JPH0452171A - Ink powder - Google Patents

Abstract

PURPOSE:To make the surface of ink layer formed homogeneously by a method wherein binding agent to be used is made to contain 20-100 per cent of polar wax by weight; the polar was shall be such that has penetration of 5 or below, melting point at 60-120 deg.C, and 10-10<5>cP of melt viscosity at 100 deg.C. CONSTITUTION:As binding agent for W various kinds of waxy compound and resin are used. The waxy compound shall be such that is made by blending one, two or more kinds of materials that are selected out of carnauba wax, paraffin wax or the like. The resin shall be such that is made of resins selected out of polyacrylate, nylon resin or the like in the form of simple substance, copolymer or mixed polymer. Furthermore, a polar wax having penetration of 5 or below, melting point at 60-120 deg.C, and 10-10<5>cP melt viscosity at 100 deg.C is added in 20-100 percent by weight. The polar wax is selected out of alpha olefin, maleic anhydride or the like in the form of simple substance or blended substance. Carbon black, Fe3O4 or the like are used as additives. Well-known method for producing of ordinary toner can be applied to production of the title powdered ink.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a powder ink used in an image forming method comprising a step of forming an image by a thermal transfer method and a step of recycling an ink sheet.

[Prior Art] Although there is no conventional example of powder ink used in the above image forming method, among electrophotographic toners, toners containing a wax-based compound as a main component (hereinafter referred to as wax-based toner), e.g. USP-3925219), conductive toner (for example, U5P-3639245), or capsule toner (for example, Japanese Patent Publication No. 49-1588) can be applied. Furthermore, as related technology, the present inventors have
A method for recycling ink sheets disclosed in Japanese Patent Application Laid-Open No. 1-209179 was proposed.

[Problems to be Solved by the Invention] However, these toners cannot be used directly in the process of the present invention, because they are conductive and do not peel off during the process when fixed to the ink sheet by heating. It is necessary to have a low viscosity component. For this reason, the powder ink preferably has a structure in which a conductive agent is added to a wax-based toner. In the powder ink proposed here, when heat is applied to the ink to fix it to the sheet, wax microcrystals are generated on the surface of the ink at a certain rate, changing the conductive ink surface layer to an insulating one. The sheet regeneration process tends to stop working properly, that is, the following phenomenon occurs. On an insulating ink sheet,
Conductive ink is deposited to form an ink sheet, but when this ink is lost during the thermal transfer process,
Only that part is insulating. Therefore, when charge injection development is performed on conductive powder ink, the charge of the powder ink escapes and does not adhere to the conductive ink area, whereas the powder ink adheres to the insulating film area. However, only the portion where the ink is used is selectively regenerated. However, since the surface of the ink in which microcrystals have been generated is insulating, new powder ink is allowed to develop, causing the ink layer to become partially uneven in thickness.

Along with this, the image quality of the image formed by the thermal transfer process using this ink sheet deteriorates.

In addition, WAX, which is the main component of the binder, is usually soft and
When the powder ink is strongly rubbed onto the ink, the powder ink adheres to the ink layer due to adhesive force, causing local thickness unevenness in the ink layer and deteriorating the image quality of the image-formed product.

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. When the powder ink is developed and fixed to form an ink sheet, the surface of the ink layer forms a homogeneous surface even after repeated thermal transfer and regeneration processes, and the image quality of the image formed does not deteriorate over time. The goal is to provide ink.

[Means for Solving the Problems] The powder ink of the present invention is used in a powder ink used in an image forming method that includes a step of forming an image using a thermal transfer method and a step of recycling an ink sheet. The binder has a penetration rate of 5 or less, a melting point of 60 to 120°C, and a melting point of 100°C.
Polar WAX having a melt viscosity of 10 to 105 CP at
It is characterized by containing 0 to 100 wt%.

[Function] According to the above structure of the present invention, in the powder ink used in the image forming method having the step of forming an image by a thermal transfer method and the step of recycling an ink sheet, polar WAX
By including this, crystallization mainly caused by non-polar WAX can be reduced. Furthermore, compared to non-polar paraffin WAX, etc., it is possible to select a substance with a smaller penetration, and the hardness of the material can be increased, thereby preventing the occurrence of adhesion. Due to these, when an ink layer is formed by fusing on an ink sheet, it is possible to prevent the occurrence of irregularities according to the shape of the powder ink that adheres excessively. Therefore, if the surface of the image forming body is severely uneven, uneven adhesion of the ink layer formed from the powder ink fused to the ink sheet can be prevented.

