JPH01281992A - Ink for thermal fusion transfer type full-color printer - Google Patents

Abstract

PURPOSE:To prevent missing of dots from occurring, by setting the melt viscosities of at least three primary color inks, i.e., yellow, magenta and cyan inks of ink films to be gradually lowered in the order of transferring, by regulating the amount of a thermoplastic resin such as EVA and EEA contained in each of the inks. CONSTITUTION:Ink films 12-14 for a thermal fusion transfer type full-color printer are produced by setting the melt viscosities of at least three primary color inks for yellow (Y), magenta (M) and cyan (C) to be gradually lowered in the order of transferring, by regulating the amount of a thermoplastic resin such as EVA and EEA contained in each of the inks. For example, the Y ink of the Y film 12 is transferred with a full density on a transfer recording paper 11, then the M ink of the M film 13 is transferred with a full density thereon, and the C ink of the C film 14 is transferred thereon by linearly increasing the duration of pulses applied by a thermal head, whereby 16-gradation transferring can be achieved. Thus, missing of dots is prevented from occurring at the time of releasing the ink film, and a clear image can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ink for use in a thermal melt transfer type full-color printer.

[Conventional technology] In recent years, thermal transfer recording has become non-impact, noiseless, low-cost,
It has become popular due to its features such as being able to be miniaturized, and in particular, as a full-color recording capable of expressing gradation, thermal melt transfer recording is compatible with plain paper, has high printing speed, and has low power consumption, making it a promising hardware for the future. It is attracting the most attention as a copying device.

Various types of thermal melt transfer type full-color blinking inks have been reported, but their required characteristics include solid state during printing.
A clear phase change from liquid to solid must occur in a short period of time. Therefore, the main components of these inks were natural waxes or synthetic waxes containing hydrocarbons as a main component, to which coloring agents such as pigments and dyes were added.

In addition, the following three elements are particularly important as the performance of thermal melt transfer type full color blinking ink: ink coverage during ink overlay, gradation from low density to high density, and dot reproducibility. In order to improve the dispersibility of the ink colorant and the dot reproducibility, it is effective to use polar wax as the main component and increase the resin content. Furthermore, in order to improve the gradation properties, it has been effective to use paraffin wax, etc., which has a low melt viscosity and low hardness when solid, as the main component, and to reduce the resin content.

[Problems and objects to be solved by the invention] However, with the above-mentioned conventional technology, it is difficult to achieve both ink coverage and gradation, and ink with good coverage has poor gradation and becomes binary, and also has poor gradation. Good ink does not adhere well to the second and third colors, resulting in images with poor color reproducibility.

Furthermore, the transfer conditions vary greatly depending on the order in which the yellow, magenta, and cyan color inks are transferred.

For example, the first color is transferred onto the transfer paper, so a great adhesive force such as an anchoring effect can be expected, but the second and third colors are transferred onto the transfer paper and the ink, so the adhesive strength can vary. In particular, when the ink film of the third color is peeled off after transfer, the transferred dots are carried away by the ink film again, causing dot omission, which significantly deteriorates the quality of printing or printing.

``Means to Solve the Problem 1 The ink for full-color melt transfer printers of the present invention is
The present invention is characterized in that the melt viscosity of at least the three primary color inks of yellow, magenta, and cyan is decreased in accordance with the transfer order. Furthermore, as a means for this, EVA,
Alternatively, the above object is achieved by changing the content of thermoplastic resin such as EEA.

[Function] According to the above structure of the present invention, even if the first color ink has a high melt viscosity, the anchoring effect due to the paper surface etc. on the transfer paper is not (
U]<, a large adhesive force can be obtained. Also the second color, 3
As the color of the ink increases, the content of thermoplastic resin decreases, so the adhesive strength, cohesive force, and flexibility of the ink decrease. Therefore, the adhesive force between the ink film and the support layer decreases in accordance with the order of transfer, so that the overlapping of the inks progresses smoothly, and it is possible to prevent dots from falling out when the ink film is peeled off. Furthermore, as the cohesive force of the ink gradually decreases, the shape of the transferred dots becomes dependent on the pressure of the pad, making the dots look blurry, which is also effective in reducing the roughness of the printed surface.

