaded to obtain an average particle size of 9
．． Particles of 7 μm were produced. Further, as a first outer shell, 8 parts by weight of polyethylene wax with a particle size of 0.5 μm is externally added to 100 parts by weight of the inner core particles through a mechanochemical reaction using a fine micron mechanofusion, and further, Similarly, 1.5 parts by weight of carbon black was added externally by mechanochemical reaction to prepare powder ink A1. The volume resistivity was 103 Ωcm. In addition, the loss modulus when applying a 3 Hz shear strain using a flat plate viscometer is 3 x 103 d yn / at 180°C.
cm2.

Since the resistance value of powder ink A1 was the predetermined resistance value,
Image formation and ink sheet recycling were actually performed by the method shown in Figure 1. A polyethylene terephthalate film having a thickness of 4 μm was used as the insulating support of the ink sheet, and the ink layer was formed to have a thickness of 4 μm from a composition consisting of almost the same components as the powder ink A1. vb 70
Set to V to adhere powder ink to the ink layer, 12
By heating to 0C and applying pressure, the powder ink spread on the ink sheet and the ink layer was regenerated.

After printing a continuous pattern of 4×4 dots, no ink remained on the ink sheet in the ink-used areas. Thereafter, an image was formed, and the produced image-formed product had good reproducibility <O, D, value 1. even after the 1000th playback.
6 images were formed.

[Comparative Example 1] Paraffin wax as inner core particles 34 wt% carnauba wax 30 wt% ethylene/vinyl acetate copolymer 30 wt% carbon black
6 wt% and kneaded to produce particles with an average particle size of 9.7 μm. Further, 1.5 parts by weight of carbon black was externally added to 100 parts by weight of the inner core particles to prepare powder ink B1.

Powder ink B1 has a shear rate of 1 when given a shear rate of 3Hz.
When the loss modulus at 80°C is measured with a plate viscometer, it is 3
It was 103 dyn/cm2. Also, the volume resistivity is 1
It was 08Ωm.

A polyethylene terephthalate film with a thickness of 4 μm was used as the insulating support of the ink sheet, and the ink layer was formed with a composition consisting of almost the same components as powder ink B1 to a thickness of 4 μm. The powder ink was applied to the ink layer by setting vb to 70 V, heated to 120° C., and pressure was applied to sufficiently curl the powder ink onto the ink sheet and regenerate the ink layer. After printing a continuous pattern of 4×4 dots, 5 to 10% of ink remained in the ink-used areas on the ink sheet. The image formed by forming the image was 0°D at the 1000th reproduction, and the image had a variation in value from 1.6 to 0.8. As described above, a clear difference in the releasability from the ink sheet was observed due to the presence of the first shell made of a substance whose main component is a releasable substance on the surface.

[Example 2] Paraffin wax 34 wt% carnauba wax 30 wt% ethylene/vinyl acetate copolymer 30 wt% carbon black as inner core particles
6 wt% and kneaded to obtain an average particle size of 1
Particles of 0.3 μm were produced. 100 parts by weight of inner core particles,
14 parts by weight of polyethylene and 1.5 parts by weight of carbon black are dispersed in 1000 parts by weight of toluene,
After spray drying, it is classified to have an average particle size of 10゜5μm.
A surface-coated powder ink was prepared.

At this time, the softening point of the polyethylene used is 55 to 18
Powder inks B1 to B5 were produced by changing the temperature up to 5°C.

Powder inks B1 to B5 have a loss modulus of 1.6xlO when measured with a flat plate viscometer when a sliding speed of 3Hz is applied.
"dyn/cm2 (180°C). Also, the volume resistivity was 104Ω mark.

A polyethylene terephthalate film with a thickness of 4 μm was used as an insulating support of the ink sheet, and the ink layer was formed with a composition consisting of almost the same components as powder ink A2 to a thickness of 4 μm. The powder ink was applied to the ink layer by setting vb to 70 V, and by heating to 180° C. and applying pressure, the powder ink spread on the ink sheet and the ink layer was regenerated. After printing a continuous pattern of 4 x 4 dots, there is no visible ink left on the ink-used areas on the ink sheet. After that, an image is formed, and the produced image-formed object is ○ even if it is played for the 1000th time.
, D, an image with a value of 1.6 could be formed. However, the image quality and blocking resistance changed depending on the softening point of the externally added substance. The results are shown in Table 1.

As shown in Table 1 and above, good image quality was obtained at temperatures below 180°C. Further, at 606C or higher, toner blocking was prevented.

[Example 3] Paraffin wax 34wt%-16 = Carnauba wax 30wt% ethylene.
30 wt% of vinyl acetate copolymer and 6 wt% of carbon black were mixed and kneaded to prepare inner core particles having an average particle size of 9.7 μm. Further, as a first outer shell, polypropylene having a particle size of 0.2 μm was externally added to the inner core particles by mechanochemical reaction using a fine micron mechanofusion. At this time, the amount of polypropylene added was adjusted, and the coated film thickness was adjusted as shown in Table 2.

