JP3406568B2 - Ink ribbon for hot melt transfer - 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 melt transfer ink ribbon suitable for multi-time printing. More specifically, the present invention provides the use of specific inks,
The present invention relates to an ink ribbon for thermal fusion transfer, which reduces a decrease in print density during multi-time printing.

[0002]

2. Description of the Related Art Thermal transfer recording is a recording method in which a thermal transfer recording medium, that is, an ink ribbon is selectively heated according to image information to transfer the ink from the ink ribbon to a transfer target such as recording paper. Thermal melting transfer recording, in which ink is melt-transferred from an ink ribbon to a transfer target, is sometimes widely used.

By the way, as an ink ribbon, conventionally,
Once used for thermal transfer recording, the ink layer in that portion is entirely transferred to the transfer target, so it was for one-time use that cannot be used repeatedly. However, in recent years, there has been a demand for a multi-time ink ribbon which can be used repeatedly many times, and its development has been attempted. For example, as a multi-time ink ribbon, its ink layer is formed by sequentially stacking ink and a resin in which a filler is dispersed in layers, and at the time of transfer, the ink layers formed in layers are transferred one by one. What has been done is proposed. Further, as a more preferable form, it is formed by holding ink in a porous resin layer so that the ink in a molten state partially moves from the porous resin layer to the transfer target at the time of transfer, and even after the transfer. There has also been proposed one in which ink remains in the ink layer. As such a porous resin layer, beads, a resin in which a filler such as carbon is dispersed, and a resin having properties different from this are mixed, and the mixture is applied to a base material and cured, It is known that only the above resin is dissolved and removed by a solvent. It is also known that a resin is dissolved in a volatile solvent such as toluene, xylene, or methyl ethyl ketone, and the solution is applied to a substrate and then dried to remove the volatile solvent to make it porous. .

[0004]

However, even if the conventional multi-time ink ribbon in which the ink is held in the porous resin is used, there is a problem that it is not possible to satisfactorily perform repeated printing many times. It was That is, conventionally
It is difficult to form a uniform and high porosity for a porous resin layer for use in multi-time ink ribbons, and therefore it is not possible to hold a sufficient amount of ink in the pores, and printing quality Was occurring. Furthermore, since a large amount of ink is used at the time of the first transfer, there is a problem that the printing density is greatly reduced as the printing is repeated many times, and good printing quality cannot be maintained.

The present invention is intended to solve the problems of the prior art as described above, and an ink ribbon for hot-melt transfer capable of maintaining good printing quality even when used for repeated transfer many times. Is intended to provide.

[0006]

The present inventor has formed an ink layer of an ink ribbon used for thermal fusion transfer recording by holding the ink on a specific porous film, and further increases the viscosity of the ink. It has been found that it is effective to complete the present invention.

That is, according to the present invention, an ink ribbon for thermal fusion transfer having a support and an ink layer, the ink layer comprising an ink held on a porous film, has an ink viscosity of 1000 to 5000 cps at 120 ° C. The present invention also provides an ink ribbon for thermal melt transfer, wherein the porous film is formed by biaxially stretching polytetrafluoroethylene.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of an ink ribbon 10 according to one embodiment of the present invention, in which a support 1, a conductive layer 2 and an ink layer 3 are sequentially laminated.

Here, the support 1 is preferably a support made of a heat-resistant resin such as aramid or polyimide so that it does not shrink due to transfer and can withstand a large number of transfers. Further, when a printer of an electrically heat-sensitive type is used as the printer, it is preferable to use, as the heat resistant support, a conductive support made of a heat resistant resin such as conductive aramid in which carbon is contained in aramid.

As the conductive layer 2, for example, a metal film of gold, copper, aluminum or the like can be used. This conductive layer 2
May be formed as a vapor deposition film. Alternatively, they may be laminated via an adhesive. The conductive layer 2 is not necessarily required in the ink ribbon of the present invention, but is provided when the printer of the electrically heat-sensitive type is used. In this case, the current density in the conductive layer 2 becomes excessively high,
The conductive layer 2 is formed to have an appropriate thickness (about 500 to 1000 angstrom) so that the current does not easily flow. This makes it possible to improve the efficiency of heat generation in the case of transfer by the energization heat sensitive method.

