JPH04146184A - Powder ink - Google Patents

Abstract

PURPOSE:To achieve a high image quality, when an image is formed through thermal transfer system on an ink sheet prepared by developing and fixing a powder ink, by adding a terpene resin into the powder ink. CONSTITUTION:A beta-pinene-dipentene copolymer is added, by 2-100wt.%, to a binder such as paraffin wax, carnauba wax or ethylene.vinyl acetate copolymer which is then admixed with carbon black and magnetic powder and ground with wind power to prepare micro particles. Furthermore, super micro particles composed of methacryl resin, carbon black and 10wt.% or less of modified terpene are prepared and applied on the shell of the micro particle through mechanochemical reaction thus producing a powder ink.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to 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.

[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 toners), 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, unless all of the following constraints are satisfied with existing toners, these toners cannot be used as they are. That is, since the ink sheet must be fixed by heating, it is necessary to have a low melting point component, and when the ink sheet is fixed by heating, it is necessary to have a low viscosity component so that it will not peel off during the process. Furthermore, it must be electrically conductive due to process requirements.

The inventors prototyped a powder ink that met these constraints and confirmed that the process was successful. but,
When an image is formed on paper with a somewhat rough surface (hereinafter referred to as rough paper), image quality deterioration such as ink draining is observed, although it is rare.

SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and its purpose is to provide a powder for use 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. To provide a powder ink capable of obtaining good image quality when an image is formed by a thermal transfer method on an ink sheet prepared by developing and fixing the powder ink.

[Means for Solving the Problems] The powder ink of the present invention is a 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 ink is characterized by containing a terpene resin in a weight ratio of 2 to 100%.

Further, the powder ink of the present invention is characterized by having an outer shell containing a terpene resin in a weight ratio of 10% or less.

[Function] According to the above configuration of the present invention, 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, by including a terpene resin, , the adhesive force with the fibers of the paper increases, and the ink sheet adheres more firmly to the paper than the ink sheet side. That is, when the paper and the ink sheet are peeled off, in the heating section, the paper is peeled off with the ink adhered to the entire surface of the paper sheet, and in the non-heating section, the ink sheet is peeled off with the ink adhered to the entire surface of the paper sheet. Therefore, a good image quality with sharp edges without omissions can be obtained.

In addition, it was confirmed that when the powder ink outer shell contains terpene resin at a ratio of 10% or less, the adhesion of the powder ink surface increases and it is possible to prevent the powder ink from coagulating with each other. It was done.

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

As the powder ink of the present invention, one consisting of a binder, adhesive, colorant, internal additive, and external additive can be used as the inner core and outer shell. As the binder, 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,
Thermosetting resins such as cellulose resin, polyarylate resin, polyethylene resin, ethylene vinyl acetate copolymer resin, epoxy resin, urethane resin, phenol resin, melamine resin, urea resin, silicone resin, alkyd resin, polyvinyl alcohol, polyallyl Alcohol, polybenzyl alcohol, poly-2-hydroxyethyl methacrylate, polyvinylpyrrolidone, polyvinylpyridine,
Resin selected from polyvinylamine, polyallylamine, polyvinyl acrylic acid, polyvinyl methacrylic acid, polyvinyl sulfate, polylactic acid, casein, hydroxypropyl cellulose, starch, gum arabic, polyglutamic acid, polyaspartic acid, nylon resin, etc. They are simple substances, copolymers, and mixtures. 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.

Further, as the terpene resin, polyterpene resins such as α-pinene resin, β-pinene resin, limonene resin, camphene resin, P-cymene resin, terpene phenol resin, modified terpene resin, etc. can be used.

In addition, as a coloring agent, carbon black, Fe3O4
Known black colorants such as dyes such as , nigrosine, and known colored colorants such as phthalocyanine can be used.

