JP5760763B2 - Thermal transfer sheet - Google Patents

Description

  The present invention relates to a thermal transfer sheet, and more particularly to a thermal transfer sheet in which there is no possibility that the color development characteristics of a dye layer differ depending on the presence or absence of overlapping with a detection layer.

  Conventionally, various thermal transfer recording methods are known, and among them, a sublimation transfer method is attracting attention. This is considered to be due to the fact that a dye is used as a coloring material, which is clear and excellent in transparency, and that a high-quality full-color image excellent in reproducibility and gradation of intermediate colors can be formed.

  In the sublimation transfer method, a thermal transfer sheet (sublimation thermal transfer sheet) in which a dye layer in which a sublimable dye is supported on an appropriate binder is formed on a substrate such as a polyester film is used. From here, the sublimation dye is thermally transferred onto a transfer material that can be dyed with a sublimation dye, such as paper or a plastic film, and a dye-receiving layer is formed, thereby forming various full-color images. A member such as a thermal head is used for heating, and a large number of color dots whose heating amount is controlled are formed. The image formed in this way is of high quality comparable to offset printing or gravure printing.

  As such a sublimation heat transfer sheet, for example, as shown in Patent Document 1, three colors of a yellow dye layer, a magenta dye layer, a cyan dye layer, or a four-color dye layer including a black dye layer are repeatedly applied in a surface sequential manner. What has been proposed. Detection marks are formed between the dye layers of three colors or four colors. The detection mark is printed by ink using a pigment such as carbon black or aluminum. Using such a sublimation heat transfer sheet, a yellow image, a magenta image, a cyan image, and, if necessary, a black image are superimposed and transferred onto the image receiving sheet to form a color image. At that time, the detection mark of the sublimation heat transfer sheet is read, and based on this, the print start position of the sublimation heat transfer sheet is determined.

  However, in the conventional thermal transfer sheet, it is necessary to provide an extra region for forming a detection mark between the dye layers. This is because if the area where the detection mark is formed is heated with a thermal head, the detection mark itself may be thermally transferred, and an image that should originally be formed may not be formed.

  As a thermal transfer sheet that solves the above problems, for example, Patent Document 2 proposes a sheet including a base material including a dye region capable of thermal transfer. The dye region has a printable region having a first optical density and a printable region having a second optical density, and these optical densities are different. The optical density difference can be detected by an optical sensor or the like.

  However, in Patent Document 2, regions having different optical densities are formed by providing a difference in the coating amount of the dye layer. Therefore, there is a possibility that the color development characteristics may be different between the printable area having the first optical density and the printable area having the second optical density. That is, in the thermal transfer sheet of Patent Document 2, it is difficult to use the printable area having the first optical density and the printable area having the second optical density as areas having equivalent color development characteristics. . As described above, sufficient research has not been made so far regarding thermal transfer sheets in which there is no possibility that the coloring characteristics of the dye layer differ depending on the presence or absence of overlapping with the detection layer.

JP 2009-83161 A Special table 2009-541101

  The present invention has been made in view of the above-described background art, and its purpose is that the detection layer is formed so as to overlap with the dye layer, and there is a possibility that the coloring characteristics of the dye layer may differ depending on the presence or absence of overlap with the detection layer. There is no need to provide a thermal transfer sheet.

That is, according to one aspect of the present invention, a thermal transfer in which a back surface layer is formed on one surface of the base material and the base material, and at least one color material layer is formed on the other surface of the base material. In the sheet, a detection layer is formed between the base material and the back layer and / or between the base material and the color material layer so as to overlap the color material layer, and the detection layer has the following formula (2 A thermal transfer sheet comprising a fluorescent dye that is a rare earth complex synthesized by the reaction formula shown in FIG.

  According to the present invention, it is possible to provide a thermal transfer sheet in which there is no possibility that the color development characteristics of the dye layer differ depending on the presence or absence of overlap with the detection layer. Thereby, the area where the detection layer is formed can be used for printing.

