JP5983257B2 - Thermal transfer sheet - Google Patents

Description

  The present invention relates to a thermal transfer sheet.

  As a method of forming an image using thermal transfer, a dye-receiving layer is provided on a sublimation type thermal transfer sheet in which a sublimable dye is supported on a base material such as a plastic film and another base material such as paper or plastic film. A sublimation thermal transfer method is known in which a thermal transfer image receiving sheet is superposed on each other to form a full color image. Since this method uses sublimation dyes as color materials, it has excellent reproducibility and gradation of intermediate colors, and can express full-color images exactly as they are on a thermal transfer image-receiving sheet. It is applied to color image formation for computers. The image is of a high quality comparable to a silver salt photograph.

  In the dye layer of such a sublimation type thermal transfer sheet, the sublimation dye contained in the dye layer is well held by the binder resin during storage of the thermal transfer sheet, and the sublimation dye from the binder resin is good during thermal transfer. In other words, high storage stability and dye transfer efficiency are required.

  As a binder resin that focuses on storage stability, a butyral or acetal resin is known (see Patent Document 1). A dye layer containing a butyral or acetal resin as a binder resin is excellent in storage stability, but has a problem that the dye transfer efficiency is low and the printing density is low. Therefore, when these binder resins are used, (i) the amount of the dye layer applied is increased to increase the content of the sublimable dye contained in the dye layer, or (ii) the dye of the thermal transfer sheet It is necessary to improve the print density by a method such as increasing the mass ratio (D / B ratio) of the sublimable dye / binder resin in the layer.

  However, when the coating amount of the above (i) dye layer is increased, a large amount of sublimation dye that does not move to the thermal transfer image-receiving sheet side remains in the dye layer, which is not preferable in terms of cost. . Also, (ii) when the D / B ratio is increased until a sufficient printing density is achieved, the butyral or acetal binder resin cannot retain the sublimable dye and the storage stability is significantly reduced. To do. When storage stability is reduced, when the thermal transfer sheet is stored in a wound state, the dye layer and the back layer provided on the opposite side of the substrate come into contact with each other, so that the dye layer is sublimated from the back layer. The dye migrates (kick), causing a decrease in sheet transportability and a decrease in the function of the back layer. In addition, when stored in a high-temperature and high-humidity environment, the dye deposits on the surface of the dye layer, and during printing, the deposited dye comes into contact with the unprinted portion, resulting in soiling that contaminates the unprinted portion. It will cause various problems.

  Cellulose resins such as cellulose acetate propionate and ethyl cellulose are known as binder resins whose main purpose is to improve dye transfer efficiency. However, these binder resins whose main purpose is to improve dye transfer efficiency are excellent in dye transfer efficiency, but have low storage stability, especially when the coating amount of the dye layer is reduced or the D / B ratio is increased. In such a case, the storage stability is lowered, and the above problem is caused.

  In addition, if only focusing on improving the printing density, it is sufficient to include a high-concentration sublimation dye in the dye layer. However, the high-concentration dye is difficult to be retained in the binder resin, and the dye layer is stored during storage. In general, those having a property of being easily deposited on the surface of the glass. That is, the improvement in density and dye storage stability are in a trade-off relationship, and a dye layer that can satisfy both of them is not known at present.

JP 2009-286060 A

  The present invention has been made in such a situation, and it is a main object of the present invention to provide a thermal transfer sheet capable of forming an image with a high printing density while preventing occurrence of kicks and scumming.

The present invention for solving the above problems is a thermal transfer sheet in which a yellow dye layer is provided on one side of a substrate and a back layer is provided on the other side of the substrate, the yellow dye layer comprising A binder resin and a sublimable dye, and the binder resin contains nitrocellulose. The sublimable dye includes a sublimable dye represented by the following general formula (1), Solvent Yellow 93, The yellow dye layer contains 55% by mass of the sublimable dye represented by the following general formula (1) with respect to the total mass of the sublimable dye represented by the following general formula (1) and Solvent Yellow 93. It is contained at a ratio of 85% by weight or less.

Further, the yellow dye layer may further contain any one or both of sublimable dyes represented by the following general formula (2) and the following general formula (3).

  (R1 in the general formula (2) represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group, and R2 represents a hydrogen atom, a halogen atom, an optionally substituted alkoxy group, or optionally substituted. An alkylthio group or an optionally substituted arylthio group, wherein R3 represents a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted alkylaminocarbonyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group; Represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a heterocyclic group or a halogen atom.)

  (R1 in the general formula (3) represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group, and R2 represents a substituted or unsubstituted aralkyl group. Unsubstituted alkyl group, substituted or unsubstituted aralkyloxycarbonyl group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted alkylaminocarbonyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkylamino Represents a sulfonyl group, a substituted or unsubstituted cycloalkyl group, a cyano group, a nitro group or a halogen atom.)

  The total solid content of the sublimable dyes represented by the general formula (2) and the general formula (3) with respect to the total solid content of all sublimable dyes contained in the yellow dye layer is 33% by mass or less. There may be.

  The sublimable dye represented by the general formula (2) is a sublimable dye represented by the following general formula (2-1), and the sublimable dye represented by the general formula (3) is represented by the following general formula. It may be a sublimable dye represented by (3-1) and / or the following general formula (3-2).

  According to the thermal transfer sheet of the present invention, it is possible to form an image having a high printing density while preventing the occurrence of kicks and background stains.

It is a schematic sectional drawing which shows an example of the thermal transfer sheet of this invention. It is a schematic sectional drawing which shows an example of the thermal transfer sheet of this invention.

  Hereinafter, the thermal transfer sheet of the present invention will be described in detail. FIG. 1 is a schematic sectional view showing an example of the thermal transfer sheet of the present invention.

