JPH0615971A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To perform printing excellent in heat-resistant storage stability and good in high speed followability, in a thermal transfer recording medium constituted by forming a coating layer containing at least one hot-melt ink layer on a base material, by adding fine particles having an average particle size larger than the average coating thickness of the coating layer to the uppermost layer of the coating layer. CONSTITUTION:In a thermal transfer recording medium wherein a coating layer containing at least one hot-melt ink layer 2 is formed on a base material 4, inorg. or org. fine particles 1 having an average particle size r1 larger than the average coating thickness alpha of the coating layer are added to the uppermost layer of the coating layer. As a result, printing excellent in heat-resistant storage stability, good in the resolving power to rough surface paper and improved in high speed followability can be performed.

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 used in a thermal transfer recording apparatus such as a printer or a facsimile, and more particularly to a thermal transfer recording medium satisfying heat resistant storage stability, high speed followability and high printing quality. .

[0002]

2. Description of the Related Art In a thermal transfer recording system, a thermal transfer recording medium is used in which at least one layer of thermal melting ink is applied onto a base material on a sheet. Is a recording system in which the ink layer is heated and melted by a heating head from the base material side of the thermal transfer recording medium to obtain a transfer image on the transfer paper. According to this method, the device used is low in noise, excellent in operability and maintainability, and plain paper can be used as the transfer target paper, and thus has been widely used in recent years.

[0003]

However, as the performance of thermal transfer printers has been improved, complex functions such as high-speed printing on rough surface paper have been required. When considering the speedup of the printer, high-speed followability (higher sensitivity) of the ribbon becomes a major issue. In order to improve high-speed followability while maintaining the coating of rough surface paper, conventionally, a resin component was introduced into the binder (Japanese Patent Laid-Open Nos. 54-87234 and 54-54234).
No. 163044, No. 56-98269, No. 62-130887), etc., but it is necessary to lower the softening start temperature of the ink to achieve higher sensitivity.

Conventionally, a mixture of waxes having a melting point in the temperature range of about 50 ° C. to about 150 ° C. and resins imparting adhesiveness and coating flexibility is used as a binder material for the hot-melt ink. Has been. When such a binder material is used, in order to obtain high-resolution printing on rough-surfaced paper even when printing speed is increased, the melting point of waxes, the glass transition temperature of resins, or resins It is conceivable that the melting start temperature is lowered by increasing the compounding ratio of (3) and further adding a third component having a low melting point.

On the other hand, the required characteristics of the thermal transfer recording medium are:
Storage stability at high temperature is mentioned. That is, it is exposed to a considerably high temperature under conditions such as transportation in summer.
Since the thermal transfer recording medium is generally provided in a roll shape, a considerable load is applied to the center of the roll. for that reason,
Even if the heat-fusible ink-coated surface of the base material does not exhibit adhesiveness at room temperature, it retains adhesiveness when stored at high temperature and high pressure, and is fused to the surface on the opposite side. The problem that there is resistance in the part that peels off when pulling out, or transfer occurs on the opposite side (blocking)
There is a need to solve this.

However, when the ink whose melting start temperature is lowered as described above is used, blocking occurs remarkably, which is not suitable for practical use, and further improvement is desired. Therefore, an object of the present invention is to provide a thermal transfer recording medium which is excellent in heat-resistant storage stability, has a good resolution (coating) on a rough surface paper, and is capable of high-speed followability printing.

[0007]

As a result of earnest studies, the inventors of the present invention have found that the average coating thickness of the uppermost layer or the coating thickness of the uppermost layer of the coating layer including the heat-meltable ink layer of the thermal transfer recording medium. It was confirmed that the above object can be achieved by containing fine particles having an average particle diameter larger than the average coating thickness of the entire layer, and the present invention has been completed.

That is, the present invention provides a thermal transfer recording medium comprising a base material and a coating layer containing at least one heat-fusible ink layer, and the average coating thickness in the uppermost layer of the coating layer. Thermal transfer recording medium characterized by containing inorganic or organic fine particles having a larger average particle diameter, and thermal transfer recording formed by forming a coating layer containing at least one heat-meltable ink layer on a substrate. In the medium,
The present invention provides a thermal transfer recording medium characterized in that the uppermost layer of the coating layer contains inorganic or organic fine particles having an average particle diameter larger than the average coating thickness of the entire coating layer.