It is a schematic cross section which shows an example of the thermal transfer sheet by this invention. It is a schematic cross section which shows an example of the thermal transfer sheet by this invention. It is a schematic cross section which shows an example of the thermal transfer sheet by this invention. It is a schematic cross section which shows an example of the thermal transfer sheet by this invention.

Thermal transfer sheet In the thermal transfer sheet of the present invention, a back layer is formed on one surface of the base material and the base material, and a dye layer is formed on the other surface of the base material, between the base material and the back layer. And / or a detection layer is formed between the substrate and the dye layer so as to overlap the dye layer.

  According to one embodiment of the present invention, a back surface layer is formed on one surface of the base material and the base material, a dye layer is formed on the other surface of the base material, and the base material and the dye layer A detection layer is formed between them. Specifically, FIG. 1 shows a schematic sectional view of an example of the thermal transfer sheet according to the present invention. A thermal transfer double-sided image receiving sheet 10 shown in FIG. 1 has a base material 11, a back layer 12 formed on one surface of the base material 11, and a dye layer 13 and a detection layer 14 formed on the other surface of the base material. It will be.

  According to another aspect of the present invention, a base material, a back layer is formed on one surface of the base material, a dye layer is formed on the other surface of the base material, the base material and the dye layer, A detection layer is formed between the two. Specifically, FIG. 2 shows a schematic sectional view of an example of the thermal transfer sheet according to the present invention. The thermal transfer double-sided image receiving sheet 20 shown in FIG. 2 has a base material 21, a back layer 22 formed on one surface of the base material 21, and a dye layer 23 and a detection layer 24 formed on the other surface of the base material. It will be. 1 is different from FIG. 1 in that a plurality of dye layers are formed.

  According to another aspect of the present invention, a back surface layer is formed on one surface of the base material and the base material, a dye layer is formed on the other surface of the base material, the base material and the back surface layer, A detection layer is formed between the two. Specifically, FIG. 3 shows a schematic sectional view of an example of the thermal transfer sheet according to the present invention. The thermal transfer double-sided image receiving sheet 30 shown in FIG. 3 has a base material 31, a back layer 32 on one surface of the base material 31, and a dye layer 33 and a detection layer 34 on the other surface of the base material. It will be. 1 and 2 differ in that the detection layer is formed on the surface of the base sheet on which the back layer is formed.

  According to another aspect of the present invention, a back surface layer is formed on one surface of the base material and the base material, and a dye layer is formed on the other surface of the base material. And a detection layer is formed between the substrate and the dye layer. Specifically, FIG. 4 shows a schematic cross-sectional view of an example of the thermal transfer sheet according to the present invention. The thermal transfer double-sided image receiving sheet 40 shown in FIG. 4 has a base material 41, a back layer 42 formed on one surface of the base material 41, and a dye layer 43 and a detection layer 44 formed on the other surface of the base material. It will be. It differs from FIGS. 1-3 in the point by which the detection layer is formed in both surfaces of a base material sheet.

Substrate The substrate in the present invention has a function of holding a dye layer and the like. Further, since heat is applied during thermal transfer, it is preferable that the material has a mechanical strength that does not hinder handling even when heated. As such a base material, any material having a conventionally known level of heat resistance and strength can be used. The material of the substrate is, for example, polyethylene terephthalate film, 1,4-polycyclohexylenedimethylene terephthalate film, polyethylene naphthalate film, polyphenylene sulfide film, polystyrene film, polypropylene film, polysulfone film, aramid film, polycarbonate film, polyvinyl alcohol. Resin films such as films, cellophane, cellulose derivatives such as cellulose acetate, polyethylene films, polyvinyl chloride films, nylon films, polyimide films, and ionomer films can be used. The base material having a thickness of about 0.5 to 50 μm, preferably about 3 to 10 μm can be used.

