JP6657697B2 - Thermal transfer sheet - Google Patents

Description

  The present invention relates to a thermal transfer sheet in which a release layer, an intermediate layer, and a coloring layer are sequentially provided on at least a part of one surface of a base sheet.

  Conventionally, using a thermal transfer sheet in which a colorant such as a pigment or a dye is dispersed in a binder such as a heat-meltable wax or resin, and a heat-meltable colored ink layer is supported on a base sheet such as a plastic film. 2. Description of the Related Art There is known a melt transfer method in which energy corresponding to image information is applied by a heating device such as a head, and a colorant is transferred together with a binder onto an image receiving sheet such as paper or a plastic sheet. A printed image formed by this fusion transfer method has high density and excellent sharpness, and is suitable for recording binary images such as characters and line drawings. In addition, by using a thermal transfer sheet having a heat-fusible colored ink layer of yellow, magenta, cyan, black, etc., and superimposing each heat-fusible colored ink layer on an image receiving sheet and printing and recording, multicolor by subtractive color mixing. Alternatively, a color image can be formed.

  In the fusion transfer method, development for improving the printing quality (transferability) has been performed. For example, Patent Literature 1 discloses a thermal transfer sheet in which a specific resin component is blended on a base sheet via a release layer. Patent Document 2 discloses a thermal transfer sheet in which a release layer and a coloring adhesive layer are sequentially provided on a base material, and the coloring adhesive layer does not contain a heat-fusible material and contains specific particles in a specific ratio. ing.

  As described above, with the development of the thermal transfer sheet, in recent years, it has been required to reduce the thermal energy of the thermal head in order to save energy and reduce the load on the thermal transfer printer. There is a need for a thermal transfer sheet that is excellent in printing quality, such as being capable of transferring fine lines in the low energy state.

JP-A-2011-181181 JP 2000-177252 A

  The present invention has been made in such a situation, at least on one side of the substrate sheet, at least a release layer, an intermediate layer, a thermal transfer sheet provided with a coloring layer sequentially, under conditions where the applied energy in printing is low, An object of the present invention is to provide a thermal transfer sheet capable of transferring fine lines and having excellent print quality.

  The above object is achieved by the present invention described below. That is, on one surface of the base material sheet, at least in part, a release layer, an intermediate layer, a thermal transfer sheet provided with a coloring layer in order, wherein the intermediate layer contains at least an inorganic colloid material. Is a thermal transfer sheet.

  The thermal transfer sheet, wherein the inorganic colloid material is at least one of alumina sol and colloidal silica.

  ADVANTAGE OF THE INVENTION According to this invention, the transfer of a thin line was possible under the conditions where the applied energy in printing was low, and it became possible to provide the thermal transfer sheet excellent in printing quality. Further, the thermal transfer sheet of the present invention has excellent interlayer adhesion of the intermediate layer.

FIG. 1 is a schematic sectional view showing one embodiment of a thermal transfer sheet of the present invention. FIG. 9 is a diagram showing a print pattern (white line and black line) of transfer conditions in the evaluation of fine line reproducibility.

(Thermal transfer sheet)
Next, embodiments of the thermal transfer sheet of the present invention will be described in detail.
FIG. 1 is a schematic cross-sectional view showing one embodiment of the thermal transfer sheet of the present invention, and a thermal transfer sheet 1 in which a release layer 3, an intermediate layer 4, and a coloring layer 5 are sequentially provided on one surface of a base sheet 2. In this configuration, a back layer 6 is provided on the other surface of the base sheet 2. Hereinafter, each layer constituting the thermal transfer sheet of the present invention will be described in detail.

(Base sheet)
As the base sheet 2 used in the thermal transfer sheet of the present invention, the same base sheet as that used in the conventional thermal transfer sheet can be used as it is, and other base sheets can be used. Not done. Specific examples of preferable base sheet include, for example, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chloride rubber, ionomer, etc. Papers such as plastic film, condenser paper, paraffin paper and the like, and any of these may be combined.

  The thickness of the base sheet can be appropriately changed depending on the material so that the strength and the thermal conductivity are appropriate, but is preferably about 2 to 12 μm in view of the printing sensitivity. That is, when the thickness is 2 μm or more, sufficient strength as a base sheet is obtained, and when the thickness is 12 μm or less, heat during printing is sufficiently transmitted to the colored layer, and transferability is good. is there.