EXAMPLES Hereinafter, the effects of the present invention will be specifically explained with reference to Examples.

[Example] All ink compositions shown in the following Examples and Comparative Examples are in weight %.

Example 1 Yellow ink composition Colorant Fast Yellow LOG 10% Carnauba wax No. 1 13% [Daily Fine Products (...1) Paraffin wax 130F 35% [Nippon Seisuke ■1 Oxidized wax N5P6010 30% [Japan Seisuke ■] Resin Evaflex EV410 12% [Mitsui DuPont Chemical ■1 Magenta ink composition Colorant Carmine 6B 10% Carnauba wax No. 1 15% Paraffin wax 1
30F 35% oxidized wax N5P6010
30% resin EV4] 0 10
% Cyan ink composition Colorant Fuclocyanine blue 10% Carnauba wax No. 1 20% Paraffin wax 1
30F 35% oxidized wax N5P6010
30% resin EV410 5
A mixture of each color ink with a top composition of The roll is water-cooled and passed through 15 times) P'l in three colors: cyan, magenta, and yellow! l
A melt-transfer type full-color blinking ink was created.

Example 2 Yellow ink yarn coloring agent Fast Yellow 1.0g 10% Carnauba wax No. 1 13% Paraffin wax 1.30 F 35% Oxidized wax N5P6
010 30% resin DPDJ-91.69
12% [Nippon Unicar ((1→) Mazenk Ink Composition Colorant Carmine 6B 10% Carnauba Wax No. 1 15% Paraffin Wax 1
30F 35% oxidized wax N5P6010
30% resin DPDI-9169 1.
0% cyan ink composition Colorant Phthalocyanine blue 10% Carnauba wax No. 1 20% Paraffin wax 1
．． 30 F 35% oxidized wax N S P
60 ], 0 30% resin DPDI-9169
5% A mixture having the above composition was subjected to a dispersion treatment in the same manner as in Example] to prepare an ink.

Example 3 Yellow ink composition Colorant Fast Yellow], OG 10% carnauba wax No. 1 13% paraffin wax 1.30 F 35% oxidized wax N5P6
010 30% Resin MB-08012% (Nippon Unicar ((1→) Magenta ink composition Colorant Carmine 6B 10% Carnauba wax No. 1 15% Paraffin wax 1
30F 35% oxidized wax N5P6010
'30% resin MB 080
10% cyan ink composition Phthalocyanine blue 10% Carnauba wax No. 1 20% Paraffin wax 1
．． 30 F 35% oxidized wax N5P60]
0 30% Resin MB-0805% A mixture having the above composition was dispersed in the same manner as in Example 1 to prepare an ink.

Comparative Example 1 Ink composition Colorant Same as Example 1 10% each Carnauba wax No. 1 20% paraffin wax 130F 55% oxidized wax-NS
A mixture of P6010 10% EVA-MBO 805% Upper Era composition was dispersed in the same manner as in Example 1 to prepare an ink.

Comparative Example 2 Ink composition Colorant Same as Example 1 10% each Carnauba wax No. 1 20% paraffin wax 130F 1.0% oxidized wax
NSP60], 055% EVA-MBO805% The above mixture was dispersed in the same manner as in Example] to prepare an ink.

Table 1 also shows the melt viscosity of each ink obtained in Examples 1 to 63 and Comparative Example 1.2.

The melt viscosities listed in Table 1 are the values measured at 110° C. using a B-type viscometer (using No. 1 Roku) manufactured by Tokyo Keiki ■.

Table 1 Also, each ink obtained from the above Example 1.2.3 and Comparative Example 1.2 was melted by heating at 10°C to a thickness of 6 μm.
A hot-melt coating was applied to a PET film of 500 mm using a wire bar to prepare an ink for a hot-melt transfer type full-color printer with an ink layer thickness of approximately 4 μm.

