JPH0278595A - Powder ink and printer - Google Patents

Abstract

PURPOSE:To prevent the deterioration of an ink layer caused by a heat history by incorporating antioxidant in the composition of a powder ink. CONSTITUTION:An antioxidant is contained in a powder ink. As a wax compound as a main component of the powder ink, a vegetable natural wax, an animal natural wax, a mineral natural wax, a synthetic wax, and the like are used. For binding the wax, an acrylic resin, a styrene resin, a butyral resin, a nylon resin, and the copolymer or crosslinked material of the aforesaid resins can be used. As the antioxidant, phenols or amines as a radial chain inhibitor, sulfides, phosphites, or mercaptans as a peroxide decomposer, and a chelating agent as a metal inactivating agent can be used in a single or mixed form. As a coloring material, carbon blacks and pigments or dyes can be used. As magnetic powder, fine powder of a magnetic material, such as ferrite, magnetite, and iron, is used. In this manner, the deterioration of an ink sheet caused by a heat history can be prevented, and a sufficient optical density can be obtained even after a large number of printing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a printing apparatus having a step of forming an image by a thermal transfer printing method and a step of regenerating an ink sheet using electrostatic force. Furthermore, patent application No. 63-38113
．． Concerning improvements in Japanese Patent Application No. 63-36115.

[Prior Art] Conventionally, as a thermal transfer printing method, a thermal head is pressed against an ink sheet formed with ink mainly composed of wax and a coloring material, and the image area is heated and melted, and the molten ink is transferred onto a recording medium. A commonly used method is to transfer and print.

In addition, as a thermal transfer printing device that recycles and uses an ink sheet, a printing device that has a step of forming an image by a thermal transfer printing method and a step of regenerating the ink sheet using electrostatic force is disclosed in Japanese Patent Application No. 63-36113. As a method for recycling ink sheets, Japanese Patent Application No. 63-36115 and the like have been proposed.

[Problem M to be solved by the invention] However, powder ink used in a printing device that has a step of forming an image using a conventional thermal transfer printing method and a step of recycling an ink sheet using electrostatic force is The body ink adheres to the ink sheet and forms an ink layer by heating and melting, printing is performed using a thermal transfer printing method, and the ink layer is regenerated by supplying powder ink to the printed area that has peeled off by printing again. The ink portion that is not coated has a problem in that heat history accumulates, causing deterioration of the ink layer, and printing quality deteriorates due to multiple printings.

The present invention is intended to solve these problems, and its purpose is to provide powder ink that does not cause deterioration of the ink layer due to thermal history, and printing that does not deteriorate print quality even after multiple printings. It is located where the equipment is provided.

[Means for Solving the Problems] The printing apparatus of the present invention uses powder ink used in an image forming method 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. It is characterized by containing an antioxidant. Furthermore, it is characterized in that printing is performed using this powder ink.

[Function] According to the above configuration of the present invention, in the step of printing by a thermal transfer printing method and subsequently supplying powder ink to the printed portion peeled off by printing to regenerate the ink layer, the ink layer is regenerated without being printed. Thermal history accumulates in the ink section left unused. As a result, waxes and resins in the ink are activated by heat,
Deterioration occurs due to the generation of radicals and peroxides due to oxygen and ozone, the scission of molecular chains, and the acceleration of these reactions due to residual metals, which denatures the ink sheet, reduces transferability, and reduces print quality. .

Therefore, the powder ink of the present invention contains a radical chain inhibitor,
By adding antioxidants such as peroxide decomposers and metal deactivators, it is possible to prevent deterioration of the ink sheet and provide a printing device with stable printing quality.

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

[Example] The waxy compound which is the main component of the powder ink of the present invention includes natural vegetable waxes such as candelilla wax, carnauba wax and rice wax, natural animal waxes such as beeswax and lanolin, montan wax, Mineral natural waxes such as 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, paraffin wax derivatives, and hardened waxes. Hydrogenated waxes such as castor oil and hydrogenated castor oil derivatives, synthetic waxes such as fatty acids, acid amides, esters, and ketones are used, and these waxes can be used alone or in combination. In addition, for binding wax, 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, Thermoplastic resins such as polyester resins, polycarbonate resins, cellulose resins, polyarylate resins, polyethylene resins, vinyl acetate resins and their copolymers, phthalate esters, adipate esters, sebacate esters,
It is also possible to add plasticizers such as phosphoric acid esters and modified epoxies. Furthermore, thermosetting resins such as epoxy resins, urethane resins, phenolic resins, melamine resins, urea resins, silicone resins, and alkyd resins, polyvinyl alcohol, polyallyl alcohol, polybenzyl alcohol, poly-2-hydroxyethyl methacrylate,
Polyvinylpyrrolidone, polyvinylpyridine, polyvinylamine, polyallylamine, polyvinyl acrylic acid,
polyvinyl methacrylic acid, polyvinyl sulfate, polylactic acid,
casein, hydroxypropyl cellulose, starch,
Gum arabic, polyglutamic acid, polyaspartic acid, nylon resin, and copolymers and crosslinked products of these resins can be used.

