JP2006306089A - Thermal transfer sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal transfer sheet which has an electrically conductive primer layer having enough adhesive properties and heat resistance without using a binder resin, is excellent in antistatic properties, and hardly generates a trouble during printing. <P>SOLUTION: In the thermal transfer sheet provided with a thermal transfer coloring material layer on one face of a substrate sheet and a heat-resistant lubricating layer on the other face of the substrate sheet through the primer layer, the thermal transfer sheet is characterized in that the primer layer is formed by using electrically conductive colloidal inorganic pigment ultra-fine particles. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a thermal transfer sheet.

As a thermal transfer sheet used for image formation using thermal transfer, a sublimation thermal transfer sheet in which a dye layer composed of a thermal diffusion dye (sublimation dye) is provided on a substrate sheet such as a plastic film, or the dye layer instead There is known a heat-melting type thermal transfer sheet provided with an ink layer made of pigment and wax. These thermal transfer sheets are heated from the back by a thermal head, and form an image by transferring the dye of the dye layer or the pigment of the ink layer to a transfer material.

When the base film is a thermoplastic film, these thermal transfer sheets are charged with static electricity because the surface specific resistance of the contact surface with the thermal head increases when an image is formed with a thermal head. There was a problem that it was easy. In particular, in the case of a heat-melt type thermal transfer sheet, most of the ink layer has wax as a main component, and thus tends to be easily charged.
When the thermal transfer sheet is charged, dust or the like adheres to the surface of the thermal transfer sheet or the thermal head, and the resolution of the image to be formed is reduced. The transfer material such as paper is charged, and the transportability of the transfer material is reduced. Problems arise.
In order to prevent these problems from occurring, means for imparting antistatic properties to the thermal transfer sheet have been studied conventionally.

As a means for imparting antistatic properties to the thermal transfer sheet, for example, it is known to provide a primer layer containing an antistatic agent (such as a conductive agent).
As a thermal transfer sheet provided with a primer layer containing an antistatic agent, a primer layer containing a sulfonated polyaniline as an antistatic agent and a curable resin such as a polyester resin is used, and a heat transferable color material layer of a base sheet is used. Patent Document 1 proposes a thermal transfer sheet provided on the surface opposite to the side provided with a heat-resistant slipping layer.

As a thermal transfer sheet using the same antistatic agent in the same layer structure as the sheet described in Patent Document 1, Patent Document 2 discloses that a binder resin constituting a primer layer is a resin having specific viscoelastic properties (for example, water dispersibility). Alternatively, those limited to water-soluble polyester resins and the like have been proposed.

As a thermal transfer sheet provided with a primer layer containing an antistatic agent, a low resistance primer layer in which a metal oxide powder such as indium and tin is dispersed in a binder resin as a conductive agent, a base material, a hot-melt ink layer, Patent Document 3 discloses a heat-sensitive transfer material provided between the two.

However, in the technique for forming a conductive primer layer using the above conductive agent (antistatic agent) and binder resin, if the heat resistance of the binder resin is insufficient, the primer layer is heated by the heat of the thermal head during printing. In addition to the problem that the ink is scraped off and print wrinkles are generated, the compatibility between the conductive agent and the binder resin must be taken into account, and there is a problem that the combination of the materials is naturally limited.

The conductive layer is formed using a specific metal oxide. The transparent ceramic vapor-deposited layer formed by vacuum vapor deposition of the specific metal oxide is used as a heat-resistant treatment layer, and a polyester film substrate. Patent Document 4 proposes a thermal transfer recording medium provided on the surface opposite to the side on which the ink layer is provided. In Patent Document 4, only TiO ₂ is used in the examples, but Al ₂ O ₃ is exemplified as the specific metal oxide.
The recording medium provided with the ceramic vapor-deposited layer, however, has a problem that even if it has heat resistance, a special apparatus for vapor-depositing is essential and the manufacturing cost is high.
JP 2000-272254 A JP 2001-1653 A JP-A-2-20390 JP-A-8-267742

The object of the present invention is to provide a conductive primer layer having sufficient adhesion and heat resistance without using a binder resin in view of the above-mentioned current situation, excellent in antistatic properties, and less likely to cause trouble during printing. It is in providing a sheet.