For the thermal transfer recording medium of the present invention, a thermal melting ink having a high melting sensitivity and a low melting start temperature can be used.
From the top layer, the top layer contains inorganic or organic fine particles having a particle size larger than the average coating thickness of the uppermost layer of the surface on which the heat-meltable ink layer is formed or the average coating thickness of the entire coating layer. Since the fine particles are exposed, the fine particles can be wound around the roll in a state where the contact area between the heat-meltable ink and the surface on the opposite side of the substrate is small, and blocking does not occur even at high temperature storage.

An example of an embodiment of the thermal transfer recording medium of the present invention is shown in FIG. FIG. 1 shows a release layer 3 formed on a substrate 4.
And the heat-meltable ink layer 2 formed on the release layer 3, and the fine particles 1 are contained in the heat-meltable ink layer 2 which is the uppermost layer. Here, FIG.
The fine particles 1 therein are shown as circles for convenience, but the fine particles may have a spherical shape, an amorphous shape, or a mixture thereof. Here, since the average particle diameter r ₁ of the fine particles 1 is larger than the average coating thickness α of the heat-meltable ink layer 2 (r ₁ > α), the fine particles 1 are exposed from the uppermost heat-meltable ink layer 2. The roll can be wound in a state where the contact area between the heat-meltable ink layer and the back surface of the substrate is small.

An example of another embodiment of the thermal transfer recording medium of the present invention is shown in FIG. FIG. 2 also shows the release layer 3 formed on the substrate 4.
And the heat-meltable ink layer 2 formed on the release layer 3, and the fine particles 1 are contained in the heat-meltable ink layer 2 which is the uppermost layer. Here, the average particle diameter r ₂ of the fine particles 1 is larger than the sum of the average coating thickness α of the hot-melt ink layer 2 and the average coating thickness β of the release layer 3 (r ₂ > α + β), The fine particles are exposed from the uppermost heat-meltable ink layer.

An example of the method for measuring the average particle size of fine particles according to the present invention is shown, but the method is not limited to this method. <Measurement method of average particle size> 0.5 g of the sample is weighed in a 200 ml beaker, 150 ml of ion-exchanged water is added, and the mixture is ultrasonically dispersed for 1 minute while stirring. Next, electrolyte (ISTON II) 150ml
Then, the above dispersion liquid is dropped with a dropper and measured with a Coulter counter. Determine the average particle size from the measurement chart.

Inorganic or organic fine particles are generally added to the hot melt ink. The average particle size of the inorganic or organic fine particles to be added to the heat-meltable ink in the present invention may be a single particle or a particle in which fine particles are condensed to newly form one particle. It is necessary that the particles are, on average, larger than the average coating thickness of the highest heat-meltable ink or the total average coating thickness of all coating layers.
This is because, with particles having a particle size smaller than these coating thicknesses, the number of particles exposed on the surface is small, and in order to maintain heat-resistant storage stability, more fine particles than are necessary when using particles with a large particle size. Need to be added. However, when the addition amount of the fine particles is large, the melt viscosity of the hot-melt ink increases, and the coating of the rough surface paper is reduced. That is, the larger the amount of the fine particles added, the higher the heat resistance stability, but if added in excess, the melt viscosity of the hot-melt ink increases and the print quality deteriorates. Therefore, it is desirable to control the addition amount of the fine particles to the minimum amount capable of ensuring the heat resistance stability. In the present invention, the amount of fine particles contained in the uppermost layer is 0.1 to 20% based on the weight of the uppermost layer of the coating layer, preferably 0.5 to 2
0%, more preferably 0.1 to 10% is desirable.

The fine particles which are an essential component of the thermal transfer recording medium of the present invention may be inorganic or organic, or may be a mixture of both. For example, as the inorganic substance, silicon dioxide such as quartz or hydrous silicic acid, metal oxide such as aluminum oxide, chromium oxide and iron oxide, metal such as manganese, iron and cobalt, fine powder such as carbon black and graphite is used, and as the organic substance, However, fine particles of plastics such as polyester, polyethylene, polypropylene, and silicone, and fine particles of a low-molecular-weight compound having a high melting point that are incompatible with the binder are used, but the present invention is not limited to these and may be a mixture of two or more kinds. May be.

