JPH06155935A - Thermal transfer sheet and production thereof - Google Patents

Abstract

PURPOSE:To obtain a high density thermal transfer image by forming a binder component constituting a dye layer from a cured material of compsn. containing isocyanate reactive cellulose, an acetal resin or the like and a polyisocyanate compd. CONSTITUTION:A thermal transfer sheet 1 is obtained by laminating a dye layer 3 containing a dye transferred to a thermal transfer image receiving sheet by heating on a base material sheet 2. In this case, the binder component constituting the dye layer 3 is formed from a cured material of a compsn. at least consisting of an isocyanate-reactive cellulose or acetal resin, at least one kind of resin selected from a group consisting of an isocyanate-reactive acetal resin, a vinyl resin, an acrylic resin, a phenoxy resin and a styrol resin and a polyisocyanate compd. By this constitution, a high density thermal transfer image and excellent storage stability are ensured without lowering printing quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer sheet, and more particularly to a thermal transfer suitable for forming a high-quality image on a thermal transfer image-receiving sheet by performing thermal printing according to image information with a thermal head or a laser. More particularly, the present invention relates to a thermal transfer sheet that enables high-density thermal transfer with low energy and has excellent stability during storage.

[0002]

2. Description of the Related Art Conventionally, as a method of forming an image in accordance with image information by using a thermal printing means such as a thermal head or a laser, a thermal transfer sheet provided with a sublimable dye layer having a property of transferring by heating. Is used in combination with a thermal transfer image-receiving sheet, while controlling the sublimable dye, the dye is transferred onto the thermal transfer image-receiving sheet to form a photographic image with gradation (image electronic See Journal No. 12, No. 1 (1983)). According to the above method, an image having continuous gradations can be obtained from a television signal by a simple process, and a device used at that time is not complicated, so that the method is attracting attention.

[0003]

However, it is difficult to form a high-density color image even if the conventionally used thermal transfer sheet is used as it is for thermal printing with a thermal head or the like. The main reasons are that the thermal sensitivity of the thermal transfer sheet is not high and the dye transfer ability of the thermal transfer image-receiving sheet is low. Among these drawbacks, those caused by the side of the thermal transfer image-receiving sheet are as follows: glass transition temperatures of -100 ° C to 20 ° C, islands made of synthetic resin having polar groups and independent of each other, and glass having a temperature of 40 ° C or higher. It has been found that a thermal transfer image-receiving sheet (Japanese Patent Application No. 58-135627) having a dye receiving layer formed in a sea-island shape with a sea portion made of a synthetic resin having a transition temperature can solve the problem. The one caused by the side has not been solved yet.

This is because in the conventional method for printing on cloth or the like,
For example, the transfer and dyeing of the dye can be achieved by heating at 200 ° C. for about 1 minute, while the heating by the thermal head is performed at about 400 ° C. for several msec. The reason is that it is short and short. Since the present inventors heat-print with a thermal head or the like to form a color photographic image, a thermal transfer image-receiving sheet, especially the above-mentioned Japanese Patent Application No. 58-13.
As a result of various studies to obtain a thermal transfer sheet suitable for use in combination with the thermal transfer image-receiving sheet of Japanese Patent No. 5627, the following facts were found.

That is, in a commonly used thermal transfer sheet, the dye is in a state of being dispersed in a binder resin in a granular form. To heat the dye molecules in such a state to sublimate Since it has to break down the interaction and further give thermal energy exceeding the interaction with the binder resin to the dye molecule to sublimate and dye it on the thermal transfer image-receiving sheet, it requires high energy and high density coloring. When the dye is contained in a high proportion with respect to the binder resin to obtain an image, although a high-concentration image can be obtained to some extent, the adhesive force between the dye layer of the thermal transfer sheet and the base sheet becomes weak. Therefore, if the thermal transfer sheet is overlaid with the thermal transfer image receiving sheet and printed with a thermal head, etc., and then the thermal transfer sheet is peeled off, not only the dye but also the entire dye layer is exposed. In addition, the phenomenon of peeling is likely to occur, and the dye is expensive in price. From the standpoint of OA equipment and home use, it is economical to add more dye than necessary. Is also disadvantageous.

On the other hand, if the dye can be held in the binder resin in the form of a molecular dispersion instead of a granular form, the thermal sensitivity is improved because there is no interaction within the crystal as in the case of being dispersed in the form of particles. There is expected. However, even if such a state is simply achieved in the binder resin, a practical thermal transfer sheet cannot be obtained. That is, the thermally sublimable dye molecule has a relatively small molecular weight of about 150 to 550 and easily moves in the binder resin forming the dye layer. Therefore, for example, when a binder resin having a low glass transition temperature (Tg) is used, development occurs in which the dye agglomerates and projects in the dye layer over time, and as a result, the dye is dispersed in the form of particles as described above. Or the dye bleeds out on the surface of the dye layer, so that the pressure between the thermal head and the platen (platen) at the time of recording causes the dye to adhere around the heated area. This causes scumming and significantly deteriorates the image quality.

