JPH02192995A - Thermosensitive transfer medium capable of multiple rounds of printing - Google Patents

Abstract

PURPOSE:To make possible multiple rounds of printing with high sensitivity and print density and without character contamination by forming a fine porous resin layer as the first layer on a heat-resistant base, then forming a heat- melting transfer ink layer as the second layer, and adding a coloring agent made mainly of carbon black to both ink layers. CONSTITUTION:A fine porous resin ink layer 2 is formed on a heat-resistant base 1 as the first layer. The layer 2 contains a solid ink 5 consisting of a coloring agent of carbon black as a main constituent which is solid at normal temperature and thermally melts to be transferred in a fine porous resin layer 4 which is not transferred thermally. A melting, transferable ink layer 3 is formed on the layer 2 as the second layer. This layer consists of a solid ink 5 containing a coloring agent which is made mainly of carbon black. This carbon black does not contain a non-transferable constituent and thermally melts to be transferred. After initial printing with the second ink layer 3, new ink is supplied to the second ink layer 3 from the first ink layer whenever required for the second and following rounds of printing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel thermal transfer medium capable of melting and transferring ink multiple times by heating.

More specifically, it is used in recording devices such as thermal printers and thermal typewriters, and is capable of multiple printing that can be used many times by gradually transferring heat-melting ink to the recording paper by heating the thermal head. Related to thermal transfer media.

[Summary of the invention]

The present invention is a thermal transfer medium used in a recording device such as a thermal printer or a thermal typewriter, in which a first resin-based microporous ink layer is formed on a heat-resistant base material, and a second resin-based microporous ink layer is formed on the heat-resistant base material. By forming two heat-melting transferable ink layers and configuring both ink layers to contain a colorant whose main component is carbon black, it is possible to print multiple times.

[Conventional technology]

Thermal transfer media intended for multiple uses include heat-melting transfer ink in a microporous network structure disclosed in JP-A-54-68253, JP-A-55-105579, and JP-A-57-185191. Impregnated products are disclosed, and also disclosed in JP-A-57-160691 and JP-A-58-1832.
No. 97 discloses a method in which fine pores formed by non-transferable fine particles are impregnated with hot-melt ink.

In addition, there are those in which a non-transferable porous film is formed on the surface of a heat-melting solid ink layer, as disclosed in JP-A-60-40293 and JP-A-62.
-73994.

On the other hand, there is a technique in which an adhesive layer is provided between the base material and the ink layer to prevent the ink from being transferred all at once when heated with a thermal head.
No. 4, JP-A-58-116193, JP-A-58-15
No. 5995.

[Problem to be solved by the invention]

However, in a thermal transfer medium in which a fine porous layer formed of the resin and fine particles described above is impregnated with heat-melting ink, the amount of transfer ink per unit volume is small because the porous layer is non-transferable. The print density was low and the number of prints was also small. Furthermore, since the ink is retained in the microporous layer, it is difficult to dissolve, and therefore the initial print density is low, making it impossible to obtain clear prints with high density. In order to obtain dark prints, it was necessary to increase the film thickness, but increasing the film thickness further led to a lack of thermal sensitivity, resulting in a decrease in transfer efficiency, a decrease in the density of the transferred image, and an overload on the thermal head.
This caused a deterioration in the resolution of the printed image. In addition, it is difficult to control the diameter of the pores on the surface of heat-sensitive transfer media, in which a non-transferable porous film is formed on the surface of the heat-melting solid ink layer, and if the pores are too small, the amount of ink elution will decrease significantly, resulting in printing with low density. Put it away. In addition, if the diameter of the hole is too large, the ink will be eluted all at once, making it impossible to print multiple times.

On the other hand, attempts to prevent the ink from being transferred all at once by providing an adhesive layer between the base material and the ink layer have improved sensitivity, but the adhesive layer alone is sufficient to ensure a uniform ink transfer layer. It is difficult to control. As a result, a drawback was found that the print density decreased significantly with the number of times of use.

In view of the above-mentioned points, the present invention has high sensitivity and high printing density.
To provide a thermal transfer medium which is free from character smearing, has good print quality, and can be printed many times.

[Means to solve the problem]

As shown in Fig. 1, the present invention has a heat-resistant substrate (1) on which a resin-based microporous layer (4) that is not transferred by heat contains carbon black, which is solid at room temperature but melts and transfers by heat, as the main component. A first resin-based microporous ink layer (2) containing a solid ink (5) containing a coloring agent is formed, and carbon black, which does not contain a non-transferable component and is melted and transferred by heat, is formed thereon. A second heat-melting transferable ink layer (3) made of a colorant-containing solid ink (5) containing as a main component is formed to constitute a thermal transfer medium (6) that can be printed multiple times.

