JP2772347B2 - Dye transfer type thermal recording method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a dye transfer type thermal recording in which an image is formed by transferring a sublimable dye on a dye transfer member to a dyeing layer on an image receiving member. The present invention relates to a dye transfer type thermal recording method for multiple recordings using the same spot a plurality of times.

2. Description of the Related Art Dye transfer type thermal recording using a sublimable dye is a full-color recording method capable of recording density gradation for each recording dot. Is being done. As a report of multiple recordings, "N-times mode recording characteristics of sublimation transfer type thermal recording medium"
(2nd Non-Impact Printing Technology Symposium, pp. 101-104, 1985) and "Examination of Sublimation Films for Multiple Recordings" (Preprints of the 1986 National Meeting of the Institute of Image Electronics Engineers of Japan). Both relate to the multiple-time recording characteristic by the relative speed method. A simple repetition method in which the same portion is repeated N times for multiple recordings, and an n-times mode relative speed method in which the supply speed of the dye transfer member to the image receiving member is set to 1 / n and recording is substantially performed n times many times There are two. The relative speed method is compatible with relative speed recording and requires some contrivance for smoothness between the dye transfer body and the image receiving body.However, since the unrecorded part of the transfer body is always supplied, the actual number of repetitions is simply repeated. It can be larger than the system.

Then, through the spherical spacer particles between the transfer body and the image receiving body,
A recording density of about 1.8 is realized with the number of repetitions n = 12.
Then, the transfer member and the image receiving member are allowed to run in close contact with each other.
1.0 has been achieved.

Problems to be Solved by the Invention In order to reproduce a full-color image equivalent to normal recording (single recording), a saturation recording density (about 1.5 to 1.8) equivalent to the saturation recording density during normal recording, and particularly, multiple recordings Is a condition that a change in the recording density due to the number of repetitions for the same recording energy is small so that the influence of the recording history does not appear.

In the conventional example, if a sufficient amount of the dye necessary for multiple recordings is ensured, the above-mentioned conditions are satisfied in terms of recording characteristics.However, in order to provide a space between the dye transfer member and the image receiving member, usable dyes are reduced. Limited to dyes with high sublimability. Dyes with high sublimability generally have very poor weather resistance (light fading, dark fading, etc.) and have practical problems. If a dye having high weather resistance and low sublimability is used in the configuration of the conventional example, the recording sensitivity is greatly reduced, and a required recording density cannot be obtained. In the conventional example, it is possible to use a high weather resistance dye having a low sublimation property by adhesion diffusion transfer, but even if a sufficient amount of the dye necessary for recording many times is secured,
The decrease in the recording density due to the increase in the number of repetitions for the same recording energy is large, and as a result, the saturation recording density obtained at the time of recording many times does not reach a practical level.

The present invention solves the above-mentioned problems, enables a highly practical, highly weatherable, low sublimable dye, has a small decrease in recording density with an increase in the number of recordings for the same recording energy, and has a high saturation recording density up to a large number of times. An object of the present invention is to provide a dye transfer type thermal recording method for multiple recordings, which can be maintained and enables full-color recording equivalent to ordinary single recording at a lower running cost, and has greatly improved multiple recording characteristics. And

Means to solve the problem At least each part of the colorant layer contains a sublimable dye and a binder,
Using a dye transfer member having a color material layer formed on the substrate, wherein the weight concentration of the sublimable dye on the layer surface side is lower than that of the layer substrate side, and dye-dyeing the dye material on the color material layer surface and the substrate. The dye in the color material layer is brought into close contact with the dye layer surface of the image receiving body having the dyeing layer, and selectively heated by the thermal recording head from the back side of the dye transfer body or the back side of the image receiving body to the dye layer. The step of transferring and forming an image on the image receiving member is performed using the same portion of the dye transfer member a plurality of times.

