JPS59199295A - Ink composition for ink ribbon used for sublimation transfer type copying - Google Patents

Abstract

PURPOSE:To produce a transferred image having a hue extremely close to that of an original and prevent a fusion phenomenon from occurring between an ink ribbon and a copying paper, by constituting a binder of a resin having a glass transition point of higher than the sublimation starting temperature of a dye and a resin poorly compatible with the above resin and having a glass transition point of lower than the sublimation starting temperature of the dye. CONSTITUTION:The binder is constituted of a resin having a glass transition point of higher than the sublimation starting temperature of a dye and a resin poorly compatible with the above resin and having a glass transition point of lower than the sublimation starting temperature of the dye. An example of the resin having a glass transition point of higher than the sublimation starting temperature (namely, 120 deg.C) of the sublimable dye (the resin in hereinafter referred to as resin A) is cellulose acetate or ethyl cellulose. An example of the resin poorly compatible with resin A and having a glass transition point of lower than the sublimation starting temperature of the dye (this resin is hereinafter referred to as resin B) is polystyrene (PS) or polymethyl methacrylate (PMMA). It is preferable to use resin B in a quantity of 5-30wt% of the total weight of the binder resins.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ink composition for an ink ribbon for sublimation transfer type copying, and in particular to an ink composition suitable for forming a transferred image with a tone extremely close to that of the original image. It is.

Sublimation transfer copying uses an ink ribbon with an ink layer made of an ink composition mainly consisting of a sublimable dye and a binder on a heat-resistant substrate such as paper, and this ink ribbon is applied from the back side with a thermal head. A method of copying in which color images are formed by heating and thermally transferring dye onto photographic paper that is placed in contact with an ink layer.

In such a copying method, in order to obtain a transferred image with a tone extremely close to that of the original, it is necessary that the sublimable dye used in the ink composition has a good tone and that each dye has well-balanced thermal transferability. It is required to have a wide color reproduction range and good brown color reproducibility, and it is also required that no fusion phenomenon due to heat occurs between the ink ribbon and the photographic paper.

As the sublimable dye contained in the ink composition, disperse dyes are mainly used.

Among the commercially available disperse dyes corresponding to the respective complementary colors of the three primary colors blue-violet (B), green CG) and red (R), yellow (Y), magenta color CM) and cyan color CC),
Examples of dyes with good color tone and good thermal transferability include dye coatings such as Color Index (CEolour In
dex, 5ociety of Dyer
s & Colourists (English) and Ameri
can As5 association of Textil
e Chemists & Co1orists (US)
Co-edited by C.1, hereinafter referred to as C.1), 11 listed under the names of C.I.
A total of 12 types can be listed, including one type of disperse dye and one type of other disperse dye (product of Sumitomo Chemical Co., Ltd.). These dyes are as follows.

Y: Disperse Yellow 8,86.
122, 7.104 and Disperse Orange
e 55 (6 types in total): M 2 Disperse R
ed 15 and 5olvent Red 15
5 (2 types in total); and C: TS-618 (trade name of Sumitomo Chemical product), D
isperseBlue 198, 60 and 118 (
Total of 4 types].

For evaluation of the thermal transferability of these disperse dyes, an ink ribbon is prepared by applying an ink consisting of 300 parts by weight of Lycagel fine particles onto the surface of rice paper so that the coating thickness after drying and calendering is 2 μm. . A transparent polyester film is placed over the ink layer of this ribbon, and the ink ribbon is transferred by heating with an iron set at a constant temperature from the back side, and the color density of the dye transferred to the film is measured using a Macbeth reflection densitometer.

Each of the 12 types of disperse dyes! Regarding color, the following dyes in particular have the best hue and the best thermal transferability as measured by the evaluation method described above.

Y: Disperse Yellow□ 3 (Hereafter, Y, 3 (!: say); M: Disperse
e Red 15 (hereinafter referred to as R, 15); and C: TS-61B Ink ribbons were prepared in the same manner as above using these six types of disperse dyes, and a thermal transfer property test was conducted.Iron temperature The relationship between the heating time and the color density of each dye was as shown in Table 1.

Table 81 The results show that TS-618, which has a cyan color tone, has extremely low thermal transferability compared to the other two dyes. In addition, in this test, each dye was
It was found that it exhibits sublimation property.

Therefore, it is generally necessary that the Tg of the binder of the ink composition be higher than 120C to avoid fusion phenomena between the ink ribbon and the photographic paper.

Conventionally, sublimable dyes having a cyan tone, for example, used in ink compositions for ink ribbons are selected from the viewpoint of transfer efficiency, sublimation amount, and coloring density, and dyes with good dyeing properties are selected.
The color tone was sacrificed.

Therefore, conventional ink compositions have insufficient color reproducibility, making it difficult to obtain close-up images with satisfactory color tones.

In view of these problems, the inventors of the present invention have conducted intensive research to form a transferred image that has excellent balance in thermal transferability, has a tone extremely close to that of the original image, and that is fused with photographic paper during thermal transfer. It was possible to obtain an ink composition for an ink ribbon for sublimation transfer type copying that does not cause a sticking phenomenon. That is, the present invention provides an ink composition for an ink ribbon for sublimation transfer copying which mainly contains a sublimable dye and a binder, wherein the binder is a resin having a glass transition point higher than the sublimation start temperature of the sublimable dye. and a resin having poor compatibility with the resin and having a glass transition point lower than the sublimation initiation temperature.