  As shown in FIG. 1, the thermal transfer sheet 10 of the present invention has a configuration in which a yellow dye layer 2 </ b> Y is provided on one surface of a substrate 1 and a back layer 5 is provided on the other surface of the substrate 1. Here, in the thermal transfer sheet 10 of the present invention, the yellow dye layer 2Y contains a binder resin and a sublimation dye, and the binder resin contains nitrocellulose. The sublimation dye includes a sublimation dye represented by the following general formula (1) and Solvent Yellow 93, and the yellow dye layer 2Y includes a sublimation dye represented by the following general formula (1), It is characterized by containing a sublimable dye represented by the following general formula (1) in a proportion of 55% by weight or more and 85% by weight or less with respect to the total mass of Solvent Yellow 93. In FIG. 1, the primer layer 3 is provided between the base material 1 and the yellow dye layer 2Y. However, the primer layer 3 has an arbitrary configuration in the thermal transfer sheet 10 of the present invention.

(Base material)
The substrate 1 used in the thermal transfer sheet 10 of the present invention is not particularly limited as long as it has a certain degree of heat resistance and strength, and a conventionally known material can be appropriately selected and used. As such a substrate 1, for example, a polyethylene terephthalate film, a 1,4-polycyclohexylenedimethylene terephthalate film, a polyethylene naphthalate film, a polyphenylene sulfide having a thickness of about 0.5 μm to 50 μm, preferably about 1 μm to 10 μm. Film, polystyrene film, polypropylene film, polysulfone film, aramid film, polycarbonate film, polyvinyl alcohol film, cellophane, cellulose derivatives such as cellulose acetate, polyethylene film, polyvinyl chloride film, nylon film, polyimide film, ionomer film, etc. . Furthermore, each of these materials can be used alone, but may be used as a laminate in combination with other materials.

  As described later, by providing a primer layer between the base material 1 and the yellow dye layer 2Y, the adhesion between the base material 1 and the yellow dye layer 2Y can be improved. In addition, the base material 1 that has been subjected to various adhesion treatments may be used. Adhesion treatment includes known resin surface modifications such as corona discharge treatment, flame treatment, ozone treatment, ultraviolet treatment, radiation treatment, surface roughening treatment, chemical treatment, plasma treatment, low temperature plasma treatment, primer treatment, and grafting treatment. The technology can be applied as it is. Two or more of these treatments can be used in combination. The primer treatment can be performed, for example, by applying a primer solution to an unstretched film at the time of film formation by melt extrusion of a plastic film and then stretching the film.

(Yellow dye layer)
As shown in FIG. 1, a yellow dye layer 2 </ b> Y is provided on the substrate 1. The yellow dye layer 2Y contains a sublimable dye and a binder resin. Hereinafter, the sublimable dye and the binder resin will be specifically described.

<Sublimation dye>
The sublimation dye contained in the yellow dye layer 2Y includes a sublimation dye represented by the general formula (1) and Solvent Yellow 93 as essential dyes. Hereinafter, the sublimable dye represented by the general formula (1) and Solvent Yellow 93 may be collectively referred to as “two kinds of dyes”.

  In the present invention, due to the synergistic effect of the sublimable dye represented by the general formula (1), Solvent Yellow 93, and nitrocellulose contained in the binder resin described later, the concentration is increased and the occurrence of kicks and dirt is generated. The prevention effect is achieved.

  The sublimable dye represented by the general formula (1) has a property of giving a high density to the obtained printed matter even if the dye concentration of yellow is high and the content thereof is small. As will be described later, since the yellow dye layer 2Y contains nitrocellulose having a high dye transfer efficiency, the sublimation dye represented by the general formula (1) can be used without waste, such as a thermal transfer image receiving sheet. It can be transferred onto a transfer medium. Therefore, the concentration can be improved by the synergistic effect of the sublimable dye represented by the general formula (1) and nitrocellulose.

  In the present invention, Solvent Yellow 93 is contained in the yellow dye layer 2Y together with the sublimable dye represented by the general formula (1). Solvent Yellow 93 has the property that the amount of kick can be dramatically reduced by adding a small amount to the yellow dye layer 2Y. Specifically, if the content of Solvent Yellow 93 with respect to “two kinds of dyes” is 15% by mass or more, a dramatic reduction effect of the kick amount can be achieved regardless of the blending ratio of Solvent Yellow 93. The amount of kick when the yellow dye layer is a combination of a sublimable dye other than Solvent Yellow 93 and the sublimable dye represented by the general formula (1) is as follows. In addition to the value obtained by multiplying the kick amount of the sublimable dye represented by the general formula (1) by the blend ratio of the sublimable dye represented by the general formula (1), and other than Solvent Yellow 93 The total amount of the value obtained by multiplying the kick amount of the sublimable dye by the blending ratio of the other sublimable dye is only slightly improved.

  For example, the kick amount when the yellow dye layer containing only the sublimable dye represented by the general formula (1) is “10”, the kick amount of other sublimable dyes other than Solvent Yellow 93 is “4”, Assuming that the mixing ratio of each sublimation dye is “50% by mass”, the kick amount of the yellow dye layer is slightly improved to “7” (10 × 0.5 + 4 × 0.5 = 7). It ’s only the amount of kicks I made. Further, when it is assumed that the blending ratio of other sublimation dyes assumed to be “4” is 20 mass%, the kick amount of the yellow dye layer is “8.8” (10 × 0 .8 + 4 × 0.2) is a slightly improved value, and the kick amount decreases as the blending ratio of other sublimable dyes decreases.