When no space is provided between the dye transfer member and the image receiving member, the transfer of the dye is governed by the diffusion phenomenon of the dye between the color material layer and the dyeing layer. Therefore, paying attention to the change in the dye concentration on the surface of the color material layer during the dye consumption process of multiple recordings, there is no concentration gradient of the dye inside the color material layer in the initial state in the color material layer formed by the ordinary forming method. Sometimes the dye near the surface is consumed, and the dye concentration on the surface of the color material layer is reduced to nearly half of the concentration inside the color material layer. From the second time onward, the dye is also supplied from the inside due to the concentration gradient inside the color material layer, so that the rate of decrease in the dye concentration on the surface of the color material layer becomes very small. Therefore, the change in the recording density during multiple recordings when the same recording energy is applied decreases greatly from the first to the second recording, and the decrease in the recording density thereafter is small. Therefore, in the initial state, by lowering the dye weight concentration on the layer surface side than on the color material layer substrate side to give a concentration gradient inside the color material layer, the dye is supplied from the inside of the color material layer from the first time. As a result, a sharp decrease in the initial recording density caused by a sharp decrease in the dye concentration on the surface of the color material layer is greatly improved.

Example In an image receiving body configured such that the diffusion rate of the dye in the dyeing layer is smaller than the diffusion rate in the coloring material layer of the dye transfer body, the diffusion rate can be qualitatively compared by the following method. It is. When comparing the diffusion rate of a certain dye in the resin A and the resin B, a dye transfer member having a color material layer containing a target dye is formed by forming an image receiving body having the resin A and the resin B as a dyeing layer. It is commonly used to perform transfer recording, and the recording density is simply measured, and more precisely, the amount of the transferred dye is measured by spectrophotometric determination by dye extraction. The higher the diffusion rate of the resin, the higher the recording density or the amount of transfer dye can be obtained. In general, a resin having a lower heat resistance or a lower intermolecular force has a higher diffusion rate, and a resin having a higher heat resistance or a higher intermolecular force has a lower diffusion rate. The larger the ratio between the diffusion speed of the color material layer and the diffusion speed of the dyeing layer, as long as there is no problem with respect to the storability of the color material layer or the recording sensitivity, the higher the transfer speed from the surface of the color material layer to the dyeing layer. On the other hand, the supply speed of the dye from the deep portion of the color material layer to the surface is increased, and the decrease in the recording density at the time of recording many times is greatly improved.

As the dyeing layer, a curable resin having a cross-linking structure and capable of suppressing the diffusion rate of the dye is particularly effective. Even when mixed with a thermoplastic resin, the effect can be obtained by mixing at least 25% by weight. Similarly, a water-soluble resin is also effective as a dyeing layer resin in the sense of suppressing the dye diffusion rate. A water-soluble resin generally contains many polar groups, has a large intermolecular force, and has a low dye diffusion rate. When mixed with other water-dispersible resins, the effect can be obtained by mixing at least 25% by weight.

FIG. 2 shows a configuration example. The transfer body 1 has a color material layer 3 provided on a transfer base 2, and the image receiving body 4 has a dyeing layer 6 provided on an image receiving base 5.

Using the present dye transfer type thermal recording medium, the color material layer of the dye transfer body and the dyeing layer of the image receiving body are in close contact with each other, and recording is performed many times. Is possible. Further, by including a lubricating substance in at least one of the coloring material layer of the dye transfer body or the dyeing layer of the image receiving body of the present thermal recording medium, the running speed of the dye transfer body with respect to the thermal recording head is reduced by the thermal recording of the image receiving body. A number of relative speed methods in which the dye in the color material layer is selectively heated from the back surface of the dye transfer member or the back surface of the image receptor to transfer the dye in the color material layer to the dye layer and form an image on the image receptor at a speed lower than the traveling speed with respect to the head. Also in the multiple recording, it is possible to suppress a decrease in the recording density due to an increase in the relative speed ratio n.

FIG. 5 shows the principle of the n-times mode relative speed method. The transfer member 1 and the image receiving member 4 are pressed against the thermal head 8 by the platen 7 so that the coloring material layer dyeing layer adheres closely. For the speed v of the image receiving member 4 with respect to the thermal head 8, the transfer member 1
The vehicle runs at n (n = 1, 2,...). The traveling direction of the transfer body may be the same direction or the opposite direction to the traveling direction of the image receiving body.

In order to specifically realize the dye concentration distribution in the “dye transfer body including at least a sublimable dye and a binder, and having a color material layer having a lower dye weight concentration on the layer surface side than the layer substrate side on the substrate”. As a method of forming a color material layer, a color material layer is formed by sequentially laminating a plurality of layers having different dye weight concentrations on a substrate in descending order of the concentration, and forming at least a sublimable dye on the substrate. There is a method of forming a color material layer by providing a color material layer composed of an adhesive and then removing a dye near the surface of the color material layer.

Specifically, a) a method of adhering a resin layer to the surface of a color material layer and removing the resin layer after transfer by heating;
b) A method of dissolving and removing the dye on the surface of the colorant layer with a solvent in which the dye is soluble and the binder is hardly soluble.

In the above, it is preferable to form a concentration gradient over the entire inside of the color material layer by stacking several layers, but the two-layer structure that is the easiest to manufacture, that is, a dye high concentration layer containing at least a sublimable dye and a binder, In a dye transfer body in which a dye weight concentration is lower than the high concentration layer and a dye permeable low concentration layer is sequentially laminated on a substrate to form a color material layer, the initial recording density change during multiple recordings is greatly improved. It is possible to do enough. In the two-layer configuration, in order to suppress the initial change in the recording density, it is more preferable to set the dye weight concentration of the dye-permeable low-density layer to 1/2 or less of the dye weight concentration of the dye-high-density layer.
The thickness of the dye-permeable low-concentration layer can be adjusted to the most effective thickness by the ratio of the dye concentration of the dye-permeable low-concentration layer to the dye concentration of the dye-high-concentration layer. The ratio can be adjusted by increasing the ratio when the ratio is high and by decreasing the ratio when the ratio is low.
It is preferable that the thickness be not more than μm. Further, in the two-layer structure, the dye-permeable low-concentration layer can have a function of protecting the dye-high-concentration layer during long-term storage. Sex dye content
50% by weight or more, whereby a large amount of dye can be efficiently held on the dye transfer member,
In addition, since the dye is maintained at a high density, the dye density inside the color material layer can be maintained high until the recording is performed a large number of times.
In order to form the low-density dye-permeable layer with less interference with the high-density dye layer in a two-layer structure, a water-soluble or water-dispersible resin can be used.

FIG. 3 shows a configuration example. The transfer body 1 is a color material layer 3 in which a high-concentration dye layer 9 and a low-concentration dye-permeable layer 10 are sequentially laminated on a transfer substrate 2.

By using the present dye transfer body, the color material layer of the dye transfer body and the dyeing layer of the image receiving body having dye-dyeing properties are closely adhered to each other, and the recording is performed many times. It is possible. Further, by adding a lubricating substance to at least one of the coloring material layer of the present dye transfer body and the dyeing layer of the image receiving body having dye-dyeing properties, the running speed of the dye transfer body with respect to the thermal recording head is reduced by the image receiving speed. In a state where the speed is lower than the running speed of the body with respect to the thermal recording head, the dye in the color material layer is selectively heated from the back of the dye transfer body or the back of the image receiver to transfer the dye in the color material layer to the dyeing layer and form an image on the image receiver. Even in the multiple-speed printing using the speed method, it is possible to perform the multiple-time printing with a small decrease in the initial printing density.

FIG. 1 shows a structural example. A transfer body 1 is a color material layer 3 in which a dye high-concentration layer 9 and a dye-permeable low-density layer 10 are sequentially laminated on a transfer base 2, and an image receiving body 4 is an image receiving base. Dyeing layer 6 on 5
Is formed.

Using this dye transfer type thermosensitive recording medium, the color material layer of the dye transfer body and the dyeing layer of the image receiving body are in close contact with each other, and recording is performed many times, thereby lowering the initial recording density and increasing the recording density by increasing the number of repetitions. It is possible to record many times with little decrease. Also,
By including a lubricating substance in at least one of the coloring material layer of the dye transfer body or the dyeing layer of the image receiving body of the present thermosensitive recording medium, the running speed of the dye transfer body with respect to the thermal recording head is reduced with respect to the thermal recording head of the image receiving body. Relative speed recording multiple times by selectively heating from the back of the dye transfer body or the back of the image receptor to transfer the dye in the colorant layer to the dyeing layer and form an image on the image receptor at a speed lower than the running speed In this case, it is also possible to suppress the decrease in the recording density due to the decrease in the initial recording density and the increase in the relative speed ratio n.

Hereinafter, specific materials used in the present invention will be described.

Examples of the sublimable dye include disperse dyes, basic dyes, and basic dye diformers.

The heating source required for transfer is a thermal head,
There is no particular limitation on heat mode heating by laser or the like. Therefore, various substrates can be used for the dye transfer member and the image receiving member depending on the application. For example, as a substrate of the dye transfer member for the thermal head, polyethylene terephthalate, polyethylene naphthalate, ester polymers such as polycarbonate, amide polymers such as nylon,
Acetylcellulose, cellulose derivatives such as cellophane,
There are imide polymers such as polyimide, polyamide imide, and polyether imide, and a heat-resistant layer or a slip layer is provided on the surface of the substrate that directly contacts the thermal recording head, if necessary.
In addition, in order to perform current recording and induction heating recording, a film obtained by imparting conductivity to the above materials or the like is used.

As the substrate of the image receiving body, various kinds of films such as polyester are usually used as transparent ones, and synthetic papers or coated papers or plain papers mainly made of polyester, polypropylene or the like are used as white ones according to the purpose.

The resin used for the binder forming the color material layer is not particularly limited, but a polyester resin, a butyral resin,
Nylon resin, polycarbonate resin, urethane resin,
Chlorinated polyethylene, chlorinated polypropylene, (meta)
Acrylic resin, polystyrene resin, AS resin, polysulfone resin, polyphenylene oxide, cellulose derivative,
These can be selected and combined according to the required characteristics.

Dye-dyeable substances used for the dyeing layer include polyester, polyamide, acrylic resin, acetate resin, various cellulose derivatives, starch, polyvinyl alcohol resin, and the like, and further, as the curing resin, acrylic resin, acrylic acid, acrylic acid ester , Polyester, polyurethane, polyarylate, polyamide, acetate, and the like, and cured products of heat, light, ultraviolet rays, electron beams, and the like. These may be selected and combined as needed.

As a lubricating substance to be added to the color material layer or the dyeing layer,
For example, petroleum lubricating oils such as liquid paraffin, halogenated hydrocarbons, diester oils, synthetic lubricating oils such as silicone oils, fluorosilicone oils, various modified silicone oils (epoxy-modified, amino-modified, alkyl-modified, polyether-modified, etc.), polyoxy Silicone-based lubricating substances such as copolymers of organic compounds such as alkylene glycols and silicone,
Various fluorine-based surfactants such as fluoroalkyl compounds, fluorine-based lubricating substances such as low-polymerized ethylene trifluoride, waxes such as paraffin wax and polyethylene wax, higher aliphatic alcohols, higher alcohols, higher fatty acid amides, higher There are fatty acid esters and higher fatty acid salts. Among them, liquid lubricating substances include, for example, dimethylpolysiloxane, methylphenylpolysiloxane, methylhydrogenpolysiloxane, fluorosilicone oil, and various other modified silicone oils (epoxy-modified, alkyl-modified, amino-modified, carboxyl-modified, Silicone-based lubricating substances such as alcohol-modified, polyether-modified, alkyl-aralkyl-polyether-modified, epoxy-polyether-modified), copolymers of organic compounds such as polyoxyalkylene glycol and silicone, and the like;
Various fluorine-based surfactants such as organic metal salts and fluoroalkyl compounds, fluorine-based lubricating substances such as low-polymerized ethylene trifluoride chloride, alkylbenzene, polybutene, alkylnaphthalene, alkyldiphenylethane, phosphate, polyalkylene glycol There are synthetic oils such as oils, saturated hydrocarbons, animal and vegetable oils, and mineral oils. These can be selected and used in combination as needed.

Examples of the aqueous solvent used for forming the dye-permeable low-concentration layer include water and alcohol-based solvents, cellosolve-based solvents, and acetone that are compatible with water.

 Hereinafter, the effects of the present invention will be described with reference to specific examples.

As the substrate of the dye transfer member, an aromatic polyamide film (6 μm thick) provided with a heat-resistant lubricating layer was commonly used. PET synthetic white paper was used as the base of the image receiving body. The dyes used have the following structural formula:

A thermal head was used as the recording means, and the recording condition was a recording cycle of 16.7 ms / l, a recording pulse width of MAX 4.0 ms, a resolution of 6 l / mm, and a recording energy of about 6 J / cm ² (variable).

