JPH09263060A - Thermal transfer recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal recording medium good in printing quality by using wax having sharp meltability and excellent solubility as a heat meltable binder. SOLUTION: As a heat meltable binder being one of constitutional components of a thermal transfer recording medium, mol.wt. fractionated wax obtained by fractionating raw material wax by distillation or crystallization is used. This wax is characterized by that crystal melting peak temp. at a time of a temp. rise measured by a differential scanning calorimeter(DSC) is 55-12 deg.C and the difference between the crystal melting start temp. and crystal melting terminal temp. in a crystal melting pattern is 5-30 deg.C and melting energy is 100-250J/g.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thermal transfer recording medium using a wax obtained by molecular weight fractionation of a raw wax.

[0002]

2. Description of the Related Art Conventionally, the composition of a thermal transfer recording medium has been such that a pigment or dye as a coloring component is mixed with waxes or resins as a heat-fusible binder and, if necessary, dispersed in water or an organic solvent. It is prepared by adding an emulsifier or the like to supplement the properties.

Among the thermal transfer media, the wax as a heat-meltable binder is conventionally a petroleum wax such as paraffin wax and microcrystalline wax, a mineral wax such as montan wax, an animal and vegetable wax such as beeswax and carnauba wax, and polyethylene. Synthetic waxes such as wax and Fischer-Tropsch wax have been used, but these waxes do not have a sharp melting property and their solubility in a solvent is not always good, so that a recording agent in which a colorant is uniformly dispersed is used. A medium was not obtained, and accordingly, the print quality was not good, and none of them was always satisfactory.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the conventional wax as a heat-meltable binder in the thermal transfer medium, has a sharp melting property and dissolves in a solvent. Another object of the present invention is to provide a thermal transfer recording medium having good printing quality by using a wax having excellent properties as a heat-fusible binder.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, the present inventor has conducted distillation or crystallization (distillation and / or crystallization) from a raw wax in the production of a thermal transfer recording medium. By using the separated molecular weight fractionated wax as a heat-meltable binder, a thermal transfer recording medium having sharp melting behavior and excellent solubility in a solvent has been completed.

The thermal transfer recording medium of the present invention includes a thermal transfer recording medium having a heat-meltable color ink as a transfer layer, a thermal transfer recording medium having a transfer layer containing a leuco dye, and a heat sublimable or heat vaporizable dye. Naturally, a thermal transfer recording medium having a layer as a transfer layer is exemplified.

In both cases, the heat-soluble coloring ink layer as the transfer layer, the transfer layer containing the leuco dye, and the heat-sublimable or heat-vaporizable dye layer contain the heat-meltable binder, but the heat-meltable binder as the transfer layer. When the colored ink layer is used, the material to be transferred may be paper including synthetic paper, plastic film, or the like. Further, in the case of the type containing a leuco dye, a phenol resin, an organic acid, an organic acid ester or the like is used as a main component of a leuco dye developer on a support such as a paper including a synthetic paper as a material to be transferred or a plastic film. A sheet provided with an electron-accepting material layer is used.

The thermal transfer recording medium of the present invention is particularly suitable for a thermal transfer recording medium having a thermally fusible colored ink layer as a transfer layer. In that case, the heat-meltable colored ink layer is composed of a color ink pigment and a heat-meltable binder.

As the colored ink pigments, black ink such as carbon black, pigments such as phthalocyanine blue, iodine red and brilliant green, dispersible monoazo dyes, dispersed anthraquinone dyes and the like, which are solid at room temperature, are used.

The molecular weight fraction wax in the present invention is
It is a wax in which only the wax component is extracted from the raw wax composed of the wax component and other impurities, and the one having the desired molecular weight distribution is selectively extracted. A wax with a sharp melting behavior and excellent solubility in solvents. Raw wax is a low-polymerization polyolefin, especially low-degree polyethylene wax,
It is a synthetic wax such as Fischer-Tropsch wax, coal-based synthetic wax, natural gas-based synthetic wax, and also includes petroleum-based paraffin wax and natural wax.

As the heat-meltable binder, this molecular weight fractionated wax is used. As means for selectively extracting one having a desired molecular weight distribution, distillation or crystallization from the raw material wax, that is, distillation and crystallization or either Separate on the other hand. Among the molecular weight fractionated waxes obtained by fractionation, those used in the present invention include differential scanning calorimeters (D
Range of crystal melting peak temperature at temperature rise measured by SC)
(Hereinafter abbreviated as melting peak temperature range) is 55 ~ 120 ℃, preferably 65 ~ 120 ℃, more preferably 65 ~ 85 ℃, the difference between the crystal melting start temperature and the crystal melting end temperature in the crystal melting pattern (hereinafter melting temperature The width) is 5 to 30 ° C., and the melting energy is 100 to 250 J / g.

When the melting peak temperature range is lower than 55 ° C., the printability becomes poor, and when it is higher than 120 ° C., the solubility (in the solution coating method) becomes insufficient, and the transferability becomes unfavorable. If the melting temperature range is lower than 5 ° C, the printed layer tends to become brittle. If the temperature is higher than 30 ° C, the printability and transferability will be undesired. Melting energy is 10
If it is lower than 0 J / g, scratch resistance will be poor. If it is higher than 250 J / g, the transferability is not good.

