JPH11157217A - Thermal transfer recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high definition image in a thermosensitive transfer recording medium using a thin film resin ink layer. SOLUTION: This thermosensitive transfer recording material has a thermosensitive transfer ink layer, on one of the faces of a base material which is composed of 25-60 wt.% of pigment, 20-75 wt.% of waxes with a melt point falling within the range of 6-110 deg.C and 0-15 wt.% of thermoplastic resin and is 0.2-1.0 μm thick. The waxes are such that contains one kind or two or more kinds selected from the group of an α- olefin/maleic anhydride copolymer, max, oxidized wax, candililla wax, carnauba wax, montan wax and synthetic ester wax.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer printing system in which a thermal transfer ink layer containing a pigment is selectively thermally transferred onto an image receiving body to form a high-density and high-definition image, particularly a color image. The present invention relates to a thermal transfer recording medium to be formed.

[0002]

2. Description of the Related Art A thermal transfer recording medium of this type has a basic structure in which a thermal transfer ink layer containing a pigment is provided on one surface of a base material. In many cases, the thickness is about 2 to 5 μm, so that it was difficult to obtain a high-definition image.

In this regard, Japanese Patent Application Laid-Open No. HEI 7-117359 proposes a technique for obtaining a high-definition image by reducing the thickness of an ink layer. The ratio of the contained resin component was high, and therefore, the ink layer was difficult to cut, the obtained image lacked sharpness of the edge, and a high-definition image could not be obtained.

[0004]

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned disadvantages of the prior art and provides a thermal transfer recording medium capable of forming a high-density and high-definition image, particularly a color image, using a thin ink layer. That is the task.

[0005]

According to the present invention, there is provided (1) a heat-sensitive transfer ink layer on one side of a substrate, wherein the heat-sensitive transfer ink layer has a pigment content of 25 to 60% by weight and a melting point of 60 to 110 ° C. A thermal transfer recording medium comprising 20 to 75% by weight of waxes and 0 to 15% by weight of a thermoplastic resin and having a film thickness in the range of 0.2 to 1.0 μm.

Further, the present invention provides (2) the above-mentioned (1), wherein the pigment is dispersed in the ink layer in a state where 70% or more of the pigment particles have a particle size of 1.0 μm or less. The present invention relates to the thermal transfer recording medium described above.

Further, the present invention is characterized in that (3) the color of the thermal transfer ink layer is yellow, magenta or cyan, and the transmittance of the ink layer of each color is 62% or more. ) Or (2).

The present invention further provides (4) the waxes selected from the group consisting of α-olefin / maleic anhydride copolymer waxes, oxidized waxes, candelilla waxes, carnauba waxes, montan waxes and synthetic ester waxes. The present invention relates to the heat-sensitive transfer recording medium according to the above (1), (2) or (3), which comprises one or more kinds.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The thermal transfer ink layer of the present invention comprises 25 to 60% by weight of a pigment, 20 to 75% by weight of a wax having a melting point in the range of 60 to 110 ° C., and 0 to 15% by weight of a thermoplastic resin. Consisting of 0.2 to 1.0 μm
m of the ink layer.

In the present invention, the disadvantage that the sharpness of the ink layer in the conventional example is inferior is solved by using the thin-film type ink layer and increasing the content of waxes in the vehicle. It has become possible to obtain high-definition images.

If the content of the wax is lower than the above range, the thermal transfer sensitivity and the sharpness of the ink layer become poor, and a high-definition image cannot be obtained. On the other hand, if it is higher than the above range, the content of the pigment is relatively reduced, and the printing density cannot be secured. From these points, the content of the wax in the ink layer is more preferably 35 to 70% by weight.

The thermoplastic resin is preferably blended from the viewpoint of preventing the ink layer from falling off the base material and securing the adhesive force to the image receiving member. Images are difficult to obtain. From this point, it is preferable that the amount be 15% by weight or less of the ink layer, especially 2 to 10% by weight.