Antioxidants include phenols such as dibutylmethylphenol, methylenebis(methylbutylphenol), and tris(methylhydroxybutylphenol), amines such as phenylnaphthylamine, propyldiphenylamine, and bis(phenylamino)ethane, and radical chain inhibitors. Sulfides such as dilaurylthiodiprobinate and distearylthiodi as oxide decomposers;
Phosphites such as tridecyl phosphite, diphenyldecyl phosphite, triphenyl phosphite,
Mercaptans such as mercaptobenzothiazole and mercaptobenzimidazole, and chelating agents such as aromatic amines, acid amides, and hydrazides as metal deactivators are used, and these can be used alone or in combination. Antioxidants can be added to waxes and resins up to their saturation temperature, but in order to maintain the properties of powder inks, antioxidants can be added to waxes and resins up to a maximum of 20%
It is possible to add up to wt%.

Coloring materials include carbon blacks such as furnace black, lamp black, and acetylene black for black colors, benzidine yellow and disazo yellow for yellow colors, carmine 6B, Lake Red C, pigment scarlet, and quinacridone for red colors, and carbon blacks for blue colors. Facial dyes such as phthalocyanine blue and ink-threne blue are used.

As the magnetic powder, fine powder of a magnetic material such as ferrite, magnetite, iron, chromium, or nickel is used.

As a method for producing the powder ink of the present invention, a method known as a method for producing toner for electrophotography can be applied, and the powder ink is produced by melting and kneading raw materials for powder ink, pulverizing, and classifying. Moreover, a powder ink can also be produced by spray-drying a molten mixture. Furthermore, in order to improve storage stability, it is also possible to form an outer shell mainly composed of resin on the surface of the powder ink. The method for making this outer shell is as follows:
Powder ink is dispersed in a solution that dissolves the resin for the outer shell but does not dissolve the powder ink, and after dissolving the resin for the outer shell, the powder ink having a resin outer shell is prepared by spraying N and drying. It can be made.

FIG. 1 shows an image forming method using a printing apparatus, which includes a step of forming an image by a thermal transfer printing method using powder ink of the present invention, and a step of recycling an ink sheet using electrostatic force.

In the step of forming an image by a thermal transfer printing method, an ink sheet 3 having an ink layer 2 on an insulating support 1 is placed in the direction indicated by an arrow 4.
The thermal head 5 transfers ink to the recording medium 7 traveling in the direction of the arrow 6, thereby forming an image on the recording medium 7. By forming the image, an ink layer peeling portion 8 and an ink layer adhesion portion 9 are formed on the ink sheet 3. Subsequently, in the step of recycling the ink sheet, the electrode 10 is placed in contact with the insulating support 2 of the ink sheet 3, and the electrode 1 is placed in contact with the insulating support 2 of the ink sheet 3.
A conductive roller 12 that sequentially supplies the powder ink 11 onto the ink sheet 3 is disposed on the opposite side of the ink sheet 3, and a bias voltage is applied between the electrode 10 and the conductive roller 12 by the power source 13, and the powder ink 11 is is supplied onto the ink sheet 3. The powder ink 11 that has come into contact with the ink layer peeling part 8 of the ink sheet 3 is charged with an amount proportional to the product of the capacitance of the insulating support 1 and the bias voltage because the ink layer peeling part 8 exhibits insulating properties. The injected material adheres to the insulating support 1 by electrostatic force. However, the ink layer adhering portion 9 of the ink sheet 3
, and the powder ink 11 attached to the insulating support 1
The powder ink 11 that has come into contact with the ink layer 2 and the powder ink 11 are conductive and form a conductive path, so no adhesion force is generated. The replenished powder ink 11 is fixed onto the insulating support 1 by the ink fixing device 14, and the ink layer 2
The ink sheet is recycled. As the insulating support of the ink sheet used here, a resin film such as polyethylene terephthalate, polyaramid, polyimide, etc. can be used, and as the thermal head 5, in addition to the head used in the fusion heat transfer method, etc. A stylus head used in can also be used, and in the case of an electrically conductive thermal transfer method, 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, methods such as a magnetic brush development method and a contact development method, which are known in the electrophotographic method, can be applied, and as the powder ink fixing device 14, similarly known electrophotographic methods can be applied. A heat roll fixing method, a flash fixing method, etc., which are known in the art, can be applied.