The back layer heat resistant slipping layer has a function of improving the running performance, heat resistance, etc. of the thermal head during printing. Such a back layer preferably contains a resin and a lubricant, and may further contain a curing agent and other additives.
(resin)
The resin contained in the back layer has heat resistance and has a function of retaining a lubricant and other additives. Examples of such resins include polyester resins, polyacrylate resins, polyvinyl acetate resins, styrene acrylate resins, polyurethane resins, polyolefin resins, polystyrene resins, polyvinyl chloride resins, and polyethers. Resin, polyamide resin, polyimide resin, polyamideimide resin, polycarbonate resin, polyethylene resin, polypropylene resin, polyacrylate resin, polyacrylamide resin, polyvinyl chloride resin, polyvinyl butyral resin, polyvinyl acetoacetal resin, etc. Can be used.
(Lubricant)
The lubricant contained in the back layer has a function of improving the lubricity with the thermal head. As such a material, for example, polyethylene wax, silicone oil, higher fatty acid amide, phosphate ester, polyvalent metal salt of alkyl phosphate ester, metal salt of alkyl carboxylic acid, and the like can be used. As the polyvalent metal salt of alkyl phosphate ester or the metal salt of alkyl carboxylic acid, zinc stearyl phosphate or zinc stearate can be suitably used. Polyethylene waxes include high-density and low-density polyethylene waxes, and low-density polyethylene includes many ethylene polymers that are branched due to the structure, whereas high-density polyethylene is relatively polyethylene. It is mainly composed of a straight chain structure. For example, polyethylene wax particles having a density of 0.94 to 0.97 (polyethylene wax finely powdered) can be suitably used.
(Curing agent)
The curing agent contained in the back layer reacts with the resin and the lubricant, and thereby has a function of further increasing the heat resistance of the back layer. As such a hardening | curing agent, a conventionally well-known thing can be used without a restriction | limiting in particular, For example, a polyisocyanate resin can be used conveniently. Among them, it is desirable to use an adduct of aromatic isocyanate. Examples of such aromatic polyisocyanates include 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, Examples include trisidine diisocyanate, p-phenylene diisocyanate, trans-cyclohexane-1,4-diisocyanate, xylylene diisocyanate, triphenylmethane triisocyanate, and tris (isocyanatophenyl) thiophosphate. Particularly, 2,4-toluene diisocyanate, 2,6 -Toluene diisocyanate or a mixture of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate is preferred.

  In addition to the above-described components, inorganic or organic fine particles may be added to the back layer of the present invention for auxiliary adjustment of lubricity. Examples of the inorganic fine particles include clay minerals such as talc and kaolin, carbonates such as calcium carbonate and magnesium carbonate, hydroxides such as aluminum hydroxide and magnesium hydroxide, sulfates such as calcium sulfate, and oxides such as silica. Inorganic fine particles such as graphite, nitrate and boron nitride. Organic fine particles include acrylic resin, Teflon (registered trademark) resin, silicone resin, lauroyl resin, phenol resin, acetal resin, polystyrene resin, nylon resin, etc., or crosslinked resin obtained by reacting these with a crosslinking agent. Examples thereof include fine particles. Of the above-described inorganic or organic fine particles, talc can be suitably used. Moreover, you may use what is marketed, for example, microace P-3 (made by Nippon Talc Kogyo Co., Ltd.) etc. can be used conveniently.

  For the back layer, the above components are dissolved in an appropriate solvent such as acetone, methyl ethyl ketone, toluene, xylene, etc., and used as a back layer forming ink, which is then used in conventional appropriate printing such as gravure coater, roll coater, wire bar, etc It can form by apply | coating on the base material mentioned above by the method, and drying.

The back layer has a thickness of 0.05 to 5 μm, preferably 0.1 to 1 μm. If the film thickness is less than 0.05 μm, the effect as the back layer is not sufficient, and if it is more than 1 μm, heat transfer from the thermal head to the heat transferable color material layer is deteriorated, and the print density is low. The disadvantage of becoming.

Color material layer The color material layer has a function of transferring dye to the receiving layer in accordance with the amount of heating from the thermal head. In the present invention, a color material layer of only one color may be formed on the substrate, or a dye layer of two or more colors may be repeatedly formed in the surface order. The color material layer of the present invention contains a resin and a dye, and may further contain other additives.
(resin)
The resin contained in the color material layer has a function of retaining a dye and other additives, and generally has heat resistance and can have a proper affinity with the dye. Examples of such resins include cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, and cellulose butyrate; polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetoacetal, polyvinyl Examples thereof include vinyl resins such as pyrrolidone; acrylic resins such as poly (meth) acrylate and poly (meth) acrylamide; polyurethane resins; polyamide resins; polyester resins; Among the above-described resins, from the viewpoint of excellent heat resistance, dye transferability, and the like, cellulose resins, vinyl resins, acrylic resins, urethane resins, polyester resins, and the like are preferable, vinyl resins are more preferable, Polyvinyl butyral, polyvinyl acetoacetal and the like are particularly preferable.

