JPS5964394A - Thermal recording medium - Google Patents

Abstract

PURPOSE:To obtain a thermal recording medium enabled in the high speed copying of an image having good preservability in excellent sharpness and transferrability in printing due to a thermal head, by specifying the smoothness of a paper substrate and the heat conductivity and the viscosity of a heat meltable ink layer. CONSTITUTION:The heat conductivity of a heat meltable ink layer 3 is adjusted to 4X10<-4>-15X10<-4>cal/cm.sec. deg.C, the viscosity thereof at 100 deg.C due to a Brookfield viscometer to 20-200 cp and the surface Beckmann smoothness of a paper substrate 1 to be provided with the above mentioned ink layer to 60-20,000sec to obtain an objective recording medium 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal recording medium for thermal transfer recording onto plain paper or the like using a heated printing body such as a thermal head.

In this Yuzu thermal recording medium, when the heat-melting ink layer is thermally transferred to plain paper, smearing occurs due to the binder agent, resulting in poor clarity, poor transferability, and a portion of the print being transferred. There were drawbacks such as chipping and missing parts.

Various improvements have been made to overcome these drawbacks, but at present no satisfactory results have been achieved.

The present invention was developed as a result of intensive research in view of the above circumstances.
We learned that the clarity and transferability of these prints are greatly influenced by the smoothness of the base material and the thermal conductivity and viscosity of the hot-melt ink layer.As a result of further research based on this knowledge, we have developed We have achieved a thermal recording medium with excellent clarity and transferability when printing with the thermal head used.

That is, in the present invention, the Bekk smoothness of the surface of the filter paper base material provided with the heat-fusible ink layer is 60 to 2 tap seconds, and the thermal conductivity of the heat-fusible ink layer is 4X10-' to 15.
X 10-'aal/am ・sea -9:j, and the viscosity measured by a B-type viscometer at 100°C is 20-2
00aP is provided.

In the present invention, with the above configuration, when thermal transfer is performed by applying a thermal head to the opposite side of the paper substrate provided with the heat-fusible ink layer, the heat-fusible ink layer is not completely melted, but only partially melted. It is transferred to plain paper in a molten or softened state, and the transferred printed image does not bleed, chip, or drop out, and is extremely clear.

The relationship between the above structure and the effects of the present invention is as follows.

If the smoothness of the paper base material is lower than the above range, even if the heat melt ink layer satisfies the above requirements, the adhesion between the heat melt ink layer and the paper base material will be poor due to poor smoothness. Thermal conductivity from the paper base material to the ink layer was poor, resulting in uneven transfer.

From this point of view, the higher the smoothness of the paper base material, the better the transferability, but if it is too smooth, the ink layer tends to peel off from the paper base material during printing or storage. In this case, it is effective to add a softener having adhesive properties to the ink layer, which will be described later.

In addition, when the thermal conductivity of the heat-fusible ink layer is lower than the above range, heating for one printing is instantaneous when printing with a thermal head, so the entire ink layer in the printing area is heated. Transmitting energy is the field [
This results in a disadvantage of poor transferability. On the other hand, if the thermal conductivity is too high, a wide area around the printed area will also be melted and softened, resulting in poor print clarity.

Further, when the viscosity of the hot-melt ink layer is lower than the above range, 4J printing bleeds, while when it is higher than the 011 range, the transferability is poor.

In summary, the smoothness of the paper base material, the heat-melting ink) + y
When both the thermal conductivity and viscosity of J satisfy the above values, thermal transfer printing with good clarity and transferability is possible.

Next, the present invention will be explained based on the drawings.

FIG. 1 is a schematic enlarged partial sectional view showing a preferred embodiment of the thermal recording medium of the present invention, and FIGS. 2 and 6 show the states of the thermal recording medium of the present invention and a copy sheet during and after printing, respectively. It is a schematic explanatory diagram.

The thermal recording medium shown in FIG. 1 has a paper base material (1) provided with a thermosensitive coloring layer (2) on one side and a thermofusible ink layer (3) on the other side.

The paper base material (1) has Bekk smoothness on one side (J Engineering 5P811
9) is 60-20000 seconds, <200-160
00 seconds. The paper base material (1) is selected from among papers such as glassine paper, thin paper, electrically insulating paper, parchment paper, and wax paper materials that satisfy the above-mentioned smoothness. These papers also have a thickness of 20 to 60μ, a thickness of <60 to 50μ, and a density of 0.75 to 1.6y/
Cm3, Nakazu < 0. '8~1.2. /crn” is preferable.

The hot-melt ink layer (3) is formed by hot-melt coating with a hot-melt ink composition, or by applying a coating solution prepared by dispersing the composition in an appropriate solvent to the paper substrate (1). The thickness of the smooth surface is 1
~15 p/m'', preferably 3 to 10 p/m.

The ink layer (8) consists of a binder, a softener, and a colorant, and these components are made up of 100 parts of the total amount of the ink layer (overlapping part,
It is preferable to set the blending ratio to be 5 to 85 parts, 5 to 65 parts, and 5 to 25 parts, respectively. Further, 2 to 30 parts of a powdered thermally conductive substance is added to 100 parts of the total amount of the ink layer to increase the thermal conductivity of the ink layer to 100 parts by 100 parts.
15 X 10-'cal/cm-sec-'O.

Nakazu < 5 X 10"" ~ 9 X 10-'ca
Dispersion mixing is performed to obtain l/Cm·sec·00.

The binder agent has a penetration degree of 10 to 60 (25
It is preferable to use a solid wax with a temperature of
Waxes such as beeswax, ceresin wax, and spermaceti wax are used, and if necessary, substances that can be more easily melted by heat than the above-mentioned waxes are used in combination, such as low molecular weight polyethylene, oxidized wax, and ester wax. The viscosity of the ink layer (3) is adjusted to be 20 to 2000 F as measured by a B-type viscometer at 100°C.

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, or lubricating oils are preferably used. Ru.

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.

Examples of the powdery thermally conductive substance include acetylene black, lamp black, graphite, aniline black,
The thermal conductivity of black pigments such as Ketjen Black (product name) is 6. OX10=~25. OX 10-'ca
l/eec-cm・00(7) thing, Oyo? J7/
Materials with good thermal conductivity, such as l/l/minilum, tin, or metal powder such as zinc, are preferably used.

In this way, the heat-fusible ink layer (3) is prepared by adjusting the proportions of the binder agent, softener, coloring agent, and powdered thermally conductive substance so that the viscosity and thermal conductivity of the ink layer (3) are within the above range. It was designed so that

A heat-sensitive coloring layer (2) is provided on the opposite side of the base material (1) from the ink layer (3), and the heat-sensitive color forming layer (2) is provided on the side opposite to the ink layer (3). Color printing is performed on the color forming layer (2).

≠# The thermosensitive coloring layer (2) is made by uniformly dispersing a dye precursor capable of developing color by reacting with an acid and an organic or inorganic acid that is solid or semi-solid at room temperature using an appropriate binder agent. It is a layer with a thickness of about 10 μm or less that is fixed as an integral layer. This heat-sensitive coloring layer (2) is formed by melting the dispersed solid or semi-solid acid by Joule heat generated from the thermal head, and forming a coloring reaction with the dye precursor b [f] to form a clear printed image. do.

As the dye precursor, various dye precursors such as phenothiazine dye precursor, fluoran dye precursor, auramine dye precursor, triphenylmethane dye precursor, and spiropyran thread are preferably used.

As the organic or inorganic acid, for example, benzoic acid, tartaric acid, citric acid, salicylic acid, stearic acid, gallic acid, bisphenol A1 naphthoic acid, pyrophosphoric acid, metaphosphoric acid, etc. are preferably used.

The thermal recording medium of the present invention has a heat-melting ink layer (3) on the surface opposite to the coloring surface of commercially available thermal paper.
It may be manufactured by providing.

In the present invention, the penetration prevention layer (2) and the base material (1) are manufactured using a base material pre-impregnated with a coating solution for forming a shadow on the penetration prevention layer made of waxes or synthetic resins, or the heat-sensitive coloring layer (2) and the base material (1
) If necessary, a similar permeation prevention layer may be provided between the two.

Next, the above-mentioned group vJ (1), thermosensitive coloring layer (2)
The case where two copies are made by a thermal printer using the thermal recording body of the present invention comprising a heat-melting ink layer (3) will be explained.

That is, the second part shows the state of the thermal recording medium of the present invention and the copy sheet during printing, and (4) shows the state of the base material (
1), thermosensitive coloring layer (2) and thermofusible ink layer (3)
Thermal recording medium of the present invention consisting of (5) is a copy sheet;
(6) is a platen, (γ) is a dot element matrix of 1 x 7.5 x 7.7 x 9 etc. depending on the configuration of the printing pattern) Thermal head with heat generating resistor elements arranged in an IJ box shape, (8)
) and (9) are terminals for applying pulses to the thermal head (7), and α0) is a printed image that is being formed.

The thermal recording medium (4) is mounted so that its thermal melting transfer layer (3) faces the copy sheet (5), and the thermal coloring layer (2) of the thermal recording medium (4) is attached to the copy sheet (5). It is in contact with the head (7), while the cobby sheet (5) is in contact with the platen (6). Note that the copy sheet (5) is ordinary paper. When pulses corresponding to the printing pattern are applied from terminals (8) and (9), the thermal head (γ
), dots according to the printing pattern generate Joule heat. The Joule heat is transmitted to the heat-sensitive coloring layer (2), melts the solid or semi-solid organic or inorganic acid dispersed in the heat-sensitive coloring layer (2), and colors the dye precursor to form a printed pattern. While forming a printed image (10) according to the printed pattern, the ink is instantaneously transmitted to the hot-melt ink layer (3) through the base material (1), and the ink layer (3) is partially printed according to the printed pattern. hJ Shizu-4ru.

FIG. 6 shows the state 714 after pulse application, (1)
The symbols from to (9) are the same as those in FIG. 2, (11) is a completely formed printed image, and (12)
) is a copy image (a printed image formed on the copy sheet (5), hereinafter the same).

When the pulse application ends, the thermal head (7), the thermal recording medium (4) and the copy sheet (5) are separated from each other for a minute.
Then the printing pattern becomes 11t'
,, the f6-fused hot bath melting ink I/+y portion is peeled off from the base material (1) and transferred to the upper surface of the copy sheet (5), forming a copy image (I2) according to the printed pattern. .

On the other hand, in the thermosensitive coloring layer (2), the coloring reaction between the dye precursor and the organic or inorganic acid has been completed, thereby forming a clear printed image (11).

In this way, pulse application is repeated and copying is performed continuously. In addition, although FIGS. 2 and 6-1 show the cotton used when copying is performed by placing the thermal recording medium (4) of the present invention on the copy sheet (5) at +W2, the copy sheet (5) If the thermal recording medium has good thermal conductivity, it is of course possible to use it by placing a copy sheet on the thermal recording medium.

The printed color thus formed! (11) is very clear and easily readable.

Further, the formed copy image (12) is made of a heat-fusible ingi layer (3) by f1911 of a thermally conductive material as described above.
The melting transferability of the ink has been changed, and the ink in 11 is melted,! ll! Good transfer f'l 1~
Since it is a thin layer of 15,/m, it is possible to easily form the limited image (12) on the copy sheet (5), and since the amount of the transferred image is an appropriate amount, a clear copy image ("' ) can be changed and moreover, the compound Lj, only (+2) obtained by transferring a hard ink such as a hot-melt ink has the advantage of being highly fast and cannot be easily tampered with. This is extremely convenient if you need to store it.

Furthermore, when using the thermal recording medium of the present invention, usually 6/1
Thermal pulse shift of about 0005ea (16wt/mm2)
('i4 A clear print appearance and copy image can be formed.

Therefore, the thermal recording medium of the present invention has a high copying speed of approximately 60 characters per second, approximately twice the speed of copying by laying two sheets of conventional thermal paper (11), and has excellent bath-fusion transfer speed. Due to its characteristics, it is possible to copy clear printed images extremely easily, making it extremely useful for beginners using thermal printers that require speed.

4 Drawings 1'j5. ;+: "Explanation: 1 implementation of the recording medium for 1 ton 1 6 light
, +j, :Show - Figure 2 and Figure 31 show the state of the thermal recording medium and copy sheet of the present invention during and after printing, respectively.
This is an explanatory diagram of the construction.

(Main drawing No. 70) (1) Second no. 1 benefit (2): +L is (coloring layer (3): Heat 7 fusion tel ink hapa) (1): Me, J effect: 11 fishing, medium First decoy.

1

Claims (1)

[Claims] 1 The surface of the filter paper base material provided with a heat-fusible ink layer is smooth and smooth 1 (° is 6D to 20,000 seconds, and the thermal conductivity of the heat-fusible ink is 4×10 to 15×1 [1ca
J/am-sθCl0C and B at 100°0
A thermal recording medium having a viscosity of 20 to 2000 P as measured by a type viscometer.