(Release layer)
The release layer 3 is provided between the base sheet and the intermediate layer of the thermal transfer sheet of the present invention. This release layer can reliably and easily transfer the intermediate layer and the colored layer to the transfer target. The release layer can be formed from, for example, a binder resin and a release material. Examples of the binder resin include thermoplastic resins such as polymethyl methacrylate, polyethyl methacrylate, acrylic resins such as polybutyl acrylate, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, polyvinyl alcohol, polyvinyl butyral, etc. Vinyl resins, cellulose derivatives such as ethylcellulose, nitrocellulose, and cellulose acetate, or unsaturated polyester resins, polyester resins, polyurethane resins, and aminoalkyd resins that are thermosetting resins.

  In the present invention, the acrylic resin is a polymer of a (meth) acrylic acid monomer or a derivative thereof, a polymer of a (meth) acrylic acid ester monomer or a derivative thereof, a (meth) acrylic monomer and another It includes a copolymer with a monomer or a derivative thereof, and a copolymer of a (meth) acrylate monomer with another monomer or a derivative thereof. Similarly, other “system resins” may include a copolymer with another monomer other than the main component or a derivative thereof.

Further, as the release material, waxes, silicone wax, silicone-based resin, melamine resin, fluorine-based resin, fine powder of talc or silica, a surfactant, a lubricant such as metal soap, or the like can be used. The release layer was prepared by dissolving or dispersing the above-described necessary materials with a suitable solvent to prepare a release layer coating liquid, and using a gravure printing method, a screen printing method, or a gravure plate on the substrate sheet. It can be formed by coating and drying by means such as a reverse coating method. The coating amount is about 0.05 to 1 g / m ² when dried.

(Intermediate layer)
The intermediate layer 4 provided in the thermal transfer sheet of the present invention contains at least an inorganic colloid material, and contains the inorganic colloid material and a binder resin as main components. In the present invention, a heat transfer sheet provided with a release layer, an intermediate layer, and a coloring layer sequentially on one surface of a substrate sheet, in particular, an intermediate layer containing an inorganic colloid material, whereby the intermediate layer and the coloring layer are separated from the thermal transfer sheet. The transferability at the time of exfoliation and transfer to a transfer receiving body is improved, and thin lines can be transferred under conditions where the applied energy in printing is low, so that an image can be formed with excellent printing quality.

  By providing this intermediate layer, the mechanism of improving the transferability is not clear at present, but the presence of the intermediate layer causes the heat applied to the intermediate layer and the colored layer from a heating means such as a thermal head to be applied. It is supposed that the transferability of the transfer layer (the intermediate layer and the colored layer) including the colored layer can be sufficiently maintained in the intermediate layer and the colored layer. In other words, it is considered that the intermediate layer plays a role of preventing the heat applied to the intermediate layer and the colored layer from diffusing toward the base sheet.

  Examples of the above-mentioned inorganic colloid materials include colloidal silica, alumina sol, colloidal alumina, cationic aluminum oxide and hydrates thereof. Among them, colloidal silica and alumina sol are preferred. Although the detailed reason why colloidal silica and alumina sol are preferred is not clear at present, colloidal silica and alumina sol tend to have higher thermal conductivity than other inorganic colloid materials, and this high thermal conductivity. This is considered to contribute to the improvement of the transferability of the thermal transfer sheet.

  The above-mentioned inorganic colloid material is a colloid obtained by dispersing a metal oxide such as silica or alumina as a hydrate in a dispersion medium such as water, that is, preferably used in a sol state. The alumina colloid material will be described as an example of the inorganic colloid material, but the inorganic colloid material is not limited to alumina sol. Alumina itself is a powder, which is an aggregate even when dispersed, but alumina sol is a colloid in which alumina hydrate is dispersed in a dispersion medium such as water. Alumina sol can be viewed as a dispersion of primary particles of alumina. As the alumina particles in the alumina sol, feather-like particles are preferably used.