(dye)
The sublimation dye used in the color material layer is not particularly limited, and conventionally known dyes can be used. Such as, for example, diarylmethane dyes; triarylmethane dyes; thiazole dyes; merocyanine dyes; pyrazolone dyes; methine dyes; indoaniline dyes; Azomethine dyes such as azomethine and pyridone azomethine; xanthene dyes; oxazine dyes; cyanostyrene dyes such as dicyanostyrene and tricyanostyrene; thiazine dyes; azine dyes; acridine dyes; benzeneazo dyes; Azo dyes such as azo, isothiazole azo, pyrrole azo, pyrazole azo, imidazole azo, thiadiazole azo, triazole azo, disazo; spiropyran dyes; indolinospiropyran Fluorane dyes, rhodamine lactam dyes, naphthoquinone dyes, anthraquinone dyes, quinophthalone dyes, and the like, and more specifically, compounds exemplified in JP-A-7-149062 It is done.

The color material layer may use additives such as a release agent, inorganic fine particles, and organic fine particles as desired. Examples of the mold release agent include silicone oil and phosphate ester. Inorganic fine particles include carbon black, aluminum, molybdenum disulfide and the like. Examples of the organic fine particles include polyethylene wax.

  The above-described color material layer is prepared by dissolving or dispersing the above-described dye and binder resin in an appropriate organic solvent or water together with additives to be added as necessary, and further, a gravure printing method It can be formed by applying the coating liquid on one surface of the substrate and drying it by a known means such as a screen printing method or a reverse roll coating printing method using a gravure plate.

  Examples of the organic solvent include toluene, methyl ethyl ketone, ethanol, isopropyl alcohol, cyclohexanone, dimethylformamide [DMF] and the like. The coating amount of the dye layer is about 0.2 to 6.0 g / m2, preferably about 0.2 to 3.0 g / m2 on a dry solid basis.

(Detection layer)
The detection layer has a function that can be identified by detection means such as an optical sensor. The detection layer of the present invention is formed by overlapping the dye layer between the base material and the color material layer and / or the base material and the back layer. Moreover, the detection layer of the present invention has a binder resin and a fluorescent dye, and may further contain other additives. Thereby, it is possible to provide a thermal transfer sheet in which there is no possibility that the color development characteristics of the dye layer differ depending on the presence or absence of overlapping with the detection layer. As a result, since the region where the detection layer is formed can also be used for thermal transfer, the region that cannot be used for printing can be reduced.

(resin)
The binder resin contained in the detection layer has a function of holding a fluorescent dye and other additives, and generally, a binder resin having an appropriate affinity with the fluorescent dye can be used. As such, for example, cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose butyrate; polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetoacetal, polyvinyl pyrrolidone Vinyl resins such as poly (meth) acrylates, poly (meth) acrylamides and the like; polyurethane resins; polyamide resins; polyester resins; fluorine resins, and the like.

(Fluorescent dye)
The fluorescent dye contained in the detection layer has a function that can be detected by an optical sensor. A conventionally known fluorescent dye can be used without particular limitation as long as it has such a function, but it is preferably substantially transparent to visible light, and preferably has a high emission intensity. By being substantially transparent to visible light, the formed part of the detection layer cannot be discriminated visually. As a result, the region where the detection layer and the dye layer overlap cannot be visually identified. When the user visually observes the thermal transfer sheet, if there is density unevenness due to the detection layer, there is a possibility that a difference in color development characteristics occurs. If the detection layer uses a fluorescent dye substantially transparent to visible light, such anxiety does not occur.

