JPS6216189A - Thermal transfer material and multicolor thermal transfer recording method - Google Patents

Abstract

PURPOSE:To provide a thermal transfer recording medium and a recording method by which an excellent precise multicolor image can be formed and high-speed recording can be peformed, by incorporating a plurality of coloring agents having the same hue but differing in transfer starting temperature and a coloring agent having a lower transfer starting temperature and a hue different from the same hue mentioned above. CONSTITUTION:The thermal transfer recording medium 1 comprises a coloring agent containing layer 3 on a heat-resistant base 2. The layer 3 comprises at least two coloring agents (the first coloring agent group) having the same hue but differing in transfer starting temperature and at least one coloring agent (the second coloring agent) having a hue different from the above-mentioned hue and a lower transfer starting temperature. The second coloring agent starts to be transferred at a temperature of not lower than t1, and the transfer quantity thereof is saturated at a transfer finishing temperature t2. On the other hand, the coloring agents 1a, 1b, 1c in the first coloring agent group have respective transfer starting temperatures t3, t5, t7 which are higher than t1, and the transfer quantity thereof is saturated at a transfer finishing temperature t8. In a temperature range t3-t8, the mixing ratio of the coloring agents of the first coloring agent group to the second coloring agent is gradually varied, so that the variations in the hue of the recorded image can be controlled by regulating the applied temperature.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a thermal transfer recording medium used in a thermal transfer recording method, in particular, to easily control the tone of the resulting image by changing the applied temperature. The present invention relates to a thermal transfer recording medium that can be used to transfer images, and a multicolor thermal transfer recording method using the recording medium.

(Prior Art) In recent years, with the rapid development of the information industry, various information processing systems have been developed, and recording methods and devices suitable for each information processing system have been developed. One of them is the thermal recording method, which has been widely used recently because the equipment used is lightweight, compact, noiseless, and easy to operate and maintain.

Among these thermal recording methods, one that has recently received particular attention is the thermal transfer recording method. This recording method generally uses a heat-sensitive transfer recording medium in which a heat-transfer layer formed by dispersing a colorant in a heat-fusible binder or a dye layer containing a sublimation dye is provided on a sheet-like support. The transfer recording medium is weighted on the recording material so that its thermal transfer layer or dye layer is in contact with the recording material, and heat is supplied from the support side of the transfer recording medium by a thermal head or the like to melt the thermal transfer 5.
By transferring a layer or a sublimated dye onto a recording material, a transferred recorded image corresponding to a heat supply pattern is formed on the recording material.

Such a thermal transfer recording method has conventionally been used mainly for forming monochrome recorded images, but recently it is being considered as a method for recording multicolor images or full color images. When forming a multicolor image using this thermal transfer recording method, conventionally, transfer recording media are used that are coated with so-called primary colors of cyan, macenta, yellow, or in addition to these, black. By performing heating many times, a multicolor image is formed on the recording material by subtractive color mixing.

In addition, Japanese Patent Laid-Open No. 53-4353 discloses a method of performing multicolor thermal transfer recording using a heat-sublimable dye ink ribbon in which a transfer layer containing heat-sublimating dyes having different heat sublimation temperatures is provided on a base layer.
This is proposed in Publication No. 8. However, the difference in the heat sublimation temperature of the heat sublimable dyes used in this method is around 100°C (100°C), and the difference in the heat sublimation temperature of the heat sublimable dyes used in this method is around 100°C (100°C). So this big,
It was not possible to create a precise image with sufficient color gradation by creating a large temperature difference.

[The problem that the invention attempts to solve]

That is, in the case of a multicolor thermal transfer recording method using transfer recording media of a plurality of primary colors, the time required for image formation is
Compared to forming a monochromatic image, this method requires time proportional to the number of primary colors used, and the problem of color shift in recorded images cannot be avoided. Furthermore, although various methods can be used to develop color density gradations, this is basically done by changing the area of the pixels that form the image, and sufficient gradation cannot be achieved. It was not yet possible to do so. On the other hand, when trying to form a multicolor image using one transfer recording medium,
For the reasons mentioned above, a precise image with excellent color gradation could not be obtained.

The present invention has been made in view of the above points, and the main object of the present invention is to provide a new thermal transfer recording method that eliminates the drawbacks of the conventional thermal transfer recording method when forming a multicolor image as described above. An object of the present invention is to provide a medium and a multicolor thermal transfer recording method.

Still another object of the present invention is to provide a thermal transfer recording medium capable of high-speed recording, capable of forming a precise multicolor image with excellent halftone hue gradation and appearance by applying heat twice. The purpose is to provide a method.

