JP2880159B2 - Thermal transfer sheet - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a thermal transfer sheet, and more particularly, to a novel thermal transfer sheet capable of easily providing a recording material having excellent robustness to a material to be transferred. The purpose is to do. (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 transferable agent that can be attached, for example, laid on a polyester woven fabric or the like, and applying thermal energy in a pattern from the back of the thermal transfer sheet,
A sublimation transfer method for transferring a sublimable dye to a material to be transferred has been performed. (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, using a polyester sheet or a transfer material provided with a dye receiving layer on paper, and using delicate characters and graphics on these transfer materials Alternatively, in the case of forming a photographic image, the application of thermal energy is required to be extremely short in seconds or less, and therefore, the sublimable dye and the material to be transferred are not sufficiently heated in such a short time. 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. However, there is a problem in that the dye migrates with time or bleeds on the surface, so that the formed image is disturbed, becomes unclear, or stains 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.As a result of the conventional sublimation printing method of polyester woven fabric and the like, the surface of the woven fabric is not smooth, so that the heat transfer sheet and the material to be transferred are used. It is indispensable that the dye used does not adhere sufficiently to a certain woven fabric, and that the dye to be used is sublimable or vaporizable (that is, a property capable of transferring the space existing between the thermal transfer sheet and the woven fabric). Was
When a transfer target material is a polyester sheet or surface-treated paper with a smooth surface, the thermal transfer sheet and the transfer target material adhere sufficiently to each other during thermal transfer, so only sublimation and vaporization of the dye are absolutely necessary conditions. Rather, it is also very important that the dye can be transferred by heat to the interface between the two in contact, and the heat transferability of such an interface is greatly affected by the melting point, inorganic and organic properties of the dye used. Knowledge of
By selecting a dye having an appropriate melting point and an inorganic / organic value (hereinafter referred to as I / O value), it is possible to use a dye having a molecular weight that is considered to be unusable by conventional common sense. Have good heat transfer properties. By using a thermal transfer sheet carrying a dye selected according to the melting point and I / O value of 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. However, they have found that a recorded image having high density and excellent various fastnesses is formed, thereby completing the present invention. (Means for Solving the Problems) That is, the present invention relates to a method for recording an image on a non-fibrous transfer material, comprising a base sheet and a dye-carrying layer provided on one surface of the base sheet. In the thermal transfer sheet, the dye contained in the dye-carrying layer is an anthraquinone-based dye represented by the following general formula. [However, R ₁ , R ₂ and R ₃ in the formula represent a molecular weight of the entire dye.
Is a substituted or unsubstituted alkyl group which exceeds 350, X represents O or NH, and R ₁ and R ₃ may be hydrogen. Next, the present invention will be described in more detail. In the present invention, in the anthraquinone-based dye having a basic structure as shown in the above general formula, R1, R2 and R3 in the general formula, particularly R2 in the entire dye, When the molecular weight is selected to be more than 350, preferably 380 or more, it is out of the selection criteria based on the molecular weight of the conventional thermal transfer dye, but R1, R2 and R
3, especially as the carbon number of R2 increases, the melting point of the dye or I
It has been found that the / O value tends to decrease, and when used as a thermal transfer dye, the heat transfer rate is rather increased, and an image with excellent fastness is obtained after transfer. The anthraquinone dye represented by the above general formula is obtained by a conventionally known production method. In the anthraquinone dye of the general formula, R1,
The group represented by R2 and R3 is a linear, branched or cyclic substituted or unsubstituted alkyl group, for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a cyclohexyl group, Hexyl group, heptyl group,
Alkyl groups such as octyl, decyl, undecyl, lauryl, tridecyl, tetradecyl, pentadecyl, cetyl, heptadecyl; ethanol, propanol, butanol, pentanol, heptanol, octanol, etc. Alkanol group; methoxymethyl group, methoxyethyl group, methoxypropyl group,
A methoxybutyl group, a methoxypentyl group, a methoxyhexyl group, a methoxyheptyl group, a methoxyoctyl group, or an alkoxyalkyl group having another alkoxy group such as ethoxy, propoxy, butoxy, pentoxy instead of these methoxy groups; N-methyl N-alkylamino such as ethyl, propyl, butyl, pentyl, hexyl, octyl and the like having an alkylamino group such as amino, N-ethylamino, N-propylamino, N-butylamino, N-petylamino and N-hexylamino And an alkyl group. Among these alkyl groups, R1 and R3
As a hydrogen atom or a C1-C4 alkyl group,
In addition, it is preferable to select an alkyl group of C4 or more as R2. In the anthraquinone dye of the present invention represented by the above general formula, in determining R1, R2 and R3 in the formula, R1, R2 and R3 such that the molecular weight of the entire dye exceeds 350, preferably 380 or more. Must be selected, and it is also preferable that the I / O value be 1.2 or less. The "I / O" value referred to in the present invention is based on Yoshio Koda's "Organic Conceptual Diagram-Basics and Applications-" (Sankyo Publishing). That is, according to the detailed study of the present inventors, in the dye of the general formula, by selecting an alkyl group having a large number of carbon atoms as the substituents R1, R2 and R3, particularly R2, the molecular weight of the dye is increased, Molecular weight over 350 or 380
However, in the dyes of the above general formula, unlike the conventional general idea, the melting points of these dyes tend to decrease, and when used as dyes for thermal transfer, a thermal head or the like is used. It has been found that the heat transfer speed of the dye from the thermal transfer sheet to the material to be transferred is increased even by heating for a very short time by the above method, and that an image having excellent fastness is provided. Further, as R1, R2 and R3, particularly R2, use of an alkyl group having a large number of carbon atoms, the I / O value decreases, and those having a polar group such as a hydroxyl group, an ether bond, or an amide bond as the alkyl group. Although the melting point is increased by the use, in the dyes of the present invention, R1, R2 and R3, especially
When adjusting the I / O value of the dye to be in the range of 1.2 or less by selecting R2, the dye having such an appropriate I / O value is
It has been found to be very useful as a dye for thermal transfer. That is, in the case of a dye for thermal transfer, as described above, heat transfer to the material to be transferred is required in a very short time, but the dye of the present invention is methyl ethyl ketone, ethanol used in preparing a thermal transfer sheet. The solubility in general-purpose organic solvents such as toluene, isopropyl alcohol, tetrahydrofuran, cyclohexanone, dimethylformamide, formamide, dimethylsulfoxide and the like or a mixed solvent thereof is remarkably improved, and in the dye-carrying layer formed on the thermal transfer sheet, Can be present in a crystalline state or in a low state, and the dye can be easily transferred to the material to be transferred with a significantly smaller amount of applied heat as compared to the existing state with high crystallinity as in the case of the conventional dye. Was something. 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-mentioned dye may be any one having conventionally known heat resistance and strength, for example, 0.5 to 50 μm, preferably 3 to 50 μm. Paper having a thickness of about 10 μm, various kinds of processed paper, polyester films, polystyrene films, polypropylene films, polysulfone films, polycarbonate films, polyvinyl alcohol films, cellophane, etc., and particularly preferred are polyester films. 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 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 thereof include ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxycellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, and vinegar. Cellulose resins such as cellulose butyrate, and vinyl resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl pyrrolidone, and polyacrylamide, and polyesters are preferred in terms of heat resistance, dye migration, 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 a suitable solvent and dissolving or dispersing each component to prepare a coating solution or ink for forming a supporting layer. Is applied and dried on the above-mentioned base material sheet to form. In particular, the above-mentioned dye, methyl ethyl ketone used in the preparation of the transfer sheet, ethanol, toluene, isopropyl alcohol, tetrahydrofuran, cyclohexanone, dimethylformamide, formamide, dimethylsulfoxide and the like, or a mixed solvent thereof, compared to conventional dyes High solubility, eg 3% 5% preferred
Because it has a high solubility, it is easy to prepare an ink for forming a dye-carrying layer, and because the dye exists in a dissolved state or a state close to it in the support layer after forming the dye-carrying layer. It has the advantage of exhibiting an excellent heat transfer rate with a small amount of heat energy. The supporting layer thus formed has a thickness of 0.2 to 5.0 μm, preferably 0.4 to 5.0 μm.
The dye in the carrier layer is 5 to 70% by weight, preferably 10 to 60% by weight of the carrier layer.
It is preferably present in an amount of weight percent. Although the thermal transfer sheet of the present invention as described above is sufficiently useful as it is for thermal transfer, an anti-adhesion layer, that is, a release layer may be further provided on the surface of the dye-carrying layer. Accordingly, it is possible to prevent adhesion between the thermal transfer sheet and the material to be transferred at the time of thermal transfer, to use a higher thermal transfer temperature, and to form an image with a further excellent density. As this release layer, even if only an anti-adhesive inorganic powder is simply adhered, 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, from 0.01 to It can be formed by providing a release layer of 5 μm, preferably 0.05 to 2 μm. The inorganic powder or the releasing polymer as described above has a sufficient effect even if it is included in the dye-supporting 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 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 resins such as polyethylene and polypropylene; halogenated polymers such as polyvinyl chloride and polyvinylidene chloride; vinyl polymers such as polyvinyl alcohol, polyvinyl acetate and polyacrylic ester; and polyester resins such as polyethylene terephthalate and polybutylene terephthalate. , Polystyrene resins, polyamide resins, copolymer resins of olefins such as ethylene and propylene with other vinyl monomers, cellulose resins such as ionomers, cellulose diacetate and cellulose triacetate, fibers made of polycarbonate, polysulfone, polyimide, etc. , Woven fabric, film, sheet, molded product and the like. Particularly preferred is a sheet or film made of polyester or a processed paper provided with a polyester layer. Further, paper, metal, glass and other non-dyeable transfer receiving materials may be coated and dried with a solution or dispersion of the above-described dyeable resin on the recording surface, or may be made of such a resin. 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 receiving layer thus formed may be formed from a single material or a plurality of materials, and may further contain various additives within a range not to impair the intended purpose. Of course. Such a dye-receiving layer may be of any thickness, but generally has a thickness of 5 to 50 .mu.m. Further, such a dye receiving layer is preferably a continuous coating, but may be formed as a discontinuous coating using a resin emulsion or a resin dispersion. Such a material to be transferred is basically as described above, and can be used as it is, but 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 is used in an amount of about 0.5 to 3% by weight of the dye receiving layer.
