JP2694130B2 - Thermal transfer recording medium - Google Patents

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. More specifically, the present invention relates to a thermal transfer recording medium capable of finely printing on rough surface paper, having good abrasion resistance of a transferred image, and having improved running property. Recording medium

[0002]

2. Description of the Related Art The thermal transfer recording system uses a thermal transfer recording medium in which a heat-meltable ink layer containing a colorant and a binder is provided on a sheet-shaped substrate. A recording method in which recording media are superposed so that the heat-meltable ink layer contacts the transfer paper, and the ink layer is heated and melted by a heating head from the substrate side of the heat transfer recording medium to obtain a transfer image on the transfer paper. . According to this method, the apparatus to be used has been widely used in recent years because the apparatus to be used is low noise, has excellent operability and maintainability, and can use plain paper as a transfer paper.

When recording a transfer image on plain paper or the like using such a thermal transfer recording system, for example, a thermal transfer printer having a thermal head is generally used. However, as the performance of thermal transfer printers has increased, it has become desirable to reduce the thermal energy required for printing as low as possible. The reason for this is that by keeping the heat energy required for printing lower than before, the heating and cooling cycle time of the head can be shortened, and thermal deterioration of the head can be prevented, and especially for line printers, the power supply can be downsized. To become. Moreover, it is possible to compensate for the lack of heat resistance of the base material. However, if the melting point of the heat-meltable ink layer is designed to be low in order to keep the thermal energy required for printing low, background stains will occur due to the low-melting point component of the wax when printing on plain paper, and the print quality of the transfer layer will be poor. Not only is it deteriorated, but the abrasion resistance of the transferred image is not sufficient,
The problem of reduced robustness has arisen.

As a means for solving the above problems, it is proposed to control the melt viscosity of the binder within a specific range to improve the meltability of the heat-fusible ink layer or the peelability thereof. ing.

[0005] For example, Japanese Patent Laid-Open No. 126379/1989 discloses that a binder to be contained in a heat fusible ink layer is 1
By using an isocyanate polymer of lanolin fatty acid polyhydric alcohol ester having a melt viscosity of 60 to 50,000 cSt at 00 ° C., the dispersibility of the colorant is good, and the heat-meltable ink layer melts with a small heating energy. Medium is suggested. However, in the above publication, the melt viscosity at 100 ° C. is 70 to
Only the isocyanate polymer of 1800 cSt lanolin fatty acid polyhydric alcohol ester is specifically described, and the melt viscosity at 100 ° C. is 2000 to 70.
There is no mention of using a 00 cSt version.

Further, Japanese Patent Laid-Open No. 3-63182 discloses that
As a binder to be contained in the heat-meltable ink layer, 100
By using an isocyanate polymer of a higher fatty acid pentaerythritol ester having a melt viscosity at 10 ° C. of 10 to 1000 cSt, a thermal transfer recording medium which has good ink cutting property and transferability and can form a transfer image having a uniform density is obtained. Has been suggested. However, the above publication only specifically describes an isocyanate polymer of lanolin fatty acid pentaerythritol ester having a melt viscosity at 100 ° C. of 31 to 83 cSt.

These thermal transfer recording media in the prior art improve transferability to rough surface paper, abrasion resistance of a transferred image, and print quality to some extent, but they have never been satisfactory. On the other hand, as a means for solving the above problems, it has been proposed to reduce the thickness of the base material to enhance heat transfer to achieve low energy printing. However, there are problems that the blackness of the transferred image is lowered and the running property of the ink ribbon becomes unstable. Therefore, an object of the present invention is to provide a thermal transfer recording medium excellent in these characteristics.

[0008]

As a result of intensive studies, the present inventors have found that a substance having a specific melt viscosity as a binder and a substance having a specific oil absorption amount as a colorant in a hot-melt ink layer. It was found that the above object can be achieved by using together.