[Example 1] As a powder ink, paraffin wax 25wt% carnauba wax 25wt% ethylene/vinyl acetate copolymer 30wt% carbon black
5 wt% 2.2'-methylenebis(4-methyl-6-t-butylphenol) 1 wt% was melt-kneaded to produce particles with a particle size of 12 μm, followed by 10 wt% styrene-acrylic copolymer and 4 wt% carbon black. A powder ink was prepared by externally adding it by a spray drying method. A printing test was conducted using this powder ink by forming an image and recycling an ink sheet using the method shown in FIG. Note that a 4 μm thick polyethylene terephthalate film was used as an insulating support for the ink sheet. Further, as an image forming method, a 1 mm long single line was written in parallel to the moving direction of the ink sheet, and the writing portion was moved in the lateral direction for each cycle to observe changes in the number of cycles and print quality. The results are shown in Table 1.

Table 1 Printing temperature: Optical temperature of image on recording medium Ink layer peeling part temperature: Optical density of ink layer peeling part temperature As shown in Table 1, the ink sheet made with the powder ink of the present invention has No deterioration due to heat history, 200
A printing device capable of obtaining a sufficient optical temperature even after printing twice was obtained.

[Comparative Example 1] As a powder ink, paraffin wax 26 wt% carnauba wax 25 wt% ethylene/vinyl acetate copolymer 30 wt% carbon black 5 wt% were melt-kneaded and the particle size was 12 μm.
Then, 10 wt % of styrene-acrylic copolymer and 4 wt % of carbon black were added externally by spray N drying method to prepare powder ink. A printing test was conducted using this powder ink in the same manner as in Example 1. The results are shown in Table 2.

Table 2 Printing wetness: Optical density of the image on the recording medium Temperature at the part where the ink layer is peeled off: Optical density at the part where the ink layer is peeled off Deterioration occurred and the print quality decreased with the number of cycles.

[Example 2] As a powder ink, microcrystalline wax 15 wt% oxidized polyethylene wax 15 wt% ethylene/vinyl acetate copolymer 10 wt% carbon black 4 wt% magnetite
35 wt% dilauryl thiodipropionate 3 wt% EDTA
7 wt% was melt-kneaded to produce particles with a particle size of 10 μm, and then 7 wt% of acrylic resin and 4 wt% of carbon black were externally added by a spray drying method to produce a powder ink. A printing test was conducted using this powder ink by forming an image and recycling an ink sheet using the method shown in FIG. A 4 μm thick polyaramid film was used as the insulating support of the ink sheet, and a magnetic conductive roller was used. A printing test was conducted using this powder ink in the same manner as in Example 1.

The results are shown in Table 3.

Table 3 Print density: Optical temperature of image on recording medium Density at ink layer peeled part: Optical density at temperature at ink layer peeled part As shown in Table 3, ink sheets made with the powder ink of the present invention have No deterioration due to heat history, 100%
A printing device capable of obtaining a sufficient optical temperature even after printing twice was obtained.

[Comparative Example 2] As a powder ink, microcrystalline wax 20 wt% oxidized polyethylene wax 20 wt% ethylene/vinyl acetate copolymer 10 wt% carbon black
4 wt% magnetite
35 wt% was melt-kneaded to produce particles with a particle size of 10 μm, and then 7 wt% of acrylic resin and 4 wt% of carbon black were added externally by a spray drying method to produce a powder ink. A printing test was conducted using this powder ink in the same manner as in Example 2. The results are shown in Table 4.

Table 4 Print density: Optical density of the image on the recording medium Temperature of the ink layer peeled part: Optical temperature of the ink layer peeled part density As shown in Table 4, powder ink that does not contain antioxidants depends on the thermal history. Deterioration occurred and the print quality decreased with the number of cycles.

[Effects of the Invention] As described above, according to the present invention, powder used in an image forming method comprising a step of forming an image by a thermal transfer printing method and a step of recycling an ink sheet using electrostatic force. For ink, we use powder ink that contains antioxidants in the wax that is the main component of the ink, and by printing with this powder ink, the ink sheet does not deteriorate due to heat history and can be used in large numbers. A printing device capable of obtaining a sufficient optical temperature even after printing twice 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 explanation of the drawing]

FIG. 1 is a diagram illustrating an image forming method of a printing apparatus, which includes a step of forming an image by a thermal transfer printing method using powder ink of the present invention, and a step of recycling an ink sheet using electrostatic force. 1, insulating support 2, ink layer 3, ink sheet 4, moving direction 5, thermal head 6, moving direction 7, recording medium 8, ink layer peeling section 9, ink layer adhesion section 10, electrode 11, Main ink 12, conductive roller 13, power supply 14, ink fixation device Applicant: Seiko Epson Co., Ltd. Agent: Patent Attorney Tosuzu Home Base Third Department (1 person)

Claims (2)

[Claims] (1) Powder ink used in an image forming method that includes a step of forming an image by a thermal transfer printing method and a step of regenerating an ink sheet using electrostatic force, which contains an antioxidant in its composition. Powder ink characterized by: (2) A printing device comprising a step of forming an image by a thermal transfer printing method and a step of recycling an ink sheet using electrostatic force, the printing device characterized in that it uses a powder ink containing an antioxidant.