Table 2 Furthermore, 1.5 parts by weight of carbon black was added externally by the same mechanochemical reaction.

Powder inks C1 to C5 have a loss modulus of 1.6xlO when measured with a flat plate viscometer when a shear rate of 3Hz is applied.
"dyn/cm2 (180°C).The volume resistivity of each is shown in Table 3 below.

A polyethylene terephthalate film with a thickness of 4 μm was used as the insulating support, and the ink layer was formed with a composition consisting of almost the same components as the powder ink used to have a thickness of 4 μm. The powder ink was applied to the ink layer by setting vb to 70 V, and by heating to 180° C. and applying pressure, the powder ink spread on the ink sheet and the ink layer was regenerated. After printing a continuous pattern of 4 x 4 dots, remove the remaining ink from the ink-used areas on the ink sheet using the following method.
Shown in the table.

From the table, when the thickness of the first outer shell layer was 0.01 μm or more, disturbances in image quality caused by uneven peeling of the ink layer were prevented. In addition, the thickness of the outer shell layer is 2 μm.
If it is below, an increase in resistance value can be prevented.

Table 3 [Example 4] Paraffin wax carnauba wax ethylene/vinyl acetate copolymer carbon black 34 wt % 30 wt % 30 wt % 6 wt % were mixed, kneaded, crushed and classified to obtain inner core particles with an average particle size of 9.7 μm. Created. Furthermore, as the first outer shell, 10
0 parts by weight of the inner core particles and 6 parts by weight of the average particle size of 0. 2μm
of polypropylene was externally added by mechanochemical reaction using a micron mechanofusion.

Further, powder inks D1 to D5 were prepared by pouring carbon black in amounts shown in Table 4 below.

Ta. Table 4 shows the loss modulus measured using a plate viscometer and the volume resistivity of powder inks D1 to D5 at 180° C. when a rubbing speed of 3 Hz was applied.

A polyethylene terephthalate film with a thickness of 4 μm was used as the insulating support, and the ink layer was formed with a composition consisting of almost the same components as the powder ink used to have a thickness of 4 μm. At this time, D5 had too high a viscosity and was difficult to form into an ink sheet. Vb is set to 70V to adhere powder ink to the ink layer, and by heating to 180℃ and applying pressure, the powder ink spreads on the ink sheet.
The ink layer has been regenerated.

Table 4 Ink agglomeration occurred and image quality deteriorated.

In addition, the amount of carbon black in the outer shell layer was reduced to 20 wt%.
Unless the conditions are as follows, the fluidity of the powder ink during melting will decrease, resulting in a decrease in ink layer formation and image quality.

Table 5 Table 5 below shows the ink remaining in the ink-used areas on the ink sheet after printing a continuous pattern of 4×4 dots and the image quality when an image is formed. As mentioned above, the amount of carbon black for the second outer shell layer was set to 0.1 wt%.
Although the above embodiments have been described in detail, the present invention is not limited to these embodiments, and the present invention can be realized by adopting the configuration described above. It will be obvious from

[Effect of the invention] As described above, according to the present invention, a waxy compound,
In powder ink made of resin and conductive material, the powder ink has an outer shell mainly composed of a soft release material, which makes it difficult for the powder ink to peel off from the ink sheet when it is fixed on the ink sheet. It has become possible to provide a powder ink that is optimal for image forming methods that use recycled ink sheets. In addition, if an image is formed using a thermal transfer method using an ink sheet recycled with this powder ink, a high-quality image can be obtained, and the ink sheet can be used repeatedly, significantly reducing running costs. Ta.

The powder ink of the present invention can be used in devices other than devices such as printers, copiers, facsimile machines, etc. that use an image forming method that includes a step of forming an image by a thermal transfer method and a step of recycling an ink sheet. But it can be widely applied. For example, it can be applied to devices such as printers, copiers, and facsimile machines that use electrophotography.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an image forming method using the powder ink of the present invention, which includes a step of forming an image by a thermal transfer method and a step of recycling and using an ink sheet. Applicant: Seiko Epson Corporation

Claims (2)

[Claims] (1) In a powder ink composed of a waxy compound, a resin, and a conductive material, the powder ink has a first outer shell made of a substance whose main component is a soft release material, and a second shell made of a conductive material. Powder ink characterized by having an outer shell of (2) In the powder ink according to claim 1, the soft releasing substance has a softening point of 60 to 180°C, is a substance that is incompatible with the waxy compound that is the main component, and is a substance that is incompatible with the waxy compound that is the main component. A powder ink characterized in that the outer shell has a thickness of 0.01 to 2 μm.