JP2681781B2 - Thermal transfer sheet - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a thermal transfer sheet, and more particularly, to providing a thermal transfer sheet which can easily give a recording material having excellent robustness to a material to be transferred. With the goal. (Prior 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 paper to form a thermal transfer sheet, which is then dyed with a sublimable dye. A sublimation transfer method has been performed in which a sublimable dye is transferred to a transfer-receiving material by applying thermal energy in a pattern form from the back surface of a thermal transfer sheet to a transferable material such as a polyester woven cloth. (Problems to be Solved by the Invention) In the above-described sublimation transfer method, in the sublimation printing method in which the material to be transferred is, for example, a woven fabric made of polyester or the like, the heat energy is applied for a relatively long time. As a result, relatively good dye transfer is achieved as a result of heating with the applied thermal energy. However, due to advances in recording methods, using a thermal head or the like at a high speed, for example, a polyester sheet or a transfer material provided with a dye receiving layer on paper, and using delicate characters or When a graphic or photographic image is formed, the application of thermal energy is required to be performed in a very short time of less than a second, and therefore, in such a short time, the sublimable dye and the transfer material are not sufficiently heated. Therefore, an image having a sufficient density cannot be formed. Therefore, to cope with such high-speed recording, sublimable dyes having excellent sublimability have been developed. In this case, there is a problem that the dye migrates with time or bleeds on the surface, so that the formed image is disturbed, becomes unclear, or contaminates surrounding articles. In order to avoid such a problem, when a sublimable dye having a relatively large molecular weight is used, the sublimation speed is inferior in the high-speed recording method as described above, so that an image having a satisfactory density cannot be formed as described above. Met. Therefore, in the thermal transfer method using a sublimable dye, by applying thermal energy for an extremely short time as described above, a clear image having a sufficient density is provided, and the formed image exhibits excellent various fastnesses. At present, there is a strong demand for the development of thermal transfer sheets. The present inventor has conducted intensive studies to respond to the strong demands of the industry as described above, and as a result of the conventional sublimation printing method for polyester woven fabric and the like, the surface of the woven fabric is not smooth. It is essential that the dye used does not adhere sufficiently to a certain woven fabric, and that the dye used is sublimable or vaporizable (that is, a property capable of transferring the space existing between the thermal transfer sheet and the woven fabric). However, when a transfer target material is a polyester sheet or surface-treated paper having a smooth surface, the thermal transfer sheet and the transfer target material are sufficiently adhered to each other at the time of thermal transfer, so that only the dye sublimation and vaporization properties are obtained. However, it is not an absolutely necessary condition, and it is also very important that the dye can be transferred by heat at the interface between the two in contact with each other. By By selecting a dye having an appropriate molecular structure, it is possible to obtain a good heat even for a dye having a high molecular weight which is considered to be unusable by conventional common sense. It has been found that it has a migration property. By using a thermal transfer sheet carrying such a dye, the dye used can be easily transferred to the material to be transferred, even if heat energy is applied for an extremely short time, and high density and excellent various fastnesses can be obtained. The present invention was completed on the knowledge that a recorded image having the image was formed. (Means for Solving the Problems) That is, the present invention comprises a substrate sheet and a dye carrying layer formed on one surface of the substrate sheet, and the dye contained in the dye carrying layer is as follows: A thermal transfer sheet characterized by being a dye represented by the general formula (I). However, R ₁ in the above formula is CONHR, CONRR ′, NHCOR, SO ₂ NH
R, NHSO ₂ R (R and R ′ represent an alkyl group in which a hydrogen atom may be substituted with a fluorine atom, a cycloalkyl group or an aryl group which may have a substituent), R ₂ and
R ₃ represents a halogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, an acylamino group, an aminocarbonyl group, an alkylaryl group or an aryl group, and R ₄ and R ₅ represent an alkyl group which may have a substituent or an aralkyl. Represents a group, an aryl group or a hydrogen atom, A is nothing (in this case, R ₁
A ring with Alternatively, the atomic group constituting the naphthalene ring which may have a substituent as described above (in this case, the ring having R ₁ is (R ₆ represents a hydrogen atom or a substituent as described above). (Function) The present inventor continued various detailed studies on adaptability of various dyes as a dye for a thermal transfer sheet, and as a result,