The present invention provides a thermal transfer sheet in which a heat transferable color material layer is provided on one side of a base sheet, and a heat resistant slipping layer is provided on the other side of the base sheet via a primer layer. A thermal transfer sheet formed by using ultrafine particles of conductive colloidal inorganic pigment.
The present invention is described in detail below.

As shown in FIG. 1, for example, the thermal transfer sheet of the present invention has, as shown in FIG. 1, a thermal transfer color material layer (2) is formed on one surface and the other surface is formed. The heat-resistant slipping layer (4) is formed through the primer layer (3).

(Substrate sheet)
As the substrate sheet in the present invention, there can be used those made of various papers, resins and the like having mechanical properties that can withstand the heating during image formation and have no trouble in handling.
Examples of the paper include condenser paper and paraffin paper.
Examples of the resin include polyethylene terephthalate, 1,4-polycyclohexylenedimethylene terephthalate, polyethylene naphthalate, polyphenylene sulfide, polystyrene, polyethylene, polypropylene, polysulfone, aramid, polycarbonate, polyvinyl alcohol, cellophane, cellulose derivatives such as cellulose acetate, Polyvinyl chloride, nylon, polyimide, ionomer and the like can be mentioned. Among them, polyethylene terephthalate, polyethylene naphthalate, or a polyester composed of a mixture thereof is preferable, and polyethylene terephthalate is more preferable.

The substrate sheet in the present invention may be in a sheet form or a continuous film form.
Generally the thickness of the said base material sheet should just be 0.5-50 micrometers, Preferably it is 1-10 micrometers, More preferably, it is 2-6 micrometers.
For example, when the base sheet is a stretched film, the thickness unevenness of the base sheet is within ± 5% of the average thickness in both the MD direction and the TD direction in terms of running performance of the thermal head, prevention of printing unevenness, and the like. It is preferable.
The thickness of the substrate sheet is measured by a micrometer method in accordance with JIS C 2151-1990.

In the base sheet, since the primer layer is formed by using conductive colloidal inorganic pigment ultrafine particles, the base sheet and the primer layer are excellent in adhesiveness. In order to improve, it is preferable to perform an adhesion treatment on the surface of the base material on which the primer layer and the dye layer are formed.
Examples of the above-mentioned adhesion treatment include corona discharge treatment, flame treatment, ozone treatment, ultraviolet treatment, radiation treatment, surface roughening treatment, chemical treatment, plasma treatment, low temperature plasma treatment, primer treatment, grafting treatment, etc. Modification techniques can be applied. Only one kind of the above-mentioned adhesion treatment may be performed, or two or more kinds may be performed.
In the present invention, among the above-mentioned adhesion treatments, corona discharge treatment or plasma treatment is preferred in that the adhesion between the substrate and the primer layer can be enhanced without increasing the cost.

(Heat transferable color material layer)
The heat transferable color material layer in the present invention is a layer that carries a color material to be printed, and is formed on one surface of the substrate sheet.
The heat transferable color material layer may be formed by sequentially layering layers having different color materials.
When the thermal transfer sheet of the present invention is a sublimation type thermal transfer sheet, the thermal transfer colorant layer is a dye layer containing a sublimation dye, and when it is a hot melt type thermal transfer sheet, an ink layer comprising a pigment and wax. It is.
Hereinafter, although the dye layer containing a sublimation dye is mainly demonstrated, the thermal transfer sheet of this invention is not limited only to a sublimation type thermal transfer sheet.