The content of the pigment is preferably 25 to 60% by weight, more preferably 30 to 60% by weight, from the viewpoint of securing the printing density.
５０50% by weight. If the content of the pigment is lower than the above range, a sufficient image density cannot be obtained, while if the content is higher than the above range, the fluidity of the ink decreases and it becomes difficult to form a uniform ink layer.

The thickness of the ink layer is preferably in the range of 0.2 to 1.0 μm. If the thickness of the ink layer is larger than the above range, a high-definition image cannot be obtained. I can't secure it.

[0015] Among the ink layers in the present invention, the ink layer used to express colors by extinction color mixture is a substantially transparent ink layer, and preferably, the transmittance of the ink layer of each hue is 62% or more. . Here, the transmittance of the ink layer is
The average transmittance in the wavelength range (non-absorption band of the ink layer of each hue) shown in Table 1 for the ink layer of each hue.

[0016]

[Table 1]

If the ink layer of each hue is not substantially transparent, especially if the transmittance of the ink layer of each hue is lower than 62%, a dull image is obtained when a multi-color or full-color image is obtained by subtractive color mixing. This tendency is particularly noticeable when an image is formed on an OHP (overhead projector) sheet.

In the ink layer of the present invention, the pigment is
Preferably, 70% or more of the pigment particles are dispersed in a state of a particle size of 1.0 μm or less. Since the pigment is finely dispersed in the ink layer, the transparency of the ink layer can be achieved, and the color reproducibility of a color image can be improved.

In the present invention, when forming a multi-color or full-color image including a region in which a color is developed by subtractive color mixture by superposing ink dots of different hues, the hue is usually yellow, magenta, or magenta. A cyan ink layer is used. If necessary, a black ink layer may be used.

As the pigment used in the ink layers of the yellow, magenta and cyan hues, a transparent pigment is preferably used. Here, a transparent pigment refers to a pigment that can give a substantially transparent ink when dispersed in a transparent vehicle. Examples of such a transparent pigment include the following.

Examples of the yellow transparent pigment include naphthol yellow S, Hanza yellow 5G, Hanza yellow 3G, Hanza yellow G, Hanza yellow GR,
Hanza Yellow A, Hanza Yellow RN, Hanza Yellow R, Benzidine Yellow, Benzidine Yellow G, Benzidine Yellow GR, Permanent Yellow NCG,
One or two organic pigments such as quinoline yellow lake
More than species can be used.

Examples of the magenta transparent pigment include permanent red 4R, brilliant fast scarlet, brilliant carmine BS, permanent carmine FB, lithol red, and permanent red F5.
One or more organic pigments such as R, brilliant carmine 6B, pigment scarlet 3B, rhodamine lake B, rhodamine lake Y, and alizarin lake can be used.

As the cyan transparent pigment, for example, one or more organic pigments such as Victoria Blue Lake, Phthalocyanine Blue, metal-free Phthalocyanine Blue, and Fast Sky Blue can be used.

Since the black ink layer does not usually overlap the ink layers of other hues, the pigment used for the ink layer need not be transparent. For example, pigments such as carbon black and aniline black can be used.

As the waxes used in the ink layer, generally used waxes can be used without particular limitation as long as the melting points fall within the range of 60 to 110 ° C. The reason why the melting point of the wax is set to 60 to 110 ° C. is to secure transfer sensitivity and storage stability.

Examples of the waxes include natural waxes such as lanolin, carnauba wax, candelilla wax, montan wax, and ceresin wax; petroleum waxes such as paraffin wax and microcrystalline wax; oxidized wax, synthetic ester wax, and polyethylene wax And synthetic waxes such as α-olefin / maleic anhydride copolymer wax, urethanized wax, Fischer-Tropsch wax and synthetic petroleum wax. These waxes may be used alone or in combination of two or more.

