JPH042438B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thermal transfer ribbon used in a printing device such as a thermal printer that performs printing by thermal transfer.

[Prior art] Printing using a thermal transfer ribbon is performed by bringing the thermal transfer ribbon into close contact with printing paper using a thermal head, and by causing a desired heating element among the many heating elements of the thermal head to generate heat, the thermal transfer ribbon is attached to the heating element. This is done by melting the heat-melting ink portion that is in contact with the support through the support and transferring it to the printing paper.

Conventionally, this type of thermal transfer ribbon has simply been coated directly onto a support with a heat-melting ink consisting of a colorant and a binder agent, and the binder agent has been mainly composed of wax.

[Problems to be Solved by the Invention] However, when printing is performed on plain paper using a thermal transfer ribbon that is simply coated with heat-melting ink directly onto a support as described above, the smoothness of the plain paper is Sufficient print quality could not be obtained unless the printing time was maintained for several tens of seconds at a certain temperature.

The reason for this is that when the surface smoothness of the printing paper is low, as shown in Figure 2, the hot melt ink cannot come into contact with the recesses on the surface of the printing paper, and the ink transfer is not achieved, resulting in blurred printing. This is caused by the occurrence of gaps or omissions.

One possible way to solve this problem is to significantly lower the melt viscosity of the heat-melting ink, allowing the ink to penetrate from the contact areas of the convex parts of the printing paper and reach the non-contact parts of the concave parts. Such ink penetration occurs even in areas where the ink should not be transferred, making the outline of the transferred image unclear and giving it a smeared appearance.

[Object of the Invention] The present invention was made in order to solve the problems of the conventional thermal transfer ribbon as described above, and its purpose is to keep the printing energy within the range that can be sufficiently realized with the conventional thermal head. To provide a thermal transfer ribbon that can print clearly without fading or missing even on non-smooth printing paper.

[Means for Solving the Problems] In order to achieve the above object, in the thermal transfer ribbon of the present invention, a release layer is interposed between the film-like support and the heat-melting ink layer, and the The meltable ink layer is formed of a heat-meltable ink obtained by mixing a coloring agent and a binder agent whose main components are a ketone resin and an ethylene-vinyl acetate copolymer resin.

[Function] According to the above structure, the heat-melting ink melted by the heat from the thermal head at the contact point of the convex portion of the printing paper during printing is sufficiently fixed, and when the thermal transfer ribbon is peeled off, it is firmly attached to the support and the release layer or release layer. Since the cohesive force of the thermofusible ink itself is greater than the adhesive force between the paper and the thermofusible ink, the thermofusible ink in the non-contact areas corresponding to the recesses of the paper is also peeled off and transferred to the same paper. be able to.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

In FIG. 1, a thermal transfer ribbon 10 has a release layer 12 formed on a film-like support 11, and a heat-melting ink layer 13 further formed thereon.

Film-like support 1 used in this example
1 is polyester with a heat-resistant temperature of 150℃ or higher,
Examples include films made of polyimide, polycarbonate, polysulfon, polyether sulfon, polyphenylene sulfide, polyether-ether ketone, etc., and papers such as capacitor paper and glassine paper, and the thickness thereof ranges from about 3 to 20μ. It is desirable to have one. Further, as shown in FIG. 1, a sticking prevention layer 14 made of a heat-resistant resin such as silicone resin is provided on the opposite side of the coated surface of the heat-fusible ink layer 13.

The heat-melting ink layer 13 is composed of a coloring material and a binder agent.

As the coloring agent, inorganic or organic pigments such as carbon black, lake red, alkali blue, and navy blue, and oil-soluble or basic dyes that are highly soluble in fatty acids such as nigrosine, oil black, and methyl violet are used.

Note that dyes are added as auxiliary agents to produce colors that cannot be produced by pigments alone, or to adjust the tone.

