JPH0421600B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal transfer sheet, and more particularly to a thermal transfer sheet used in combination with a thermal transfer sheet on which thermal printing is performed according to image information using a thermal head or laser.

Conventionally, thermosensitive coloring paper has been mainly used to obtain images according to image information using a thermal head or laser. In this heat-sensitive coloring paper, a colorless or light-colored leuco dye provided on a base paper and a color developer are brought into contact with each other by heating to obtain a colored image. As such color developers, phenolic compounds, zinc salicylate derivatives, rosin, etc. are generally used. However, heat-sensitive color paper as described above has the fatal drawback that the color image will fade if stored for a long period of time, and color printing is limited to two colors and has continuous gradation. It was not possible to obtain a color image.

On the other hand, thermal transfer paper in which a heat-fusible wax layer in which pigments are dispersed is provided on a base paper has recently begun to be used. When this thermal transfer and transfer paper are superimposed and thermal printing is performed from the back side of the heat-sensitive transfer paper, the wax layer containing the pigment is transferred onto the transfer paper to obtain an image. According to this printing method,
Durable images can be obtained, and multicolor images can be obtained by printing multiple times using thermal transfer paper containing pigments in the three primary colors, but photographs with essentially continuous gradations cannot be used. It is not possible to obtain such an image.

Incidentally, in recent years, there has been an increasing demand for obtaining photograph-like images directly from electrical signals, and various attempts have been made. One such attempt is a CRT
This method involves projecting an image on top and photographing it using silver halide film, but if the silver halide film is an instant film, the running cost increases, and if the silver halide film is 35mm film, has the disadvantage that it is not instantaneous because it requires development processing after photographing. As other methods, the impact ribbon method and the inkjet method have been proposed, but the former has the disadvantage of poor image quality, and the latter requires image processing, making it difficult to easily obtain photographic images. There is a drawback.

In order to solve these drawbacks, a thermal transfer sheet provided with a sublimable disperse dye layer that transfers when heated is used in combination with a thermal transfer sheet, and the sublimable disperse dye is controlled and transferred onto the thermal transfer sheet. A method has been proposed to obtain a photo-like image with gradation by shifting the image to . This method is attracting attention because an image having continuous gradation can be obtained from a television signal through simple processing, and the equipment used therein is not complicated. One of the conventional techniques similar to this method is the dry transfer printing method for polyester fibers, which involves dispersing or dissolving dyes such as sublimable disperse dyes in a synthetic resin solution. This paint is applied in a pattern onto tissue paper, etc. and dried to form a heat transfer sheet.This heat transfer sheet is placed on polyester fibers, which are the heat transfer sheet, and heated in close contact to dye the polyester fibers with disperse dyes. This is a method of obtaining images by

However, when a thermal transfer sheet as described above and a thermal transfer sheet made of polyester fiber are overlapped,
Even if this is heated and printed using a thermal head or the like, a high-density colored image cannot be obtained. One of the reasons for this is that the surface smoothness of the polyester fiber cloth is not good, but it is believed that this is mainly due to the following reasons. In other words, in the normal dry transfer printing method or wet transfer printing method,
The migration of sublimable dyes onto polyester fiber fabrics is
Although the heating time is sufficient,
This is because the heating with a thermal head or the like is usually very short, so that the dye does not transfer sufficiently onto the fabric. By the way, in the dry transfer printing method,
Dye transfer is achieved by heating at 200°C for about 1 minute, whereas heating with a thermal head is as short as several ^milliseconds at 400°C.

The present inventors conducted research aimed at solving the above-mentioned drawbacks mainly by improving the thermal transfer sheet, and as a result, discovered the following facts.

When clay-coated paper or synthetic paper is used as a thermal transfer sheet, there is a drawback that it cannot sufficiently receive the dye transferred from the thermal transfer sheet, and therefore a colored image with high density cannot be obtained.

On the other hand, when a thermal transfer sheet having a low melting point synthetic resin as a receptor layer is used, the synthetic resin layer itself becomes thermally adhesive due to the action of heat and pressure applied to the thermal transfer sheet. may be transferred onto the thermal transfer sheet, which has the disadvantage that the clarity and resolution of the resulting image are not impaired.