An ink overlay test was conducted using this ink film. In the ink overlay test, as shown in FIGS. 1 and 2, first, yellow ink was transferred at full density onto transfer paper 11, and then magenta ink 13 was transferred onto yellow ink 12 at the same full density. Furthermore, cyan ink 14 was transferred onto the yellow ink+magenta ink.

At this time, the resolution is 180 dpi, and the resistance value of 1 heating element is 200.
Using a thermal head of Ω, the amount of heat applied (L6mj/dot
, Full density transfer of yellow ink and magenta ink with an applied pulse width of 0.48 m5ec, cyan ink is 0.48 m5ec
The pulse width was linearly increased in m5ec/1.6 steps to achieve 16 gradation transfer.

Separately, three colors, yellow ink 21, magenta ink 22, and cyan ink 23, were transferred in six gradations. The evaluation is based on the optical density (OD) value of cyan ink on yellow ink + mazenk ink on the transfer paper of each gradation, and the optical density (OD) value of cyan ink on yellow ink + mazenk ink +
Compare the optical density values of each positive tone of cyan ink, and add 1 to the dot.
A c b et hTR-927 type was used. The OD values in FIGS. 3 to 9 are normalized to 0 in order to accurately compare each measurement data. In addition, the transfer paper 11
Mitsubishi Paper Industries (TTR manufactured by Wolf was used.

3 to 9 show the results of ink overlay tests for Examples 1 to 3 and Comparative Examples 1 and 2. By comparing the density of cyan ink on the transfer paper with the density of cyan ink on yellow ink + magenta ink, you can check the adhesion of the third color ink, and further compare the density of yellow ink + magenta ink + cyan ink to determine the adhesion of the third color ink. You can tell how well the ink transfers. Also, by comparing the slopes of the curves, it is possible to know whether the gradation is good or bad. The dot shape was evaluated by visually observing the printed sample.

Comparative Example 1 Ink rich in paraffin wax (Figures 6 and 9) has good gradation, but the density of the cyan ink on the magenta ink is low and the ink rideability is poor. Recognize. In addition, as in Comparative Example 2 (Figures 7 and 9), ink rich in oxidized wax has a high concentration of cyan ink on magenta ink and has good ink rideability, but has poor gradation. Midtones are no longer reproduced. In addition, variations in density within the density range, such as missing dots and dot connections, or a rough feeling on the printed surface are observed. However, as shown in the examples, if the ink melt viscosity is reduced according to the order in which the inks are superimposed, it is possible to achieve both ink coverage and gradation without significantly changing the ink composition for each color.

Furthermore, Table 2 shows the evaluation results regarding the reproducibility of the transferred dots.

The symbols in Table 2 have the following meanings: ○ No dot holes were observed, indicating good dot reproducibility.

△・Dots are slightly removed.

×・Dra】・Reproducibility is extremely poor.

In this way, the ink for thermal melt transfer printers of the present invention can also control the dot shape, making it possible to obtain high quality prints.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide an ink for heat-melting transfer type prinks that is excellent in both ink coverage and gradation.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are explanatory diagrams of an ink overlay test. 3 to 9 are diagrams showing the results of ink overlay tests in terms of OD values of transfer inks. Applicant Seiko Epson Co., Ltd. Agent Patent Attorney Kisanbe Meiki (and others) OD (1,0
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Claims (2)

[Claims] (1) At least 3 each of yellow, magenta, and cyan
An ink for a thermal melt transfer type full-color printer, characterized in that the melt viscosity of the primary color ink is reduced in accordance with the transfer order. (2) The thermal melt according to item 1, wherein the melt viscosity is adjusted by changing the content of thermoplastic resin such as EVA or EEA in the composition of the three primary color inks of yellow, magenta, and cyan. Ink for transfer type full color printers.