  On the other hand, Solvent Yellow 93, if the blending ratio with respect to the total mass of the sublimable dye represented by the general formula (1) is 15% or more, regardless of the blending ratio of Solvent Yellow 93, the yellow dye layer 2Y The amount of kicks can be dramatically reduced. For example, when it is assumed that the kick amount of Solvent Yellow 93 is “4” as in the sublimation dyes other than Solvent Yellow 93 described above, if the blending ratio of Solvent Yellow 93 is 15% by mass or more, yellow The kick amount of the dye layer 2Y can be brought close to “4” as it is.

  In the yellow dye layer 2Y in which both the sublimable dye represented by the general formula (1) and the Solvent Yellow 93 are contained in the yellow dye layer 2Y, the above general amount with respect to the total mass of the “two kinds of dyes” When the content of the sublimable dye represented by the formula (1) is less than 55% by mass, the sublimable dye is likely to be rapidly deposited on the surface of the yellow dye layer 2Y. This causes problems such as generation of ground stains that contaminate the unprinted portion due to the contact of the dye with the unprinted portion. On the other hand, if it exceeds 85 mass%, the content of Solvent Yellow 93 will be less than 15 mass%, and the kick amount cannot be dramatically reduced.

  Therefore, in the present invention, the content of the sublimable dye represented by the general formula (1) with respect to the total mass of the “two kinds of dyes” is defined within the range of 55% by mass to 85% by mass. . According to the yellow dye layer 2Y in which the blending amount of “two kinds of dyes” is defined within this range, the printed matter obtained by the thermal transfer sheet 10 of the present invention can be obtained while preventing the occurrence of kicks and soiling. The kick amount can be greatly reduced while giving a high print density.

  The yellow dye layer 2Y may contain other known yellow dyes as sublimation dyes together with the “two kinds of dyes” described above. Examples of other yellow dyes include quinophthalone dyes represented by the following general formula (2) and pyridone azo dyes represented by the following general formula (3). Specific examples of the dye represented by the following general formula (2) include dyes represented by the following general formula (2-1). Moreover, as a specific dye shown by the following general formula (3), the dye shown by the following general formula (2-1) can be illustrated.

  (R1 in the general formula (2) represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group, and R2 represents a hydrogen atom, a halogen atom, an optionally substituted alkoxy group, or optionally substituted. An alkylthio group or an optionally substituted arylthio group, wherein R3 represents a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted alkylaminocarbonyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group; Represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a heterocyclic group or a halogen atom.)

  (R1 in the general formula (3) represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group, and R2 represents a substituted or unsubstituted aralkyl group. Unsubstituted alkyl group, substituted or unsubstituted aralkyloxycarbonyl group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted alkylaminocarbonyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkylamino Represents a sulfonyl group, a substituted or unsubstituted cycloalkyl group, a cyano group, a nitro group or a halogen atom.)

  There is no particular limitation on the total mass of the “two types of dyes” with respect to the total solid content of the sublimation dye, but the total mass of the “two types of dyes” with respect to the solid content of the sublimation dye is less than 67% by mass. In some cases, the concentration tends to decrease slightly. Therefore, in consideration of this point, the total mass of the “two kinds of dyes” is preferably 67% by mass or more based on the total solid content of the sublimable dye. In addition, even if the total mass of the “two types of dyes” is out of this range, the content of the sublimable dye represented by the general formula (1) with respect to the total mass of the “two types of dyes” is 55 masses. According to the yellow dye layer 2Y specified within the range of not less than 85% and not more than 85% by mass, it is possible to prevent the occurrence of kicks and soiling. Further, the sublimable dye represented by the general formula (1) can improve the concentration with a small amount of content, and even if the total mass of the “two kinds of dyes” is less than 67% by mass, it is sufficient. It is possible to improve the concentration.

<Binder resin>
The yellow dye layer 2Y contains a binder resin for holding the sublimable dye together with the sublimable dye including the above-mentioned “two kinds of dyes”. In the present invention, the binder resin includes an essential component. Contains nitrocellulose. Nitrocellulose has high dye retention of sublimation dyes, and the mass ratio (D / B ratio (sublimation dye / binder resin) of the sublimation dye containing the above “two types of dyes” and the binder resin containing nitrocellulose. Even if)) becomes high, it is possible to prevent the occurrence of soiling, kick and back.

  Also, since nitrocellulose has good dye transfer efficiency, a high printing density can be obtained even when the coating amount is reduced to increase the dye transfer efficiency.

  The viscosity of the nitrocellulose is not particularly limited, but when the yellow dye layer 2Y contains nitrocellulose having a viscosity of less than 1/16 according to JIS K-6703, the storage stability tends to decrease. On the other hand, when the yellow dye layer 2Y contains nitrocellulose having a viscosity of more than 120 according to JIS K-6703, there is a possibility that ink mist or the like may be generated when the yellow dye layer 2Y is formed.

  In consideration of this point, the yellow dye layer 2Y preferably contains 1/16 or more and 120 or less nitrocellulose in viscosity according to JIS K-6703, and contains 1/8 or more and 120 or less nitrocellulose. More preferably. In other words, the viscosity according to JIS K-6703 (solution concentration 25%) is 1.0 second to 14.9 seconds, the viscosity according to JIS K-6703 (solution concentration 20%) is 6.0 seconds to 8.0 seconds, Or the viscosity (solution concentration 12.2%) according to JIS K-6703 is preferably 4.0 seconds to 140.0 seconds. By containing nitrocellulose having a viscosity according to JIS K-6703 in this range in the yellow dye layer 2Y, the storage stability can be further improved, and ink mist is generated when the yellow dye layer 2Y is formed. Can be prevented.

  As the nitrocellulose having a viscosity within the above range, a commercially available product can be used as it is. Examples of the viscosity within the above range include, for example, the types and viscosity symbols specified in JIS K-6703 manufactured by Taihei Chemicals Co., Ltd., H1 / 16, H1 / 8, L1 / 8, H1 / 4. Examples include L1 / 4, H1 / 2, H1 ″, H5 ″, H20, H60, and H120. In addition, DHX3-5, DHX5-10, DHX8-13, DHX11-16, DHX30-50, DHX40-70, DHL25-45, DHL120-170, H20 (160-210) manufactured by Inabata Sangyo Co., Ltd. , DHM10-25, SL-1, DLX3-5, DLX5-8, DLX8-13, DLX30-50, etc. can also be used.

  Nitrocellulose preferably has a nitrogen content (degree of nitrification) of 10%. In consideration of handling safety, the nitrogen content is preferably 12.3% or less. Inclusion of nitrocellulose having a nitrogen content of 10% or more in the yellow dye layer 2Y is expected to further improve the dye transfer efficiency.

  The yellow dye layer 2Y may contain a binder resin other than nitrocellulose as long as the gist of the present invention is not hindered. Other binder resins include conventionally known binder resins contained in the dye layer, for example, cellulose resins such as ethyl cellulose resin, hydroxyethyl cellulose resin, ethyl hydroxy cellulose resin, methyl cellulose resin, cellulose acetate resin, polyvinyl alcohol resin, polyacetic acid Examples include vinyl resins, polyvinyl butyral resins, polyvinyl acetal resins, vinyl resins such as polyvinyl pyrrolidone, acrylic resins such as poly (meth) acrylate and poly (meth) acrylamide, polyurethane resins, polyamide resins, and polyester resins. It is done.

  There is no particular limitation on the content of nitrocellulose with respect to the total solid content of all binder resins including nitrocellulose, but when the content of nitrocellulose with respect to the total solid content of all binder resins is less than 70% by mass. In some cases, the sublimable dye containing the “two kinds of dyes” cannot be sufficiently retained. Also, the dye transfer efficiency tends to decrease. Considering this point, the content of nitrocellulose with respect to the total solid content of the binder resin is preferably 70% by mass or more. There is no limitation in particular about an upper limit, and it is 100 mass%.

  In the present invention, the concentration is improved by the sublimation dye containing the “two kinds of dyes”. For the purpose of further improving the concentration, the sublimation dye containing the “two kinds of dyes” It is preferable to increase the mass ratio (D / B ratio (sublimation dye / binder resin)) (hereinafter referred to as D / B ratio) with the binder resin containing nitrocellulose. Specifically, the D / B ratio is preferably 2.0 or more. The sublimable dye is the total mass of all sublimable dyes including “two kinds of dyes”, and the binder resin means the total mass of all binder resins including nitrocellulose. When the D / B ratio is 2.0 or more, the total mass of the “two kinds of dyes” relative to the total solid content of the sublimable dye is preferably 67% by mass or more. The content of nitrocellulose with respect to the total solid content is preferably 70% by mass or more.

  The preferable upper limit value of the D / B ratio is not particularly limited, but when the D / B ratio exceeds 3.5, the amount of the sublimation dye with respect to the binder resin is too large, and the binder resin containing nitrocellulose In some cases, the sublimable dye containing the “two kinds of dyes” cannot be retained and the storage stability is lowered. Therefore, considering this point, the D / B ratio is preferably in the range of 2.0 to 3.5.

The thickness of the yellow dye layer 2Y is not particularly limited. However, when the thickness of the yellow dye layer 2Y is less than 0.13 g / m ² , the effect of increasing the concentration tends to decrease. Further, when the thickness of the yellow dye layer 2Y exceeds 0.50 g / m ² , the dye transfer efficiency tends to be lowered. Therefore, considering this point, the thickness of the yellow dye layer 2Y is preferably 0.13 g / m ² or more 0.50 g / m ² or less at the time of drying.

  The yellow dye layer 2Y may contain additives such as inorganic fine particles and organic fine particles in addition to sublimable dyes and nitrocellulose. Examples of the inorganic fine particles include carbon black, aluminum, and molybdenum disulfide. Examples of the organic fine particles include polyethylene wax and silicone resin fine particles. Further, the yellow dye layer 2Y may contain other release agents within a range that does not interfere with the gist of the present invention. Examples of other release agents include conventionally known silicones and phosphate esters.

  There is also no particular limitation on the method of forming the yellow dye layer 2Y. Sublimation dyes containing “two kinds of dyes”, binder resins containing nitrocellulose, and additives as necessary, such as mold release agents and organic fine particles In addition, a coating solution dissolved in an appropriate organic solvent such as toluene, methyl ethyl ketone, isopropyl alcohol, ethanol, cyclohexanone, or DMF, or dispersed in an organic solvent or water is subjected to gravure printing, die coating printing, bar coating printing, screen printing, Alternatively, it can be formed by applying and drying by means of reverse roll coating printing using a gravure plate.

  In the embodiment shown in FIG. 1, only the yellow dye layer 2Y is provided on the base material 1. For example, as shown in FIG. 2, dye layers containing different sublimation dyes are used as the same base material. It is also possible to repeatedly provide them on the same surface in the surface order. FIG. 2 shows a thermal transfer sheet 10 having a configuration in which a yellow dye layer 2Y, which is an essential layer in the present invention, and a magenta dye layer 2M and a cyan dye layer 2C, which are optional dye layers, are provided in the surface order. It is a schematic sectional drawing which shows an example. Further, in the structure shown in FIG. 1, the transfer property (not shown) is on the same surface as the yellow dye layer 2Y, or in the structure shown in FIG. 2, on the same surface as the yellow dye layer 2Y, magenta dye layer 2M, and cyan dye layer 2C. A protective layer may be provided.