First, in order to see the effect of the diffusion rate of the dye in the colorant layer and the dyeing layer, the recording characteristics of the following combination of the dye transfer member and the image receiving member were compared by a simple repetition method.

<Example 1> An ink prepared by dissolving 4 g of a dye having the following structural formula and 4 g of a butyral resin (ESLEK BX-1) as a binder in a mixed solvent of 42 g of toluene and 18 g of MEK on a substrate was coated with a wire bar. Coating and drying were performed so that the dye coating weight was 1.0 g / m ² to obtain a dye transfer body.

On a substrate, 66.6 g of a saturated linear polyester resin dispersion (Toyobo Co., Ltd. Vironal MD-1200), 31.6 g of a silane-based polymer / colloidal silica composite emulsion (Hoechst Gosei Co., Ltd. Movinyl 8020), a surfactant (trade name) : PE
(G-6000S, Sanyo Chemical Industries, Ltd., PEG-6000S) 1.8 g of a mixed aqueous dispersion was applied using a wire bar so that the applied film thickness was about 5 μm, and was sufficiently dried to obtain an image receiving body.

<Example 2> An ink obtained by dissolving 4 g of the same dye as in Example 1 and 4 g of an AS resin (Denka Styrol AS-SU) as a binder in 60 g of monochlorobenzene was dye-coated on a substrate with a wire bar. Coating and drying were performed so that the working weight was 1.0 g / m ² to obtain a dye transfer member.

 The same image receiver as that of Example 1 was used.

<Comparative Example 1> On a substrate, 4 g of the same dye dye as in Example 1 and a linear saturated polyester resin as a binder (Toyobo Co., Ltd. Byron RV29)
0) An ink in which 4 g was dissolved in 60 g of monochlorobenzene was applied with a wire bar so as to have a dye coating weight of 1.0 g / m ^2, and dried to obtain a dye transfer body.

 The same image receiver as that of Example 1 was used.

<Comparative Example 2> An ink prepared by dissolving 4 g of the same dye dye as in Example 1 and 4 g of polysulfone resin (Nissan Chemical Co., Ltd. P-1700) as a binder in 60 g of monochlorobenzene on a base was dye-coated with a wire bar. Was adjusted to 1.0 g / m ² to obtain a dye transfer member.

 The same image receiver as that of Example 1 was used.

<Comparative Example 3> The same dye transfer body as the dye transfer body of Comparative Example 1 was used.

The image receptor is a polyester urethane acrylate resin (Dainippon Ink Chemical Co., Ltd. DEFENSA MCF-3M-
2), methyl ethyl ketone / ethyl acetate (mixing ratio 1/1) comprising an ultraviolet curing initiator (Nippon Ciba Geigy Co., Ltd. Irgacure 184, 5% by weight based on polyester urethane acrylate resin) and a saturated polyester resin (Toyobo Co., Ltd. Byron 200) 3) Apply the solution (prepared so that the weight ratio of the UV curable resin to the total resin solid content = 15%) with a wire bar so that the dry film thickness is about 5 μm, and apply the solution at 60 ° C.
After drying for 2 minutes, the product was irradiated with a 1 kW mercury lamp for 2 minutes and cured to form a dyed layer.

<Example 3> The same dye transfer member as the dye transfer member of Comparative Example 1 was used.

The receiver used in Comparative Example 3 was such that the ratio of the dyed layer of the UV-curable resin to the total resin solid content was 25% by weight.

<Example 4> The same dye transfer member as the dye transfer member of Comparative Example 1 was used.

The receiver used in Comparative Example 3 was such that the ratio of the dyed layer of the UV-curable resin to the total resin solid content was 100% by weight.

<Comparative Example 4> The same dye transfer member as the dye transfer member of Comparative Example 1 was used.

The image receiving body was prepared by mixing an aqueous solution of a polyvinyl alcohol resin (Poval 420) and an aqueous dispersion of a saturated polyester (Toyobo Co., Ltd. MD-1200) on a substrate, and then mixing the polyvinyl alcohol resin solid content with respect to the total resin solid content. 15 ratio
A coating solution having a weight% was used, and the coating solution was sufficiently dried after coating so that a dry film thickness was about μm, and a dyed layer was used.

<Example 5> The same dye transfer member as the dye transfer member of Comparative Example 1 was used.

In the image receiving body, the ratio of the polyvinyl alcohol resin solids to the total resin solids in the dyeing layer was 25% by weight in Comparative Example 4.
Was used.

<Example 6> The same dye transfer member as the dye transfer member of Comparative Example 1 was used.

The image receiver used in Comparative Example 4 was such that the ratio of the polyvinyl alcohol resin solids to the total resin solids in the dyeing layer was 100% by weight.

Using the combination of the dye transfer member and the image receiving member of Examples 1 to 6 and Comparative Examples 1 to 4, the recording density change at the same recording energy in the simple repetition multiple printing = the third recording density
The first recording density (%) was measured. The recording energy was adjusted so that the first recording density was about 2.0. The results are shown in Table 1.

Further, in order to examine the diffusion speed of the used binder resin, using the dye transfer member used in Example 1, the recording density in the case where the used binding resin was used as the dyeing layer was examined. That is, when arranged in ascending order of diffusion speed, the results are as follows.

Butyral resin> AS resin> Example 1 dyeing layer (mainly polyester)> Polyester resin (used in dyeing layer in Example 1, etc., Comparative Example 3 etc.)> Polyester resin (used in color material layer in Comparative Example 1, etc.) )> Polysulfone resin> UV curable resin (used in the color material layer of Comparative Example 3 etc.)> Polyvinyl alcohol resin (used in the dyeing layer of Comparative Example 4 etc.) Next, the effect of the diffusion speed of the color material layer / dyeing layer in the relative speed method multiple recording method was examined.

<Example 7> The same dye transfer member as the dye transfer member of Example 1 was used.

As the image receptor, a silicone surfactant (KF393, Shin-Etsu Chemical Co., Ltd.) was used based on the total solid content of the dyeing layer resin of the image receptor of Example 4.
5) was added in an amount of 0.5 part by weight.

Using the dye transfer body and the image receiving body, the color material layer surface of the dye transfer body and the dyeing layer surface of the image receiving body are brought into close contact with each other, and the running speed of the dye transfer body with respect to the thermal recording head is adjusted with respect to the running speed of the image receiving body with respect to the thermal recording head. When transfer recording was performed a number of times at 1/5 of the speed (n = 5) with the relative speed method, the vehicle ran stably and a recording density of 70% of the recording density of normal recording (n = 1) was obtained. .

Next, in order to see the effect of the dye concentration distribution in the color material layer, the following characteristics of the dye transfer body were examined.

<Comparative Example 5> The same dye transfer member as the dye transfer member of Example 1 was used.

<Example 8> The dye transfer body was obtained by further drying only the polyester resin which is the same resin as the color material layer as a dye-permeable low-concentration layer on the color material layer of the dye transfer body of Comparative Example 1, and having a dry film thickness of 0.2. It was quickly coated and dried to a thickness of μm.

<Example 9> The same dye transfer member as that of Comparative Example 1 was used, and the dye on the surface of the colorant layer was transferred to the dye receiving layer of Example 1 at a recording energy of 6 J / cm ^2. The removed one was used.

<Example 10> The dye transfer member used was the same as the dye transfer member of Comparative Example 1, and the surface of the color material layer was washed with methanol to remove the dye from the surface of the color material layer.

<Example 11> A dye transfer material was prepared by using the same resin as that of Example 8 except that the dye-permeable low concentration layer of Example 8 was used and the dye / resin weight ratio was 1 /.
Using an ink of 3 (half the dye concentration of the lower layer high-concentration layer) ink was quickly applied and dried so as to have a dry film thickness of 0.2 μm.

<Comparative Example 6> In the dye transfer body, the same resin as in Example 8 was used for the dye-permeable low-concentration layer of Example 8, and the dye / resin weight ratio was 1 /.
Using an ink of 2 (dye concentration of 2/3 of the lower-dye high-concentration layer), the ink was quickly applied and dried so as to have a dry film thickness of 0.2 μm.