  As such a fluorescent dye, for example, a rare earth complex having a compound represented by the following formula (1) as a ligand can be used. Moreover, the compound described in Unexamined-Japanese-Patent No. 2006-77191 can be used conveniently.

一般的に色材層に含まれる染料の中には、蛍光を発するものもある。したがって、検知層に含まれる蛍光染料の発光強度が弱い場合は、染料が発する蛍光と識別できない虞がある。上述した発光強度が強い蛍光染料を使用した検知層であれば、染料が蛍光を発する場合であっても、これと識別できる強い蛍光を発することができる。これによって、検知層を確実に光学センサで検知することができる。

In general, some dyes contained in the color material layer emit fluorescence. Therefore, when the emission intensity of the fluorescent dye contained in the detection layer is weak, there is a possibility that it cannot be distinguished from the fluorescence emitted by the dye. If it is a detection layer using the fluorescent dye with strong luminescence intensity mentioned above, even if it is a case where a dye emits fluorescence, it can emit strong fluorescence which can be distinguished from this. Thereby, the detection layer can be reliably detected by the optical sensor.

  The above-described detection layer may use additives such as a surfactant, a dispersant, and an antifoaming agent as desired.

  The above-described detection layer is prepared by dissolving or dispersing the above-described fluorescent dye and binder resin in an appropriate organic solvent or water together with an additive that is added as necessary, and further, a gravure printing method It can be formed by applying the coating liquid on one surface of the substrate and drying it by a known means such as a screen printing method or a reverse roll coating printing method using a gravure plate.

  Examples of the organic solvent include toluene, methyl ethyl ketone, ethanol, isopropyl alcohol, cyclohexanone, dimethylformamide [DMF] and the like. The coating amount of the detection layer is 0.2 to 3.0 g / m 2, preferably about 0.5 to 2.0 g / m 2 on a dry solid basis.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not construed as being limited to the contents of the following examples.
Example 1
The back layer was formed by applying 1.0 g / m 2 (in terms of solid content) of the following back layer coating solution 1 to one surface of the substrate using a gravure coater and drying. As the substrate, a polyethylene terephthalate film having a thickness of 6 μm was used.
<Back layer coating liquid 1>
・ 4.55 parts of polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.)
Polyisocyanate 21.0 parts (Bernock D750-45, solid content 45% by mass, manufactured by Dainippon Ink & Chemicals, Inc.)
・ 3.0 parts of phosphate ester surfactant (Pricesurf A208N, manufactured by Daiichi Pharmaceutical Co., Ltd.)
・ Talc (Microace P-3, manufactured by Nippon Talc Kogyo Co., Ltd.) 0.7 parts ・ Methyl ethyl ketone 100.0 parts ・ Toluene 100.0 parts On the other side of the base material on which the back layer is formed, The detection layer coating solution 1 prepared as described above was applied and dried by a gravure coater so as to be 0.5 g / m @ 2 (in terms of solid content) to form a detection layer.
<Adjustment of detection layer coating solution 1>
First, a rare earth complex was synthesized according to the reaction formula shown below. That is, two types of phosphine oxides, triphenylphosphine oxide and trioctylphosphine oxide, were allowed to act on the rare earth metal compound as a ligand to obtain a rare earth complex. This rare earth complex is dissolved in Vertrel XF (trade name: manufactured by DuPont), which is a fluorine-based solvent, and further, 2% by weight of a pellet of fluorine-based polymer (trade name: Dinion THV, manufactured by Sumitomo 3M Co., Ltd.) is dissolved therein. Thus, the detection layer coating liquid 1 was obtained.

