JP3263138B2 - Thermal transfer sheet - Google Patents

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 method for forming a color image having high gradation.
The present invention relates to a sublimation-type thermal transfer sheet capable of forming a high-quality transfer image with uniform and excellent dye transferability of not only a shadow portion but also a highlight portion.

[0002]

2. Description of the Related Art Conventionally, various thermal transfer methods are known. Among them, a sublimable dye is used as a recording agent, and this is carried on a base sheet such as a polyester film to form a thermal transfer sheet. Dyeable transfer material, for example,
There have been proposed methods of forming various full-color images on a transfer material having a dye receiving layer formed on paper, plastic film, or the like. In this case, a thermal head of a printer is used as a heating means, and a large number of three or four color dots are transferred to a transfer material by heating for a very short time, and a full-color image of an original is formed by the multicolor dots. Is to reproduce. The image formed in this way is very clear because the coloring material used is a dye, and is excellent in transparency, so that the obtained image is excellent in the reproducibility and gradation of intermediate colors. It is possible to form a high-quality image which is similar to an image by offset printing or gravure printing, and is comparable to a full-color photographic image.

[0003]

In order to form a high-quality image comparable to a photograph by the above-described thermal transfer method,
The configuration of the thermal transfer sheet to be used is important. First, it is necessary that the dye in the dye layer be present uniformly. This can be achieved by using a resin having a high affinity for the dye as a binder for the dye layer, but in this case, the transferability of the dye to the transfer material is not sufficient, and a high density image is not formed. There is a problem. On the other hand, if a resin having low affinity for the dye is used as the binder resin, the transferability of the dye to the material to be transferred is good, but the dye aggregates or crystallizes in the dye layer during storage of the thermal transfer sheet. Or bleed out to the surface of the dye layer, making it difficult to transfer the dye uniformly to the material to be transferred. This problem appears as significant transfer unevenness (color unevenness) in a highlight portion (light color portion) when a color image is formed. Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to form a color image with gradation,
It is an object of the present invention to provide a thermal transfer sheet that enables uniform and excellent dye transfer not only in a shadow portion but also in a highlight portion and does not cause uneven transfer.

[0004]

The above object is achieved by the present invention described below. That is, the present invention is a thermal transfer sheet in which a dye layer containing a dye which is transferred by heating and transferred onto a transfer material is laminated on a base sheet, wherein the binder component of the dye layer is a thermal transfer sheet which is a mixture of one of the following components (I) and (II). (I) 5% by weight of the acetalized portion in the total amount of the polymer
A polyvinyl acetoacetal resin having 0% by weight or more and 80% or more of an acetalized portion is acetoacetal. (II) 5% by weight of the acetalized portion in the total amount of the polymer
A polyvinyl acetal resin in which 0% by weight or more and 40% or more of an acetalized portion is acetalized with an aldehyde having a phenyl group. The present invention also provides a base sheet
Dye which is transferred to the material to be transferred by heating
Is a thermal transfer sheet having a dye layer containing
Wherein the binder component of the dye layer is the following component (III):
It is a thermal transfer sheet characterized by the following. (III) The weight% of the acetalized portion is in the total amount of the polymer
50% by weight or more and 10% or more of the acetalized portion
The top is acetalized with an aldehyde having a phenyl group
Polyvinyl acetal resin.

[0005]

By adopting a specific binder resin as the binder resin constituting the dye layer, the dye has good releasability despite the good compatibility between the dye and the binder resin. In the case of forming a reliable color image, it is possible to provide a thermal transfer sheet that enables uniform and good dye transfer not only in a shadow area but also in a highlight area and does not cause uneven transfer.

[0006]

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail hereinafter with reference to preferred embodiments illustrated in the drawings. As shown in FIG. 1, a thermal transfer sheet 1 according to the present invention
A dye layer 3 is provided thereon. Examples of the base sheet 2 include a condenser paper, a polyester film, a polystyrene film, a polysulfone film, a polyimide film, a polyvinyl alcohol film, an aramid film such as cellophane, a polyetherimide film,
Paper or a film such as a polyetheretherketone film or a polypalvanic acid film is used, and its thickness is 1.5 to 50 μm, preferably 2 to 9 μm.
When these papers or films require heat resistance in the price and unprocessed state, condenser paper is used.On the other hand, it has mechanical strength and is used for handling when creating a thermal transfer sheet or in a thermal printer. Polyester film is preferably used when it is important not to break when running and to have a smooth surface.

