JPS6347639B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal recording medium such as an ink donor sheet used for transfer-type thermal recording in which a heat-sublimable or heat-melting ink layer is selectively heated and transferred and recorded onto a recording paper. In particular, it relates to a thermal recording medium that prevents missing or uneven recording due to end marks.

A cross-sectional view of a commonly used thermal recording medium is shown in FIG. 1, and a schematic diagram of a recording apparatus in which the medium is used is shown in FIG. In the figure, reference numeral 1 denotes a heat-melting ink layer, which is applied onto a base film 2 such as capacitor paper, and both form a thermal recording medium 3.

This thermal recording medium 3 usually has the same color on its entire surface, such as black or red, and is set in a rolled state in a recording device. Then, as shown in FIG. 2, it is selectively heated by a thermal head 4, and transferred and recorded onto a recording paper 5 by a counter roll 6.
The vehicle is driven in the direction of the arrow shown in the figure.

An end mark is provided on the thermal recording medium 3 so that it can be detected that the end of the medium is near. Usually, as this end mark, a substance that differs in at least one of the hue, density, and reflectance of the heat-fusible ink layer 1 is thinly applied at a predetermined distance from the end of the roll-shaped thermal recording medium 3. be done.

Further, when it is detected by the end mark that the end of the rolled thermal recording medium 3 is near, the control device (not shown) controls the transfer of the recording page in the middle of recording at least at that time. , operates to complete the record.

Therefore, even if an end mark is detected, the thermal recording medium 3 is designed to immediately stop running and recording will not be interrupted.

This end mark needs to be applied to the heat-melting ink layer 1 side. This is because if the end mark is provided on the base film 2 side, it will come into direct contact with the thermal head 4, which may cause the head to become dirty and reduce the recorded image quality, or cause it to be placed on the travel path of the thermal recording medium 3. This is because the end mark may easily come off due to being rubbed by a certain shaft (not shown).

For this reason, the end mark is painted on the heat-melting ink layer 1, but if the end mark overlaps with the recorded image, as described above,
Since the ink layer 1 and the end mark are different in at least one of hue, density, and reflectance, there is a drawback that omissions and unevenness occur in recording in that portion.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal recording medium that eliminates the above-mentioned drawbacks and prevents missing or uneven recording due to end marks.

In order to achieve the above object, the present invention provides an end mark provided on a heat-fusible ink layer that differs from the heat-fusible ink layer in at least one of hue, density, and reflectance at room temperature. It is characterized in that it has optical or physical properties that change to approximately the same hue, density, or reflectance when heated to a certain temperature.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 3 is a sectional view of one embodiment of the present invention, and FIG. 4 is a partially sectional perspective view thereof. In the figure, 11 is a heat-melting ink layer, 12 is a base film on which the heat-melting ink layer 11 is applied, and 13 is a heat-melting ink layer.
is the heat-melting ink layer 11 and the base film 1
A thermal recording medium 14 formed by 2 and 14 is spaced a predetermined distance from the end of the thermal recording medium 13,
This is an end mark provided on a portion of the upper surface of the heat-melting ink layer 11.

An example of the composition of the heat-melting ink layer 11 used by the present inventors is shown in Table 1. This heat-melting ink layer 11 exhibits a black color.

Note that if the purity of the carnauba wax or ester wax shown in Table 1 is lowered or the ratio of carbon black is increased, the ink layer 11
Since the melting point temperature of the material increases, the recording density decreases at the same heating temperature.

Table 1 Pigment (carbon black) 20% (weight%) Carnauba wax 20% Ester wax 40% Oil (castor oil, etc.) 10% Other additives (EVA, etc.) 10% Melting point Approximately 60℃ The inventors In the experiment, ink layer 11 in Table 1
3 on the top surface of the capacitor paper base film 12.
Thermal recording medium 13 was prepared by coating to a thickness of ~12 μm.

Further, the end mark 14 has a characteristic that it is white at room temperature, melts when heated to a certain temperature, and at the same time changes color to black and transfers together with the heat-fusible ink layer 11.

Table 2 shows an example of the composition of an end mark having the above characteristics.

Table 2 Carnauba wax 10-20% (weight%) Ester wax 20-40% Oil 10% Leuco dye 1-5% Bisphenol A 1-10% Polyvinyl alcohol 10-20% Calcium carbonate (or oxidized Titanium)
5-30% Other additives 10% Melting point 50-60% The heat-melting ink layer 11 and end mark 14
Due to the difference in melting point of the end mark 14, the ink layer 11
In the part painted on top, the end mark 14 is
At a heating temperature lower than that of the ink layer 11 (50 to 60° C.), the color changes from white to black.

Therefore, even if the heat-melting ink layer 11 in that part melts and transfers together with the end mark 14, it will be mixed with the end mark 14 which has already turned black, which will prevent recording omissions and No unevenness occurs.

In the above case, the hue of the heat-fusible ink layer 11 and the end mark 14 after melting is not limited to black, and even hues such as red or colorless may have the above-mentioned characteristics. Of course it's a good thing to have.

Further, the hue of the end mark 14 at room temperature does not have to be white;
Any material that can be distinguished from No. 1 in at least one of hue, density, and reflectance is sufficient.

As described above, the present invention provides an end mark provided on a thermofusible ink layer that differs from the thermofusible ink layer in at least one of hue, density, and reflectance at room temperature, and This material has optical or physical properties that change when heated to approximately the same hue, density, and reflectance, thereby preventing missing or uneven recording due to end marks. There is an advantage.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a thermal recording medium, FIG. 2 is a schematic diagram of a recording device, FIG. 3 is a sectional view of an embodiment of the present invention, and FIG. 4 is a partially sectional perspective view thereof. 1, 11... Hot melt ink layer, 2, 12...
Base film, 3, 13...Thermal recording medium, 14
...End mark.

Claims (1)

[Claims] 1. In a thermal recording medium having a base film and a thermofusible ink layer coated on the upper surface of the base film, one of the thermofusible ink layers is placed at a predetermined distance from the end of the thermal recording medium. At room temperature, at least one of hue, density, and reflectance is different from that of the heat-melting ink layer, but when heated to a certain temperature, the color changes and the hue is approximately equal to that of the heat-melting ink layer. A thermal recording medium comprising an end mark having optical or physical properties such as , density or reflectance.