To be more specific, a total of 3 to 2
Form an ink layer with a thickness of 0 μm, and extend the ink layer with a thickness of 2 to 15 μm.
It is formed from two layers: a first layer of resin-based microporous ink layer (2) consisting of 0.2 to 15 μm, and a second heat-melting transferable ink layer (3) of 0.2 to 15 μm, with high sensitivity, To constitute a heat-sensitive transfer medium that can be used many times and has high printing density, no smudging of characters, and good printing quality.

In the thermal transfer medium (6) of the present invention, in order to firmly hold the non-transferable porous layer (4) of the first ink layer (2) and the base material (1), there is a gap between the ink layer and the base material. An adhesive layer can be formed as necessary. Further, a heat-resistant layer may be provided on the base material opposite to the ink layer.

The resin components forming the non-transferable resin microporous layer (4) in the first ink layer 0 of the present invention include polyvinyl chloride, polyvinyl acetate, polyvinyl fluoride, polyvinyl butyral, vinyl chloride. vinyl acetate copolymer,
Vinyl resins such as vinyl chloride/vinylidene chloride copolymer, vinyl chloride/acrylic ester copolymer, polyacrylic ester, polymethacrylic ester,
Acrylic resins such as acrylic acid ester/styrene copolymer, cellulose resins such as ethyl cellulose and cellulose ethyl acetate, other polystyrene, polyethylene, polyethylene/vinyl acetate copolymer, polyamide, ABS resin, gelatin, gum arabic, etc. be. These resins may be used in combination.

The solid ink (5) that melts with heat includes a solid component that is immiscible with the resin component, a flexibility imparting agent component that gives the ink a melting point adjustment effect and flexibility, a colorant component, and other fillers. It consists of a drug.

The solid components immiscible with the resin component include paraffin wax, microcrystalline wax, ceresin wax, carnauba wax, montan wax, polyethylene wax, oxidized polyethylene wax, castor wax, hardened tallow oil, carbowax, wood wax, and lanolin. , stearic acid, stearic acid monoglyceride, sorbitan monostearate, sorbitol hexastearate, pentaerythritol stearate, polyoxyethylene monostearate, stearyl alcohol, other synthetic oxidized waxes, synthetic and natural ester waxes, hydrogenated waxes etc.

Ink softener ingredients include mineral oil, petrolactam, oleic acid, castor oil, cottonseed oil, cow leg oil, octyl alcohol, glycerin, triethylene glycol,
Examples include polyalkylene glycol and its derivatives, polyoxyalkylene glycol and its derivatives, sorbitan fatty acid ester, sorbitol fatty acid ester, glycerin fatty acid ester, erythritol fatty acid ester, pentaerythritol fatty acid ester, polyoxyethylene alkylamine, and the like. In addition, resins that are compatible with the above-mentioned solid components are also used as softening agents.

As the colorant component, carbon black is the main colorant component, and if necessary, up to 70% by weight of the coloring component can be a commonly used dye, pigment, or other substance capable of coloring and recording, such as a basic dye, It was replaced with Zapon dye, Neozapon dye, Lake Rad, alkali blue navy blue, crystal violet lactone, magnetic iron oxide, etc.

If it exceeds 70% by weight, clear and high-density printing cannot be obtained.

Other fillers include ingredients that do not melt with heat and do not have coloring properties, such as silica powder, calcium carbonate, talc,
Examples include aluminum oxide. These components may be used alone or in combination.

The hot-melt transfer ink that is solid at room temperature used in the second ink layer (3) of the present invention refers to the heat-melt transferable ink that is solid at room temperature.
) is basically the same as the solid ink component that melts due to heat.

The ink composition of the heat-melting solid ink of the present invention is not particularly limited, but preferably the solid component immiscible with the resin component is 50 to 97 parts, and the softener component is 0 to 97 parts.
30 parts, colorant component 3-40 parts, other fillers 0
~20 parts is desirable.

In the heat-sensitive recording medium of the present invention, the resin component forming the non-transferable resin-based microporous layer of the first ink component and the solid ink component that is melted and transferred by heat are mixed in a suitable dispersion machine such as a ball mill or a sand mill. An ink prepared by dispersing it in an organic solvent or water is applied onto a heat-resistant substrate to a predetermined thickness and dried to form a first ink layer [2]. A second ink layer (3) is completed by applying an ink solution of a second ink component prepared in the same manner thereon, drying it, and forming a second ink layer (3) made of a solid ink that can be melted and transferred by heat.

