JPH0542779A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To obtain a good gradation image due to dyeing even on an image receiving material having no dyeing layer. CONSTITUTION:A thermal transfer sheet 1 is formed by laminating a dye- containing ink layer 3 to a heat-resistant sheet like support 2 and further laminating a softenable transfer layer 4 composed of a softenable transfer material lowered in its viscosity by heating and fixing the dye in the ink layer 3 to the ink layer 3. At first, when the thermal transfer sheet 1 is heated while pressed to an image receiving material at the time of recording, the dye in the heated ink layer 3 is diffused to the softenable transfer layer 4 softened under heating. Therefore, a part of the dyed softenable transfer material is transferred to the image receiving layer to form a recording image. Since the dye contained in the softenable transfer material is proportional to heating quantity, continuous gradation recording can be performed by controlling heating quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer sheet capable of obtaining a continuous tone image with a dye even when an image receptor having no dyeing layer is used.

[0002]

2. Description of the Related Art In recent years, a sublimation type thermal transfer using an ink sheet having an ink layer containing a sublimable dye and an image receptor having a dyeing layer for receiving the dye sublimated by thermal printing from the back surface of the ink sheet. The recording system is capable of excellent halftone recording and has been attracting attention as one that provides full-color image recording.

For example, FIG. 3 shows a schematic configuration diagram of a sublimation type thermal transfer recording apparatus in a conventional embodiment. In FIG. 3, 100 is a heat-resistant sheet-shaped substrate. Reference numeral 101 is an ink layer composed of a dye and a binder material, 102 is an ink sheet in which the ink layer 101 is formed on the surface of a sheet-shaped substrate 100, 103 is a substrate, and 104 is a dye that strongly adheres to the dye contained in the ink layer 101. A dyeing layer, 105 is an image receptor in which the dyeing layer 104 is formed on the substrate 103, and 106 is the heating element 10.
Thermal head having 7, 108 is thermal head 1
06 is a platen that presses the ink sheet 102 and the image receiver 105 into pressure contact with each other.

The operation of the thermal transfer recording apparatus configured as described above will be described below. The ink layer 101 of the ink sheet 102 and the dyeing layer 1 of the image receiver 105
04 is pressed between the thermal head 106 and the platen 108 to heat the heating element 107 of the thermal head 106 in response to a signal from a recording signal source (not shown) to generate the ink heating unit 109. At this time, the dye is transferred from the ink layer 101 into the dyeing layer 104 according to the heating amount. After that, the image receptor 10 is rotated by the rotation U of the platen 108.
5, the ink sheet 102 is fed in the direction of arrow V, the ink sheet 102 is fed in the direction of arrow W, the ink sheet 102 is peeled from the image receiving body 105, and the transferred dye image 1 is transferred to the dyeing layer 104 by the transferred dye.
Get 13.

Conventionally, an ink sheet 102 using a sublimable dye as a coloring material is, for example, 10 parts by weight of polyvinyl butyral as a binder material on the surface of a sheet substrate 100 such as a polyethylene terephthalate (PET) film having a thickness of about 9 μm. An ink layer 101 composed of 6 parts by weight of the sublimation disperse dye was formed by a solvent coating method. The image receiving body 105 has a dyeing layer 104 made of polyester resin or the like formed on the surface of the substrate 103 made of polyester or high-quality paper.

Using these ink sheet and image receptor, as shown in FIG. 3, the dye contained in the ink layer is dyed and transferred to the dyeing layer on the surface of the recording paper to obtain a recorded matter, as shown in FIG. Thermal transfer recording devices are also known (for example, Eye Transaction on Consumer Electronics, Vol.CE-28, No.3, pp.226-231, August 198).
2).

[0007]

However, in the above-mentioned constitution, in order to utilize the dyeing action of the dye, a dyeing layer is required on the image receptor, and dyeing such as commonly used pulp paper is required. There is a problem that recording cannot be performed on an image receptor having no layer.

In view of the above-mentioned problems, the present invention provides a thermal transfer sheet which provides a high quality gradation image by dyeing a dye even on an image receptor having no dyeing layer.

[0009]

In order to solve the above-mentioned problems, the thermal transfer sheet of the present invention comprises an ink layer containing a dye on a heat-resistant sheet-like substrate, and the viscosity decreases when the temperature rises. A softening transfer layer made of a softening transfer material dyed with the dye is laminated.

[0010]

The thermal transfer recording using the thermal transfer sheet of the present invention described above is performed in the same manner as the conventional thermal transfer recording. First,
The ink layer is heated by heating from the side of the sheet substrate while pressing the thermal transfer sheet against the image receiver. At this time, the softening transfer material is dyed with the dye of the ink layer according to the amount of heating, and the viscosity of the softening transfer material is lowered in the heating portion. That is, due to the decrease in viscosity, at least a part of the dyed softening transfer material is transferred to the image receiver. Therefore, a good gradation image can be obtained by the dye even on the image receptor having no dyeing layer.

