JPH10297125A - Thermal-transfer recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer recording medium having neither uneven density nor blur in printing. SOLUTION: This recording medium is so constituted as to have at least a thermal transferring ink layer on one side of a support and have a heat resistant lubricating layer on the other side of the support. In this case, the surface roughness (the center-line mean roughness Ra) the thermal transfer ink layer is set to be 50 nm<=Ra<=400 nm. Further, the glossiness according to JISZ-8741 of the surface of the thermal transfer ink layer is set to be 5-80%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording medium in which a heat transferable ink layer is provided on one side of a support and a heat resistant lubricating layer is provided on the other side.

[0002]

2. Description of the Related Art Conventionally, a thermal transfer recording medium having a heat transferable ink layer provided on one surface of a support such as polyethylene terephthalate is heated from the back of the support by a thermal head to transfer the heat fusible ink layer. Thus, a thermal transfer recording method for forming a printed image on a receptor is widely used. For example, `` having an ink material composed of a coloring material and a binder material whose viscosity is reduced by increasing the temperature to impart transferability to a recording medium, and having a melting point or a pour point higher than that of the binder material; A heat transfer layer in which ink transfer auxiliary particles having a particle size equal to or larger than the thickness of the layer made of the ink material are mixed with the ink material, and the heat transfer layer is provided on one surface of a sheet-shaped heat-resistant substrate. Thermal transfer recording sheet "(Japanese Patent Publication No. 6-62017).
`` In a thermal transfer recording medium having a coating layer including at least one heat-fusible ink layer formed on a substrate, an average particle diameter larger than the average coating thickness is set in the uppermost layer of the coating layer. (Japanese Patent Application Laid-Open No. 6-15971), and "a thermal transfer recording medium comprising a support having at least a thermal transfer layer on one side thereof," The surface of the body where the thermal transfer layer is not formed and the surface of the thermal transfer layer,
A thermal transfer recording medium having a center line average roughness of 0.5 to 2.0 μm. (July 7-198
No. 15).

[0003]

SUMMARY OF THE INVENTION The above-mentioned thermal transfer recording medium is intended to prevent the occurrence of blurred or missing prints after transfer when paper having poor surface smoothness, such as plain paper, is used as an object to be transferred. But it is still inadequate. For example, those described in Japanese Patent Publication No. 6-62017 and JP-A-6-15971 can improve the printing on rough surface paper by adding irregularities to the surface by adding inorganic and organic fine particles to the heat transferable ink layer. However, there is a lot of variation and it cannot be said that it is at a sufficient level. Further, only the particle diameter of the additive is specified, but the actual roughness of the heat transferable ink layer is not specified. further,
In Japanese Patent Publication No. 7-19815, the center line average roughness Ra of both the thermal transferable ink layer and the back surface is 500 to 500.
Attempts have been made to improve the background smear in printing on rough surface paper by setting the thickness to 2000 nm (0.5 to 2.0 μm). With such a large surface roughness, the dispersion of the film thickness becomes relatively large, so that the thermal responsiveness is varied, and there is a problem that shading or blurring of printing occurs. As a thermal transfer recording medium that performs good printing on such rough paper, a thermal transfer ink layer is provided on a support, and a top coat layer mainly composed of a resin is provided thereon,
A method of improving the adhesiveness with the transfer receiving body by making the heat transferable ink layer itself mainly a resin having adhesiveness and improving the printing has been studied. Another problem arises that storage characteristics deteriorate.