Dye transfer bodies of Examples 8 to 11 and Comparative Examples 5 to 6 and Example 1
Initial density change at the same recording energy in the simple repetition method in combination with the image receiving body used in Step 2 = Second recording density
The first recording density (%) was measured. The recording energy was adjusted so that the first recording density was about 2.0. The results are shown in Table 2.

Next, the effect of the dye concentration in the lower layer of the two-layered color material layer was examined.

<Example 12> On the dye transfer material of the dye transfer material of Comparative Example 1, only a polyester resin which is the same resin as the color material layer was further formed as a dye-permeable low-concentration layer with a dry film thickness of 0.5. The coating was quickly applied to a thickness of μm and dried.

<Example 13> The dye transfer member was the same as the dye transfer member of Example 1, except that the dye in the ink was 5 g, the polyester resin was 3 g, and the color material layer was formed such that the dye coating weight was 1.0 g / m ^2. And further Example 10.
The same dye-permeable low-concentration layer was used.

<Example 14> The dye transfer member was the same as the dye transfer member of Example 1, except that the dye in the ink was 6 g, the polyester resin was 2 g, and the color material layer was formed so that the dye coating weight was 1.0 g / m ^2. And further Example 10.
The same dye-permeable low-concentration layer was used.

Combining the dye transfer members of Examples 12 to 14 and the image receiving member used in Example 1, the change in recording density at the same energy in the simple repetition multiple recording = the fifth recording density / the first recording density (% ). The recording energy was adjusted so that the first recording density was about 2.0. The results are shown in Table 3.

Next, a method for forming a dye-permeable low concentration layer was examined.

<Example 15> A dye transfer body was formed on the color material layer of the dye transfer body of Comparative Example 1.
Further, as a dye-permeable low-concentration layer, a 10% aqueous dispersion of a water-soluble polyester resin (WR-900, Nippon Synthetic Chemical Industry Co., Ltd.) was coated with a fluorine-based surfactant (Dai Nippon Ink Co., Ltd. Megafac F-812). Use a coating solution with 1% added and a film thickness of 0.2μm
What was applied and dried so as to be used was used.

In Example 15, the upper layer could be formed without any dissolution of the lower layer dye at the time of coating the dye-permeable low concentration layer. The dye transfer member of Example 15 and the image receiving member used in Example 1 were combined, and the initial recording density change at the same energy in the simple repetition multiple-time recording = second recording density / first recording density (%) Investigation yielded a value of 75%.

Next, the effect of the dye density distribution in the colorant layer in the relative speed method multiple recording method was examined.

<Example 16> As the dye transfer member, in the dye transfer member of Example 12, both the lower layer (highly dye-concentrated layer) and the upper layer (dye-permeable low-concentration layer) contained 10% by weight of a lubricant (melting point). What added paraffin wax / oleic acid amide mixture weight ratio 1/1) of 50 degreeC was used. The same receiver as in Example 4 was used.

Using the dye transfer body and the image receiving body, the color material layer surface of the dye transfer body and the dyeing layer surface of the image receiving body are brought into close contact with each other, and the running speed of the dye transfer body with respect to the thermal recording head is adjusted with respect to the running speed of the image receiving body with respect to the thermal recording head. When the transfer recording was performed a large number of times at 1/5 of the speed (n = 5) with the relative speed method, the vehicle ran stably and a recording density of 75% of the recording density of the normal recording (n = 1) was obtained. .

Finally, the synergistic effects of the diffusion rate of the dye in the color material layer and the dyeing layer and the distribution of the dye concentration in the color material layer were examined.

<Example 17> The same dye transfer member as the dye transfer member of Example 1 was used.

The same image receiver as that of Example 4 was used.

<Example 18> On the color material layer of the dye transfer material of Comparative Example 2, only the polysulfone resin, which is the same resin as the color material layer, was used as a dye-permeable low concentration layer. The coating was quickly applied to a thickness of μm and dried.

The same image receiver as that of Example 1 was used. <Example 19> The dye transfer material was formed on the color material layer of the dye transfer material of Example 1 and further as a dye-permeable low-density layer. Only a butyral resin, which is the same resin as the material layer, was quickly applied and dried so as to have a dry film thickness of 0.2 μm.