(Primer layer)
As shown in FIGS. 1 and 2, a primer layer 3 is preferably provided between the substrate 1 and the yellow dye layer 2Y. By providing the primer layer 3, the adhesion between the substrate 1 and the yellow dye layer 2Y can be improved.

  As the resin constituting the primer layer 3, polyester resin, polyvinyl pyrrolidone resin, polyvinyl alcohol resin, hydroxyethyl cellulose, polyacrylate resin, polyvinyl acetate resin, polyurethane resin, styrene acrylate resin, polyacrylamide resin Examples thereof include resins, polyamide resins, polyether resins, polystyrene resins, polyethylene resins, polypropylene resins, polyvinyl chloride resins, polyvinyl acetal resins such as polyvinyl acetoacetal and polyvinyl butyral, and the like.

  Moreover, the primer layer 3 can also be comprised from a colloidal inorganic pigment ultrafine particle. This not only prevents abnormal transfer of the yellow dye layer 2Y to the thermal transfer image receiving sheet during thermal transfer, but also prevents migration of the dye from the yellow dye layer 2Y to the primer layer 3 during printing, thereby accepting the thermal transfer image receiving sheet. Dye diffusion to the layer side can be performed effectively, and the print density can be increased.

  As the colloidal inorganic pigment ultrafine particles, conventionally known compounds can be used. For example, silica (colloidal silica), alumina or alumina hydrate (alumina sol, colloidal alumina, cationic aluminum oxide or its hydrate, suspect boehmite, etc.), aluminum silicate, magnesium silicate, magnesium carbonate, magnesium oxide, oxidation Examples include titanium. In particular, colloidal silica and alumina sol are preferably used. These colloidal inorganic pigment ultrafine particles have a primary average particle size of 100 nm or less, preferably 50 nm or less.

Primer layer 3 uses a gravure coating method, a roll coating method, a screen printing method, and a gravure plate as a primer layer coating solution prepared by dissolving or dispersing colloidal inorganic pigment ultrafine particles in an appropriate solvent. It can be formed by coating and drying by a conventionally known forming means such as a reverse roll coating method. The coating amount of the coating solution for a primer layer is preferably 0.02g / m ² ~1.0g / m ² approximately.

  Various functional layers may be provided together with or in place of the primer layer 3. Examples of the various functional layers include an antistatic layer.

(Back layer)
As shown in FIG. 1, a back layer 5 is provided on the other surface of the substrate 1 for improving heat resistance and running performance of the thermal head during printing.

  The back layer 5 can be formed by appropriately selecting a conventionally known thermoplastic resin or the like. As such a thermoplastic resin, for example, polyester resins, polyacrylate resins, polyvinyl acetate resins, styrene acrylate resins, polyurethane resins, polyethylene resins, polypropylene resins, and other polyolefin resins, Polystyrene resin, polyvinyl chloride resin, polyether resin, polyamide resin, polyimide resin, polyamideimide resin, polycarbonate resin, polyacrylamide resin, polyvinyl chloride resin, polyvinyl butyral resin, polyvinyl acetoacetal resin, etc. Examples thereof include thermoplastic resins such as polyvinyl acetal resin, and silicone modified products thereof.

  Moreover, you may add a hardening | curing agent to above-described resin. As the polyisocyanate resin that functions as a curing agent, conventionally known ones can be used without any particular limitation. Among them, it is desirable to use an adduct of an aromatic isocyanate. As the aromatic polyisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, or a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, Examples include p-phenylene diisocyanate, trans-cyclohexane-1,4-diisocyanate, xylylene diisocyanate, triphenylmethane triisocyanate, and tris (isocyanatophenyl) thiophosphate, particularly 2,4-toluene diisocyanate and 2,6-toluene diisocyanate. Or, a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate is preferable. Such a polyisocyanate resin crosslinks the above-mentioned hydroxyl group-containing thermoplastic resin using the hydroxyl group, thereby improving the coating strength and heat resistance of the back layer.

  In addition to the above thermoplastic resin, the back layer 5 has a wax, a higher fatty acid amide, a phosphoric ester compound, a metal soap, a silicone oil, a surfactant and other release agents for the purpose of improving slip properties, fluorine It is preferable that various additives such as organic powders such as resin, inorganic particles such as silica, clay, talc, calcium carbonate and the like are contained, and it is particularly preferable that at least one kind of phosphate ester or metal soap is contained. preferable.

The back layer 5 is, for example, a surface of the substrate 1 opposite to the yellow dye layer 2Y obtained by dispersing or dissolving the thermoplastic resin and various additives added as necessary in a suitable solvent. Further, it can be formed by applying and drying by a known means such as a gravure printing method, a screen printing method, a reverse roll coating printing method using a gravure plate. The coating amount of the back layer 5, from the viewpoint of improvement of such as heat resistance, it is preferable that the coating amount after drying is 3 g / m ² or less, to 0.1g / m ² ~2g / m ² Is more preferable.

  Hereinafter, the present invention will be described with reference to examples and comparative examples. “Parts” in the text are based on mass unless otherwise noted. Moreover, the component contained in each coating liquid is solid content 100% unless there is particular notice.

Example 1
A polyethylene terephthalate film having a thickness of 5 μm was used as a substrate, and a back layer coating solution having the following composition was applied thereon so as to be 1.0 g / m ² when dried to form a back layer.
Next, a primer layer coating solution having the following composition was applied to the surface of the substrate opposite to the side on which the back layer was provided, so that the primer layer was 0.10 g / m ² when dried to form a primer layer. Next, a yellow dye layer was formed by applying a yellow dye layer coating solution 1 having the following composition on the primer layer so as to be 0.35 g / m ² when dried, and drying at 80 ° C. for 2 minutes. 1 thermal transfer sheet was obtained.

<Back layer coating liquid>
-Polyvinyl butyral resin 6.0 parts (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.)
-Polyisocyanate curing agent 22.0 parts (Bernock D750-45, solid content 45%, manufactured by DIC Corporation)
・ Phosphate ester 3.0 parts (Pricesurf A-208N, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
・ Talc 1.0 part (Microace P-3, manufactured by Nippon Talc Industry Co., Ltd.)
・ Methyl ethyl ketone 60.0 parts ・ Toluene 60.0 parts

<Primer layer coating solution>
・ Alumina sol (solid content 10%) 50 parts (Alumina sol 200 (feather shape), manufactured by Nissan Chemical Industries, Ltd.)
・ 5 parts of polyvinylpyrrolidone resin (K-90 ISP) ・ 25 parts of water ・ 20 parts of isopropyl alcohol

<Yellow dye layer coating solution 1 (D / B ratio = 2.5)>
-Compound represented by the above general formula (1) 1.375 parts-Solvent Yellow 93 1.125 parts-Nitrocellulose resin (solid content 70% H40 equivalent) 1.43 parts (solid content 1.0 part)
(DHM10-25 manufactured by Inabata Sangyo Co., Ltd.)
A solvent (toluene / MEK = 1: 1) was added to make 100 parts.

(Example 2)
A thermal transfer sheet of Example 2 was obtained in the same manner as in Example 1 except that the yellow dye layer coating liquid 2 having the following composition was used instead of the yellow dye layer coating liquid 1.

<Yellow dye layer coating solution 2 (D / B ratio = 2.5)>
-Compound represented by the above general formula (1) 1.500 parts-Solvent Yellow 93 1.000 parts-Nitrocellulose resin (solid content 70% H40 equivalent) 1.43 parts (solid content 1.0 part)
(DHM10-25 manufactured by Inabata Sangyo Co., Ltd.)
A solvent (toluene / MEK = 1: 1) was added to make 100 parts.

(Example 3)
A thermal transfer sheet of Example 3 was obtained in the same manner as in Example 1 except that the yellow dye layer coating liquid 3 having the following composition was used instead of the yellow dye layer coating liquid 1.

<Yellow Dye Layer Coating Liquid 3 (D / B Ratio = 2.5)>
-Compound represented by the above general formula (1) 1.625 parts-Solvent Yellow 93 0.875 parts-Nitrocellulose resin (solid content 70% H40 equivalent) 1.43 parts (solid content 1.0 part)
(DHM10-25 manufactured by Inabata Sangyo Co., Ltd.)
A solvent (toluene / MEK = 1: 1) was added to make 100 parts.

Example 4
A thermal transfer sheet of Example 4 was obtained in the same manner as in Example 1 except that the yellow dye layer coating liquid 4 having the following composition was used instead of the yellow dye layer coating liquid 1.

<Yellow dye layer coating solution 4 (D / B ratio = 2.5)>
-Compound shown by the above general formula (1) 1.138 parts-Solvent Yellow 93 0.612 parts-Compound shown by the above general formula (2-1) 0.375 parts-In the above general formula (3-1) 0.375 parts of the indicated compound / nitrocellulose resin (solid content 70% equivalent to H40) 1.43 parts (solid content 1.0 part)
(DHM10-25 manufactured by Inabata Sangyo Co., Ltd.)
A solvent (toluene / MEK = 1: 1) was added to make 100 parts.

(Example 5)
A thermal transfer sheet of Example 5 was obtained in the same manner as in Example 1 except that the yellow dye layer coating liquid 5 having the following composition was used in place of the yellow dye layer coating liquid 1.

<Yellow dye layer coating solution 5 (D / B ratio = 2.5)>
-Compound shown by the said General formula (1) 1.138 parts-Solvent Yellow 93 0.612 parts-Compound shown by the said General formula (2-1) 0.750 part-Nitrocellulose resin (solid content 70% H40 Equivalent) 1.43 parts (solid content 1.0 part)
(DHM10-25 manufactured by Inabata Sangyo Co., Ltd.)
A solvent (toluene / MEK = 1: 1) was added to make 100 parts.

(Example 6)
A thermal transfer sheet of Example 6 was obtained in the same manner as in Example 1 except that the yellow dye layer coating liquid 6 having the following composition was used instead of the yellow dye layer coating liquid 1.

<Yellow Dye Layer Coating Liquid 6 (D / B Ratio = 2.5)>
-Compound represented by the above general formula (1) 1.375 parts-Solvent Yellow 93 1.125 parts-Nitrocellulose resin (solid content 70% H40 equivalent) 1.0 part (solid content 0.7 parts)
(DHM10-25 manufactured by Inabata Sangyo Co., Ltd.)
・ Polyvinyl butyral resin 0.3 part (S-REC BX-L manufactured by Sekisui Chemical Co., Ltd.)
A solvent (toluene / MEK = 1: 1) was added to make 100 parts.

(Example 7)
A thermal transfer sheet of Example 7 was obtained in the same manner as in Example 1 except that the yellow dye layer coating liquid 7 having the following composition was used instead of the yellow dye layer coating liquid 1.

<Yellow dye layer coating solution 7 (D / B ratio = 2.5)>
-Compound represented by the above general formula (1) 1.690 parts-Solvent Yellow 93 0.810 parts-Nitrocellulose resin (solid content 70% H40 equivalent) 1.43 parts (solid content 1.0 part)
(DHM10-25 manufactured by Inabata Sangyo Co., Ltd.)
A solvent (toluene / MEK = 1: 1) was added to make 100 parts.

