JPS6161891A - Thermal recording medium - Google Patents

Abstract

PURPOSE:To enable clear two-color recording to be conducted on an ordinary paper, by providing the first ink layer capable of forming a color and being transferred at a predetermined heating temperature, and the second ink layer capable of being transferred at a heating temperature lower than said predetermined heating temperature. CONSTITUTION:The thermal recording medium 1 comprises a support layer 2 on which the first ink layer 3 capable of being transferred at a higher temperature and the second ink layer 4 capable of being transferred at a lower temperature are laminated. The first ink layer 3 comprises a dye precursor 5 and a color developer 6. The recording medium 1 has its ink side brought into contact with a transfer paper 7, and is heated by heating elements 9 of a thermal head 8 from the side of the support layer 2. When the heat applied by the elements 9 is at such a lower temperature as to melt only the second ink layer 4 (which is colored, for example, in red) a red image is formed on the paper 7. When the heat is at such a higher temperature as to melt the first ink layer 3 and cause the reaction of the dye precursor with the color developer (which are so selected as to form, for example, a black color), a black image is formed on the transfer paper 7.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a heat-sensitive recording medium used to perform two-color recording using heat, and more specifically, the present invention relates to a heat-sensitive recording medium that is used to perform two-color recording using heat. The present invention relates to a heat-sensitive recording medium capable of transferring 2+m colors onto a recording member.

(Prior art) In thermal transfer recording, an ink ribbon, which is a heat-sensitive recording medium coated with heat-melting ink, is placed on top of a transfer paper, and a thermal signal is applied from a thermal head to melt and transfer the ink onto the transfer paper. is being recorded. In this recording method, plain paper can be used as the transfer paper, and the thermal recording medium capable of two-color recording is a thermal recording medium in which two thermal transfer ink layers with different melting temperatures and hues are laminated on a base. medium is proposed. Depending on the heating temperature, this recording medium can transfer only one layer or both layers.

Further, as another heat-sensitive recording medium capable of two-color recording, a heat transfer medium containing a heat-sensitive coloring material has been proposed. This thermal recording medium contains a thermal coloring material in the thermal transfer ink that develops a color different from that of the thermal transfer ink, and the transfer ink surface of this thermal recording medium is overlapped with plain paper, and from the base side of the thermal recording medium, the thermal head The ink in the selectively heated portion is transferred onto transfer paper for recording. At this time, when heating at a relatively low temperature, only transfer of the transfer ink occurs, and when heating at a relatively high temperature, at the same time as the ink is transferred, the heat-sensitive coloring material contained in the ink is transferred to the transfer ink. The color develops to a different hue. This allows two-color recording by changing the heating temperature.

(Problems to be Solved by the Invention) However, when using such a recording medium, for example, when only red ink transfer occurs at low temperatures, and black ink transfer or transfer and black coloring occur at high temperatures, However, when a black image is formed, red ink is transferred to the periphery of the image, or although it is transferred, no color is developed and a clear image cannot be obtained.

The object of the present invention is to eliminate such conventional problems and provide a heat-sensitive recording medium that can perform clear two-color recording on plain paper.

(Means for Solving the Problems) A thermosensitive recording medium according to the present invention includes a support layer whose one surface is a heated surface, and a support layer laminated on the other surface of the support layer, which is heated at a predetermined heating temperature. a first ink layer capable of color development and transfer;
The image forming apparatus is characterized by comprising a second ink layer layered on the first ink layer and capable of being transferred at a heating temperature lower than the predetermined heating temperature.

Hereinafter, the present invention will be described in detail based on the drawings.

FIG. 1 shows the basic structure of the two-color thermal recording medium of the present invention. Thermal recording medium 1 has a first transfer ink layer 3 transferred onto a support layer 2 at a relatively high temperature and a second transfer ink layer 3 transferred at a relatively low temperature.
The transfer ink layers 4 are laminated in this order.

The support layer 2 has appropriate heat resistance strength and thermal conductivity of an appropriate value (usually 3.
sec・c+n・℃ or less), there are no special restrictions on the material. For example, paper such as condenser paper or glassine paper, or plastic film such as polyester film or polycarbonate film can be used. Since the thermal recording medium is heated from the support layer side by a thermal head or the like, it is better to minimize the loss of thermal energy in the support layer, and the thickness of the support layer is usually preferably 60 μm or less. The first transfer ink layer 3 is made of a binder such as carnauba wax, ester wax, polyester, beeswax, ceresin wax, etc., and polystyrene, styrene, butyral resin, polyvinyl acetate, Bukgen copolymer, cellulose-esters, cellulose-ether. , azolyl resins, petroleum resins, stearic acid, lanolin,
This layer is made of a softener such as vaseline, and is made by mixing these in an appropriate ratio. Further, the first transfer ink layer 3 contains a dye precursor 5 and a color developer 6.

These dye precursors and color developer react during transfer at a relatively high temperature to develop color. In order to obtain a black or blue color upon color development, dye precursors such as 3-diethylamino-6-methyl-7-anilinofluorane, crystal violet lactone, 3°7-bisdiethylaminofluorane, 4. 4'-bisdiethylmethylaminobiperazine hydrol or the like may be used. In addition, as a color developer, depending on the dye precursor used, 4,4-impropylidenediphenol, 2,2-bis(4-hydroxyphenyl)n-hebutane, 1,1-bis(4- Hydroxyphenyl) cyclohexane, benzoic acid, salicylic acid, stearic acid, etc. may be used. These dye precursors and color developers are microencapsulated as necessary. In this case, it is desirable to use a material for the microcapsules that dissolves at a temperature that is approximately the same as or higher than the temperature at which the first transfer ink layer 3 dissolves.

The second transfer ink layer 4 is formed on the first transfer ink layer 3. As the material for the second transfer ink layer, the same material as the first transfer ink layer 3 can be used, but the second transfer ink layer 4 can be transferred at a lower temperature than the first transfer ink layer 3. Consists of materials and composition. For example, if the second transfer ink layer 4 is to have a red hue, lake red, rhodamine base, red red color, or the like may be used.

Other additives may be added to the first and second transfer ink layers as necessary. For example, to improve thermal conductivity, it is effective to add fine powder of metal such as aluminum, copper, tin, or zinc. The first and second transfer ink layers are each formed by hot melt coating or by solvent coating a coating liquid in which a transfer ink composition is dispersed in a solvent. Further, the coating amount of each of these transfer ink layers is preferably 3 to 20 g/m''.

(Function) Next, with reference to FIG. 2, the transfer function of the heat-sensitive recording medium according to the present invention configured as described above will be explained.

FIG. 2 shows a basic principle diagram of a transfer section for performing two-color recording. The recording medium 1 is conveyed in the direction of arrow a by a conveying means (not shown), and is superimposed on the transfer section. In this state, the transfer ink side of the recording medium 1 is in contact with the transfer paper 7, and the recording medium 1 is selectively heated by the heating element 9 of the paper head 8 from the support layer 2 side. Thereafter, the transfer paper 7 and the recording medium 1 are conveyed in the directions of arrows c and b, respectively, and are separated from each other. At this time, if the heat applied by the heating element 9 is relatively low enough to dissolve only the red-colored second transfer ink layer 4, a red image will be formed on the medium and square paper 7. be done. Further, the heat applied by the heating element 9 is relatively high enough to dissolve the first transfer ink layer 3 and cause a reaction between the dye precursor and the color developer contained therein, so that the hue of the color is developed. For example, if the image is black, a black image is formed on the transfer paper 7.

(Effects of the Invention) In the thermal recording medium according to the present invention, since the first transfer ink layer develops color only at a relatively high temperature, only the second transfer ink layer can be transferred at a relatively low temperature lower than the coloring temperature. When transferring, even if some of the first transfer ink layer is transferred, since the first transfer ink layer does not develop color, the color of the transferred second ink layer will not be contaminated. In addition, when transferring and coloring the first transfer ink layer, the transferred area and the area where one color is generated are approximately the same size, so that the color formed by the transfer of the first transfer ink layer is An unnecessary image having the color of the second transfer ink layer is rarely formed around the image, and a clear image can be obtained.

(Example) Dispersion A in which the following ASBs were dispersed using a ball mill,
A solution prepared by mixing 5 parts of
A first color transfer ink layer was obtained by coating and drying at a coating amount of . A second transfer ink layer having composition C was provided thereon to form a heat-sensitive recording medium.

A. Fluorane-based leuco paint 20 parts by weight Rosin-modified filler resin 10 parts by weight Mineral spirit 90 parts by weight B. 4,4'-isopropylidene diphenyl 20 parts by weight Stearic acid bisamide 10 parts by weight Microcrystal wax
5 parts by weight paraffin wax
5 parts by weight Rosin modified phenolic resin 10 parts by weight Mineral spirit 240 parts by weight C0 paraffin wax 45 parts ffi! Carnauba wax 35 parts by weight Vaseline
5 parts by weight Dye (Lake Red) 20 parts by weight The ink surface of the above heat-sensitive recording medium and the transfer paper were overlapped and heated selectively from the support layer side of the heat-sensitive recording medium using a heating head. At this time, when the heating conditions were changed, a red color was recorded under a relatively low temperature condition, and a black color was recorded under a relatively high temperature condition. In both cases, clear images with no bleeding or the like were formed.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a thermal recording medium of the present invention, and FIG. 2 is a basic principle diagram showing a thermal transfer section. 1 thermal recording medium, 2 support layer, 3 first transfer ink layer, 4 second transfer ink layer. Patent applicant: Fuji Xerox Co., Ltd. Figure 1 Figure 2
Support layer 7--Transfer resistor 3-First transfer ink layer 8-11 Thermal head 4-Transfer ink layer of $2
9-11 Heating element 5-Kumeshina front drive stop

Claims (1)

[Claims] a support layer; a first ink layer laminated on the surface of the support layer and capable of color development and transfer at a predetermined heating temperature;
a second ink layer that is laminated on the surface of the ink layer and is transferable at a heating temperature lower than the predetermined heating temperature.