The present invention has been made on the basis of the above findings, and in a thermal transfer recording medium comprising a base material and a heat-meltable ink layer, the heat-meltable ink layer comprises 10
The above object is achieved by providing a thermal transfer recording medium characterized by containing a binder having a melt viscosity at 0 ° C. of 2000 to 7000 cSt and a colorant having an oil absorption of 60 ml / 100 g or less.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The thermal transfer recording medium of the present invention will be described in detail below.

The hot melt ink layer contains a colorant and a binder. And, as the above-mentioned binder, in the present invention, the melt viscosity at 100 ° C. is 2000 to 700.
At least 0 cSt binder is used. In the conventional thermal transfer recording medium, for example, the above-mentioned JP-A-1-126 is used.
Although the '379 publication suggests the use of binders with a wide range of melt viscosities of 60 to 50,000 cSt,
Specifically, the melt viscosity at 100 ° C is 1800 cSt.
Only the use of the following binders is mentioned. On the other hand, surprisingly, the present inventors can significantly improve the print quality and the like as compared with the conventional thermal transfer recording medium by using the binder having the melt viscosity of 2000 to 7000 cSt at 100 ° C. It has been found that a thermal transfer recording medium can be obtained. That is, the melt viscosity is 20
If it is less than 00 cSt, the cohesive force is weak and it is difficult to form a uniform transferred image. If the melt viscosity is more than 7000 cSt, the ink runs out and the transferred image has poor resolution. The preferable range of the melt viscosity is 2000 to 300.
0 cSt.

Any binder may be used without particular limitation as long as it has a melt viscosity at 100 ° C. in the range of 2000 to 7000 cSt. Examples of such a binder include polyester resin, polyether resin, polyamide resin, polystyrene resin, ethylene-
Examples thereof include vinyl acetate copolymers and vinyl chloride-vinyl acetate copolymers.

The preferred binder is an isocyanate polymer of higher fatty acid polyhydric alcohol ester (hereinafter simply referred to as "isocyanate polymer"). The above-mentioned isocyanate polymer is obtained by addition-reacting an isocyanate compound with an esterified product of a higher fatty acid and a polyhydric alcohol. The above-mentioned isocyanate polymer is contained in the above heat-meltable ink layer by one kind or two or more kinds.

The preparation of the above isocyanate polymer will be described below. Saturated fatty acids, unsaturated fatty acids, alicyclic fatty acids, oxygen-containing fatty acids, hydroxy fatty acids and the like can be used as the higher fatty acid for obtaining the esterified product. The number of carbon atoms in these fatty acids is not particularly limited, but is generally 2 to 60, preferably 5 to 50, and particularly preferably 10 to 40. In the present invention, a fatty acid having a melting point of 20 ° C. or higher and a carbon number of 10 to 40 can be preferably used, and examples thereof include capric acid, undecyl acid, lauric acid, tridecyl acid, myristic acid, pentadecyl acid, palmitic acid, and heptadecyl acid. Saturated fatty acids such as, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, heptacosanoic acid, montanic acid, melissic acid, and raceric acid; acrylic acid, crotonic acid, isocrotonic acid, caproic acid, undecylenic acid, Unsaturated fatty acids such as oleic acid, elaidic acid, cetoleic acid, erucic acid, brassic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid, sardonic acid, nisinic acid, propiolic acid, stearolic acid; isovaleric acid and the like. Branched fatty acids, malvalic acid, stercri Acid, Hidonokarubin acid, Shorumu - Glynn acid,
Alicyclic fatty acids such as golulinic acid; sabinic acid, iprolic acid, yarapinolic acid, uniperic acid, ricinoleic acid,
Oxygen-containing fatty acids such as cerebronic acid; hydroxy fatty acids such as 12-hydroxystearic acid can be used. These fatty acids may be used alone or in combination of two or more.