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

As a binder for the powder ink of the present invention, various wax-like compounds and resins can be used alone or in combination. Examples of WAX-like compounds include plant-based natural waxes such as candelilla wax, carnauba wax, and rice wax; animal-based natural waxes such as beeswax and lanolin; mineral-based natural waxes such as montan wax and osikelite;
paraffin wax, microcrystalline wax,
Natural petroleum waxes such as petrolatum, 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,
One type of wax selected from synthetic waxes such as esters and ketones, or a blend of two or more types can be used. Examples of resins 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, and polyester resins. , polycarbonate resin, cellulose resin, polyarylate resin, polyethylene resin, epoxy resin, urethane resin, phenolic resin,
Thermosetting resins such as melamine resin, urea resin, silicone resin, alkyd resin, polyvinyl alcohol, polyallyl alcohol, polybenzyl alcohol, poly-2-hydroxyethyl methacrylate, polyvinylpyrrolidone, polyvinylpyridine, polyvinylamine, polyallylamine, Simple substances and copolymers of resins selected from resins such as polyvinyl acrylic acid, polyvinyl methacrylic acid, polyvinyl sulfate, polylactic acid, casein, hydroxypropylcellulose, starch, gum arabic, polyglutamic acid, polyaspartic acid, nylon resin, It is 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.

Furthermore, as stated in the claims, the penetration is 5 or less and the melting point is 60.
~120°C, melt viscosity at 100'C 10-1O5cP
Polar WAX is added. This polar WAX is selected from polyethylene oxide, carnauba wax, α-olefin maleic anhydride, montan wax derivative, acid amide, ketone, etc., either singly or in a blend. The penetration here is determined by measuring the penetration as specified in JIS K2235-1980.

In addition to the above-mentioned binder, the powder ink of the present invention also has fluidity,
Additives can be added to an extent that does not impair conductivity, fixing properties, etc. Additives include carbon black, conductive agents such as metal powder, SiO2, TiO2, hydrophobic silica,
Fluidity improvers such as carbon black, metal soaps, zero dispersants such as polyethylene glycol, F e304 , F e
Magnetic powders such as 203, Fe, Cr, Ni, 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 melt mixing, pulverization, and classification, 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. , and 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. 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. The powder ink 11 is supplied onto the ink sheet 1 while applying a bias voltage (hereinafter referred to as "vb") between the electrode 10 and the conductive roller 12 by the voltage M13. 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] As powder ink, paraffin wax 10wt% carnauba wax 37wt% ethylene/vinyl acetate copolymer 7wt% carbon black
Powder ink A1 with a particle size of 10.6 μm was prepared by mixing and kneading 6wt%Fe3O440wt%.
was created.

Powder ink A1 is 18 when subjected to 3Hz abrasion strain.
When the viscosity of 0@C is measured with a flat plate viscometer, it is 9xlO3dy
It was ne/cm2. Volume resistance value of powder ink 106
Ω■, and the volume resistivity when forming the ink layer is l
It was O3Ω■.

Since the resistance value of powder ink A1 was a predetermined low resistance value, image formation and ink sheet regeneration were actually performed by the method shown in FIG. An aramid 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 using a composition consisting of almost the same components as the powder ink A1. Vb was set to 70 V, powder ink was adhered to the ink layer and thermally fixed to regenerate the ink layer. The surface of the regenerated ink layer was observed under a microscope, but no crystals were observed and no powder ink-like protrusions were observed.

Thereafter, an image is formed, and the produced image formed object has a value of 0, D, and 1.8 even on the 1000th playback.
image was formed.

[Comparative Example 1] As a powder ink, paraffin wax 27 wt% carnauba wax 20 wt% ethylene/vinyl acetate copolymer 7 wt% carbon black
6wt%Fe50<4
0 wt % and kneaded to prepare powder ink B1 having a particle size of 10.6 μm.

Powder ink B1 has a shear strain of 18 when given a shear strain of 3 Hz.
When the viscosity at 0°C is measured using a flat plate viscometer, it is 6x103 dy.
n/cm2. The volume resistivity of the powder ink was 103Ω(1).