On the other hand, in the case of using a printer having a normal thermal head which is not the heat-sensitive type, the conductive layer 2 is not formed as described above, and the ink ribbon is used as the support 1 and the ink described below. Although it can be formed in a two-layer structure with the layer 3, the conductive layer 2 is preferably provided in this case as well so that the heat of the thermal head can be efficiently transmitted to the ink layer.

In the present invention, as the ink layer 3, a porous film holding ink is used.
As the porous film, a resin such as polytetrafluoroethylene (PTFE), polypropylene, polyester, or high-density polyethylene is used, and the porosity is 90% by the stretching method.
It is preferable to use a resin film formed so that In particular, biaxially stretched polytetrafluoroethylene (PTFE) is preferable from the viewpoint of obtaining a film having a high porosity. By using a film having a high porosity as described above, it is possible to increase the amount of ink held in the pores, and it is possible to improve the transferability by repeating many times. Further, when the porosity is low, the film matrix is dense, and the pigment of the ink such as carbon black is blocked by the film matrix and is difficult to transfer to the transfer target, which lowers the transfer density. But
By increasing the porosity, it is possible to prevent such a decrease in transfer density.

As a method for holding the ink in the porous film, the ink may be impregnated into the pores of the film by a conventional method.

Further, in the present invention, the ink retained on the porous film as described above has a viscosity of 120.
A highly viscous material having a viscosity of 1000 to 5000 cps at a temperature of 1000 ° C. As such a high-viscosity ink, it is preferable to use an ink exhibiting a characteristic of 3000 to 10000 cps at 80 ° C. If the viscosity of the ink is lower than this range, a large amount of ink is melt-transferred at each transfer, and sufficient print density is obtained at the 1st to 3rd transfers, but the print density is lowered at the 4th and subsequent transfers. However, good printing quality cannot be obtained. On the other hand, when the viscosity of the ink is higher than the above range, the amount of melt transfer at the time of transfer is reduced, and a sufficient print density cannot be obtained. To adjust the viscosity of the ink to such a value, the compounding ratio of the components of the ink may be appropriately changed, and as the compounding component of the ink itself, the same colorant, binder, softening agent and the like as in the conventional ink can be used.

For example, as the colorant, various pigments such as carbon black can be used.

Examples of the binder include waxes such as carnauba wax, paraffin wax, candelilla wax, wood wax, beeswax, ester wax and polyethylene wax, higher fatty acids such as stearic acid, palmitic acid and lauric acid, Higher alcohols or metal salts or ester derivatives thereof can be used.

As the softening agent, for example, resins such as petroleum resin, polyamide resin, polystyrene resin, styrene-butadiene copolymer, acrylic resin, ethylene-vinyl acetate copolymer, and oils such as mineral oil and vegetable oil are used. can do.

According to the ink ribbon of the present invention, since the ink layer is formed of the porous film holding the ink, it is possible to hold a sufficient amount of the ink in the ink layer. Furthermore, as the ink in this case,
Its viscosity is 1000-5000 cps at 120 ° C
Since a high-viscosity material is used, the amount of ink melt-transferred onto the transfer-receiving material can be suppressed to an appropriate amount for each transfer, resulting in good printing quality with high printing density even when printing is repeated many times. It can be sustained.

[0020]

EXAMPLES The present invention will be specifically described below based on examples.

Example 1 An ink ribbon having the layer structure shown in FIG. 1 was prepared. In this case, a conductive aramid film (3.6 kΩ / □) (manufactured by Toray Industries, Inc.) having a thickness of 10 μm is used as the support 1, and an aluminum vapor-deposited film having a thickness of 1000 Å is used as the conductive layer 2. Formed. As the ink layer 3, a porous film having a porosity of 99.5% and a thickness of 10 μm obtained by biaxially stretching polytetrafluoroethylene was impregnated with ink. In this case, as the ink, one having the following ink composition and ink characteristics was used.