[Effect]

In the thermal transfer medium of the present invention, since the second ink calendar (3) that contributes to initial printing is a heat-melting transferable ink that does not have a non-transfer component, the amount of transfer ink per unit volume is maximum, and the porous Since ink elution is not obstructed by the layer, initial printing with high sensitivity, resolution, and density is possible. Also, the first layer of resin-based microporous ink layer (2)
supplies new ink at any time for the second and subsequent printing of the heat-melting transferable ink layer (3) of the second layer, making it possible to print clearly multiple times, and at the same time, the second ink N (3) is completely transferred. By continuing to supply completely molten ink onto the recording paper, which receives sufficient heat from the thermal head,
It is possible to print multiple times with clear density.

As mentioned above, in the prior art, the ink film thickness had to be increased in order to print multiple times, resulting in insufficient sensitivity and unclear initial printing. In order to solve this problem, it is necessary to increase the energy applied to the thermal head, which leads to a reduction in head life due to excessive load, sticking caused by damage to the base material, and a decrease in printing resolution.

On the other hand, when the ink layer was made thinner, the amount of transfer ink per unit volume was smaller, resulting in lower print density and fewer printing times. The present invention can completely solve these problems.

If the thickness of the ink layer of the present invention is thinner than 3 μm, the amount of ink transferred each time is small, making it impossible to print with high density, and also making it impossible to print multiple times. If it is thicker than 20μ, the heat of the thermal head will not be sufficiently transmitted to the ink surface, resulting in insufficient sensitivity. Furthermore, the thickness of the first ink layer (2) is 2 μm.
If it is thinner, the fine porous layer (4) will not be completely formed and the ink supply will not be sufficient during printing, making it impossible to print multiple times. In addition, since the ink is retained in the pores, the melted ink will elute and if the thickness exceeds 15 μm, the transfer efficiency will decrease and clear printing will not be possible. Moreover, if the thickness of the second ink layer (3) becomes thinner than 0.2 μm, the initial printing becomes thinner. If it is thicker than 15μ, the sensitivity of the ink surface will be insufficient, and the ink layer will not be able to control the uniform transfer of the ink (this will result in a significant decrease in density as the number of printings increases).

〔Example〕

Next, examples of the thermal transfer medium of the present invention will be shown.

Example-1 Composition of the first ink layer Vinyl chloride/vinyl acetate copolymer (manufactured by Denki Kagaku Kogyo Co., Ltd.) 1000100O 30 parts by weight Carnauba wax (manufactured by Kato Yoko Co., Ltd.) 25 parts by weight Wood wax (manufactured by Noda Wax Co., Ltd.) 10 parts by weight Lanolin 20 parts by weight of carbon black (MA-7 manufactured by Mitsubishi Chemical Industries, Ltd.) 15 parts by weight Using a sand mill, the above ink formulation was reduced to 10% by weight.
A solution for the first ink layer was prepared by dispersing the mixture in a mixture of methyl ethyl ketone and toluene in equivalent weight over 3 hours to form a uniform dispersion. This was applied to the opposite side of a 5μ polyester film whose back side had been treated with silicone so that the thickness after drying would be 3μ and dried to form a first ink layer.

Composition of the second ink layer Carnauba wax (manufactured by Kato Yoko Co., Ltd.) 50 parts by weight Wood wax (manufactured by Noda Wax Co., Ltd.) 25 parts by weight Carbon black (manufactured by Mitsubishi Chemical Industries, Ltd. 51^-7) 25 parts by weight The components of the ink layer are 5 times 1 with the above composition.
% in a mixture of toluene and ethyl alcohol (weight mixing ratio 1:2) over 3 hours.
A second ink calendar solution was made.

This second ink layer solution was applied onto the previously formed first ink layer and dried to obtain a 0.2 μm second ink layer. The heat-sensitive transfer medium thus obtained was slit into a width of 6.35 mm and wound into a roll to form a sample for evaluation.

Printing was performed on smooth thermal transfer paper using a Brother word processor (Picoword 5100) at a printing speed of 30 cps. This was rewound and the same spot was printed 5 times, and the reflection density of the printed part was measured using a microdensitometer (made by Abe Sekkei,
Measurement was carried out using Model 2405).

Example-2 The solution for the first ink layer prepared in Example-1 was coated and dried to form a first ink layer to a thickness of 5 μm after drying, and then Example- A second ink layer solution of No. 1 was applied and dried to form a second ink layer with a thickness of 1 μm. after that,
A sample was prepared in the same manner as in Example 1, and the reflection density was measured.

Example 3 The same solution for the first ink layer as in Example 1 is applied so that the thickness after drying is 6 μm, and dried to form the first ink layer.