The dye layer in the present invention is formed by supporting a sublimable dye with a binder resin.
As the sublimation dye, a dye used in a conventionally known sublimation type thermal transfer sheet can be used.
Examples of the sublimable dye include: diarylmethane series; triarylmethane series; thiazole series; methine series such as merocyanine; Oxazines; Cyanomethylenes such as dicyanostyrene and tricyanostyrene; thiazines; azines; acridines; benzeneazos; Azos such as azo and disazo; spiropyrans; indolinospiropyrans; fluorans; rhodamine lactams; naphthoquinones; anthraquinones; quinophthalones; It is. Among these, a dye is appropriately selected and used in consideration of characteristics such as hue, print density, light resistance, storage stability, and solubility in a binder.
The dye is preferably present in an amount of 5 to 90% by mass in the dye layer obtained by coating and drying, and more preferably in an amount of 10 to 70% by mass.

Examples of the binder resin include cellulose resins such as ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, and cellulose butyrate; polyvinyl acetals such as polyvinyl alcohol, polyvinyl acetate, and polyvinyl butyral; polyvinyl pyrrolidone Vinyl resins such as: acrylic resins such as poly (meth) acrylates and poly (meth) acrylamides; polyurethane resins; polyamide resins; polyester resins, among others, heat resistance, dye transferability In view of the above, cellulose resins, vinyl resins, acrylic resins, polyurethane resins, polyester resins and the like are preferable.

The dye layer is formed by applying and drying a dye layer coating solution prepared by appropriately dispersing or dissolving the above dye and binder resin in a solvent or the like on one surface of a base sheet. Can do.
In the dye layer coating solution, the dye can be added so as to be contained in the dye layer within the above range.
In the dye layer coating solution, the total amount of the dye and the binder resin, that is, the solid content concentration can be appropriately selected according to the type of each material used, but is generally 5 to 20% by mass.
In addition to the above-mentioned dye and binder resin, the dye layer coating solution may be added with known additives as necessary. As said additive, the material (release agent) etc. which are added to the below-mentioned release layer are mentioned, for example.
The solvent is not particularly limited as long as it is a conventionally known material for the dye layer coating solution. For example, acetone, water, methanol, methyl ethyl ketone, toluene, ethanol, isopropyl alcohol, cyclohexanone, dimethylformamide [DMF] , Ethyl acetate, a mixed solvent of these solvents, and the like can be used, and among them, a mixed solvent of methyl ethyl ketone and toluene is preferable.

The dye layer coating liquid can be applied by known means such as a gravure printing method, a screen printing method, a reverse roll coating method using a gravure plate, and the like.
When the desired image is monochromatic, the dye layer can be prepared by selecting one color dye and forming one layer containing the dye, and the desired image is full color. In this case, for example, it can be prepared by selecting appropriate cyan, magenta, and yellow (and optionally black) dyes, and forming a layer containing any one of the dyes. it can.
Dried coating amount of the dye layer is preferably from about 0.2-5 g / ^{m 2,} and more preferably is of about 0.4~2g / ^{m 2.}

In the present invention, a release layer may be provided on the surface of the heat transferable color material layer for the purpose of preventing adhesion with the heat transfer image receiving sheet.
Examples of the release layer include a layer formed by adhering an anti-adhesive inorganic powder; a layer made of a resin having excellent release properties such as a silicone polymer, an acrylic polymer, and a fluorinated polymer.
Dried coating weight of the release layer is about 0.01-5 g / ^{m 2,} preferably about 0.05 to 2 g / ^{m 2.}

(Primer layer)
In the present invention, the primer layer is provided on the surface of the base sheet opposite to the heat transferable colorant layer to impart antistatic properties to the heat transfer sheet and to favorably bond the base sheet and the heat resistant slipping layer. Is provided.

The primer layer is formed using conductive colloidal inorganic pigment ultrafine particles.
Examples of the conductive colloidal inorganic pigment ultrafine particles include, for example, metal silicates such as aluminum silicate and magnesium silicate; alumina or alumina hydrate (alumina sol, colloidal alumina, cationic aluminum oxide or hydrate thereof) , Suspicious boehmite, etc.), metal oxides such as magnesium oxide and titanium oxide; carbonates such as magnesium carbonate; etc., conventionally known compounds can be used, but metal oxides and carbonates are preferred, metal Oxides are more preferred, alumina or alumina hydrate is more preferred, and alumina sol is particularly preferred.
The primer layer may be composed of only one kind as the conductive colloidal inorganic pigment ultrafine particles, or may be composed of two or more kinds as the conductive colloidal inorganic pigment ultrafine particles.

The average particle size of the conductive colloidal inorganic pigment ultrafine particles is usually 100 nm or less, preferably 50 nm or less, and particularly preferably 3 to 30 nm.
When the conductive colloidal inorganic pigment ultrafine particles have an average particle size within the above range, the above-described effects relating to antistatic properties and adhesiveness can be sufficiently exhibited.
In the present invention, the conductive colloidal inorganic pigment ultrafine particles may be processed into an acidic type by adding a dispersion stabilizer such as hydrochloric acid or acetic acid for the purpose of facilitating dispersion in a sol form in an aqueous solvent. Alternatively, the fine particle charge may be a cation or may be a surface-treated one.
The conductive colloidal inorganic pigment ultrafine particles in the present invention may be commercial products such as alumina sol 100 (manufactured by Nissan Chemical Industries, Ltd.) and alumina sol 200 (manufactured by Nissan Chemical Industries, Ltd.).
In the present specification, the average particle diameter is measured by observation with an electron microscope.

The primer layer can be generally formed by applying an aqueous primer layer coating liquid composed of conductive colloidal inorganic pigment ultrafine particles on a substrate sheet and drying. The primer layer is more preferably formed by using a sol-gel method described later.
Since the primer layer can be formed using an aqueous primer layer coating solution, in addition to being excellent in antistatic performance, a conventional coating solution in which a conductive agent is dispersed in a binder resin is used. Compared with the formed primer layer, the adhesiveness with a base material sheet is favorable, and since it can form by simple methods, such as a sol gel method, without using binder resin, manufacturing cost is low.

The primer layer coating liquid can be prepared by dispersing conductive colloidal inorganic pigment ultrafine particles in an aqueous medium.
Examples of the aqueous medium in the primer layer coating liquid include water, a water-soluble alcohol such as isopropyl alcohol, a mixed liquid of water and a water-soluble alcohol, and the like.
In the primer layer coating solution, the conductive colloidal inorganic pigment ultrafine particles are preferably 1 to 300 parts by mass with respect to 100 parts by mass of the aqueous medium.

In the present invention, the primer layer coating solution can be applied by a known means in the same manner as the dye layer coating solution.
The primer layer coating solution can be applied in an amount such that the coating amount after drying is 0.1 to 10 g / m ^2. However, in terms of imparting excellent antistatic properties, the coating amount after drying is: Preferably, the coating amount can be 0.15 g / m ² or more, more preferably 0.2 g / m ² or more, and the coating amount after drying is preferably from the viewpoint of sufficient antistatic properties. It can apply | coat in the quantity used as 5 g / m < ² > or less, More preferably 3 g / m < ² > or less.
That is, the primer layer in the present invention can exhibit an antistatic effect even when the amount of conductive colloidal inorganic pigment ultrafine particles used is less than that of a conventional conductive agent.
The drying is usually performed by exposing to 90 to 130 ° C. hot air so that the conductive colloidal inorganic pigment ultrafine particles are changed from a sol to a dry gel. Since the primer layer in the present invention is formed through the drying step, the conductive inorganic pigment ultrafine particles are in a fixed state, the strength is high, and the antistatic performance may be stable. Since the thermal transfer sheet of the present invention has the above-mentioned primer layer, it can also exhibit stable antistatic performance that does not depend on environmental changes.
In the present specification, the coating amount after drying of each coating liquid is determined by analyzing the mass of each sheet before applying the coating liquid to be measured and after coating and drying the analytical liquid (AUX220, Shimadzu). (Manufactured by Seisakusho Co., Ltd.) and obtained by dividing the mass difference by the area of the coated part.

(Heat resistant slipping layer)
The heat-resistant slipping layer in the present invention is formed using a thermoplastic resin on the primer layer for the purpose of improving heat resistance and running performance of the thermal head during printing.
Examples of the thermoplastic resin include polyester resins; polyacrylate resins; polyvinyl acetate resins; styrene acrylate resins; polyurethane resins; polyolefin resins such as polyethylene resins and polypropylene resins; polystyrene resins; Polyvinyl chloride resins; Polyether resins; Polyamide resins; Polyimide resins; Polyamide imide resins; Polycarbonate resins; Polyacrylamide resins; Polyvinyl chloride resins; Polyvinyl acetal resins such as polyvinyl butyral resins and polyvinyl acetoacetal resins; And the like, and silicone modified products thereof are preferable, and polyamideimide resins or silicone modified products thereof are more preferable in terms of heat resistance.

In addition to the thermoplastic resin, the heat-resistant slip layer is a thermal release agent such as wax, higher fatty acid amide, ester, metal soap, silicone oil, surfactant, etc .; Various additives such as organic powder; inorganic particles such as silica, clay, talc, calcium carbonate; and the like may be blended.

The heat resistant slipping layer can be formed by preparing a heat resistant slipping layer coating solution, applying the coating solution, and drying.
The coating solution for the heat resistant slipping layer may be composed only of the thermoplastic resin and the solvent, or may be added with additives to be blended as desired in addition to the thermoplastic resin and the solvent. It may be a thing.
As said solvent, the thing similar to the solvent quoted by the above-mentioned dye layer coating liquid is mentioned.
In the coating solution for heat resistant slipping layer, the solid content concentration can be appropriately selected according to the kind of the thermoplastic resin to be used, but is generally 5 to 30% by mass.

Dried coated amount of the heat-resistant lubricating layer, in that the thermal transfer sheet having excellent heat resistance is obtained, it is preferable to 2 g / m ² or less, and more preferably at 0.1 to 1 g / m ² .

Since the thermal transfer sheet of the present invention has the primer layer formed using the conductive colloidal inorganic pigment ultrafine particles as described above, it is excellent in antistatic properties.
The thermal transfer sheet of the present invention is usually in the range of 1.0 × 10 ^{4 to} 1.0 × 10 ¹¹ Ω / □ in an environment where the surface resistivity on the heat resistant slipping layer side is 23 ° C. and the relative humidity is 60%. Is in. The surface resistivity can be preferably 1.0 × 10 ¹⁰ Ω / □ or less, and may be 1.0 × 10 ⁷ Ω / □ or more within the above range. It may be 0 × 10 ⁸ Ω / □ or more.
In the present specification, the surface resistivity is measured with a surface resistance measuring instrument (Hiresta IP MCP-HT250, manufactured by Dia Instruments) in an environment of a temperature of 23 ° C. and a relative humidity of 60% in accordance with JIS K 6911. The value measured for the heat-resistant slipping layer surface after 10 seconds from the start of application.

(Other layers)
The thermal transfer sheet of the present invention may be one in which a transfer protective layer is further formed in the surface sequential order with the above-mentioned thermal transfer color material layer so that a protective layer for protecting the image surface can be transferred after image formation.
The configuration and formation of the transfer protective layer are not particularly limited, and can be selected from conventionally known techniques depending on the characteristics of the base sheet, the dye layer, and the like to be used.
When the base film is not releasable, the transfer protective layer is preferably provided with a release layer between the base film and the transfer protective layer to improve the transfer property of the transfer protective layer.

In the thermal transfer using the thermal transfer sheet of the present invention, the thermal transfer colorant layer is formed by superimposing the thermal transfer sheet on the surface of a transfer target that forms an image such as a thermal transfer image receiving sheet and applying thermal energy corresponding to the desired image. The dye can be transferred to the transfer medium.
The means for applying thermal energy may be any known means, and the amount of thermal energy to be applied can be adjusted by controlling the recording time with a recording apparatus such as a thermal transfer printer. .
Since the thermal transfer sheet of the present invention is excellent in heat resistance, troubles during printing such as printing wrinkles do not occur even when printing is performed by applying thermal energy of, for example, about 100 mJ / mm ² , and running performance of the thermal head. Also good.

Since the thermal transfer sheet of the present invention has the above-described configuration, it has excellent adhesion between the primer layer, the base sheet and the heat-resistant slip layer, has good heat resistance, and does not easily cause troubles during printing.
Since the primer layer can be formed by a coating technique such as a sol-gel method without using a binder resin, the thermal transfer sheet of the present invention can be produced at a low production cost.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and Comparative Examples.
In the text, “part” or “%” is based on mass unless otherwise specified.

Example 1
On the base material sheet (polyethylene terephthalate [PET] film, manufactured by Toray Industries, Inc., thickness: 4.5 μm), the primer layer coating solution 1 having the following composition is dried to have a coating amount of 0.2 g / m ^2. Was applied by gravure coating and dried by exposure to hot air at 110 ° C. for 1 minute to form a primer layer.
Next, on the primer layer, a coating solution for heat-resistant slipping layer having the following composition is applied by gravure coating so that the coating amount becomes 0.5 g / m ² after drying, and dried at 100 ° C. for 1 minute. Thus, a heat-resistant slip layer was formed.
Further, on the surface of the base sheet opposite to the heat-resistant slip layer, a coating solution for the dye layer having the following composition was applied by gravure coating so that the coating amount after drying was 0.7 g / m ^2. And dried at 80 ° C. for 1 minute to obtain a thermal transfer sheet 1.

<Primer layer coating solution 1>
・ Alumina sol (alumina sol 100, average particle size 10 to 20 nm, hydrochloric acid stable type, manufactured by Nissan Chemical Industries, Ltd.) 50.0 parts ・ Water 25.0 parts ・ Isopropyl alcohol 25.0 parts <Coating liquid for heat resistant slipping layer>
-Polyamideimide resin (HR-15ET, manufactured by Toyobo Co., Ltd.) 50.0 parts-Polyamideimide silicone resin (HR-14ET, manufactured by Toyobo Co., Ltd.) 50.0 parts-Zinc stearyl phosphate (LBT-1830 refining, Sakai Chemical Co., Ltd.) 10.0 parts ・ Zinc stearate (GF-200, manufactured by NOF Corporation) 10.0 parts ・ Polyester resin (Byron 220, manufactured by Toyobo Co., Ltd.) 3.0 parts ・ Inorganic filler (talc, average particle size 4) .2 μm) 10.0 parts

<Coating liquid for dye layer>
・ Anthraquinone dye (CI Solvent Blue 63) 3.0 parts ・ Polyvinyl butyral resin (ESREC BX-1, manufactured by Sekisui Chemical Co., Ltd.) 3.0 parts ・ Methyl ethyl ketone 45.5 parts ・ Toluene 45.5 parts

Example 2
A thermal transfer sheet 2 was produced in the same manner as in Example 1 except that the primer layer was formed using the primer layer coating solution 2 having the following composition.
<Primer layer coating solution 2>
Alumina sol (alumina sol 200, average particle size 10-20 nm, acetic acid stable type, manufactured by Nissan Chemical Industries, Ltd.) 50.0 parts ・ Water 25.0 parts ・ Isopropyl alcohol 25.0 parts

Comparative Example 1
A thermal transfer sheet 3 was produced in the same manner as in Example 1 except that the primer layer was formed using the primer layer coating solution 3 having the following composition.

<Primer layer coating solution 3>
・ Sulfonated polyaniline (manufactured by Nitto Chemical Co., Ltd.) 0.25 part ・ Water-based polyester (Polyester WR-961, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 4.75 parts ・ Phosphate ester surfactant (Plysurf 217E, No. 1) Ichikogaku Pharmaceutical Co., Ltd.)
0.20 parts, water 44.8 parts, isopropyl alcohol 50.0 parts

Comparative Example 2
A thermal transfer sheet 4 was produced in the same manner as in Example 1 except that the primer layer was formed using the primer layer coating solution 4 having the following composition.
<Primer layer coating solution 4>
・ Sulfonated polyaniline (manufactured by Nitto Chemical Co., Ltd.) 0.6 part ・ Polyvinylpyrrolidone resin (K-15, produced by ISP) 6.0 part ・ Water 46.7 parts ・ Isopropyl alcohol 46.7 parts

Test Examples The following tests were conducted on the thermal transfer sheets obtained from each Example and each Comparative Example.
1. Adhesiveness Each thermal transfer sheet was examined for adhesiveness on the heat resistant slipping layer side by a peel test using an adhesive tape. As the adhesive tape, a commercially available mending tape (size: length 200 mm × width 12 mm, manufactured by Nichiban Co., Ltd.) was used.
The evaluation criteria are as follows.
○: The heat-resistant slip layer did not peel from the substrate.
(Triangle | delta): The heat resistant slipping layer peeled partially from the base material (30% or less of a test area).
X: The heat resistant slipping layer was completely peeled from the substrate.

2. In accordance with JIS K 6911, the surface resistivity was measured at a temperature of 23 ° C. and a relative humidity of 60% with a surface resistance measuring instrument (Hiresta IP MCP-HT250, manufactured by Dia Instruments) 10 seconds after the start of application. It is the value measured about the heat resistant slipping layer surface.

3. Using a printing wrinkle sublimation printer (product name CP8000D, manufactured by Mitsubishi Electric Corporation), a solid image is printed on a roll paper for L size (89 x 127 mm), and the number of wrinkles generated per screen of the thermal transfer sheet is visually confirmed. did.
The evaluation criteria are as follows.
○: No wrinkle △: 1 to 3 wrinkles ×: More than 3 wrinkles

4). 2. Heat loss of primer layer The surface of the heat-resistant slip layer after printing was evaluated under the printing conditions described above, and it was visually confirmed whether the primer layer was rubbed off by heat. When the primer layer is rubbed off, the heat-resistant slipping layer on the layer is also rubbed off due to the primer layer being rubbed off.
The evaluation criteria are as follows.
○: The primer layer was not rubbed off.
X: The primer layer was scraped off.

The evaluation results are shown in Table 1.

It was found that the thermal transfer sheets 1 and 2 having a primer layer made of alumina sol are excellent in both adhesion and heat resistance in addition to antistatic properties.
On the other hand, the thermal transfer sheet 3 having a primer layer made of a sulfonated polyaniline and a polyester resin has a primer layer made of a sulfonated polyaniline and a polyvinyl pyrrolidone resin. It was found that the thermal transfer sheet 4 did not lose heat in the primer layer, but caused printing wrinkles.

Since the thermal transfer sheet of the present invention has the above-described configuration, it has excellent adhesion between the primer layer, the base sheet and the heat-resistant slip layer, has good heat resistance, and does not easily cause troubles during printing.
Since the primer layer can be formed by a coating technique such as a sol-gel method without using a binder resin, the thermal transfer sheet of the present invention can be produced at a low production cost.

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

Explanation of symbols

1. 1. Base sheet 2. 2. Thermal transfer color material layer Primer layer 4. Heat-resistant slip layer

Claims (2)

In the thermal transfer sheet provided with a heat transferable color material layer on one side of the base sheet and a heat resistant slipping layer provided on the other side of the base sheet via a primer layer,
A thermal transfer sheet, wherein the primer layer is formed using ultrafine particles of conductive colloidal inorganic pigment. The thermal transfer sheet according to claim 1, wherein the conductive colloidal inorganic pigment ultrafine particles are alumina sol.

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