Further, the glass transition temperature (T
Even if g) is high, dye molecules cannot be retained unless the molecular weight of the binder resin is large to some extent. Furthermore, even if a dye is molecularly dissolved in a binder resin having a high glass transition temperature (Tg) and a relatively large molecular weight, the dye molecule and the binder resin are required to be stable with time. Affinity of is required. In view of these points, various types of thermal transfer sheets have been conventionally proposed for the purpose of improving image quality. For example, JP-A-6
As described in JP-A-3-151484, by using a specific polyvinyl acetoacetal resin as a binder resin component in the dye layer ink, it is known that print quality and temporal stability can be improved. ing.

However, these conventional thermal transfer sheets are not always sufficiently satisfactory in terms of sensitivity. Further, ethyl hydroxyethyl cellulose and ethyl cellulose are known as binder resins having excellent sensitivity, but these binder resins have a drawback in that the storage stability of the thermal transfer sheet is inferior in terms of dye aggregation / precipitation prevention properties. Generally, as a condition required for a thermal transfer sheet, the storability of the thermal transfer sheet itself is important as well as various characteristics relating to image quality such as printing sensitivity and resolution. However, printing sensitivity and storability tend to cancel each other out, and it is difficult to improve both of these characteristics. Although it is possible to partially improve these characteristics by mixing a binder resin, in general, separation or protrusion of the resin or dye is likely to occur, and stable performance cannot be obtained. Therefore, the present invention has been made in view of the above-mentioned points, and it is possible to provide a thermal transfer sheet which is capable of high-concentration thermal transfer with low energy and is excellent in storage stability without degrading printing quality. Has an aim.

[0009]

The above object can be achieved by the present invention described below. That is, the present invention is a thermal transfer sheet comprising a base sheet, and a dye layer containing a dye that is transferred by heating and transferred onto a thermal transfer image-receiving sheet is laminated on the base sheet, and a binder component constituting the dye layer. Is a group consisting of at least one of isocyanate-reactive cellulose or isocyanate-reactive acetal resin, and isocyanate-reactive acetal resin, isocyanate-reactive vinyl resin, isocyanate-reactive acrylic resin, isocyanate-reactive phenoxy resin and isocyanate-reactive styrene resin. A thermal transfer sheet comprising a cured product of a composition containing at least one resin selected from the above and a polyisocyanate compound, and a method for producing the same.

[0010]

By using a specific cross-linking binder resin as the binder component constituting the dye layer, it is possible to provide a thermal transfer sheet capable of high-concentration thermal transfer with low energy and excellent in storage stability. Further, according to the production method of the present invention, when the dye layer is formed, the binder used is crosslinked to such an extent that it is soluble in a solvent, and thus the coating suitability of the coating liquid during the formation of the dye layer is good, The phase separation of the plurality of binder resins does not occur, and further, the dye does not aggregate or separate in the coating liquid, and the dye layer uniformly containing the dye is easily formed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below with reference to the preferred embodiments shown in the drawings. The thermal transfer sheet 1 according to the present invention, as shown in FIG.
It is configured by providing the dye layer 3 on the top. The base sheet 2 may be condenser paper, polyester film, polystyrene film, polysulfone film, polyimide film, polyvinyl alcohol film, cellophane, etc., aramid film, polyetherimide film, polyetheretherketone film, polyparbanic acid film, etc. Is used, and the thickness thereof is 1.5 to 50 μm, preferably 2 to 9 μm. Condenser paper is used when price and heat resistance in the untreated state are required among these papers and films, while it has mechanical strength and can be used when handling thermal transfer sheets or in thermal printers. A polyester film is preferably used when it is important that it does not break when running and that the surface is smooth.