In addition, as a binder agent, in order to increase the melt viscosity and the cohesive force of the heat-melt ink itself at the transfer stage compared to the heat-melt ink layer of conventional thermal transfer ribbons, a ketone resin that is not compatible with each other is used. paraffin wax, microcrystalline wax, oxidized paraffin wax, and Candelilla, which have a melting point of 40 to 100°C, and which have a melting point, melt viscosity, etc. as main components and ethylene-vinyl acetate copolymer resin. Wax, carnauba wax, montan wax, ceresin wax, polyethylene wax, oxidized polyethylene wax, castor wax, hydrogenated tallow oil, lanolin, wood wax, sorbitan stearate, sorbitan palmitate, stearyl alcohol, polyamide wax In addition to waxy substances such as wax, oleylamide, stearylamide, hydroxystearic acid, synthetic ester wax, and synthetic metal-containing wax, polyvinyl butyral, vinyl chloride-vinyl acetate copolymer resin, nitrocellulose, epoxy resin, ethylene-α Olefin copolymer resin, α-olefin
One or more resins such as maleic anhydride copolymer resin, ethylene-methacrylic acid copolymer resin, and ethyl cellulose may be mixed. and,
The colorant, ketone resin, and ethylene-vinyl acetate copolymer resin are 5 to 40 wt%, 20 to 80 wt%, and 10 to 50 wt%, respectively, based on the total amount of the hot-melt ink layer.
The combination of 15 to 20wt each
%, 50-55%, 15-25wt% is desirable.

Further, the release layer 12 is made of polyethylene wax, which has a low melt viscosity and poor affinity with hot-melt ink.

Note that polyethylene wax alone may be used as the release layer 12, but fillers such as bentonite, kaolin, and talc may be added to meet various requirements for the ink ribbon. Melting point viscosity etc. can be changed in a preferable direction.

Next, based on this example, a manufacturing process for forming a release layer 12 and a hot-melt ink layer 13 on a support 11 having an anti-staking layer 14 formed on the back side will be described.

(1) Release layer generation process Dilute polyethylene wax emulsion with water to make a coating liquid. In addition, when adding a filler, it is dispersed in the coating liquid using ultrasonic waves.

(2) Coating and drying process of release layer The coating solution is coated onto a film-like support 11, for example, a polyester film (thickness: 3.5 μm) using an appropriate coating device. Dry it at 80-100℃. In this example, the coating thickness was set to about 1 μm.

(3) Step of producing hot-melt ink A colorant and a binder agent whose main components are a ketone resin and an ethylene-vinyl acetate copolymer resin are dissolved or dispersed in a solvent. For dispersion, a commonly used dispersing machine such as a three-roll mill, sentry mill, sand mill, or ball mill is used.
This solution and dispersion liquid is used as an ink coating liquid.

(4) Coating and drying step of ink coating liquid The ink coating liquid is applied onto the film-like support 11 coated with the release layer 12 using the appropriate coating device. And then heat it to 80~100℃
Dry with. In this example, the coating thickness of the ink was set to 4 to 6 microns.

With the above steps, the structural process of the thermal transfer ribbon 10 is completed.
A thermal transfer ribbon 10 as shown in FIG. 1 is obtained.

Examples of the thermal transfer ribbon according to the present invention are shown below as Example 1 and Example 2.

Example 1 A Release layer a Release layer components...1 part by weight Polyethylene wax emulsion [Polylon #393 from Chukyo Yushi Co., Ltd.] 92.5 wt% Bentonite 7.5 wt% Total 100% b Diluent...1 part by weight Water 100wt% B Hot-melt ink layer C Ink components...1 part by weight Ketone resin [Ketone Resin K-90 from Arakawa Chemical Co., Ltd.] 55wt% Ethylene-vinyl acetate copolymer resin [Mitsui-Dupont Polychemical Co., Ltd.] Everflex 250]
25wt% polyvinyl butyral [Sekisui Chemical Co., Ltd.'s Eslec BM-S] 5wt% carbon black [Mitsubishi Chemical Corporation's MA-
7] 15wt% Total 100% d Solvent...3 parts by weight Methyl isobutyl ketone 100wt% The above component a is diluted with component b to obtain a coating liquid. This coating liquid is applied to a support 11 formed of a 3.5μ polyester film to a coating thickness of approximately 1 μm to obtain a release layer 12 on the support 11. An ink coating liquid consisting of component c and component d is applied onto this release layer 12 and dried at 80 to 100°C. Then, on the release layer 12 on the support 11, a thickness of 4 to 4
A thermofusible ink layer 13 having a thickness of about 6 μm is formed.

