JP3142178B2 - 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 an ink ribbon for hot-melt transfer suitable for multi-time printing. More specifically, the present invention uses a specific ink,
The present invention relates to an ink ribbon for hot-melt transfer in which a decrease in print density during multi-time printing is reduced.

[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 in accordance with image information, and ink is transferred from the ink ribbon to a transfer target such as recording paper. Hot-melt transfer recording, in which ink is sometimes melt-transferred from an ink ribbon to an object to be transferred, is widely used.

By the way, as an ink ribbon, conventionally,
Once used for thermal transfer recording, all of the ink layer at that portion is transferred to the transfer-receiving member, so that it is a one-time use that cannot be used repeatedly. However, in recent years, a multi-time ink ribbon that can be used repeatedly many times has been desired, and its development has been attempted. For example, as a multi-time ink ribbon, the ink layer is formed by sequentially laminating an ink and a resin in which a filler is dispersed in a layer, and at the time of transfer, the ink layers formed in layers are transferred one by one. It has been proposed that this be done. Further, as a more preferred embodiment, the ink is formed by holding the ink in a porous resin layer, and the ink in a molten state is partially transferred 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, a resin in which fillers such as beads and carbon are dispersed, and a resin having a different property are mixed, and the mixture is applied to a base material, cured, and then mixed. A resin obtained by dissolving and removing only the above resin with a solvent is known. Further, it is also known that a resin is dissolved in a volatile solvent such as toluene, xylene, methyl ethyl ketone, and the like, and the resulting solution is applied to a base material, and then dried to remove the volatile solvent to make the porous material porous. .

[0004]

However, even if a conventional multi-time ink ribbon in which ink is held in a porous resin is used, there is a problem that a large number of times of repetitive printing cannot be performed satisfactorily. Was. That is, conventionally,
It is difficult to form a uniform and high porosity porous resin layer for use in multi-time ink ribbons, which makes it impossible to hold a sufficient amount of ink in the pores, resulting in poor print quality. Had been reduced. 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 printing is repeated many times, and good print quality cannot be maintained.

An object of the present invention is to solve the above-mentioned problems of the prior art, and an ink ribbon for hot-melt transfer capable of maintaining good print quality even when repeatedly used for transfer many times. It is intended to provide.

[0006]

Means for Solving the Problems The present inventors have formed an ink layer of an ink ribbon used for hot-melt transfer recording by holding ink on a porous film and further increasing the viscosity of the ink. Was found to be effective, and the present invention was completed.

Namely, this invention has a support and an ink layer, the ink layer is, the porous film of a porosity of 90% or more, the viscosity is 120 ° C. of 1000-5000
3000 to 10,000 at 80 ° C.
Provided is an ink ribbon for hot-melt transfer, characterized by holding cps ink .

Hereinafter, the present invention will be described in detail with reference to the drawings.

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

Here, it is preferable to use a support made of a heat-resistant resin such as aramid, polyimide or the like so that the support 1 does not thermally shrink by transfer and can withstand multiple transfers. When an energized heat-sensitive printer is used, a conductive support made of a heat-resistant resin such as conductive aramid containing carbon in aramid is preferably used as the heat-resistant support.

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 an evaporation film. Moreover, you may laminate | stack through an adhesive agent. The conductive layer 2 is not always necessary in the ink ribbon of the present invention, but is provided when a current-sensitive type printer is used. In this case, the conductive layer 2 is formed to have an appropriate thickness (about 500 to 1000 Å) so that the current density in the conductive layer 2 does not become excessively high and current does not easily flow. As a result, it is possible to improve the heat generation efficiency when transferring by the energized heat-sensitive method.

On the other hand, when using a printer having a normal thermal head which is not of the energized heat-sensitive type, the conductive layer 2 is not formed as described above, and the ink ribbon is attached to the above-mentioned 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 even in this case, in order to efficiently transfer the heat of the thermal head to the ink layer.

In the present invention, as the ink layer 3,
Use a porous film in which ink is held. As the porous film, a resin such as polytetrafluoroethylene (PTFE), polypropylene, polyester, or high-density polyethylene is used.
% Is preferably used. In particular, a film obtained by biaxially stretching 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 vacancies, and it is possible to improve transferability by repeating the film many times. In addition, when the porosity is low, since the matrix of the film is dense, the pigment of the ink such as carbon black is blocked by the matrix of the film, and it is difficult to transfer to the transfer target, and the transfer density is reduced. However, when the porosity is increased, such a decrease in the transfer density can be prevented.

The ink may be retained in the porous film by impregnating the pores of the film with the ink by a conventional method.