The dye layer 3 is mainly composed of a dye and a specific binder component. The dye used in the present invention is a dye which is melted, diffused or sublimated by heat to migrate, and a disperse dye is particularly preferably used. These dyes have a molecular weight of about 150 to 650 and are selected in consideration of sublimation (melting) temperature, hue, light resistance, ink formation, solubility in a binder resin, etc., and are generally selected. , Diarylmethane series, triarylmethane series,
Representative of thiazoles, methines such as merocyanine, indoaniline, acetophenone azomethine, pyrazoloazomethine, imidazole azomethine, imidazoazomethine, azomethine typified by pyridone azomethine, xanthine, oxazine, dicyanostyrene, tricyanostyrene Cyanomethylene, thiazine, azine, acridine, benzeneazo, pyridoneazo,
Thiophene azo, isothiazole azo, pyrrole azo,
Heterocyclic azo type represented by pyrazole azo, imidazole azo, thiadiazole azo, triazole azo, disazo, spiro dipyran type, indolino spiro pyran type,
Typical dyes are fluoran dyes, rhodamine lactam dyes, naphthoquinone dyes, anthraquinone dyes, and quinophthalone dyes. Specifically, the following dyes can be preferably used. C. I. (Color Index) Yellow 51, 3, 54, 79, 60, 23, 7, 141, 20
1, 231; C.I. I. Disperse Blue 24, 56,
14, 301, 334, 165, 19, 72, 87, 2
87, 154, 26, 254; C.I. I. Disperse Threads 135, 146, 59, 1, 73, 60, 167;
C. I. Disperse Violet 4, 13, 26, 3
6, 56, 31; C.I. I. Disperse Orange 14
9; C.I. I. Solvent Violet 13; C.I. I. Solvent Black 3; C.I. I. Solvent Green 3;
C. I. Solvent Yellow 56, 14, 16, 29;
C. I. Solvent Blue 70, 35, 63, 36, 5
0, 49, 111, 105, 97, 11; C.I. I. Solvent Red 135, 81, 18, 25, 19, 23,
24, 143, 146, 182, etc.

More specifically, for example, 3,3'-diethyloxathiacyanine iodide astrazone pink FG (manufactured by Bayer, CI48015),
2,2'-carbocyanine (C.I.808), Astraphylloxin FF (C.I.48070), Astrazone Yellow 7GLL (C.I. Basic Yellow 21), Eisen Catillon Elo 3GLH (Hodogaya Kagaku) C.I.48055), Eisen Catillon Red 6BH (C.I.48020), and other methine (cyanine) basic dyes such as monomethine, dimethine, or trimethine; auramine (C.I.655). ) And the like diphenylmethane-based basic dyes; malachite
Green (C.I. 42000), Brilliant Green (C.I. 42040), Magenta (C.I. 4)
2510), metal violet (C.I.
5), crystal violet (C.I.
5), methyl green (C.I.684), Victoria Blue B (C.I.44045) and other triphenylmethane-based basic dyes; Pyronin G (C.I.739),
Rhodamine B (C.I.45170), Rhodamine 6G
(C.I.45160) and other xanthene-based basic dyes;
Acridine Yellow G (C.I.785), Leonine AL (C.I.46075), Benzoflavin (C.I.
I. 791), Affine (CI.46045) and other acridine-based basic dyes; Neutral Red (C.I.
I. 50040), Astrazone Blue BGE / x
125% (CI.51005), methylene blue (CI.52015) and other quinone imine-based basic dyes; and other basic dyes such as anthraquinone-based basic dyes having a quaternary ammonium group .

As cyan dyes, Kayaset Blue 714 (Nippon Kayaku, Solvent Blue 63), Foron Brilliant Blue SR (Sand, Disperse Blue 354), Waxolin AP-FW (ICI, Solvent Blue) 36), as a magenta dye, MS-R
EDG (manufactured by Mitsui Toatsu, Disperse Red 60), Macrolex Red Vio Red R (manufactured by Bayer, Disperse Violet 26), as yellow dye, Foron Brilliant Yellow S-6GL (manufactured by Sand, Disperse Yellow 231), macro Rex yellow 6
G (manufactured by Bayer, Disperse Yellow 201), and those having the following structural formulas are also included.

[0015]

[Chemical 1] These dyes can be used in the form as they are, or in the form obtained by subjecting these dyes to an alkali treatment, and a counter ion exchanger or leuco form of these dyes can also be used. When a leuco dye or the like, which is normally colorless or light-colored, is used, it may be incorporated in the developer on the thermal transfer image-receiving sheet.

Further, JP-A Nos. 59-78895 and 60-
28451, 60-28453, 60-535.
No. 64, No. 61-148096, No. 60-23929.
No. 0, No. 60-31565, No. 60-30393,
60-53565, 60-27594, 61
-262191, 60-152563, 61-
244595 and 62-196186 and sublimation yellow dyes described in International Publication WO92 / 05032.
No. 60-223862, No. 60-28452, No. 6
0-31563, 59-78896, 60-3
No. 1564, No. 60-30391, No. 61-2270
No. 92, No. 61-227091, No. 60-30392.
No. 60-30394, No. 60-131293,
61-222793, 60-159091, 61-262190, US Pat. No. 4,698,651 and Japanese Patent Application No. 62-220793, US Pat.
Sublimable magenta dyes described in 9,365, JP-A-59
-78894, 59-227490, 60-1
No. 51098, No. 59-227493, No. 61-24
No. 4594, No. 59-227948, No. 60-131.
No. 292, No. 60-172591, No. 60-1510.
No. 97, No. 60-131294, No. 60-21726.
No. 6, No. 60-31559, No. 60-53563,
61-255897, 60-239289, 61-22993, 61-19396, 61-61.
268493, 61-35994, 61-31
No. 467, No. 61-148269, No. 61-4989.
No. 3, No. 61-57651, No. 60-239291.
No. 60-239292, 61-284489.
No. 62-191191 and Japanese Patent Application No. 62-17
Sublimable cyan dyes described in publications such as 6625, US Pat. No. 5,079,365 and the like are also preferably used. In the present invention, the general formulas of dyes that are particularly preferable are illustrated.