  The particles dispersed in the above-mentioned inorganic colloidal material have a shape such as a sphere, a feather, and a rod. In any case, the size of the particles is preferably 10 μm or less as primary particles. It is preferable that the above-mentioned inorganic colloid material mainly contains an inorganic colloid material having a primary particle size of 10 μm or less. The above-mentioned "mainly" means 50% by mass or more based on the total mass of the inorganic colloid material contained in the intermediate layer. When the size of the primary particles contains an inorganic colloid material of 10 μm or less, the transparency of the intermediate layer is high, and the hue of the colored layer in the printed portion (printed matter) transferred to the transfer object is reduced. This is preferable because it can be faithfully reproduced. Although there is no particular limitation on the preferred lower limit of the inorganic colloid material, the size of the primary particles is about 0.1 μm.

  The binder resin in the intermediate layer is preferably a binder resin that can satisfy the adhesion between the release layer and the colored layer. Examples of such a binder resin include a urethane resin, a polyester resin, a vinyl resin such as a polyvinylpyrrolidone resin and a polyvinyl alcohol resin, and a polyamide epoxy resin. There is no particular limitation on the content of the inorganic colloid material and the binder resin in the intermediate layer, but the content of the inorganic colloid material is preferably 5% by mass or more and 100% by mass or less based on the total mass of the inorganic colloid material and the binder resin. It is particularly preferably from 50% by mass to 90% by mass. By setting the content of the inorganic colloid material within this range, the transferability of the thermal transfer sheet can be further improved, and when printing, excellent printing quality such as the ability to transfer fine lines in a low energy state. Becomes

The method for forming the intermediate layer is not particularly limited, and the coating liquid for an intermediate layer is obtained by dispersing or dissolving the above-exemplified binder resin, the inorganic colloid material, and additives to be added as necessary in an appropriate solvent. Can be prepared and applied to the release layer by a method such as gravure coating or gravure reverse coating, followed by drying. Although there is no particular limitation on the coating amount of the intermediate ^{layer, 0.1g / m 2 ~5g / m} 2 is preferably about in coating amount after drying.

(Colored layer)
In the present invention, the coloring layer 5 is provided on the above-mentioned intermediate layer. The coloring layer is a hot-melt ink layer and contains a conventionally known coloring agent and a binder, and, if necessary, various mineral oils, vegetable oils, higher fatty acids such as stearic acid, plasticizers, antioxidants, fillers and the like. Is used.

  Examples of the wax component used as the binder include microcrystalline wax, carnauba wax, and paraffin wax. Furthermore, various types such as Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, beeswax, spermaceti, Ibota wax, wool wax, shellac wax, candelilla wax, petrolactam, polyester wax, partially modified wax, fatty acid ester, fatty acid amide, etc. Is used. Among them, a wax component having a melting point of 50 to 85 ° C. is particularly preferable. When the temperature is 50 ° C or higher, the storage stability is good, and when the temperature is 85 ° C or lower, sufficient sensitivity is obtained.

  As the resin component used as the binder, for example, ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, polyethylene, polystyrene, polypropylene, polybutene, petroleum resin, vinyl chloride resin, vinyl chloride-vinyl acetate copolymer Coalesce, polyvinyl alcohol, vinylidene chloride resin, methacrylic resin, polyamide, polycarbonate, fluororesin, polyvinyl formal, polyvinyl butyral, acetylcellulose, nitrocellulose, polyvinyl acetate, polyisobutylene, ethylcellulose, polyacetal and the like. Those having a relatively low softening point used as a heat-sensitive adhesive, for example, a softening point of 50 to 80 ° C are preferred.

  The colorant can be appropriately selected from known organic or inorganic pigments or dyes. For example, a colorant having a sufficient color density and not discoloring or fading by light, heat, or the like is preferable. Further, it may be a substance that develops color by heating or a substance that develops color when it comes into contact with a component applied to the surface of the transfer-receiving body. Further, the color of the colorant is not limited to cyan, magenta, yellow, and black, and various colors of colorants can be used.

  As the coloring agent, in addition to those having the above-mentioned cyan, magenta, yellow, and black colors, those representing a metal color, a fluorescent color, and the like can be used. As a coloring agent having a metallic color, aluminum powder can be used, and the aluminum powder is preferably in the form of flakes. Even if the aluminum powder itself has been subjected to surface treatment with a coloring pigment or a resin, or surface treatment, Anything that is not done can be used. The aluminum powder includes a non-leafing type in which aluminum flakes are uniformly dispersed and arranged in a coating film, and a leafing type in which aluminum flakes float on the coating film surface and are arranged in parallel by surface tension. The leafing type improves the glossiness, but has a large amount of aluminum flakes on the surface and a small amount of binder, and thus tends to have poor adhesion to the transfer receiving body. Further, when it is desired to further enhance the glossiness, an aluminum powder obtained by pigmenting an aluminum vapor-deposited film can be used, and a color tone close to plating can be obtained, and it can be manufactured by the following method.