Particularly, the difference from the conventional example is that the difference between the dyeing portion on the same surface laminated on the ink layer and on the image receiving side of the other surface is very different. Further, in the present invention, the softening transfer material is transferred only to the heated portion, and the softening transfer material is hardly transferred to a portion without a recorded image. No, the writing performance is also good.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a partial cross sectional view of a thermal transfer sheet according to an embodiment of the present invention. In FIG. 1, 1 is a thermal transfer sheet comprising a sheet-shaped substrate, an ink layer, and a softened transfer member, 2 is a heat-resistant sheet-shaped substrate, 3 is an ink layer containing a dye, and 4 is viscosity reduced by heating, It is a softening transfer layer made of a softening transfer material that is dyed with the dye in the ink layer 3.

The procedure of thermal transfer recording using this thermal transfer sheet 1 is shown in FIG. First, while the thermal transfer sheet 1 is pressed against the image receiving body 5 by the thermal head 6, the amount of electricity supplied to the heating element 7 of the thermal head 6 is controlled by the signal source 8. Then, the heated dye in the ink layer 3 diffuses into the softening transfer layer 4, and the softening transfer layer 4 is softened. Due to this softening, an adhesive force or a penetrating force to the image receptor 5 is generated in the softened transfer material, and at least a part of the dyed softened transfer material is transferred to the image receptor 5 to form a recorded image 9. Since the dye contained in the transferred softening transfer material is proportional to the heating amount, continuous tone recording can be performed by controlling the heating amount. The softening by heating shown in the present invention means that the softening material is heated to a softening point or a melting point or higher.

As described above, according to this embodiment, by using the thermal transfer sheet in which the viscosity is lowered by heating and the softened transfer layer 4 made of the softened transfer material dyed with the dye is formed on the ink layer. , The image receptor 5 without the dyeing layer,
By dyeing, an image can be recorded with good gradation. Further, since the softened transfer material is hardly transferred to the unheated portion, the texture of the image receptor 5 is not lost, and the writing property is similar to that of the image receptor 5.

The softening point or melting point of the softening transfer material is
It is preferable to select the same as or lower than the dyeing temperature of the dye. This is because if the softening point or melting point is considerably higher than the dyeing temperature, the dye density will be high at the time when the softening transfer material is transferred, and it will not be possible to reproduce low density recording satisfactorily. This is because the key record cannot be recorded.

The sheet-like substrate 2 is made of, for example, a heat-resistant resin film such as polyethylene terephthalate or polyimide,
Alternatively, capacitor paper or the like can be used. In addition, it is also possible to use one having a heat resistant film made of silicone or the like formed on the surface on which the ink layer 3 is not formed.

The ink layer 3 is composed of a dye that thermally diffuses when heated and a binder material. As this dye, various dyes having a dyeing property such as a water-soluble dye, an oily dye, a dispersible dye and a sublimable dye are used. it can. When a black type is used, a black and white image is added, and cyan, yellow, magenta, and further black are added, and these are sequentially overlapped and recorded so that a full color image can be thermally transferred and recorded. The binder material can be composed of a single resin or a mixture of resins such as polyester, vinyl chloride resin, vinyl chloride / vinyl acetate copolymer resin, acrylic resin, nylon resin, silicone resin, butyral resin, and the like.

The softening transfer layer 4 is composed of a softening transfer material whose viscosity is lowered at the time of temperature rise and which is dyed with a dye. This softening transfer material contains a thermoplastic resin and a wax that are dyeable, and include, for example, waxes such as polyethylene glycol, paraffin, carnauba wax, and polyethylene wax that are solid at room temperature, polyvinyl butyral, and polyethylene oxide. Resins such as ethyl cellulose and polyester may be used alone or in combination. In addition, for softening transfer materials, surfactants such as polyoxyethylene nonyl phenyl ether, sorbitan monostearate, polyoxyethylene lanolin alcohol ether, dibutyl phthalate, Plasticizers such as dicyclohexyl acid and liquid paraffin, and fine particles such as calcium carbonate and talc can also be mixed.

In order to improve the transferability to the image receptor 5, the softened transfer material is required to have a viscosity lowered by heating and to be adhered or penetrated into the image receptor 5. Further, in order to clearly distinguish transfer and non-transfer of the softened transfer material at the boundary between the adjacent heating part and non-heating part, it is preferable to use a material whose viscosity is greatly reduced by heating, that is, a material having a melting point, for example, It is recommended to use waxes such as polyethylene glycol and paraffin that are solid at room temperature.

Further, when the viscosity of the softened transfer material is lowered during heating and becomes liquid, the softened transfer material behaves as a solvent to dissolve the dye. Therefore, even if the dyeing power of the dye is small, it is possible to impregnate the dye into the softening transfer material by this dissolution phenomenon.

When the softening transfer material is heated, the ink layer 3
A material having a low compatibility with the binder material forming the ink layer 3 is preferable so as not to be adhered to, and a water-soluble material such as polyethylene glycol or polyethylene oxide, a paraffin having a low compatibility, or a wax such as carnauba wax is preferable. In particular, when waxes are used, a recorded material having high water resistance can be obtained.

The thermal transfer sheet 1 is prepared, for example, by first applying a solution obtained by dissolving or dispersing a dye in a solution in which a binder material is dissolved onto a sheet-like substrate 2 by a solvent coating method, drying the solution, and then dissolving the ink layer 3. It is obtained by forming a softened transfer layer 4 by applying a solution in which a softened transfer material is dissolved or dispersed in a solvent which is not applied onto the ink layer 3 and drying it.

As the solvent used when forming the ink layer 3 or the softening transfer layer 4, for example, water, alcohol,
Various organic solvents such as octane, acetone and toluene can be used alone or in combination. However, since the ink layer 3 is formed of a lipophilic material in most cases, water is most preferable as the solvent used when forming the softening transfer layer 4. Therefore, in the case of a water-insoluble softening transfer material, a coating liquid (dispersion) in which the softening transfer material is dispersed is used in terms of safety, environmental pollution, performance and cost.

As the image receptor 5, synthetic paper, art paper, coated paper, high-quality paper, baryta paper, cellulose fiber paper, plastic film and the like are preferably used alone or as a laminate thereof.

The following are experimental examples of various thermal transfer sheets that have been trial-produced. The sheet-shaped substrate 2 is made of polyethylene terephthalate having a thickness of 6 μm and a butyral resin (Sekisui Chemical Co., Ltd.).
20 parts and indoaniline cyan dye (Mitsubishi Kasei)
10 parts of toluene / ethanol 1/1 solvent 7
What was dissolved in 0 part was applied and dried to form an ink layer having a thickness of about 5 μm. This thermal transfer sheet was used as a conventional thermal transfer sheet.

Further, polyethylene glycol (melting point 60 ° C., Daiichi Kogyo Seiyaku Co., Ltd.) solid at room temperature is formed on the ink layer 3.
(Made by Asahi Glass Co., Ltd.), 80 parts of water, and 0.2 part of a fluorine-containing surfactant (made by Asahi Glass Co., Ltd.) are applied and dried to form a softened transfer layer 4 having a thickness of about 5 μm. It was formed into a first thermal transfer sheet 1 according to the present invention.

Further, after rubbing paraffin wax (melting point is 57 ° C.) on the above-mentioned ink layer 3, a softened transfer layer 4 is formed by hot air to form a coating film having a thickness of about 10 μm. The second thermal transfer sheet 1 was used.

Further, on the above-mentioned ink layer 3, 5 parts of polyethylene oxide (softening point is 67 ° C., manufactured by Steel Chemical Industry Co., Ltd.) solid at room temperature, 95 parts of water, and a fluorine-containing surfactant ( Asahi Glass Co., Ltd.) (0.2 parts) was applied and dried to form a softened transfer layer 4 having a thickness of about 4 μm, which was used as a third thermal transfer sheet 1 according to the present invention.

These three sheets are heated and recorded (up to 9 J / c at maximum by a pulse width control signal while pressing against high quality paper by a thermal head 6 having a recording density of 6 dots / mm.
m ² ), a conventional thermal transfer sheet produced a faint recorded image with an optical reflection density of 0.2 or less.
In the first, second, and third thermal transfer sheets 1 on which the softened transfer layer 4 is formed, the gradation recording images of cyan single color with the maximum densities of 1.7, 1.3, and 1.4 rise smoothly from the paper surface density. I was able to get

However, when the second thermal transfer sheet 1 was used, the dyeing power of paraffin to the dye was low, so that the color was not vivid and the density was slightly low. In addition, in the third thermal transfer sheet, since the viscosity of polyethylene oxide is not drastically decreased, the break of the image is poor, and
There was a region where the extra softening transfer material was transferred. But,
No matter which thermal transfer sheet 1 was used, the softening transfer material was hardly transferred to a place where there was no recorded image, and the writing performance was good.

Although the single-color recording is described in this embodiment, a full-color image can be easily obtained by performing the overlapping recording.

After the image is recorded, the entire surface of the recorded image may be heated to improve the fixing property of the image.

Further, a peeling layer made of a silicone resin or the like can be formed between the ink layer and the softening transfer layer so that the softening transfer material can be easily transferred.

[0035]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, by forming a softening transfer layer composed of a softening transfer material which is dyed with a dye and has a reduced viscosity upon heating, on the ink layer containing the dye, A good gradation recording image can be obtained even for an image receptor having no layer.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a thermal transfer sheet according to an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of thermal transfer recording for explaining the operation in the embodiment.

FIG. 3 is a block diagram of a conventional example

[Explanation of symbols]

 1 Thermal Transfer Sheet 2 Sheet-like Substrate 3 Ink Layer 4 Softening Transfer Layer 5 Image Receptor 6 Thermal Head 7 Heating Element 8 Signal Source 9 Recorded Image

Claims (2)

[Claims] 1. A heat-resistant sheet-like substrate, on which an ink layer containing a dye and a softening transfer layer made of a softening transfer material which is dyed with the dye when the viscosity of the ink is lowered when the temperature is raised are laminated. A thermal transfer sheet characterized by. 2. The thermal transfer sheet according to claim 1, wherein the softened transfer material has a steep drop in melting point.