[0017]

[Chemical 2]

[0018]

[Chemical 3]

[0019]

[Chemical 4]

[0020]

[Chemical 5]

[0021]

[Chemical 6]

In the above general formula, R, X and Y represent the following substituents. R ₁ and R _{2 A} substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group or a substituted or unsubstituted aralkyl group. R ₃ substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkylcarbonylamino group, substituted or unsubstituted alkylsulfonylamino group, substituted or unsubstituted alkylaminocarbonyl group, substituted or An unsubstituted alkylaminosulfonyl group or a halogen atom. R ₄ substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted alkylaminocarbonyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkyl group, substituted or unsubstituted cycloalkyl group, heterocyclic group or Halogen atom. R ₅ substituted or unsubstituted alkyl group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted alkylaminocarbonyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkylaminosulfonyl group, substituted or non-substituted Substituted cycloalkyl group, cyano group, nitro group or halogen atom.

R _{6 A} substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted amino group, a substituted or unsubstituted cycloalkyl group, a cyano group, a nitro group or a halogen atom. R _{7 A} substituted or unsubstituted alkyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkoxycarbonyl group or a halogen atom. R _{8 A} substituted or unsubstituted aryl group, aromatic heterocyclic group, cyano group, nitro group, halogen atom or other electron withdrawing group. R ₉ CONHR ₁₀ , SO ₂ NHR ₁₀ , NHCOR ₁₁ ,
NHSO ₂ R ₁₁ or a halogen atom. R _{10 A} substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted aromatic heterocyclic group.

R _{11 A} substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aromatic heterocyclic group. R _{12 A} substituted or unsubstituted alkyl group. R ₁₃ amino group or hydroxyl group. X halogen atom. A Y- substituted or unsubstituted aryl group, a substituted or unsubstituted aromatic heterocyclic group.

Specific examples of preferable dyes will be given below.

[Chemical 7]

[0026]

[Chemical 8]

[0027]

[Chemical 9]

The binder resin used in the present invention is at least one of isocyanate-reactive cellulose or isocyanate-reactive acetal resin, and isocyanate-reactive acetal resin, isocyanate-reactive vinyl resin, isocyanate-reactive acrylic resin, isocyanate-reactive phenoxy resin. A resin and a cured product of a composition containing at least one resin selected from the group consisting of an isocyanate-reactive styrene resin and a polyisocyanate compound, and this resin may be another binder resin as long as the object of the present invention is not impaired. Can be used together in an amount of 50% by weight or less based on the entire binder resin. The isocyanate-reactive cellulose used in the present invention can be represented by the following general formula.

[Chemical 10] R: represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, an acyl group or an aralkyl group. Cellulose essential as a binder component in the present invention has a number of hydroxyl groups per glucose unit of 0.1 to 1.5,
It is desirable that it is 0.3 to 1.0 in order to improve the storability and printing characteristics of the thermal transfer sheet, and it is also desirable from the reaction with the polyisocyanate compound.

The acetal resin used in the present invention can be obtained by acetalizing polyvinyl alcohol and can be generally represented by the following general formula.

Embedded image General formula A R: hydrogen atom, alkyl group, cycloalkyl group, aryl group, aralkyl group or heterocyclic group When polyvinyl alcohol (PVA) is acetalized, it is difficult to completely acetalize PVA as shown in the above formula. Yes, some acetyl groups and hydroxyl groups inevitably remain. According to the research conducted by the present inventors, it has been clarified that a resin having an acetalized portion is particularly excellent in improving both the storability and the printing characteristics of the thermal transfer sheet in a specific amount range. That is, in the polyvinyl acetal resin, the weight% of the acetal portion thereof is 50% by weight or more, preferably 6% by weight with respect to the total amount of the polyvinyl acetal resin.
2% by weight or more, more preferably 70% by weight or more is desirable in order to improve the storability and printing characteristics of the thermal transfer sheet. From the viewpoint of reactivity with the polyisocyanate compound, the weight% of the hydroxyl group portion is It is desirable that the amount is 1% or more, preferably 8% or more based on the total amount of the polymer.

The vinyl resin used in the present invention can be represented by the following general formula.

Embedded image General formula B R: hydrogen atom, hydroxyalkyl group R ': hydrogen atom, alkyl group, aryl group, halogen atom A resin having a vinyl chloride moiety in a specific amount range is excellent in improving both the storage stability and the printing characteristics of the thermal transfer sheet. There is. That is, the weight% of the vinyl chloride portion is 50% by weight or more, preferably 70% or more, more preferably 78% or more with respect to the total amount of the vinyl resin, and the weight% of the hydroxyl group is 1% from the reaction with the polyisocyanate compound. % Or more, preferably 8% or more.

The acrylic resin used in the present invention can be represented by the following general formula.

Embedded image General formula C R: hydrogen atom, alkyl group, cycloalkyl group, aryl group, aralkyl group, hydroxyalkyl group, bridged ring compound R ': hydrogen atom, alkyl group, aryl group, halogen atom R ": alkyl group, cycloalkyl group, substituted May be aryl group, heterocyclic group% by weight of hydroxyl group from reaction with polyisocyanate compound
Is 1% or more, preferably 3% or more of the total amount of the acrylic resin. Further, from the viewpoint of improving both the storability and printing characteristics of the thermal transfer sheet, the weight% of the maleimide portion is 10% or more of the total amount of the acrylic resin, preferably 18
% Or more, or the content of isobonyl acrylate in the acrylic ester portion is 15% by weight of the total amount of the acrylic resin.
It is desirable that the amount is at least 20% by weight, preferably at least 20% by weight.

The styrene resin used in the present invention can be represented by the following general formula.

Embedded image General formula D R: hydrogen atom, alkyl group, aryl group, halogen atom R ': hydrogen atom, alkyl group, allyl group, halogen atom R ": hydrogen atom, alkyl group, cycloalkyl group, aryl group, aralkyl group, hydroxyalkyl group, Crosslinked ring compound R ′ ″: hydrogen atom, alkyl group From the viewpoint of reactivity with the polyisocyanate compound, the weight% of hydroxyl groups is preferably 1% or more, and more preferably 3% or more of the total amount of the styrene resin. Further, from the viewpoint of improving both the storability and the printing characteristics of the thermal transfer sheet, it is desirable that the weight% of the styrene or styrene-acrylonitrile portion is 50% or more, preferably 65% or more of the total amount of the acrylic resin.

The phenoxy resin used in the present invention can be represented by the following general formula.

Embedded image General formula E R: hydrogen atom, alkyl group, halogen atom Y: saturated hydrocarbon group From the viewpoint of reactivity with the polyisocyanate compound, the weight% of the hydroxyl group is 1% or more, preferably 3% or more of the total amount of the phenoxy resin. desirable.

As the polyisocyanate compound used in the present invention, various diisocyanates, triisocyanates and polyisocyanates can be used. For example, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, 1,5 -Naphthylene diisocyanate, 1,4-tetramethylene diisocyanate, hexamethylene diisocyanate, isopropylidene cyclohexyl diisocyanate, isophorone diisocyanate, triphenylmethane triisocyanate and burette, trimethylolpropane adduct, isocyanurate trimer and the like. . The amount of these polyisocyanate compounds to be used is preferably such that the amount of isocyanate groups is 0.01 to 4 times, more preferably 0.05 to 3 times the amount of active hydrogen in the resin. When the amount of the isocyanate groups is less than 0.01 times the amount of active hydrogen in the resin, the resin or dye is likely to be separated or broken, and the stable coating performance of the ink cannot be obtained. On the other hand, when the amount is more than 4 times, the number of cross-linking points increases, causing a problem of gelation of the ink or deterioration of solvent solubility.

The ratio of the dye contained in the dye layer depends on the sublimation (melting) temperature of the dye and the covering power (color rendering) in the color-developed state. The (dye / binder resin ratio) is preferably 0.3 or more, more preferably 0.3 to 3.0.
And most preferably 0.55 to 2.5. If the dye / binder resin ratio is less than 0.3, the image quality such as print density and heat sensitivity is not preferable, while 3.0
If it exceeds, the adhesiveness to the film and the storability of the thermal transfer sheet tend to be deteriorated. To provide the dye layer 3 on the base sheet 2, a dye and a binder resin are dissolved with a suitable solvent to form a dye layer ink, which is applied on the base sheet 2 by an appropriate printing method or coating method. It may be dried. In the formation of an ink, the binder component and the polyisocyanate compound ink may be in an unreacted state, may be in a partially reacted state, or may be in a sufficiently reacted state, but in any case, they are dissolved in the ink solvent. It is preferable to allow the reaction to some extent. Further, the dye is preferably in a substantially dissolved state in the binder resin. If desired, any additive may be added to the dye layer ink.