1. A release surface is formed on a roll or continuous carrier sheet.
2. Aluminum is adhered to the peeled surface by a vapor deposition method to form an aluminum film.
3. The exfoliated surface is dissolved to separate the aluminum film and the carrier sheet from each other.
4. The above separated aluminum film is subdivided into dimensions suitable for use in a coating ink.
The leafing-type aluminum powder produced as described above has a thickness of about 0.01 to 0.05 μm, an average size of about 10 to 50 μm, and is in the form of scale.

  Further, as a coloring agent having a fluorescent color, a fluorescent pigment as described in Japanese Patent No. 4121618 can be used. In addition, a fluorescent dye which is white or colorless under visible light and emits fluorescence by absorbing ultraviolet light or infrared light can be used as the coloring agent. Examples of the fluorescent dye include those described in Japanese Patent No. 4440713.

  Further, a heat conductive substance may be blended as a filler for the binder in order to impart good heat conductivity and hot melt transfer property to the colored layer. Examples of such a filler include carbonaceous substances such as carbon black, and metals and metal compounds such as aluminum, copper, tin oxide, and molybdenum disulfide.

  The formation of the colored layer includes the above-described colorant component and binder component, and further, depending on these, various kinds of mineral oil, vegetable oil, higher fatty acids such as stearic acid, plasticizers, antioxidants, fillers, and the like. Additives, water, a coating solution for forming a colored layer prepared by mixing and adjusting solvent components such as an organic solvent, by a conventionally known method such as hot melt coating, hot lacquer coating, gravure coating, gravure reverse coating, and roll coating. Do. Also, there is a method of forming using an aqueous or non-aqueous emulsion coating liquid.

The thickness of the coloring layer should be determined so that the required printing density and thermal sensitivity can be harmonized, and is preferably in the range of 0.5 to 8 g / m ² in a coating amount at the time of drying. A range from 2.5 to 6 g / m ² is particularly preferred.

(Back layer)
In the thermal transfer sheet of the present invention, if necessary, adverse effects such as sticking and wrinkling due to heat from a thermal head or the like as a thermal transfer means are prevented on the back surface of the base sheet, that is, on the surface opposite to the surface provided with the colored layer. Therefore, the back layer 6 can be provided. As the resin for forming the back layer, any conventionally known resin may be used, for example, polyvinyl butyral resin, polyvinyl acetoacetal resin, polyester resin, vinyl chloride-vinyl acetate copolymer, polyether resin, polybutadiene resin, styrene- Butadiene copolymer, acrylic polyol, polyurethane acrylate, polyester acrylate, polyether acrylate, epoxy acrylate, urethane or epoxy prepolymer, nitrocellulose resin, cellulose nitrate resin, cellulose acetopropionate resin, cellulose acetate butyrate resin, Cellulose acetate hydrodiene phthalate resin, cellulose acetate resin, polyamide resin, polyimide resin, polyamide imide resin, polycarbonate resin, salt Polyolefin resins, and chlorinated polyolefin resins.

  Phosphoric acid esters, silicone oils, graphite powders, silicone graft polymers, fluorine graft polymers, acrylic silicone graft polymers, acrylic siloxanes, aryl siloxanes, etc. And a polyol, for example, a polyalcohol polymer compound, a polyisocyanate compound and a phosphate compound, and more preferably a filler is further added.

The back layer is prepared by dissolving or dispersing the above-described resin, the slipperiness imparting agent, and the filler with a suitable solvent to prepare a back layer forming ink. For example, it can be formed by applying a gravure printing method, a screen printing method, a reverse coating method using a gravure plate, or the like, followed by drying. The application amount of the back layer is sufficient as long as the fusion prevention and the lubricity can be achieved, and is usually about 0.1 to 3 g / m ² when dried.

<Transfer object>
The transfer object that can be used for the transfer of the thermal transfer sheet according to the present invention is not particularly limited, and examples thereof include a conventionally known substrate provided with a receptor layer having a dye receiving property on a substrate. Examples of the substrate in the transfer object include plain paper, high-quality paper, tracing paper, and plastic film, and the substrate is not particularly limited. The receiving layer in the transfer object can be formed by a coating method, a forming method using a thermal head or a hot roll, or the like. It is not necessary to provide a receptor layer on the transfer object as long as the substrate itself has a dye receiving property.