[0022]   (Ink composition)     Carbon black 20% by weight     Paraffin wax (manufactured by Nippon Seirou Co., Ltd., HNP-3WAX) 48% by weight     Carnauba wax (Toyo Petrolite) 20.5% by weight     Softener: EVA 7.5% by weight     Dispersant: MEK 4% by weight   (Ink characteristics)     Melting point 65 ° C     Viscosity 3000cps / 80 ℃                     1000cps / 120 ° C

An adhesive having the following composition having a thickness of 1 to 3 μm was used as an adhesive between the conductive layer 2 and the ink layer 3 and gripped.

[0024]   (Adhesive composition)     Acrylic pressure sensitive adhesive 39.7% by weight     (Sanyo Kasei Co., Ltd., Polychic 410-SA)     Polyisocyanate 0.8% by weight     (Sanyo Kasei Co., Ltd., Polythic 410-SC)     Ethyl acetate 59.5% by weight

Examples 2 to 5 and Comparative Examples 1 to 3 Ink ribbons were prepared in the same manner as in Example 1 except that the inks having the composition ratios and characteristics shown in Table 1 were used.

[0026]

[Table 1] Examples Comparative Examples 1 2 3 4 5 1 2 3 (ink composition: wt%) Carbon black 20 20 26.3 26.3 26.3 20 20 26.3 Paraffin wax 48 46.2 44.6 47.1 46.7 53.2 51.5 42.4 Carnauba wax 20.5 19.8 18.8 13.9 11.75 22.8 22 11.05 EVA 7.5 10 5 7.5 10 0 2.5 15 MEK 4 4 5.3 5.2 5.25 4 4 5.25 (Ink characteristics) Melting point (℃) 65 65 65 65 65 65 65 65 Viscosity 80 ℃ (cps) 3000 3910 3660 4680 8300 170 651 37000 120 ℃ ( cps) 1000 2300 2560 2870 4410 100 391 14600

(Evaluation) Using the ink ribbons obtained in Examples 1 to 5 and Comparative Examples 1 to 3, multi-time printing was performed on recording paper using a printer of an electric heat-sensitive transfer system under the following printing conditions. Solid black reflection density O. D. Was measured using a densitometer (RD-918, manufactured by Mcbeth). The results are shown in Fig. 2. In this case, the reflection density O.D. D. FIG. 3 shows the relationship between the number of times printing is possible and the ink viscosity is 1 or more.

[0028]   (Printing conditions)     Serial head (recording electrode) tungsten (φ0.06),                   0.125 pitch, 32     Return electrode Stainless steel (φ2)     Distance between electrodes 37mm     Printing speed 19.6cps (character size 4x4)     Printing voltage 0.22-0.5mJ / dot     Print pattern solid black, font

As is apparent from FIGS. 2 and 3, 120
The ink ribbons of the examples of the present invention using the ink having the viscosity of 1000 to 5000 cps at the temperature of 0 ° C. were excellent in multi-time printability.

[0030]

According to the ink ribbon of the present invention, it is possible to maintain good print quality even when it is used for repeated transfer many times.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an ink ribbon of the present invention.

FIG. 2 shows the number of times of printing and the reflection density of the printed matter when the ink ribbons of Examples and Comparative Examples were used. D. FIG.

FIG. 3 is a reflection density O.D. of printed matter when the ink ribbons of Examples and Comparative Examples are used. D. FIG. 6 is a relational diagram between the ink viscosity and the number of times of printing when is 1 or more.

[Explanation of symbols]

1 Support, 2 Conductive Layer, 3, Ink Layer, 10 Ink Ribbon

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-55-105579 (JP, A) JP-A-4-16386 (JP, A) JP-A-2-273278 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B41M 5/38-5/40

Claims (4)

(57) [Claims] 1. A thermal melt transfer ink ribbon comprising a support and an ink layer, the ink layer comprising an ink held on a porous film, wherein the viscosity of the ink is 120.degree.
In 1000 to 5000 cps, and the porous film is formed by biaxially stretching polytetrafluoroethylene. 2. The ink has a viscosity of 3000 at 80 ° C.
The ink ribbon for hot melt transfer according to claim 1, which has a viscosity of 1 to 10,000 cps. 3. The ink ribbon for thermal melting transfer according to claim 2, wherein the porosity of the porous film is 90% or more. 4. The ink ribbon for thermal melting transfer according to claim 1, further comprising a conductive layer between the support and the ink layer.