Only the dye represented by the general formula (I) has an excellent heat transfer property even when its molecular weight is relatively large, and further exhibits excellent dyeing property and color forming property on a transfer material, Moreover, the transferability (bleeding property) of the dye in the transferred material to be transferred is not observed, and it has been found that it has an extremely ideal property as a dye for a thermal transfer sheet. (Preferred Embodiment) Next, the present invention will be described in more detail. The dye represented by the general formula (I), which is the main feature of the present invention, is a conventionally known dye containing a p-phenylenediamine compound and a phenol or naphthol. It is obtained by the coupling method of. The dye of the general formula (I) preferred in the present invention is
When A is nothing, NHCOR where R ₁ is present at the position of 1 (R
(As defined above) When the dye and A, which are groups, together form a naphthalene ring, CONH in which R ₁ is in the 1 position
Dyes which are R or CONRR ′ (R and R ′ are as defined above) groups, particularly preferred in the above preferred dyes, where R ₄ and / or R ₅ are C _{2 to} C ₁₀ alkyl groups. ,
And at least one of R ₄ and R ₅ has a polar group such as a hydroxyl group or a substituted hydroxyl group, an amino group or a substituted amino group, and a cyano group is the best result, that is, excellent heat transferability, the material to be transferred. It has excellent dyeing property, heat resistance during transfer, color developability and excellent transfer resistance after transfer. Hereinafter, specific examples of dyes suitable for the present invention are shown below. Table 1 below shows the substituents R _{1 to} R ₅ in the general formula (I). The thermal transfer sheet of the present invention is characterized by using the above-mentioned specific dye as described above, and the other configuration may be the same as the configuration of a conventionally known thermal transfer sheet. The base sheet used in the construction of the thermal transfer sheet of the present invention containing the above dye may be any one as long as it has conventionally known heat resistance and strength to some extent, for example, 0.5 to 50 μm, preferably Paper having a thickness of about 3 to 10 μm, various processed papers, polyester film, polystyrene film, polypropylene film, polysulfone film, polycarbonate film, aramid film, polyvinyl alcohol film, cellophane, etc., and particularly preferred is polyester film. The dye-carrying layer provided on the surface of the base sheet as described above,
This 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 above-mentioned dye, any conventionally known binder resin can be used, and preferred examples include ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxycellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, butyric acid acetylate. Cellulose-based resins such as cellulose, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone, polyvinyl-based resins such as polyacrylamide, and the like, among them, polyvinyl butyral and polyvinyl acetal, heat resistance, This is preferable from the viewpoint of dye transferability and the like. The dye-carrying layer of the thermal transfer sheet of the present invention is basically formed of the above-mentioned materials, but may also contain various additives as conventionally known, if necessary. Such a dye-carrying layer is preferably prepared by adding the above-mentioned dye, binder resin and other optional components in an appropriate solvent and dissolving or dispersing each component to prepare a coating solution or ink for forming a supporting layer. It is formed by coating and drying on the above substrate sheet. The supporting layer thus formed has a thickness of about 0.2 to 5.0 μm, preferably about 0.4 to 2.0 μm, and the dye in the supporting layer is 5 to 70% by weight, preferably 5 to 70% by weight of the supporting layer. It is preferably present in an amount of 10 to 60% by weight. The thermal transfer sheet of the present invention as described above is sufficiently useful as it is for thermal transfer, but an anti-adhesion layer, that is, a release layer may be further provided on the surface of the dye-carrying layer, and such a layer should be provided. Thereby, the adhesion between the thermal transfer sheet and the transfer material during thermal transfer can be prevented, and a higher thermal transfer temperature can be used to form an image with a more excellent density. As this release layer, even if only an anti-adhesive inorganic powder is simply attached, a considerable effect is exhibited.Moreover, for example, a silicone polymer, an acrylic polymer, a resin having excellent release properties such as a fluorinated polymer is 0.01% or less. To 5 μm, preferably 0.05 to 2 μm. The inorganic powder or the releasable polymer as described above has sufficient effects even if it is included in the dye-carrying layer. Further, a heat-resistant layer may be provided on the back surface of such a thermal transfer sheet in order to prevent adverse effects due to heat of the thermal head. 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 a dye receptivity to the above-mentioned dye. In the case of paper, metal, glass, synthetic resin or the like having no dye, a dye receiving layer may be formed on at least one surface thereof. As a transfer material that does not need to form a dye receiving layer,
For example, polyolefin resin such as polypropylene, polyvinyl chloride, halogenated polymer such as polyvinylidene chloride, polyvinyl acetate, vinyl polymer such as polyacrylic ester, polyethylene terephthalate, polyester resin such as polybutylene terephthalate, polystyrene resin, Polyamide resins, copolymer resins of olefins such as ethylene and propylene and other vinyl monomers, ionomers, cellulose resins such as cellulose diacetate, fibers made of polycarbonate, woven cloth,
Films, sheets, molded products and the like can be mentioned. Particularly preferred is a sheet or film made of polyester or a processed paper provided with a polyester layer.