 The same image receiver as that of Example 4 was used.

<Example 20> As the dye transfer member, a color material layer was formed so that the dye in the ink was 5 g, the butyral resin was 3 g, and the dye coating weight was 2.0 g / m ^{2 in} the dye transfer member of Example 1. Further, the same dye-permeable low-concentration layer as in Example 19 was formed. In both the lower layer (high-dye-concentration layer) and the upper layer (dye-permeable low-concentration layer), 5% by weight of a lubricant was used for each layer. (Mixing ratio of paraffin wax / oleic amide with a melting point of 50 ° C 1 /
1) was used.

 The same image receiver as that of Example 7 was used.

Using the combination of the dye transfer member and the image receiving member of Examples 17 to 20 and Comparative Example 2, the change in the recording density at the same recording energy in the simple repetition type multiple recording = Nth recording density / 1st recording density (% ), And the recording density by the relative speed method = n-times mode recording density / normal mode recording density (first recording density) (%) (Example 20 only). The recording energy was adjusted so that the first recording density was about 2.0. The results are shown in FIG.

Effects of the Invention According to the present invention, a rapid decrease in the dye concentration on the surface of the color material layer due to an increase in the number of repetitions in multiple recordings is suppressed, and the decrease in the recording density is greatly improved.

As a result, a highly practical high weather resistance and low sublimation dye can be obtained, the decrease in recording density with an increase in the number of recordings for the same recording energy is small, and a high saturation recording density can be maintained up to a larger number of times. At the running cost, full-color printing equivalent to ordinary one-time printing can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 are cross-sectional views of essential parts showing a dye transfer type thermal recording method according to an embodiment of the present invention, and FIG. 3 is a cross-sectional view of a dye transfer body according to an embodiment of the present invention. FIG. 4 is a diagram showing the principle of recording at a relative speed multiple times, and FIG. 5 is a diagram showing recording density characteristics in a specific embodiment of the present invention. Transfer member: 1, Color material layer: 3, Image receiver: 4, Dyeing layer:
6, Dye high concentration layer 9, Dye permeable low concentration layer 10

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akihiro Imai 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-1-110194 (JP, A) JP-A-62-282973 (JP, A)

Claims (6)

(57) [Claims] A dye having a color material layer on a substrate, wherein at least each part of the color material layer contains a sublimable dye and a binder and the weight concentration of the sublimable dye on the layer surface side is lower than that of the layer substrate side. Using the transfer member, the color material layer surface of the dye transfer member and the dyeing layer surface of the image receiver having a dye-dyeable dyeing layer on the substrate are adhered to each other, and heat recording is performed from the back surface of the dye transfer member or the back surface of the image receiver. The step of selectively heating with a head to transfer the dye in the color material layer to the dyeing layer and form an image on the image receiving body is performed by using the same place of the dye transfer body a plurality of times. Characteristic dye transfer type thermal recording method. 2. The dye transfer according to claim 1, wherein an image receiving member is used in which the diffusion speed of the dye in the dyeing layer is lower than the diffusion speed of the dye transfer material in the colorant layer. Type thermal recording method. 3. A color material layer according to claim 1, wherein a plurality of layers having different dye weight concentrations, each containing at least a sublimable dye and a binder, are sequentially laminated on a substrate from a higher concentration. Dye transfer type thermal recording method. 4. A high-concentration dye layer containing at least a sublimable dye and a binder, and a low-density dye-permeable layer containing at least a sublimable dye and a binder in which the weight concentration of the dye in the layer is lower than that of the high-concentration layer. Are sequentially laminated on a substrate to form a color material layer.
The dye transfer type thermal recording method described in the above. 5. The dye transfer type thermal recording method according to claim 4, wherein the weight concentration of the dye in the dye-permeable low density layer is not more than 1/2 of the dye weight concentration in the high dye density layer. 6. A color material layer which is selectively heated from the back surface of the dye transfer body or the back surface of the image receptor while the traveling speed of the dye transfer body relative to the thermal recording head is lower than the traveling speed of the image receiver relative to the thermal recording head. 2. A dye transfer type thermal recording method according to claim 1, wherein the dye contained therein is transferred to a dyeing layer.