検知層を形成した基材上に、下記の色材層塗工液１を、１．０ｇ／ｍ2（固形分換算）塗工し、乾燥することによって色材層を形成した。これによって、図１に記載の層構成を有する熱転写シートを得た。
＜色材層用塗工液１＞
・分散染料（ホロンブリリアントイエロー−Ｓ−６ＧＬ） ５．５部
・ポリビニルアセトアセタール樹脂（エスレックＫＳ−５、積水化学工業（株）製）
４．５部
・メチルエチルケトン ４５．０部
・トルエン ４５．０部
（実施例２）
検知層を、基材と背面層の間に形成した以外は、実施例１と同様にして熱転写シートを得た。得られた熱転写シートは、図３の層構成を有するものであった。
（実施例３）
検知層を、基材と色材層の間、及び基材と背面層の間に形成した以外は、実施例１と同様にして熱転写シートを得た。得られた熱転写シートは、図４の層構成を有するものであった。
＜＜検知適正評価＞＞
実施例１〜３の熱転写シートに、ブラックライト及び中心波長４１０ｎｍのＬＥＤを照射し、以下の基準で検知層に相当する蛍光を確認した。評価結果を表１に併せて示す。

On the base material on which the detection layer was formed, the following color material layer coating solution 1 was applied at 1.0 g / m @ 2 (in terms of solid content) and dried to form a color material layer. Thus, a thermal transfer sheet having the layer configuration shown in FIG. 1 was obtained.
<Coloring material layer coating solution 1>
・ Disperse dye (holon brilliant yellow-S-6GL) 5.5 parts ・ Polyvinylacetoacetal resin (S-REC KS-5, manufactured by Sekisui Chemical Co., Ltd.)
4.5 partsMethyl ethyl ketone 45.0 partsToluene 45.0 parts (Example 2)
A thermal transfer sheet was obtained in the same manner as in Example 1 except that the detection layer was formed between the base material and the back layer. The obtained thermal transfer sheet had the layer configuration of FIG.
(Example 3)
A thermal transfer sheet was obtained in the same manner as in Example 1 except that the detection layer was formed between the base material and the color material layer and between the base material and the back layer. The obtained thermal transfer sheet had the layer structure of FIG.
<< Detection appropriateness evaluation >>
The thermal transfer sheets of Examples 1 to 3 were irradiated with black light and an LED having a center wavelength of 410 nm, and fluorescence corresponding to the detection layer was confirmed based on the following criteria. The evaluation results are also shown in Table 1.

<Evaluation criteria>
○: The fluorescence emission of the detection layer was confirmed visually.
X: Fluorescence emission of the detection layer could not be confirmed visually.
<< Visibility evaluation >>
The thermal transfer sheets of Examples 1 to 3 were visually confirmed and evaluated according to the following criteria. The evaluation results are also shown in Table 1.

<Evaluation criteria>
○ The detection layer is not visible.
X: The detection layer is visible.
<< Coloring characteristics evaluation >>
Sublimation type thermal transfer printer (manufactured by ALTECH ADS, model: MEGAPICEL III
), An image having an RGB value of 128 gradations was printed using the thermal transfer sheets of Examples 1 to 3. As the thermal transfer image receiving sheet, a dedicated thermal transfer image receiving sheet of MEGAPICEL III was used. The obtained image was visually evaluated according to the following criteria. The evaluation results are also shown in Table 1.

<Evaluation criteria>
○: There is no density unevenness corresponding to the detection layer.
X: There is density unevenness corresponding to the detection layer.

表１からも明らかな通り、本発明によって、検知層との重なりの有無によって色材層の発色特性が異なる虞がない熱転写シートを提供することができる。

As is clear from Table 1, according to the present invention, it is possible to provide a thermal transfer sheet in which the coloring property of the color material layer does not vary depending on whether it overlaps with the detection layer.

DESCRIPTION OF SYMBOLS 10 Thermal transfer sheet 11 Base material 12 Back layer 13 Dye layer 14 Detection layer 20 Thermal transfer sheet 21 Base material 22 Back layer 23 Dye layer 24 Detection layer 30 Thermal transfer sheet 31 Base material 32 Back layer 33 Dye Layer 34 Detection layer

Claims (1)

In a thermal transfer sheet in which a back surface layer is formed on one surface of the base material and the base material, and a color material layer of at least one color is formed on the other surface of the base material,
Between the base material and the back layer and / or between the base material and the color material layer, a detection layer is formed so as to overlap the color material layer,
The detection layer comprises a fluorescent dye that is a rare earth complex synthesized by the reaction formula shown in the following formula (2) .
A thermal transfer sheet characterized by that .

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