Furthermore, when using a thermal transfer sheet having a synthetic resin with a low glass transition temperature as the receptor layer, the dye thermally transferred onto the thermal transfer sheet is sufficiently fixed and a high-density colored image can be temporarily obtained, but it takes time. It was also found that the dye was thermally diffused and the image was distorted. On the other hand, it has been found that when the receiving layer of the thermal transfer sheet is made of a synthetic resin having a high glass transition temperature, the above-mentioned thermal diffusion can be prevented, but the fixability of the dye transferred from the thermal transfer sheet is poor. As an extreme example, if a soft polyvinyl chloride resin sheet containing an ester group-containing plasticizer, such as dioctyl phthalate, is used as the receiving layer of a thermal transfer sheet, a high-density, excellent color image will be produced immediately after thermal transfer. However, because the dye dissolves in the plasticizer and diffuses into the sheet, the colored image obtained becomes extremely unclear if it is left at room temperature for about a week, making it virtually impossible to preserve the colored image. It turns out it's possible.

The present invention aims to solve the drawbacks associated with the prior art, and aims to achieve the following objects by using a thermal transfer sheet having a specific structure.

(a) Obtaining a colored image with continuous gradations like a photograph directly from electrical signals.

(b) To obtain a colored image with high density and high transparency, and to obtain a clear, high-resolution image that does not fade even after being stored for a long period of time.

(c) To provide a thermal transfer sheet in which the thermal transfer layer does not peel off and transfer to the thermal transfer layer and the thermal transfer sheet and the thermal transfer sheet do not fuse together during thermal transfer.

(d) To obtain high-quality images with excellent dot shape reproducibility of the thermal head.

In order to achieve the above objects, the present inventors conducted extensive research and found that a thermal transfer sheet having a specific structure can achieve the above objects, leading to the present invention.

That is, the present invention provides a thermal transfer sheet having a receptor layer that receives dyes transferred from the thermal transfer sheet when heated, wherein the receptor layer is mainly composed of a crosslinked product of polyurethane polyol and polyisocyanate. The subject matter is a thermal transfer sheet characterized by the following.

Hereinafter, preferred specific examples of the present invention shown in the drawings will be described.

The thermal transfer sheet 1 according to the present invention is constructed by providing a receptor layer 3 on a base material 2 as shown in FIG. 1, but as shown in FIG. 1 may be configured. When the receptive layer 3 is provided on the base material 2, the thickness of the receptive layer 3 is 3
~50 μm, preferably about 5 to 15 μm. On the other hand, when the thermal transfer sheet 1 is composed of the receptor layer 3 alone, the thickness of the receptor layer 3 is about 60 to 200 μm, preferably about 90 to 150 μm.

Materials for the base material 2 include art paper, coated paper,
Examples include papers such as high-quality paper, cast-coated paper, and synthetic paper, and plastic films such as polyethylene terephthalate and polypropylene.

The receptor layer 3 in the present invention is formed mainly of a crosslinked product of polyurethane polyol and polyisocyanate.

In the present invention, the crosslinked product of polyurethane polyol and polyisocyanate forming the receiving layer 3 has a glass transition temperature of -100 to 20°C.

If the glass transition temperature of the crosslinked product forming the receptor layer 3 is less than -100°C, there is a drawback that the image tends to become blurred over time, and if it exceeds 20°C, there is a drawback that the recording density tends to decrease. be.

In the present invention, the blending ratio of polyurethane polyol and polyisocyanate in the crosslinked product forming the receptor layer 3 is determined by
It is determined by the ratio between the NCO content and the OH content in the polyurethane polyol (NCO/OH), and in the present invention, the ratio is 0.5 to 3.5, preferably 1 to 3.

If the above NCO/OH ratio is less than 0.5, problems such as lack of storage stability will occur. That is, when an accelerated storage test is performed in an oven at 60° C., a problem arises in that the dye transferred from the thermal transfer sheet blurs the image in the receiving layer 3.

Furthermore, if the NCO/OH ratio exceeds 3.5, there is a problem in that it is necessary to increase the heating temperature or increase the heating time in order to maintain a constant temperature for the dye transferred from the thermal transfer sheet to the receptor layer 3. occurs.

