JPH04234693A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To obtain a thermal transfer sheet capable of producing images in high density and are excellent in various fastnesses by making a dye-bearing layer thereof contain dye expressed by a specified general formula. CONSTITUTION:A thermal transfer sheet is made up of a base sheet and a dye-bearing layer that is formed on one side of the said base sheet. The aforementioned dye-bearing layer is made to contain the dye expressed in a formula I. {in the said formula, R1, R2 represent substituent or nonsubstituent alkyl group, and at least one of the above two is a group including heterocycle or aromatic ring. R3 represents substituent or unsubstituent C1-C7 alkyl group or the like, R4 represents unsubstituent low alkyl group or the like, and (m) expresses 0-2. X represents substituent or unsubstituent C1-C7 alkyl group, and (n) expresses 1-4}. Thereby a thermal transfer sheet capable of producing images that are excellent in various fastnesses and are having high density and are especially having excellent light fastness and antioffsetting function with the dye used therefor easily transferred to a material on which the transfer is made even though the thermal energy is given for a very short period of time.

Description

Detailed Description of the Invention [0001] [Industrial Application Field] The present invention relates to a thermal transfer sheet, and more particularly to a thermal transfer sheet that can produce images with excellent color density, sharpness, and various fastnesses, especially light fastness and set-off resistance. The purpose of the present invention is to provide a thermal transfer sheet that can be formed. [0002] Conventionally, various thermal transfer methods have been known. Among them, a sublimable dye is used as a recording agent, and this is supported on a base sheet such as paper to form a thermal transfer sheet. A sublimation transfer method is performed in which the thermal transfer sheet is layered on a transfer material that can be dyed with a dye, such as polyester woven cloth, and thermal energy is applied in a pattern from the back side of the thermal transfer sheet to transfer the sublimable dye to the transfer material. ing. Recently, methods have been proposed for forming various full-color images on paper or plastic films using the above-mentioned sublimation type thermal transfer method. In this case, the thermal head of the printer 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. 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. [Problems to be solved by the invention] However,
The most important problems in the above thermal transfer method include the color density, light fastness, and set-off resistance of the formed image. In other words, in the case of high-speed recording, the application of thermal energy is
An extremely short time, on the order of seconds or less, is required, and therefore, in such a short time, the sublimable dye and the transfer material are not sufficiently heated, making it impossible to form an image with sufficient density. Therefore, in order to cope with such high-speed recording, sublimable dyes with excellent sublimation properties were developed, but dyes with excellent sublimation properties generally have small molecular weights, so they do not dissolve in the transferred material after transfer. In addition, there is a problem of set-off, in which the light resistance is insufficient and the formed image easily fades, and the dye migrates over time, causing the well-formed image to become distorted or unclear, or to contaminate surrounding objects. It is occurring. If a sublimable dye with a relatively large molecular weight is used to avoid such problems, the sublimation speed will be poor in the high-speed recording method described above, so it will not be possible to form an image with a satisfactory density as described above. there were. 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 set-off resistance. It is an object of the present invention to provide a thermal transfer sheet exhibiting properties. [Means for Solving the Problems] The above objects are achieved by the following present invention. That is, the present invention comprises a base sheet and a dye-carrying layer formed on one side of the base sheet, and the dye contained in the dye-carrying layer has the following general formula (I
) is a thermal transfer sheet characterized by being a dye represented by: embedded image (R1 and R2 in the above formula may be the same or different,