Internal additives and external additives can be added to the powder ink of the present invention to the extent that its fluidity, conductivity, fixability, etc. are not impaired. Internal additives include conductive agents such as carbon black and metal powder, fluidity improvers such as SiO2, TiO□, hydrophobic silica, and carbon black, metal soaps, dispersants such as polyethylene glycol, Fe3O4, Fe2O3,
Magnetic powders such as 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. 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 powder ink filling rate is 9.
If it is 0%, the average particle size of the powder ink is 9.5 to 1
The thickness is preferably 0.5 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 HH part 8 of the ink layer exhibits insulating properties. 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, HP 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 a powder ink, paraffin wax 18wt% carnauba wax 20wt% ethylene/vinyl acetate copolymer 8wt% β-pinene/dipentene copolymer
12wt% carbon black 2wt
% magnetic powder and 40 wt % of the powder were mixed and kneaded, and then air-pulverized to produce fine particles with an average particle size of about 10 μm. Further, 10 parts by weight of carbon black was externally added to the fine particles to prepare powder ink A1 having a particle size of 11.2 μm.

When powdered ink A1 was observed using a transmission electron microscope, an outer shell made of carbon black of about 0.2 μm was confirmed. 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 powder ink A1 was a predetermined low resistance value, image formation and ink sheet regeneration were actually performed by the method shown in FIG. As an insulating support for the ink sheet, 4
Using an aramid film with a thickness of .mu.m, powder ink was attached to the ink layer with Vb set to 70 V, and the powder ink on the film was thermally fixed to form an ink layer. The created ink sheet is printed on commercially available PP using a thermal head.
An image was formed on C paper. In the ink layer, no defects such as omission of details were observed. Similarly, 1000 PP
An image was formed on C paper, but no unevenness or omissions were observed in the image formation. At this time, the oD value (temperature measured by an optical density system) at the solid portion was 2.0. Furthermore, when the ink sheet used for image formation was recycled,
It was confirmed that the ink sheet was completely regenerated. Image formation was carried out using the recycled ink sheet, but no unevenness or omissions in image formation were observed in the produced image-formed product even after the 100th reproduction. Furthermore, the oD value of the solid portion at that time was constant at 2.0.

[Comparative Example 1] As a powder ink, paraffin wax 18 parts by weight Carnauba wax 20 parts by weight Ethylene-vinyl acetate copolymer 8 parts by weight Carbon black
2 parts by weight of magnetic powder and 40 parts by weight were mixed and kneaded, and carbon black was externally added in the same manner as in Example 1 to prepare powder ink B1.

Powder ink B1 was observed to have an outer shell of carbon black of about 0.2 μm when observed using a transmission electron microscope. In addition, the volume resistance value of each powder ink is 106Ω for each country,
Also, the volume resistivity when forming the ink layer is 103Ω
It was the mouth.

Since the resistance value of the powder ink B1 was a predetermined low resistance value, image formation and ink sheet regeneration were actually performed by the method shown in FIG. As an insulating support for the ink sheet, 4
Using an aramid film with a thickness of .mu.m, powder ink was attached to the ink layer with Vb set to 70 V, and the powder ink on the film was thermally fixed to form an ink layer. The created ink sheet is printed on commercially available PP using a thermal head.
An image was formed on C paper. In the ink layer, no defects such as omission of details were observed. Similarly, 1000 PP
An image was formed on C paper, but unevenness, skipping, etc. occurred in the image formation at a rate of 12.5%.

At this time, the OD value (temperature measured by an optical density system) at the solid portion was 1.8 to 2.0. Furthermore, when the ink sheet used for image formation was recycled, it was confirmed that the ink sheet could be completely recycled. Image formation was carried out using the recycled ink sheet, but unevenness, skipping, etc. in image formation were observed in the produced image-formed products at a rate of once every third time the ink sheet was recycled.

[Example 2] As a powder ink, modified terpene resin 58wt% (YS Resin To-85, Yasuyu Kogyo) carbon black
2wt% magnetic powder
40 wt% were mixed and kneaded, and then air-pulverized to produce fine particles with an average particle size of about 10 μm. Furthermore, 10 parts by weight of carbon black was externally added to the fine particles to reduce the particle size to 10.
．． Powder ink A2 of 8μ was produced.

Powder ink A2 was observed to have an outer shell of carbon black of approximately 0°2 μm when observed using a transmission electron microscope. 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 powder ink A1 was a predetermined low resistance value, image formation and ink sheet regeneration were actually performed by the method shown in FIG. As an insulating support for the ink sheet, 4
Using a μm thick aramid film, set the VB to 70V to adhere powder ink to the ink layer, and heat fix the powder ink on the film to create an ink layer.0 Transfer the created ink sheet to the thermal head commercially available PP using
An image was formed on C paper. In the ink layer, no defects such as omission of details were observed. Similarly, 1000 PP
An image was formed on C paper, but no unevenness or omissions were observed in the image formation. At this time, the OD value (temperature measured by an optical density system) at the solid portion was 2.0. Furthermore, when the ink sheet used for image formation was recycled,
It was confirmed that the ink sheet was completely regenerated. Image formation was carried out using the recycled ink sheet, but no unevenness or omissions in image formation were observed in the produced image-formed product even after the 100th reproduction. Furthermore, the OD value of the solid part at that time was 2. It was constant at 0.

[Example 3] As a powder ink, modified terpene resin x wt% paraffin wax 58-xwt% carbon black
2 wt% magnetic powder 40
wt%, mixed, kneaded, and air-pulverized to an average particle size of approximately 1.
Fine particles of 0μ were created. Furthermore, for fine particles, 1
Added 0 parts by weight of carbon black externally, particle size 10.8μ
A powder ink was prepared.

When observed with a transmission electron microscope, the powder ink shows approximately 0
．． An outer shell consisting of 2μ carbon black was confirmed. 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 was a predetermined low resistance value, image formation and ink sheet regeneration were actually performed by the method shown in FIG. 4 μm as an insulating support for the ink sheet
Using a thick aramid film, apply powder ink to the ink layer by setting VB to 70V, and heat fixing the powder ink on the film to create an ink layer. 1. Place the created ink sheet through a thermal head. An image was formed on commercially available PPC paper using the following method. 1000 PPCs under the same conditions
Images were formed on paper, and the unevenness, skipping, etc. of image formation was observed, and the relationship between the number of sheets where such occurrences occurred and the amount of modified terpene resin added is shown in FIG. From Figure 2, hydrogenated terpene is 1wt%
With the above, the improvement in image quality is recognized. Furthermore, 10wt%
Above that, the effect becomes more noticeable.

[Example 4] As powder ink, paraffin wax 5wt% polyethylene wax 30wt% modified terpene resin
15wt% ethylene vinyl acetate copolymer
'8wt% carbon black 2wt
% magnetic powder and kneaded to prepare fine particles with an average particle size of about 10 μm. Furthermore, 100-x parts by weight of methacrylic resin 6 parts by weight of carbon black Modified terpene resin
Ultrafine particles having a particle size of 0.2 μm were prepared by X parts by weight, and externally added to the outer shell of the fine particles by mechanochemical reaction to prepare a powder ink.

When observed with a transmission electron microscope, the powder ink shows approximately 0
．． An outer shell consisting of 2μ carbon black was confirmed. The volume resistivity of the powder ink was 106Ω, and the volume resistivity when the ink layer was formed was 103Ω.

The powder ink was left in a constant temperature bath at 60° C. for 300 hours, and changes in particle size observed under a microscope were investigated. The results are shown in Figure 3. 10wt of modified terpene resin in the outer shell
If more than % is added, significant particle aggregation will be observed.

Since the resistance value of the powder ink was a predetermined low resistance value, image formation and ink sheet regeneration were actually performed by the method shown in FIG. 4 μm as an insulating support for the ink sheet
Using a thick aramid film, powder ink was attached to the ink layer with Vb set to 70 V, and the powder ink on the film was thermally fixed to create an ink layer. An image was formed on commercially available 220 paper using the prepared ink sheet using a thermal head. Regardless of the amount of terpene-based resin in the outer shell, no small details were observed in the ink layer. In the same manner, images were formed on 1000 sheets of PPC paper, but no unevenness or omissions in image formation were observed. Furthermore, when the ink sheet used for image formation was recycled, it was confirmed that the ink sheet could be completely recycled.

[Example 4] As a powder ink, paraffin wax 33wt% α-olefin maleic anhydride 20wt% carbon black
Mixed with 6wt% terpene phenol magnetic powder and 40wt%,
The mixture was kneaded and air-pulverized to produce fine particles with an average particle size of about 10 μm. Further, 10 parts by weight of carbon black was externally added to the fine particles to prepare a powder ink having a particle size of 12.6 μm.

When observed with a transmission electron microscope, the powder ink shows approximately 0.
An outer shell consisting of 2μ carbon black was confirmed. 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 was a predetermined low resistance value, image formation and ink sheet recycling were actually performed using the method shown in Figure 1. 4 μm as an insulating support for the ink sheet
Using a thick aramid film, powder ink was attached to the ink layer with Vb set to 70 V, and the powder ink on the film was thermally fixed to create an ink layer. An image was formed on commercially available PPC paper using the created ink sheet using a thermal head. No defects such as omission of details were observed in the ink layer. In the same manner, images were formed on 1000 sheets of PPC paper, but no unevenness or omissions in image formation were observed. At this time, the oD value in the solid part was 2.0. Furthermore, when the ink sheet used for image formation was recycled, it was confirmed that the ink sheet could be completely recycled.

Image formation was performed using recycled ink sheets, but
Even after the 100th playback of the produced image-formed product, no unevenness or omission of image formation was observed. Furthermore, the OD value of the solid portion at that time was constant at 2.0.

Although not mentioned in this example, the same effect can be obtained when a terpene resin is used as described above, or when a resin system is used instead of a wax system as the main binder. That is self-evident.

[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, By containing the terpene resin in the ink at a weight ratio of 2 to 100% of the binder, it is possible to obtain good image quality that eliminates the omission of fine lines and unevenness when forming images. can. In addition, since the powder ink has an outer shell containing terpene resin at a weight ratio of 10% or less, aggregation of the powder ink can be prevented, and an image forming method in which the ink sheet is recycled and used. Now we can provide the best powder ink for. When an ink sheet is recycled using this powder ink, image quality remains stable even after multiple recycles, which increases the number of recycles and significantly reduces running costs. Ta. The powder ink of the present invention can be widely applied to devices that form an image on an image forming body such as paper by heat or pressure, such as printers, copiers, facsimile machines, etc. that use an electrophotographic process or a thermal transfer process. .

[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. FIG. 2 is a diagram showing the results of an experiment to investigate the amount of terpene resin in the powder ink of the present invention and the occurrence of image quality deterioration when forming an image using the powder ink. Figure 3 shows the amount of terpene resin in the outer shell of the powder ink of the present invention and the amount of terpene resin at 60°C.
FIG. 2 is a diagram showing the experimental results of examining changes in particle diameter when left for 00 hours. 116. Ink sheet 2゜3゜4゜5゜6゜7゜8゜9゜10゜11゜12゜13゜14゜ Insulating support Ink layer Travel direction of ink sheet Thermal head Travel direction of recording medium Recording medium ink layer Peeling part Adhering part of ink layer Electrode Powder ink Conductive roller Power supply Powder ink fixing means Applicant Seiko Epson Corporation Agent Patent attorney Kizobe Suzuki (1 person) Figure 2

Claims (2)

[Claims] (1) In 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, a terpene-based resin is used as a binder in the powder ink, A powder ink containing 2 to 100% by weight. (2) The powder ink according to item 1, which has an outer shell containing a terpene resin in a weight ratio of 10% or less.