Further, even for paper, metal, glass and other non-dyeing transfer receiving materials, a solution or dispersion of the above-described dyeing resin is applied to the recording surface and dried, or the resin is used. The material to be transferred can be obtained by laminating the film. Further, even in the case of the transfer material having dyeing properties, a dye-receiving layer may be formed on the surface thereof from a resin having better dyeing properties as in the case of the paper. The dye-receptive layer thus formed may be formed of a single material or a plurality of materials, and may further contain various additives within a range not impairing the intended purpose. Of course. Such a dye-receiving layer may be of any thickness, but is generally between 5 and 50 μm. Further, such a dye receiving layer is preferably a continuous coating, but it may be formed as a discontinuous coating by using a resin emulsion or resin dispersion. Such a material to be transferred is basically as described above and can be used satisfactorily as it is. However, it is possible to include an inorganic powder for preventing adhesion in the material to be transferred or its dye receiving layer. By doing so, even if the temperature at the time of thermal transfer is further increased, adhesion between the thermal transfer sheet and the material to be transferred can be prevented, and more excellent thermal transfer can be performed. Particularly preferred is finely divided silica. Further, instead of or in combination with the above-mentioned inorganic powder such as silica, a resin as described above having good releasability may be added. A particularly preferred release polymer is a cured product of a silicone compound, for example, a cured product composed of an epoxy-modified silicone oil and an amino-modified silicone oil. Such a release agent preferably accounts for about 0.5 to 30% by weight of the weight of the dye receiving layer. The material to be transferred to be used may have the above-mentioned inorganic powder adhered to the surface of the dye receiving layer to enhance the anti-adhesion effect, and the release agent having excellent releasability as described above. You may provide the layer which consists of. Such a release layer has a sufficient effect at a thickness of about 0.01 to 5 μm, and can further improve dye receptivity while preventing adhesion to the dye receiving layer of the thermal transfer sheet. As the means for applying thermal energy used when performing thermal transfer using the thermal transfer sheet of the present invention as described above and the recording material as described above, any conventionally known applying means can be used, for example, a thermal printer (for example, 5 to 10 by controlling the recording time with a recording device such as Hitachi, Ltd., video printer VY-100, etc.
By applying heat energy of about 0 mJ / mm ^2,
The intended purpose can be sufficiently achieved. (Effect) According to the present invention as described above, as partially described above, the dye of the general formula (I) used in the construction of the thermal transfer sheet of the present invention has been used in the prior art thermal transfer sheet. Compared with sublimable dyes (molecular weight about 150 to 250),
Despite having a remarkably high molecular weight, it has a specific structure, and has a substituent at a specific position, so that it exhibits excellent heat transferability, dyeing property and color developing property to a transferred material, Further, after the transfer, it does not migrate in the material to be transferred and does not bleed out to the surface. Therefore, images formed by using the thermal transfer sheet of the present invention have excellent robustness, especially migration resistance and stain resistance, so that the sharpness of the formed image is impaired even after long-term storage, Or, it does not contaminate other articles at all and solves various problems of the prior art. 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. Example 1 The following structural formula 2.29 parts of the compound represented by the above is dissolved in 200 parts of 95% ethanol, and an aqueous solution prepared by dissolving 5 parts of anhydrous sodium carbonate in 50 parts of water is added to the resulting solution to prepare a mixed solution. Next, the following structural formula 2.48 parts of the compound represented by is dissolved in 50 parts of water, the resulting solution is added to the above mixed solution, and after sufficiently stirring, 100 parts of a 11.6% potassium ferrocyanide aqueous solution is gradually added, and in this state 15 Stir for minutes, filter and wash with pure water. When the filtrate became neutral, it was dried, the product was dissolved in ethyl acetate, and column purification was performed using ethyl acetate / heptane to obtain a dye of the following structural formula [dye No. 1 in Table 1 above]. Obtained. Example 2 In the same manner as in Example 1, the raw materials were changed and the dyes exemplified in Table 1 above were obtained. Example 3 An ink composition for forming a dye carrying layer having the following composition was prepared,