From the viewpoint of obtaining a transparent ink by finely dispersing the pigment as described above, it is preferable to use waxes having good dispersibility of the pigment. Examples of such waxes include α-olefin / maleic anhydride copolymer wax, oxidized wax, candelilla wax, carnauba wax, montan wax, and synthetic ester wax. Such waxes are preferably contained in an amount of at least 10% by weight, especially at least 25% by weight of the total waxes.

As the thermoplastic resin (including elastomer) used as necessary, for example, ethylene /
Vinyl acetate copolymer, ethylene / vinyl butyrate copolymer,
Ethylene / (meth) acrylic acid alkyl ester copolymer, (meth) acrylic ester resin, vinyl chloride resin, vinyl chloride / vinyl acetate copolymer, polyester resin, polyamide resin, epoxy resin, cellulose resin Natural rubber, styrene / butadiene copolymer, isoprene polymer, chloroprene polymer, petroleum resin, rosin resin, terpene resin, cumarone-indene resin and the like. These resins may be used alone,
Two or more kinds may be used in combination.

In addition to the above components, a dispersant, an antistatic agent, a plasticizer, and the like can be appropriately added to the ink layer as needed.

The ink layer in the present invention can be formed by mixing the above-mentioned components at a predetermined ratio and hot-melt coating an ink obtained by sufficiently kneading with a disperser in a molten state on a substrate. Further, it can also be formed by solvent coating.

In the heat-sensitive transfer recording medium of the present invention, the yellow, magenta, and cyan ink layers and, if necessary, the black ink layer may be provided on different base materials, respectively, or they may be formed on a single substrate. It may be provided on a substrate.

In one embodiment of the thermal transfer recording medium in which the ink layers of each color are arranged side by side on a single substrate, a yellow ink layer, a magenta ink layer,
The cyan ink layer and, if necessary, the black ink layer are arranged side by side in a certain order as one repeating unit. The order of arranging these three or four color ink layers in the repeating unit may be appropriately determined in consideration of the overlapping order of the respective colors.

As the substrate, a polyethylene terephthalate film, a polyethylene naphthalate film,
Polyester film such as polyarylate film,
A polycarbonate film, a polyamide film, an aramid film, and various other plastic films generally used as a substrate film for this type of ink ribbon can be used. Also, high-density thin paper such as condenser paper may be used. Various heat-resistant resins such as silicone-modified urethane resin and silicone-modified acrylic resin modified with silicone resin, fluororesin, nitrocellulose resin, or the like on the back surface of the base material (the surface that is in sliding contact with the thermal head); Alternatively, a conventionally known stick preventing layer made of a mixture of a heat-resistant resin and a lubricant may be provided. The thickness of the base material is 1.5 to increase transfer sensitivity and reduce heat diffusion to obtain a high-definition image.
The range is preferably from 5 to 5 μm.

To form a color image on an image receiving body using the thermal transfer recording medium of the present invention, for example, a separated color signal of a color image, that is, a yellow signal by a thermal printer,
In accordance with the magenta signal and the cyan signal, the yellow ink layer, the magenta ink layer, and the cyan ink layer are selectively and thermally transferred one by one to form a yellow separated image, a magenta separated image, and a cyan separated image on a receiver. The transfer order of the yellow ink layer, the magenta ink layer, and the cyan ink layer can be arbitrarily selected. In the case of a normal color image, all three color ink layers are selectively transferred in accordance with the three color signals to form a separated image of three colors of yellow, magenta, and cyan, but there are only two color signals. In such a case, the corresponding two-color ink layers are selectively transferred to form separated images of two colors of yellow, magenta, and cyan. Thus, a color image including a region where a color is developed by subtractive color mixture by superposition of two or three colors of ink is obtained. The thermal transfer recording medium of the present invention can of course be applied to overprinting using heating means other than a thermal head, for example, laser irradiation.

[0035]

Next, the present invention will be described with reference to examples.