The dye layer 3 mainly comprises a dye and a specific binder resin. The dye is a dye that is transferred by melting, diffusing, or sublimating by heat, and a disperse dye is particularly preferably used. These dyes have a molecular weight of about 150 to 550, and are selected in consideration of sublimation (melting) temperature, hue, light resistance, ink formation, solubility in a binder resin, and the like. , ヂ arylmethane, triarylmethane, thiazole, methine,
Azomethine-based, xanthine-based, oxazine-based, thiazine-based, azine-based, acridine-based, azo-based, spirodipyran-based, indolinospiropyran-based, fluoran-based, rhodamine-lactam-based, and anthraquinone-based dyes are typical, and specifically, The following dyes can be preferably used. CI (Color Index) yellow 51, 3, 54, 7
9, 60, 23, 7, 141; CI Disperse Blue 24, 56, 14, 301, 334, 165, 19, 7
2, 87, 287, 154, 26; CI disperse threads 135, 146, 59, 1, 73, 60, 167;
CI Disperse Violet 4, 13, 26, 36,
56, 31; CI Solvent Violet 13, CI Solvent Black 3, CI Solvent Green 3, CI
Solvent Yellow 56, 14, 16, 29; CI Solvent Blue 70, 35, 63, 36, 50, 49, acetalized portion, 105, 97, 11; CI Solvent Red 135, 81, 18, 25, 19, 23, 24,
143, 146, 182, etc.

More specifically, for example, 3,3'-diethyloxathiocyanine iodide astrazone pink FG (manufactured by Bayer, CI48015), 2,2 '.
Carbocyanin (CI808), Astraphyloxin F
F (CI48070), Astrazon Yellow 7 GLL
Methine (cyanine) basic dyes such as monomethine, dimethine or trimethine, such as (CI Basic Yellow 21), Aizen Kachiron Yellow 3GLH (manufactured by Hodogaya Chemical, CI48055), Aizen Kachiron Red 6BH (CI48020); Diphenylmethane-based basic dyes such as auramine (CI655); malachite green (CI42000), brilliant green (CI4)
2040), magenta (CI42510), metal violet (CI42535), crystal violet (CI4
2555), Methyl Green (CI684), Victoria
Triphenylmethane-based basic dyes such as Blue B (CI44045); pyronin G (CI739), rhodamine B (CI4
5170), xanthene-based basic dyes such as rhodamine 6G (CI45160); acridine yellow G (CI785);
Leonin AL (CI46075), benzoflavin (CI79
1), acridine-based basic dyes such as Affine (CI46045); quinone-imine-based basic dyes such as Neutral Red (CI50040), Astrazone Blue BGE / x 125% (CI51005), Methylene Blue (CI52015); And basic dyes such as anthraquinone-based basic dyes having a quaternary ammonium group. These dyes can be used as they are or in a form obtained by treating these dyes with alkali, and a counter ion exchanger or a leuco form of these dyes can also be used. When a colorless or light-colored leuco dye or the like is used in a normal state, a developer may be included in the material to be transferred.

Further preferred dyes are exemplified.

Embedded image (R ₁ in the above general formula is a substituted or unsubstituted alkyl group or alkoxy group, and R ₂ is an alkoxycarbonyl group, an alkylaminocarbonyl group, an alkoxy group, an alkoxyalkoxy group, an alkyl group, a cycloalkyl group or a heteroalkyl group. A ring group, R ₃ and R ₄ are substituted or unsubstituted alkyl groups, R ₅ is a substituted or unsubstituted aryl group or a substituted or unsubstituted aromatic heterocyclic group, R ₆ is a substituted or unsubstituted An alkyl group, R ₁₁ and R ₁₂ represent a substituted or unsubstituted alkyl group, an aryl group, a cycloalkyl group or a vinyl group,
R ₉ is CONHR, NHCOR, SO ₂ NHR, NHSO
₂ R (R represents a substituted or unsubstituted alkyl group, cycloalkyl group, aryl group or aromatic heterocyclic group), R
₁₀ represents a substituted or unsubstituted alkyl group, alkoxy group, alkylcarbonylamino group, alkylsulfonylamino group, carbamoyl group, sulfamoyl group, hydrogen atom or halogen atom. )