<Transfer method>
The transfer to the transfer object using the transfer sheet according to the present invention can be performed directly on the transfer object using a conventionally known thermal transfer printer (direct), or can be performed after the transfer onto the receiving layer provided on the intermediate transfer recording medium (primary transfer). Transfer), or by transferring (retransferring) the receiving layer of the intermediate transfer recording medium to a transfer receiving body. For the thermal transfer printer, for example, the transfer conditions may be set separately such as for sublimation transfer, for hot-melt transfer, and for protective layer transfer, or may be performed by appropriately adjusting the printing energy for each with a common printer. You may. The heating means is not particularly limited, and transfer may be performed using a thermal head, a hot plate, a hot stamper, a heat roll, a line heater, an iron, or the like.

  Next, the present invention will be described more specifically with reference to examples. In the following description, “parts” or “%” is based on mass unless otherwise specified.

(Example 1)
A base sheet is coated with a 4.5 μm-thick biaxially stretched polyethylene terephthalate film (manufactured by Toray Industries, Inc., Lumirror) on one surface, and a back layer coating solution having the following composition is dried by a wire bar coating method. Was applied so as to have a coating amount of 1.0 g / m ² and dried to form a back layer. Next, a coating liquid for a release layer having the following composition is gravure coated on the surface opposite to the surface on which the back layer of the base sheet is formed, so that the coating amount at the time of drying is 0.5 g / m ^2. It was applied and dried to form a release layer. Further, on the release layer, an intermediate layer coating liquid 1 having the following composition was applied by gravure coating so that the coating amount at the time of drying was 1.5 g / m ² , followed by drying. Formed. Further, on the intermediate layer, a coating solution for a coloring layer having the following composition is applied by gravure coating so that the coating amount at the time of drying becomes 1.5 g / m ² and dried to form a coloring layer. Then, a thermal transfer sheet of Example 1 was produced.

(Coating liquid composition for back layer)
・ Polyvinyl butyral resin (S-REC BX-1, manufactured by Sekisui Chemical Co., Ltd.)
3.6 parts polyisocyanate (Bernock D750, manufactured by DIC Corporation) 8.6 parts phosphate ester surfactant (Plysurf A208S, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
2.8 parts · Talc (Micro Ace P-3, manufactured by Nippon Talc Corporation) 0.7 parts · Methyl ethyl ketone 32.0 parts · Toluene 32.0 parts

(Coating liquid for release layer)
・ Polymethyl methacrylic acid (PMMA) (Dianal BR-87 Mitsubishi Rayon Co., Ltd.)
20 parts ・ Toluene 40 parts ・ MEK (methyl ethyl ketone) 40 parts

(Coating liquid for intermediate layer 1)
・ 3 parts of polyvinylpyrrolidone resin (K-90 ISP) ・ 30 parts of alumina sol (average primary particle size: 10 × 100 nm, solid content 10%, alumina sol 200 Nissan Chemical Industry Co., Ltd.) ・ 50 parts of water ・ IPA (Isopropyl alcohol) 17 parts

(Coating solution for colored layer)
30.2 parts of coloring agent (carbon black dispersing agent, solid content 46%, compounding ratio of carbon black 40%, dispersing agent 6%, remainder toluene / ethyl acetate = 1/1) 30.2 parts vinyl chloride-vinyl acetate 37.0 parts of copolymer (trade name: Solvain CL, solid content: 30%, glass transition point: 75 ° C., weight average molecular weight: 20,000, manufactured by Nissin Chemical Industry Co., Ltd.): toluene / methyl ethyl ketone = 50/50 (mass ratio) 32.8 parts

(Example 2)
A thermal transfer sheet of Example 2 was produced in the same manner as in Example 1 except that the coating solution 1 for the intermediate layer was changed to the following composition in the thermal transfer sheet of Example 1 described above.
(Coating liquid for intermediate layer 2)
・ 3 parts of polyvinylpyrrolidone resin (K-90 ISP) ・ 30 parts of colloidal silica (average particle size: 4-6 nm, solid content 10%, Snowtec OSX Nissan Chemical Industries, Ltd.) ・ 50 parts of water ・ IPA (Isopropyl alcohol) 17 parts

(Example 3)
A thermal transfer sheet of Example 3 was produced in the same manner as in Example 1 except that the coating liquid 1 for the intermediate layer was changed to the following composition in the thermal transfer sheet of Example 1 described above.
(Coating liquid for intermediate layer 3)
・ Urethane resin (solid content 35%, F-2850D Daiichi Kogyo Seiyaku Co., Ltd.) 10 parts ・ Alumina sol (average primary particle size: 10 × 100 nm, solid content 10%, alumina sol 200) Nissan Chemical Industries, Ltd. 15 parts, water 37.5 parts, IPA (isopropyl alcohol) 37.5 parts

(Example 4)
A thermal transfer sheet of Example 4 was produced in the same manner as in Example 1 except that the coating liquid 1 for the intermediate layer was changed to the following composition in the thermal transfer sheet of Example 1 described above.
(Coating liquid 4 for middle layer)
・ 3 parts of polyvinyl alcohol (PVA-203 Kuraray Co., Ltd.) ・ 15 parts of alumina sol (average primary particle size: 10 × 100 nm, solid content 10%, alumina sol 200 Nissan Chemical Industries, Ltd.) ・ 37.5 parts of water・ Methanol 37.5 parts

(Example 5)
A thermal transfer sheet of Example 5 was produced in the same manner as in Example 1 except that the coating solution 1 for the intermediate layer was changed to the following composition in the thermal transfer sheet of Example 1 described above.
(Coating liquid for intermediate layer 5)
-Alumina sol (average primary particle size: 10 x 100 nm, solid content 10%, alumina sol 200 Nissan Chemical Industries, Ltd.) 60 parts-Water 30 parts-IPA (isopropyl alcohol) 10 parts

(Example 6)
A thermal transfer sheet of Example 6 was produced in the same manner as in Example 1 except that the coating solution 1 for the intermediate layer was changed to the following composition in the thermal transfer sheet of Example 1 described above.
(Coating liquid for intermediate layer 6)
・ 0.6 parts of polyvinylpyrrolidone resin (K-90 ISP) ・ 54 parts of alumina sol (average primary particle size: 10 × 100 nm, solid content 10%, alumina sol 200 Nissan Chemical Industry Co., Ltd.) ・ 34 parts of water・ 11.5 parts of IPA (isopropyl alcohol)

(Example 7)
A thermal transfer sheet of Example 7 was produced in the same manner as in Example 1 except that the coating liquid 1 for the intermediate layer was changed to the following composition in the thermal transfer sheet of Example 1 described above.
(Coating liquid for intermediate layer 7)
・ 1.8 parts of polyvinylpyrrolidone resin (K-90 ISP) ・ 42 parts of alumina sol (average primary particle size: 10 × 100 nm, solid content 10%, alumina sol 200 Nissan Chemical Industries, Ltd.) ・ 42 parts of water・ 14.5 parts of IPA (isopropyl alcohol)

(Example 8)
A thermal transfer sheet of Example 8 was produced in the same manner as in Example 1 except that the coating liquid 1 for the intermediate layer was changed to the following composition in the thermal transfer sheet of Example 1 described above.
(Coating liquid for intermediate layer 8)
-4.8 parts of polyvinylpyrrolidone resin (K-90 ISP)-12 parts of alumina sol (average primary particle size: 10 x 100 nm, solid content 10%, alumina sol 200 Nissan Chemical Industry Co., Ltd.) 12 parts-Water 62 parts・ 22 parts of IPA (isopropyl alcohol)

(Example 9)
The thermal transfer sheet produced in the same manner as in Example 1 was used as the thermal transfer sheet of Example 9.

(Example 10)
The thermal transfer sheet produced in the same manner as in Example 2 was used as the thermal transfer sheet of Example 10.

(Example 11)
The thermal transfer sheet produced in the same manner as in Example 3 was used as the thermal transfer sheet of Example 11.

(Example 12)
The thermal transfer sheet produced in the same manner as in Example 4 was used as the thermal transfer sheet of Example 12.

(Comparative Example 1)
The structure of the thermal transfer sheet of Comparative Example 1 was the same as that of Example 1 except that the intermediate layer was omitted in the configuration of the thermal transfer sheet of Example 1 above, and the rest was the same as in Example 1. Was prepared.