In forming the thermal transfer sheet 1 of the present invention, for example, a polyurethane polyol, a polyisocyanate, and an additive are dissolved in a solvent to crosslink the polyisocyanate of the polyurethane polyol, and then applied onto the base material 2. The thermal transfer sheet 1 is obtained by heating to evaporate the solvent.

In the present invention, examples of the polyurethane polyol used in forming the crosslinked product include Takerak E-550, Takerak XE-916, Takerak XE-8, Takerak ), desmofen
D80, Desmofene D81 (Sumitomo Bayer Urethane)
Co., Ltd.), etc.

Examples of polyisocyanates include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, xylene diisocyanate, lysine diisocyanate, triisocyanate, etc. Various isocyanate derivatives can be used, such as Takenate D110N, Takenate E-40, Takenate D103H (Takeda Pharmaceutical Co., Ltd.)
(Manufactured by Sumideur Co., Ltd.), Sumideur L, Sumideur IL, Desmodyur N3200, Desmodyur E3260 (manufactured by Sumitomo Bayer Urethane Co., Ltd.), Coronate HL, Coronate N, Coronate L (manufactured by Nippon Polyurethane Co., Ltd.)
etc.

In addition, the above-mentioned additives should be selected from those that do not interfere with the fixation of the dye that migrates from the thermal transfer sheet during heating, and such additives should be selected from those that do not interfere with the fixation of the dye that migrates from the thermal transfer sheet during heating. Examples of the enhancer include cured products of silicone compounds, such as cured products of epoxy-modified silicone oil and amino-modified silicone oil.

Further, an ultraviolet absorber can be used as an additive to prevent color fading of a colored image due to light.

Furthermore, an amino-based or tin-based catalyst may be added to promote the crosslinking reaction between the polyurethane polyol and the polyisocyanate.

The thermal transfer sheet 1 as described above is used in combination with a thermal transfer sheet. A typical thermal transfer sheet 4 has a support 5 as shown in FIG.
A thermal transfer layer 6 is provided on one side of the thermal transfer layer 6, and when the thermal transfer layer 6 is heated, the dye or pigment contained therein is transferred onto the thermal transfer sheet 1.

The support 5 has the role of holding the thermal transfer layer 6, and since heat is applied during thermal transfer, it is desirable that the support 5 has a mechanical strength that does not cause any trouble in handling even when heated. Moreover, in many cases, thermal energy for thermal transfer is applied from the side of the support 5 on which the thermal transfer layer 6 is not provided, so it is desirable that the support 5 also has the property of easily transmitting thermal energy.

Specific examples of the support 5 include flexible thin sheets such as condenser paper, glassine paper, parchment paper, high-size paper, and plastic film. Among these, condenser paper and polyethylene terephthalate film are often used.Condenser paper is mainly used when heat resistance is important, and polyethylene terephthalate film is used when emphasis is placed on preventing breakage during handling with mechanical devices. Mainly used. The thickness of this support 5 is usually 3 to 50 μm, preferably 5 to 15 μm.
That's about it.

The thermal transfer layer 6 contains a coloring material that can escape from the thermal transfer layer 6 and transfer to the receptor layer 3 of the thermal transfer sheet 1 when heated.

Such coloring materials include disperse dyes, oil dyes, certain basic dyes, and intermediates that can be converted into these dyes, which have a relatively small molecular weight of about 150 to 400. From among them, thermal transfer temperature, thermal transfer efficiency, hue, color rendering,
They are selected and used in consideration of weather resistance, etc.

The above coloring material is dispersed in a suitable synthetic resin binder forming the thermal transfer layer 6 and provided on the support 5. As such a synthetic resin binder, it is usually preferable to select one that has high heat resistance and does not hinder the migration of the coloring material that occurs when heated; for example, the following are used.

() Cellulose resins Ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose acetate butyrate, etc.

() Vinyl resin polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinylpyrrolidone,
polyester, polyacrylamide, etc.

Among the above synthetic resin binders, polyvinyl butyral resin or cellulose resin is preferred from the viewpoint of heat resistance.