When the thermal transfer ribbon 10 produced in this way was used to print on printing paper with a Bekk smoothness of 4 seconds, the ink was also transferred to the concave portions of the printing paper, and the printed image was sharp and dark with very little fading. was gotten.

Here, based on FIG. 2, a description will be given of the process of transferring heat-melting ink when printing is performed on printing paper with low smoothness using the thermal transfer ribbon 10 according to the present invention.

A thermal head 15 presses a thermal transfer ribbon 10 against a printing paper 16 on a platen (not shown). Then, when the thermal head 15 generates heat,
Heat is conducted to the release layer 12 and the heat-melt ink layer 13 through the staking prevention layer 14 and the film-like support 11, and the release layer 12 and the heat-melt ink layer 13 are melted and applied to the convex portions of the printing paper 16. The hot-melt ink that is in contact adheres to (partially penetrates) the convex portion. Then, when the thermal head 15 stops generating heat, the heat-melting ink layer 13 is cooled and fixed to the printing paper 16. At this time, the heated part of the release layer 12 still maintains a liquid state, and the heat-melting ink layer 13 corresponding to this part has a strong cohesive force inside, but has poor adhesion to the release layer 12. Extremely poor (remarkably smaller than the adhesion between the heat-melting ink layer 13 and the release layer 12 in the non-heated portion).

Therefore, the heat-melting ink layer 13 in the heated portion, that is, the printed image portion, is easily transferred to the printing paper 16 side, including the portion (concavity) not in contact with the printing paper 16, as shown in FIG. At this time, the following relationship holds true.

F4>F1>F2>F3 F1: Adhesive force of the heat-fusible ink layer 13 to the printing paper F2: Cohesive force of the heat-fusible ink layer 13 at the boundary between heated and non-heated areas F3: Heat-fusible ink layer 13 and the release layer 12 or adhesion force between the release layer 12 and the support 11 F4: Cohesive force of the heat-melting ink layer 13 in the heated area. Printing with low smoothness is achieved by utilizing the large cohesive force of the adhesive ink itself and by utilizing the low melt viscosity of the polyethylene wax emulsion of the release layer 12 and poor affinity with hot-melt ink. High-quality printing is possible on paper with no scratches or the like.

In addition, the fact that the fine molecules of the ethylene-vinyl acetate copolymer resin are not compatible and scattered within the ketone resin is responsible for the sharpness of the heat-melting ink layer at the boundary between the heated part and the non-heated part, that is, It is thought that this contributes to the sharpness of printed characters.

Example 2 A Release layer a Release layer components...1 part by weight ●Polyethylene wax emulsion [Polylon A from Chukyo Yushi Co., Ltd.] 100wt% b Diluent...1 part by weight ●Water 100wt% B Heat-melt ink Layer c Ink component...3 parts by weight ●Ketone resin [Ketone Resin K-90 from Arakawa Chemical Co., Ltd.] 50wt% ●Ethylene-vinyl acetate copolymer resin [Mitsui Chemical Co., Ltd.]
Evaflex by Dupont Polychemical Co., Ltd.
210] 30wt% ●Carbon black [MA of Mitsubishi Chemical Industries, Ltd.
-7] 20 wt% Total 100% d Solvent... 7 parts by weight Methyl isobutyl ketone 100 wt% Printing was performed using the thermal transfer ribbon 10 manufactured in the same process as Example 1 with each of the above components.
Printing quality equivalent to that of Example 1 could be obtained.

Next, for comparison with the thermal transfer ribbon according to the present invention, typical thermal transfer ribbons made of other components are shown as Comparative Example 1, Comparative Example 2, and Comparative Example 3, respectively.

Note that these Examples differ only in the components of the heat-fusible ink layer, and the components of the release layer are common and are as described below.

[Common components] A Release layer a Release layer component...1 part by weight ●Polyethylene wax emulsion [ME-10 from Chukyo Yushi Co., Ltd.] 100wt% Comparative example 1 B Heat-melting ink layer c Ink component...1 Parts by weight ●Hydrogenated rosin [Hypere from Arakawa Chemical Co., Ltd.] 40wt% ●Ethylene-vinyl acetate copolymer resin [Mitsui
Evaflex by Dupont Polychemical Co., Ltd.
J441-2-1] 40wt% ●Carbon black [MA of Mitsubishi Chemical Industries, Ltd.
-100] 20wt% Total 100% d Solvent 4 parts by weight Toluene 100wt% When printing was performed on printing paper with a Beck smoothness of 4 seconds using the thermal transfer ribbon of Comparative Example 1, the transfer to the concave portions of the printing paper was insufficient. So, the scum was noticeable.

Comparative Example 2 B Hot-melt ink layer c Ink component...1 part by weight Ethylene-vinyl acetate copolymer resin [Mitsui
Evaflex by Dupont Polychemical Co., Ltd.
410] 80wt% ●Carbon black [MA of Mitsubishi Chemical Industries, Ltd.
-100] 20 wt% Total 100% d Solvent 4 parts by weight ●Toluene 100 wt% The printing condition was slightly better than that of Comparative Example 1, and some fading still occurred.

Comparative Example 3 B Hot-melt ink layer c Ink component...1 part by weight ●Ketone resin [Ketone Resin K-90 from Arakawa Chemical Co., Ltd.] 40wt% ●Polyamide [Sunmide #615A from Sanwa Chemical Industry Co., Ltd.] 40wt% ●Carbon black [MA of Mitsubishi Chemical Industries, Ltd.
-100] 20wt% Total 100% d Solvent ● Isopropyl alcohol 4 parts by weight The printing condition is good with few blurring, but the heat-melting ink layer is brittle and the film-like support can be rubbed with a finger even without applying heat. It may fall off the body.

[Effects of the Invention] As detailed above, in the thermal transfer ribbon according to the present invention, a release layer is interposed between the film-like support and the heat-melt ink layer, and the heat-melt ink layer is made of ketone. The resin and ethylene-vinyl acetate copolymer resin are formed from a heat-melting ink made by mixing a binder agent and a colorant as main components, and when printing, when the thermal transfer ribbon is peeled off, it is separated from the support. Because the cohesive force of the heat-melt ink itself is greater than the adhesive force between the release layer or the release layer and the heat-melt ink, the heat-melt ink in the non-contact areas corresponding to the recesses of the paper can be absorbed. It can be peeled off and transferred at the same time, making it possible to print clearly even on printing paper with low smoothness without scratches or omissions.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a thermal transfer ribbon showing an embodiment of the present invention, FIG. 2 is a cross-sectional view showing the state of transfer to printing paper by the thermal transfer ribbon, and FIG. 3 is a cross-sectional view showing the printing paper and the thermal transfer ribbon after printing. FIG. 10: Thermal transfer ribbon, 11: Support, 12: Peeling layer, 13: Heat-melting ink layer.

Claims (1)

[Scope of Claims] 1. A heat-melt ink formed by mixing a film-like support and a coloring agent and a binder whose main components are a ketone resin and an ethylene-vinyl acetate copolymer resin. 1. A thermal transfer ribbon comprising: a thermofusible ink layer; and a release layer interposed between the support and the thermofusible ink layer. 2. Claim 1, wherein the release layer is mainly composed of a wax having a low melt viscosity and poor affinity with the heat-melting ink.
Thermal transfer ribbon described in Section 1.