JPH02137976A - Thermal transfer sheet and thermal transfer method - Google Patents

Abstract

PURPOSE:To impart a sharp image with a sufficient density and to form an image superior in various fastnesses, particulary in light resistance and resistance to darkening, discoloring, and fading, by incorporating a dye stabilizer in a dye layer or in the surface thereof. CONSTITUTION:A dye stabilizer is contained in a dye layer of a thermal transfer sheet, or a layer containing the stabilizer is formed on the surface of the dye layer. By transferring the stabilizer to an image forming area simultaneously with the transfer of a dye, an image superior in light resistance and resistance to darkening, discoloring, and fading can be obtained. Alternatively, by transferring the stabilizer to the image forming area before/after the transfer of the dye, an image superior in light resistance and resistance to darkening, discoloring, and fading can be obtained. The stabilizer is an agent which can prevent the deterioration or decomposion of the dye by absorbing or cutting off optical energy, thermal energy, oxidation, and other actions of deteriorating or decomposing the dye. An antioxidant, an ultraviolet light absorber, and a light stabilizer, which are known as additives for a synthetic resin, are practically exemplified.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a thermal transfer sheet and a thermal transfer method using sublimable dyes (thermally transferable dyes), and more specifically to a transfer sheet with excellent light resistance and resistance to darkening and fading. The purpose of the present invention is to provide a thermal transfer sheet and a thermal transfer method capable of forming images.

(Prior Art) Various thermal transfer methods have been known in the past, among which a sublimable dye is used as a recording agent, this is supported on a base sheet such as a polyester film to form a thermal transfer sheet, and a sublimable dye is used as a recording agent to form a thermal transfer sheet. 2. Description of the Related Art Various methods have been proposed for forming a full-color image on an image-receiving sheet in which a dye-receiving layer is formed on a dyeable transfer material, such as paper or a plastic film. In this case, the printer's thermal head is used as a heating means, and a large number of three or four color dots are transferred to the transfer material by extremely short heating, and the multicolor dots create a full-color image of the original. It is intended to reproduce.

The images formed in this way are very clear because the coloring material used is dye, and they have excellent transparency, so the images obtained have excellent intermediate color reproducibility and gradation, and are It is possible to form high-quality images that are similar to images produced by offset printing or gravure printing, and comparable to full-color photographic images.

(The problem that the invention is trying to solve) However,
Since the resulting images are formed from dyes, they generally have poor light fastness compared to images using pigments, and there is a problem in that the images fade or change color quickly when exposed to direct sunlight. In addition, if there is no direct light, for example, there is a problem that the color changes and fades (darkness fades) even indoors, in a file, or when bound in a book. These problems of light resistance and fading can be improved to a certain degree by adding an ultraviolet absorber or an antioxidant to the dye-receiving layer of the transfer material.

However, in the above-mentioned conventional technology, the antioxidant, etc. is uniformly distributed throughout the dye-receiving layer, and most of the transferred dye is present near the surface of the receptor layer, so the antioxidant, etc. There is a problem in that the protective action of dyes is not performed efficiently and the prevention of discoloration and fading is insufficient, and there is a need for a technology that can effectively protect transferred dyes with antioxidants and the like.

Therefore, an object of the present invention is to provide a clear image with sufficient density in a thermal transfer method using a sublimable dye, and to provide the formed image with excellent fastness properties, particularly excellent light fastness and darkening and fading resistance. It is an object of the present invention to provide a thermal transfer sheet and a thermal transfer method that exhibit properties.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention consists of two inventions, and the first invention is a thermal transfer sheet in which a dye layer is formed on the surface of a base film, in which a dye stabilizer is contained in the dye layer or on the surface thereof. A second invention is a thermal transfer sheet characterized by comprising: a dye layer of a thermal transfer sheet in which a dye layer is formed on the surface of a base film; and a receiving layer of an image receiving sheet in which a dye receiving layer is provided on the surface of the base film; This is a thermal transfer method in which the dye stabilizer is transferred to the image forming area before, during, or after the transfer of the dye. .

(Function) A dye stabilizer is included in the dye layer of the thermal transfer sheet, or a layer containing the stabilizer is formed on the surface of the dye layer,
By transferring these stabilizers to the image forming area at the same time as dye transfer, an image with excellent light fastness and dark and fading resistance can be obtained.