The blending amount of this molecular weight separation wax is
It is 50 to 400 parts by weight, preferably 100 to 300 parts by weight, per 100 parts by weight. If it is less than 50 parts by weight, the scratch resistance will be poor, and if it is more than 400 parts by weight, the printability and transferability will be poor.

If necessary, polyethylene, polypropylene, polyvinyl chloride, polyvinyl acetate, polystyrene, polyacrylic acid ester, ethylene vinyl acetate copolymer, epoxy resin, petroleum resin, terpene resin, coumarone / indene resin, etc. In addition to the thermoplastic polymer, a rubber-like polymer such as nitrile rubber, styrene / butadiene rubber, ethylene / propylene rubber can be blended.

Further, a softening agent such as oil, a radical polymerization inhibitor, and an ultraviolet absorber for improving weather resistance can be used in combination.

The heat-fusible color ink is applied on a plastic film such as polyester or a base film such as paper at an application amount of 1 to 50 g per 1 m ² by a hot melt coating method, a solution coating method or an emulsion coating method. .

For recording with the coated heat-fusible colored ink layer, a thermal transfer printer is used to obtain a printed matter as a bar code or the like.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The thermal transfer inks of Examples and Comparative Examples shown below were blended according to the basic formulation shown in Table 1.

[0019]

[Table 1]

Regarding the wax components in the basic formulation of Table 1, the wax components of the examples and comparative examples shown in Table 2 below were used to prepare thermal transfer inks.

[0021]

[Table 2]

The wax component used in Examples 1, 2 and 4 was a low molecular weight wax called Ziegler synthetic wax which was distilled.
Molecular weight fractionation was carried out by crystallization operation, and Examples 3 and 5 were obtained by distilling Ziegler synthetic wax. The measurement results of these GPC (gel permeation chromatograph) are shown in Table 2 at the same time. Examples 1, 2,
The distillation-crystallization operation of No. 4 is as follows. In the example of Example 2, first, a Ziegler synthetic wax was distilled into a wax at a film evaporator of 0.05 mmHg and 290 ° C., and
Add 3 times the amount of methyl isobutyl ketone to the wax,
After heating and melting, the temperature was lowered to 50 ° C. to precipitate crystals, which were separated by filtration.
Distillation distillation temperatures in Examples 1 and 4 were 270 ° C and 300 ° C, respectively.
It is. The temperature at which the temperature of the wax distilled out after dissolution of the solvent was 40 ° C. and 55 ° C., respectively.

The waxes used in Examples 3 and 5 were obtained by the distillation operation (distillation distillation at 293 ° C. in Example 3 and 255 ° C. in Example 5).

Example 6 was obtained by a crystallization operation. Methyl isobutyl ketone was added to the wax in an amount of 3 times, and after heating and dissolution, 89
It was obtained by lowering the temperature to ℃.

The wax component of Comparative Example 1 was obtained by distilling Ziegler synthetic wax at 240 ° C. The wax component used in Comparative Example 3 was obtained by adding Ziegler synthetic wax in an amount of 3 times the amount of methyl isobutyl ketone, heating and melting the mixture, and then lowering the temperature to 93 ° C. The wax of Comparative Example 2 is a low-molecular-weight polyethylene called Ziegler synthesis, which was used as a raw material for Examples of the present invention and other Comparative Examples.

The solubility of the wax in the solvent due to the difference in the wax components of the examples and the comparative examples, and the printability after the thermal transfer ink was applied and dried on the polyethylene terephthalate film were evaluated by the transfer probability and the high-speed printability. Table 3 shows the results.

[0027]

[Table 3]

Solubility in a solvent is 10% toluene at 70 ° C.
100 parts by weight of wax is melted against 0 parts by weight to make transparency excellent
Slight cloudiness was acceptable, cloudiness was acceptable, and haze was not observed.

As for the transfer probability, an image point composed of 4 × 4 dots is printed at a paper feed speed of 5 cm / min, and the number of 90% or more of the regular image point size is observed. Expressed as a percentage.

The high-speed printability was expressed in percentage by the same evaluation method as the transfer probability evaluation, and the transfer probability when printed at a paper feed speed of 300 cm / min. The overall evaluation was judged by the evaluation including stains and scratches on the printed matter.

[0031]

INDUSTRIAL APPLICABILITY Since the present invention makes it possible to use a wax that meets the required performance as a heat-meltable binder, not to mention a heat-sensitive transfer recording medium having a heat-meltable colored ink as a transfer layer, It is now possible to provide various thermal transfer recording media that meet the requirements.

Claims (2)

[Claims] 1. A thermal transfer recording medium, characterized in that a molecular weight fractionated wax fractionated by distillation or crystallization from a raw material wax is used as a heat-meltable binder which is one of the constituent components of the thermal transfer recording medium. 2. The raw material wax according to claim 1 is a synthetic wax, and the molecular weight fractionation wax is a differential scanning calorimeter (D).
The temperature range of the crystalline melting peak measured by SC) is 55 to 120 ° C, the difference between the crystalline melting start temperature and the crystalline melting end temperature in the crystalline melting pattern is 5 to 30 ° C, and the melting energy is 100. Thermal transfer recording medium of ~ 250 J / g.