To provide the thermal transfer layer 6 on the support 5, a coloring material and a synthetic resin binder are kneaded with a solvent or a diluent to form a coating composition for the thermal transfer layer, and this is applied onto the support 5 by an appropriate printing or coating method. It is sufficient to set it in Note that optional additives may be added to the coating composition for the thermal transfer layer, if necessary.

The basic structure of the thermal transfer sheet 4 is as described above, but when the surface of the support is directly heated by a contact heating means such as a thermal head, the thermal transfer layer of the support 5 is not provided. By providing a slippery layer containing a lubricant such as wax or a release agent on the non-stick side, it is possible to prevent the heating means such as a thermal head from fusing with the support and to improve sliding.

The thermal transfer sheet 4 may be in the form of a single sheet cut into required dimensions, may be continuous or wound, or may be in the form of a narrow tape.

When providing the thermal transfer layer 6 on the support 5, a coating composition for the thermal transfer layer containing the same coloring material may be applied to the entire surface of the support 5, but in some cases, a different coloring material may be applied. A plurality of thermal transfer layer coating compositions each containing a coloring material may be formed on different areas of the surface of the support 5, respectively. For example, a thermal transfer sheet in which a thermal transfer layer of different colors and a thermal transfer layer of red are laminated in parallel on the support 5, or a thermal transfer layer of yellow, a red thermal transfer layer, a blue thermal transfer layer, and a black thermal transfer layer are repeatedly layered on the support. A thermal transfer sheet prepared by the manufacturer is used. By using such a thermal transfer sheet provided with a plurality of thermal transfer layers having different hues, there is an advantage that a multicolor image can be obtained with one thermal transfer sheet.

It should be noted that it is also possible to improve the ease of use by forming perforations on the thermal transfer sheet or providing register marks for detecting the positions of areas with different hues.

The thermal transfer sheet 4 and the thermal transfer sheet 1 prepared as described above are stacked facing each other so that the thermal transfer layer 6 of the thermal transfer sheet 4 and the receiving layer 3 of the thermal transfer sheet 1 are in contact with each other, as shown in FIG. By applying thermal energy according to image information to the interface between the thermal transfer layer 6 and the receptor layer 3, the coloring material in the thermal transfer layer 6 is transferred to the receptor layer 3.

In addition to thermal heads, heat sources that provide thermal energy include laser light, infrared flash,
A known device such as a thermal pen can be used. Thermal energy can be applied from the thermal transfer sheet 4 side, from the thermal transfer sheet 1 side, or from both sides, but from the viewpoint of effective use of thermal energy, from the thermal transfer sheet 4 side. It's good to do it. However, it is better to apply thermal energy from the thermal transfer sheet 1 side to control the applied thermal energy and express the gradation of light and shade of the image.
Alternatively, it is preferable in the sense that it promotes the diffusion of the coloring material on the thermal transfer sheet 1 to further ensure the continuous gradation expression of the image, and in the case of a method of applying thermal energy from both sides, there are advantages of both of the above methods. can be enjoyed at the same time.

When a thermal head is used as a heat source for providing thermal energy, the applied thermal energy can be varied continuously or in multiple stages by modulating the voltage or pulse width applied to the thermal head.

When a laser beam is used as a heat source for providing thermal energy, the amount of thermal energy provided can be changed by changing the amount of laser light or the irradiation area. If a dot generator with a built-in acousto-optic element is used, thermal energy can be applied depending on the size of the halftone dot. When using a laser beam, it is recommended that the thermal transfer sheet 4 and the thermal transfer sheet 1 be brought into close contact with each other, and the surface to be irradiated with the laser beam should be colored, for example, black to improve the absorption of the laser beam. It's a good idea to leave it there.

When using an infrared flash lamp as a heat source for providing thermal energy, it is best to use a colored layer such as black, similar to when using laser light, or a pattern that continuously expresses the shading of the image, such as black. Alternatively, it may be done through these patterns using halftone dot patterns,
Alternatively, a colored layer such as black on one side and a negative pattern corresponding to the negative of the pattern described above may be combined.

When thermal energy is applied to the interface between the thermal transfer layer 6 and the receptor layer 3 as described above, a certain amount of the coloring material in the thermal transfer layer 6 is vaporized or melted depending on the applied thermal energy, and the coloring material in the thermal transfer layer 6 is vaporized or melted. The heat is transferred to and accepted.