In the binder contained in the ink composition of the present invention, a resin having a glass transition point higher than the sublimation start temperature (i.e. 12011:') of the sublimable dye (hereinafter referred to as "Kizuki A") is cellulose acetate, Examples include ethyl cellulose, cellulose acetate-1-phthyl-1-, cellulose propionate, melamine, polycarbonate, phenol resin, etc.Also, they have poor compatibility with the resin and have a glass transition point lower than the sublimation temperature. Examples of the resin (hereinafter referred to as resin B) include polystyrene (hereinafter referred to as P8), polymethyl methacrylate (hereinafter referred to as P8), and polymethyl methacrylate (hereinafter referred to as P8).
MMA), other acrylic resins (e.g. polybutyl methacrylate, polymethyl acrylate), linear polyurethane, polyethylene, polypropylene, polyvinyl acetate, polyamide, polyvinyl chloride, vinyl chloride/vinyl acetate/P
Examples include VA copolymers and epoxy resins. Resin B
can be used in a proportion of 5 to 30% by weight in the total binder resin; less than 5% by weight will not show any effect;
If the amount is more than 0% by weight, a fusion phenomenon tends to occur between the ink ribbon and the photographic paper, which is not preferable.

In the ink composition of the present invention, the sublimable dye can be used in an amount of 10 to 1000 parts by weight based on 100 parts by weight of the total binder resin; if it is less than 10 parts by weight, the color density will be too low; , even if the amount is more than 100 parts by weight, no particularly significant effect is observed, which is disadvantageous in terms of cost.

The glass transition point and compatibility of the resins A and B are measured using an automatic viscoelasticity measuring device (manufactured by Toshisha Co., Ltd., hereinafter referred to as TEA device). That is, by changing the ratio of resins A and B, Make a solution with a concentration of about 10% by weight by dissolving it in a suitable solvent.
), and measured the temperature dependence of dynamic loss rate (G), and from the graph obtained, the temperature corresponding to the thickest value of G was determined as the glass transition point. Regarding compatibility, in the above graph, if G" shows two extreme values, these resins have poor compatibility, and the two temperatures corresponding to these two maximum values are the glass transition of each resin. When the two resins are compatible, there is only one extreme value in the graph showing the temperature dependence of G'', and the temperature corresponding to this, that is, the crow transition point of the resin mixture, is the crow transition point of the ordinary resin. It will be located in the middle of the transition point.

Examples of the present invention will be discussed below. In the examples, disperse dye TS-618 is used as the sublimable dye. This is because the effect of the invention is more clearly demonstrated by using TS-618, which is a dye with the best cyan color tone, but is extremely difficult to sublimate compared to dyes with other colors. It is not meant that the sublimable dyes used in the present invention are limited thereto.

Examples 1 and 2 Using cellulose acetate as resin A, resins B and 1, TP
Ink was prepared by adding 540 parts by weight of methyl ethyl ketone to the composition shown in Table 12. In addition, as a comparative example, an ink containing no Ps was similarly prepared from the composition shown in Table 2.

All numbers represent parts by weight.

Part 2 ShishiUse each of these inks on rice paper.
Drying - Should the coating thickness be 2μ after calendering? An ink ribbon was created by coating this.

Photographic paper coated with polyester resin on the surface of the paper was layered on the ink layer of the ink ribbon, and the rate of increase in the amount of sublimation of the dye was determined from the rate of increase in pulse width of 2Q, ms applied from the ink ribbon side to the thermal head. . The line PS in Figure 1 shows the relationship between this rate of increase and the amount of PS added. Gender is tampered with. However, in this Example and Comparative Example 2, no fusion phenomenon occurred between the ink ribbon and the photographic paper.

In order to investigate the glass transition points of the binders used in this example, namely cellulose acetate and PS, and the compatibility between the two, the temperature dependence of the dynamic loss rate was measured using a Tr3A apparatus by changing the ratio fi of each resin. It was measured.

The measurement results are shown in graph form in Figure 2. The glass transition point of cellulose acetate (!:PS) is 214, respectively.
It can be seen that C and 105C have poor compatibility.

Examples 6 and 4 Ink ribbons were prepared in the same manner as in Examples 1 and 2 except that pM and MA were used instead of P and S, and the rate of increase in the amount of sublimation of the dye was determined based on the comparative example. I asked for it. As shown by lines P IM and MA in FIG. 1, as the amount of PMMA added increases, the amount of sublimation of dye TS-618 increases linearly, and the sublimability is improved. Further, in this Example and Comparative Example, no fusion phenomenon occurred between the ink ribbon and the photographic paper.

Note that for cellulose acetate and PMMA used in this example, the temperature dependence of the dynamic loss rate was measured in the same manner as in the previous example. The measurement results are shown in graph form in Figure 3. 6th
From the figure, it can be seen that the glass transition points of cellulose acetate and PMMA are 214C and 115C, respectively, indicating poor compatibility.

According to the present invention, for example, an ink ribbon can be created using the ink composition shown in Table 6. All numbers are by weight.

Table 6 When color originals are thermally transferred using these ink ribbons, compared to images obtained with conventional ink ribbons,
Images with a wide color reproduction range and improved brown color reproducibility can be obtained.

[Brief explanation of drawings]

Figure 1 shows P M M or Pst in the ink composition.
Graphs showing the relationship between the amount of addition and the rate of increase in the amount of dye sublimation, Figures 2 and 6 show the temperature dependence of the dynamic loss rate of binder resins consisting of cellulose acetate and PS and cellulose acetate and PMMA, respectively. This is a graph showing. Agent Masaru Ueya〃 Yoshio Tsunekako〃 Toshiki Sugiura-51・

Claims (1)

[Claims] In an ink composition for an ink ribbon for sublimation transfer type copying mainly consisting of a sublimable dye and a binder, the binder comprises a resin having a glass transition point higher than the sublimation start temperature of the sublimable dye, and the resin. An ink composition comprising a resin having poor compatibility and a glass transition point lower than the sublimation initiation temperature.