Example Yellow, magenta and cyan inks having the compositions shown in Table 2 were prepared. Each ink was prepared by mixing and dispersing the materials for 3 hours using a dispersing machine (ball mill) heated to 90 ° C.

With respect to the obtained three kinds of inks, the transmittance and the 70% cumulative particle size of the pigment contained therein (mean the particle size at which the cumulative% becomes 70% in the particle size distribution) were measured. The transmittance was measured using a UV IDEC-610 manufactured by JASCO Corporation and determined as a value when the thickness was 0.6 μm. Cumulative 70% particle size is SALD-1 manufactured by Shimadzu Corporation
It measured using 100. Table 2 shows the results.

[0038]

[Table 2]

Each of the above-mentioned inks was coated on a surface opposite to the stick prevention layer of a 3.5 μm thick polyethylene terephthalate film provided with a stick prevention layer made of a silicone resin having a thickness of 0.2 μm on one side by a hot melt method. Three types of thermal transfer recording media were prepared by coating to a thickness of 0.6 μm.

Using the obtained three types of thermal transfer recording media,
White PE with thermal printer (prototype) under the following printing conditions
A color image is formed by overlaying yellow, magenta, and cyan inks on T paper (a white polyethylene terephthalate film having a thickness of 75 μm and having an image receiving layer formed on one surface thereof, CH-885 manufactured by Seiko Denshi Kogyo KK). Formed.

Printing conditions Printing energy: 0.3 mJ / dot Printing speed: 3.5 msec / line The obtained image was of high density and high definition.

Comparative Example An ink having the composition shown in Table 3 was prepared. Each ink was prepared by dissolving a resin and a wax in toluene, adding a pigment thereto, and mixing and dispersing with a disperser (paint shaker) for 1 hour.

The transmittance and the 70% cumulative particle size of the obtained three kinds of inks were measured in the same manner as in the examples. Table 3 shows the results.

[0044]

[Table 3]

Each of the inks was coated on the same base film as used in the examples and dried to form an ink layer having a thickness of 0.6 μm, thereby producing three types of thermal transfer recording media.

Using the obtained three types of thermal transfer recording media,
When yellow, magenta, and cyan inks were overprinted in the same manner as in the example, print blur occurred and white PE was printed.
The ink was not successfully transferred onto the T paper.
Next, the printing energy was increased to 0.6 mJ / dot, and printing was performed repeatedly. However, the sharpness of the edge of the image was lacking due to the difficulty in cutting the ink layer, and a high-definition image was not obtained.

[0047]

According to the thermal transfer recording medium using the wax-based thin film ink layer of the present invention, a high-density and high-definition color image can be obtained as compared with a conventional thermal transfer recording medium using a resin-based thin film. Further, printing can be performed with printing energy that cannot be printed in the conventional example.

Claims (4)

[Claims] 1. A heat-sensitive transfer ink layer on one side of a substrate,
The thermal transfer ink layer has a pigment content of 25 to 60% by weight and a melting point of 6%.
Thermal transfer recording comprising 20 to 75% by weight of waxes in the range of 0 to 110 ° C and 0 to 15% by weight of the thermoplastic resin, and having a film thickness in the range of 0.2 to 1.0 µm. Medium. 2. The thermal transfer recording medium according to claim 1, wherein the pigment is dispersed in the ink layer in a state where 70% or more of the pigment particles have a particle size of 1.0 μm or less. 3. The heat-sensitive transfer ink layer has a hue of yellow, magenta or cyan, and the transmittance of the ink layer of each hue is 62% or more.
Or the thermal transfer recording medium according to 2. 4. The wax contains one or more selected from the group consisting of α-olefin / maleic anhydride copolymer wax, oxidized wax, candelilla wax, carnauba wax, montan wax and synthetic ester wax. 4. The heat-sensitive transfer recording medium according to claim 1, wherein the heat-sensitive transfer recording medium comprises: