JPS63280685A - Thermal transfer material - Google Patents

Abstract

PURPOSE:To enable bichromatic recording in a simple way by building a first ink layer, an intermediate layer and a second ink layer sequentially on a support to form a thermal transfer material and regulating the adhesive power between each layer in a specific relation. CONSTITUTION:A first ink layer, an intermediate layer 3 and a second ink layer 2 are sequentially laminated on a support 10 to form a thermal transfer material. In this case, the chromatic tones of the first ink layer and the second ink layer are different. Then the adhesive power F1 between the support 10 and the first ink layer 1 and that F2 between the first ink layer and the second ink layer 2 are set to F1<F2, when a contact pressure when thermal energy is supplied to a thermal transfer ink layer 12 (the first ink layer, intermediate layer and second ink layer) is relatively large, while the adhesive power is set to F1>F2, when the contact pressure is relatively small.

Description

DETAILED DESCRIPTION OF THE INVENTION Crossover I The present invention relates to a thermal transfer material for transferring recorded images of two different tones onto a recording medium.

The thermal transfer recording method has the general characteristics of thermal recording methods, such as the equipment used is lightweight, compact, noiseless, and easy to operate and maintain, as well as eliminating the need for colored processed paper. In addition, it is characterized by excellent durability of recorded images, and has been widely used recently.

This thermal transfer recording method generally uses a thermal transfer material made by coating a sheet-like support with a thermal transfer ink made of a heat-melting binder and a colorant dispersed therein. By superimposing the thermally transferable ink layer on the recording medium so that it is in contact with the recording medium, and applying heat from the support side of the thermal transfer material using a thermal head or the like, the molten ink layer is transferred to the recording medium. A transferred recorded image is formed on a recording medium according to the shape of heat supply.

Furthermore, there is a strong market demand for two-color printing while taking advantage of the advantages of the thermal transfer recording method, and various techniques for obtaining two-color printing have been proposed.

Conventionally, as a method for printing in two colors on plain paper using a thermal transfer recording method, Japanese Patent Application Laid-open No. 148591/1983 describes
Two heat-melting high melting point ink layers A and a low melting point ink layer B containing different colorants are sequentially laminated on the base material from the base material side, and in the case of low heat application energy, the low melting point ink layer A two-color thermal transfer recording element is disclosed in which only ink layer B is transferred onto plain paper, and when high thermal energy is applied, both heat-melting ink layers A and B are transferred to obtain a two-color record.

Furthermore, Japanese Patent Application Laid-Open No. 59-64389 discloses a two-color effect in which an ink layer is provided on a base material, consisting of an ink that melts and leaches when heated, and an ink that melts and peels off at a temperature higher than the melting and leaching temperature. A thermal transfer ink sheet is disclosed.

In these methods, two-color printing is performed by changing the temperature of the ink layer by changing the energy applied to the thermal head in two stages. However, if high energy is applied to raise the temperature of the ink layer,
Due to the diffusion of heat, a relatively low-temperature area is created around the high-temperature area, and as a result, some of the colors printed at a low temperature appear around the area printed at a high temperature. Furthermore, when high energy is applied to the thermal head, it takes a relatively long time for the temperature to drop, which has the disadvantage that colors printed at low temperatures tend to trail behind areas printed at high temperatures. be.

In addition, in any of the conventional two-color recording methods described above, there is a constraint that a material with a relatively low melting point must be used as the ink material for printing at low temperatures, which causes background stains on the recording medium and thermal transfer. Various problems have arisen, such as a decline in the shelf life of the material.

11.11 The main object of the present invention is to eliminate the above-mentioned drawbacks and to provide a heat-sensitive transfer material capable of beautiful recording in two colors using a simple method.

^W As a result of intensive research, the inventors have found that the magnitude relationship between the adhesive force caused by the intermediate layer provided between two ink layers and the adhesive force between the support and the ink layer is determined by the application of thermal energy when supplying thermal energy. We have found that it is possible to reverse this by changing the pressure.

The thermal transfer material of the present invention is based on the above-mentioned knowledge, and more specifically, on a support, from the support side, at least a first ink layer, an intermediate layer, and a second ink layer having a different color tone from the first ink layer. a thermally transferable ink layer consisting of an ink layer, and an adhesive force between the support and the first ink layer (F1
), and the adhesive force between the first ink layer and the second ink layer (F
2) is F<F2 when the contact pressure when supplying thermal energy to the thermal transferable ink layer is relatively large;
It is characterized in that Fl>F2 when the contact pressure is relatively small.