[Means for solving problems]

That is, the thermal transfer recording medium of the present invention includes a plurality of colorants of similar colors having different transfer start temperatures, and a colorant having a transfer start temperature lower than these transfer start temperatures and different from the above-mentioned similar colors. It is characterized by containing a coloring agent of color.

Further, the multicolor thermal transfer recording method of the present invention includes a plurality of colorants of similar colors having different transfer start temperatures, and a transfer start temperature lower than these transfer start temperatures, and the similar colors are different from each other. The present invention is characterized by the step of applying different temperatures to desired different parts of a thermal transfer recording medium containing colorants of different colors in accordance with the color density of a desired image.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing the most basic aspect of the thermal transfer recording medium of the present invention. The heat-sensitive transfer recording medium of the present invention is composed of at least a colorant-containing layer 3 containing a plurality of colorants on a heat-resistant support 2, and in addition to these layers, various layers may be added as desired. It may be laminated.

The colorant-containing layer 3 contains two or more colorants of similar colors having different transfer start temperatures (hereinafter referred to as the first colorant group);
A coloring agent that has a different hue from these and has a lower transfer initiation temperature than these (hereinafter referred to as the second coloring agent)
The transfer initiation temperature of a colorant according to the present invention refers to a temperature defined as follows:
That is, a certain amount (for example, 100n+q) of colorant is placed on a transparent polyethylene terephthalate film in a 5×5 m area.
A hot plate at a predetermined temperature is pressed onto the dye at a pressure of 209/cm' for 1 second.

The temperature of the hot plate at which the optical density of the film at the maximum absorption wavelength of the colorant captured (transferred) to the film (recording material) in this manner shows 0.10 is defined as the transfer start temperature.

Furthermore, similar coloring agents as used in the present invention refer to those whose hues are very similar to each other, for example, all of these coloring agents or belonging to the same group of any of the three primary colors of cyan, macenta, and yellow. It is necessary. On the other hand, "another different color" for specifying the second colorant refers to a hue that is clearly different from the hue of the first colorant group, for example, the first colorant group or cyan. If it belongs to one of the three primary colors of , macenta, and yellow,
It is necessary to reach different groups.

It is preferable that the first colorant group contains three or more types of colorants. In addition, it is preferable that the difference in transfer start temperature of the dyes belonging to the first colorant group is at least 5°C or more, such as the lowest transfer start temperature and the highest transfer start temperature. It is more preferable that the difference is at least ℃. However, it is not appropriate to have a difference of more than 50°C. Also,
When three or more types of colorants are used, it is preferable that the transfer start temperatures of these colorants are approximately equal in number.

On the other hand, the second colorant is composed of one or more types, and all of them or the colorant having the lowest transfer initiation temperature among the colorants that reach the first colorant group (hereinafter abbreviated as colorant 1a) ) is required to have a transcription initiation temperature lower than When a second colorant or multiple colorants of similar colors are used, the transfer start temperature of the lowest colorant and the highest temperature of these second colorants are the same as in the case of the first colorant group. It is desirable that the transfer start temperature differs by at least 5°C or more, and more preferably by 10°C or more.

Further, it is preferable that the transfer end temperature of the colorant having the highest transfer start temperature among the second colorants has a difference of 5° C. or less from the transfer start temperature of the colorant 1a. Here, the transfer end temperature is the temperature at which the optical density of the film is determined by the same method as the transfer start temperature or 0.9.
It refers to the temperature of the hot plate when it shows 0.

If the above temperature difference becomes too large, the temperature range for producing a change in the color density of the first colorant becomes too narrow, or the temperature range for producing a change in the color density of the first colorant becomes too narrow. This is not preferable because the sum of the temperature range and the temperature range for expressing the hue change of the mixed color of the first colorant and the second colorant becomes too wide.

Further, the thermal transfer recording medium of the present invention may contain, in addition to the first colorant group and the second colorant, a third colorant having a hue different from any of these. In this case, it is appropriate that the third colorant has a transfer start temperature in a region apart from the region where the transfer start temperatures of the first colorant group and the second colorant exist.

As the colorant, any commercially available colorant can be used as appropriate as long as it has a predetermined transfer start temperature. Particularly suitable colorants include known sublimation dyes selected from disperse dyes such as anthraquinone compounds and azo compounds, and basic dyes such as indolenine compounds and leucophenoxazine compounds. Dyes can be used.

However, from a practical point of view, those having a transfer initiation temperature of 200°C or less are preferred, and specifically, for example, Kayaset Yellow AG, Kayaset Red B, Kayaset Blue 906 (all of which are manufactured by Nippon Gunpaku ■, Product name), Resi Regi Yellow TGL, Ceres Blue GN, Resi Regi Red TB, Reso 1 Non Yellow GRN (manufactured by Bayer, product name), Dianics Iniro-60-
3E, Dianex Brilliant Yellow 5G-E
, Dianix Scarlet 3R-FE, Dianix Scarlet PTB-67C or higher, manufactured by Mitsubishi Kasei ■, product name), Miketon Yellow 5G, Miketon Red B
SF, Miketon Blue FTK C or higher, Mitsui Toatsu ■
product name), Sumikaron Yellow E-4GL, Sumikalon Red F-BGL, Sumikalon Blue E-GR
L W can be mentioned.

The colorant-containing layer 3 is formed by dispersing a plurality of colorants in a binder resin. As the binder resin, the coloring agent dispersed therein (having a melting point or softening point at a temperature higher than the temperature at which it completely sublimes) is suitable.

Examples of such binder resins include phenol resin, melamine resin, epoxy resin, silicone resin, urea resin, diallyl phthalate resin, alkyd resin,
Acetal resin, acrylic resin, methacrylic resin, polyester resin, starch and its derivatives, cellulose resin, halogenated vinyl resin, polyolefin, polystyrene, polyvinyl acetal, polyamide, polyvinyl alcohol, polycarbonate, polysulfone, polyether sulfone, polyester, polyether , polyacrylonitrile, polyimide, polyamideimide,
Examples include polymer blends such as AS resin and ABS resin.

As the support 2, conventionally known films and papers can be used as they are, such as films of relatively heat-resistant plastics such as polyester, polycarbonate, triacetyl cellulose, polyamide, and polyimide, cellophane, and parchment paper. etc. can be suitably used. The thickness of the support is preferably about 2 to 15 mm when a thermal head is used as a heat source during thermal transfer, but it is preferable to use a heat source that can selectively heat the colorant-containing layer, such as a laser beam. In this case, there are no particular restrictions on the thickness. In addition, when using a thermal head, the surface of the support that comes into contact with the thermal head may be made of silicone resin, fluororesin, polyimide resin, epoxy resin, phenol resin, melamine resin, etc.
The heat resistance of the support may be improved by providing a heat-resistant protective layer made of nitrocellulose or the like.

Further, the support body 2 may be multi-layered as necessary for reinforcement or in accordance with the adoption of other heating methods such as energization heat generation. - For example, as disclosed in Japanese Unexamined Patent Publication No. 58-12790, conductive fine particles such as carbon black or metal are dispersed in the support 2 to increase its specific resistance to 102 to 10.
It may have a conductivity of about 3Ω·Cm, or a vapor-deposited metal film may be formed between the conductive heat-generating support 2 and the colorant-containing layer 3, as disclosed in JP-A-58-220795. A highly conductive layer consisting of, etc. may be provided.

The colorant-containing layer 3 is formed on the support 2. Specifically, the method for forming the heat-sensitive transfer recording medium of the present invention includes, for example, kneading a colorant and a binder resin with a suitable solvent to form a dispersion. , roll coater, plate coater,
Examples of methods include applying the coating onto the support 2 using any coating means such as a bar coater, and drying it if necessary.

The thickness of the colorant-containing layer 3 is usually in the range of 0.1 to 10 μm, preferably 0.5 to 5 μm.

Next, the principle of the thermal transfer recording method of the present invention using such a thermal transfer recording medium of the present invention will be briefly explained based on the drawings. FIG. 2 is a schematic diagram showing the thermal transfer recording characteristics of the thermal transfer recording medium of the present invention, and FIG. 3 is a schematic diagram showing the thermal transfer recording characteristics of the thermal transfer recording medium containing only one sublimable dye for each color. It is a schematic diagram.

The second colorant having a low transfer start temperature (kl) contained in the thermal transfer recording medium of the present invention starts transferring when a temperature of L or higher is applied, and as the temperature rises, the transfer starts. The transfer amount increases, and the transfer amount becomes almost saturated at the transfer end temperature (h). On the other hand, each colorant (Ia, 1b, and Ic) of the first colorant group of a different color from the second colorant has a transfer start temperature (t3, t5, and t7) higher than t. When a temperature higher than LA is applied, the transfer starts, and as the temperature rises, the transfer amount increases, and at the transfer end temperature (to) of the colorant 1c, the transfer amount is approximately saturate.

Therefore, even if a temperature without the L1 groove is applied to this thermal transfer recording medium, none of the colorants will be transferred and recording cannot be performed.1. In the temperature range of -12, as the applied temperature increases, the density of the recorded image based on the second colorant increases to a whistle, and the gradation of the color density of the second colorant of the recorded image changes. can be expressed by controlling the applied temperature. Further, when a temperature of 13 or more is applied to this thermal transfer recording medium, the colorant of the second colorant group is also transferred simultaneously with the transfer of the first dye. Therefore, 1. In the temperature range of ~111, as the applied temperature increases, the transfer amount of the colorant of the first colorant group gradually increases, so that the colorant of the first colorant group and the second colorant are The mixing ratio gradually changes, and the hue gradually changes from a single color of the second colorant to a mixed color of the second colorant and the colorant of the first colorant group, and the hue of the recorded image changes. The gradation changes can be applied to control the temperature.

Even for thermal transfer recording media containing only one sublimable dye as the dye of the first colorant group, the amount of transfer (amount of sublimation) changes by changing the temperature, as shown in Figure 3, and the hue changes. Does a gradation change occur or does the transfer start temperature (t
3) Since the temperature range at which the transfer amount is almost saturated is relatively narrow, the transfer amount of the first sublimable dye can be controlled with high precision by changing the temperature applied to the thermal transfer recording medium. It is difficult to control the hue. However, since the thermal transfer recording medium of the present invention contains a plurality of colorants of the first colorant group with different transfer start temperatures, when looking at the individual colorants, the gradient of change in transfer amount with respect to temperature is the third. Although it is large as in the case of the figure, as shown in FIG.
Compared to the figure, it is much gentler. Therefore, by changing the temperature applied to the thermal transfer recording medium within a wide range from t3 to t[I, the transfer amount of the first colorant group can be more easily controlled. The gradation expression of the hue of the tone is good.

Furthermore, if multiple types of colorants having different transfer start temperatures are included as the second colorant, similar to the first colorant group, the gradient of change in transfer amount with respect to temperature will similarly be gentle,
As described above, in the thermal transfer recording medium of the present invention, it is possible to more easily control the shading of a single color of the second colorant. It is also possible to contain a coloring agent of No. 3.

In this case, for example, if the first colorant is yellow, the second colorant is magenta, and the third colorant is cyan, as the applied temperature increases, the color tone developed by the thermal transfer recording medium will be:
Since the color changes from light yellow to dark yellow to orange to black, it is possible to perform multicolor thermal transfer recording by controlling the applied temperature.

As described above, the thermal transfer recording method of the present invention uses a thermal transfer recording medium in which the slope of the temperature dependence curve of the transfer amount of one color component is gentle, so that the temperature dependence curve of the transfer amount of one color component can be adjusted according to the tone of the desired recorded image. By applying different temperatures to a thermal transfer recording medium using a temperature applying means such as a recording head, it is possible to form an image that reproduces fine tones.

However, the recording operation is not particularly different from conventional thermal transfer recording methods, except that different temperatures are applied to predetermined portions of the thermal transfer recording medium depending on the desired image tone. That is, the colorant-containing layer of the thermal transfer recording medium and the recording surface of the recording material are stacked so as to face each other,
Recording is performed by installing a thermal head or the like at a position opposite to a supporting member such as a platen that supports the surface of the recording material opposite to the recording surface, and supplying heat corresponding to the desired recording pattern to the head. or will be implemented. In a thermal transfer medium to which heat is applied, the heat spreads across the support to the colorant-containing layer,
Due to this heat, the colorant in the colorant-containing layer is captured by the recording material at a rate corresponding to the applied temperature, thereby forming an image corresponding to the recording pattern on the recording material.

Note that in the case of the current heating method, the thermal transfer medium itself generates heat by applying current from a needle-like or multi-stylus-like recording electrode instead of a thermal head, but of course heat is applied by such a method. It's okay.

〔Effect of the invention〕

According to the heat-sensitive transfer recording medium and heat-sensitive transfer recording method of the present invention, a desired color density can be easily achieved by changing the temperature applied to the heat-sensitive transfer recording medium. It has excellent expression of gradation ``i'', and it has become possible to form high-quality monochrome or multicolor images.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on Examples.

Example 1 Polyester resin Atrac (trade name, manufactured by Kao ■) 100 parts by weight to dye Miketon Polyester Yellow Soshiku trade name,
15 parts by weight dye Miketone Polyesterlet BSF (product name, manufactured by Mitsui Toatsu Chemicals)
5 parts by weight Dye C Miketone Polyester Red T3B (trade name, manufactured by Mitsui Toatsu Chemical ■) 5 parts by weight Dye D Kayaset Red B (trade name, manufactured by Nippon Kayaku ■) 5 parts by weight Methyl ethyl ketone 1000 parts by weight Above composition The mixture was stirred thoroughly and uniformly in an attritor, and then a wire bar was applied to a 3.5μA thick film made of polyethylene terephthalate and rate so that the coating thickness after drying was approximately 10μ. A thermal transfer recording medium was prepared.

Note that the transfer start temperature of dye A is 65°C, and that of dye B
The transfer start temperature of Dye C was 78°C, the transfer start temperature of Dye C was 89°C, and the transfer start temperature of Dye C was 100°C.

This thermal transfer recording medium is attached to a thermal transfer recording device (Kyanoward CW-453, trade name, manufactured by Canon ■), and the thermal energy supplied to the thermal head is 0.3 to 0.5 mJ/.
When forming a color image on a polyester film by changing the dot range in eight steps and changing the temperature applied to the thermal transfer recording medium in eight steps in the range of 65 to 145°C, the color changed from yellow to orange to red. A recorded image with clear color gradation was obtained.

Example 2 Polyester resin (trade name, manufactured by Kao ■) 100 parts by weight dye 5 parts by weight Dye E Miketone Polyester Yellow 5G (trade name, manufactured by Mitsui Toatsu Chemical ■) 5 parts by weight dye F Kayaset Yellow G (product name, manufactured by Nippon Kayaku EL) 5 parts by weight Dye C8
Part by weight Dye D8 Part by weight Methyl ethyl ketone 1000 parts by weight A thermal transfer recording medium was prepared in the same manner as in Example 1 except that the above composition was used. The transfer start temperature of dye E was 72°C, and the transfer start temperature of dye F was 76°C.

Using the same apparatus as in Example 1, this thermal transfer recording medium was
Thermal energy supplied to the thermal head is 0.3 to 0.5 mJ.
/dot in 10 steps, and the temperature applied to the thermal transfer recording medium was changed in 10 steps in the range of 65 to 145°C to form a color image on a polyester film. A recorded image with clear color gradation ranging from bright yellow to orange to red was obtained.

Example 3 Polyester Jugetsu Atra Nku (trade name, manufactured by Kao ■) 100 parts by weight Dye 5 parts by weight Dye E
5 parts by weight Dye F 5 parts by weight Dye G Kayaset Red 126 (Product name, manufactured by Nippon Kayaku ■) 5 parts by weight Dye C 5 parts by weight Dye D 5 parts by weight Dye H Dyanix Pull "-PT-67 (Product name, manufactured by Mitsubishi Kasei Co., Ltd.) 15 parts by weight Methyl ethyl ketone 1000 parts by weight A thermal transfer recording medium was prepared in the same manner as in Example 1 except that the above composition was used.The transfer start temperature of dye G was 110°C. Yes, the transfer start temperature of dye H is 138
It was ℃.

Using the same apparatus as in Example 1, this thermal transfer recording medium was
Thermal energy supplied to the thermal head is 0.3 to 0.7 mJ
/ dot in 15 steps and the temperature applied to the thermal transfer recording medium was changed in 15 steps in the range of 65 to 200°C to form a color image on a polyester film. It has a clear color gradation ranging from yellow to orange, red, bluish-purple, and then to black! I was able to get a picture of Kaya.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the basic structure of the thermal transfer recording medium of the present invention. FIG. 2 is a schematic diagram showing the thermal transfer recording characteristics of the thermal transfer recording medium of the present invention, and FIG. 3 is a schematic diagram showing the thermal transfer recording characteristics of the thermal transfer recording medium containing only one sublimable dye for each color. It is a schematic diagram. 1-m-thermal transfer recording medium 2-m=support 3---colorant-containing layer

Claims (1)

[Scope of Claims] 1) A plurality of colorants having similar colors having different transfer start temperatures, and a colorant having a transfer start temperature lower than these transfer start temperatures and having a different color from the similar color. A thermal transfer recording medium characterized by containing a colorant. 2) Contains multiple types of colorants of similar colors with different transfer start temperatures, and colorants of other colors different from the similar colors and having transfer start temperatures lower than these transfer start temperatures. A multicolor thermal transfer recording method comprising the step of applying different temperatures to desired different parts of a thermal transfer recording medium depending on the color density of a desired image.