On the other hand, as the polyhydric alcohol for obtaining the esterified product, a saturated aliphatic polyol, an unsaturated aliphatic polyol, an alicyclic polyol, an oxygen-containing aliphatic polyol or the like can be used. The number of carbon atoms in these polyols is not particularly limited, but is generally 1 to 50, preferably 1 to 20, and particularly preferably 1 to
It is 10. In the present invention, for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol,
Polypropylene glycol, trimethylene glycol,
Butanediol, pentanediol, hexylenediol, octylenediol, glycerin, trimethylolpropane, pentaerythritol, dipentaerythritol, 1,3-butylene glycol, glycerin monoallyl, [4- (hydroxyethoxy) phenol] propane, sorbitol , Sorbit, neopentyl glycol, trishydroxyethyl isocyanurate, bisphenol, hydrogenated bisphenol, bisphenol glycol ether, various epoxy group-containing compounds (for example,
Triglycidyl isocyanurate) or the like is used. These polyhydric alcohols may be used alone or in combination of two or more.

As the above-mentioned isocyanate compound to be added to the above-mentioned esterified product, monoisocyanate, diisocyanate, triisocyanate and the like can be used. For example, methyl isocyanate, ethyl isocyanate, n-propyl isocyanate, n-butyl isocyanate, octadecyl isocyanate. Monoisocyanates such as polymethylene polyphenyl isocyanate;
2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, dianisidine diisocyanate, metaxylylene diisocyanate, 1,5-naphthalene diisocyanate, trans vinylene diisocyanate, N, N '(4,4'-dimethyl-3, 3'-
Diphenyldiisocyanate) diisocyanates such as urezion and 2,6-diisocyanate methylcaproate; triphenylmethane triisocyanate, tris (4-phenylisocyanate thiophosphate) 4,
Each isocyanate of 4 ', 4 "-trimethyl-3,3', 3" -triisocyanate-2,4,6-triphenylcyanurate and other triisocyanates can be used. Particularly, diisocyanate and triisocyanate are preferable, and aromatic type is more preferable. These isocyanate compounds may be used either individually or in combination of two or more.

The esterification reaction of the higher fatty acid and the polyhydric alcohol can be carried out by any conventionally known method. The degree of esterification is not particularly limited. The addition reaction of the esterified product prepared according to the above method and the above isocyanate compound can be carried out according to a conventionally known method. The number of moles of the isocyanate compound added is not particularly limited, but is preferably about 0.1 to 5 moles per 1 mole of the esterified product.

Particularly preferred as the above-mentioned isocyanate polymer is an isocyanate polymer of lanolin fatty acid polyhydric alcohol ester using lanolin fatty acid obtained by saponifying lanolin secreted from the sebaceous glands of sheep as the higher fatty acid. Is.

As the isocyanate polymer of the above lanolin fatty acid polyhydric alcohol ester, a commercially available product may be used. For example, Ranox FPK- manufactured by Yoshikawa Oil Co., Ltd.
120 (melt viscosity at 100 ° C .: 2730 cS
t), FPK-310 (melt viscosity at 100 ° C .: 3
600 cSt) and FPK-220 (melt viscosity at 100 ° C .: 4500 cSt), FPK-410 (100).
Melt viscosity at ℃: 6000 cSt) or the like can be used. Above all, it is desirable to use FPK-120.

The binder is contained in the heat-fusible ink layer in an amount of 20 to 500 relative to 100 parts by weight of the colorant described later.
It is preferably contained in an amount of 40 parts by weight, more preferably 40 to 400 parts by weight.

In the thermal transfer recording medium of the present invention, the heat-meltable ink layer may contain a binder other than the isocyanate polymer. Suitable as such a binder is an ethylene-vinyl acetate copolymer. It is preferable to use such an ethylene-vinyl acetate copolymer together with the above-mentioned isocyanate polymer (particularly, the isocyanate polymer of lanolin fatty acid polyhydric alcohol ester) because the resolution of the transferred image during high-speed printing is further improved.