(Comparative Example 2)
A thermal transfer sheet of Comparative Example 2 was produced in the same manner as in Example 1 except that the composition of the thermal transfer sheet of Example 1 was changed to the following composition for the coating liquid 1 for the intermediate layer.
(Coating liquid for intermediate layer 10)
・ 3 parts of polyvinylpyrrolidone resin (K-90 ISP) ・ 50 parts of water ・ 17 parts of IPA (isopropyl alcohol)

(Performance evaluation of thermal transfer sheet)
Using the thermal transfer sheets prepared in Examples 1 to 8 and Comparative Examples 1 and 2, print quality (print quality) and interlayer adhesion of the intermediate layer were evaluated by the following methods.
(Print quality A)
Using the thermal transfer sheets prepared in Examples and Comparative Examples, and a polyvinyl chloride card under the following conditions as a transfer receiving body, the line width was about 0.17 mm ｛(1 inch / 300) × 2 under the following printing conditions. In 印字, two patterns were printed, one having a fine line pattern with an interval of 1 mm in the flow direction and the other having a fine line pattern in a direction perpendicular to the flow direction. This pattern was used as a positive pattern, and a negative pattern corresponding to the positive pattern was printed. In these printed matters, the presence or absence of blurring or crushing of the image area was visually observed and evaluated.

<PVC card>
For the polyvinyl chloride card, a center core (thickness 0.2 mm) having the following composition for a card base material is prepared, and a transparent sheet (thickness 0.15 mm) having the following composition is prepared. Then, the transparent sheet was thermocompression-bonded to produce a three-layer card (54 × 86 cm).

(Composition of center core)
・ 100 parts of vinyl chloride compound (degree of polymerization 800, content of additives such as stabilizers about 10%)
・ White pigment (titanium oxide) 10
Part / plasticizer (dioctyl phthalate) 0.5
Part (transparent sheet composition)
・ 100 parts of vinyl chloride compound (degree of polymerization 800, content of additives such as stabilizers about 10%)
・ Plasticizer (dioctyl phthalate) 0.5 parts

(Printing conditions)
・ Thermal head: KGT-217-12MPL20 (manufactured by Kyocera Corporation)
Heating element average resistance value: 3195 (Ω)
・ Printing density in the main scanning direction: 300 dpi
-Print density in the sub-scanning direction: 300 dpi
-Applied power: 0.13 (w / dot)
・ One line cycle: 5 (msec.)
・ Printing start temperature: 40 (° C)

The evaluation of the blur of the image area was performed according to the following criteria.
A: Good without blurring of image area.
：: The image area is partially blurred, but can be easily read.
Δ: The image area is blurred, but readable.
X: The image area is entirely blurred, unreadable and defective.

In addition, the evaluation of the collapse of the image area was performed according to the following criteria.
：: Good, with no collapse of the image area.
：: The image area is partially broken, but can be easily read.
Δ: The image area is crushed but readable.
×: The image area is entirely crushed, cannot be read, and is defective.

(Print quality B)
First, an intermediate transfer medium was manufactured as follows.
(Preparation of intermediate transfer medium)
A 12 μm thick polyethylene terephthalate (PET) film was used as a substrate, and a coating liquid for a release layer having the following composition was applied to one surface of the substrate by a gravure coating method to a thickness of 1.0 μm after drying. It was applied and dried to form a release layer. Next, the following coating liquid for a primer layer was applied on the release layer by gravure coating to a thickness of 1.0 μm after drying, and dried to form a primer layer. Next, the following coating liquid for a protective layer was applied on the primer layer by gravure coating to a thickness of 2.0 μm after drying, and dried to form a protective layer. Next, the following coating liquid 1 for a receiving layer was applied onto the protective layer by a gravure coating method so as to have a thickness of 2.5 μm after drying, and dried to form a receiving layer, thereby producing an intermediate transfer medium 1. . The release layer / primer layer / protective layer / receptive layer constitute a transfer layer of the intermediate transfer medium, and the transfer layer is a layer that is re-transferred onto the transfer object.