In the present invention, the ink held on the porous film as described above has a viscosity of 12
A material having a high viscosity of 1000 to 5000 cps at 0 ° C. is used. 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 every transfer, and even though a sufficient print density is obtained in the first to third transfer, the print density decreases in the fourth and subsequent transfer. However, good print quality cannot be obtained. On the other hand, if the viscosity of the ink is higher than the above range, the amount of melt transfer at the time of transfer decreases, and a sufficient print density cannot be obtained. The method of adjusting the viscosity of the ink to such a viscosity can be achieved by appropriately changing the compounding ratio of the components of the ink, and the compounding components of the ink itself can use the same coloring agents, binders, and softeners as those of the conventional ink.

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

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 and ester derivatives thereof can be used.

Examples of the softener include 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. can do.

[0019]

According to the ink ribbon of the present invention, since the ink layer is formed from a porous film holding the ink, a sufficient amount of the ink can be held in the ink layer. Further, as the ink in this case,
Its viscosity is 1000-5000 cps at 120 ° C
High viscosity, the amount of ink that is melt-transferred onto the transferred material can be suppressed to an appropriate amount for each transfer, so that even if printing is repeated many times, high print density and good print quality can be achieved. It can be sustained.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments.

Example 1 An ink ribbon having a layer structure shown in FIG. 1 was prepared. In this case, a conductive aramid film (3.6 kΩ / □) having a thickness of 10 μm (manufactured by Toray Industries, Inc.) is used as the support 1, and a 1000 Å-thick aluminum vapor-deposited film 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 and impregnated with ink was formed. In this case, an ink having the following ink composition and ink characteristics was used.

(Ink composition) Carbon black 20% by weight Paraffin wax (manufactured by Nippon Seiro Co., Ltd., HNP-3WAX) 48% by weight Carnauba wax (manufactured by Toyo Petrolite) 20.5% by weight Softener: EVA 7.5% by weight % Dispersant: MEK 4% by weight (Ink properties) Melting point 65 ° C Viscosity 3000 cps / 80 ° C 1000 cps / 120 ° C Also, as an adhesive between the conductive layer 2 and the ink layer 3, an adhesive having the following composition having a thickness of 1 ３3 μm was used and gripped.

(Adhesive composition) Acrylic pressure-sensitive adhesive 39.7% by weight (Polysic 410-SA, manufactured by Sanyo Chemical Co., Ltd.) 0.8% by weight of polyisocyanate (Polysic 410-, manufactured by Sanyo Chemicals, Inc.) SC) Ethyl acetate 59.5% by weight Examples 2 to 5 and Comparative Examples 1 to 3 An ink ribbon was prepared in the same manner as in Example 1 except that inks having the composition ratios and characteristics shown in Table 1 were used.

[0024]

[Table 1] Example Comparative Example 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 properties) Melting point (° C) 65 65 65 65 65 65 65 65 Viscosity 80 ° C (cps) 3000 3910 3660 4680 8300 170 651 37000 120 ° C 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 an energized thermal transfer printer under the following printing conditions. Reflection density O. D. Is a densitometer (manufactured by McBeth,
RD-918). The result is shown in FIG. In this case, the reflection density O.D. D. FIG. 3 shows the relationship between the number of prints that can print 1 or more and the ink viscosity.

(Print conditions) Serial head (recording electrode) Tungsten (φ0.06), 0.125 pitch, 32 return electrodes Stainless steel (φ2) Distance between electrodes 37 mm Printing speed 19.6 cps (character size 4)
× 4) Print voltage 0.22 to 0.5 mJ / dot Print pattern Solid black, font As is clear from FIGS. 2 and 3, 1 at 120 ° C.
The ink ribbon of the example of the present invention using an ink having a viscosity of 000 to 5000 cps was excellent in multi-time printability.

[0026]

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

[Brief description of the drawings]

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

FIG. 2 shows the number of printings and the reflection density of a printed matter when the ink ribbons of Examples and Comparative Examples are used. D. FIG.

FIG. 3 shows the reflection density of a printed matter when the ink ribbons of Examples and Comparative Examples are used. D. FIG. 6 is a diagram illustrating the relationship between the ink viscosity and the number of times of printing when is equal to or more than 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support 2 Conductive layer 3 Ink layer 10 Ink ribbon

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Takashi Murayama 18th Satsuki-cho, Kanuma-shi, Tochigi Sony Chemical Corporation Kanuma Plant (56) References JP-A-55-105579 (JP, A) JP-A-4-4 16386 (JP, A) JP-A-2-273278 (JP, A)

Claims (3)

(57) [Claims] [Claim 1 further comprising a support and an ink layer, the ink layer is, the porous film of a porosity of 90% or more, viscosity 1
1000-5000 cps at 20 ° C. and 8
Store 3000 to 10000 cps ink at 0 ° C.
An ink ribbon for hot-melt transfer, characterized in that it is held . Wherein the ink layer, the ink in the porous film
The ink ribbon for hot melt transfer according to claim 1, wherein the ink ribbon is laminated on a support after being impregnated . 3. The ink ribbon for hot-melt transfer according to claim 1, wherein the porous film is formed by a stretching method.