JP2584455B2 - Thermal transfer ink and ink film - Google Patents

Description

The present invention relates to a thermal transfer recording ink and an ink film. More specifically, the present invention relates to a thermal transfer recording method widely used in personal word processors and the like. It is intended to supply a multi-use thermal transfer ink ribbon for reducing the number of times.

[Conventional technology and its problems]

Thermal transfer type printers are widely used as small, lightweight and inexpensive popular printers. In particular, it is almost 100% adopted in the field of personal word processors, etc., taking advantage of its maintenance-free features.

As described above, the thermal transfer printing system has many advantages as a popular printer, but as thermal transfer printers become more widespread in the future, the cost of consumables will increase and the printing cost per sheet will increase. This is expected to be the biggest obstacle. The reason for this high cost is that cassettes must be supplied in a small quantity and large variety because of the need to supply cassettes for each model, and the price of cassettes and other peripheral parts other than the original consumables is lower than that of ribbons. And it is difficult to automate a series of post-processing such as slitting, core winding and cassette stuffing, which increases labor costs and increases distribution costs.

[Means for solving the problem]

In view of the above problems, the present inventors have conducted intensive studies with the aim of supplying consumable materials for a thermal transfer printer that realizes low printing cost by using the same ink ribbon many times, and as a result, the present invention It has been reached.

That is, the present invention has a melting point (JIS-K0064) of 55 ° C to 110 ° C.
A resin having a melt viscosity at 120 ° C. of 10,000 cps or less, and a solidification point (JIS-K0065) lower than the melting point of 5 ° C. or more,
And a thermal transfer ink capable of multi-printing characterized by containing a coloring agent as an essential component, and a multi-printing sensitive ink characterized by applying the ink to one surface of a support. An object of the present invention is to provide an ink film for thermal transfer.

The thermal transfer printing system uses a thermal head to heat and melt the heat-meltable ink applied on a base film such as polyethylene terephthalate (PET) film from the back side of the base film, so that it permeates or adheres to the paper to be transferred. This is a system in which ink is transferred from the base film side to the transfer paper side by mechanically separating the film and the transfer paper. When the conventional ink ribbon is used, the ink is cooled and solidified at the time of peeling, so that the entire amount of the heated and melted ink is transferred to the transfer receiving paper, resulting in a disposable ink ribbon that can be used only once. However, when using the ribbon made of the ink film of the present invention, there is a difference in the melting point and the freezing point of the ink,
The ink remains in a molten state even when the film and the transfer paper are peeled off. As a result, the ink is cut from the middle of the ink, and not the entire amount of the heated and melted ink but a part of the ink is transferred to the transfer receiving paper, and printing is performed many times.

The resin used in the present invention has a melting point (JIS-K0064)
Is a temperature range that can be heated by a normal thermal transfer printer head, i.e., 55 ° C to 110 ° C, and the melt viscosity at 120 ° C is 10,0.
Less than 00cps and freezing point from melting point (JIS-K0065)
Any resin can be used as long as it is 5 ° C. or lower. Examples of these resins include polyamide resins, polystyrene resins, polyethylene resins, polyether resins, polystyrene / acrylic copolymer resins, and phenol resins. The difference between melting point and freezing point is 5 ℃
Under the above conditions, these resins can be partially cross-linked by a cross-linking agent. The amount of these resins in the ink is preferably 20 to 80% by weight (based on solid content).

Further, the ink of the present invention is not limited to the above-mentioned resin alone, but may be used in combination with a general wax, a low-molecular substance, or a resin that does not fall into the above-mentioned category.

As the colorant used in the present invention, conventionally known various dyes or pigments such as yellow, red, blue and black can be used without any particular limitation. For example, as a black pigment, carbon black, oil black or the like is used.

It is more preferable that the ink of the present invention configured as described above also satisfies the condition that the freezing point is lower than the melting point (or softening point) by 5 ° C. or more.

The measurement of the melting point / solidification point of the ink is not suitable for the transparent melting point method and the like as performed for the resin. Therefore, the change in viscoelasticity with respect to the temperature change was evaluated to determine the melting point / solidification point. Here, as a simple method, evaluation was performed using a rigid pendulum type viscoelasticity meter DDV-OPA manufactured by Orientec. 1 ℃ ～ 5 ℃ / m
The cycle at the time of heating / cooling at the rate of in or the maximum change point of the DELTA value was defined as the melting point or the freezing point.

The ink of the present invention is used as a hot melt ink or a solvent ink at the time of coating on a support. However, it is more preferable to use it as a solvent ink in view of the viscosity adjustment of the ink, the thickness accuracy of the coating film, and the like. When preparing as a solvent ink, it is also possible to use a resin homogeneously dissolvable ink using a solvent that completely dissolves the resin to be used, or to combine at least a part of the resin with fine particles by combining with a solvent with low solubility of the resin to be used. The ink may be dispersed as the ink.