Furthermore, according to the method of the present invention, by transferring a stabilizer to the image forming area before and after transferring the dye, it is possible to provide an image with excellent light resistance and resistance to darkening and fading.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The base film of the thermal transfer sheet of the present invention may be any conventionally known film as long as it has a certain degree of heat resistance and strength. Paper, various processed papers, polyester film, polystyrene film, polypropylene film, polysulfone film, aramid film, polycarbonate film, polyvinyl alcohol film, cellophane, etc., and particularly preferred is polyester film.

When the base film as described above has poor adhesion to the dye layer formed on the surface, it is preferable to subject the surface to a brimer treatment or a corona discharge treatment.

The sublimable (thermally transferable) dye layer formed on the base film as described above is a layer in which a dye is supported by an arbitrary binder resin.

As the dye to be used, any dye used in conventionally known thermal transfer sheets can be effectively used in the present invention.
Not particularly limited. For example, some preferred dyes include MS Red G, Macro
lex Red Violet R, Ceres Re
d7B, Samaron Red IIBsL, Re
Examples of yellow dye include Holon Brilliant Yellow fiGL.
, PTY-52, Macrolex Yellow 6G, etc., and as the blue dye, Kayaset Blue 1
4. Vaxolin Blue AP-Fil, Holon Brilliant Blue SR, MS Blue 100, etc. can be mentioned.

As the binder resin for supporting the heat-transferable dye, any conventionally known binder resin can be used, and preferred examples include ethyl cellulose, droxyethyl cellulose, ethyl hydroxy cellulose, and hydroxypropyl cellulose. , cellulose resins such as methylcellulose, cellulose acetate, cellulose acetate butyrate, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinylpyrrolidone,
Examples include vinyl resins such as polyacrylamide, polyesters, etc., and among these, cellulose-based, acetal-based, butyral-based, polyester-based, etc. are particularly preferred.

One embodiment of the present invention is characterized in that, when forming a dye layer from the above material, the dye layer contains a stabilizer that improves the stability of the dye.

The stabilizer used in the present invention includes light energy,
It is a chemical that can prevent the deterioration or decomposition of dyes by absorbing or blocking the deterioration or decomposition effects of dyes, such as thermal energy and oxidation effects.A specific example is oxidation inhibitors, which are conventionally known as additives for synthetic resins. agents, ultraviolet absorbers, and light stabilizers.

Antioxidants include phenolics, monophenols,
Examples include primary antioxidants such as bisphenol-based and amine-based antioxidants, and secondary antioxidants such as sulfur-based and phosphorus-based antioxidants, such as Sumilizer BBN-5, Su
milizer Bl-IT, SumilizerG
M, Sumilizer MB, Sumilize
r TPP-R (manufactured by Sumitomo Chemical), Yoshinox 4
25, Yoshinox SR (manufactured by Yoshitomi Pharmaceutical ■), Irg
It is commercially available under trade names such as anox-10111, Irganox-1222 (manufactured by Ciba Geigy), and Mark AO-40 (manufactured by Adeka Argus Chemical), and any of them can be used in the present invention.

In addition, examples of the ultraviolet absorber include salicylic acid-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based ultraviolet absorbers.
uvin P, Tinuvin 234, Tinuv
in 320. Tinuvin 326, Tinuv
in: 127, Tinuvin327 (manufactured by Ciba Geigy), Sumisorb 110, Sumis.

rb 140 (manufactured by Sumitomo Chemical), e+m1so
rb 10, emisorb II, emiso
RB 12, emisorb 13 (Chemipro Chemical ■
), Uvinul X-19, Llvinul
Ms-40 (manufactured by BASF), Tomisorb 100,
Tomisorb 600 (manufactured by Yoshitomi Pharmaceutical), Viosor
It is commercially available under trade names such as b-80 and Viosorb-90 (manufactured by Kyodo Yakuhin), and any of them can be used in the present invention.

Examples of light stabilizers include hindered amines, such as Sanol LS-770, Sanol LS-765, Sanol LS-774 (manufactured by Sankyo ■),
Sua+1sorb TM-061 (Sumitomo Chemical ■
They are commercially available under trade names such as (manufactured by), and any of them can be used in the present invention.

It is preferable that the stabilizer described below has the same thermal transferability (thermal transferability) as a foreign dye, for example, it does not contain a carboxyl group or a sulfonic acid group, and the molecular injection is
Preferably, it is 0 or less. If the molecule V exceeds 500, transferability may be insufficient.

The above stabilizers can be used alone or as a mixture, and the amount added is preferably in the range of 1 to 10 parts by weight per 100 parts by weight of the dye. If the amount added is too small, the stabilizing effect on the dye will be insufficient, and if it is too large, problems such as decreased transferability of the dye will occur, which is not preferable.

The dye layer of the thermal transfer sheet of the present invention is basically formed from the above-mentioned materials, but may also contain various conventionally known additives as required.

Preferably, such a dye layer is prepared by adding the above-mentioned sublimable dye, stabilizer, binder resin, and other optional components to a suitable solvent and dissolving or dispersing each component to prepare a paint or ink for forming the dye layer. This is formed by coating and drying this on the above base film.

The dye layer formed in this way has a thickness of 0.2 to 5.0 μm,
The thickness is preferably about 0.4 to 2.0 μm, and the sublimable dye in the dye layer accounts for 5 to 90% of the weight of the dye layer.
Suitably it is present in an amount of 10% to 70% by weight.

Another embodiment of the present invention is characterized in that, in the above embodiment, the dye layer is formed without incorporating the stabilizer into the dye layer, and the stabilizer is formed as a fl film on the surface of the dye layer.

The thin film of the stabilizer may be formed by dissolving the above-mentioned stabilizer in a solvent, coating it on the surface of the dye layer, and drying it, or
Preferably, a stabilizer is dissolved in a solvent together with the binder, applied to the surface of the dye layer, and dried to form a stabilizer layer. The ratio of stabilizer and binder used is not particularly limited, but for boat fishing, the weight ratio of stabilizer/binder dart is 1 part.
It is about /10 to 10/1. Also, J7 of the layer to be formed
The thickness is generally about 0.05 to 10 μm, and if it is too thin, the stabilizing effect of the transferred dye will be insufficient, and if it is too thick, it will impede the transferability of the dye, which is not preferable.

The thermal transfer sheet of the present invention as described above may be provided with a heat-resistant layer on its back surface in order to prevent the adverse effects of the heat of the thermal head.

The image-receiving sheet used to form an image using the thermal transfer sheet as described above may be of any type as long as its recording surface has dye-receptive properties for the above-mentioned dyes. In the case of paper, metal, glass, synthetic resin film or sheet, etc., which do not have a dye-receiving layer, a dye-receiving layer may be formed on at least one surface of a resin having excellent dye-receptivity. In addition, such a dye-receiving layer may contain solid waxes such as polyethylene wax, amide wax, and Teflon powder, which are known as release agents, fluorine-based or phosphate-based surfactants, silicone oil, etc. preferable.

One embodiment of the thermal transfer method of the present invention is a method using the thermal transfer sheet of the present invention, in which a stabilizer is simultaneously transferred to the dye transfer area (image forming area) at the same time as the dye is transferred. The image-receiving sheet used may be any conventionally known image-receiving sheet and is not particularly limited.

Another embodiment of the thermal transfer method of the present invention is characterized in that the stabilizer is transferred to the imaged areas of the image-receiving sheet before or after the transfer of the dye.

In this method, a stabilizer thermal transfer sheet can be created separately from the thermal transfer sheet, and the stabilizer can be transferred using this sheet in a transfer pattern similar to the dye transfer pattern before or after dye transfer. . In a further preferred embodiment, a stabilizer layer is formed in parallel with the dye layer of the thermal transfer sheet, e.g.
In the case of a color thermal transfer sheet in which three or four colors of yellow, magenta, and cyan (and black) are sequentially provided on a base sheet, a stabilizer layer is formed in addition to these dye layers, and the dye layer is Stabilizers can be transferred to the imaged areas before or after transfer.

As the means for applying thermal energy during thermal transfer used in the method of the present invention, any conventionally known applying means can be used. By controlling the recording time depending on the device, the intended purpose can be fully achieved by applying thermal energy of about 5 to 100 mJ/m.

(Effects) According to the present invention as described in F-F below, a dye stabilizer is included in the dye layer of a thermal transfer sheet, or a layer containing the stabilizer is formed on the surface of the dye layer, and the dye transfer is improved. By simultaneously transferring these stabilizers to the image forming area,
There is no need for the stabilizer to be present throughout the image-receiving sheet, and images with excellent light resistance and resistance to darkening and fading can be efficiently provided.

Further, according to the method of the present invention, by transferring a stabilizer to the image forming area before and after transferring the dye, it is possible to provide an image having excellent light resistance and resistance to darkening and fading as described above.

(Example) Next, the present invention will be explained in more detail by giving examples and comparative examples. In the text, parts or percentages are based on weight unless otherwise specified.

Example 1 An ink composition for forming a dye layer having the following composition was prepared and applied to a polyethylene terephthalate film (Lumirror 5^F53, manufactured by Toshi) with a thickness of 4 to 5 μm and whose back side was heat-resistant treated at a dry coating amount of 1. The thermal transfer sheet (1) of the present invention was obtained by coating and drying with a wire bar so as to obtain a coating film of 0.5 oz/g.

Disperse dye (Macrolex Yellow 6G, manufactured by Bayer AG) 5.5 parts Polyvinyl butyral resin (S-LEC BX-1゜Made by Block Chemical) 4.5 parts Antioxidant (
Susilizer BBM-5, manufactured by Sumitomo Chemical Co., Ltd.)
1.0 part methyl ethyl ketone/toluene (weight ratio 1/I)89.
0 parts Example 2 Antioxidant (Su
milizer BBM-5) 2.0 parts and ultraviolet absorber (Tinuvin P, manufactured by Ciba Geigy) 2.0 parts
Thermal transfer sheet (2) of the present invention was obtained in the same manner as in Example 1 except that the same procedure was used as in Example 1.

Example 3 Ink composition A for forming a dye layer having the following composition was prepared, and a polyethylene terephthalate film (Lumirror 5AF5:l, manufactured by Toshi) with a thickness of 4 to 5 μm was heat-resistant treated on the back side.
was coated with a wire bar and dried so that the dry coating amount was 1.0 g/ba, and the following composition B was further applied on the surface.
Dry coating in the same way q is 1. The thermal transfer sheet (3) of the present invention was obtained by coating and drying at a ratio of og/rn'.

Paper storage A Disperse dye (Macrolex Yellow 6G, manufactured by Bayer AG) 5.5 parts Polyvinyl butyral resin (S-LEC BX-1, manufactured by Mikki Kagaku) 4.5 parts Methyl ethyl ketone/toluene (weight ratio!/1) 90.0 parts Polyvinyl butyral resin for cosmetics (S-LEC BX-1, manufactured by Block Chemical Co., Ltd.) 6.0 parts Antioxidant (
Sumilizer BBM-5) 2.0 parts Ultraviolet absorber (Tinuvin P) 2.0
Part methyl ethyl ketone/toluene (weight ratio 1/1) 90
．． 0 parts Example 4 In Example 3, composition A and composition B were placed on the base film.
A thermal transfer sheet (4) of the present invention was obtained by coating and drying the same coating amount side by side with a width of 30 cm.

Comparative Example 1 Thermal transfer sheet (a) of Comparative Example was prepared in the same manner as in Example 1 except that the antioxidant 1F agent in Example 1 was not used.
I got it.

Reference Example 1 Synthetic paper (Yubo FRG-150, thickness 150 μm, manufactured by Oji Yuka Co., Ltd.) was used as a base film, and on one side of the paper, 5.0 g of a coating liquid with the following composition was applied using a bar coater when dry.
/m'' and dried to obtain a thermal transfer image-receiving sheet (A).

Polyester (Vylon 600, manufactured by Toyobo) 4.0 parts Vinyl chloride/vinyl acetate copolymer (#1000^, manufactured by Denki Kagaku Kogyo ■) 6.0 parts Amino-modified silicone (X-22-3050C, manufactured by Shin-Etsu Chemical) 0
．． 2 parts epoxy modified silicone (X-22-: 100E, manufactured by Shin-Etsu Chemical) 0.2 parts methyl ethyl ketone/toluene (weight ratio 1/I) 89.
6 copies Reference example 2 Synthetic paper (Yubo FRG-1513) as material film
, thickness 150 μm, manufactured by Oji Yuka Co., Ltd.), and a coating liquid with the following composition was applied to one side of the coating using a bar coater when drying.
A thermal transfer image-receiving sheet (B) was obtained by coating and drying at a rate of 0 g/ba.

Polyester (Vylon 600, manufactured by Toyobo) 4.0 parts Vinyl chloride/vinyl acetate copolymer (#1O00^, manufactured by Denki Kagaku Kogyo ■) 6.0 parts Amino-modified silicone (X~22-3050C1 manufactured by Shin-Etsu Chemical) 0
, 2 parts Epoxy modified silicone (X-22-300E, manufactured by Shin-Etsu Chemical) 0.2 parts Antioxidant (Sumilizer BBM-5)
1. 0 parts ultraviolet absorber (Tinuvin P)
1, 0 parts Methyl ethyl ketone/toluene (weight ratio l/!) 87.6 parts Examples 5 to 9 and Comparative Examples 2 to 3 The thermal transfer sheets of the present invention and comparative examples and the thermal transfer image-receiving sheets of reference examples described above were prepared, respectively. The dye layer and dye-receiving surface of
, Newly manufactured by Hitachi), recording was performed from the back side of the thermal transfer sheet with a thermal head at a printing energy of 90 mJ/mrn', and when the thermal transfer sheet of Example 4 was used, the thermal transfer sheet was further removed after image formation. The stabilizer was thermally transferred under the same conditions with a shift of 30 cm, and the results shown in Table 1 below were obtained. Note that the photofading rate of the print is the fading rate under JIS Class 3 irradiation conditions, and the darkness fading rate was compared by the fading rate after the recorded image was kept in a dry state at 70° C. for 24 hours. The fading rate is a value calculated using the following formula.

0D,. = Reflection density of printed matter immediately after printing 0, D, =
Reflection density of printed matter after storage at 70°C for 24 hours (hereinafter referred to as margin) F 1 -- Example 5 1/A 18.7 14.0 Example 6 2/A 13.5 13.3 Example 7
3/A 10.7 10.9 Example 8 4/
A 12.1 12.8 Example 9 4/B
9.8 10.1 Comparative Example 2 a/A 3
0.6 19.4 Comparative Example 3 a/B 19.
7 16.2 Example 10 Magenta (Disp
else Red 60), Shia? / (Solven
A three-color, field-sequential, multicolor thermal transfer sheet was prepared using a t Blue 63), and in the same manner as in Example 5, a full-color image with excellent light fastness and resistance to darkening and fading was obtained.

Example 11 Instead of the antioxidant in Example 1, Sum i I
1zer 0IIT, Sumilizer
GM, Sumilizer MB, Su
milizer TPP-R, Yoshinox 425, Yoshinox SR, Irganox-1081, lrga
nox-1222, Mark 80-0, Tinuvi
n 234, Tinuvin 320, Tin
uvin 326, Tinuvin 127, T
inuvin 327, Sumisorb
110, Sumisorb140, Ke+5iso
rb 1G, emisorb 11, emisor
b 12° emisorb l:l, 1Jvin
ul X-19, Uvinul Ms-40, Tomisorb 100, Tomisorb 600, V 1osorb-80
, Viosorb-90, Sanol LS-770. Sanol LS-765, Sanol LS-774, 5unis
orb TM-061 and other antioxidants, ultraviolet absorbers,
An image excellent in light fastness and resistance to darkening and fading was obtained in the same manner as in Example 5 except that a light stabilizer was used.

Claims (3)

[Claims] (1) A thermal transfer sheet having a dye layer formed on the surface of a base film, characterized in that a dye stabilizer is contained in the dye layer or on the surface thereof. (2) The thermal transfer sheet according to claim 1, wherein the stabilizer is an antioxidant, an ultraviolet absorber, or a light stabilizer with a molecular weight of less than 500. (3) The dye layer of the thermal transfer sheet with the dye layer formed on the surface of the base film and the receiving layer of the image receiving sheet with the dye receiving layer on the surface of the base film are stacked facing each other, and from the back side of the thermal transfer sheet, 1. A thermal transfer method performed by imagewise heating, characterized in that a dye stabilizer is transferred to an image forming area before, after, or simultaneously with dye transfer.