Represents a substituted or unsubstituted alkyl group, cycloalkyl group, aralkyl group, aryl group or heterocyclic group, R1 and R2
At least one of them is a group containing a heterocycle or an aromatic ring. R3 represents a substituted or unsubstituted C1 to C7 alkyl group, a halogen atom, or -SOmR4, R4 represents a substituted or unsubstituted lower alkyl group, benzyl group, halogen atom, cyano group, or hydroxy group, and m is 0 ~2. X is a substituted or unsubstituted C1-C7 alkyl group, a hydrogen atom,
represents a C1 to C8 alkoxy group, halogen atom, acylamino group, alkoxycarbonyl group, cyano group, alkoxycarbonylamino group, aminocarbonylamino group, sulfonylamino group, carbamoyl group, or sulfamoyl group, and n represents 1 to 4. [0005] [Operation] By using a dye with a specific structure, the dye used can be easily transferred to the transfer material even when thermal energy is applied for an extremely short time, resulting in high density and excellent properties. A thermal transfer sheet is provided that provides images with fastness, particularly excellent lightfastness and set-off resistance. [Preferred Embodiments] Next, the present invention will be explained in more detail by citing preferred embodiments. The dye of the general formula (I) used in the present invention can be prepared by a known method, for example, the following general formula (
It can be easily produced by diazotizing the thiadiazole compound represented by a) according to a conventional method and coupling it with the aniline derivative represented by the general formula (b). embedded image (In the formula, R1 to R3, X and n are as defined above.) Examples of preferable substituents represented by R1 in the above general formula (I) include a methyl group, Alkyl groups such as ethyl, propyl, butyl, hexyl and octyl groups; alkoxyalkyl groups such as methoxyethyl and ethoxyethyl; hydroxyalkyl groups such as hydroxyethyl and β-hydroxypropyl; chloroethyl, etc. Examples include halogenoalkyl groups such as cyanomethyl groups and cyanoethyl groups; cycloalkyl groups such as cyclopentyl groups and cyclohexyl groups. A preferable group as R2 is represented by -R5-A, and R5 is an alkylene group, an alkyleneoxy group, -O
-, -CO-, -OCOO-, -COO-, -S-, and A is a substituted or unsubstituted phenyl group, naphthyl group, or at least one oxygen atom, nitrogen atom, or sulfur atom. Heterocyclic groups containing, for example, thienyl group,
It represents a pyrrolyl group, a furyl group, an oxazolyl group, a thiazolyl group, an imidazolyl group, an isoxazolyl group, an isothiazolyl group, a pyrazolyl group, an oxadiazole group, a pyridyl group, a pyrimidyl group, and a benzothiazolyl group, and particularly preferred groups are: be. In addition to those exemplified as R1, R3 is preferably a halogen atom or a group represented by -SOm-R4, and R4 is preferably exemplified as R1, with a particularly preferable group being chlorine. Atom, bromine atom, CH3S-, C2H5S-, C4H9S-, C
H3OC2H4S-, C2H5SO-, C2H5SO2
-, H5C2OOCCH2S-, H5C2COOC2H
4S-, HOC2H4S- [Formula 5] and the like. [0010] As X, hydrogen atom; halogen atom such as fluorine, chlorine, bromine, iodine; cyano group; nitro group; alkyl group such as methyl group, ethyl group, propyl group, butyl group;
Alkoxyalkyl groups such as methoxyethyl group and ethoxyethyl group; Hydroxyalkyl groups such as hydroxyethyl group and β-hydroxypropyl group; Halogenoalkyl groups such as chloroethyl group; Cyanoalkyl groups such as cyanomethyl group and cyanoethyl group; cyclopentyl group, Cycloalkyl group such as cyclopentyl group; methoxy group, ethoxy group,
Alkoxy groups such as propoxy groups; Aryl groups such as phenyl, tolyl, halogenophenyl, and alkoxyphenyl groups; Aralkyl groups such as benzyl and phenethyl groups;
Acylamino groups such as acetylamino group and benzoylamino group; Sulfonylamino groups such as methanesulfonylamino group and ethanesulfonylamino group; Methylureido group, 1
, 3-dimethylureido group, ethylureido group, etc.; carbamoyl group, such as methylcarbamoyl group, ethylcarbamoyl group, phenylcarbamoyl group; methylsulfamoyl group, ethylsulfamoyl group, phenylsulfamoyl group, etc. Sulfamoyl group; acetyl group,
Acyl groups such as propanoyl group and benzoyl group; amino groups such as methylamino group, ethylamino group, propylamino group, dimethylamino group and diethylamino group, and the like. [0011] Also, preferred dyes in the present invention have a molecular weight in the range of 300 to 600. Preferred specific examples of dyes of general formula (I) suitable for the present invention are shown in Table 1 below.
Shown below.
Table 1 No. R1
R2 R3
X n molecular weight 1
-C2H5 -CH2Ph
-SC2H5 -NHCOCH3
1 440.62 -C2
H5-CH2Ph-S
C2H5 -NHSO2CH3 1
476.63 -C2H5
-CH2Ph -SC2H5
-CH3 1
397.54 -C2H5 -C
H2Ph-SC2H5
-OC2H5 1 427.6
5 -C6H13 -CH2Ph
-SC2H5 -H
1 439.66
-C2H5 -CH2Ph
-SC2H5 -SO2NH2CH5
1 490.77 -C2
H5-CH2Ph-S
C2H5 -NHCONHC2H5 1
469.68 -C2H4Cl
-CH2Ph -SC2H5
-CH3 1
432.09 -C2H4CN -C
H2Ph-SC2H5
-CH3 1 422.6
10 -C2H4OC2H5 -CH2Ph
-SOC2H5 -CH3
1 441.611
-C2H5 -CH2Ph
-SC2H5 -CH3
1 413.512 -C2
H5-CH2Ph-S
O2C2H5 -CH3 1
429.513 -C2H5
-CH2Ph -Cl
-CH3 1
371.914 -C2H5 -C
H2Ph-Br
-CH3 1 416.3
15 -C2H5 -CH2Ph
-Cl-CH3
2 385.916
-C2H5 -CH2-thienyl
-SC2H5 -CH3
1 402.617 -C2
H5 -CH2-furyl -S
C2H5 -CH3 1
386.518 -C2H5
-CH2-hydrolyl -SC2H5
-CH3 1
385.519 -C2H5 -CH2-
Henso Thiazoryl -SC2H5
-CH3 1 453.6
20 -C2H5 -C2H4Ph
-SC2H5 -CH3
1 410.621
-C2H5 *1
-SC2H5 -NHCOCH3
1 431.522 -C2
H5 -CH2-thienyl -CH
2Ph −H 1
389.623-C2H5
-CH2-thienyl -SC2H5
-NHCOCH3 1
446.624 -C2H5 -CH
2-thienyl -SC2H5
-NHSO2CH3 1 482.7
25 -C2H5 -CH2-furyl -SC2H5 -H
1 402.626
-C2H5 -CH2-furyl
-SC2H5 -CONHCH3
1 430.527 -C2
H5 -CH2-thiasolyl-S
C2H5 -NHCOCH3 1
447.628 -C2H5
-CH2-thiazolyl -SC2H5
-NHSO2CH3 1
483.629 -C2H5 -C
2H4OCOOPh -SC2H5
-NHCOCH3 1 514.6
30 -C2H5 *2
-SC2H5 -H
1 390.531
-C2H5 -CH2-benzothiazolyl -SC2H5 -NHCOCH3
1 497.632 -C2
H5 -CH2-benzothiazolyl-S
C2H5 -OC2H5 1
484.733-C2H5
*3 -SC2H5
-H 1
390.534 -C2H5 *
3-SC2H5
-NHCOCH3 1 447.6
35 -C2H5 -CH2-benzothiazodyryl -Cl -NHCO
CH3 1 472.036
-C2H5 -C2H4COOPh
-SC2H5 -H
1 441.637 -C2H4
COOC2H5 -CH2Ph -
SC2H4OH-H1
471.638 -C2H4COOC
2H5 -CH2Ph -SC2H
5-NHCOCH3 1
512.639 -C2H5 -C
2H4COOPh-SC2H5
-H 1 441
．． 640 -C2H5 -C2H4
OCOPh -SC2H5 -NHC
OCH3 1 498.641
-C2H5 -C2H4OCOPh
-SC2H5 -H
1 441.642 -
C2H5 *4 -
SC2H5-H
1 450.6 ##STR6## The thermal transfer sheet of the present invention is characterized by the use of the above-mentioned specific dye, and other than that, the structure may be the same as that of conventionally known thermal transfer sheets. The base sheet used in the thermal transfer sheet of the present invention containing the above-mentioned dye may be any conventionally known material having a certain degree of heat resistance and strength, for example, 0.5 to 50 μm.
m, preferably about 3 to 10 μm thick paper, various processed papers, polyester film, polystyrene film, polypropylene film, polysulfone film, polycarbonate film, aramid film, polyvinyl alcohol film, cellophane, etc. Particularly preferred is polyester. It's a film. The dye-supporting layer provided on the surface of the base sheet as described above is a layer in which the dye of the general formula (I) is supported by an arbitrary binder resin. As the binder resin for supporting the dye, any conventionally known binder resin can be used, and preferred examples include ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, and butyric acid acetate. Examples include cellulose resins such as cellulose, vinyl resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetoacetal, polyvinylpyrrolidone, and polyacrylamide. Among these, polyvinyl butyral and polyvinyl acetal are particularly heat-resistant. , is preferable from the viewpoint of dye migration. The dye-carrying 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-supporting layer is prepared by adding the dye, binder resin, and other optional components in a suitable solvent, dissolving or dispersing each component, and preparing a coating solution or ink for forming the dye-supporting layer. It is formed by coating and drying on the above base sheet. The support layer formed in this way is
The thickness is about 0.2 to 5.0 μm, preferably about 0.4 to 2.0 μm, and the above-mentioned dye in the support layer accounts for 5 to 70% by weight, preferably 10 to 60% by weight of the weight of the support layer. Preferably, it is present in an amount of %. The thermal transfer sheet of the present invention as described above is sufficiently useful for thermal transfer as it is, but an anti-adhesion layer, that is, a release layer may be further provided on the surface of the dye-carrying layer.
By providing such a layer, it is possible to prevent adhesion between the thermal transfer sheet and the transfer material during thermal transfer, use a higher thermal transfer temperature, and form an image with even better density. [0016] As this mold release layer, even if an inorganic powder with anti-adhesive property is simply attached, it shows a considerable effect, and furthermore,
For example, from resins with excellent mold release properties such as silicone polymers, acrylic polymers, and fluorinated polymers,
It can be formed by providing a release layer of 5 μm, preferably 0.05 to 2 μm. Incidentally, the above-mentioned inorganic powder or mold-releasing polymer exhibits a sufficient effect even when included in the dye-carrying layer. Furthermore, a heat-resistant layer may be provided on the back surface of such a thermal transfer sheet in order to prevent the adverse effects of the heat of the thermal head. [0017] The transfer material used to form an image using the thermal transfer sheet as described above may be any material as long as its recording surface has dye receptivity for the above-mentioned dyes. In the case of paper, metal, glass, synthetic resin, etc., which do not have dye receptivity, a dye receptive layer may be formed on at least one surface thereof. Any conventionally known means for applying thermal energy can be used to apply thermal energy when performing thermal transfer using the thermal transfer sheet of the present invention as described above and the recording material as described above, such as a thermal printer (e.g. By controlling the recording time using a recording device such as Video Printer VY-100 (manufactured by Hitachi, Ltd.), the intended purpose can be fully achieved by applying thermal energy of about 5 to 100 mJ/mm2. I can do it. In particular, the thermal transfer sheet of the present invention can form a magenta image, and when used in combination with yellow and cyan thermal transfer sheets, can provide a full-color image with excellent color reproducibility. [Example] Next, the present invention will be explained in more detail by referring to reference examples, working examples, and comparative examples. In the text, parts or percentages are based on weight unless otherwise specified. EXAMPLE An ink composition for forming a dye-carrying layer having the following composition was prepared and coated on a 6 μm thick polyethylene terephthalate film whose back surface had been heat-resistant treated so that the dry coating amount was 1.0 g/m2. After drying, a thermal transfer sheet of the present invention was obtained. However, when the dye was insoluble in the above composition, DMF, dioxane, chloroform, etc. were appropriately used as a solvent. In addition, when sufficient dissolution was not achieved even when using the above-mentioned solvent, the filtrate was used. Next, a synthetic paper (manufactured by Oji Yuka Co., Ltd., Yupo FPG #150) was used as a base sheet, and a coating liquid having the following composition was applied to one side of the paper at a rate of 10.0 g/m2 when dry. It was coated and dried at 100° C. for 30 minutes to obtain a transfer material. Polyester resin (Vylon200, manufactured by Toyobo)
11.5 parts vinyl chloride
Vinyl acetate copolymer (VYHH, manufactured by UCC)
5.0 parts Amino modified silicone (KF-39
3, Shin-Etsu Chemical Co., Ltd.) 1.2 parts Epoxy modified silicone (X-22-343, Shin-Etsu Chemical Co., Ltd.) 1.2 parts Methyl ethyl ketone/Toluene/
Cyclohexanone (weight ratio 4:4:2)


102.0 parts [0022] The thermal transfer sheet of the present invention and the transfer material described above were placed one on top of the other with their respective dye-carrying layers and dye-receiving surfaces facing each other, and a head applied voltage of 10 V was applied from the back side of the thermal transfer sheet. Printing time 4.0msec. Recording was performed with a thermal head under the following conditions, and the results shown in Table 2 below were obtained. [0023]
Table 2
Dye Hue Color density Lightfastness Set-off 1 Red 2.36
○ ◎2 Red
2.05 ○ ◎3
Red 2.43 ○
○4 Red 2.21
○ ◎5 Red 2
．． 31 ○ ◎6
Red 2.06 ○
◎7 Red 2.27 ○
◎8 Red 2.23
○ ◎9 Red
2.42 ○ ◎10
Red 2.28 ○
◎11 Red 2.36
○ ◎
12 red 2.24
○ ◎13 Red 2.
56 ○ ○14
Red 2.45 ○
◎15 Red 2.32 ○
○16 Red 2.4
7 ○ ◎17
Red 2.54 ○ ○
18 Red 2.37 ○
○19 Red 2.13
○ ◎20 Red 2.43 ○ ◎2
1 Red 2.35 ○
◎22 Red 2.51
○ ○23 Red
2.28 ○ ◎24
Red 2.12 ○
◎25 Red 2.45
○ ○26 Red
2.40 ○ ◎27
Red 2.43 ○
◎28 Red 2.20
○ ◎29 Red
2.15 ○ ◎30
Red 2.47 ○
◎31 Red 2.23
○ ○32 Red
2.07 ○ ◎33
Red 2.44 ○
○34 Red 2.53
○ ◎35 Red 2
．． 57 ○ ◎36
Red 2.40 ○
◎37 Red 2.11
○ ◎38 Red 2.
02 ○ ◎39
Red 2.37 ○
◎40 Red 2.48 ○
◎ 41
Red 2.37 ○
◎42 Red 2.35
○ ◎ [0024] Comparative example 1~
3 The dyes shown in Table 3 were used in place of the dyes in Example 1, and the other conditions were the same as in Example 1 to obtain the results shown in Table 3.
Table 3 Dye Hue Molecular weight Coloring density Light resistance Set-off A Red 321.5 2.27 △
△ B Red 339.5
2.13 △ △ C Red
348.4 1.12 ×
△ Dye A; [Chemical 7] Dye B; [Chemical 8] Dye C; [Chemical 9] The color density in the above was measured with a densitometer RD-918 manufactured by Macbeth, USA. It is a value. Light resistance is determined by using xenon as a light source and irradiating the grade 3 blue scale piece until it changes color, then ◎ indicates that no discoloration is observed at all, ○ indicates that slight discoloration is observed, and △ indicates that discoloration is clearly observed. And so. Set-off resistance is defined as the sharpness of the image does not change after the recorded image is left in an atmosphere at 70°C for 48 hours, and the white paper does not become colored even when the surface is rubbed with white paper. An image in which sharpness was lost and the white paper was slightly colored was rated as ◯, an image in which sharpness was lost and the white paper was colored was rated as △, and an image became unclear and the white paper was markedly colored in was rated as ×. [0027] According to the present invention as described above, by using a dye with a specific structure, the dye used can easily be transferred to a transfer material even when thermal energy is applied for an extremely short time. A thermal transfer sheet is provided which provides images with high density and excellent fastness properties, particularly excellent light fastness and set-off resistance.

Claims (2)

[Claims] Claim 1: Consists of a base sheet and a dye-carrying layer formed on one side of the base sheet, wherein the dye contained in the dye-carrying layer is a dye represented by the following general formula (I). A thermal transfer sheet characterized by: embedded image (R1 and R2 in the above formula may be the same or different,
Represents a substituted or unsubstituted alkyl group, cycloalkyl group, aralkyl group, aryl group or heterocyclic group, R1 and R2
At least one of them is a group containing a heterocycle or an aromatic ring. R3 represents a substituted or unsubstituted C1 to C7 alkyl group, a halogen atom, or -SOmR4, R4 represents a substituted or unsubstituted lower alkyl group, benzyl group, halogen atom, cyano group, or hydroxy group, and m is 0 ~2. X is a substituted or unsubstituted C1-C7 alkyl group, a hydrogen atom,
represents a C1 to C8 alkoxy group, halogen atom, acylamino group, alkoxycarbonyl group, cyano group, alkoxycarbonylamino group, aminocarbonylamino group, sulfonylamino group, carbamoyl group, or sulfamoyl group, and n represents 1 to 4. ) 2. The thermal transfer sheet according to claim 1, wherein the molecular weight of the dye is in the range of 300 to 600.