The proportion occupying 0% by weight is good. The transfer material to be used is, on the surface of the dye receiving layer,
An inorganic powder as described above may be adhered to enhance the anti-adhesion effect, or a layer made of a release agent having excellent release properties as described above may be provided. Such a release layer has a sufficient effect at a thickness of about 0.01 to 5 μm, and can further improve the 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, and for example, a thermal printer (for example, Toshiba Corporation
5-100m by controlling the recording time by a recording device such as a thermal printer TN-5400
By applying thermal energy of about J / mm ² , the intended purpose can be sufficiently achieved. (Function / Effect) As described above, the dye used in the present invention has excellent heat transferability to the material to be transferred, similarly to conventional low molecular weight dyes, for example, dyes having a molecular weight of 300 or less. The fastness of an image with such a dye, especially the sublimation resistance and the light resistance, are remarkably excellent due to the large molecular weight. Therefore, the thermal transfer sheet of the present invention has solved various problems of the prior art. Next, the above will be described more specifically with reference to examples and comparative examples. In the description, parts and% are based on weight unless otherwise specified. Example An ink composition for forming a dye carrying layer having the following composition was prepared,
The thermal transfer sheet of the present invention was obtained by coating and drying on a 9 μm-thick polyethylene terephthalate film having a heat-treated rear surface so that the dry coating amount was 1.0 g / m ² . Dyes in Table 1 below (Examples) 1 part Polybutyral resin 4.5 parts Methyl ethyl ketone 23.35 parts Toluene 25.35 parts Dimethylformamide 43.80 parts Next, synthetic paper (Yojipo FP, manufactured by Oji Oil Chemical Co., Ltd.) was used as the base sheet.
G # 150), a coating solution having the following composition was applied to one surface of the coating at a rate of 4.5 g / m ² when dried, and dried at 100 ° C. for minutes to obtain a transfer-receiving material. Polyester resin (Vylon103, Toyobo, Tg = 47 ° C) 0.8 parts EVA polymer plasticizer (Elvaloy 741P, Mitsui Polychemicals, Tg = -37
C) 0.2 parts Amino-modified silicone (KF-857, Shin-Etsu Chemical Co., Ltd.) 0.04 parts Epoxy-modified silicone corn (KF-103, Shin-Etsu Chemical Co., Ltd.) 0.04 parts Methyl ethyl ketone / toluene / cyclohexanone (weight ratio 4: 4: 2) 9.0 The above-described thermal transfer sheet of the present invention and the above-described transfer-receiving material,
The respective dye-carrying layers and the dye-receiving surface face each other and are superimposed, and recording is performed with a thermal head under the conditions of a head applied voltage of 10 V and a printing time of 4.0 msec. From the back of the thermal transfer sheet.
The results shown in Table 1 below were obtained. Comparative Example The dyes in Table 1 described below were used as the dyes in the examples, and the results in the following table 1 were obtained in the same manner as in the examples except for the dyes.
However, the composition of the ink composition for forming a dye carrying layer was as follows. Dyes shown in Table 1 below 3 parts Polybutyral resin 4.5 parts Methyl ethyl ketone 46.25 parts Toluene 46.25 parts The color density in Table 1 is a value measured by Tenbeth Meter RD-918 manufactured by Macbeth Corporation in the United States. The fastness was evaluated as ◎ when the recorded image was left in an atmosphere of 50 ° C for a long time and the sharpness of the image did not change and the white paper was not colored even if the surface was rubbed with white paper. Those that were lost and slightly colored white paper were marked with ○, those that lost sharpness and colored white paper were marked with Δ, and those where the image was unclear and the white paper was significantly colored were marked with x.

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Claims (1)

(57) [Claims] A heat transfer sheet for recording an image on a non-fibrous transfer material, comprising a base sheet and a dye support layer provided on one surface of the base sheet, the dye contained in the dye support layer, A thermal transfer sheet comprising an anthraquinone dye represented by the following general formula. [However, R ₁ , R ₂ and R ₃ in the formula represent a molecular weight of the entire dye.
Is a substituted or unsubstituted alkyl group which exceeds 350, X represents O or NH group, and R ₁ and R ₃ may be hydrogen atoms. ) 2. The thermal transfer sheet according to claim ₁ , wherein R ₁ , R ₂ and R ₃ are selected such that the total molecular weight of the dye is 380 or more. 3. R ₁ , R ₂ and R ₃ are those having an inorganic / organic value of 1.
Claims (1) selected to be 2 or less
Item 6. The thermal transfer sheet according to item 1.