In the present invention, it is preferable to use spherical particles as the fine particles. As described above, the relationship between the particle size of the fine particles and the average coating thickness of the coating layer greatly affects the heat resistant storage stability, but if the shape of the fine particles is spherical with no anisotropy, Since its particle diameter can be effectively utilized, good heat stability can be obtained with a small amount of addition.

As the binder material of the hot melt ink to which the above-mentioned fine particles are added, styrene, vinyltoluene, α-
Styrene and its derivatives such as methylstyrene, chlorostyrene, vinylbenzoic acid, sodium vinylbenzene sulfonate, aminostyrene, etc., homopolymers and copolymers of substitution products, methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-hydroxyethyl methacrylate. Methacrylic acid esters and methacrylic acid such as, methyl acrylate, acrylic acid esters such as 2-ethylhexyl acrylate and acrylic acid, dienes such as butadiene and isoprene, acrylonitrile, vinyl ethers, maleic acid and maleic acid esters, maleic anhydride, A vinyl monomer such as cinnamic acid or vinyl chloride may be used alone or as a copolymer with another monomer. Of course, also in the case of the vinyl-based resin, a polyfunctional monomer such as divinylbenzene may be used as a crosslinked polymer. Furthermore, polycarbonate, polyamide, polyester, polyurethane, silicone resin,
Fluorine resin, phenol resin, terpene resin, petroleum resin, hydrogenated petroleum resin, alkyd resin, ketone resin, cellulose derivative and the like may be used. When these polymers or oligomers are used in the form of a copolymer, the copolymer may be a random copolymer, an alternating copolymer, a block copolymer, an interpenetrating copolymer, depending on the required application. And the like can be appropriately selected and used. When two or more kinds of polymers and oligomers are mixed and used, in addition to mechanical mixing such as melt mixing, solution mixing, and emulsion mixing, co-polymerization at the time of polymerizing the polymer and oligomer components, and multi-stage polymerization method are used. May be.

If desired, waxes, oils and liquid plasticizers used in conventional heat-meltable inks may be added and mixed.

When the colorant is contained in a layer other than the uppermost layer, it may not be added to the uppermost layer, but when the layer other than the uppermost layer does not contain the colorant, it is necessary to add it to the uppermost layer. There is. As the colorant, for example, carbon black,
Black dyes and pigments such as oil black and graphite, CI Pigmen
t Yellow 1, 3, 74, 97, 98 acetoacetic acid arylamide monoazo yellow pigments (fast yellow), CI
Acetoacetic acid arylamide bisazo yellow dyes such as Pigment Yellow 12, 13 and 14 and CI Pigment Yellow 19 and 7
7, Yellow 79, Yellow pigments such as CI Disperse Yellow 164, CIPig
ment Red48, ibid 49: 1, ibid 53: 1, ibid 57: 1, ibid 81,
122, 5 and other red or red pigments, CISolvent Red
52, 58, 8 and other red pigments, CI Pigment Blue 15: 3
Copper phthalocyanine and its derivatives, and blue dyes and pigments such as modified products can be used. Furthermore, dyes and pigments well known in conventional printing inks and other coloring applications such as colored or colorless sublimable dyes can be used. These colorants may be used alone or in combination of two or more. Of course, the color tone may be adjusted by mixing with an extender pigment or a white pigment. Furthermore,
In order to improve the dispersibility in the binder material component, the surface of the colorant may be treated with a surfactant, a coupling agent such as a silane coupling agent, a polymer material, or a polymer dye or a polymer graft pigment may be used. Good.

The thermal transfer recording medium of the present invention is usually prepared by coating a base material with a hot-melt ink containing the above-mentioned fine particles, a binder resin and a colorant and, if necessary, the above-mentioned various additives, and applying at least one layer of thermal ink. It is manufactured by forming a meltable ink layer. The number of heat-meltable ink layers is 1
~ 2 layers are preferred. The total average coating thickness of the heat-fusible ink layer is preferably 1 to 5 μm.

Further, if a release layer is provided between the base material and the heat-meltable ink layer closest to the base material, a more sensitive thermal transfer recording medium can be obtained. The thickness of the release layer is not particularly limited,
0.3 to 3 μm is preferable. The release layer preferably contains waxes as a main component, and is used in conventional heat-meltable inks such as paraffin wax, microcrystalline wax, polyethylene wax, carnauba wax, candelilla wax, rice wax and montan wax. Various waxes are preferably used. These waxes may be used alone or in combination of two or more. Further, resins such as ethylene vinyl acetate copolymer and ethylene acrylic acid ester copolymer may be added if necessary.

Further, by providing the above-mentioned heat-meltable ink containing or not containing a coloring agent on the colored ink layer having a good thermal response formed on the substrate, the thermal transfer recording with higher sensitivity can be obtained. The medium is obtained. Further, if necessary, a heat resistant lubricating layer or the like can be formed on the surface opposite to the heat fusible ink layer.

In the production of the hot-melt ink according to the present invention, a solution or a dispersion emulsion is prepared in a solvent or a dispersion medium in which a binder material can be dissolved or stably dispersed, and a ball mill, sand mill, attritor, basket mill,
It can be prepared by a mixing and dispersing machine such as a triple roll. Alternatively, the colorant may be dispersed by the above method, and then the fine particles may be added and stirred and mixed with a homomixer, a disper, a dissolver or the like. Further, without using a solvent or the like, the mixture may be melt-mixed with a heating type three roll, a heating type kneader, a heating type sand mill, a heating type attritor or the like.

The hot-melt ink thus prepared is applied and printed on the substrate by a solution or melt coating method using a gravure coater, a wire bar or the like.

Further, the heat-meltable ink may be pulverized by a spray dry method, a pulverization method or the like, and then powder coated on the substrate by an electrostatic coating method or the like. In this case, after the powder coating, if necessary, heating, pressurization, solvent treatment, etc. may be performed to fix the heat-meltable ink on the base material for use.

[0025]

EXAMPLES The effectiveness of the present invention will be illustrated below with reference to Examples, but the present invention is not limited to these. In the examples, “parts” means “parts by weight” unless otherwise specified.

Examples 1 and 2 and Comparative Examples 1 to 3 A wax release layer of a PET (polyethylene terephthalate) film having a heat-resistant lubricating layer on one side and a wax release layer (average coating thickness 1.5 μm) on the other side. On each side, an ink film was prepared by applying an ink prepared with the following composition by a wire bar coater so that the average coating thickness was 2 μm.

(Example 1) 35 parts of ethylene vinyl acetate copolymer (41% by weight of vinyl acetate) [EVAFLEX 40Y, manufactured by Mitsui DuPont Polychemical Co., Ltd.] 15 parts of paraffin wax (melting point 75 ° C.) [HNP- 10, manufactured by Nippon Seiro Co., Ltd.] ・ Carnauba wax (melting point 84 ° C) 15 parts ・ Carbon black 35 parts ・ Silicon dioxide fine particles (average particle size 2.2 μm) 1 part [Mizukasil P-707, Mizusawa Chemical Industry Co., Ltd. Manufacturing] -Toluene 400 parts.

(Example 2) 40 parts ethylene vinyl acetate copolymer (28% by weight vinyl acetate) [EVAFLEX 220, manufactured by Mitsui DuPont Polychemical Co., Ltd.] 15 parts paraffin wax (melting point 75 ° C.) [HNP- 10, manufactured by Nippon Seiro Co., Ltd.] ・ Carnauba wax (melting point 84 ° C) 10 parts ・ Carbon black 35 parts ・ Silicon dioxide fine particles (average particle size 3.0 μm) 2 parts [Mizukasil P-78A, Mizusawa Chemical Industry Co., Ltd. Manufacturing] -Toluene 400 parts.

(Example 3) 35 parts of ethylene vinyl acetate copolymer (41% by weight of vinyl acetate) [EVAFLEX 40Y, manufactured by Mitsui DuPont Polychemical Co., Ltd.] 15 parts of paraffin wax (melting point 75 ° C.) [HNP- 10, manufactured by Nippon Seiro Co., Ltd.] ・ Carnauba wax (melting point 84 ° C) 15 parts ・ Carbon black 35 parts ・ Silicon resin spherical fine particles (average particle diameter 3.0 μm) 0.5 part [Tospearl 130, manufactured by Toshiba Silicone Co., Ltd.] -Toluene 400 parts.