(Example 8)
A thermal transfer sheet of Example 8 was obtained in the same manner as in Example 1 except that the yellow dye layer coating liquid 8 having the following composition was used instead of the yellow dye layer coating liquid 1.

<Yellow dye layer coating solution 8 (D / B ratio = 2.5)>
-2.017 parts of the compound represented by the general formula (1)-0.483 parts of Solvent Yellow 93-nitrocellulose resin (solid content 70% H40 equivalent) 1.43 parts (solid content 1.0 part)
(DHM10-25 manufactured by Inabata Sangyo Co., Ltd.)
A solvent (toluene / MEK = 1: 1) was added to make 100 parts.

(Comparative Example 1)
A thermal transfer sheet of Comparative Example 1 was obtained in the same manner as in Example 1 except that the yellow dye layer coating liquid A having the following composition was used instead of the yellow dye layer coating liquid 1.

<Yellow dye layer coating liquid A (D / B ratio = 2.5)>
· Solvent Yellow 93 2.500 parts · Nitrocellulose resin (solid content 70% H40 equivalent) 1.43 parts (solid content 1.0 part)
(DHM10-25 manufactured by Inabata Sangyo Co., Ltd.)
A solvent (toluene / MEK = 1: 1) was added to make 100 parts.

(Comparative Example 2)
A thermal transfer sheet of Comparative Example 2 was obtained in the same manner as in Example 1 except that the yellow dye layer coating liquid B having the following composition was used instead of the yellow dye layer coating liquid 1.

<Yellow Dye Layer Coating Liquid B (D / B Ratio = 2.5)>
-Compound represented by the above general formula (1) 1.275 parts-Solvent Yellow 93 1.225 parts-Nitrocellulose resin (corresponding to solid content 70% H40) 1.43 parts (solid content 1.0 part)
(DHM10-25 manufactured by Inabata Sangyo Co., Ltd.)
A solvent (toluene / MEK = 1: 1) was added to make 100 parts.

(Comparative Example 3)
A thermal transfer sheet of Comparative Example 3 was obtained in the same manner as in Example 1 except that the yellow dye layer coating liquid C having the following composition was used instead of the yellow dye layer coating liquid 1.

<Yellow dye layer coating liquid C (D / B ratio = 2.5)>
-Compound shown by the above general formula (1) 2.500 parts-Nitrocellulose resin (solid content 70% H40 equivalent) 1.43 parts (solid content 1.0 part)
(DHM10-25 manufactured by Inabata Sangyo Co., Ltd.)
A solvent (toluene / MEK = 1: 1) was added to make 100 parts.

(Comparative Example 4)
A thermal transfer sheet of Comparative Example 3 was obtained in the same manner as in Example 1 except that the yellow dye layer coating liquid D having the following composition was used instead of the yellow dye layer coating liquid 1.

<Yellow Dye Layer Coating Liquid D (D / B Ratio = 2.5)>
-Compound represented by the above general formula (1) 1.375 parts-Solvent Yellow 93 1.125 parts-Polyvinyl acetal resin 1.0 part (ESREC KS-5 manufactured by Sekisui Chemical Co., Ltd.)
A solvent (toluene / MEK = 1: 1) was added to make 100 parts.

(Evaluation of print density)
Using the thermal transfer sheets of the Examples and Comparative Examples obtained above, using a printer for DS40 manufactured by DNP Photo Lucio with a test printer (head resistance value: 5058Ω, printing conditions: 25.5 V 2 ms, pulse duty ratio 85%) An image was formed by performing Max gradation printing on the thermal transfer image-receiving sheet of set DS40PC (DM4640). Next, the protective layer of the media set was transferred onto this image to form prints of Examples and Comparative Examples.

  The density of the printed matter of each Example and Comparative Example was measured under the following conditions, and the printing density was evaluated based on the following evaluation criteria. Table 1 shows the colorimetric values of density and the evaluation results.

(Concentration colorimetric conditions)
Colorimeter: Spectrometer SpectroLino (manufactured by Gretag Macbeth)
Concentration filter: ANSI Status A

"Evaluation criteria"
○ The concentration is 2.0 or more.
X: The concentration is less than 2.0.

(Evaluation of dye transfer efficiency)
The thermal transfer sheets of each Example and Comparative Example after Max gradation printing, and the thermal transfer sheets of each Example and Comparative Example that have not been printed are cut into a size of 5 cm × 5 cm, and then cut into a size of 5 cm × 5 cm. Then, using high performance liquid chromatography (manufactured by Shimadzu Corporation), the amount of dye in the printed part and the unprinted part was measured. At this time, the difference between the amount of dye in the unprinted portion and the amount of remaining dye in the printed portion is defined as the amount of transferred dye transferred to the thermal transfer image-receiving sheet, and the value obtained by dividing the amount of transferred dye by the amount of dye in the unprinted portion is defined as the dye transfer efficiency. did. Table 1 shows the evaluation results of the dye transfer efficiency according to the following evaluation criteria together with the actually measured value of the dye transfer efficiency.

"Evaluation criteria"
A: The dye transfer efficiency is 80% or more.
X: Dye transfer efficiency is less than 80%.