The basic constitution of the thermal transfer sheet of the present invention is as described above. However, when the surface of the substrate sheet is directly heated by a contact type heating means such as a thermal head, it is shown in FIG. Similarly, by providing the lubricant layer 4 containing a lubricant such as wax or a release agent on the side of the base sheet 2 on which the dye layer 3 is not provided, the heating means such as a thermal head and the base sheet are combined. It is possible to prevent fusion and improve slipperiness. The thermal transfer sheet of the present invention may be in the form of a single sheet cut into a required size, may be in the form of a continuous sheet or in the form of a roll, and may be in the form of a tape having a narrow width. When the dye layer 3 is provided on the base material sheet 2, the dye layer ink containing the same dye may be applied to the entire surface of the base material sheet 2, but in some cases, different dyes may be used. You may form the several dye layer ink containing in each area | region where the surface of the base material sheet 2 differs. For example, a thermal transfer sheet in which a black dye layer 5 and a red dye layer 6 are laminated in parallel on a base material sheet 2 as shown in FIG. 3, or a yellow dye layer 7 as shown in FIG. It may be a thermal transfer sheet in which the red dye layer 8, the blue dye layer, and the black dye layer 10 are repeatedly provided on the base material sheet 2.

By using such a thermal transfer sheet provided with a plurality of dye layers having different hues, there is an advantage that a multicolor image can be obtained by one thermal transfer sheet. The thermal transfer sheet can be conveniently used by forming a perforation or providing a detection mark or the like for detecting the positions of areas having different hues. The thermal transfer sheet and the optional thermal transfer image-receiving sheet of the present invention configured as described above are prepared, for example, as shown in FIG. 5, the dye layer 3 of the thermal transfer sheet 1 and the dye-receiving layer 13 on the base sheet 12 of the thermal transfer image-receiving sheet. And the dye in the dye layer 3 by applying heat energy corresponding to image information to the interface between the dye layer 3 and the dye receiving layer 13 by a heat applying means such as a thermal head 14. 13 and the desired image can be formed in the dye receiving layer 13.

As a heat source for giving heat energy, in addition to the thermal head 14, laser light, infrared flash,
A known one such as a hot pen can be used. The thermal energy may be applied from the thermal transfer sheet side, from the thermal transfer image receiving sheet side or from both sides, but from the viewpoint of effective utilization of thermal energy, the thermal transfer sheet side is preferred. . However, when the heat energy is applied from the thermal transfer image receiving sheet side, the applied heat energy is controlled to express the gradation of the light and shade of the image,
Alternatively, it is preferable in the sense that the dye is promoted to diffuse on the thermal transfer image-receiving sheet to more reliably represent the continuous tone of the image, and in the method of applying heat energy from both sides, the advantages of the both methods are simultaneously obtained. You can enjoy it.
When the thermal head 14 is used as a heat source for applying heat energy, the applied heat energy can be changed continuously or in multiple steps by modulating the voltage or pulse width applied to the thermal head.

When laser light is used as a heat source for giving heat energy, the heat energy to be given can be changed by changing the light quantity of the laser light or the irradiation area. Further, if a dot generator with a built-in acousto-optic element is used, it is possible to give heat energy according to the size of the halftone dot. When using a laser beam, the thermal transfer sheet and the thermal transfer image-receiving sheet may be sufficiently adhered to each other, and the surface irradiated with the laser beam may be colored black, for example, in order to improve absorption of the laser beam. It is good to do it. Alternatively, if a substance that absorbs non-sublimable laser light and converts it into heat is added to the dye layer 3, the heat transfer to the dye is performed more efficiently and the resolution of the image is increased. When an infrared flash lamp is used as a heat source for giving heat energy, it may be carried out in the same manner as in the case of using a laser beam, or through a pattern or a halftone dot pattern which continuously expresses the shade of an image such as black. It may be carried out, or may be carried out by combining a black colored layer on one surface with a negative pattern corresponding to the negative of the above pattern.

When heat energy is applied to the interface between the dye layer and the dye receiving layer as described above, the dye in the dye layer is transferred to and received by the dye receiving layer 13 in an amount corresponding to the applied heat energy. To form a desired image. By the thermal transfer recording as described above, the dye corresponding to the thermal energy is thermally transferred to the dye receiving layer to record an image of one color. However, the above method can be performed by replacing the thermal transfer sheet, for example,
It is also possible to form a photographic color image composed of each color by sequentially replacing the yellow, red, indigo, and, if necessary, black thermal transfer sheets and performing thermal transfer according to each color. Instead of using the thermal transfer sheet of each color as described above, a thermal transfer sheet having areas formed by separately coating each color as shown in FIG. 4 is used. First, the yellow color separation image is thermally transferred using the yellow area. Then, thermal transfer is performed using the red area of the thermal transfer sheet, and thereafter, the method of thermally transferring the color separation images of yellow, red, indigo, and, if necessary, black by repeating thermal transfer in sequence is adopted. There is an advantage that the replacement of is unnecessary. The quality of the obtained image can be improved by appropriately adjusting the size of the heat source used to apply the heat energy, the adhesion between the heat transfer sheet and the heat transfer image receiving sheet, and the heat energy.

By using the thermal transfer sheet of the present invention in combination with a thermal transfer image receiving sheet, printing using various printers of thermal printing system, facsimile, or printing of photographs by magnetic recording system or printing from a television screen. It can be used for creating etc. For example, one screen of the received television is stored in a recording medium such as a magnetic tape or a magnetic disk as a signal of each color separation pattern of yellow, red, indigo, and black if necessary,
A signal of each stored color separation pattern is output, and thermal energy corresponding to this signal is applied to the superposed body of the thermal transfer sheet and the thermal transfer image receiving sheet by the above-mentioned heat source such as a thermal head, and the thermal transfer is sequentially performed for each color. Then, the screen of the television can be reproduced as a sheet-shaped hard print. When a combination of a thermal transfer image-receiving sheet and the thermal transfer sheet of the present invention is used to print out such a television screen, a white dye-receiving layer alone or a colorless and transparent dye-receiving layer is usually used as the thermal transfer image-receiving sheet. It is convenient to form a reflection image by using a sheet backed by a base sheet such as paper or a white dye receiving layer backed by a base sheet such as paper. still,
The same thing as above can be done by operating a computer
This can be done when using a combination of characters, figures, symbols and colors formed on the screen as well as a graphic pattern as an original picture, and the original picture is a fixed image such as a painting, a photograph, a printed matter or a person, a still life. When it is an actual object such as a landscape, an image can be formed in the same manner as described above by using an appropriate means such as a video camera as a medium. Further, when generating signals of each color separation pattern from the original image, an electronic plate making machine (color scanner) used for photolithography of printing may be used.

[0042]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the text, parts and% are based on weight unless otherwise specified. Examples 1 to 88 A dye layer ink having the following composition was prepared, and applied to a 6 μm-thick polyethylene terephthalate film having a heat-treated back surface so that the dry coating amount was 1.0 g / m ² and dried. A thermal transfer sheet of the present invention was obtained. Ink composition Dye of the specific example a part Cellulose-based binder resin (I) or acetal-based binder resin (described in the table below) b ₁ part Binder resin (II) of the general formulas A to D (described in the table below) b ₂ part polyisocyanate compound (ratio of isocyanate groups to the amount of resin active hydrogen) (described in the following table) c methylethylketone _{(100-a-b 1 -b} 2) / 2 parts of toluene (100-a-b ₁ -b ₂ ) / 2 parts However, ethyl cellulose N-200 (EC) and ethyl hydroxyethyl cellulose High (EHEC) used as the binder resin (I) are manufactured by Hercules, and the acetal resin is S-REC KS-5 (manufactured by Sekisui Chemical Co., Ltd.). The polyisocyanate compound is Desmodur T-80 (TDI), made by Nippon Polyurethane,
Sumidule 445 (MDI), manufactured by Sumitomo Bayer.

When the dye is insoluble in the solvent in the above composition, DMF, dioxane, chloroform or the like was appropriately used as the solvent. Next, synthetic paper (Yupo FPG # 150, manufactured by Oji Yuka) was used as the base sheet, and one side was coated with a coating solution having the following composition at a rate of 10.0 g / m ² when dried. The film was dried at 100 ° C. for 30 minutes to form a dye receiving layer to obtain a thermal transfer image receiving sheet. Polyester binder resin (Vylon 200, manufactured by Toyobo) 11.5 parts Vinyl chloride / vinyl acetate copolymer (VYHH, manufactured by UCC) 5.0 parts Amino-modified silicone (KF-393, manufactured by Shin-Etsu Chemical Co., Ltd.) 1.2 parts Epoxy-modified Silicone (X-22-343, manufactured by Shin-Etsu Chemical Co., Ltd.) 1.2 parts Methyl ethyl ketone / toluene / cyclohexane (weight ratio 4: 4: 2) 102.0 parts Thermal transfer recording test The thermal transfer sheet of the present invention and the thermal transfer image-receiving described above. The sheet is superposed with the dye layers and the dye receiving surface facing each other, and a head applied voltage of 11 V and a printing time of 10 msec from the back surface of the thermal transfer sheet. Recording was carried out with a thermal head under the conditions described above, and the results shown in Tables 1-8 below were obtained. Storage test The above-mentioned thermal transfer sheet of the present invention was stored at 60 ° C for 60 hours. The surface condition of the dye layer after storage was observed, and the storage stability was determined according to the following criteria. ○: No deposition of dye was observed. B: Some precipitation of dye was observed. ×: A large amount of deposition of dye was observed. Density measurement The optical density meter R was used to measure the reflection density of the recorded thermal transfer image-receiving sheet.
It measured using D-918 (made by a Macbeth company).

Comparative Examples 1 to 23 The results shown in Table 9 below were obtained in the same manner as in Examples except that the materials for forming the dye layer were changed to the following. Ink composition Dye of the specific example (described in the table below) a part Binder resin (described in the table below) b part Methyl ethyl ketone (100-ab) / 2 parts Toluene (100-ab) / 2 parts

[0045]

[Table 1] Binder resin = general formula A

[0046]

[Table 2] Binder resin = general formula A

[0047]

[Table 3] Binder resin = general formula B * ¹ : -CO ₂ C ₂ H ₄ OH

[0048]

[Table 4] Binder resin = general formula C

[0049]

[Table 5] Binder resin = general formula C

[0050]

[Table 6] Binder resin = general formula C (continued from Tables 4 to 5)

[0051]

[Table 7] Binder resin = general formula D

[0052]

[Table 8] Binder resin = general formula D (continued from Table 7)

[0053]

[Table 9] Binder resin = general formula E (continued from Table 7)

[0054]

[Table 10]

[0055]

[Effect] According to the present invention as described above, by adopting a specific cross-linking binder resin as a binder component constituting the dye layer, a thermal transfer sheet capable of high-concentration thermal transfer with low energy and excellent in storage stability. Can be provided. Further, according to the production method of the present invention, when the dye layer is formed, the binder used is crosslinked to such an extent that it is soluble in a solvent, and thus the coating suitability of the coating liquid during the formation of the dye layer is good, The phase separation of the plurality of binder resins does not occur, and further, the dye does not aggregate or separate in the coating liquid, and the dye layer uniformly containing the dye is easily formed.

[0056]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a thermal transfer sheet of the present invention.

FIG. 2 is a sectional view of the thermal transfer sheet of the present invention.

FIG. 3 is a perspective view of a thermal transfer sheet of the present invention.

FIG. 4 is a perspective view of a thermal transfer sheet of the present invention.

FIG. 5 is an explanatory view illustrating a method for transferring using the thermal transfer sheet of the present invention.

[Explanation of symbols]

 1 ... Thermal transfer sheet 2 ... Base sheet 3 ... Dye layer 11 ... Heat transfer sheet 12 ... Base sheet 13 ... Receiving layer 14 ... Thermal head 15 ... Platen roll

Claims (8)

[Claims] 1. A thermal transfer sheet comprising a substrate sheet and a dye layer containing a dye which is transferred by heating and transferred onto a thermal transfer image-receiving sheet, is laminated, wherein a binder component constituting the dye layer is , At least one of isocyanate-reactive cellulose or isocyanate-reactive acetal resin, and a group consisting of isocyanate-reactive acetal resin, isocyanate-reactive vinyl resin, isocyanate-reactive acrylic resin, isocyanate-reactive phenoxy resin and isocyanate-reactive styrene resin. A thermal transfer sheet comprising a cured product of a composition containing at least one selected resin and a polyisocyanate compound. 2. The thermal transfer sheet according to claim 1, wherein the number of hydroxyl groups per glucose unit of the isocyanate-reactive cellulose is 0.1 to 1.5. 3. The weight percentage of the hydroxyl group of the isocyanate-reactive acetal resin is 1% to the total amount of the polymer.
The thermal transfer sheet according to claim 1, wherein the thermal transfer sheet is 45%, and the weight% of the acetal portion is 50% or more based on the total amount of the polymer. 4. The weight percentage of the hydroxyl group portion of the isocyanate-reactive vinyl resin is 1% to 35 with respect to the total amount of the polymer.
%, And the weight% of the vinyl chloride portion is 50% or more based on the total amount of the polymer, and the thermal transfer sheet according to claim 1. 5. The weight percentage of the hydroxyl group portion of the isocyanate-reactive acrylic resin is 1% to 2 with respect to the total amount of the polymer.
The thermal transfer sheet according to claim 1, which is 5%. 6. The weight percentage of the hydroxyl group portion of the isocyanate-reactive styrene resin is 1% to the total amount of the polymer.
The thermal transfer sheet according to claim 1, which is 30%. 7. The thermal transfer sheet according to claim 1, wherein the weight% of the hydroxyl group portion of the isocyanate-reactive phenoxy resin is 1% or more based on the total amount of the polymer. 8. A method for producing a thermal transfer sheet, which comprises forming a dye layer containing a dye which is transferred by heating and transferred onto a thermal transfer image-receiving sheet on a substrate sheet, wherein at least isocyanate-reactive cellulose or isocyanate is used. At least one selected from the group consisting of one kind of reactive acetal resin and isocyanate-reactive acetal resin, isocyanate-reactive vinyl resin, isocyanate-reactive acrylic resin, isocyanate-reactive phenoxy resin, and isocyanate-reactive styrene resin.
A method for producing a thermal transfer sheet, which comprises applying a composition containing a resin of one kind and a polyisocyanate compound or a reaction product thereof and a coating solution containing the dye to the surface of a substrate sheet and drying the composition.