JPS61295077A - Heat sensitive transfer recording - Google Patents

Abstract

PURPOSE:To reduce recording cost and to enable a good printing even on a surface of recording medium which lacks smoothness, by causing a conductive, intermediate transfer recording medium to generate Joule heat in pattern, and by directly supplying the heat to a heat fusion type ink layer of a heat sensitive transfer material. CONSTITUTION:One of the surfaces of an endless belt shaped, conductive, intermediate transfer medium 4, while being held by a recording electrode 5 and a platen 6, is brought in contact with an ink layer 2 of a heat sensitive transfer material. The transfer medium 4 is applied with a pattern voltage from the recording electrode 5, and an electric current flows from a conductive layer 41 and a conductive metal layer 42 to a return electrode 7, and the conductive layer 41 which is immediately under the recording electrode 5 generates Joule heat in pattern. The heat fusion type ink which is fused or softened by the above heat generation forms an ink image 22 on the intermediate transfer medium, and moves downward. The surface which has the ink image 22 is brought in touch with a recording medium 9 at a pressure roll 8, and re-transferring takes place to the recording medium 9 by the pressure between the rolls 8 and 10. Therefore, the necessity for the conductivity of the substrate of heat sensitive transfer material and the ink layer is eliminated, and the intermediate transfer medium may be repeatedly used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes Joule heat generated when a patterned voltage is applied to a conductive support that supports a heat-melting ink layer of a heat-sensitive transfer material. The present invention relates to an improvement in a conventional so-called recording electrode type thermal transfer recording method for transferring heat-melting ink from a thermal transfer material to a recording medium.

11. The thermal transfer recording method has the characteristics that it can record on plain paper, and the equipment used is compact and noiseless, and has recently begun to be widely used.

This heat-sensitive transfer recording method generally uses a heat-sensitive transfer material formed by coating a sheet-like support with a heat-melt ink made by dispersing a colorant in a heat-melt binder. The heat-melting ink layer is superimposed on the recording medium so as to be in contact with the recording medium, and by supplying patterned heat to the ink layer, the melted ink is transferred to the recording medium, and the heat supply shape is applied onto the recording medium. It forms a recorded image according to the

In such a thermal transfer recording method, as a method for supplying patterned heat to the heat-melting ink layer, there is a conventional method of supplying heat from the support side of the thermal transfer material using an external heat generating member such as a thermal head. (hereinafter referred to as "thermal head method")
In addition, there is a method in which a patterned voltage is applied to a conductive support or ink layer, and the support or the ink layer itself generates heat using Joule heat to supply heat to the ink layer (
A method (hereinafter referred to as the "recording electrode method") has been proposed. This recording electrode system has the characteristics that the recording speed is high because there is no need for cooling time for the dots constituting the recording electrode, and the thermal efficiency is high because the support or the ink layer itself generates Joule heat.

However, in the conventional recording electrode type thermal transfer recording method, conductive fine particles are uniformly dispersed in the support of the thermal transfer material or in the heat-melting ink layer, or a metal film is deposited between the support and the ink layer. Since it is necessary to provide a conductive layer consisting of a heat-sensitive transfer material, the heat-sensitive transfer material is expensive, and since the heat-sensitive transfer material is disposable and cannot be used repeatedly, there is a drawback that the recording cost increases.

In addition, in conventional thermal transfer recording methods as well as the recording electrode method, heat-melting ink cannot adhere to the concave portions of the surface of a recording medium with low smoothness, and when printing on a recording medium with low smoothness, it is difficult to print. The disadvantage is that the quality deteriorates.

In order to eliminate these drawbacks, proposals have been made to use hot-melt ink with a low melt viscosity or to increase the pressing force of a thermal head or the like. However, when using hot-melt ink with low melt viscosity,
The ink layer becomes sticky even at relatively low temperatures, resulting in a decrease in the storage stability of the thermal transfer material and staining of non-printed areas of the recording medium during thermal transfer recording. In addition, when the pressing force of a thermal head, etc. is increased, head durability decreases due to increased wear on the head surface, meandering of the thermal transfer material, etc.
This causes running defects such as wrinkles.

The main object of the present invention is to eliminate the drawbacks of the conventional thermal transfer recording method mentioned above, maintain the advantages of the recording electrode method, reduce the recording cost, and reduce the surface smoothness. It is an object of the present invention to provide a thermal transfer recording method that can provide good printing even on a recording medium.

As a result of research for the purpose stated in -, the inventor applied a voltage to a conductive intermediate transfer medium to cause the intermediate transfer medium itself to generate heat in a pattern, and to sense this heat. Directly supplying the ink to the heat-melting ink layer of the thermal transfer material to selectively melt or soften the ink and transfer it to the intermediate transfer medium, and then press-transfer the ink image on the intermediate transfer medium to the recording medium. was found to be extremely effective.

The thermal transfer recording method of the present invention is based on such knowledge, and more specifically, the ink layer side of a thermal transfer material comprising a layer of heat-fusible ink provided on a support is coated with a conductive intermediate layer. selectively transferring the heat-melting ink to the intermediate transfer medium by contacting one surface of the transfer medium and applying a patterned voltage to the surface of the intermediate transfer medium opposite to the surface in contact with the heat-sensitive transfer material; and a step of bringing the surface of the intermediate transfer medium to which the ink is adhered into contact with a recording medium, and press-transferring the ink image of the intermediate transfer medium-L onto the recording medium.

In the thermal transfer recording method of the present invention, Joule heating is generated in a conductive intermediate transfer medium in a pattern, and this heat is directly supplied to the heat-melting ink layer of the thermal transfer material. support for thermal transfer material,
Since the ink layer does not need to be electrically conductive and the electrically conductive intermediate transfer medium can be used repeatedly, recording costs can be reduced. Further, since heat is directly supplied to the heat-melting ink layer, the support of the heat-sensitive transfer material does not need to have heat resistance, so recording costs can be reduced from this aspect as well.

Furthermore, when retransferring the ink image on the intermediate transfer medium to the recording medium, no pressure is applied to the recording electrode.
Since sufficient pressure can be applied, ink can be applied even to four parts of the surface of a recording medium with poor surface smoothness.

Hereinafter, the present invention will be described in further detail with reference to the drawings as necessary. In the following description, "%
” and “parts” are based on weight unless otherwise specified.

A typical embodiment of the thermal transfer recording method of the present invention will be described.

The drawing is a schematic cross-sectional view in the thickness direction of a support, showing an embodiment of the present invention when an endless belt-shaped intermediate transfer medium is used. Referring to the drawing, a heat-sensitive transfer material 3 having a layer 2 of heat-melting ink formed on a sheet-like support 1 is transferred from the left to the right in the drawing.

On the other hand, an endless belt-shaped conductive intermediate transfer medium 4 that is disposed below the thermal transfer material 3 (on the ink layer side of the thermal transfer material) that is transported in this manner and continuously moves in the direction of the arrow in the figure is used for recording. The thermal transfer material 3 is brought into contact with the ink layer 2 of the thermal transfer material at a position sandwiched between the electrode 5 and the platen 6, but at this time, the thermal transfer material 3 of the intermediate transfer medium and A patterned voltage is applied to the conductive intermediate transfer medium 4 from the recording electrode 5 in contact with the surface opposite to the surface in contact with the surface, and radio waves are transmitted from the recording electrode 5 to the conductive layer 41 of the intermediate transfer medium and the metallic conductive layer. 42 to the return electrode 7, the conductive layer 41 directly under the recording electrode 5 generates Joule heat in a butter-like manner.

The heat-melting ink that is melted or softened according to this heating pattern is transferred to the intermediate transfer medium 4 and then transferred to the intermediate transfer medium -L.
An ink image 22 is formed on the intermediate transfer medium 4, and as the intermediate transfer medium 4 moves, the ink image 22 is also transferred downward in the figure.

For the intermediate transfer medium 4-, various intermediate processing can be performed on the ink image 22 as required.
By contacting the ink image 22 above, the ink image 2
2 removal or partial removal (correction) is performed.

Next, the intermediate transfer medium 4 contacts the recording medium 9, which is being transported from the right to the left in the figure, at the position of the pressure roll 8 so that the surface to which the ink image 22 is attached is in contact with the recording medium. However, at this time, pressure is applied between the pressure roll 8 and the pressure roll 10, and the ink image 22 is retransferred onto the recording medium 9.

During this retransfer, the ink image 22 may be reheated if necessary, but in this case, for example, a heating heater (not shown) may be provided inside the pressure roll 8, or an intermediate transfer A heater (not shown) may be provided near the -1- flow side of the pressure roll 8 for the medium 4 .

Further, if necessary, cleaning means such as a blade 11 may be provided on the downstream side of the pressure roll 8 for the intermediate transfer medium 4.

Next, the configuration of each part shown in the drawings will be explained.

As the support 1, any material having any desired quality or shape can be used as long as it has the necessary strength and flexibility. In the thermal transfer recording method of the present invention, Joule heating is generated in the conductive intermediate transfer medium and this heat is directly applied from the ink layer side of the thermal transfer material, so the support does not need to be conductive or heat resistant. Furthermore, the transferability of the ink is not affected by the thickness of the support.

Examples of the support l include cloth such as cotton cloth and nylon cloth, paper such as cellophane paper, capacitor paper, and parchment paper, polyethylene, polypropylene, polyamide, polyester,
Plastic films such as triacetyl cellulose, polycarbonate, and polyvinyl alcohol are preferably used, but the film is not limited to these and can be selected from a wide range of materials. Considering the cost of the thermal transfer material, it is preferable to use a low-cost support.

The thickness of the support l is not particularly limited as described above, but if space is taken into account when storing the thermal transfer material, it may be, for example, about 2 to 10 pm, more preferably 2 to 5 gm.
degree is preferably used.

The heat-melt ink constituting the heat-melt ink layer 2 is made by dispersing or dissolving a coloring agent in a heat-melting binder. As the heat-melting binder, various binders conventionally used as heat-melting binders such as natural or synthetic waxes and resins can be used alone or in combination of two or more.

If a thermofusible binder with supercooling properties (hereinafter referred to as "supercooled thermofusible binder") is used as the thermofusible binder, the thermofusible ink will remain in a molten state for a certain period of time even after the heat application is finished. In order to retain the ink image, there is no need to reheat the ink image when performing various intermediate processing on the ink image 22 on the intermediate transfer medium 4 or when retransferring the ink image 22 from the intermediate transfer medium 4 to the recording medium 9. This is preferable.

Here, supercooled thermofusible binder refers to a binder that, once heated above its melting point (used to include the softening point) and cooled from a molten or softened state, remains constant even at a temperature below its original melting point. Time refers to a binder that maintains a molten or softened state, and is known per se.

Such a binder having supercooling properties includes, for example, a plasticizer such as N-cyclohexyl-P-)toluenesulfonamide, N-ethyl-pH-toluenesulfonamide, dicyclohexyl phthalate, which is a known supercooling substance, or Benzotriazole, acedoyl, etc. or their derivatives can be used singly or in combination of two or more to produce polyamide resins, polyacrylic resins, polyvinyl acetate resins, or their co-containers, which have been used in conventional hot-melt inks. Thermoplastic resins such as polymers (
Preferably, the softening point is 40 to 230°C, more preferably 50 to 200°C by ring and ball method), and can be obtained by mixing it with a heat-melting binder such as various natural or synthetic waxes.

To obtain the supercooled thermofusible binder used in the present invention,
For example, 20 to 90 parts of the above-mentioned supercooled substance may be mixed with 10 to 90 parts of the thermofusible binder described in Section 2.

Additionally, it is also possible to adjust the supercooling property by adding an oil or the like to the supercooled thermofusible binder, or to adjust the melt viscosity, adhesive strength, etc. by adding elastomers to the abovementioned thermofusible binder. It is.

As the coloring agent that composes the heat-melting ink together with the heat-melting binder, all the dyes and pigments commonly used for printing or other recording methods, such as carbon black, are used, and these dyes and pigments can be used alone. Or a mixture of two or more types can be used. The content of the colorant is preferably 1 to 40% based on the ink described in -1-.

To obtain the heat-sensitive transfer material 3 used in the present invention, the above-described heat-melting binder, colorant, and additives are melt-kneaded using a dispersion device such as an attriter, or kneaded with an appropriate solvent and melted. The ink is obtained in the form of a liquid ink, a solution or a dispersion liquid, and then a hot melt coating or solvent coating method is applied to coat the ink to a thickness of 0.5 to 0.5 mm.
The heat-melting ink layer 2 is formed on the support L-L at 10 pLm, preferably from 2 to 6 pLm.

The planar shape of the thermal transfer material 3 used in the present invention is not particularly limited, but generally a typewriter ribbon shape or an 11-wide tape shape used for line printers and the like is preferably used. Furthermore, for color recording, it is also possible to use a heat-sensitive transfer material in which heat-melt inks of several different tones are applied in stripes or blocks.

The conductive intermediate transfer medium 4 is obtained by forming a metallic conductive layer 42 on a conductive sheet constituting the conductive layer 41. The conductive sheet is made of a conventionally known film material,
For example, polyester resin, fluororesin, polycarbonate resin, triacetyl cellulose resin, nylon resin,
Carbon black, titanium black, metal, Sn
It can be easily obtained by dispersing conductive fine particles such as 02 and forming it into a film. The specific resistance of the conductive layer 41 can be adjusted to 10 to 1040 cm, preferably 10 to 1040 cm, by adjusting the content of the conductive fine particles.
is set to

The thickness of the conductive layer 41 is preferably about 2 to 500 ILm, more preferably about 5 to 500 ILm.

A metal P1 conductive layer 42 having higher conductivity than the sheet is provided on the conductive sheet 41. This is to apply a voltage to the conductive sheet 41 wrapped around the recording electrode 5 and the conductive layer 42 to generate Joule heat in a pattern.

The metallic conductive layer is, for example, A1. By bonding a metal foil to the conductive sheet 41 using a metal such as Cu, or by forming a metal thin film on the conductive sheet 1- by a method such as plating or vapor deposition, the thickness is preferably 0.01. ~0.3 m
It is obtained as a thin film of about 100%. On the contrary, metal thin film or foil 4
The conductive layer 41 may be formed on the conductive layer 2 by coating or extrusion lamination.

1- The intermediate transfer medium 4 composed of the conductive layer 41 and the metal conductive layer 42 may be used as an endless belt system as shown in the figure, or may be used repeatedly with other intermediate transfer media. May be used. For example, although not particularly shown, the intermediate transfer medium may have a hollow cylindrical shape, or a system in which the intermediate transfer medium is unwound from a supply roll and wound around a take-up roll is also preferably used.

As the recording electrode 5 for applying a patterned voltage to the conductive intermediate transfer medium 4, for example, the 1-shaped or multi-stylus-shaped electrodes described in JP-A-56-93585, JP-A-1V5B-12790, etc. can be used. is used.

The recording conditions using the recording electrode 5 include an applied pulse of 110
, about 5 to 5 m5ec is preferable. By controlling these recording conditions, it is also possible to record so-called intermediate tones.

As the return electrode 7 that contacts the metallic conductive layer 42 of the intermediate transfer medium 4, an electrode having a shape that can contact the conductive layer 42 without damaging it is used, and for example, a roll-shaped electrode as shown is preferably used.

The platen 6, pressure roll 8 and roll IO are as follows:
Either an elastic roll whose surface is made of nitrile rubber, polyurethane rubber, natural rubber, ethylene propylene rubber, vinyl chloride resin, nylon resin, etc. or a rigid roll whose surface is made of metal, ceramics, etc. can be used. It is.

The pressure applied by the platen 6 is applied at a surface pressure of 0.1 to 2 K g/c in order not to place an excessive pressure burden on the recording electrode 5.
About m' is preferable. In addition, the pressure applied by the pressure roll 8 and the pressure roll 10 is set to a linear pressure of 0.5 to 0.5 so that the hot-melt ink can sufficiently adhere to the four surfaces of the recording medium 9.
Approximately 1 OK g/cm is preferable.

The blade 11 is a member for removing heat-melting ink remaining on the intermediate transfer medium 4-1- without being transferred to the recording medium 9. For example, the blade 11 is a member made of metal, resin, etc. that removes the residual ink by scraping it off. A knife-like or brush-like member made of the like is preferably used.

1; In order to remove the residual ink described in ``2'', instead of the blade 11, a commercially available adhesive tape is brought into contact with the intermediate transfer medium 4, or, in particular, the above-mentioned supercooled thermofusible binder is used. In this case, a commercially available absorbent paper may be brought into contact with the intermediate transfer medium 4 to adhere or absorb the heat-melting ink.

As mentioned above, various intermediate processing means such as addition, removal, and correction of ink images can be applied to the four intermediate transfer media as necessary. Here, as an example of the intermediate processing means, a case where a removal sheet as a means for removing or partially removing an ink image as shown in the drawings is used will be explained in some detail.

The removal sheet 12 is a member that absorbs or adheres to the heat-melting ink constituting the ink image 22 and removes or partially removes the ink image. As the removal sheet 12, a sheet-like material with an adhesive surface that absorbs or adheres to the ink, such as a commercially available adhesive tape, is preferably used. In addition to this, -■- absorbs or absorbs ink. paper, which is a sheet-like porous material;
A porous plastic sheet or the like may also be used.

The removal sheet 12 is brought into contact with the intermediate transfer medium 4 as the roll 13 moves in the left-right direction by a moving means (not shown), and the ink image 22 is absorbed or attracted to the removal sheet 12. and is removed (or partially removed) from the intermediate transfer medium 4. In the intermediate transfer medium 4, the above-mentioned removal (or partial removal) of the ink image is performed.
In addition, additional ink images can be added, and corrections such as bleeding can be made to the ink image 22.

The typical embodiment of the thermal transfer recording method of the present invention has been described above, but instead of the intermediate transfer medium 4 consisting of the conductive sheet 41 and the metallic conductive layer 42, the intermediate transfer medium 4 consisting of only the conductive sheet 41 is used. Medium (not shown)
You can also use

In this case, although not particularly shown in the drawings, as will be explained with reference to the drawings, a large-area return electrode 7 is arranged as the return electrode 7, which has a larger area than the recording electrode 5 and is in contact with the conductive sheet (41). A current is passed through the conductive sheet 41 to the large area return electrode. As a result, the conductive sheet 41 directly under the recording electrode 5 with a large current density generates Joule heat in a pattern, and the ink melted or softened in the pattern of the ink layer 2 in contact with the surface of the intermediate transfer medium 4. The image is transferred to an intermediate transfer medium 4. The other configurations are almost the same as those shown in the drawings.

1-1-As described above, according to the present invention, a voltage is applied to a conductive intermediate transfer medium to cause the intermediate transfer medium itself to generate heat in a pattern, and this heat is transferred to the heat-sensitive transfer material. The ink is supplied directly to the heat-melting ink layer to selectively melt or soften the ink, and the ink is once transferred to the intermediate transfer medium, and then the ink image on the intermediate transfer medium -1- is pressed onto the recording medium. A recording electrode type thermal transfer recording method is provided.

According to the thermal transfer recording method of the present invention, the recording speed is high;
While maintaining the advantage of the recording electrode method of high thermal efficiency,
Since expensive conductive materials are repeatedly used as intermediate transfer media, costs can be significantly reduced. In addition, since heat is applied directly to the heat-melting ink layer of the heat-sensitive transfer material, heat resistance is not required for the support of the heat-sensitive transfer material, which also contributes to a reduction in recording cost 1. It is also possible to directly and delicately control the conditions to adjust the transfer amount of the heat-melting ink and obtain so-called half-tone recording.

Furthermore, when retransferring the ink image from the intermediate transfer medium to the recording medium, pressure can be applied without putting a burden on the recording electrode, so ink can be attached to all four parts of the surface of the recording medium by controlling the applied pressure. This makes it possible to obtain good printing even on recording media with poor surface smoothness.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

``Electric charger'' A hot-melt ink was prepared according to the following recipe.

Carbon black 10 parts MA-11
(manufactured by Mitsubishi Kasei Corporation) Montan wax 20 parts (manufactured by Hoechst Wax Company) Low molecular weight oxidized polyethylene 10 parts (manufactured by Allied Chemical Company) Paraffin wax 60 parts (manufactured by Hiki Seiro Co., Ltd.) Each of the components shown above was sand milled. The mixture was mixed and stirred to obtain a hot-melt ink. This ink was coated using a wire bar on one side of a polyethylene film 15ILm thick, and a 5IL thick film made of a heat-melting ink with a melting point of 70°C was coated with a polyethylene film 15ILm thick.
A thermal transfer material 3 having an ink layer 2 of Lm was obtained. This thermal transfer material 3 was installed in the apparatus shown in the drawings, and a printing test was conducted as follows.

In the above-mentioned apparatus, the conductive intermediate transfer medium 4 is made by dispersing carbon black in polycarbonate resin and has a specific resistance of 100Ω cm. A as the conductive layer 42
I was vacuum-deposited to a thickness of 0.17 mm to form an endless belt.

Next, the recording electrode 5 (applied pulse 111: 0, 7
conductive layer 41 of intermediate transfer medium 4 using
A voltage according to a desired pattern was applied from the side, and the softened hot melt +1 ink was transferred in a pattern onto the metallic conductive layer 42''. Furthermore, the ink transferred to the intermediate transfer medium 41- is transferred to pound paper with a smoothness of 3 to 4 seconds by an Oken type smoothness meter, using a pressure roll 8 and a pressure roll IO to apply a linear pressure of 5 seconds.
Transfer was performed while applying a pressure of K g/cm. At this time, the pressure roll 10 was heated to maintain its surface temperature at 80° C. to completely transfer the ink.

The recorded image transferred to the low 41 smoothness pound paper described in 1-1 was good at 11 viewing in terms of print quality such as print density, transferability, clarity, etc., and the smoothness was 120 by the same method as in Almost the same print quality as when transferred to high-quality paper was obtained in seconds.

At this time, by changing the pulse width applied to the recording electrode, the transfer density of the heat-melting ink to the recording medium 9 is changed,
A halftone recorded image was obtained on the recording medium.

Carbon black 10 parts Printyx L (manufactured by Degussa) Polyamide resin 60 parts Susumide #55 (manufactured by Sansho Kagaku) N-ethyl-P-)luene 40 parts Sulfonamide ethyl acetate 300 parts As shown in the above recipe Each component was mixed to obtain a coating liquid of heat-melting ink having supercooling properties. This coating solution was coated on the same support as in Example 1 and dried to obtain a thermal transfer material 3 having a layer (thickness: 5 gm) of heat-recording and melting ink having a melting point of 62°C.

Using this heat-sensitive transfer material, a printing test was conducted in the same manner as in Example 1 except that the pressure roll 10 was not heated.

In this example, since a heat-melting ink having supercooling properties was used, the pressure roll lO was not heated, and the
A recorded image of comparable good print quality was obtained on pound paper.

Further, by changing the width of the pulse applied to the recording electrode, a half-tone recorded image was obtained as in Example 1.

[Brief explanation of drawings]

The drawing is a schematic cross-sectional view in the thickness direction of a support, showing an embodiment of the present invention when an endless belt-shaped intermediate transfer medium is used. l...Support 2...Thermofusible ink layer 22...Transferred ink image 3...Thermal transfer material 4...Conductive intermediate transfer medium 41...Conductive layer 42... Metallic conductive layer 5...recording electrode 6...platen 7...return electrode 8...pressure roll 9...recording medium lO...pressure roll 11...blade 12... Removal sheet 13...removal roll

Claims (1)

[Claims] The ink layer side of a heat-sensitive transfer material comprising a layer of heat-melting ink provided on a support is brought into contact with one surface of a conductive intermediate transfer medium, and the side of the intermediate transfer medium opposite to the surface in contact with the heat-sensitive transfer material selectively transferring the hot-melt ink to the intermediate transfer medium by applying a patterned voltage to the surface of the intermediate transfer medium; A thermal transfer recording method comprising the step of transferring an ink image to a recording medium under pressure.