[0010] The binder resin used in the present invention mainly polyvinyl acetal resins or Ranaru. The polyvinyl acetal resin used as a binder resin in the present invention is
In the present invention, the following three resins (I) and (II)
Mixture (good or correct mixing ratio in this case the (weight), prior to
In the range of about 5 to 50 parts by weight per 100 parts by weight of the
Yes) or (III) is used . (I) weight percent of A acetal moiety is in the polymer total amount 5
A polyvinyl acetoacetal resin in which 0% by weight or more and 80% or more of the acetalized portion is acetoacetal; (II) 5% by weight of the acetalized portion is 5% in the total amount of the polymer;
A mixture with a polyvinyl acetal resin in which 0% by weight or more and 40% or more of an acetalized portion is acetalized with an aldehyde having a phenyl group . ( III ) A polyvinyl acetal resin in which the weight% of the acetalized portion is 50% by weight or more in the total amount of the polymer and at least 10% of the acetalized portion is acetalized with an aldehyde having a phenyl group.

In the above, the acetalized portion and its type can be easily adjusted to the above range and type by adjusting the type and reaction amount of the aldehyde used in acetalizing polyvinyl alcohol. In the above (I) , the weight% of the acetalized portion
Is less than 80% by weight in the total amount of the polymer and / or 80% or more of the acetalized portion is not acetoacetal, the uniform transferability in the highlight portion, ie, the color of the highlight portion, is the object of the present invention. The reproducibility becomes insufficient. Similarly, in the above examples (II) and (III) ,
If the predetermined conditions are not satisfied, the uniform transferability in the highlighted portion, that is, the color reproducibility of the highlighted portion, which is also the object of the present invention, becomes insufficient. The molecular weight of the polyvinyl acetal resin is not particularly limited.
Preferably it is in the range of 10,000.

In the present invention, in addition to the polyvinyl acetal resin, other known binder resins, for example, pol ester resin, ethylene / vinyl acetate copolymer, polycarbonate, cellulose derivative, acrylic resin, and other polyvinyl acetal resins Resins and the like can be used in combination as long as they are used to some extent. Further, in the present invention, in order to improve the heat resistance of the dye layer, at least two functional groups which react with a hydroxyl group are provided as long as the object of the present invention is not hindered.
A crosslinker having at least one polyisocyanate, such as a polyisocyanate compound, may be used when forming the dye layer.

The ratio of the dye contained in the dye layer depends on the sublimation (melting) temperature of the dye and the level of covering power (color rendering) in a color-developed state. (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, image quality such as print density and thermal sensitivity is not preferable, while 3.0
If it exceeds 300, the adhesiveness to the film and the storability tend to decrease. In order to provide the dye layer 3 on the base sheet 2, the dye layer ink is dissolved with a dye, a binder resin and an appropriate solvent to form an ink for the dye layer, which is applied on the base sheet 2 by an appropriate printing method or coating method. And dry.
It is preferable that the dye is substantially dissolved in the binder resin. Incidentally, an optional additive may be added to the dye layer ink as required.

Although the basic structure of the thermal transfer sheet of the present invention is as described above, FIG. 2 shows a case where the surface of the base sheet is directly heated by a contact type heating means such as a thermal head. As described above, by providing the slip layer 4 containing a lubricant such as wax or a release agent on the side of the base sheet 2 where the dye layer 3 is not provided, the heating means such as a thermal head can be connected to the base sheet. It is possible to prevent fusion and improve the slipperiness. The thermal transfer sheet of the present invention may be a sheet-like sheet cut to a required size, may be a continuous form or a rolled-up form, or may be a tape form having a smaller width.