An aramid film with a thickness of 4 μm was used as the insulating support of the ink sheet, and powder ink B was used as the ink layer.
A composition consisting of almost the same components as 1 was formed to a thickness of 4 μm. The ink layer was regenerated by setting vb to 70V, depositing powder ink on the ink layer, and developing it. However, as a result of microscopic observation, the formation of 2 μm semicircular crystals and 10 μm spherical protrusions were confirmed on the surface of the ink layer.

Furthermore, the image formed object produced by forming an image had an O, D value of 1.0 at the 1000th playback. 8 to 0.
An image with 8 variations was formed.

[Example 2] As a powder ink, α-olefin anhydrous maleic @ 54 wt% carbon black 6 wt% Fe50.
40 wt % and kneaded to prepare powder ink A1 having a particle size of 10.6 μm.

When the viscosity of 180'C of mushrooms is measured with a flat plate viscometer, it is 4 x 1
03 dyne/Cm2. The volume resistivity of the powder ink was 106Ω, and the volume resistivity when the ink layer was formed was 103Ω.

Since the resistance value of the powder-ink A1 was a predetermined low resistance value, image formation and ink sheet regeneration were actually performed by the method shown in FIG. An aramid 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 using a composition consisting of almost the same components as the powder ink A1. Vb was set to 70 V, powder ink was adhered to the ink layer and thermally fixed to regenerate the ink layer. The surface of the regenerated ink layer was observed under a microscope, but no crystal formation or powder ink-like protrusions were found. Thereafter, an image is formed, and the produced image formed object has a value of 0, D, and 1.0 even after the 1000th playback.
8 images were formed.

[Comparative Example 2] As a powder ink, paraffin wax 33 wt% α-olefin anhydrous maleic $ 20 wt% carbon black 6 wt% Fe30n
40 wt% and kneaded to obtain a particle size of 10.6.
A μm powder ink B1 was produced.

Powder ink B1 is 18 when subjected to 3Hz abrasion strain.
When the viscosity at 0℃ is measured with a flat plate viscometer, it is 2xlO' d
It was yn/am2. Volume resistance value of powder ink 106
Ω, and the volume resistivity when the ink layer was formed was 10 3 Ω■.

An aramid film with a thickness of 4 μm was used as the insulating support of the ink sheet, and powder ink B was used as the ink layer.
A composition consisting of almost the same components as No. 1 was formed to a thickness of 4 μm. The ink layer was regenerated by setting vb to 70V, depositing powder ink on the ink layer, and developing it. However, as a result of microscopic observation, the formation of semicircular crystals of 2 μm and spherical protrusions of 10 μm were confirmed on the surface of the ink layer.

Further, the image formed object produced by forming an image has a 0.0. D. Images with variations in value from 1.8 to 0.7 were formed.

[Effects of the Invention] As described above, according to the present invention, powder ink used in an image forming method including a step of forming an image by a thermal transfer method and a step of recycling an ink sheet. The binder has a penetration rate of 5 or less, a melting point of 60 to 120°C,
Polar WA having a melt viscosity of 10-105CP at 100°C
By containing 20 to 100 wt% of X, it has become possible to provide a powder ink that is optimal for image forming methods that use recycled ink sheets. In addition, when an ink sheet is recycled using this powder ink, the number of times it can be recycled can be increased, and the image quality remains stable even after multiple reproductions.
Running costs were significantly reduced. Note that the powder ink of the present invention includes a step of forming an image using a thermal transfer method;
The present invention can be widely applied to devices other than devices using an image forming method that includes a step of recycling and using an ink sheet, such as printers, copying machines, and facsimile machines. 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. 10. . 2゜3゜4゜5゜6゜7゜8゜9゜10゜11゜12゜13゜Ink sheet Insulating support Ink layer Traveling direction of ink sheet Thermal head Traveling direction of recording medium Recording medium Peeling of ink layer Adhering part of the ink layer Electrode Powder ink Conductive roller Power supply 4゜ Powder ink fixing means or more

Claims (1)

[Claims] In the powder ink used in the image forming method that includes the step of forming an image by a thermal transfer method and the step of recycling an ink sheet, the binder used has a penetration value of 5 or less and a melting point of 60 to 120°C. , melt viscosity at 100℃ 10~10^
A powder ink characterized by containing 20 to 100 wt% of polar wax having a weight of 5 cP.