Composition of the second ink layer Carnauba wax (manufactured by Kato Yoko Co., Ltd.) 40 parts by weight Wood wax (manufactured by Noda Wax Co., Ltd.) 20 parts by weight Lanolin (manufactured by Yoshikawa Oil Co., Ltd.) 10 parts by weight Candelilla wax (manufactured by Kato Yoko Co., Ltd.) 20 parts by weight Carbon Black (MA-7 manufactured by Mitsubishi Chemical Industries, Ltd.) 20 parts by weight 10% by weight of the components of the second ink layer in the above formulation
A solution for the second ink layer was prepared by dispersing it in a mixed solution of toluene and ethyl alcohol (weight mixing ratio 1:2) to form a uniform dispersion. This second ink solution was applied onto the first ink layer to a thickness of 2 μm after drying and dried to prepare a thermal transfer medium.

This sample was printed in the same manner as in Example-1, and the reflection density was measured.

Example 6 Using ink with the same formulation as in Example 3, a sample was prepared by coating and drying so that the first ink layer had a thickness of 5 μ and the second ink layer had a thickness of 15 μ. However, the solution for the second ink layer was (Coated at a concentration of 20% by weight), printed in the same manner as in Example-1,
Reflection density was measured.

Example-4 The same ink as in Example-3 was used, and the first ink layer was 8μ,
A sample was prepared by coating and drying so that the second ink layer had a thickness of 4μ, and was printed in the same manner as in Example-1, and the reflection density was measured.

Example 5 Using ink with the same formulation as in Example 3, a sample was prepared by coating and drying so that the first ink layer had a thickness of 15 μ and the second ink layer had a thickness of 1 μ. However, the concentration of the solution for the second ink layer was is 5% by weight
Printing was performed in the same manner as in Example 1, and the reflection density was measured.

Comparative Example-1 Using the solution for the first ink layer of Example-1, it was coated and dried to a thickness of 10 μm after drying to create a thermal transfer medium with a microporous ink layer. did. This sample was printed in the same manner as in Example 1, and the reverse density was measured.

Comparison row-2 Polyvinyl butyral resin (manufactured by Denki Kagaku Kogyo Co., Ltd. “300”
0k) was dissolved in a mixed solvent such as toluene and ethyl alcohol to prepare a 5% solution. This was applied to the opposite side of a 5μ polyester film whose back side had been treated with silicone and dried to form a 0.7μ adhesive layer. On the other hand, a hot-melt ink was prepared by dispersing the following composition at 120° C. for 5 hours using a sand grinder.

Ink composition Carbon black (M^-7, manufactured by Mitsubishi Chemical Industries, Ltd.) 20 parts Paraffin wax ('155, manufactured by Nippon Seiro Co., Ltd.) 30 parts
30 parts carnauba wax (manufactured by Kato Yoko Co., Ltd.) 10 parts wood base (manufactured by Noda Wax Co., Ltd.) 10 parts ethylene/vinyl acetate copolymer (manufactured by Denki Kagaku Kogyo Co., Ltd.)
10 parts of 1000100O This ink was hot-melt coated on the adhesive layer to form a 10μ
A thermosensitive recording medium having a film thickness of 100 ml was prepared, a sample was prepared in the same manner as in Example 1, and the reverse density was measured by printing.

The above results are shown in Table 1. As a result, by forming the second layer with a heat-melting transferable ink that does not have non-transferable components, a new thermal transfer medium with high initial print density, high resolution, and which can be printed multiple times can be obtained. Became.

Table 1 [Effects of the Invention] According to the thermal transfer medium of the present invention, the ink has a two-layer structure consisting of a first resin-based microporous ink layer and a second heat-melting transferable ink layer thereon. By having the second ink layer, after the initial printing using the second ink layer, newer ink is supplied from the first ink layer to the second ink layer at any time for subsequent printing. Therefore, it is possible to print multiple times with high sensitivity, high print density, no character smear, and good print quality.

Therefore, it is suitable for use as a thermal transfer medium for recording devices such as thermal printers and thermal typewriters.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of the thermal transfer medium of the present invention. (1) is the base material, (2) is the first layer of resin-based microporous ink layer, (3) is the second layer of hot melt transfer ink layer, (4) is the resin-based microporous layer, (5) ) is a heat-melting transferable solid ink, and (6) is a heat-sensitive transfer medium that can be printed multiple times. Deputy Hide Mori Hitomatsu Kuma!・-・Fire resistance material 2-1. No.-Eyebrow n84 Greasy Nail Fine Hole Ink J3・--
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Claims (1)

[Scope of Claims] A first resin-based microporous ink layer is formed on a heat-resistant base material, a second heat-melting transferable ink layer is formed thereon, and both of the ink layers A thermal transfer medium capable of multiple printing, characterized in that it contains a colorant whose main component is carbon black.