(Kick evaluation)
The dye layer of the thermal transfer sheet of each Example and Comparative Example and the heat-resistant slip layer of the thermal transfer image-receiving sheet used in the above density evaluation were overlapped and applied with a load of 1.5 kg / cm ² at 40 ° C. The sample was stored for 96 hours in a 90% humidity environment, and the degree of dye transfer (kick) of the dye layer to the heat-resistant slipping layer side was confirmed. The degree of dye transfer was measured using a color difference meter (CR321 manufactured by Konica Minolta Co., Ltd.) by measuring the hue of the heat-resistant slipping layer in the transfer portion and the hue of the heat-resistant slipping layer in the non-transferred portion. ^* ) Was calculated by the following formula.

ΔE ^* = ((difference in L ^* value before and after load) ² + (difference in a ^* value before and after load) ² + (difference in b ^* value before and after load) ² ) ^1/2

  Table 1 shows the calculation result of the color difference, and also shows the evaluation result of the storage stability evaluated according to the following evaluation criteria. In addition, it shows that the degree of a kick is so small that the color difference before and behind a load is small.

"Evaluation criteria"
A: The color difference (ΔE ^* ) of the heat resistant slipping layer before and after the load is less than 8.
Δ: The color difference (ΔE ^* ) of the heat-resistant slip layer before and after the load is 8 or more and less than 10.
X: The color difference (ΔE ^* ) of the heat-resistant slipping layer before and after the load is 10 or more.

(Earth dirt evaluation)
The heat transfer sheet of each Example and Comparative Example was overlaid with the dye layer of the heat transfer image-receiving sheet used in the dye transfer efficiency evaluation to face each other, and a load of 27 Kg / cm ² was applied at 40 ° C. The sample was stored for 96 hours in a 90% humidity environment. The thermal transfer sheets of each Example and Comparative Example after storage were printed using a test printer that was used with the above dye transfer efficiency to obtain a print using the thermal transfer sheet after storage. The hue of the print using the thermal transfer sheet after storage and the color of the print using the non-storage thermal transfer sheet are measured using Spectrolino (manufactured by X-Light), and the color difference (ΔE ^* ) is expressed by the following equation. Calculated.

ΔE ^* = ((difference between L ^* values before and after storage) 2+ (difference between a ^* values before and after storage) ² + (difference between b ^* values before and after storage) ² ) ^1/2

  Table 1 shows the calculation result of the color difference, and also shows the evaluation result of the storage stability evaluated according to the following evaluation criteria. In addition, it shows that the smaller the color difference before and after storage, the less dye precipitation in a high temperature / high humidity environment, and the higher the storage stability.

"Evaluation criteria"
A: The color difference (ΔE ^* ) of the printed material before and after storage is less than 1.0.
Δ: The color difference (ΔE ^* ) of the printed material before and after storage is 1.0 or more and less than 2.0.
X: The color difference (ΔE ^* ) of the printed material before and after storage is 2.0 or more.

  As is clear from Table 1, according to the thermal transfer sheets of Examples 1 to 8 that satisfy all of the invention-specific matters of the present invention, good evaluation could be obtained in all evaluation items. On the other hand, in the thermal transfer sheets of Comparative Examples 1 to 4 that do not satisfy even one of the invention-specific matters of the present invention, at least one evaluation was inferior to the examples. This also revealed the superiority of the present invention.

DESCRIPTION OF SYMBOLS 10 ... Thermal transfer sheet 1 ... Base material 2Y ... Yellow dye layer 2M ... Magenta dye layer 2C ... Cyan dye layer 3 ... Primer layer 5 ... Back layer

Claims (5)

A thermal transfer sheet provided with a yellow dye layer on one side of a substrate and a back layer on the other side of the substrate,
The yellow dye layer contains a binder resin and a sublimable dye,
The binder resin includes nitrocellulose,
The sublimable dye includes a sublimable dye represented by the following general formula (1) and Solvent Yellow 93,
The yellow dye layer contains 55% by weight to 85% by weight of the sublimable dye represented by the following general formula (1) with respect to the total mass of the sublimable dye represented by the following general formula (1) and Solvent Yellow 93. A thermal transfer sheet comprising:

The yellow dye layer further contains one or both of sublimable dyes represented by the following general formula (2) and the following general formula (3): Item 2. The thermal transfer sheet according to Item 1.

(R1 in the general formula (2) represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group, and R2 represents a hydrogen atom, a halogen atom, an optionally substituted alkoxy group, or optionally substituted. An alkylthio group or an optionally substituted arylthio group, wherein R3 represents a substituted or unsubstituted alkoxycarbonyl group, a substituted or unsubstituted alkylaminocarbonyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryloxy group; Represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a heterocyclic group or a halogen atom.)

(R1 in the general formula (3) represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted allyl group, or a substituted or unsubstituted aralkyl group, and R2 represents a substituted or unsubstituted aralkyl group. Unsubstituted alkyl group, substituted or unsubstituted aralkyloxycarbonyl group, substituted or unsubstituted alkoxycarbonyl group, substituted or unsubstituted alkylaminocarbonyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alkylamino Represents a sulfonyl group, a substituted or unsubstituted cycloalkyl group, a cyano group, a nitro group or a halogen atom.)   The total solid content of the sublimable dyes represented by the general formula (2) and the general formula (3) with respect to the total solid content of all sublimable dyes contained in the yellow dye layer is 33% by mass or less. The thermal transfer sheet according to claim 2. The sublimable dye represented by the general formula (2) is a sublimable dye represented by the following general formula (2-1),
The sublimable dye represented by the general formula (3) is a sublimable dye represented by the following general formula (3-1) and / or the following general formula (3-2): 3. The thermal transfer sheet according to 3.

  2. The mass ratio (D / B ratio (sublimation dye / binder resin)) of the sublimable dye and the binder resin in the yellow dye layer is 2.0 or more and 3.5 or less. 5. The thermal transfer sheet according to any one of items 4 to 4.

Images