[0004]

Means for Solving the Problems In order to solve the above problems, the present inventors have made intensive studies and found that the surface roughness (center line average roughness: Ra) of the heat transferable ink layer was 50 nm ≦ Ra ≦.
It has been found that the above problem can be solved by setting the thickness to 400 nm, and the surface roughness almost corresponds to 5% to 80% in glossiness according to JISZ-8741. Finds a solution,
The present invention has been reached. That is, the present invention provides (1)
In a thermal transfer recording medium having at least a heat-sensitive transferable ink layer on one surface of a support and a heat-resistant lubricating layer on the other surface of the support, the surface roughness (center line average roughness) of the heat transferable ink layer (2) a thermal transfer recording medium characterized in that Ra) satisfies 50 nm ≦ Ra ≦ 400 nm, and (2) having at least a thermal transferable ink layer on one surface of a support and heat resistance on the other surface of the support. In a thermal transfer recording medium having a lubricating layer, JISZ-874 on the surface of the thermal transferable ink layer
1. A thermal transfer recording medium, wherein the glossiness according to No. 1 is 5% or more and 80% or less. The present invention will be described in detail below. The present invention is applied to a thermal transfer recording medium having at least a heat-sensitive transferable ink layer on one surface of a support and a heat-resistant lubricating layer on the other surface. FIG. 1 shows an example of such a configuration. In the thermal transfer recording medium shown in FIG.
The heat transferable ink layer 2 is provided on one surface of the support 1, and the heat-resistant lubricating layer 3 is provided on the other surface.
The thermal transferable ink layer 2 may be a single layer or a multilayer of two or more layers as necessary. FIG. 1B shows an undercoat layer 4 between the heat transferable ink layer 2 and the support 1.
1 shows a configuration of a thermal transfer recording medium provided with. <Composition Components of Melt Transfer Type Ink Layer> The melt transfer type ink layer is composed of a colorant and a binder, and is softened and melted by heating to transfer to a transfer target. Pigments such as carbon black and various dyes can be used as the colorant. These pigments and dyes may be used alone or in combination of two or more. Further, the color tone may be adjusted by mixing an extender or a white pigment. Further, the surface of the colorant may be treated with a surfactant, a silane coupling agent or the like in order to improve the dispersibility in the binder. The particle size of the colorant is 5 to 1000 nm, preferably 10 to 800 nm.
nm is desirable. If it is smaller than 5 nm, the dispersibility is poor and the viscosity is high. If it is larger than 1000 nm, the color tone as a colorant is inferior. The addition amount is 3 to 90% by weight, preferably 5 to 85% by weight in the thermal transfer ink layer. When the amount is less than 3% by weight, the transfer density becomes insufficient.
If the amount is more than 0% by weight, the amount of the fusible binder is small, so that the transfer becomes difficult and the transfer density becomes insufficient. In addition, it causes soiling due to lack of the coating film. As the binder, waxes or thermoplastic resins commonly used for the melt transfer type ink layer can be used without any particular limitation. As the waxes, carnauba wax, candelilla wax, montan wax, microcrystalline wax, paraffin wax, wood wax, synthetic fat wax and the like can be used according to various uses. As thermoplastic resins, polyamide resins, acrylic resins, styrene-acrylic resins, polyester resins,
Known resins such as a rosin resin and an ethylene-vinyl acetate resin can be used. The binder is preferably contained in an amount of 50 to 500 parts by weight based on 100 parts by weight of the colorant. If necessary, inorganic or organic fine particles can be added as additives. For example, silica, talc, alumina, silicon dioxide, chromium oxide, calcium carbonate, inorganic fine particles such as barium sulfate, polyester,
Organic fine particles such as polyethylene, polypropylene, and melamine resin are used, but are not limited thereto, and may be a mixture of two or more kinds. The particle size of the additive is 0.1 to 15 μm, preferably 0.2 to 10 μm.
μm is good. No effect can be obtained if it is smaller than 0.1 μm,
On the other hand, if it is larger than 15 μm, swelling or longitudinal streaks will occur at the time of coating, which will lower the yield. The amount of addition is preferably 1 to 50 parts by weight, more preferably 2 to 40 parts by weight, per 100 parts by weight of the coloring agent. If the amount is less than 1 part by weight, no effect is obtained. If the amount is more than 50 parts by weight, the amount of the colorant decreases, and the printing quality deteriorates. The coating composition for forming a thermal transfer ink layer in the present invention is prepared by adding an organic solvent to each of the above components. There is no particular limitation on the solvent used for preparing the coating material, and it may be appropriately selected in consideration of the solubility, compatibility, dispersion stability, drying efficiency, etc. of the binder.Examples include ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. , Toluene, xylene and other aromatic hydrocarbons, ethyl acetate, butyl acetate and other esters, alcohols such as isopropanol and butanol, dioxane, tetrahydrofuran, dimethylformamide, hexane, chlorine-substituted hydrocarbons and other diluents or solvents Is preferably used as a single solvent or a mixed solvent obtained by mixing these at an arbitrary ratio. These organic solvents are 100%
It is not necessary to be pure, and impurities such as isomers, unreacted products, by-products, decomposition products, oxides, and moisture may be contained in addition to the main component. These impurities are preferably 5% by weight. %, More preferably 3% by weight or less. If the amount of impurities is large, the dispersibility of the paint, the storage stability of the paint, and the storage characteristics of the medium are adversely affected. These organic solvents are used in a non-volatile manner as a solvent in the entire coating so that the viscosity of the coating becomes 5 to ¹⁰⁰ cp at a shear rate of 3000 sec- ¹ by a cone plate type or double cylinder type viscometer at the stage of application. The solvent may be used so as to have a partial concentration of 1 to 45% by weight, preferably about 5 to 40% by weight. It is preferable that the viscosity is appropriately determined in consideration of the size, the dilution stability of the paint, and the like so as to be within the above viscosity range. The ink layer paint is prepared by mixing the above-mentioned materials and an organic solvent and subjecting them to a dispersion treatment as required. There is no particular limitation on the method of mixing or dispersing, hibar, ball mill, attritor,
A mixing and dispersing machine such as a sand mill can be used arbitrarily. Further, the adjustment of the degree of dispersion can be arbitrarily set by changing the type of disperser and the dispersion time. In addition, the organic solvent addition operation can be performed stepwise in each step of the paint production, and the flow rate is regulated and sequentially added to the tank while stirring, or an operation of gradually mixing the paint with the pipe is performed. You can do it too. And if possible, it is more preferable to perform filtration. By performing these operations, the stability of the coating material is improved, and the generation of aggregates and foreign substances can be suppressed. The thickness of the thermal transfer ink layer can be determined in consideration of the required transfer characteristics,
The preferred range is 0.1 to 10.0 μm, and more preferably 0.3 to 5.0 μm. The surface roughness (center line average roughness: Ra) of such a heat transferable ink layer is 50 n.
m ≦ Ra ≦ 400 nm, preferably 55 nm ≦ Ra ≦ 4
00 nm, more preferably 60 nm ≦ Ra ≦ 400 n
m. If the surface roughness of the ink layer is less than 50 nm, the surface of the ink layer becomes too smooth, causing blocking with the heat-resistant lubricating layer during storage. In addition, printing on plain paper is also unclear because the contact area between the ink and the paper is small, causing blurring or missing. On the other hand, when the surface roughness exceeds 400 nm, the thermal responsiveness greatly varies due to the large variation in the film thickness as described above, which causes a problem that print density and blurring occur. For the same reason, the glossiness of the ink surface is 5% to 80%, preferably 5% to
70%, more preferably 5% to 60%. The surface roughness and glossiness of the ink layer can be arbitrarily set by controlling the type, particle size, dispersion method or drying temperature of the ink layer paint of the color pigment. Regarding the type and the particle size of the color pigment, some types of the color pigment cause strong and weak aggregation of the particles, and the particle size varies. In general, in the case of the same particle diameter, particles having weak aggregation of particles are easy to disperse in the paint, so that the surface roughness of the ink layer is small and the glossiness can be set high. On the other hand, those having strong aggregation have the opposite tendency. In addition, when the cohesive strengths are the same, if the particles having a small particle diameter are used, the surface roughness of the ink layer can be reduced and the glossiness can be increased, and if the particles having a large particle diameter are used, the opposite tendency is caused. Regarding the dispersing method, the dispersing force varies depending on the type of dispersing machine (the hyper, the ball mill, etc.). However, for example, by increasing the dispersing time in each dispersing machine, the degree of dispersion increases and the ink surface roughness decreases. Glossiness can be increased. If the dispersion time is shortened, the tendency is reversed. With respect to the drying temperature, when the drying temperature is increased, the heat-melted components in the ink layer coating film are melted or fused, and as a result, an ink layer having small surface roughness and high gloss can be obtained. Conversely, when the drying temperature is lowered, the above-mentioned melting and fusion hardly occur, so that the surface roughness is large and the glossiness is low. Therefore, by adjusting these, it is possible to adjust the desired surface roughness and glossiness of the ink layer. <Undercoat layer composition component> The undercoat layer plays a role of adjusting the adhesive force between the melt transfer type ink layer and the support in the present invention, that is, the releasability of the thermal transfer ink layer by heating from the back of the support with a thermal head. Play a role in enhancing Waxes or thermoplastic resins can be used for the undercoat layer without any particular limitation. As the waxes, carnauba wax, candelilla wax, montan wax, microcrystalline wax, paraffin wax, wood wax, synthetic fat wax and the like can be used according to various uses. As the thermoplastic resins, known resins such as polyamide resins, acrylic resins, styrene-acrylic resins, polyester resins, rosin resins, and ethylene-vinyl acetate resins can be used. If necessary, a coloring pigment or a coloring dye can also be used. The paint for forming an undercoat layer in the present invention is prepared by adding an organic solvent and / or water to each of the above components. There is no particular limitation on the organic solvent used for preparing the coating material, and it may be appropriately selected in consideration of the solubility, compatibility, drying efficiency, and the like of waxes or resins, for example, ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. , Toluene, xylene and other aromatic hydrocarbons, ethyl acetate, butyl acetate and other esters, isopropanol, butanol and other alcohols, dioxane, tetrahydrofuran, dimethylformamide, hexane, chlorine-substituted hydrocarbons and other diluents. It is preferable to use the solvent as a single solvent or a mixed solvent obtained by mixing these at an arbitrary ratio. The thickness of the undercoat layer is 0.1 to 3.0 μm, preferably 0.1 to 3.0 μm.
It is in the range of 3 to 2.5 μm, more preferably 0.5 to 2.0 μm. If the thickness is less than 0.1 μm, the effect of the undercoat layer does not appear, and if it exceeds 3.0 μm, the effect is saturated. <Heat-resistant lubricating layer composition component> The heat-resistant lubricating layer is generally made of a heat-resistant material such as a silicone resin, a melamine resin, an epoxy resin, a phenol resin, a fluororesin, a polyamide resin, a polyimide resin, a polyamideimide resin, a polyacetal resin, and a polyacetal resin. Resin is used. In addition, silicone oil,
Lubricants such as higher fatty acids, higher fatty acid esters, various surfactants, and fluorine compounds, or melamine resin particles, silicone resin particles, and the like may be blended. The heat-resistant lubricating layer can be formed by applying and drying a material obtained by dissolving and dispersing a curing agent and other compounding agents in an appropriate solvent as required in addition to the heat-resistant resin and the lubricant. The thickness of the heat-resistant lubricating layer is in the range of 0.01 to 0.5 μm, preferably 0.01 to 0.5 μm.
The range is preferably from 0.3 to 0.3 μm. If it is less than 0.01 μm, the heat resistance is insufficient, and if it exceeds 0.5 μm, the coating film is shaved and the shaved powder adheres to the thermal head. <Support> Supports include, for example, paper sheets such as plain paper, condenser paper, laminated paper and coated paper, polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefins, polyamides, Known films such as polyimide, polyamide imide, polysulfone cellulose triacetate, and polycarbonate can be used, and among these, PET, PEN, and aromatic polyamide are preferable. The thickness of the support is preferably 0.5 to 10.0 μm. If it is less than 0.5 μm, the strength of the thermal transfer recording medium is insufficient, and if it exceeds 10.0 μm, heat conduction from the thermal head deteriorates and thermal transfer characteristics deteriorate. <Coating method> There is no particular limitation on the method of applying the paint prepared as described above to the support, and wire bar coating,
Any of reverse coating, gravure coating or extrusion nozzle coating may be used. Among them, extrusion nozzle coating is most preferable. For example, when forming a multi-layer coating film including a thermal transferable ink layer,
A so-called wet-on-wet coating method in which an undercoat layer and a thermal transfer ink layer are applied in a wet state on a support, or a so-called wet-on-wet method in which an undercoat layer is applied and dried followed by application of a thermal transfer ink layer. Any of the dry coating methods and the like can be used. The heat-resistant lubricating layer may be applied before or after the undercoat layer and the thermal transfer ink layer are applied, or may be applied simultaneously. The support conveyance speed is 50 to 700 m /
A range of minutes is preferred. Each coating is dried in a drying oven.
The drying temperature is 25-100 ° C, preferably 25-90.
C., more preferably in the range of 25 to 80 C. When the temperature is lower than 25 ° C., drying becomes insufficient, and particularly in the case of an ink layer, the surface roughness becomes too large and the surface gloss is lowered, which causes the occurrence of shading and blurring of the print. 10
If the temperature exceeds 0 ° C., melting of the molten component in the coating film, fusion occurs, the surface roughness of the ink layer becomes too small, and the gloss of the surface becomes too high, and the blocking with the heat-resistant lubricating layer deteriorates, The transfer characteristics of printing deteriorate. Further, a temperature gradient may be provided in the drying furnace, and general air or an inert gas may be used as a gas atmosphere in the drying furnace.

[0005]

EXAMPLES The present invention will be described more specifically with reference to examples, but it goes without saying that the present invention is not limited to these examples. Example 1 <Thermal Transferable Ink Layer Coating> The following formulation was charged into a ball mill and dispersed for 24 hours to prepare a heat transferable ink layer forming coating. Carbon black (Mitsubishi Chemical Corporation: # 25B) 100 parts by weight Carnauba wax (Ceralica NODA) 20 parts by weight Paraffin wax (Nippon Seiwa Co., Ltd .: HNP-9) 50 parts by weight Ethylene vinyl acetate copolymer (Sumitomo) KF-11) 130 parts by weight Toluene 860 parts by weight Methyl ethyl ketone 340 parts by weight A 95% cut filtration accuracy of the obtained paint is 15.0 μm.
Circulating filtration was performed using a depth filter. <Undercoat layer coating composition> The following components were charged into a hypermixer and mixed and stirred for 1 hour to prepare an undercoat layer forming coating composition. Water-based wax emulsion (manufactured by Konishi Corporation: WE, solid content concentration = 40 wt%) 50 parts by weight Isopropyl alcohol 50 parts by weight A 95% cut filtration accuracy of the obtained paint is 15.0 μm.
Circulating filtration was performed using a depth filter. <Heat-resistant lubricating layer paint> The following components were charged into a hypermixer and mixed and stirred for 1 hour to prepare a heat-resistant lubricating layer forming paint. Polyamideimide resin (manufactured by Toyobo Co., Ltd .: HR-14ET) 1 part by weight Silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd .: KF-860) 0.07 part by weight Ethanol 50 parts by weight Toluene 50 parts by weight The obtained paint is 95% Circulation filtration was performed using a depth filter having a cut filtration accuracy of 5.0 μm. <Preparation of thermal transfer recording medium> A 3.5 μm polyethylene terephthalate support (K5, manufactured by Diafoil Hoechst)
80-3.5 W) on one side of the surface of the undercoat layer is coated with a paint for forming an undercoat layer and dried to form an undercoat layer coating film having a thickness of 0.8 μm. The coating material for forming a layer was applied and dried to form a coating film having a thickness of 0.1 μm. After applying the above-mentioned coating composition for forming a thermal transfer ink layer on the undercoat layer, the coating is dried at 25 ° C. to obtain a film thickness = 1.8 μm.
After forming a coating film of m, the coated raw roll was cut into a 1/4 inch width to obtain a thermal transfer recording medium (ink ribbon) for word processing. Table 1 shows the surface roughness, glossiness, and characteristics of the thermal transfer ink layer of the obtained thermal transfer recording medium. Examples 2 to 8 and Comparative Examples 1 to 3 Thermal transfer recording media were obtained in the same manner as in Example 1 except that the drying temperature was changed. Table 1 shows the surface roughness, glossiness, and characteristics of the thermal transfer ink layer of the obtained thermal transfer recording medium. Examples 9 to 14 and Comparative Examples 4 to 6 Thermal transfer recording media were obtained in the same manner as in Example 1 except that the drying temperature was set to 50 ° C. and the dispersion time was changed. Table 2 shows the surface roughness, glossiness, and characteristics of the heat transferable ink layer of the obtained heat transfer recording medium. The characteristics of the thermal transfer recording medium were evaluated by the following evaluation methods. <Surface Roughness (Center Line Average Roughness: Ra)> Using a three-dimensional surface roughness meter (Kosaka Laboratories: ET-30HK), JIS
It was measured under the following conditions in accordance with B-0601. Weight: 6 mg Magnification factor: 10,000 times Speed: 100 μm / sec <Ink layer surface glossiness> Using a coated 1/4 inch width raw material, a gloss meter GM- manufactured by Murakami Color Research Laboratory Co., Ltd.
The glossiness of the ink surface was measured by 3D (incident angle was 60
゜). The measurement conditions are the methods described in JISZ-8741. <Word processing printing quality> Using the above samples, printing evaluation was performed on plain paper using a word processor WD-C500 manufactured by Sharp Corporation, and ranking was performed according to the following criteria. Printing density: 7 Printing speed: High speed Scratches and missing ：: No blurring or missing of printing is observed at all. ：: Fuzziness or omission of printing is hardly recognized. Δ: Scattering or omission of printing is partially observed. ×: Scattering or omission of printing is observed on the entire surface. <Blocking> With the thermal transfer recording medium wound up,
After standing for 24 hours in an environment of 40 ° C. and 80% RH, blocking evaluation between the heat transferable ink layer and the heat-resistant lubricating layer was performed according to the following criteria. ：: No sticking between the thermal transfer ink layer and the heat-resistant lubricating layer. X: NG state because the heat transferable ink layer and the heat-resistant lubricating layer were stuck.

[0006]

[Table 1]

[0007] As shown in Table 1, the embodiment is superior in both the print blurring property and the blocking property.

[0008]

[Table 2]

As shown in Table 2 above, the embodiment is superior in both the print blurring property and the blocking property.

[0010]

According to the present invention, a thermal transfer recording medium having excellent storability and capable of excellent printing on plain paper can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a thermal transfer recording medium, in which (a) has no undercoat layer and (b) has an undercoat layer.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Hiroshi Nakajima 1-1-13 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation

Claims (2)

[Claims] In a thermal transfer recording medium having at least a thermal transferable ink layer on one surface of a support and a heat-resistant lubricating layer on the other surface of the support, the surface roughness of the thermal transferable ink layer ( Center line average roughness: Ra) 50 nm ≦ Ra ≦ 4
A thermal transfer recording medium having a thickness of 00 nm. 2. In a thermal transfer recording medium having at least a thermal transferable ink layer on one surface of a support and a heat-resistant lubricating layer on the other surface of the support, the JISZ-8741 of the surface of the thermal transferable ink layer may be used. A thermal transfer recording medium having a glossiness of 5% or more and 80% or less.