JPH02305869A - Powdery ink - Google Patents

Abstract

PURPOSE:To obtain a powdery ink with excellent conductivity and flexibility by incorporating a specified carbon black as a constituted element in an inner nucleus for the powdery ink with an inner nucleus and an outer shell used in an image forming method consisting of a process for forming an image by thermal transfer and a process for regenerating an ink sheet. CONSTITUTION:For a powdery ink with an inner nucleus and an outer shell used in an image forming method consisting of a process for forming an image by thermal transfer and a process for regenerating an ink sheet, a carbon black with a DBP absorption of 200cc/100g or larger is incorporated as a constitutional element.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] 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. For more details, please refer to
3-214441.

[Prior Art] As a conventional powder ink, the present inventors have proposed
No. 214441 describes 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, which mainly contains a waxy compound and carbon black, or The powder has an inner core mainly composed of a waxy compound, a thermoplastic resin compatible with the waxy compound, and carbon black, and an outer shell mainly composed of a resin in which carbon black is dispersed. The powder ink has a volume resistivity of 108 Ωcm or less when the ink is deposited on the ink sheet, and the volume resistivity of the ink layer of the ink sheet recycled with the powder ink is 107 Ωcm or less. We are proposing a certain powder ink.

[Problems to be Solved by the Invention] The inventors of the present invention have conducted extensive studies and found that the amount of additive needed to develop conductivity varies depending on the type of carbon black contained in the inner core of the powder ink. It was found that the characteristics of the powder ink differed depending on the amount of carbon black added. For example, if the amount of carbon black added is increased in order to impart conductivity, the resin content in the powder ink decreases, resulting in problems such as deterioration of the fixability of the powder ink on the ink sheet. there were.

Therefore, the present invention has been made to solve these problems, and its purpose is to 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. Our objective is to provide powder ink. Another object is to provide a powder ink that has excellent conductivity and good fixing properties.

[Means for Solving the Problems] The powder ink of the present invention has an inner core and an outer shell, which are 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. In the powder ink having a DBP oil absorption of 200 c c in the inner core
It is characterized by containing 7100 g or more of carbon black as a constituent element.

[Works] In order for cocarbon black to exhibit electrical conductivity, it is generally required that the carbon black particles have long struts and that the struts can be easily formed. That is, the content of carbon black, which facilitates formation of struttle, can be reduced. The DBP oil absorption is a criterion for determining whether or not it is easy to form this stracture.
It is said that carbon black with a large value can easily form stractures.

Therefore, according to the above structure of the present invention, since the DBP oil absorption is large, the amount of carbon black added for imparting conductivity can be reduced, and the resin content in the inner core of the powder ink can be increased. It becomes possible.

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

The core substance of the powder ink of the present invention is: 1) DBP oil absorption of 200 cc/100 g
It consists of the above carbon black and a substance selected from the substance group listed below.

2) 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 resins, polycarbonate resins, A simple substance, copolymer, or mixture of at BB selected from thermosetting resins such as cellulose resin, polyarylate resin, and polyethylene P4 resin.

3) Polyvinyl alcohol, polyallyl alcohol, polyvinylpyrrolidone, polyvinylamine, polyallylamine, polyvinyl acrylic acid, polyvinyl methacrylic acid, polyvinyl sulfuric acid, polylactic acid, casein, hydroxypropylcellulose, starch, gum arabic, polyglutamic acid, polyaspartic acid , simple substances, copolymers, and mixtures of resins selected from water-soluble resins such as nylon resins.

4) Resin selected from thermosetting resins such as epoxy resin, silicone resin, urethane resin, melamine resin, and alkyd resin.

5) Candelilla wax, carnauba wax, rice wax, beeswax, lanolin, montan wax, osichelite, paraffin wax, microcrystalline wax, berotratum, polyethylene wax, Fischer-Tropsch wax, montan wax derivative, paraffin wax derivative, hydrogenated castor oil, synthetic Waxes such as wax, higher fatty acids such as stearic acid and palmitic acid, polyolefins such as low molecular weight polyethylene, polyethylene oxide, and polypropylene, ethylene/acrylic acid copolymer, ethylene/acrylic acid ester copolymer, ethylene/acetic acid A single substance or a composite selected from olefin copolymers such as vinyl copolymers.

6) Fe30a, Fe20t, Fe, Cr, N
Magnetic powder such as i.

7) Surfactants or dispersants such as metal soaps and polyethylene glycol.

8) Charge control agents such as electron-accepting organic complexes, chlorinated polyesters, nitrofnic acids, quaternary ammonium salts, and pyridinium salts.

9) Fillers such as talc.

10) Fluidity improvers such as SiO2 and TiO2.

11) Furnace black, channel black, thermal black, lamp black, acetylene black,
Colorant for black dyes (dyes and pigments) such as nigrosine.

12) Carbon black such as furnace black, channel black, thermal black, lamp black, acetylene black, metal powder such as A1 powder, Cu powder, IT
Conductive materials such as metal oxide powders such as O powder and SnO2 powder, and organic conductive materials such as quaternary ammonium salts.

Further, the outer shell material of the powder ink of the present invention is made of a material selected from the group of substances 1) to 12) above. In addition, in consideration of the fluidity, blocking property, moisture resistance, long-term storage stability, etc. of the powder ink, it is selected from substance groups 2) and 4) whose softening point or glass transition point is 50°C or higher. It is more desirable to contain the substance as an outer shell material, and it is desirable to contain a substance selected from substance group 12) in order to maintain the conductivity of the powder ink.

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. - For example, mixing, melt-kneading, crushing, and classifying the constituent elements of the core substance of powder ink, or mixing, melt-kneading, and spraying cooling with a spray dryer the constituent elements of the core substance of powder ink. Create an inner core particle by doing this, and then
The outer shell is formed using an encapsulation technique (mechanochemical method, spray drying method, etc.). Note that the outer shell does not need to be one-layered, and may be double or triple-layered.

FIG. 1 schematically shows an image forming method comprising 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.
0, and a conductive roller 12 for supplying powder ink 11 onto the ink sheet 1 from time to time 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 has an electric charge of 1 which is proportional to 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, rough paper, 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, a contact development method, etc., which are known in electrophotography, a heat roll fixing method,
Methods such as a flash fixing method and a pressure fixing method can be applied.

The present invention will be explained in more detail below.

Table 1 shows the DPP oil absorption amount and addition amount y (parts by weight) of carbon black added to the core material of the core particles A1 to El produced in this example.

In addition, as other core substances of carbon black, styrene acrylic copolymer 10 parts by weight paraffin wax 50 parts by weight carnauba wax
50 parts by weight Fe5es
100 parts by weight Ti○2 2
Parts by weight were used.

These were mixed, melt-kneaded, crushed, and classified to produce inner core particles with a volume average particle diameter of 10 μm.

The volume resistivity of these core particles was measured by the pressure cell method. In the pressure cell method, an inner core particle is inserted between two cylindrical electrodes with a diameter of 5 mm to a thickness of approximately 0°5 mm, and a pressure of 1 kg/cm2 is applied in the axial direction, and a 1 ov The resistance of the inner core particles was measured and converted into volume resistivity. The results are also shown in Table 1.

In Table 1, inner core particles are abbreviated as particles, DBP oil absorption as oil absorption, addition amount y as y, and volume resistivity as ρ.

From Table 1, it can be seen that carbon black, which has a small oil absorption amount, needs to be added in a large amount in order to exhibit conductivity.

Table 1 Here, the powder ink used in the image forming method which has the step of forming an image by a thermal transfer method and the step of recycling the ink sheet is the ink of the ink sheet recycled with the powder ink. It is desired that the volume resistivity of the layer is 10 7 Ωcm or less.

Although it is possible to make the volume resistivity of the recycled ink layer 107 Ωcm or less by imparting conductivity to the outer shell, it is possible to achieve this by imparting conductivity to the outer shell only (in other words, if the inner core particles (insulating), there is little guarantee that the ink layer will have uniform conductivity after regeneration. Therefore, it is desirable that the inner core particles also have electrical conductivity.

From the above viewpoint, the inner core particles A3, B3, C3, D2, D3, El, and E having a volume resistivity of 107Ωcm or less
Regarding 2, 5 parts by weight of furnace black and 15 parts by weight of polyester were each formed as an outer shell for 100 parts by weight of the inner core particles, and powder inks a1, b3, c3, d2, d3 were used.
, el, and e2 were created.

These powder inks were used in the image forming method shown in FIG. 1 to evaluate the fixability of the powder inks on an ink sheet. The results are shown in Table 2. In addition, as for the evaluation of fixability,
Adhesion was evaluated by tape peeling, and flexibility was evaluated using a cylindrical rod with a diameter of 10 mm. The results were marked as O: good, △: fair, and ×: poor.

Table 2 From Table 2, when carbon black with low oil absorption is used as the inner core to develop conductivity, the proportion of resin in the powder ink decreases, and therefore the powder ink is fixed on the ink sheet. It can be seen that the quality deteriorates. Note that it is more desirable that the oil absorption amount of the carbon black added to the inner core is 300 cc/g or more because the amount of carbon black added can be reduced.

Note that the image formed on the recording medium using the powder ink with good fixing properties had extremely good image quality.

[Effects of the Invention] As described above, according to the present invention, an inner core and an outer shell 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. In the powder ink having a DBP oil absorption of 2 in the inner core,
00 c c / 100 (Since it contains carbon black which is z or more as a constituent element, the amount of carbon black required to develop conductivity can be reduced,
Therefore, it has become possible to provide a powder ink with good fixability onto an ink sheet.

If an image is formed by 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, so running costs are significantly reduced. It can also be applied to thermal transfer page printers with a built-in ink sheet recycling device.

The powder ink of the present invention can be used in devices using an image forming method including a step of forming an image by a thermal transfer method and a step of recycling an ink sheet, such as devices such as printers, copying machines, and facsimile machines. It can be applied to a wide range of other areas. For example, it can be applied to devices such as printers, copiers, and facsimile machines that use electrophotography.

[Brief explanation of drawings]

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. that's all

Claims (1)

[Claims] (1) In a powder ink that has an inner core and an outer shell and is 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 amount of DBP oil absorbed in the inner core is A powder ink characterized by containing carbon black having a carbon black of 200 cc/100 g or more as a constituent element.