JPS62278089A - Electothermal transfer recording medium - Google Patents

Abstract

PURPOSE:To record images with excellent gradation properties, by providing an ink layer having a construction wherein a heat-fusible ink component comprising a heat- fusible substance being solid at normal temperature and a coloring agent as main constituent is contained in a microporous structure constituted of a resin. CONSTITUTION:This recording medium comprises a current-passing resistor layer 2 provided on one side of a base 1 and an ink layer 3 provided on the other side. The ink layer 3 comprises a heat-fusible ink component 5 contained in a microporous structure 4 constituted of a resin. The recording medium and a receiving sheet 7 are laid one upon the other, an energizing head 8 is pressed against the resistor layer 2 side of the recording medium, and the resistor layer 2 is energized to generate heat. As a result, the ink layer 3 is heated, the ink component 5 is melted to flow out from the inside of the microporous structure 4, and is transferred to the receiving sheet 7, thereby performing thermal transfer recording. The resin constituting the microporous structure is preferably a cellulose resin tending to form a porous structure, and is favorably one having a heat resistance of 100 deg.C. The ink component comprises a heat-fusible substance being solid at normal temperature and a coloring agent. The heat-fusible substance may be, for example, a.thermoplastic resin comprising an olefin homopolymer or copolymer or a derivative thereof.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention and Technical Field] The present invention relates to an electrically conductive thermal transfer recording medium that transfers a recorded image using heat generated by electrical conduction.

[Prior art] In recent years, thermal transfer recording has been used in many fields such as facsimiles, computer terminals, recorders, etc. because it has the characteristics of being non-impact, noiseless, maintenance-free, low cost, small and lightweight, and can be colored. It has been attracting attention.

Among these methods, the method of thermal transfer using a current-carrying head is particularly suitable for full-color recording with intermediate gradation, and is the method that is attracting the most attention as a promising future hard copy method. For example, "Nikkei Electronics" 64
- Page 68, June 25 issue, the method introduced in 1979 and the method described in Japanese Patent Application Laid-Open No. 60-78785 are known, but regarding the gradation of the obtained image, the density Compared to the sublimation thermal transfer recording method which uses a gradation method, it is still not satisfactory.

[Objective] The object of the present invention is to obtain a recorded image with excellent gradation in electrical thermal transfer recording.

[Structure] The present invention provides a recording medium having a support layer and an ink layer that generate Joule heat when energized. This is an electrically conductive thermal transfer recording medium characterized by having a structure containing a heat-melting ink component whose main component is an agent.

This structure will be explained based on the drawings. FIG. 1 shows one example in which a current-carrying resistance layer 2 is provided on one surface of a support 1 and an ink layer 3 is provided on a narrow surface. This ink layer 3 contains a heat-melting ink component 5 in a microporous structure 4 made of resin.

FIG. 2 shows another example in which 1' is a medium-resistance support, on one surface of which a current-carrying resistance layer 2 and an ink layer 3 are sequentially provided. In FIG. 3, a current-carrying layer 6 is provided on one surface of a medium resistance support 1°, and a current-carrying resistance layer 2 and an ink layer 3 are sequentially provided on the other side.

To record an image using such a recording medium, as shown in FIG. 4, the recording medium and the receiving sheet 7 are overlapped, and the current-carrying head 8 is pressed into contact with the current-carrying resistance layer 2 side of the recording medium to apply electricity. , the current-carrying resistance layer 2 is heated to generate heat, the heat is transmitted through the support layer 3, the temperature of the ink layer 3 is raised, and the ink component 5 melts and flows from inside the microporous structure 4. This is thermal transfer recording on the receiving sheet 5 side.

Fig. 4 is an example of what is shown in Fig. 1, but in the case of Fig. 2, the current is applied to the medium resistance support at 1°.
3, and in the case of FIG. 3 the current is passed through the current-carrying layer 6 and the medium resistance support 1°.

In the above, the amount of the ink component 5 that is melted by the thermal energy caused by energization and oozes out from the microporous structure 4 varies depending on the amount of thermal energy applied by energization, and by controlling the amount of energized thermal energy, the amount of ink component 5 that is transferred is transferred. The amount of colorant can be varied, and it is possible to obtain sharp, detailed images with faithful and wide gradations.

Examples of resins that form the microporous structure in the ink layer include polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, cellulose resin, polyester resin, polystyrene, phenol resin, alkyd resin, and epoxy resin. used. However, due to the relationship with the oil described below, those that tend to form porosity are vinyl chloride vinyl acetate copolymer,
Cellulose resins such as cellulose acetate, cellulose butyrate/cellulose acetate, and nitrocellulose are preferred. Also, it is preferable to have heat resistance of 100°C or higher.

The ink components are mainly composed of heat-melting substances and colorants that are solid at room temperature. Examples of heat-melting substances include carnauba wax, paraffin wax, zazol wax, microcrystalline wax, castor wax, and lanolin. Higher fatty acids such as waxes, stearic acid, palmitic acid, lauric acid, aluminum stearate, lead stearate, barium stearate, zinc stearate, zinc palmitate, methyl hydroxystearate, glycerol monodiroxystearate, etc. Derivatives of metal salts, esters, etc.; polyethylene, polypropylene, polyisobutylene, polyethylene wax, polyethylene oxide, polytetrafluoroethylene, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer Thermoplastic resins made of single or copolymers of olefins, such as polymers, or derivatives thereof, are used.

The above heat-melting substances may be used alone or in combination of two or more,
20 to 2 parts per 100 parts of resin constituting the microporous layer
It is used in the proportion of DO part.

Examples of the coloring agent include colored dyes and colored pigments that do not sublimate, but dyes are more preferable for images with gradation.

Examples of such coloring dyes include the following direct dyes, acid dyes, basic dyes, tJX dyes, sulfur dyes, vat dyes, azoic dyes, and oil dyes.

1) Direct dyes; Direct Sky Blue, Direct Black W, etc.

2) Acid dye: Tartrazine, Acid Violet 6
B, Ashidov 7 Strets S 3G, etc.

3) Basic dyes: safranin, auramine, crystal violet, methylene blue, rhodamine B, Victoria blue B, etc.

4) Mordant dyes: Sunchromin Fast Blue MB, Elio from Azurol B1 Alizarin Yellow B, etc.

5) Sulfur dye: Sulfur Brilliant Green 4G, etc.

6) Vat dyes: indanthremble, etc.

7) Azoic dyes: naphthol As, etc.

8) Oil dye: Nigrosine, Spirit Black EB,
Varifast Orange 3206, Oil Black 215
, Butter Yellow, Sudan Blue ■, Oil Red 8
10-Damin B et al.

These dyes are preferably in a dissolved state.

Examples of colored pigments include colored fine particle pigments and monoazo pigments. Examples of colored fine particle pigments include the following. All of them are made by Hex F, and the color index numbers are shown in parentheses.

Permanent Yellow GG, 2 (Pigment Yellow 17), Permanent Yellow DHG Transformer 02
(Pigment Yellow 12), Novopalm Yellow HRO3 (Pigment Yellow 83), Hansa Brilliant Yellow 5GXO2 (Pigment Yellow 74), Permanent Orange RLOI (Pigment Orange 34), Novopalm Red 1-IFG (
Pigment Orange 38), Novopalm Red HF
T (Pigment Red 175), Permanent Lake Red LCLLO2 (Pigment Red 53:1)
), Novopalm Red HF4B (Pigment Red 1
87), Permanent Carmine FB [302 (Pigment Red 14B), Permanent Lupine L6
B (Pigment Red 57: 1), Hostapalm Pink E Trans (Pigment Red 122), Reflex Blue R50 (Pigment Blue 61) In addition, monoazo pigments include compounds represented by the following structural formula.

X-N=N-Y however, X didiazonium salt residue Y: coupler residue Particularly specific examples of product names include the following.

(1) 5ico Fast Yellow D 13
55 (made by BASF) (2) 5ico Fast
Yellow D 1250 (made by BASF F) (3)
The structural formula of Lake Red LC (manufactured by Hoechst) is (4) Lake Red C405 (manufactured by Dainichiseika) (
5) Fast Red 1547 (manufactured by Dainichiseika)
Although the method for producing the ink layer having the above-described structure is not particularly limited, the following method is generally used. That is, the ink is dispersed by mixing and dispersing a heat-fusible substance, a coloring agent, and an oil that serves to form the porosity of the resin together with an appropriate organic solvent using a dispersion device such as an attritor or a ball mill. Obtain a liquid (or a solution). Separately, a solution of the resin dissolved in an organic solvent is obtained, mixed with the ink dispersion, and uniformly dispersed using a mixer such as a ball mill. Next, the resulting dispersion is applied onto a support and dried to obtain a hot-melt ink layer having the above-mentioned fine structure. In the dispersion,
In order to improve the dispersion of the above-mentioned heat-melting substances, colorants and oils (wetting agents, dispersants, etc. may be added), if necessary, fillers commonly used in this type of resin paint may be added. You can also do that.

Alternatively, a substance that is incompatible with the resin that forms the porous structure and is soluble in a solvent that does not dissolve the resin is kneaded with the resin and coated on a support to form a resin layer. A hot-melt ink layer having the above-described structure can also be obtained by dissolving a substance in the above-mentioned solvent to form a porous resin structure, and then filling the porous structure with hot-melt ink components. .

This thickness may be 1 to 30 microns, preferably 2 to 20 microns.

As the oil, any liquid or semi-solid oil can be used as long as it is incompatible with the above-mentioned thermoplastic resin and is non-volatile. Liquid oils include, for example, animal and vegetable oils such as cottonseed oil, rapeseed oil, and whale oil; mineral oils such as motor oil, spindle oil, and dynamo oil; and semisolid oils include, for example, lanolin, lanolin derivatives,
Vaseline, lard, etc. are used.

This oil is preferably a lanolin derivative oil, more preferably an oil of lanolin fatty acid or lanolin fatty acid ester, and specific examples of commercially available oils include Neocoat 0ES-181 and 0ES1.
83, LFC-50M, and LS-3102MB (all manufactured by Yoshikawa Oil Co., Ltd.).

11. As the support used in the present invention, conventionally known films and papers can be used as they are, for example, materials with relatively good heat resistance such as polyester, polycarbonate, triacetylcellulose, nylon, polyimide, aromatic polyamide, etc. Plastic film, cellophane, parchment paper, etc. can be suitably used. The thickness of the support is desirably about 2 to 15 microns in consideration of the conduction efficiency of Joule heat due to energization during thermal transfer.

Further, as the medium resistance support in FIG. 2, a sheet-like material containing the above-mentioned relatively heat-resistant resin as a binder and carbon black as a main component, which is a conductive agent, is used. Here, the proportion of the binder resin and carbon black is suitably 70 to 97% by weight for the former and 3 to 30% for the latter. Medium resistance values are volume resistivity 103~108 Ω-cm, surface resistance 108~10
12 Ω/mouth is desired.

The current-carrying resistance layer is a layer that can generate heat when energized.
The resistance value must be between that of an insulator and a good conductor, and the resistance value is set based on the balance of the amount of electric power applied, the thermal conductivity of the recording sheet, the melting energy of the ink layer, etc. Conventionally, aluminum, copper, iron, tin, zinc, nickel, molybdenum,
A method of forming a resistance layer by dispersing metal powder such as silver in a resin binder (JP-A-56-86790 - JP-A-56-
86793), a method of dispersing iodized steel in a resin binder (Japanese Patent Application Laid-Open No. 51-106445), a method of dispersing zinc oxide and titanium dioxide in a resin binder (Japanese Patent Application Laid-Open No. 51-1993)
3-74047), a method of applying a conductive polymer to a support layer (JP-A-51-106445), a method of dispersing graphite and acetylene black in a resin binder (JP-B No. 56-27382), low-resistance carbon black (JP-A-56-27382), JP-A-60-71293) A method has been proposed in which metals such as aluminum, copper, iron, zinc, tin, nickel, molybdenum, and silver are coated on the support layer by vapor deposition or sputtering. Any method is fine, but
The smaller the resistance value of the current-carrying resistance layer is, the smaller the voltage applied to the current-carrying head can be.Therefore, the capacity of the power supply and head drive system can be reduced, making it more reliable and less expensive.

Therefore, the surface resistance value is preferably 10 6 Ω/lower or less, and more preferably 5×10 5 Ω/lower.

The current-carrying layer, medium-resistance support, and conductive layer in FIG. , polycarbonate, triacetylcellulose, nylon, polyimide, aromatic polyamide, and other resins are used.

Further, in order to further improve the gradation obtained by the present invention, it is also possible to add a gradation control agent to be described later.

In order to maintain the porous resin structure more strongly,
It is also possible to provide an intermediate adhesive layer on the support in advance.

Examples of the intermediate adhesive layer include so-called Plusdec resins and plastic resins with fillers added thereto.

The receiving sheet may basically be plain paper or synthetic paper, but if necessary, it may be made of the above resins, TiO2, silica, ZnO.
It is also possible to apply a filler containing fillers such as the like on plain paper to facilitate the transfer of the colorant.

The aforementioned gradation control agent has better wettability and compatibility with the resin than low-melting substances such as oil and wax, which are the main components of hot-melt ink, and is firmly held in the sponge resin structure. This is to delicately control the pore size of the porous structure to make it smaller. Therefore itself,
It is thought that it is not transferred out even when thermal energy is applied, is retained in the porous structure, and functions as a good gradation control agent by controlling the amount of colorant and ink existing in the surrounding area that transfers.

Specific examples of such gradation control agents include the following.

Acicular crystal pigments: Both inorganic and organic substances can be used, and specific examples include ocher, yellow lead 01 ivy sun cyanine blue, lithore red, Bonmartone light, white clay, and needle crystal pigments. Zinc oxide, 2,7-bis[2-hydroxy-3-(2-chlorophenylcarbamoyl)naphthalen-1-ylazo]-9-fluorenone, 4", 4°'-
Bis[hydroxy-3-(2,4-dimethylphenyl)
Examples include carbamoylnaphthalen-1-ylazo)1,4-distyrylbenzene, but any material can be used as long as the crystals are acicular and the crystals are arranged in a network structure in the transfer layer.

Azo pigment: For example, one having the following chemical structural formula can be used.

X-+N=N-Y)n In the formula, X didiazonium salt residue Y dicoupler residue n: 1.2 or 3 Representative examples include the following.

24- Phthalocyanine pigment: Metal-free phthalocyanine and its derivatives, metal phthalocyanine and its derivatives can be used, and specific examples thereof include the following.

The amount of the gradation control agent added is 0.000% per 1 part by weight of the colorant.
The amount is 5 to 10 parts by weight, preferably 1 to 5 parts by weight.

Next, the present invention will be explained with reference to Examples and Comparative Examples. All parts and percentages are based on weight.

Example 1 A current-carrying resistance layer forming liquid having the following composition was mixed for about 24 hours using a ball mill, and then formed to a thickness of 6 μm using a wire bar.
Coated on the surface of a polyester film and dried at a temperature of 10
It was dried at 0° C. for 1 minute to form a current carrying resistance layer with a thickness of 4 μm.

Carbon black: (Columbia Carbon Pr1ntex 90) 30
80 parts salt vinyl vinyl acetate copolymer M E K
200 parts toluene
Next, 200 parts of the hot melt ink component having the composition shown below is dispersed in a ball mill for about 24 hours with a mixed solution of 175 parts of methyl ethyl ketone and 250 parts of toluene.

Lanolin fatty acid oil (OES-183, manufactured by Yoshikawa Oil Co., Ltd.) 30 parts Carnauba wax (20% toluene mixture) 30 parts Paraffin wax (20% toluene mixture) 30 parts Colorant (manufactured by BASF, Neozapon Blue 8)
07) 30 parts dispersant 1 part liquid paraffin 10 parts Next, 450 parts of a 20% vinyl chloride-vinyl acetate copolymer resin solution (10 parts resin, 20 parts toluene, 20 parts methyl ethyl ketone) was added to the above ink dispersion and stirred for about 1 hour. The mixture was dispersed using a ball mill to prepare a coating of a heat-sensitive transfer composition.

This coating material was applied to the opposite side of the polyester film using a wire bar and dried at a drying temperature of 100° C. for 1 minute to form a heat-melting ink layer with a thickness of about 5 μm. When the surface was observed, a fine porous state (5 to 15 μm in diameter) was observed.

The ink layer of the transfer medium thus obtained was stacked so as to face synthetic paper as a receiver, and an image of a gradation pattern was recorded from the back side of the transfer medium under the following conditions by varying the energization pulse time. As shown in FIG. 5a, a cyan image with excellent gradation was recorded.

Current-carrying recording head density: 6 dOtS/mm Driving applied voltage: 25V Pulse width: 50 μsec to 1.6 msec 32 gradations Example 2 The steps up to the formation of the support and current-carrying resistance layer were the same as in Example 1, except for the hot melt ink layer components. When an image of a gradation pattern was recorded in the same manner except for the following changes, a magenta image with excellent gradation was recorded as shown in FIG. 5b.

Lanolin fatty acid oil (manufactured by Yoshikawa Oil Co., Ltd.: 0ES-183) 30 parts lanolin wax (20% toluene mixture) (manufactured by Yoshikawa Oil Co., Ltd.: HH (
, -82> 60 parts Colorant (manufactured by BASF: Neoz
apon 34B) 30 part powder
1 part liquid paraffin 1
0 copies Example 3 The same procedure as in Examples 1 and 2 was carried out except that only the components of the hot-melt ink layer were changed as shown below, and when an image of a gradation pattern was recorded, the result was as shown in C in Fig. 5. ,
A yellow image with excellent gradation was recorded.

Lanolin fatty acid oil (manufactured by Yoshikawa Oil Co., Ltd.: LFC-50M) 30 parts Montin wax S (20% toluene mixture) (manufactured by Hoechst)
50 parts Colorant (manufactured by BASF: Neozapon yellow
w 073) 25 parts dispersant 1 part liquid paraffin 8 parts Example 4 Same as Examples 1 to 3 except that only the components of the hot-melt ink layer were replaced with those of the following composition. When an image was recorded, a cyan image with excellent gradation was recorded as shown in d of FIG.

Lanolin fatty acid oil (OES-183, manufactured by Furukawa Oil Co., Ltd.) 30 parts Lanolin wax (20% toluene mixture) (FPG-1, manufactured by Yoshikawa Oil Co., Ltd.) 60 parts Colorant (Neozapon Blue)
807, manufactured by BASF) 90 parts Tone control agent = 2,7-bis[2-hydroxy-3-(2
-Chlorphenylcarbamoyl)naphthalen-1-ylazo1-9-fluorenone 20 parts Dispersant 1 part Liquid paraffin 9 parts Comparative Example 1 As in Examples 1 to 3, the support and current-carrying resistance layer are exactly the same, and the heat melting The components of the ink layer were prepared as follows, and dispersed in a three-roll mill to form a heat-melting ink layer having a thickness of approximately 5 μm using a hot-melt method.

Phthalocyanine pigment 20 parts Paraffin wax 20 parts Oxidized wax
40 parts ethylene/vinyl acetate copolymer 20
Part stearic acid 3 parts Almost no fine porous state was observed on this surface.

When an image of a gradation pattern was recorded in the same way,
As shown by X in FIG. 5, an image with poor gradation was recorded.

Comparative Example 2 A hot-melt ink layer was formed by coating using a wire bar in the same manner as in Example 1, except that the resin solution of the vinyl chloride-vinyl acetate copolymer that forms the porous structure was not added.

Similarly, when we recorded the gradation pattern by energization recording, we found that
As shown in y in FIG. 5, an image with poor gradation was recorded.

Example 5 m-Phenylene terephthalamide 9 parts Carbon black (Ketjen black, manufactured by Japan Easy Co., Ltd.) 1 part Calcium chloride 5 parts N-methyl-
A mixture containing 85 parts or more of 2-pyrrolidone was dispersed in a ball mill for 48 hours, and then placed on a glass plate with a gap of 20
The coating was cast using a 0 μm blade, dried in a dryer at 110° C. for 1 hour, and then immersed in cold water at about 5° C. for 1 minute to peel off from the glass plate. Next, after washing in running water at about 20°C, in a wet state, it was stretched twice in each direction, lengthwise and horizontally, and then heat-treated at 300°C for 10 minutes to form a medium resistance support with a thickness of about 20μm. is.

Next, the following resistance layer component mixture was dispersed in a ball mill for about 24 hours in a constant temperature bath at about 60°C, and the coating material was applied to the surface of the support using a wire bar, and the drying temperature was 100°C. This was dried for 1 minute to form a current-carrying resistance layer with a thickness of about 4 μm.

Carbon black (Printex 90: manufactured by Columbia Carbon) 30 parts Polyamide resin (0M4000: manufactured by Toshi) 80 parts Methanol 200 parts Ethanol
200 copies Then, a heat-melting ink layer similar to that in Example 1 was formed and an image was recorded in the same manner as in Example 1. As a result, a cyan image with excellent gradation similar to that in Example 1 was recorded. .

Example 6 The steps up to the formation of the medium resistance support and the current carrying resistance layer were the same as in Example 5, and the following steps were carried out in the same manner as in Example 2. When an image of a gradation pattern was recorded, the same gradation as in Example 2 was obtained. A magenta image with excellent quality was recorded.

Example 7 Images of gradation patterns were recorded in the same manner as in Examples 5 and 6 except that only the components of the hot melt ink layer were replaced with the same ones as in Example 3. Similar gradation properties were obtained. A yellow image with excellent color was recorded.

Example 8 A1 was deposited as a current carrying resistance layer on the support in a vacuum of 10' mmHg to a thickness of about 50,003 mm. Images of gradation patterns were recorded by energization in the same manner as in Examples 5 to 7 except that a thin film layer was provided and a heat-melting ink layer was provided. A color image was recorded.

Comparative Example 3 When an image recording of a gradation pattern was performed by replacing the hot melt ink layer components of Examples 5 to 7 with the same composition as in Comparative Example 1,
An image with poor gradation similar to Comparative Example 1 was recorded.

Comparative Example 4 When a gradation pattern was recorded without adding the resin solution of vinyl chloride-vinyl acetate copolymer forming the porous structure of Example 5, an image with poor gradation similar to Comparative Example 2 was recorded. .

Example 9 A current-carrying resistance layer was formed in the same manner as in Example 1 by subjecting the following resistance layer component mixture to quantum dispersion for about 24 hours using a ball mill in a constant temperature bath at about 60°C.

Carbon black (Printex 90° manufactured by Columbia Carbon) 30 parts Polyamide resin 80 parts Methanol
400 parts of the same heat-sensitive transfer composition as in Example 1 was then prepared, and this coating was applied to the surface of the polyester film on which the current carrying resistance layer was provided using a wire bar, and dried for 1 minute at a drying temperature of 100°C. A heat-melting ink layer having a thickness of approximately 5 μm was formed.

When an image was recorded on the thus obtained transfer medium in the same manner as in Example 1, the same results as in Example 1 were obtained.

Example 10 Example 9 was repeated except that the components of the hot-melt ink layer were replaced with the same components as in Example 2. A magenta image with excellent gradation similar to Example 2 was recorded.

Example 11 The same procedure as Example 9.10 was carried out except that the components of the hot-melt ink layer were replaced with the same ones as in Example 3. A yellow image with excellent gradation similar to that in Example 3 was recorded. Ta.

Example 12 The same procedures as Examples 9 to 11 were carried out except that the components of the hot-melt ink layer were replaced with the same ones as in Example 4. A cyan image with excellent gradation similar to that in Example 3 was recorded. Ta.

Comparative Example 5 When an image of a gradation pattern was recorded by replacing the hot melt ink layer components of Examples 9 to 11 with the same composition as Comparative Example 1, an image with poor gradation similar to Comparative Example 1 was recorded. .

Comparative Example 6 When a gradation pattern was recorded without adding the resin solution of the vinyl chloride-vinyl acetate copolymer that forms the porosity of Example 9, an image with poor gradation similar to Comparative Example 2 was obtained. .

Example 13 A current-carrying layer was obtained by replacing 1 part of carbon black in the medium resistance support of Example 5 with 10 parts of copper powder. Then, the same current carrying resistance layer as in Example 5 was formed.

Next, a mixture of the following formulation was sufficiently dispersed in a constant temperature bath at about 80°C, and this paint was applied onto the current carrying resistance layer using a wire bar, and dried at a drying temperature of 100°C for about 3 minutes to form a coating of about 80°C. A 2μ thick conductive layer was formed.

Carbon black (Printex 90° manufactured by Columbia Carbon) 25 parts Polyvinyl alcohol resin 80 parts Water
500 copies then Example 5
The same hot-melt ink layer was formed.

When an image was recorded on the obtained transfer medium in the same manner as in Example 5, a cyan image with excellent gradation was recorded as in Example 5.

Example 14 The heat-melting ink layer was the same as in Example 2, and the others were as in Example 13.
When an image of a gradation pattern was recorded in the same manner as in Example 2, a magenta image with excellent gradation properties similar to that of Example 2 was formed.

Example 15 When an image of a gradation pattern was recorded in the same manner as in Example 13 except that only the components of the heat-melting ink layer were replaced with the same ones as in Example 3, a yellow color with similar excellent gradation properties was obtained. images were recorded.

Example 16 An image was recorded in the same manner as in Example 13 except that only the components of the hot melt ink layer were replaced with the same ones as in Example 4. As in Example 4, a cyan image with excellent gradation was obtained. recorded.

Comparative Example 7 When an image of a gradation pattern was recorded by replacing the hot melt ink layer components of Examples 14 to 16 with the same composition as Comparative Example 1, an image with poor gradation similar to Comparative Example 1 was recorded. Ta.

Comparative Example 8 When an image of a gradation pattern was recorded by replacing the hot melt ink layer components of Examples 14 to 16 with the same composition as Comparative Example 2, an image with poor gradation similar to Comparative Example 2 was obtained. Ta.

[L effect] As is clear from the above explanation, in the current-applying thermal transfer recording medium of the present invention, ink oozes out from between the porous structures and transfers to the receiving sheet surface depending on the magnitude of the current-applying pulse width, so that the transfer is effected. By controlling the pulse width of the current applied at the time of application, it is possible to obtain transferred images with excellent gradation expression (wide gradation reproduction), and the images have good storage stability. You can also get

[Brief explanation of drawings]

Figures 1 to 3 are explanatory diagrams of each embodiment of the present invention, and Figure 4 is an illustration of each embodiment of the present invention.
The figure is an explanatory diagram of its usage, and FIG. 5 is a graph showing gradation patterns of an example and a comparative example. DESCRIPTION OF SYMBOLS 1... Support body, 1'... Medium resistance support body, 2... Current carrying resistance layer, 3... Ink layer, 4... Fine porous structure, 5... Hot melt ink component, 6... Current carrying layer, 7...
- Receptor sheet, 8... energizing head. Patent Applicant Ricoh Co., Ltd. - Agent Patent Attorney Hide Komatsu Agent Patent Attorney Hiroshi Asahi

Claims (1)

[Claims] In a recording medium that has a support layer and an ink layer that generate Joule heat when energized, the ink layer has a microporous structure made of resin that contains a heat-melting substance that is solid at room temperature and a colorant as its main components. An electrically conductive thermal transfer recording medium characterized by having a structure containing a molten ink component.