A 4.5 μm-thick polyethylene terephthalate film having a heat-resistant back surface was coated and dried to a dry coating amount of 1. g / m ² to obtain a thermal transfer sheet of the present invention. Dyes shown in Table 1 3 parts Polyvinyl acetoacetal resin 4.5 parts Methyl ethyl ketone 46.25 parts Toluene 46.25 parts Next, as a base sheet, synthetic paper (manufactured by Oji Yuka, YUPO FP
G # 150), a coating solution having the following composition was applied to one surface of the coating at a rate of 10.0 g / m ² when dried, and dried at 100 ° C. for 30 minutes to obtain a transfer-receiving material. Polyester resin (Vylon200, Toyobo) 11.5 parts Vinyl chloride-vinyl acetate copolymer (VYHH, UCC) 5.0 parts Amino-modified silicone (KF-393, 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 / cyclohexanone (weight ratio 4: 4: 2) 102.0 parts The thermal transfer sheet of the present invention and the material to be transferred are
Each dye-carrying layer and the dye-receiving surface face each other and are superimposed, and recording is performed with a thermal head from the back of the thermal transfer sheet under the conditions of a head applied voltage of 10 V and a printing time of 4.0 msec.
The results in Table 2 below were obtained. Comparative Example The dyes shown in Table 3 below were used as the dyes in Example 3, and the results of Table 3 below were obtained in the same manner as in Example 4 except for the above. However, the composition of the ink composition for forming the dye carrying layer was as follows. Dyes in Table 3 below 3 parts Polyvinyl acetoacetal resin 4.5 parts Methyl ethyl ketone 46.25 parts Toluene 46.25 parts The dyes in the above table are indicated by the numbers in Table 1 above. Table 3 Dyes Color density Fastness Color tone 1 0.99 × Blue 2 1.16 △ Blue 3 2.07 × Blue 4 1.12 △ Blue 5 1.02 × Purple The dyes in the above table are as follows. 1: CI Disperse Blue 14 2: CI Disperse Blue 134 3: CI Solvent Blue 63 4: CI Disperse Blue 26 5: CI Disperse Violet 4 The color density shown in Tables 2 to 3 above is the product of Macbeth Co. Densitometer RD-918. The fastness is ◎ when the recorded image is left in an atmosphere of 50 ° C. for a long time and the image sharpness does not change, and the white paper is not colored even if the surface is rubbed with a white paper. Is shown and the white paper is slightly colored, and the sharpness is lost and the white paper is colored, and the image is unclear and the white paper is marked with X.

Claims (1)

(57) [Claims] It comprises a substrate sheet and a dye-carrying layer formed on one surface of the substrate sheet, and the dye contained in the dye-carrying layer is a dye represented by the following general formula (I). Heat transfer sheet. [However, R ₁ in the above formula is CONHR, CONRR ′, NHCOR, SO ₂ NH
R, NHSO ₂ R (R and R ′ represent an alkyl group in which a hydrogen atom may be substituted with a fluorine atom, a cycloalkyl group or an aryl group which may have a substituent), R ₂ and
R ₃ represents a halogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, an acylamino group, an aminocarbonyl group, an alkylaryl group or an aryl group, and R ₄ and R ₅ represent an alkyl group which may have a substituent or an aralkyl. Represents a group, an aryl group or a hydrogen atom, and A represents an atomic group constituting a naphthalene ring as a whole, which may have nothing or may have a substituent as described above. ] 2. NHCOR in which R ₁ is in the 1 position when there is no A
The thermal transfer sheet according to claim (1), wherein R is as defined above. 3. When A constitutes a naphthalene ring as a whole, R ₁ is a CONHR or CONRR ′ group (R and R ′ are as defined above) present at the 1-position, and the compound according to claim (1). Thermal transfer sheet. 4. The thermal transfer sheet according to claim (1), wherein R ₄ and / or R ₅ is an alkyl group having a polar group.