JPH0158078B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel thermal recording medium that can be suitably used in thermal recording devices such as thermal facsimile machines. Recently, the development of facsimile communication has been remarkable, and thermal recording is a typical recording method used in facsimile devices. FIG. 3 is a schematic explanatory diagram showing an example of a facsimile device using thermal paper, a so-called thermal fax. In other words, the thermal paper 1 is pressed against the heating head 3 by the pinch roller 2, and while the thermal paper 1 is heated and colored, the pinch roller 2 feeds the thermal paper 1 at a certain pitch, and the resulting image is then cut out by the cutter 4. It is something that Such conventional heat-sensitive recording methods do not require development or fixing, and have the advantage of being excellent in reliability and maintainability. are doing. For this purpose, a heat-melting ink layer is coated on a thin film, plain paper is placed on the surface of the ink layer, and the film is heated from above with a heating head to melt the ink layer and transfer it to the plain paper.Thermal transfer A recording method is proposed. This recording method has the feature that recording can be performed on plain paper without sacrificing the advantages of conventional thermal paper recording methods. In such thermal transfer recording methods, polyester films have conventionally been used as the base film. However, if a thin polyester film with a thickness of about 10 μm is used in the facsimile device as described above, clear and high-resolution recording can be made, but wrinkles may occur due to shrinkage of the film, resulting in uneven recording or the inability to record. There are drawbacks. In addition, when using a thick film with a thickness of about 25 μm, wrinkles can be prevented, but in order to obtain a record of sufficient density, it is necessary to raise the heating temperature, which may cause the film to melt and cause the heating head to be heated. It has the disadvantage of adhering to. On the other hand, it has been proposed to use paper such as tissue paper instead of plastic film such as polyester film. Tissue paper itself has excellent heat resistance and has the advantage of not shrinking and wrinkled by contact with the heating head, nor sticking to the heating head. The disadvantages are that the melt transferability (releasability) of the ink layer deteriorates, the sharpness of the printed image is poor, and unevenness and chipping are likely to occur. Furthermore, since the hot-melt ink layer is applied onto the tissue paper, there is a disadvantage that the ink layer penetrates into the interior of the tissue paper, eventually reaching the back surface and contaminating the heating head. The present invention has been completed in order to eliminate the above-mentioned drawbacks, and the present invention has been completed by heating a hot-melt ink layer provided on a base material with a heating head from the back side of the base material. In a thermal transfer recording medium used in a recording method in which a portion is selectively transferred to a receptor to form a printed image, the base material is thin paper, and the heat-melting ink layer prevents ink from penetrating into the thin paper. The gist of the present invention is a thermal transfer recording medium containing a lubricant that can improve the releasability of the ink layer. The thin paper in the present invention has a basis weight of 10 to 30 g/
m ² thin paper, such as one-time carbon base paper, wax paper base paper, copy paper, typewriter base paper, etc. The thermal transfer recording medium of the present invention uses thin paper as a base material, and the heat-fusible ink layer has an effect of preventing penetration into the base material and an effect of peeling from the base material during printing. When a lubricant is contained in the ink layer, the viscosity of the ink layer when melted increases, preventing penetration into the base material, and its lubricity allows the ink layer to be quickly peeled off (melt transfer). It was completed based on the new knowledge that it is possible to form a clear printed image without chipping or unevenness with less heat energy. Examples of the lubricating agent in the present invention include synthetic lubricating oils such as silicone oil, polyalkylene glycol, fluorine oil, and polyα-olefin, and solid lubricants such as molybdenum disulfide and graphite. As the silicone oil, for example, dimethyl silicone oil (for example, Shin-Etsu Chemical Co., Ltd.)
KF-96), phenylmethyl silicone oil (e.g. Molycote 33, manufactured by Dow Corning)
etc. Examples of the polyalkylene glycol include polyoxypropylene glycol monoether (for example, Newpol LB625 manufactured by Sanyo Chemical Industries, Ltd.), polyoxyalkylene derivatives (for example, Unilube manufactured by Nippon Oil & Fats Co., Ltd.),
MB38). Examples of the fluorine oil include polychlorotrifluoroethylene (for example, Daifloil 10 manufactured by Daikin Industries, Ltd.).
etc. Examples of the poly-α-olefin include α-olefin oligomers (for example, Lipolube # ₄ manufactured by Lion Oil Co., Ltd.). Examples of the molybdenum disulfide include mineral oil paste or synthetic oil-based molybdenum disulfide (eg, Molycote G manufactured by Dow Corning, Molypaste H manufactured by Sumiko Lubricants Co., Ltd.). Further, as the graphite, for example, synthetic oil paste graphite (for example, Nippon Graphite Industries Co., Ltd.)
Piercing oil # ₅ ) manufactured by Hitachi Powder Metallurgy Co., Ltd. and graphite oil (Hitasol GO-102) manufactured by Hitachi Powder Metallurgy Co., Ltd. The amount of such a lubricant is preferably 0.1 to 15 parts (by weight, hereinafter the same), more preferably 0.5 to 5 parts, based on the total amount of the heat-fusible ink layer. If the amount of the lubricant used is less than the above range, there will be no effect of preventing penetration or improving releasability, and if it is more than the above range, the applied ink layer will peel off, both of which are undesirable. Such a lubricant is uniformly dispersed in a hot-fusible ink layer and applied onto the substrate. As for the other ingredients forming the heat-fusible ink layer, the usual ingredients for the heat-fusible ink layer can be used as they are, and there are no particular restrictions on their use. Other ingredients forming the hot-melt ink layer include, for example, colorants, binders, petroleum resins, and softeners. The hot-melt ink layer can be formed by hotmel coating a composition comprising the lubricant, colorant, binder, petroleum resin, and softener, or by dispersing the composition in a suitable solvent. It is formed by coating it with solven. As a binder agent, for example, carnauba wax,
Materials that can be easily melted by heat are preferably used, such as waxes such as auriquy wax and microcrystalline wax, or resins such as low molecular weight polyethylene and polyvinyl stearate. As the softener, materials that can be easily melted by heat, such as polyvinyl acetate, polystyrene, styrene-butadiene copolymers, cellulose esters, cellulose ethers, and acrylic resins, are preferably used. As the colorant, various dyes or pigments that have been widely used in the field of copying paper can be used without any particular restrictions. These binder agents, petroleum resins, softeners, and colorants are used in a total amount of 100 parts (parts by weight,
(same below), 5 to 55 copies, 0.5 to 55 copies, respectively
The blending proportions are preferably 10 parts, 5 to 40 parts, and 2 to 25 parts, in which case the heat-melt ink layer formed has very good melt transferability. In the present invention, a heat-sensitive coloring agent may be used as the coloring agent. The heat-sensitive coloring agent consists of a dye precursor that can develop color by reacting with an acid and an organic or inorganic acid that is solid or semi-solid at room temperature.
A substantially colorless or light-colored heat-melting ink layer is formed by uniformly dispersing or dissolving the heat-sensitive color former binder. The heat-melting ink layer obtained using such a heat-sensitive coloring agent is produced by melting the dispersed solid or semi-solid acid by the heat generated from the heating head, and reacting with the dye precursor to form a clear color. form a recorded image. As the dye precursor, various dye precursors such as phenothiazine type, fluoran type, auramine type, triphenylmethane type, and spiropyran type are all suitably used. As the organic or inorganic acid, for example, benzoic acid, tartaric acid, citric acid, salicylic acid, stearic acid, gallic acid, bisphenol A, naphthoic acid, pyrophosphoric acid, metaphosphoric acid, etc. are preferably used. The heat-fusible ink layer in the present invention has a thickness of 15 μm.
Hereinafter, it is preferably used in a range of 2 to 5 μm. If the thickness is greater than the above range, a large amount of thermal energy will be required to transfer the ink layer, and the resolution will deteriorate, which is not preferable. Next, a case where recording is performed using the thermal transfer recording medium of the present invention using the facsimile apparatus shown in FIG. 3 will be described. That is, FIGS. 1 and 2 are schematic explanatory diagrams showing the recording method of the thermal recording medium of the present invention. In FIGS. 1 and 2, reference numeral 5 denotes a thermal recording medium of the present invention comprising a base material 7 and a heat-melting ink layer 8;
6 is a copy sheet, 2 and 3 are each configured by the pinch roller and printing pattern described above,
A heating head in which heating resistive elements are arranged in a matrix of dot elements such as 1 x 7, 5 x 7, 7 x 9, etc., 9 and 10 are terminals for applying pulses to the heating head 3, and 11 is a terminal on the copy sheet. This is a recorded image formed in In FIG. 1, the thermal recording medium 5 is mounted so that its heat-fusible ink layer 8 faces the copy sheet 6, and the base material 7 of the thermal recording medium 5 is in contact with the heating head 3. On the other hand, copy sheet 6
is in contact with pinch roller 2. Note that the copy sheet 6 is ordinary paper. When pulses corresponding to the printing pattern are applied from the terminals 9 and 10, the heating head 3 generates heat from the dots corresponding to the printing pattern. The Joule heat is instantaneously transmitted to the heat-fusible ink layer 8 through the base material 7, and partially melts the ink layer 8 in accordance with the printed pattern. As shown in FIG. 2, when the pulse application ends, the heating head 3, thermal recording medium 5, and copy sheet 6 are separated from each other, and at that time, the portion of the hot melt ink layer that has been melted according to the printing pattern is A printed image 11 that is peeled off from the base material 7 and transferred to the upper surface of the copy sheet 6, following the printing pattern.
form. In this way, pulse application is repeated and recording is performed continuously. In the present invention, a conventionally known heat-sensitive coloring layer may be provided on the surface of the base material 7 on which the heat-melting ink layer 8 is not provided, so that recording and copying onto the copy sheet 6 can be performed simultaneously. Furthermore, another thermal paper may be interposed between the thermal recording medium 5 of the present invention and the heating head 3. The printed image 11 thus formed is clear because the thin paper that is the base material 7 has excellent heat resistance and thermal conductivity, and the heat-melting ink layer 8 has excellent releasability from the base material 7. The resolution is high,
It has an excellent advantage of not having any unevenness or omission, and also has the advantage of being able to quickly melt and transfer the ink layer 8 with less thermal energy, thereby improving the printing speed.
Moreover, since the hot-melt ink layer 8 contains a lubricant, it does not penetrate into the thin paper that is the base material 7, and therefore, the recording medium of the present invention has no risk of contaminating the heating head 3. Therefore, it can be suitably used as a recording medium for thermal facsimiles and thermal printers. Next, the recording medium of the present invention will be explained with reference to Examples and Comparative Examples. Example 1 0.6 parts of dimethyl silicone oil (KF-96 manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a lubricant to 100 parts of a hot-melt ink composition having the following composition, and the mixture was mixed uniformly. It was applied onto a base material (one-time carbon base paper) to obtain a 4.5μ thick heat-melting ink layer. (Components) (Parts) Carnauba wax 45 Petroleum resin 3 Ethyl cellulose 30 Carbon black 22 Example 2 A heat-fusible ink layer was obtained in the same manner as in Example 1, except that the amount of dimethyl silicone oil added was 4.5 parts. Comparative Example 1 A heat-fusible ink layer was obtained in the same manner as in Example 1 except that dimethyl silicone oil was not added. Comparative Example 2 A heat-fusible ink layer was obtained in the same manner as in Example 1, except that the amount of dimethyl silicone oil added was 20 parts. For each of the thermal transfer recording media thus obtained, the ink permeability to the back surface of the substrate and the releasability of the ink layer were examined. That is, the permeability of the ink was determined by coating the ink on the substrate, leaving it for one day at room temperature, and observing whether or not the ink had leached to the back surface of the substrate. In addition, the releasability of the ink layer is the degree to which ink remains in the printed area when printing is performed on plain paper at a speed of 30 characters/second using a thermal printer (Thermal Printer 100 manufactured by Oki Electric Industry Co., Ltd.), that is, whether the ink is completely removed. The presence or absence of residual ink that adhered to the substrate without being transferred was observed. The results of these tests are shown in the table below.

[Table] When the thermal transfer recording medium obtained in Comparative Example 2 was wound into a roll, peeling was observed between the ink layer and the base material. On the other hand, in Examples 1 and 2, no peeling of the ink layer was observed during winding. In addition, as lubricating agents, Newpol LB625 (polyoxypropylene glycol monoether manufactured by Sanyo Chemical Industries, Ltd.), Dyfloil 10 (Daikin Industries, Ltd.)
Polychlorotrifluoroethylene manufactured by Co., Ltd., Molykoat (mineral oil paste molybdenum disulfide manufactured by Dow Corning), and Piercing Oil #5 (synthetic oil paste graphite manufactured by Nippon Graphite Industries Co., Ltd.) were used in the above examples, respectively. In the same manner as in 1 and 2, the ink permeability and peelability of the ink layer were investigated for the ink contained in the hot-melt ink layer, but no ink permeation or residual ink after printing was observed. No peeling of the ink layer from the base material was observed even when the ink layer was wound into a roll.

[Brief explanation of drawings]

1 and 2 are schematic explanatory diagrams showing the recording method of the thermal transfer recording medium of the present invention, and FIG. 3 is a schematic explanatory diagram showing an example of a normal facsimile machine using thermal paper. (Main symbols in the drawing) 5: Thermal transfer recording medium,
7: Base material, 8: Hot-melt ink layer.

Claims (1)

[Scope of Claims] 1. A heat-melting ink layer provided on a substrate is heated with a heating head from the back side of the substrate, and the heated portions of the ink layer are selectively transferred to a receptor to print. In a thermal transfer recording medium used in a recording method for forming an image, the base material is thin paper, and the heat-fusible ink layer prevents ink from penetrating into the thin paper;
A thermal transfer recording medium containing a lubricant that improves the releasability of the ink layer. 2. The recording medium according to claim 1, wherein the lubricant is silicone oil, fluorine oil, or polyalkylene glycol. 3. The recording medium according to claim 1, wherein the lubricant is a solid lubricant.