When the dye layer 3 is provided on the base sheet 2, a dye layer ink containing the same dye may be applied to the entire surface of the base sheet 2. A plurality of dye layer inks each containing a dye may be formed in different areas of the surface of the base sheet 2 respectively. For example, as shown in FIG. 3, a thermal transfer sheet in which a black dye layer 5 and a red dye layer 6 are laminated in parallel on the base sheet 2, or a yellow dye layer 7, as shown in FIG. It may be a thermal transfer sheet in which a red dye layer 8, a blue dye layer 9, and a black dye layer 10 are repeatedly provided on the base 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. By providing perforations on the thermal transfer sheet or providing detection marks for detecting the positions of areas having different hues, convenience in use can be achieved. 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 material sheet 12 of the material to be transferred are combined with the thermal transfer sheet of the present invention and an arbitrary material to be transferred. And dye layer 3
By applying heat energy according to the image information to the interface between the dye receiving layer 13 and the heat receiving means such as a thermal head 14, the dye in the dye layer 3 is transferred to the dye receiving layer 13 and the desired image is formed. It can be formed in the receiving layer 13.

As a heat source for giving thermal energy, laser light, infrared flash,
A known device such as a hot pen can be used. The thermal energy may be applied from the thermal transfer sheet side, from the transfer material side, or from both sides. From the viewpoint of effective use of thermal energy, thermal energy is preferably applied from the thermal transfer sheet side. . However, when the thermal energy is applied from the transfer material side, the applied thermal energy is controlled to express the gradation of the image, or the dye is promoted to diffuse on the material to be transferred so that the continuous image is formed. This is preferable in terms of more reliably expressing the gradation, and the method of applying thermal energy from both sides can simultaneously enjoy the advantages of both methods. When the thermal head 14 is used as a heat source for applying thermal energy, the applied thermal 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 applying heat energy, the applied heat energy can be changed by changing the amount of laser light or the irradiation area. If a dot generator having an acousto-optic element is used, heat energy corresponding to the size of a halftone dot can be applied. When using laser light, it is recommended that the thermal transfer sheet and the material to be transferred be sufficiently adhered to each other, and that the surface to be irradiated with laser light be colored black, for example, in order to improve the absorption of laser light. It is good to keep. Alternatively, if a non-sublimable substance that absorbs laser light and converts it into heat is added to the dye layer 3, heat is more efficiently transferred to the dye and the resolution of the image is increased.

When an infrared flash lamp is used as a heat source for applying thermal energy, it may be performed in the same manner as when a laser beam is used, or a pattern such as black, which continuously expresses the density of an image, or a halftone dot pattern. Or a combination of a color layer such as black on one surface and a negative pattern corresponding to the negative of the above pattern. When thermal 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 and received by the dye-receiving layer 13 in an amount corresponding to the applied thermal energy to form an image. Form as desired.

By the thermal transfer recording as described above, the dye corresponding to the thermal energy is thermally transferred to the dye receiving layer, so that a one-color image can be recorded. By sequentially replacing the red, blue and, if necessary, black thermal transfer sheets and performing thermal transfer in accordance with each color, a photographic color image composed of a combination of each color can also be obtained. Instead of using the thermal transfer sheet of each color as described above, a thermal transfer sheet having an area formed by separately applying each color as shown in FIG. 4 is used. First, a yellow color separation image is thermally transferred using the yellow area. Then, a thermal transfer is performed using the red area of the thermal transfer sheet, and thereafter, a method of thermally transferring a yellow, red, indigo, and, if necessary, a black color separation image by repeating the thermal transfer sequentially, There is an advantage that the replacement of the battery becomes 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 adhesiveness between the heat transfer sheet and the material to be transferred, and the heat energy.

The thermal transfer sheet of the present invention is used in combination with a material to be transferred, so that it can be used for printing using various thermal printing printers, facsimile or magnetic recording, and printing from a television screen. It can be used for making. 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, if necessary, black, and is stored. When a signal of each color separation pattern is output, and thermal energy corresponding to the signal is applied to the superimposed body of the thermal transfer sheet and the transfer target material by the above-described heat source such as a thermal head, and thermal transfer is sequentially performed for each color, A television screen can be reproduced as a sheet-like hard print. When a combination of the transfer material and the thermal transfer sheet of the present invention is used for printing out such a television screen, the transfer material is usually a white dye-receiving layer alone or a colorless and transparent dye-receiving layer. It is convenient to obtain a reflection image by using a base material sheet such as paper or a base material sheet such as paper with a white dye receiving layer.

The same operations as described above can be performed when a combination of characters, figures, symbols, colors, and the like formed on a CRT screen by operating a computer, and a graphic pattern are used as an original image. When the original image is a fixed image such as a painting, photograph, or printed matter, or an actual object such as a person, still life, or landscape, an image is formed in the same manner as described above by using an appropriate means such as a video camera. You can do it. Further, in producing signals of each color separation pattern from the original image, an electronic plate making machine (color scanner) used for photomechanical printing may be used.

[0023]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In the description, parts and% are based on weight unless otherwise specified. < Examples 1 to 6 and Comparative Examples 1 to 4 > An ink for a dye layer having the following composition was prepared, and a 6 μm-thick polyethylene terephthalate film having a heat-resistant treatment on the back surface was dried at a coating weight of 1.0 g / m ² . The resultant was coated and dried to obtain thermal transfer sheets of the present invention and comparative examples shown in Tables 3 and 4. ( Ink composition ) Dye of the following structural formula a part Polyvinyl acetoacetal resin b part of Table 1 below Polyvinyl acetal resin b part of Table 2 methyl ethyl ketone (100-abc) / 2 parts toluene (100-ab) -C) / 2 parts However, in the above composition, when the dye is insoluble in the solvent,
DMF, dioxane, chloroflume or the like was appropriately used as a solvent.

Next, a synthetic paper (Yupo FPG # 150, manufactured by Oji Oil Chemical Co., Ltd.) was used as a base sheet, and a coating solution having the following composition was dried on one surface thereof at a rate of 10.0 g / m ² when dried. And dried at 100 ° C. for 30 minutes to form a dye receiving layer to obtain a transfer material. 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 above-mentioned material to be transferred are overlapped with their respective dye layers and dye receiving surfaces facing each other. Time 1
0 msec. Recording was performed with a thermal head under the following conditions, and the results shown in Tables 3 and 4 below were obtained.

Embedded image

[0026]

[Table 1]

[Table 2]

[0027]

[Table 3]

[Table 4]

[0028]

According to the present invention as described above, by adopting a specific binder resin as the binder resin constituting the dye layer, the dye can be released even though the compatibility between the dye and the binder resin is good. In order to form a color image with gradation, a thermal transfer sheet capable of uniform and excellent dye transfer not only in a shadow portion but also in a highlight portion and without causing transfer unevenness is provided. Can be done.

[Brief description of the drawings]

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

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

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

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Thermal transfer sheet 2 ... Base sheet 3 ... Thermal transfer layer 11 ... Heat transfer sheet 12 ... Base sheet 13 ... Reception layer 14 ... Thermal head 15 ... Platen roll

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-151484 (JP, A) JP-A-4-22685 (JP, A) JP-A-4-236205 (JP, A) JP-A-4- 148990 (JP, A) JP-A-5-85070 (JP, A) JP-A-3-65391 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/38-5 / 40

Claims (2)

(57) [Claims] 1. A thermal transfer sheet comprising a dye sheet containing a dye which is transferred by heating and transferred onto a material to be transferred, on a base sheet, wherein the binder component of the dye layer is as follows: A thermal transfer sheet comprising a mixture of the components (I) and (II). (I) 5% by weight of the acetalized portion in the total amount of the polymer
A polyvinyl acetoacetal resin having 0% by weight or more and 80% or more of an acetalized portion is acetoacetal . (II) 5% by weight of the acetalized portion in the total amount of the polymer
A polyvinyl acetal resin in which 0% by weight or more and 40% or more of an acetalized portion is acetalized with an aldehyde having a phenyl group. (2) Transfer to the base sheet by heating
A dye layer containing a dye to be transferred onto a transfer material is laminated.
A thermal transfer sheet comprising the binder of the dye layer
Wherein the component is the following component (III):
Photo sheet. (III) The weight% of the acetalized portion is in the total amount of the polymer
50% by weight or more and 10% or more of the acetalized portion
The top is acetalized with an aldehyde having a phenyl group
Polyvinyl acetal resin.