<Coating liquid for release layer>
・ Acrylic resin (Mitsubishi Rayon Co., Ltd., trade name: BR-87) 95 parts ・ Polyester resin (Toyobo Co., Ltd., trade name: Byron 200) 5 parts ・ Toluene 200 parts ・ MEK 200 parts <Protection Coating liquid for layer formation>
-20 parts of polyester-based resin (trade name: UE-9885, manufactured by Unitika Ltd., number average molecular weight: 6000, Tg = 82 ° C)-40 parts of toluene-40 parts of MEK <Coating liquid for receiving layer>
95 parts of vinyl chloride-vinyl acetate copolymer (Nissin Chemical Industry Co., Ltd., trade name: CNL, Mn: 12000) Epoxy-modified silicone (Shin-Etsu Chemical Co., Ltd., trade name: KP-1800U)
5 parts ・ Toluene 200 parts ・ Methyl ethyl ketone 200 parts

Next, using the transfer sheets manufactured in Examples 9 to 12 and the test printer described below, a print pattern was transferred onto the receiving layer of the intermediate transfer medium manufactured above.
(Test printer)
-Thermal head: KEE-57-12 GAN2-STA (manufactured by Kyocera Corporation)
Heating element average resistance value: 3303 (Ω)
・ Printing density in the main scanning direction: 300 dpi
・ Print density in the sub-scanning direction; 300 dpi
・ Printing voltage: 18 (V)
-1 line cycle; 3.0 (msec.)
・ Printing start temperature: 35 (° C)
・ Pulse duty ratio: 85%
<Transfer conditions>
-Printing conditions: 3.0 msec / line, 18.5 V
-Print pattern: Print pattern shown in Fig. 2 (white line and black line)
・ Transfer object: PVC card

Subsequently, under the following retransfer conditions, the transfer layer of each image formed product was retransferred onto a white PVC card, and the ratio of the area of the white and black thin line portions of the produced print was calculated. The printing quality was evaluated according to the evaluation criteria.
(Retransfer conditions)
・ Laminator: Lami Packer LPD3212 (Fujipla)
・ Temperature: 145 ° C, 140 ° C, 135 ° C
・ Speed: 0.8 (set value)

(Interlayer adhesion of intermediate layer)
Using the thermal transfer sheet prepared in the example and the above-mentioned transfer receiving body, when printing under the above printing conditions, the interlayer adhesion of the intermediate layer of the thermal transfer sheet (the adhesiveness of the release layer and the intermediate layer, and the The adhesion of the colored layer was evaluated according to the following evaluation criteria. In the case where the interlayer adhesion of the intermediate layer of the thermal transfer sheet is poor, when printing is performed with high heat, a phenomenon occurs in which the entire release layer is not completely transferred and remains on the substrate sheet side.
◎: The area of the release layer where the transfer was not performed normally was 0%.
：: The area of the release layer that was not normally transferred was more than 0% and less than 10%.
Δ: The area of the release layer where the transfer was not performed normally was 10% or more and less than 30%.
×: The area of the release layer where the transfer was not performed normally was 30% or more.

  Table 1 shows the evaluation results of the print quality and the interlayer adhesion of the intermediate layer in the above Examples and Comparative Examples.

  As shown in Table 1, in the printed matter using the thermal transfer sheets of the present invention of Examples 1 to 12, all the image portions, that is, fine lines, were readable or not sparse. This was able to transfer a fine line under the condition of low applied energy in printing, and was excellent in printing quality. On the other hand, in the printed matter of the thermal transfer sheet of Comparative Example 1, fine lines were blurred and crushed, and a problem occurred in the transfer of the thin lines under the condition where the applied energy in printing was low, resulting in poor print quality. Further, the printed matter of the thermal transfer sheet of Comparative Example 2 was slightly blurred with fine lines, was crushed, and was defective. Further, the thermal transfer sheets of Examples 1 to 12 of the present invention were excellent in interlayer adhesion of the intermediate layer.

DESCRIPTION OF SYMBOLS 1 Thermal transfer sheet 2 Substrate sheet 3 Release layer 4 Intermediate layer 5 Colored layer 6 Back layer

Claims (2)

A thermal transfer sheet in which a release layer, an intermediate layer, and a coloring layer are sequentially provided on at least a part of one surface of a base sheet, wherein the intermediate layer is made of 70% by mass or more and 100% by mass or less of an inorganic colloid material. A thermal transfer sheet characterized by containing.   The thermal transfer sheet according to claim 1, wherein the inorganic colloid material is at least one of alumina sol and colloidal silica.

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