With the above thermal transfer recording, a coloring material corresponding to the thermal energy is thermally transferred to the receiving layer, and a one-color image can be recorded. And by sequentially replacing the black thermal transfer sheet as necessary and performing thermal transfer according to each color,
It is also possible to obtain a color photo-like color image consisting of a combination of colors. In addition, instead of using the thermal transfer sheet 4 of each color in this way, a thermal transfer sheet 4 having areas formed by painting each color in advance is used.
, first thermally transfer a yellow color image using the yellow area, then thermally transfer the yellow color image using the red area of the thermal transfer sheet 4, and then repeat sequentially to transfer yellow, red, indigo, and as necessary. Adopting a method of thermally transferring a black color separation image has the advantage that there is no need to replace the thermal transfer sheet.

Note that the quality of the image obtained can be improved by appropriately adjusting the size of the heat source used to apply thermal energy, the adhesion between the thermal transfer sheet 4 and the thermal transfer sheet 1, and the thermal energy.

The thermal transfer sheet 1 according to the present invention can be used in combination with the thermal transfer sheet 4 to print using various thermal printing printers, to print by facsimile, or to create photo prints by magnetic recording.
It can be used to create prints from the television screen.

For example, a received television screen may be stored on a storage medium such as a magnetic tape or magnetic disk.
The signal of each color separation pattern of yellow, red, indigo, and black if necessary is stored, and the signal of each stored color separation pattern is output, and the thermal energy corresponding to this signal is transferred to a thermal head, etc. By applying heat to the stacked body of the thermal transfer sheet 4 and the thermal transfer sheet 1 using the heat source described above and performing thermal transfer for each color sequentially, the television screen can be reproduced as a sheet-like print. When the combination of the thermal transfer sheet 1 and the thermal transfer sheet 4 according to the present invention is used to print out such a television screen, the defendant thermal transfer sheet is usually the white receptor layer 3 alone, or It is convenient to use a colorless and transparent receptor layer 3 lined with a base material 2 such as paper, or a white receptor layer 3 lined with a base material 2 such as paper to obtain a reflective image.

The same thing as above can also be done when using a combination of characters, figures, symbols, colors, etc., or graphic patterns formed on a CRT screen by computer operation as an original image. When the image is a fixed image such as a photograph, a printed matter, or an actual object such as a person, still life, or landscape, the same method as described above can be performed by using an appropriate means such as a video camera as a medium.
Furthermore, when creating signals for each color separation pattern from the original image, an electronic plate making machine (color scanner) used for photolithography for printing may be used.

As explained above, since the receiving layer of the thermal transfer sheet of the present invention is a product made of a crosslinked product of polyurethane polyol and polyisocyanate, it has a continuous gradation like that of a photograph directly by electric signals. A colored image can be obtained.

Further, it is possible to obtain a colored image with high density and high transparency, and also to obtain a clear, high-resolution image that does not fade even after being stored for a long period of time.

Furthermore, during thermal transfer, there is no peeling transfer of the thermal transfer layer to the thermal transfer layer, there is no fusion between the thermal transfer sheet and the thermal transfer sheet, and high quality image quality with excellent dot shape reproducibility of the thermal head is obtained. It has various effects such as being able to.

Hereinafter, the present invention will be explained in more detail with reference to specific examples, but the present invention is not limited to these examples.

Example 1 Thickness with corona treatment on one side as support
Using a 9 μm PET film (S PET manufactured by Toyobo Co., Ltd.), a coating composition for a thermal transfer layer having the following composition was applied onto the corona-treated film surface using wire bar coating so that the dry thickness was 1 μm. and silicone oil (X-
41.4003A, manufactured by Shin-Etsu Silicone) with a dropper, spread it over the entire surface, and applied a back treatment coat to form a thermal transfer sheet.

Paint composition dispersion paint for thermal transfer layer (Kayaset Blue 714 manufactured by Nippon Kayaku Co., Ltd.)
4 parts by weight Ethyl hydroxyethyl cellulose (manufactured by Hercules) 5 parts by weight Toluene 40 parts by weight Methyl ethyl ketone 40 parts by weight Dioxane 10 parts by weight 150 μm synthetic paper as base material (manufactured by Oji Yuka)
YUPO-FPG-150), apply a receptive layer coating composition with the following composition onto this surface by wire bar coating so that the dry thickness is 5 μm, dry with warm air, and then place in a 100℃ oven for 30 minutes. A heat curing process was performed (the solvent was thoroughly blown off).

Coating composition for receptor layer Γ Takerak E-550 (25% toluene, methyl ethyl ketone solution, polyurethane polyol manufactured by Takeda Pharmaceutical Industries): 10 parts Γ Takenate E-40 (25% ethyl acetate solution, polyisocyanate manufactured by Takeda Pharmaceutical Industries): 6 Further, a release layer coating composition having the following composition was coated on the surface of the receptor layer by wire bar coating so that the dry thickness was 0.3 μm to form a thermal transfer sheet. Drying: 100% after temporary drying with a hair dryer
℃ oven for 30 minutes.

Coating composition for release layer ΓKF-393 (manufactured by Shin-Etsu Silicone, amino-modified silicone oil) 2.5 parts ΓX-22-343 (manufactured by Shin-Etsu Silicone, epoxy-modified silicone oil) 2.5 parts Γethanol 95 parts Obtained as above The thermal transfer sheet and the sheet to be thermally transferred are stacked so that the thermal transfer layer and the receiving layer are in contact with each other, and a thermal head is applied from the support side of the thermal transfer sheet to an output of 1 W/dot, a pulse width of 0.3 to 4.5 m ^sec , and a dot density of 3. As a result of recording under the conditions of dots/mm, Macpeth
The optical reflection density of the high color density recording area was measured using an RD918 reflection densitometer, and a value of 1.5 was obtained. The color tones obtained at this time have the same transparency as when colored by monomolecular dispersion of each dye, and furthermore, high-quality images with extremely excellent dot shape reproducibility of the thermal head are obtained. It was done.

When the recorded sheet was left in an oven at 60° C. for 7 days and a thermal diffusion acceleration test was performed, no image disturbance due to dye diffusion was observed, and no decrease in the density of the recorded area occurred.

In addition, when we conducted a light resistance test on the recorded sheet above using a sunshine weather meter, we found that
An excellent value of JIS grade 3 or higher was obtained.

Example 2 Recording was carried out in exactly the same manner as in Example 1, except that the receiving layer coating composition in Example 1 was replaced with the following composition.

Coating composition for receptor layer Γ Takerak E-550 (25% toluene, methyl ethyl ketone solution, polyurethane polyol manufactured by Takeda Pharmaceutical Industries): 10 parts Γ Takenate D110N (25% ethyl acetate solution polyisocyanate manufactured by Takeda Pharmaceutical Industries): 9 parts Obtained Similar to Example 1, the resulting image was of high quality with excellent color development, storage stability, dot reproducibility, and light resistance.

Example 3 Recording was carried out in exactly the same manner as in Example 1, except that the receiving layer coating composition in Example 1 was replaced with the following composition.

Coating composition for receptor layer ΓTakerak XE-916 (25% toluene solution, polyurethane polyol manufactured by Takeda Pharmaceutical Co., Ltd.): 10 parts ΓTakenate E-40 (25% ethyl acetate solution, polyisocyanate manufactured by Takeda Pharmaceutical Co., Ltd.): 9 parts Obtained As in Example 1, the image shows color development,
The image quality was high with excellent storage stability, dot reproducibility, and light resistance.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, and FIG. 1 is a longitudinal sectional view showing one embodiment of the thermal transfer sheet of the present invention, and FIG. 2 is a longitudinal sectional view showing another embodiment of the thermal transfer sheet of the present invention. , FIG. 3 is a longitudinal sectional view showing an example of a thermal transfer sheet, and FIG. 4 is a longitudinal sectional view showing a state in which the thermal transfer sheet and the thermal transfer sheet are overlapped. 1... Heat transfer sheet, 3... Receptive layer, 4...
Heat transfer sheet.

Claims (1)

[Claims] 1. A thermal transfer sheet having a receptor layer that receives dyes transferred from the thermal transfer sheet when heated, characterized in that the receptor layer is mainly composed of a crosslinked product of polyurethane polyol and polyisocyanate. Thermal transfer sheet.