The support used in the thermal transfer recording ink film of the present invention is preferably a support having heat resistance, high dimensional stability and high surface smoothness. Specifically, a base film of a conventional thermal transfer recording ink film In addition to polyethylene terephthalate, which is mainly used for resin, polycarbonate, polyethylene, polystyrene, polypropylene, polyimide and other resin films with a thickness of 2-20
μ is preferably used.

〔The invention's effect〕

When a printing test was performed using a ribbon made of an ink film manufactured using an ink that satisfies the conditions described in the present invention, the optical density OD (measured by Macbeth) was measured up to the third time when black solid was printed five times using the same ribbon. ) Is 1.
In addition to the value of 0 or more, the fifth time showed a considerably high value of 0.8, and good performance as an ink was obtained many times.

〔Example〕

Hereinafter, the present invention will be described in more detail by examples,
The present invention is not limited to these examples.

Example 1 Melting point 90 ° C, freezing point 74 ° C (difference between melting point and freezing point 16 ° C), 12
An ink having the following composition was prepared using a polyethylene resin having a melt viscosity of 220 cps at 0 ° C.

Polyethylene resin 35% Polyethylene glycol 20% Ethylene / vinyl acetate resin 12% Carnauba wax 9% Dispersant 4% Carbon black 20% This ink is applied to a 6μ PET film so that the dry coating film becomes 8g / m ^2. , A commercially available thermal transfer printer (NE
Print evaluation was performed with C personal word processor Bungo Mini 7E). The evaluation was performed by continuous black solid printing. Using the same portion of the ribbon a plurality of times, the change in print density (measured by Macbeth) with respect to the number of prints was measured. The results are shown in FIG.

As is clear from Fig. 1, OD1.
It held 0 or more and showed high performance as an ink for multiple printings.

Example 2 Melting point 75 ° C, freezing point 63 ° C (difference between melting point and freezing point 12 ° C), 12
Α-olefin / maleic anhydride resin having a melt viscosity of 980 cps at 0 ° C. and a polyethylene resin having a melting point of 70 ° C., a freezing point of 64 ° C. (difference between the melting point and the freezing point of 6 ° C.) and a melt viscosity of 350 cps at 120 ° C. in a weight ratio of 1: 1 Using the ink, the following composition was prepared, and the same printing evaluation as in Example 1 was performed.

The results are shown in FIG. 1. As a result, the OD was kept at 1.0 or more until the third printing, and the ink exhibited high performance as a large number of printings.

α-olefin / maleic anhydride resin 30% polyethylene resin 30% ethylene / vinyl acetate resin 15% dispersant 5% carbon black 20% Comparative Example 1 Wax HNP-10 (melting point 75) manufactured by Nippon Seiro Co., Ltd. instead of polyethylene resin C. and a freezing point of 75 ° C.), and the other components were prepared with the same composition as in Example 1 and subjected to the same printing evaluation.

The results are shown in FIG. 1, but almost all of the ink was transferred in the first printing, and repeated use was not possible at all.

Example 3 Melting point 80 ° C, freezing point 74 ° C (difference between melting point and freezing point 6 ° C), 12
A polypropylene resin having a melt viscosity of 970 cps at 0 ° C.,
Melting point 63 ° C, freezing point 54 ° C (difference between melting point and freezing point 9 ° C), 120
Using polyethylene glycol having a melt viscosity at 45 ° C. of 45 cps, an ink having the following composition was prepared, and the same printing evaluation as in Example 1 was performed. The results are shown in FIG.

As is clear from FIG. 2, printing with relatively low printing density but extremely stable printing density was obtained.

Polypropylene resin 50% Polyethylene glycol 10% Ethylene / vinyl acetate resin 15% Dispersant 5% Carbon black 20%

[Brief description of the drawings]

FIG. 1 is a graph showing the change in the optical density of printing with respect to the number of printings of the ink ribbon obtained in Examples 1 and 2 and Comparative Example 1. FIG. 2 is a graph showing the printing with respect to the number of printings of the ink ribbon obtained in Example 3. 5 is a graph showing a change in optical density.

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Masanori Minato 1334 Minato, Wakayama-shi, Wakayama Kao Co., Ltd. Information Science Laboratories (56) References JP-A-61-169287 (JP, A) JP-A-61-179790 (JP, A) JP-A-61-169286 (JP, A) JP-A-57-105395 (JP, A) JP-A-62-13383 (JP, A) JP-A-61-83096 (JP, A) 1979-563044 (JP, A)

Claims (2)

(57) [Claims] (1) a melting point (JIS-K0064) of 55 ° C to 110 ° C,
A multi-use thermal transfer ink comprising a resin having a melt viscosity at 10,000 ° C. of not more than 10,000 cps and a solidifying point (JIS-K0065) lower than the melting point of at least 5 ° C., and a coloring agent as essential components. 2. The melting point (JIS-K0064) is 55 ° C to 110 ° C,
A resin having a melt viscosity at 10,000 ° C. of 10,000 cps or less and a solidifying point (JIS-K0065) lower than the melting point of 5 ° C. or more, and a thermal transfer ink containing a colorant as an essential component is applied to one surface of a support. A multi-use thermal transfer ink film characterized in that: