JPH058118B2 - - Google Patents

Description

[Detailed description of the invention]

[Table of Contents] ●Overview ●Field of industrial application ●Prior technology ●Problems to be solved by the invention ●Means for solving the problems ●Action ●Examples ●Effects of the invention [Summary] Repeatable thermal transfer In ink sheets, in order to obtain good printing even on recording paper with poor surface smoothness, it is used as a heat-melting material that is solid at room temperature.
By adding at least two or more of fatty acid amide wax, ester wax, and fatty acid to a wax-like compound having a urethane bond,
Improves the adhesion of ink to recording paper, and
A thermal transfer ink sheet that reduces the melt viscosity of the ink to obtain good repeat printing even on low-smooth paper. [Industrial Application Field] The present invention is used in recording devices such as thermal transfer printers and facsimile machines, and the heat-melting ink is melted by the heat of the thermal head and transferred little by little onto recording paper, thereby printing the same spot. Viscosity can also be used,
This invention relates to a heat transfer ink sheet that can be used repeatedly. Since thermal transfer ink sheets currently on the market are disposable, there is a demand for thermal transfer ink sheets that are low in running cost and can be used repeatedly. In addition, with current recording devices, in order to obtain good printing, it is necessary to select recording paper with a good surface smoothness (Beck smoothness: 200 seconds or more).
It is desired to be able to perform good printing even in seconds). [Prior art] In conventional thermal transfer ink sheets, in order to obtain good printing even on recording paper with poor surface smoothness, the resin component in the ink layer is increased to increase the adhesiveness with the recording paper. There are known methods of transferring images by adding cross-linking properties or by imparting cross-linking properties. Furthermore, in terms of the printing mechanism, the pressure of the thermal head was increased, the timing and angle of peeling off the ink ribbon and recording paper after transfer were devised, and the shape of the thermal head was adjusted to make the ink ribbon and recording paper more effective. Attempts have been made to improve the structure by creating a protruding structure that makes contact with the surface. [Problems to be solved by the invention] The conventional thermal transfer ink sheet has low sensitivity because the ink layer contains a large amount of high-melting point resin component, and requires a lot of printing energy to obtain good printing. It is said that This places a heavy burden on the thermal head, posing a problem in terms of its lifespan. Furthermore, conventional thermal transfer ink sheets have the drawback of high running costs because they cannot be used repeatedly in principle. Furthermore, special printing mechanisms (conditions) are required,
There are some problems that cannot be directly applied to current printers. Furthermore, in conventional heat transfer ink sheets that can be used repeatedly, since the same location is used many times, the thickness of the ink layer is 3 to 5 times thicker than that of a disposable heat transfer ink sheet. Therefore, the sensitivity is low and a large amount of printing energy is required. Particularly at low temperatures, good printing cannot be achieved unless conditions exceed the thermal head's rating.
In addition, as mentioned above, when printing repeatedly on recording paper with poor surface smoothness, since the ink is endowed with resin properties such as film-forming ability and adhesiveness, the melting point Current thermal heads, which tend to have higher melt viscosity, have a problem that cannot be addressed if the ambient temperature is also taken into consideration. The present invention was made in view of the drawbacks of the prior art described above, and it is an object of the present invention to provide a thermal transfer ink sheet that enables good quality printing even on recording paper with poor surface smoothness. [Means for solving the problem] In order to achieve the above object, in the first invention of the present application, an intermediate adhesive layer is provided on the base material, and a coloring material, a filler material, and a heat absorbent layer, which is solid at room temperature, are provided on the base material. In a reusable heat transfer ink sheet provided with a meltable ink layer made of a meltable material, the heat meltable material is a wax-like compound having a urethane bond, and the least of three of fatty acid amide wax, ester wax, and fatty acid. Both are characterized by being a mixture of two or more materials. In addition, in the second invention of the present application, an intermediate adhesive layer is provided on the base material, and a heat-melt ink layer consisting of a coloring material, a filler, and a heat-melt material that is solid at room temperature is provided thereon. In the heat transfer ink sheet that can be used, the heat-melting material has at least a wax having a urethane bond and an alkyl group having 14 carbon atoms.
It is characterized by consisting of ~22 fatty acids. Furthermore, in the third invention of the present application, an intermediate adhesive layer is provided on the base material, and an ink layer comprising a coloring material, a filler, and a heat-melting material whose main component is a wax-like compound having urethane bonds thereon. A reusable thermal transfer ink sheet is characterized in that a plasticizer is added to the ink layer. [Function] By using the above-mentioned heat-melting material as the main component, it is possible to reduce the melt viscosity of the ink while maintaining the film-forming ability and adhesive properties of the urethane wax. Good printing can also be obtained on paper. In addition, the ink composition of the present invention is filled in the gaps in the stone wall-like structure constructed by the filler, and is melted by the heat of the thermal head and gradually oozes out from between the stone walls, making it easy to use repeatedly. It is possible to obtain clear printing without background smearing even during repeated printing. In addition, by adding a plasticizer, the melt viscosity of the urethane wax can be reduced without impairing its film-forming ability and adhesion, resulting in improved sensitivity and peelability even at low temperatures of, for example, 10°C. Good repeated printing can be obtained on recording paper with poor surface smoothness without causing any transfer. [Example] FIG. 1 is a sectional view of a main part of a thermal transfer ink sheet according to the present invention. For example, an intermediate adhesive layer 22 made of polyester resin and polyamide resin is placed on a base material 21 made of a polyester film with a thickness of 6 μm.
is provided with a thickness of 3 μm. A heat-fusible ink layer 23 is provided on the intermediate adhesive layer 22, which includes a coloring material, a filler, and a heat-fusible material that is solid at room temperature. Example: An intermediate adhesive layer made of polyester resin and polyamide resin was provided to a thickness of 3 μm on a 6 μm thick polyester film with a heat-resistant treatment layer on the back side.
Furthermore, on top of this, an ink layer consisting of the following ingredients is applied.
A thermal transfer ink sheet with a thickness of 10 μm was prepared. Coloring material: Cassette Black (manufactured by Nippon Kayaku)
1 part by weight Urethane wax: Urethane wax (manufactured by NOF) 2 parts by weight Fatty acid amide wax: Diamond-200 (Oleic acid amide, manufactured by Nippon Kasei) 0.5 part by weight Ester wax: Carnauba wax (manufactured by Nikko Fine Products) 0.5 Auxiliary material by weight: Parafin wax (145〓, manufactured by Nikko Fine Products) 0.5 part by weight Filler: Carbon black (manufactured by Nippon Kayaku)
0.5 parts by weight The thermal transfer ink sheet thus obtained was slit into a ribbon with a width of 8 mm, and a thermal transfer printer was used to print the sheet with an applied pulse width of 1.0 ms and an applied energy of 30 m.
Transfer recording was performed at J/mm ² . The recording paper used was Xerox paper (Kishu Paper, type PA4, Beck smoothness 50-70 seconds). A transfer density (Optical Density, OD) of 1.0 or higher was obtained, and a homogeneous transfer image without white spots was obtained even on Xerox paper. Moreover, even in repeated printing, clear printing without background smearing was obtained. In this example, instead of Diamond-200, erucic acid amide (Nippon Oil Co., Ltd.'s Alflo P-10, etc.), N-stearyloleic acid amide (Nippon Kasei Co., Ltd.'s Nikkaamide SO, etc.), ricinoleic acid amide (Nippon Kasei Co., Ltd.'s Diamond H A similar evaluation using a fatty acid amide wax such as (e.g.) revealed that good printing was obtained. In addition, similar evaluations were made using ester waxes such as beeswax, stearyl behenate (manufactured by NOF), and sucrose fatty acid esters (manufactured by Daiichi Kogyo Seiyaku, such as Sugar Wax FA-10E) instead of carnauba wax. As a result, good printing was obtained. Example Instead of the fatty acid amide wax in the example, myristic acid, palmitic acid, stearic acid, and behenic acid fatty acids (all manufactured by NOF) were used.
Thermal transfer ink sheets were produced in the same manner. As a result of evaluating these ink sheets in the same manner as in the examples, it was found that the transfer density was 1.0 or more, and even on Xerox paper, a homogeneous transferred image without white spots could not be obtained. Moreover, even in repeated printing, clear printing without background smearing was obtained. Example A thermal transfer ink sheet was prepared using the fatty acid used in the example instead of the ester wax used in the example, and the same evaluation was performed. In all combinations, the transfer density was 1.0 or higher, and the homogeneity on Xerox paper was also extremely good. Comparative Example The transfer characteristics of a thermal transfer ink sheet without the addition of fatty acid amide wax, ester wax, or fatty acid were such that the adhesive content of the urethane wax was too strong, causing white spots in the transferred image and causing problems in terms of homogeneity. It was hot. Additionally, when each is added individually, the homogeneity on Xerox paper improves, but
In the case of ester wax and fatty acid amide wax, peeling and transfer within the ink layer may occur, resulting in instability. This is because the melt viscosity of the ink hardly decreases even if ester wax or fatty acid amide wax is added. In the case of fatty acids, the melt viscosity of the ink decreased, but a transfer density of 1.0 or higher could not be obtained. The results of the above Examples and Comparative Examples are summarized in Table 1.

[Table] Example: On a 6 μm thick polyester film with a heat-resistant treated layer on the back side, an intermediate adhesive layer of 3 μm thickness made of polyester resin and polyamide resin was provided, and on top of this, a layer made of the following components was provided. A thermal transfer ink sheet having an ink layer with a thickness of about 10 μm was produced. Coloring material: Kayaset Black (manufactured by Nippon Kayaku Co., Ltd.)
1 part by weight Wax: Urethane wax (manufactured by NOF Corporation)
2 parts by weight fatty acid amide wax: Diamond-200
0.5 parts by weight Paraffin wax (145〓, manufactured by Nikko Fine Products Co., Ltd.) 0.5 parts by weight Filler: Carbon black (manufactured by Nippon Kayaku Co., Ltd.)
0.5 parts by weight Fatty acid: C ₁₄ - _{C 22} (manufactured by Nippon Oil & Fats Corporation) 0.5 parts by weight Fatty acids include myristic acid whose main component is C ₁₄ , palmitic acid whose main component is C ₁₆ , and stearin whose main components are C ₁₆ and C ₁₈ . The main component is behenic acid, _C22 . These fatty acids may be used alone or in combination. In this example, the thermal transfer ink ribbon used alone (slitted to a width of 8 mm) was printed using a thermal transfer printer.
Applied pulse width 1ms, applied energy 30mJ/mm ²
The transcription was recorded. The recording paper used was Xerox paper (Kishu Paper, type PA4, Beck smoothness 50-70 seconds). No matter which fatty acid was used, a transfer density (Optical Density, OD) of 1.0 or more was obtained, and a homogeneous transfer image without white spots was obtained even on Xerox paper. When fatty acids were not added, the homogeneity on Xerox paper decreased, and peeling and transfer could occur within the ink layer, resulting in instability. When the number of carbon atoms in the alkyl group of the fatty acid is C ₁₂ or less (for example, lauric acid whose main component is C ₁₂ ), the melting point is as low as 50° C. or less, which causes background smearing due to scratch transfer during printing. Conversely, when the alkyl group of the fatty acid has a carbon number of _C24 or more (for example, lignoceric acid), the melting point is too high, resulting in a disadvantage that the energy required for recording increases. FIG. 2 shows the melt viscosity characteristics of an ink that supports the effects of the present invention, using stearic acid as an example. By adding fatty acids,
In particular, the viscosity at low temperatures is significantly reduced. Example An intermediate adhesive layer of 3 μm thick made of polyester resin and polyamide resin was provided on a 6 μm thick polyester film with a heat-resistant treated layer on the back side, and an ink layer made of the following components was further applied on top of this. A thermal transfer ink sheet with a thickness of 10 μm was prepared. Coloring material: Kayaset Black (manufactured by Nippon Kayaku)
1 part by weight Tsukusu: Urethane wax (manufactured by NOF)
2 parts by weight Diamond 0-200 (manufactured by Nippon Kasei) 0.5 parts by weight Paraffin wax (manufactured by Nippon Seiro) 1 part by weight Filler: Carbon black (manufactured by Nippon Kayaku)
0.5 parts by weight Plasticizer: (manufactured by Daihachi Chemical) 0.3 parts by weight As for plasticizers, phthalate esters include dioctyl phthalate and diisodecyl phthalate,
Thermal transfer ink sheets were prepared using dioctyl azelate dibutyl sebacate as the fatty acid ester, dibutyl maleate and dioctyl fumarate as the maleic acid/fumaric esters, and tributyl phosphate and trioctyl phosphate as the orthophosphoric esters. These were slit into ribbons with a width of 8 mm, and transfer recording was performed using a thermal transfer printer with an applied pulse width of 1 ms and applied energy of 30 mJ/mm ² . The recording paper used was Xerox paper (Kishu Paper, type PA4, Beck smoothness).
50-70 seconds). As a result of transfer recording performed at an ambient temperature of 5 to 40°C, good printing was obtained without peeling and transfer at low temperatures, regardless of which plasticizer was used. Furthermore, even at high temperatures, clear prints were obtained without background smearing due to repeated printing. FIG. 3 shows the temperature characteristics when tributyl phosphate is added. It can be seen that the characteristics at low temperatures are significantly improved compared to when it is added. Figure 4 takes tributyl phosphate as an example.
This figure shows the dependence on the amount added. The amount of tributyl phosphate is 3wt% based on the total ink components.
If the amount is less, there is no effect of the addition. Furthermore, as the amount added was increased, the transfer density decreased, but the homogeneity of the transferred image on recording paper with poor surface smoothness improved. However, if the amount added exceeds 15wt%,
There was a problem with storage stability at high temperatures. Therefore, the preferable addition amount is 3 to 15 wt%.
It is. [Effects of the Invention] According to the present invention, without impairing the excellent properties (film forming ability, adhesiveness) of urethane wax,
Since the melt viscosity of the ink can be reduced, good printing can be obtained even on recording paper with poor surface smoothness. Moreover, even in repeated printing, clear printing without background smearing can be obtained. In addition, by adding a plasticizer, the melt viscosity of the ink can be reduced without impairing the excellent film-forming ability and adhesive properties of urethane wax, so it can be used without peeling transfer even at low temperatures. You can get good printing results.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a thermal transfer ink sheet according to the present invention, FIG. 2 is a melt viscosity characteristic diagram showing the effects of the embodiment, and FIGS. 3 and 4 are temperature characteristic diagrams showing the effects of the embodiments. and is a graph showing the transfer density versus the amount of plasticizer added. 21...Substrate, 22...Intermediate adhesive layer, 23...
Hot melt ink layer.

Claims (1)

[Claims] 1. Repeated use in which an intermediate adhesive layer 22 is provided on a base material 21, and a thermofusible ink layer 23 consisting of a coloring material, a filler, and a thermofusible material that is solid at room temperature is provided thereon. A possible thermal transfer ink sheet is characterized in that the heat-melting material is a mixture of a wax-like compound having a urethane bond and at least two or more materials among fatty acid amide wax, ester wax, and fatty acid. A thermal transfer ink sheet. 2 The fatty acid has an alkyl group having 14 to 22 carbon atoms.
The thermal transfer ink sheet according to claim 1, characterized in that: 3 An intermediate adhesive layer 22 is provided on a base material 21, and an ink layer 23 consisting of a coloring material, a filler, and a heat-melting material whose main component is a wax-like compound having a urethane bond is provided on the intermediate adhesive layer 22, which can be used repeatedly. A thermal transfer ink sheet, characterized in that a plasticizer is added to the ink layer. 4. The thermal transfer ink sheet according to claim 3, wherein the plasticizer comprises at least one of phthalic acid ester, fatty acid ester, maleic acid/fumaric acid ester, and orthophosphoric acid ester. 5. The thermal transfer ink sheet according to claim 3 or 4, wherein the plasticizer is added in an amount of 3 to 15 wt% based on the total ink components.