JPH02286291A - Thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To transfer ink even to rough paper low in smoothness with high transfer efficiency by forming an ink layer into such a structure that a porous elastomer is filled with a definite amount of ink. CONSTITUTION:A thermal transfer recording medium is constituted of at least a heat- resistant support 4 and a thermoplastic ink layer and the ink layer consists of a porous body 1 having a thickness of 3mum or more and proper elasticity and the thermoplastic ink contained in the voids 2 of the porous elastomer in a void volume ratio of 20 - 90%. The porous elastomer 1 is fixed to the heat-resistant support 4 and not released from the heat-resistant support 4 at the time of the melting of the thermoplastic ink under heating. When the thermal transfer recording medium is pressed to rough paper, the porous elastomer 1 is compressed by the protruding surface of the paper and becomes a state in contact with paper nap in the recessed surface thereof as it is. When the heater of a thermal head is pressed to the part positioned at the recessed parts of the paper in this state, the ink layer 2 is melted at the heating part of the thermal head and propagated through the surface part of the porous elastomer to reach paper nap. Further, the ink contained in the porous elastomer is precipitated from the pores thereof and reaches the surface of the paper to form a dot.

Description

[Detailed Description of the Invention] [Industrial Field of Application] [Prior Art] In recent years, thermal transfer recording has the characteristics of being non-impact, noiseless, maintenance-free, low cost, compact and lightweight, and capable of color printing. It is used in the fields of facsimiles, computer terminals, recorders, etc.

Such a thermal transfer recording method melts and transfers ink onto a recording paper by heating the surface of the recording material with a thermal head or by heating an energized heat-generating resistive layer with a current-carrying head.
It provides printing or images, and the structure of the thermal transfer recording material includes a base material, a heat-melting ink layer, and, if necessary, an ink release layer between the ink layer and the base material for the purpose of improving transferability. , a structure in which a heat-resistant protective layer for the purpose of preventing sticking of the thermal head or an adhesive layer is provided on the ink layer is common. FIG. 4 shows the structure of a conventional thermal transfer recording material.

However, when plain paper is used as the transfer paper, the transferability of this thermal transfer recording method is greatly influenced by the physical properties of the irregularities on the surface of the plain paper, the adhesive strength of the ink layer, the permeability, etc. Particularly in the case of paper with large surface irregularities, the thermally molten ink adheres only to the convex portions or the vicinity thereof, resulting in parts of the printed image being chipped off and degrading the print quality.

As a means to solve the above problems, for example,
As shown in JP-A No. 0-264291, JP-A-60-264295, JP-A-61-244590, etc., the ink layer or release layer contains a thermally decomposable or thermally expandable foaming agent. As shown in JP-A-63-67178 and JP-A-63-78792, an image forming element in which a thermal transfer recording material is coated with a heat-melting coating material is thermally fused onto a base material. Alternatively, a technique has been devised in which the binding material is exposed.

[Problems to be solved by the invention] However, the aforementioned thermal transfer recording materials containing a thermal foaming agent have problems such as low thermal responsiveness of the foaming agent (uniform transfer to paper cannot be achieved, and high energy is required). In addition, thermal transfer recording materials in which the image forming element is thermally fused onto the base material or exposed from the binder have poor adhesion of the image forming material containing the coloring material, and the background may be damaged during transfer. The problem was that it caused dirt.

Therefore, the present invention was made in view of solving the above-mentioned problems, and its purpose is to provide an ink containing a coloring material with excellent adhesion and no background smearing (and with excellent transferability). An object of the present invention is to provide a thermal transfer recording material with excellent printing quality and images, and a method for manufacturing the same.

[Means for Solving the Problems] The thermal transfer recording medium of the present invention comprises at least a heat-resistant support;
a thermoplastic ink layer, the ink layer comprising:
A porous body having a thickness of 5 μm or more and moderate elasticity, and a pore volume ratio of 20 to 9 in the pores of the porous elastic body.
The ink layer is characterized by comprising a thermoplastic ink having a content of 0%.

Furthermore/or, the porous elastic body is fixed to a heat-resistant support and is characterized in that it does not separate from the heat-resistant support when the thermoplastic ink is heated and melted.

[Operations] The surface roughness of paper, which is generally referred to as rough paper, is such that the depth of the grooves is 20 to 40 μm and the width of the grooves is approximately 200 μm. With conventional ink films, it was impossible to transfer only one dot into a deep and wide groove. The relationship is shown in Figure 5. In the figure, 5 is the paper surface, and the blacked area is one dot. As is clear from the figure, there is a high probability that the ink melted part will not come into contact with the paper, resulting in voids and white spots.

The principle of the thermal transfer medium of the present invention is shown in FIG. Figure 2 shows
A state diagram of the thermal transfer medium of the present invention pressed onto rough paper,
The porous elastic body 1 is compressed on the convex surface of the paper, remains unchanged on the concave surface, and is in contact with the paper fluff appearing on the concave surface of the paper. In this state, when the thermal head heating element is pressed against the part of the paper that is located exactly in the recess, the ink layer 2 is melted by the heating part and flows along the surface of the porous body to reach the paper fluff. Furthermore, the ink contained within the porous body naturally precipitates from the pores.The molten ink travels along the paper fluff and reaches the paper surface, making it possible to form dots that are also transferred to the concave surface.

[Example] An example of the present invention is shown in FIG. The figure is a cross-sectional structural diagram of a thermal transfer recording medium according to the present invention. In the figure, 1 is a porous elastic body, 2 is a pore filled with thermoplastic ink or not filled, 3 is an intermediate layer for fixing the porous elastic body, and 4 is a heat-resistant support.

The support is preferably one that has heat resistance, mechanical strength, and high smoothness. The material is preferably a resin film such as polyethylene, polypropylene, polyester, polyimide, polyether sulfone, or polyethylene terephthalate, and has a thickness of 1 to 60 μm, preferably 1 to 15 μm.

The thermoplastic ink layer contains, in addition to pigments and/or dyes, binders such as paraffin wax, microcrystalline wax, cal, napa wax, oxidized wax, candelilla wax, montan wax, Fischer-Tropsch wax, alpha-olefin/maleic anhydride. Acid copolymer.

Fatty acid amide, fatty acid ester, distearyl ketone,
polyethylene resin, ethylene-vinyl acetate copolymer,
Suitable are organic substances exhibiting thermoplasticity such as ethylene-ethyl acrylate copolymer epoxy resin, or a mixture thereof.

In addition, as porous elastic bodies, polyurethane, polystyrene, polyvinyl chloride, polyolefin, epoxy resin,
Any one of elastic foam forming materials such as polyvinyl alcohol, viscose sponge, natural rubber, neoprene, SBR, NBR, silicone resin, or a mixture thereof is suitable.

Further, as the intermediate layer, a resin having good adhesive properties such as EvA resin, or a mixture thereof partially mixed with wax is suitable.

Using a PE1T film 4.0μ'' product as a heat-resistant support, first, EVA resin was used as an intermediate layer, and toluene/M
After diluting 4 times (volume ratio) with EK solvent and stirring thoroughly,
It was coated to a thickness of 1 μm using a solvent coater.

Next, diisocyanate and polyol are reacted to create a prepolymer, and a catalyst and blowing agent are added at the time of coating.
A μm thick polyurethane foam was formed on the intermediate layer.

Thereafter, an ink having the following composition was applied under pressure using a solvent method, and the pressure was adjusted so that the porosity was 50%.

Ink layer composition Weight% Carbon black 20% Paraffin wax 45% Microcrystalline wax 15% Polyurethane resin 5% ET
Resin A 10% Using the above example, a transfer experiment was conducted on rough paper in comparison with a general commercially available product. The thermal head used was 300 dpi
t Applied energy 0, 12 mj/dot, printing cycle 5.0 m sse p Transfer paper is Southworth 40
50 paper (Beck smoothness 8 sec) and Xerox 4024 paper (Beck smoothness 15-20 sec)
was used. The transcription results are shown in Table 1.

Table 1 [Effects of the Invention] As explained above, the inline layer has a structure in which a porous elastic body is filled with a certain amount of ink, so that high transfer rate can be achieved even on so-called rough paper with low smoothness. It became possible to transfer with high efficiency. The present invention greatly contributes to improving the quality of printouts using thermal technology, and its effects are tremendous.

As is clear from the table, we were able to see a significant improvement over rough paper.

Note that the present invention is not limited to these specific examples,
Needless to say, many different combinations are possible.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional packing diagram of the thermal transfer recording medium of the present invention. FIG. 2 is an explanatory diagram of the state 7 in contact with paper. FIG. 3 is a cross-sectional structural diagram of a conventional thermal transfer recording medium. It is a transcription|transfer schematic diagram. 1...Porous elastic body 2...Vacancies (filled with ink or unfilled) 3
......Intermediate layer 4...Heat-resistant support 5...Rough paper 6...Rough paper surface Paper fluff...
...Thermal head heating element...Top layer...Conventional ink layer...Conventional middle layer

Claims (2)

[Claims] (1) In a thermal transfer recording medium comprising at least a heat-resistant support and a thermoplastic ink layer, the ink layer comprises a porous body having a thickness of 3 μm or more and having appropriate elasticity, and a porous elastic body. A thermal transfer recording medium comprising a thermoplastic ink having a pore volume ratio of 20 to 90% in pores. (2) the porous elastic body is fixed to a heat-resistant support;
2. The thermal transfer recording medium according to claim 1, wherein the thermoplastic ink does not separate from the heat-resistant support when the thermoplastic ink is heated and melted.