(Comparative Example 1) -Ethylene vinyl acetate copolymer (41% by weight vinyl acetate) 15 parts [EVAFLEX 40Y, manufactured by Mitsui DuPont Polychemical Co., Ltd.]-Paraffin wax (melting point 75 ° C) 15 parts [HNP- 10, manufactured by Nippon Seiro Co., Ltd.]-Carnauba wax (melting point 84 ° C) 15 parts-Carbon black 35 parts-Toluene 400 parts.

(Comparative Example 2) -Ethylene vinyl acetate copolymer (41% by weight vinyl acetate) 15 parts [EVAFLEX 40Y, manufactured by Mitsui DuPont Polychemical Co., Ltd.]-Paraffin wax (melting point 75 ° C) 60 parts [HNP- 10, manufactured by Nippon Seiro Co., Ltd.]-Carnava wax (melting point 84 ° C) 10 parts-Carbon black 15 parts-Toluene 400 parts.

(Comparative Example 3) 35 parts of ethylene vinyl acetate copolymer (41% by weight of vinyl acetate) [EVAFLEX 40Y, manufactured by Mitsui DuPont Polychemical Co., Ltd.] 15 parts of paraffin wax (melting point: 75 ° C.) [HNP- 10, manufactured by Nippon Seiro Co., Ltd.] ・ Carnauba wax (melting point 84 ° C) 15 parts ・ Carbon black 35 parts ・ Silicon dioxide fine particles (average particle size 1.6 μm) 1 part [Mizukasil P-527, Mizusawa Chemical Industry Co., Ltd. Manufacturing] -Toluene 400 parts.

These ink films are cut into a predetermined width to prepare an ink ribbon, which is superposed on the heat-resistant lubricating layer 1
A load of kg / m ² was applied and the product was stored at 60 ° C. for 10 hours, and the heat-resistant storage stability was evaluated. Also, the print quality is Fujitsu
With a personal word processor (OASYS 30AX II) manufactured by
The resolution, rough surface paper coating, and sensitivity (high-speed followability) were evaluated according to the following criteria. The results are shown in Table 1.

Evaluation Criteria Sensitivity (high-speed followability) A: Ink is sufficiently transferred even if the print density scale is set to the center. ◯: Ink is sufficiently transferred even when the print density scale is set to the maximum. X: Incomplete transfer of ink is noticeable even on the highest print density scale, and patterns such as fine lines become discontinuous. Resolution ◎: Dot reproducibility is extremely good with patterns such as halftone dots and fine lines. ◯: Dot reproducibility is good with patterns such as halftone dots and thin lines. Δ: Fading or tailing occurs in a pattern such as halftone dots and thin lines. X: The print is faint and often trailed, making it difficult to read. Rough surface paper coating ◯: The void ratio (white spot ratio) in the solid black print area is less than 10%. X: The void ratio (white spot ratio) in the solid black print portion is 10% or more. Heat-resistant storage stability ◯: No fusion with heat-resistant lubricating layer occurs in a storage test at 60 ° C for 10 hours. X: Fusion with the heat-resistant lubricating layer occurs in a storage test at 60 ° C for 10 hours.

[0035]

[Table 1]

The evaluation results of the heat-meltable inks shown in Table 1 will be described below. In Comparative Example 1 in which no fine particles are added, there is no problem in print quality, but there is a problem in heat-resistant storage stability. On the other hand, in Examples 1 and 3, both requirements of print quality and heat-resistant storage stability can be satisfied. Comparative Example 2 in which heat-resistant storage stability can be maintained without adding fine particles
Since the blending amount of ethylene vinyl acetate copolymer, which is an adhesive component, was reduced to improve heat-resistant storage stability,
The transfer sensitivity was poor, and the resolution and rough surface paper coverage were also inferior to those of Example 1.

Further, in Comparative Example 3 in which fine particles having an average particle diameter smaller than the average coating thickness of the hot-melt ink were added, not only sufficient heat-resistant storage stability could not be obtained even if the addition amount was increased, but also fine particles were obtained. Causes the deterioration of the resolution and the covering of the rough surface paper. Furthermore,
In Example 2 in which the blending amount of the ethylene vinyl acetate copolymer, which is an adhesive component, was increased from that in Example 1, the resolution was further improved than in Example 1, and there was no problem with heat storage stability.

Examples 4 to 7 and Comparative Examples 4 to 6 PET having a heat-resistant lubricating layer formed on one side and a release layer containing paraffin wax as a main component on the other side with an average coating thickness of 1 μm
On the wax release layer side of the (polyethylene terephthalate) film, a heat-meltable ink prepared by the following composition was applied by a wire bar coater so that the average coating thickness of the heat-meltable ink layer was 2 μm, An ink film was created. The total coating thickness of the release layer and the heat-fusible ink layer of the obtained ink film is 3 μm.

(Example 4) -Ethylene vinyl acetate copolymer (41 wt% vinyl acetate) 35 parts [EVAFLEX 40Y, manufactured by Mitsui DuPont Polychemical Co., Ltd.]-Paraffin wax (melting point 66 ° C) 15 parts [HNP- 3. Made by Nippon Seiro Co., Ltd.] ・ Candelilla wax (melting point 70 ° C) 15 parts ・ Carbon black 35 parts ・ Low density polyethylene spherical fine particles (average particle size 5 μm) 0.5 part [FlowBeads LE-1080, Steel Chemical Industry Co., Ltd.]-Toluene 400 parts.

(Example 5) -Ethylene vinyl acetate copolymer (41% by weight vinyl acetate) 35 parts [EVAFLEX 40Y, manufactured by Mitsui DuPont Polychemical Co., Ltd.]-Paraffin wax (melting point 66 ° C) 15 parts [HNP- 3, manufactured by Nippon Seiro Co., Ltd.] ・ Candelilla wax (melting point 70 ° C.) 15 parts ・ Carbon black 35 parts ・ Silicon rubber spherical fine particles (average particle size 5 μm) 0.5 part [Trefill E-600, Toray Dow Corning Silicone ( Co., Ltd.]-Toluene 400 parts.

(Example 6) 35 parts of ethylene vinyl acetate copolymer (41% by weight of vinyl acetate) [EVAFLEX 40Y, manufactured by Mitsui DuPont Polychemical Co., Ltd.] 15 parts of paraffin wax (melting point 66 ° C.) [HNP- 3. Made by Nippon Seiro Co., Ltd.] ・ Candelilla wax (melting point 70 ° C.) 15 parts ・ Carbon black 35 parts ・ Silicon resin spherical fine particles (average particle size 4.5 μm) 0.5 parts [Tospearl 145, manufactured by Toshiba Silicone Co., Ltd. ] 400 parts of toluene.

(Example 7) -Ethylene vinyl acetate copolymer (vinyl acetate 28% by weight) 45 parts [EVAFLEX 220, manufactured by Mitsui DuPont Polychemical Co., Ltd.]-Paraffin wax (melting point 66 ° C) 15 parts [HNP- 3. Made by Nippon Seiro Co., Ltd.] ・ Candelilla wax (melting point 70 ° C) 5 parts ・ Carbon black 35 parts ・ Silicon resin spherical fine particles (average particle size 4.5 μm) 1 part [Tospearl 145, manufactured by Toshiba Silicone Co., Ltd. ] 400 parts of toluene.

(Comparative Example 4) 35 parts ethylene vinyl acetate copolymer (41% by weight vinyl acetate) [EVAFLEX 40Y, manufactured by Mitsui DuPont Polychemical Co., Ltd.] 15 parts paraffin wax (melting point 66 ° C.) [HNP- 3, manufactured by Nippon Seiro Co., Ltd.] ・ Candelilla wax (melting point 70 ° C.) 15 parts ・ Carbon black 35 parts ・ Toluene 400 parts.

(Comparative Example 5) -Ethylene vinyl acetate copolymer (41% by weight of vinyl acetate) 10 parts [EVAFLEX 40Y, manufactured by Mitsui DuPont Polychemical Co., Ltd.]-Paraffin wax (melting point 75 ° C) 60 parts [HNP- 10, manufactured by Nippon Seiro Co., Ltd.]-Carnauba wax (melting point 84 ° C) 15 parts-Carbon black 15 parts-Toluene 400 parts.

(Comparative Example 6) 35 parts ethylene vinyl acetate copolymer (41% by weight vinyl acetate) [EVAFLEX 40Y, manufactured by Mitsui DuPont Polychemical Co., Ltd.] 15 parts paraffin wax (melting point 66 ° C.) [HNP- 3, manufactured by Nippon Seiro Co., Ltd.] ・ Candelilla wax (melting point 70 ° C.) 15 parts ・ Carbon black 35 parts ・ Silicon resin spherical fine particles (average particle size 2 μm) 30 parts [Tospearl 120, manufactured by Toshiba Silicone Co., Ltd.] -Toluene 400 parts.

These ink films are cut into a predetermined width to prepare an ink ribbon, and the ink ribbon is superposed on the heat resistant lubricating layer.
A load of kg / m ² was applied and the product was stored at 60 ° C. for 10 hours, and the heat-resistant storage stability was evaluated. Also, the print quality is Fujitsu
With a personal word processor (OASYS 30AX II) manufactured by
The resolution, coating of rough surface paper, and sensitivity (high-speed followability) were evaluated in the same manner as in Examples 1 to 3 and Comparative Examples 1 to 4. The results are shown in Table 2.

[0047]

[Table 2]

The results of evaluation of the heat-meltable inks shown in Table 2 will be supplementarily described below. In Comparative Example 4 in which the spherical fine particles are not added, the print quality has no problem, but the heat-resistant storage stability has a problem. On the other hand, Examples 4 to 7 satisfy both requirements of print quality and heat-resistant storage stability. Furthermore, in Examples 4 to 7, even if a wax having a lower melting point than that in Examples 1 to 3 was used as a binder material, the heat-resistant storage stability could be maintained, so that the ink ribbons had higher sensitivity (high-speed followability). In Comparative Example 5 in which the heat-resistant storage stability can be maintained without the addition of spherical fine particles, the blending amount of the ethylene-vinyl acetate copolymer, which is an adhesive component, was reduced in order to improve the heat-resistant storage stability. However, the transfer sensitivity was poor, and the resolution and the rough surface paper coating were inferior to those of Examples 4 to 7.

Further, in Comparative Example 6 in which spherical fine particles having an average particle diameter smaller than the total average coating thickness of the total of the heat-meltable ink layer and the release layer were added, it is sufficient to increase the addition amount of the spherical fine particles. Not only the heat-resistant storage stability was not obtained, but also the addition of the spherical fine particles caused a decrease in resolution and a decrease in the coating on the rough surface paper. Further, the blending amount of the ethylene vinyl acetate copolymer, which is an adhesive component, was changed to that in Example 4.
In Example 7, the number of which was increased from 6 to 6, the resolution was further improved as compared with Examples 4 to 6, and there was no problem in heat-resistant storage stability.

[0050]

EFFECT OF THE INVENTION The thermal transfer recording medium of the present invention is excellent in heat-resistant storage stability, and printing with high sensitivity and excellent resolution can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a thermal transfer recording medium of the present invention.

FIG. 2 is a schematic sectional view showing another example of the thermal transfer recording medium of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fine particles 2 ... Thermofusible ink layer 3 ... Release layer 4 ... Base material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuji Maruyama 2606 Akabane, Kaigai-cho, Haga-gun, Tochigi Prefecture Kao Corporation Information Science Laboratory

Claims (7)

[Claims] 1. A thermal transfer recording medium comprising a base material and a coating layer containing at least one heat-fusible ink layer formed thereon, wherein the uppermost layer of the coating layer has a thickness larger than the average coating thickness. A thermal transfer recording medium comprising inorganic or organic fine particles having an average particle diameter. 2. The thermal transfer recording medium according to claim 1, wherein the fine particles are silicon dioxide. 3. The thermal transfer recording medium according to claim 2, wherein the content of silicon dioxide is 0.1 to 10% based on the weight of the uppermost layer. 4. A thermal transfer recording medium comprising a base material and a coating layer containing at least one heat-fusible ink layer formed on the base material, and the average coating of the entire coating layer in the uppermost layer of the coating layer. A thermal transfer recording medium comprising inorganic or organic fine particles having an average particle diameter larger than the thickness. 5. The thermal transfer recording medium according to claim 4, wherein the content of the inorganic or organic fine particles in the uppermost layer is 0.5 to 20% based on the weight of the uppermost layer. 6. The at least one release layer is provided below the heat-meltable ink layer closest to the substrate.
6. The thermal transfer recording medium according to any one of 5 above. 7. The fine particles have a spherical shape.
The thermal transfer recording medium according to any one of 1.