JPH05270155A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To enhance resolving power and high speed followability by coating the surface of a hot-melt ink layer consisting of an isocyanate polymer of lanolin fatty acid/polyhydric alcohol ester having specific melt viscosity, a predetermined amount of a ethylene/vinyl acetate resin and a predetermined amount of a coloring component with layer having flocculation force larger than that of the ink layer. CONSTITUTION:A thermal transfer ink layer wherein a coloring component such as carbon block and an ethylene/vinyl acetate resin contained in a binder excepting the coloring component in an amount of 15-60wt.% are added to an isocyanate polymer of lanoline fatty acid/polyhydric alcohol ester having melt viscosity of 3000-50000cSt at 100 deg.C is formed on a base material such as condenser paper through a wax release agent composed of carnauba wax. The surface of the ink layer is further coated with a coating layer having flocculation force larger than that of the ink layer and composed of an ethylene/ vinyl acetate copolymer resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording medium, and more particularly to a thermal transfer recording medium which has high sensitivity and can realize high resolution printing on a rough surface paper such as copy paper.

[0002]

2. Description of the Related Art In a thermal transfer recording system, a thermal transfer recording medium is used in which at least one layer of thermal melting ink is applied onto a base material on a sheet. Is a recording system in which the ink layer is heated and melted by a heating head from the base material side of the thermal transfer recording medium to obtain a transfer image on the transfer paper. According to this method, the device used is low in noise, excellent in operability and maintainability, and plain paper can be used as the transfer target paper, and thus has been widely used in recent years.

[0003]

As the performance of thermal transfer printers has been improved, complex functions such as high-speed printing on rough surface paper have been required. When considering the speedup of printers, high-speed followability (higher sensitivity) of the ribbon becomes a major issue. Higher sensitivity has been achieved by using a wax with a low melting point, but the printing on rough-surfaced paper is poor due to poor coverage or the paper has poor resolution due to penetration. It was further,
To improve high-speed followability while keeping the rough surface paper coating,
Conventionally, the resin component was introduced into the binder (Japanese Patent Laid-Open No. 54-8723).
No. 5, No. 54-163044, No. 56-98269, No. 62-130887
No.) etc. have been dealt with, but none of them satisfy the complex requirements in a balanced manner. Therefore, an object of the present invention is to provide a thermal transfer recording medium having a good resolution (covering) on a rough surface paper and capable of printing at a high speed following property.

[0004]

Means for Solving the Problems As a result of earnest studies, the present inventors have found that hot-melting of an incyanate polymer of lanolin fatty acid polyhydric alcohol ester having a specific melt viscosity and ethylene vinyl acetate resin in a specific ratio. A heat-meltable ink layer is formed on a substrate via a wax release layer, and a coating layer having a cohesive force larger than that of the heat-meltable ink layer is provided on the surface of the heat-meltable ink layer. As a result, it was confirmed that the above objects can be achieved, and the present invention has been completed.

That is, according to the present invention, (a) an isocyanate polymer of a lanolin fatty acid polyhydric alcohol ester having a melt viscosity of 3000 to 50,000 cSt at 100 ° C. (b) an ethylene vinyl acetate resin in a binder excluding coloring components 60% by weight, and further (c) a coloring component is added as an essential component to form a thermal transfer ink layer on a substrate via a wax release layer, and on the surface of the heat-meltable ink layer, A cohesive force larger than the cohesive force (F ₁ ) of the heat-meltable ink layer
The present invention provides a thermal transfer recording medium characterized in that a coating layer having (F ₂ ) is provided.

The isocyanate polymer of lanolin fatty acid polyhydric alcohol ester used in the present invention is obtained by saponifying and decomposing lanolin secreted from sebum lines of sheep, and lanolin fatty acid, glycerin, pentaerythritol, trimethylolpropane and the like. It is obtained by crosslinking the esterification reaction product with a polyhydric alcohol with an isocyanate such as tolylene diisocyanate (TDI) or diphenylmethane 4,4′-diisocyanate (MDI). Of these, in the present invention, it is necessary to use a lanolin fatty acid polyhydric alcohol ester isocyanate polymer having a melt viscosity at 100 ° C. of 3000 to 50,000 cSt. The melt viscosity at 100 ° C
If a polymer of less than 3000 cSt is used, the cohesive force is weak as in the case of wax, and the ink does not cover the rough surface paper poorly. On the other hand, when a lanolin fatty acid polyhydric alcohol ester isocyanate polymer having a viscosity of more than 50,000 cSt is used, the ink is not easily cut and the ink has a low resolution in high-speed printing.

The ethylene vinyl acetate resin used in the present invention is a copolymer of ethylene and vinyl acetate, and has a molecular weight of
It can be used regardless of the vinyl acetate ratio. The optimal blending amount of ethylene vinyl acetate resin is 15 to 60% in all ink binders excluding coloring components. If the blending amount is less than 15%, problems such as scumming will occur. On the contrary, if the blending amount exceeds 60%, sensitivity and ink shortage will be poor and high-speed printing will result in low resolution ink.

The ink binder for the heat-meltable ink layer according to the present invention includes waxes such as paraffin wax, carnauba wax, candelilla wax, beeswax, wood wax, low molecular weight polyethylene wax, α-olefin oligomer and montan wax. Ingredients or petroleum resin,
It is also possible to use resin components such as ethylene-acrylic acid copolymer, polyethylene, and acrylic resin in combination. Further, it is also possible to add an optional component such as a dispersant which is usually added to the hot melt ink.

The hot-melt ink layer according to the present invention comprises the above ink binder component and a coloring component as essential components. As the coloring component, any coloring component having coloring ability can be used. For example, black dyes and pigments such as carbon black, oil black, graphite, CI Pigment Yellow1, ibid 3, ibid 74, ibid 97, ibid 98
Acetoacetic acid arylamide monoazo yellow pigments (fast yellow), CIPigment Yellow12, 13 and 14 acetoacetic arylamide bisazo yellow dyes, CIPigm
Yellow pigments such as ent Yellow19, 77, 79, CIDisperse Yellow164, CI Pigment Red48, 49: 1, 53: 1, 5
7: 1, 81, 122, 5 etc. red or red pigment, CIS
Red pigments such as olvent Red52, 58, 8 etc., CI Pigment
Copper phthalocyanine and its derivatives such as Blue 15: 3 and blue dyes and pigments such as modified products can be used. Furthermore, dyes and pigments well known in conventional printing inks and other coloring applications such as colored or colorless sublimable dyes can be used. The blending amount is not particularly limited, but 10 to 60% is optimal.

In the thermal transfer recording medium of the present invention, a coating layer is formed on the surface of the above heat fusible ink layer.
The cohesive force (F ₂ ) of the coating layer must be larger than the cohesive force (F ₁ ) of the hot-melt ink layer. In the present invention, the cohesive force between the hot-melt ink layer and the coating layer is measured as follows. First, the cohesive force (F ₁ ) of the heat-fusible ink layer was measured by adhering an adhesive tape on the ink layer formed on the substrate and using a tensile strength tester (Tensilon RTM-100 type manufactured by Toyo Baldwin Co., Ltd.). The force when peeling the support from the adhesive tape at a peeling angle of 180 degrees at a temperature of 25 ° C and a peeling speed of 300 mm / min is converted into 1 cm width. The cohesive force (F ₂ ) of the coating layer is measured in the same manner as the cohesive force of the ink by adhering an adhesive tape on the coating layer formed on the surface of the heat-meltable ink layer and using a tensile strength tester. The coating layer provided on the surface of the heat-meltable ink of the present invention includes polyethylene, ethylene vinyl acetate copolymer resin and its modified products, ethylene / acrylate copolymer, ionomer resin, polyamide resin, nylon resin, polyester resin, polypropylene. Resin or the like is used. The above resins may be used alone or in combination of two or more. Further, in order to improve the wettability with respect to the transferred material, rosin, rosin derivative, terpene, modified terpene resin, aliphatic petroleum resin, aromatic petroleum resin, water-added and copolymerized petroleum resin, dicyclopentadiene-based Petroleum resin, coumarone-indene resin, styrene resin, and isoprene resin may be added. In addition, paraffin wax, microcrystalline wax, Fischer-Tropsch wax,
Waxes such as various low molecular weight polyethylene waxes, modified waxes and atactic polypropylene may be added.

In the thermal transfer recording medium of the present invention, it is essential to provide a wax-based release layer between the substrate and the heat-meltable ink layer. Examples of the wax used in the wax-based release layer include microcristan wax, carnauba wax,
One or more selected from the group consisting of candelilla wax, rice bran wax and oxidized polyethylene wax are preferable. In addition to waxes, resins such as ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, polyethylene and petroleum resin may be added to improve the coating strength. By providing the wax-based release layer between the base material and the heat-meltable ink layer, a high-quality transferred image with high sensitivity can be obtained.

The base material of the thermal transfer recording medium of the present invention includes:
Papers such as capacitor paper and glassine paper, thin films such as polyesters such as polyethylene terephthalate, polyimides such as polyimide, polycarbonate, polyamide, polyethylene and polypropylene, and films are used. The thickness of the substrate is preferably in the range of about 2-20 μm. When recording is performed using a thermal head or the like, in order to improve heat resistance and runnability on the side of the substrate that contacts the thermal head, silicone-based or fluorine-based compounds, resin layers, crosslinked polymer layers, metal layers May be provided. In particular, in order to sufficiently bring out the performance of the lanolin fatty acid polyhydric alcohol ester isocyanate polymer-based ink of the present invention, it is more preferable to use a silicone-modified acrylic resin or silicone-modified ester resin.

[0013]

According to the present invention, there is provided a well-balanced thermal transfer recording medium having a film-forming property capable of coating a rough surface paper, ensuring transferability and resolution. The thermal transfer recording medium of the present invention is capable of high-sensitivity and high-resolution printing on rough paper such as copy paper even when printed by a high-speed printer of about 100 characters / sec. Shows good performance.

[0014]

EXAMPLES The effectiveness of the present invention will be illustrated below with reference to Examples, but the present invention is not limited to these.

Example 1 Rice bran wax was blended in toluene at a composition ratio shown in column B of the blending table 1 so that the solid content concentration was 10%. This is dispersed by a ball mill for 12 hours to form a paint. This paint was treated with a silicone-based back coat using a wire bar coater to make PET with a thickness of 3.5 μm.
Apply it on the film to a dry weight of 0.7 g / m ² ,
A wax release layer is formed. Next, the melt viscosity at 100 ° C 4
Using 000 cSt of lanolin fatty acid polyhydric alcohol ester isocyanate polymer, it is blended in toluene at a composition ratio shown in column D of formulation table 2 so that the solid content concentration is 18%. This is dispersed with a ball mill for 12 hours to form an ink. This coating material is applied to the wax release layer side of the PET film coated with the wax release layer so as to have a dry weight of 2.5 g / m ² by using a wire bar coater to form an ink layer. Finally, using ethylene-vinyl acetate copolymer, at the composition ratio shown in the F column of the blending table 3, the solid content concentration
Blend in toluene to 10%. This is dispersed by a ball mill for 12 hours to form a paint. PE coated with an ink layer using a wire bar coater
The T film is coated on the ink layer side so as to have a dry weight of 0.7 g / m ² , and slit to a predetermined width to obtain a thermal transfer ink ribbon. When this ribbon was used to print with a commercially available Sharp Personal Word Processor WD-A561 (100 characters / sec), the results shown in Table 4 were obtained.

Example 2 Carnauba wax was blended in toluene at a composition ratio shown in column A of the blending table so that the solid content concentration was 10%, and the mixture was dispersed for 12 hours using a ball mill to prepare a coating. To do. Using a wire bar coater, this coating material is applied on a 3.5 μm PET film treated with a silicone-based back coat so that the dry weight becomes 0.7 g / m ² , and a wax release layer is formed. Next, using a lanolin fatty acid polyhydric alcohol ester isocyanate polymer having a melt viscosity of 5500 cSt at 100 ° C., it is blended in toluene at a composition ratio shown in column E of the blending table 2 so that the solid content concentration is 18%. This is dispersed with a ball mill for 12 hours to form an ink. This coating material is applied to the wax release layer side of the PET film coated with the wax release layer so as to have a dry weight of 2.5 g / m ² by using a wire bar coater to form an ink layer. Finally, a polyamide resin is blended in toluene at a composition ratio shown in column G of the formulation table 3 so that the solid content concentration is 5%. This is dispersed by a ball mill for 12 hours to form a paint. Using a wire bar coater, this coating material is applied to the ink layer side of the PET film coated with the ink layer so that the dry weight becomes 0.7 g / m ² , and slit to a predetermined width to obtain a thermal transfer ink ribbon. Using this ribbon, a commercially available Sharp Personal Word Processor WD-A56
When printed at 1 (100 characters / second), the results shown in Table 4 were obtained.

Comparative Example 1 Carnauba wax was blended in toluene at a composition ratio shown in column A of the blending table 1 to a solid content concentration of 10%, and dispersed for 12 hours using a ball mill to prepare a coating. To do. Using a wire bar coater, this coating composition is applied on a 3.5 μm PET film treated with a silicone-based back coat so that the dry weight becomes 0.7 g / m ² , and a wax release layer is formed. Next, using a lanolin fatty acid polyhydric alcohol ester isocyanate polymer having a melt viscosity of 4000 cSt at 100 ° C., it is blended in toluene at a composition ratio shown in column D of the blending table 2 so that the solid content concentration is 18%. This is dispersed with a ball mill for 12 hours to form an ink. This coating material is applied to the wax release layer side of the PET film coated with the wax release layer so as to have a dry weight of 2.5 g / m ² by using a wire bar coater to form an ink layer. Finally, using paraffin wax,
The composition ratio shown in the column is added to toluene so that the solid content concentration is 5%. This is dispersed by a ball mill for 12 hours to form a paint. Using a wire bar coater, this coating material is applied to the ink layer side of the PET film coated with the ink layer so that the dry weight becomes 0.7 g / m ² , and slit to a predetermined width to obtain a thermal transfer ink ribbon. Using this ribbon, a commercially available Sharp Personal Word Processor WD-
When printed with A561 (100 characters / second), the results shown in Table 4 were obtained.

Comparative Example 2 Using a lanolin fatty acid polyhydric alcohol ester isocyanate polymer having a melt viscosity of 5500 cSt at 100 ° C., the composition ratio shown in column E of the formulation table 2 was added to toluene so that the solid content concentration was 18%. Compound. This is dispersed with a ball mill for 12 hours to form an ink. Using a wire bar coater, coat this coating on a PET film with a thickness of 3.5 μm with a silicone back coat and dry weight of 2.5 g / m ²
To form an ink layer. Next, using an ethylene vinyl acetate copolymer, it is blended in toluene at a composition ratio shown in column F of the blending table 3 so that the solid content concentration is 10%. This is dispersed by a ball mill for 12 hours to form a paint. Using a wire bar coater, this coating material is applied to the ink layer side of the PET film coated with the ink layer so that the dry weight becomes 0.7 g / m ² , and slit to a predetermined width to obtain a thermal transfer ink ribbon. Using this ribbon, a commercially available Sharp Personal Word Processor WD-A561
When printed at (100 characters / second), the results shown in Table 4 were obtained.

Comparative Example 3 Microcrystalline wax was blended in toluene at a composition ratio shown in column C of the blending table 1 to a solid content concentration of 10%, and dispersed for 12 hours using a ball mill to prepare a coating composition. Turn into. This paint using a wire bar coater,
3.5μm PET treated with silicone type back coat
Apply it on the film to a dry weight of 0.7 g / m ² ,
A wax release layer is formed. Next, melt viscosity at 100 ° C 5
Using 500 cSt of lanolin fatty acid polyhydric alcohol ester isocyanate polymer, it is blended in toluene at a composition ratio shown in column E of the blending table 2 so that the solid content concentration is 18%. This is dispersed with a ball mill for 12 hours to form an ink. Using a wire bar coater, apply this coating material to the wax release layer side of the PET film coated with the wax release layer so that the dry weight will be 2.5 g / m ² and slit it to a predetermined width to transfer the thermal transfer ink. Get the ribbon. Using this ribbon, commercially available Sharp Personal Word Processor WD-A
When printed at 561 (100 characters / second), the results shown in Table 4 were obtained.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

[Table 4]

Here, each evaluation in Table 4 was performed by the following methods. (1) Sensitivity: Visual determination of dot pattern reproducibility ○: Reproducibility almost complete △: Poor reproducibility ×: Poor reproducibility (2) Resolution: Visual determination of reproducibility of 1-dot fine line ○: Reproducibility Nearly complete △: Inadequate reproducibility ×: Poor reproducibility (3) Covering: Visually determine solid black print reproducibility ○: Almost complete reproducibility △: Inadequate reproducibility ×: Poor reproducibility (4) Transferability: Visually judge the state of removal of the ink layer of the ink ribbon after printing. ○: Completely or almost completely removed △: If you look carefully, there is only a small portion but not removed × The part that has not been removed is clearly visible. (5) Robustness ... Solid black After printing, place the paper on it, and apply a pressure of about 150 g with a pencil (hardness H) on the paper to scratch it Visual inspection of scratches on the print ○: No scratches were found △: Partially scratched Existence of scratches is present.

As shown in Table 4, the thermal transfer recording medium of the present invention exhibits a printing quality that is extremely well balanced in terms of sensitivity, resolution, coating, etc., and sufficiently fulfills the original purpose.

Claims (2)

[Claims] 1. A melt viscosity at 100 ° C. is 3000 to 50.
(B) ethylene vinyl acetate resin to the isocyanate polymer of 000 cSt lanolin fatty acid polyhydric alcohol ester,
15-60% by weight in the binder excluding coloring components, and further (c)
A thermal transfer ink layer containing a coloring component as an essential component is formed on a base material via a wax release layer, and the heat-meltable ink layer has an aggregate on the surface of the heat-meltable ink layer. A thermal transfer recording medium provided with a coating layer having a cohesive force (F ₂ ) larger than the force (F ₁ ). 2. The wax component of the wax release layer is one or more selected from the group consisting of microcrystalline wax, carnauba wax, candelilla wax, rice bran wax and oxidized polyethylene wax. Thermal transfer recording medium.