The ethylene-vinyl acetate copolymer preferably has a melt flow rate (hereinafter referred to as "MFR") of 5 to 2000 dg / min, preferably 5 to 2000 dg / min.
Those of 1000 dg / min are particularly preferable. Above MF
If R is less than 5 dg / min, the ink may run out,
The resolution of the transferred image may deteriorate, and the MFR is 2
If it exceeds 000 dg / min, ink flow or the like may occur and normal and uniform thermal transfer recording may not be possible.

The ethylene-vinyl acetate resin is preferably contained in the heat-meltable ink layer in an amount of 20 to 400 parts by weight, preferably 30 to 300 parts by weight, based on 100 parts by weight of the coloring agent described later. Is more preferable. If the content is less than 20 parts by weight, problems such as scumming may occur, and if the content exceeds 400 parts by weight, the transferred image lacks abrasion resistance, and the sensitivity decreases, resulting in high speed printing. In that case, the resolution may be lowered, so that it is preferably within the above range.

If desired, other binder may be added to the heat-meltable ink layer. As the binder to be added, for example, styrene, vinyltoluene, α-
Examples thereof include homopolymers and copolymers of styrene such as methylstyrene, chlorostyrene, vinyl benzoic acid, sodium vinylbenzene sulfonate, and aminostyrene, and their derivatives and substitution products. Further, methacrylic acid esters and methacrylic acid such as methyl methacrylate, ethyl methacrylate, butyl methacrylate and hydroxymethacrylate; acrylic acid esters and acrylic acid such as methyl acrylate and 2-ethylhexyl acrylate; dienes such as butadiene and isoprene; acrylonitrile, vinyl ethers. , And maleic acid and maleic acid esters, maleic anhydride, cinnamic acid, and vinyl monomers such as vinyl chloride; homopolymers or copolymers with other monomers can also be used. Of course, in the case of the vinyl-based polymer, a polyfunctional monomer such as divinylbenzene may be used as a cross-linked polymer. Furthermore, polycarbonate, polyester, silicone resin, fluorine resin, phenol resin, tempene 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 copolymers, the copolymers include random copolymers, alternating copolymers, block copolymers and interpenetrating copolymers, depending on the required application. A copolymerization mode such as the above can be appropriately selected and used. Also,
When two or more kinds of polymers or oligomers are mixed and used, in addition to mechanical mixing such as melt mixing, solution mixing and emulsion mixing, they are mixed by co-polymerization or multi-stage polymerization method at the time of polymerizing the polymer or oligomer components. Good. The other binder is contained in the heat-fusible ink layer as the colorant 10 described later.
It is preferable to add up to 100 parts by weight with respect to 0 parts by weight.

Next, the colorant will be described.
As the colorant, at least one having an oil absorption of 60 ml / 100 g or less is used. The colorant may be used without particular limitation as long as its oil absorption is within a range of 60 ml / 100 g or less. The oil absorption is 6
If the amount exceeds 0 ml / 100 g, the viscosity of the ink paint increases, the resolution of the transferred image decreases, and the running property deteriorates.
The oil absorption amount is a value measured by the DBP (dibutyl phthalate) method (ASTM D2414-65T). The oil absorption is preferably 5 to 60 ml / 100 g, more preferably 10 to 60 ml / 100 g.

Examples of such colorants include black dyes and pigments such as carbon black, oil black and graphite;
C. I. Pigment Yellow 1, the same 3, the same 74, the same 9
Acetoacetic acid arylamide-based monoazo yellow pigments (Fast Yellow), such as 7 and 98; C.I. I. Pigment Yellow 12, 13 and 14 and the like, acetoacetic acid arylamide-based bisazo yellow; C.I. I. Solvent Yellow 1
9, ibid. 77, ibid. 79, C.I. I. Yellow dyes such as Disperse Yellow 164; I. Pigment Red 8, 49: 1, 53: 1, 57: 1, 81:12
Red pigments such as 2 and 5; C.I. I. Solvent Red 5
2, 58, 8 and the like red dyes; C.I. I. Pigment Blue 15: 3 and the like, copper phthalocyanine and its derivatives, and modified dyes and the like can be used. In addition, colored and colorless sublimable dyes, conventional printing inks, and dyes and pigments well known in other coloring applications can be used. These dyes and pigments may be used alone or in combination of two or more. Of course, the color tone may be adjusted by mixing with an extender or a white pigment. Furthermore, in order to improve the dispersibility in the binder, the surface of the colorant is treated with a surfactant, a coupling agent such as a silane coupling agent, or a polymer material, or as a colorant, a polymer dye or a high-molecular dye is used. A molecular graft pigment may be used. Of these colorants, it is particularly preferable to use a black pigment.

Further, the above-mentioned coloring agent has an apparent density of 2
It is preferably from 00 to 400 g / cm ³ . If the apparent density is less than 200 g / cm ³ , the dispersibility of the ink coating composition may deteriorate, the blackness may decrease, and voids may increase during solid black coating.
If it exceeds ³ cm3, the viscosity of the ink coating may increase, the resolution of the transferred image may decrease, and the running performance may deteriorate.
It is preferable to be within the above range. The apparent density can be measured, for example, from the weight when the colorant is filled in a container having a constant volume. The apparent density is more preferably from 200~350g / cm ^3, and still more preferably 250-350 g / cm ^3.

In addition, organic or inorganic fine particles may be added to the heat-meltable ink layer for the purpose of improving heat resistance stability.

Further, if necessary, waxes, oils, (liquid) plasticizers, or resins such as those used for the heat-melting substance in the conventional heat transfer recording medium are added to the heat-melting ink layer. May be. In addition to these, ethylene, olefin homopolymers or copolymers such as propylene, organic acid-grafted olefin copolymers, chlorinated paraffins, low-molecular urethane compounds, plasticizers solid at room temperature,
Charge control and / or prevention agents such as surfactants, conductive agents, antioxidants, thermal conductivity improvers, magnetic materials, strong derivatives,
An antiseptic, a fragrance, an antiblocking agent, a reinforcing filler, a release agent, a foaming agent, a sublimable substance, an infrared absorbing agent and the like may be added to the above heat-meltable ink layer or other layers.

The thickness of the heat-meltable ink layer is not particularly limited, but is preferably about 0.1 to 10 μm.

The heat-meltable ink layer is provided on the base material. As such a base material, it is preferable to use a base material having heat resistance and high dimensional stability and surface smoothness.
More specifically, in addition to papers such as capacitor paper, glassine paper and synthetic paper, which are conventionally mainly used as a base film of a thermal transfer recording medium, and polyethylene terephthalate, polycarbonate, polyethylene, polystyrene,
Thin film sheets or films of resin films such as polypropylene, polyimide and polyamide can be used without particular limitation. The thickness of the base material is not particularly limited, but a range of about 1.5 to 20 μm is suitable.

Further, in the thermal transfer recording medium of the present invention, in order to further improve heat resistance and running property on the surface of the base material opposite to the surface on which the heat-meltable ink layer is provided. The back coat layer may be provided. Such a back coat layer is particularly advantageous when a thermal head is used as a heat source for thermal transfer.

The back coat layer is generally composed of a nitrocellulose-based, silicone-based or fluorine-based compound.
Preferably, the back coat layer is a reaction product of an amino-modified silicone oil (for example, a silicone oil in which an amino group is introduced into a part of a methyl group of dimethylpolysiloxane) and a polyfunctional isocyanate (for example, TDI) or a silicone. Consisting of butyral resin. Generally, the thickness of the back coat layer is preferably 0.01 to 0.5 μm, but is not limited to this range.

In the thermal transfer recording medium of the present invention, a release layer may be provided between the substrate and the heat-meltable ink layer. By providing the release layer, a highly sensitive thermal transfer recording medium can be obtained. The peeling wax used in the peeling layer is preferably one or more selected from the group consisting of natural wax, synthetic wax and compounded wax. Further, in addition to the above peeling waxes, in order to improve coating strength and flexibility, resins such as ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, polyethylene and petroleum resin may be added. Good.

Further, the thermal transfer recording medium of the present invention may be provided with an overcoat layer, a resistance layer for energizing and heating.

Next, the method for producing the thermal transfer recording medium of the present invention will be described based on its preferred embodiment. To produce the thermal transfer recording medium of the present invention, on the base material (or on the release layer when the release layer is provided on the base material).
A heat-meltable ink coating is applied to the above to form a heat-meltable ink layer.

The above hot-melt ink coating composition is a ball mill, a ball mill, a solution or dispersion emulsion of the above colorant, the above binder and other optional components in a solvent or dispersion medium in which the above binder can be dissolved or stably dispersed. It is obtained by mixing using a mixing and dispersing machine such as a sand mill, an attritor, a dyno mill, or a three-roll mill. In addition, after the above colorant is dispersed by the above method, fine particles may be added and stirred and mixed by a homomixer, a disper, a dissolver or the like. Furthermore,
You may melt-mix with a three roll, a kneader, a sand mill, an attritor etc., without using a solvent etc.

The hot-melt ink coating composition prepared as described above is applied to the base material (or the release layer when the release layer is provided on the base material), a gravure coater, a wire bar, or the like. Is applied by a solution or melt coating method. Further, the hot-melt ink coating material is pulverized by a spray dry method, and then electrostatically coating method or the like on the base material (or the release layer when the release layer is provided on the base material). It may be powder coated. In this case, after the powder coating, if necessary, heating, pressurization, solvent treatment, etc. are performed to apply the heat-meltable ink coating material to the base material (when the release layer is provided on the base material). Alternatively, it may be fixed on the release layer).

[0039]

EXAMPLES The thermal transfer recording medium of the present invention will be described below in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition, "parts" represents parts by weight unless otherwise specified.

Example 1 A heat-meltable ink prepared from the following components was formed on the above wax release layer of a polyethylene terephthalate film having a heat-resistant lubricating layer formed on one surface and a wax release layer formed on the other surface. Is coated with a wire bar coater so that the film thickness after drying is 2 μm,
It was dried to form a heat-meltable ink layer. This film was cut into a predetermined width to produce an ink ribbon.

Isocyanate adduct of higher fatty acid polyhydric alcohol ester [Lanox FPK-120 (manufactured by Yoshikawa Oil Co., Ltd.), melt viscosity at 100 ° C .: 2730
cSt]; 40 parts-Ethylene-vinyl acetate copolymer [EVAFLEX-4
0Y (manufactured by Mitsui DuPont Polychemical Co., Ltd.), MFR:
60 dg / min]; 25 parts-Carbon black (REGAL415R, made by Cabot, oil absorption: 55 ml / 100 g, tinting strength index: 12
5, specific surface area 90 m ² / g); 35 parts-toluene; 400 parts

In order to evaluate the performance of the ink ribbon thus obtained, the printing quality, abrasion resistance and running property of the transferred image were measured using this ink ribbon by the following methods. Table 1 shows the results.

<Measurement of print quality> A black solid transfer image was formed on a rough surface paper (Beck smoothness: 42.5 seconds), and the void ratio (blank area ratio) of the black solid print portion was measured.

<Measurement of Friction Resistance> After printing a halftone dot pattern with a printing rate of 7.5% on smooth paper (Beck smoothness 410.6 seconds), the eraser was reciprocated 3 times under a load of 500 g and the friction portion The transfer area with the non-rubbed portion was measured with an image analyzer. The value of the friction resistance is represented by [transfer area of friction part / transfer area of non-rubbing part] × 100 (%).

<Measurement of runnability> Smooth paper (Beck smoothness 4
The ribbon releasability of the 1-dot thin line for 10.6 seconds) was visually determined.

[Examples 2 and 3 and Comparative Examples 1 and 2]
Instead of Lanox FPK-120 in Example 1,
An ink ribbon was obtained in the same manner as in Example 1, except that the isocyanate adduct of higher fatty acid polyhydric alcohol ester shown in Table 1 was used. The same measurement as in Example 1 was performed on this ink ribbon. Table 1 shows the results.

Example 4 An ink ribbon was obtained in the same manner as in Example 2, except that the black pigment shown in Table 1 was used instead of the carbon black REGAL415R in Example 2. The same measurement as in Example 1 was performed on this ink ribbon. Table 1 shows the results.

Comparative Examples 3 and 4 An ink ribbon was obtained in the same manner as in Example 1, except that the black pigment shown in Table 1 was used instead of the carbon black REGAL415R in Example 1. About this ink ribbon Example 1
The same measurement was performed. Table 1 shows the results.

[0049]

[Table 1]

As is clear from the results in Table 1, an ink provided with a heat-meltable ink layer containing a binder having a melt viscosity of 2000 to 7000 cSt at 100 ° C. and a colorant having an oil absorption of 60 ml / 100 g or less. The transfer images obtained by using the ribbons (Examples 1 to 4) are capable of forming a transfer image with high printing quality even on rough surface paper, and the transfer images have high abrasion resistance. It was Especially 10
The transfer image obtained by using the ink ribbon (Example 1) provided with the heat-meltable ink layer containing the binder having a melt viscosity at 0 ° C. of 2000 to 3000 cSt was the print quality of the transfer image and abrasion resistance. The wear resistance and the running property were extremely high.

On the other hand, in the ink ribbon (Comparative Example 1) provided with the hot-melt ink layer containing the binder having the melt viscosity at 100 ° C. of 12000 cSt (Comparative Example 1), with respect to the abrasion resistance, there was a chip after abrasion. Somewhat recognized. Regarding the runnability, peeling was not performed normally and printing stopped halfway.

The melt viscosity at 100 ° C. is 160
In the ink ribbon provided with the heat-meltable ink layer containing the binder of 0 cSt (Comparative Example 2), the transferred image on the rough surface paper was notable for practical use because white spots were conspicuous.

Further, in the ink ribbon (Comparative Example 3) provided with the heat-meltable ink layer containing the colorant having the oil absorption of 188 ml / 100 g, the transfer was not performed.

Furthermore, in the ink ribbon (Comparative Example 4) provided with a heat-meltable ink layer containing a colorant having an oil absorption of 114 ml / 100 g, white spots were conspicuous on the transfer image of the rough surface paper, and it was practically used. It was unbearable. Further, the peeling was not performed normally, and the printing was stopped halfway. Moreover, a chip after rubbing was slightly recognized.

[0055]

As described above in detail, according to the thermal transfer recording medium of the present invention, the melt viscosity of the binder and the oil absorption of the colorant contained in the heat-fusible ink layer are controlled within a specific range. It is possible to remarkably improve all basic ribbon performances such as transferability to rough surface paper, abrasion resistance of transferred image and running property.

Claims (5)

(57) [Claims] 1. A thermal transfer recording medium comprising a substrate and a heat-meltable ink layer provided thereon, wherein the heat-meltable ink layer has a binder having a melt viscosity at 100 ° C. of 2000 to 7000 cSt and 60 ml / 10.
A thermal transfer recording medium comprising a colorant having an oil absorption of 0 g or less. 2. The thermal transfer recording medium according to claim 1, wherein the binder has a melt viscosity at 100 ° C. of 2000 to 3000 cSt. 3. The thermal transfer recording medium according to claim 1, wherein the binder is an isocyanate polymer of a higher fatty acid polyhydric alcohol ester. 4. The isocyanate polymer of higher fatty acid polyhydric alcohol ester is an isocyanate polymer of lanolin fatty acid polyhydric alcohol ester.
The thermal transfer recording medium described. 5. The colorant is a black pigment.
The thermal transfer recording medium described.