In other words, the present invention does not rely solely on the melting characteristics of each ink layer (i.e., the presence or absence of melting) based on changes in the amount of thermal energy supplied, as is the case when conventional two-color thermal transfer materials are used. A two-color recorded image is obtained by controlling the adhesive force between each ink layer by pressure when thermal energy is supplied.

Therefore, according to the present invention, tailing or edging due to heat diffusion or cooling after high energy application (as in conventional methods) is eliminated, resulting in a beautiful 2
A colored transferred recorded image can be obtained.

Furthermore, according to a preferred embodiment of the present invention, at the temperature at which the thermally transferable ink layer starts adhesion to the recording medium, Fl
<Contact pressure corresponding to Fi, and F.

> The contact pressure corresponding to F2 is both 3 to 15K.
A thermal transfer material in the range of g/cm' is provided.

According to such a preferred embodiment, the clarity of the two-color recorded image can be further improved.

Hereinafter, the present invention will be described in further detail with reference to the drawings as necessary. “%” indicates quantitative ratio in the following descriptions.
"and 1 part" are based on weight unless otherwise specified.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a schematic sectional view in the thickness direction showing the basic structure of the thermal transfer material of the present invention. Referring to FIG. 1, a thermal transfer material 100 of the present invention includes a first ink layer 1 on a support 10;
It has a thermally transferable ink layer 12 formed by sequentially providing an intermediate layer 3 and a second inter layer 2.

Thermal transfer material 1 of the present invention (in ?O, adhesive strength CF+ between the first ink layer and the support) and the second ink layer and the first
The magnitude relationship between the adhesive force (F, ) between the ink layers is determined by the contact pressure (sensitivity It is necessary that the pressure applied per unit area of the thermal transfer material can be reversed depending on the magnitude of the pressure applied per unit area of the thermal transfer material.

More specifically, in the thermal transfer material 100 of the present invention, when the contact pressure caused by the heating element etc. during the supply of thermal energy is relatively small, the relationship Fl>F2 is established, and the first ink III and the second ink layer 2, and when the contact pressure is relatively large, the relationship Fr < F 2 holds,
The first ink layer 1 and the support 10 are separated.

One aspect of such changes in adhesive strength between each layer will be explained using FIG. 2. In addition, in evaluating the magnitude relationship between the adhesive force (F1) between the first ink layer and the support and the adhesive force (F2) between the first ink layer and the second ink layer in the present invention, each ink layer is Support when transferring to recording medium - 1st
Only the relative ease of separation between the ink layers and the separation between the first and second ink layers shall be considered. That is, when transfer recording is performed on a recording medium using the thermal transfer material of the present invention, if substantially the second ink layer is transferred, Fl>F2, and substantially the first and second ink layers are transferred. When two ink layers are transferred, it is assumed that F, <F2, and the form of peeling of the ink layer when each ink layer is peeled off from the heat-sensitive transfer material and transferred to the recording medium (for example, the form of peeling) (Whether the position is at the exact boundary between the second ink layer or the first ink layer, how much of the intermediate layer remains on the heat-sensitive transfer material after transfer, etc.) shall not be considered in the evaluation of adhesive strength. do.

Figure 2 shows one aspect of changes in the adhesive force between the support and the first ink layer (Fl) and the adhesive force between the first ink layer and the second ink layer (F2) due to pressure during heating. It is. Referring to FIG. 2, at a relatively small pressure P1, Fl>F2, and the first ink layer 1 and the second ink layer 2 are separated, and at a relatively large pressure P2, F1 , <F2, and the first ink layer 1 and the support 10 are separated, so by changing the pressure in this way, the transferred image consisting of the second ink layer, or the first ink layer and the second ink layer is separated. A transferred image consisting of both ink layers is obtained.

In addition, in Fig. 2, the pressure ratio of contact pressure (F2/P+
) is preferably in the range of 1.5 to 8, more preferably 1.5 to 5. If (F2/PI) is smaller than 1.5, it will be difficult to stably separate the two layers. On the other hand, (F
2/P+) is larger than 8, the quality of the recorded image when only the second ink layer is transferred is different from the quality of the recorded image when both the first ink layer and the second ink layer are transferred. Differences are more likely to occur.

Next, an example of the mechanism by which the above functions are expressed will be explained in more detail with reference to FIGS. 3 and 4.

3 and 4 show the thermal transfer material 1 having the structure shown in FIG. 1.
00, and the heating element 4a of the thermal head 4 is attached to the thermal transfer material.
FIG. 2 is a schematic cross-sectional view in the thickness direction of a thermal transfer material showing a case in which thermal energy is supplied from the substrate.

Referring to FIG. 3, when thermal energy is applied from thermal head 4 to thermal transfer material 100, intermediate layer 3 is thermally melted and the cohesive force within intermediate layer N3 is reduced. However, when the pressing force applied by the thermal head 4 to the thermal transfer material 100 is small (for example, the pressure p+ in FIG. 2), the intermediate layer 3 resists the pressing force and maintains its layered state. Therefore, when the thermal transfer material 100 and the recording medium 5 are peeled off immediately after applying thermal energy, the first ink layer and the second ink layer are separated due to cohesive failure in the intermediate layer 3. (Fl>F2)
, a transferred image 2a by the second ink layer 2 is formed on the recording medium 5. At this time, a transferred image can also be obtained by cohesive failure within the second ink layer 2, but in such a case,
The amount of ink transferred from the second ink layer to the recording medium 5 is difficult to be constant, making it difficult to obtain a clear recorded image. For this reason,
The second ink layer 2 when such thermal energy is supplied
The melt viscosity of the intermediate layer 3 is preferably higher than that of the intermediate layer 3.

On the other hand, referring to FIG. 4, when the pressing force is large (for example, pressure P2 in FIG. 2), the intermediate layer 3 cannot maintain its layer state when thermal energy is applied under the pressure. , the first ink [1 and the second ink layer 2 are in contact with each other,
The adhesive force (F2) between the first ink layer and the second ink layer is
Since the adhesive force (Fl) between the first ink layer and the support is greater (Fl<Fz), when the thermal transfer material ioo and the recording medium 5 are separated, the first ink layer and the support are separated. As a result, a recorded image 12a is formed in which both the first ink layer and the second ink layer are transferred.

In the embodiment described above, the contact between the first ink layer 1 and the second ink FJ2 increases the adhesive force between these ink layers. Alternatively, it is preferable that both ink layers contain (at least one component) of a heat-melting binder having a similar composition.In such a preferred embodiment of the present invention, it is possible to reduce the melting point difference between 2ff! class inks by only changing thermal energy. This is contrary to the desirable characteristics of conventional thermal transfer materials, which obtain a two-color recorded image (using the above).

In the thermal transfer material 100 of the present invention as described above, by changing the color tone of the first ink layer 1 and the second ink layer 2, two-color recording using the thermal transfer material of the present invention becomes possible. If you want to obtain the same color tone as that of the first ink layer 1 and the second ink IIJ2, the first ink layer 1 should be colored with a dark color such as black, and the second ink layer 2 should be colored with a dark color such as red (than the first ink layer). ) It is preferable to place brightly colored ones. Also, the first
By setting the ink layer and the second ink layer to similar colors, it is possible to record in two colors, dark and light.

Furthermore, by making the first ink layer a layer containing a white pigment or the like having a large concealing effect, the first ink layer may be used as a correction ink layer.

Next, one embodiment of a recording method for obtaining a two-color recorded image using the thermal transfer material of the present invention will be described.

As described above, the thermal transfer material 100 of the present invention can provide a two-color recorded image by, for example, a relative change in the contact pressure on the support. Therefore, two-color recording becomes possible by adjusting the pressing force (on the platen that supports the recording medium via the recording medium) using, for example, spring pressure. The structure and operation of the thermal head supporting section will be described with reference to FIG. 5, which is a schematic side view showing an example of the mechanism of the thermal head supporting section when the spring pressure is changed in this manner.

Referring to FIG. 5(a), a head holder 22 holding a thermal head 21 is arranged to be rotatable in forward and reverse directions (directions of arrows A and B) about a shaft 22a, and based on the rotational movement, A desired pressure can be applied between the thermal head 21 and the platen 23 to a thermal transfer material or recording medium (both not shown) that is disposed so as to be movable in the extending direction of the head holder shaft 22a. A return spring 24 is provided on the surface of the head holder 22 opposite to the surface facing the platen 23.
It is connected to the head holder 22 so as to be able to apply tension in the direction of arrow A.

On the other hand, on the side of the head holder 22 connected to the return spring 24, a press spring 25 having a U-shape as a whole is arranged so as to be able to apply pressure in the direction of arrow B to the head holder 22. A shaft 26 is provided on the back side in the thickness direction of the pressure spring 25 (upstream or downstream side in the running direction of the thermal transfer material).
A lever 26 that can be rotated in forward and reverse directions around a is arranged, and stoppers 27a and 27b fixedly arranged on this lever 26 cause a U-shaped pressure spring 25 to be rotated.
is in a pinched state.

Furthermore, a roller 28 is arranged on the lever 26 at a position farther from the shaft 26a than the stopper 2a, and a cam 29 is arranged so as to be rotatable in the direction of arrow C while contacting the roller 28. has been done.

Referring to FIG. 5(a), the head holder 22 holding the thermal head 21 is moved up and down (in the direction of arrow A or arrow B) by the action of a cam 29 that rotates with power from a motor (not shown). Moving. As shown in FIG. 5(a), when a cam 29 whose radius changes in three stages by rotation is used, normally the roller 28 at the tip of the lever 26 in contact with the cam 29 is in the fifth position. Cam 2 as shown in figure (a)
It is located in the first row of 9.

In this case, the pressing spring 25 that applies pressing force to the head holder 22 is connected to a stopper 27a provided on the lever 26.
and 27b, and the head holder 2
2 is separated from the platen 23 due to the force from the return spring 24.

Referring to FIG. 5(b), when selectively transferring the second ink layer of the thermal transfer material to the recording medium (when applying a relatively small pressure), the image shown in FIG. 5(b) is The cam 29 rotates in the direction of arrow C, and the roller 28 is positioned at the second stage of the cam.
touches. As a result, the lever 26 moves toward the platen 23 around the shaft 26a, and the pressing spring 25 presses the head holder 22 toward the platen 23. This allows the head holder 22 to further move the platen 2 around the shaft 22a.
3 side (in the direction of arrow B), the thermal head 21 is pressed against the platen 23 (with a relatively small pressure).

When the thermal pad 21 generates heat and prints in the state shown in FIG. 5(b), based on a relatively small pressure,
The second ink layer of the thermal transfer material is selectively transferred to the recording medium, forming a transferred recorded image (not shown) having the color tone of the second ink layer.

On the other hand, when the motor (not shown) connected to the cam 29 receives a signal from the device body (not shown) to change the print color, the cam 29 moves further with the arrow as shown in FIG. 5(c). The roller 28 rotates in the C direction, and the roller 28 comes into contact with the third stage position of the cam 29. As a result, the pressing spring 25 presses the thermal head 21 even more strongly against the platen 23 via the head holder 22.

When the thermal head 21 generates heat in this state, based on the relatively large pressure, the first and second thermal transfer materials are
Both ink layers are transferred to the recording medium, forming a transferred recorded image (not shown) having the same tone as the first ink layer or a mixture of the first ink and the second ink.

Another method for changing the pressure when applying thermal energy to a thermal transfer material is to make at least one of a heating element having a heating element on its surface or a platen that supports a recording medium convex (for example, spherical or cylindrical). ), and the maximum contact position between the thermal transfer material and the heating element, and the formation position of the heating element on the heating element, based on the manner of contact between the heating element and the platen through the thermal transfer material and the recording medium. The relative change in the contact pressure may be realized by relatively changing the contact pressure. Details of such a method of changing the pressure can be found in Japanese Patent Application No. 61-2468 previously proposed by the present inventors.
No. 9 can be referred to, and below, an example of a preferred embodiment of such a method of changing pressure will be explained in slightly more detail.

FIGS. 6(a) and (b) are schematic diagrams in the thickness direction of a thermal transfer material (the intermediate layer 3 is not shown) for explaining a preferred embodiment of the recording method using the thermal transfer material of the present invention. FIG.

In the embodiment shown in FIG. 6(a), a heating element 21a is provided near the tip, and has a convex surface that is a partially spherical surface or a partially cylindrical surface extending in the thickness direction of the drawing, and a part of the heating element 21a has a heating element 21a. The heating element 21a is placed on the recording medium 5 on the platen 23 while moving the almost rod-shaped thermal head 21 (the supporting structure thereof is not shown) in which the element 21b is formed by vapor deposition or the like in the direction of the arrow. The abutted thermal transfer material 1
00 on the support body 10 side and heat is applied thereto. In the embodiment of FIG. 6(a), the maximum contact position of the heating element 21a (the position on the heating element 21a that provides the maximum contact pressure to the support 10 when the thermal head 21 is stationary, This figure shows a case where the position where the convex surface of the thermal transfer material 1001 contacts the platen 23 via the recording medium 5) coincides with the mounting position of the heating element 21b. That is, the heat-sensitive transfer material 1oo includes a heating element 2.
1a and the recording medium 5 at point A (
at the maximum contact point), the heating element 21b of the thermal head 21
More thermal energy is applied, and after the thermal transfer material ioo and the recording medium 5 are separated, both the first ink layer 1 and the second ink layer 2 are transferred to the recording medium 5, and a recorded image 12 is formed.
a is formed. This is because the pressure applied from the thermal pad 2 to the thermal transfer material joo becomes high at point A when heat is applied. Incidentally, such a simultaneous transfer phenomenon of the first ink layer 1 and the second ink layer 2 occurs when the support 10 of the thermal transfer material 100 and the heating element 21a as shown in FIG.
Not only does the positional relationship in which the maximum contact position with the heating element 21b coincides with the mounting position of the heating element 21b, but also the positional relationship in which the mounting position of the heating element 21b is on the upstream side in the traveling direction of the thermal head 21 (i.e., D direction) (in any case, it is a position on the heating element 21a, for example, up to a position approximately 0.5 to 1 mm in front of the above-mentioned apparent maximum contact position). The reason why such a phenomenon occurs is that the platen 23 or the thermal transfer material 100 is
Due to the deformation of
This is due to a delay in heat transfer of the thermal energy applied to the thermal transfer material 100 to the interface or inside of the ink layer 1.2 due to b, or a heat storage effect.

FIG. 6(b) shows the same thermal transfer material 10 as in FIG. 6(a).
0 and when applying heat by the heating element 21b,
This shows a case where the heat application position is shifted downstream in the running direction of the heat generating member with respect to the maximum contact position of the heat generating element. That is, the thermal transfer material 100 has a heating element 21a.
Thermal energy is applied from the heating element 21b at a point 0 on the downstream side in the traveling direction of the thermal head 21 than point B, which is the maximum contact position. As a result, after the thermal transfer material 100 and the recording medium 5 are separated, the second ink layer 2 is selectively transferred to the recording medium 5, and a recorded image 2a is formed. This means that when heat is applied, the heating element 21 at the 0 point
This is because heat is applied from the heating element 21b in a state where the pressure applied to the thermal transfer material 100 from point a is lower than that at point B.

As explained above, the thermal transfer material 100 and the heating element 21a
By applying thermal energy to the thermal transfer material at different points of contact with the second ink layer 2 or the first ink layer and the second ink layer using the thermal transfer material as shown in FIG. It becomes possible to selectively transfer both layers of the ink layer to the recording medium.

In the above, the thermal head method, that is, the case where a thermal head is used as a patterned energy supply source, has been described as a typical embodiment of the present invention. As shown in FIG. 2, it is also possible to apply energy in a desired pattern to the heat-sensitive transfer material using a recording electrode 8i6 which is a needle-like or multi-stylus-like electrode. When this recording electrode is used, there is no need for cooling time for the dots that make up the recording electrode, so printing can be performed faster than with the thermal head method.
It also has the advantage of higher thermal efficiency than the thermal head method.

In this embodiment (recording electrode method), a conductive material is used as the support 10 or in addition to the thermal transfer ink layer 12, and the support 10 (or the thermal transfer ink layer 12) is transferred from the recording electrode 6. After that, there is a return electrode 7 which is in contact with the support 10 over a much larger area than the recording electrode 6.
As a result, Joule heat generation occurs in the support 10 (or even the thermal transfer ink layer 12) directly under the recording electrode 6 with a large current density, and the thermal transfer ink layer 12 melts or melts in a pattern. softened.

FIG. 7(b) shows another embodiment of the recording electrode system, in which a conductive layer 8 made of a vapor-deposited metal film is inserted between the support 10 and the first ink layer 1. A needle-shaped or spur-shaped return electrode 7a that reaches this conductive layer 8 is used as the return electrode. However, instead of this return electrode 7a, a large area return electrode 7 as explained in FIG. 2(a) may be used.

In any case, the recording electrode method shown in FIGS. 7(a) and 7(b) differs from the thermal head method only in the method of supplying patterned energy to melt or soften the ink layer, and the thermal transfer method of the present invention is different from the recording electrode method shown in FIGS. It is easy to understand that the materials can be used similarly.

For more details on the recording electrode method, see Japanese Patent Application Laid-open No. 1983
Reference can be made to JP-A-220795 and JP-A-58-12790. In order to make the support 10 and the thermal transferable ink layer 12 conductive, carbon black, titanium black, S
Conductive particles such as nO2, metal, etc. may be dispersed.

As described above, it is possible to obtain a two-color recorded image by using the thermal transfer material 100 of the present invention, employing a thermal head or a recording electrode as a source of thermal energy, and simply changing the pressing force against the support. can. However, since the heat supply source slides on the support at a relative speed, if the pressing force is large, the contact portion with the support will be subject to significant wear, which is disadvantageous for long-term use. Furthermore, if the pressing force is too small, the transfer of the ink to the recording medium will be poor, resulting in only an unclear transferred image. Therefore, it is preferable that the thermal transfer material of the present invention has the property of providing a clear two-color recorded image within a pressing force range that does not have the above-mentioned drawbacks and without significantly affecting wear of the heat supply source.

More specifically, in the thermal transfer material of the present invention, at the temperature at which the thermal transferable ink layer starts adhesion to the recording medium, the contact pressure is between 3 and 15 kg/cm2, and the second ink layer changes the transferred color tone. Providing both a transferred image and a transferred image of the tone transferred by both the first ink layer and the second ink layer (that is, within the above pressure range, a pressure such that Fl<F2 and F r
> F2) is preferable.

Increasing or lowering the pressure that is the "boundary" between the pressure where Fl < F and the pressure where F r > F 2 is
This can be achieved by adjusting the cohesive force of the intermediate layer 3 when heated. That is, as a means for this, it is sufficient to adjust the melt viscosity of the intermediate layer 3 at the adhesion start temperature, and more specifically, for example, adjustment of the softening temperature (the higher the temperature, the higher the boundary pressure), or adjustment of the molecular weight ( If the boundary pressure is increased, the boundary pressure will be higher). Furthermore, as another means, the boundary pressure can be changed by adjusting the compatibility between the intermediate layer 3 and the first ink layer or the second ink layer.

The pressure that the second ink calendar selectively transfers is 3Kg/c
If it is smaller than m', the transferred image made of the second ink layer obtained by transferring to the recording medium will have insufficient amount of transferred ink (because the adhesion between the second ink layer and the recording medium is insufficient). This tends to result in an unclear recorded image. On the other hand, the first and second
If the pressure at which the ink layer is transferred is greater than 15 kg/cm2, wear of the thermal head or recording electrode will increase, resulting in a crushed recorded image, or the running properties of the thermal transfer material will be unstable, resulting in poor transfer. The image becomes more likely to be distorted, and furthermore, the thermal transfer material becomes more likely to break when the transfer is stopped.

Here, the temperature at which the above-described thermally transferable ink layer starts adhesion to the recording medium is defined by the following. In other words, the "adhesion start temperature" means that the recording medium, plain paper with a smoothness of 120 seconds, is heated in a constant temperature bath maintained at a constant temperature.
Pressure is applied to the thermal transfer ink layer surface of the thermal transfer material at 2 Kg/
After adhering for 5 seconds at cm2, the thermal transfer material was peeled off from the recording medium at a peeling angle of 180° and a peeling speed of 10 mm/
This is the (R low) temperature of the constant temperature bath at which the transfer of the thermal transfer ink onto the recording medium is visually observed when the recording medium is peeled off at sec.

As a simple method, it is possible to determine the adhesion starting temperature by performing the above adhesion and peeling operations on a hot bench (trade name, manufactured by Reichert, West Germany) having a gradient in surface temperature. At this time, it is necessary to peel off the thermal transfer material from the temperature side of the temperature gradient.

Next, the structure of the thermal transfer material 100 of the present invention will be explained in detail. As shown in FIG. 1, the thermal transfer material 100 has a first ink layer 1 made of a colorant of a first tone and a binder on a support 10, and a layer between the first ink layer 1 and the second ink layer 2. An intermediate layer 3 disposed on the substrate 10 and a second ink layer 2 made of a colorant of a second tone and a binder are sequentially laminated from the support 10 side.

As the support 10, conventionally known films and papers can be used as they are, such as films of relatively heat-resistant plastics such as polyester, polycarbonate, triacetylcellulose, nylon, polyimide, aromatic polyamide, etc. Cellophane, parchment paper, condenser paper, etc. can be suitably used.

The thickness of the support 10 is preferably about 1 to 15 μm when considering a thermal head as a heat generating member during thermal transfer.

In addition, when using a thermal head, the surface of the support that comes into contact with the thermal head may be coated with silicone resin, fluororesin, polyimide resin, epoxy resin, phenol resin, melamine resin,
By providing a heat-resistant protective layer made of nitrocellulose or the like, the heat resistance of the support can be improved, or it is also possible to use a support material that could not be used conventionally.

Colorants include carbon black, nigrosine dye,
Lamp black, Sudan Black SM, Alkali Blue, First Yellow 01 Benzidine Yellow, Pigment
Yellow, India First Orange, Irgazine Red, Varanitroaniline Red, Toluidine Red, Carmine FB, Permanent Bordeaux FRR, Pigment Orange R1 Resole Red 20. Lake Red C10-Damine FB, Rhodamine B Lake, Methyl Violet B Lake, Phthalocyanine Blue,
Pigment Blue, Prilliant Green B1 Phthalocyanine Green, Oil Yellow GG, Zapon First Niro 100G.

Kayaset Y963, Kayaset YG, Sumiblast・
Niro〇G, Zapon First Orange RR5 Oil・
Scarlet, Sumiblast Orange G1 Orazole
Brown B1 Pomelo First Scarlet CG, Eisensbiron Red BEH, Oil Pink OP1 Victoria Blue F4R, First Gen Blue 5007,
All known dyes and pigments such as Sudan Blue and Oil Peacock Blue can be used. Others: copper powder,
Metal powder such as aluminum powder, mineral powder such as mica, etc. can be used. As other additives, surfactants, plasticizers, mineral oils, vegetable oils, etc. may be added as appropriate.

Examples of the binder material used for the first ink layer 1 and the second ink layer 2 and the material used for the intermediate layer 3 include natural minerals such as spermaceti, beeswax, lanolin, carnauba wax, candelilla wax, montan wax, and ceresin wax. Petroleum waxes such as wax, paraffin wax, and microcrystalline wax, oxidized waxes, ester waxes, low molecular weight polyethylene, synthetic waxes such as Fischer-Tropsch wax, and high-grade resin acids such as lauric acid, myristic acid, valmitic acid, stearic acid, and behenic acid. , higher alcohols such as stearyl alcohol and behenyl alcohol, esters such as sucrose fatty acid esters and sorbitan fatty acid esters, amides such as oleylamide, polyolefin resins, polyamide resins, polyester resins, epoxy resins, and polyurethane resins. , polyacrylic resin, polyvinyl chloride resin, cellulose resin, polyvinyl alcohol resin,
petroleum resin, phenolic resin, polystyrene resin,
Vinyl acetate resin, natural rubber, elastomers such as styrene-butadiene rubber, isoprene rubber, and chloroprene rubber, polyisobutylene, polybutene, and the like may be used alone or in combination of two or more.

The content of the colorant contained in the first ink layer 1 and the second ink layer 2 is preferably in the range of 2 to 80% with respect to the weight of the entire ink for each of the first ink layer and the second ink layer. .

Moreover, the thickness of the first ink layer 1, the second ink N2, and the intermediate calendar 3 is preferably in the range of 0.5 to 10 μm, and the thickness of the entire thermal transferable ink layer 12 is preferably in the range of 2 to 20 μm.

Furthermore, in the thermal transfer material of the present invention, in addition to the first ink layer 1, second ink layer 2, and intermediate layer 3, as shown in FIG. An adhesive layer 3a is provided for the purpose of controlling the adhesion, and an adhesive layer 3b is provided on the second ink layer 2 for the purpose of controlling the adhesion to the recording medium as shown in FIG. 9, as necessary. It may also be provided.

As mentioned above, in the thermal transfer material of the present invention, the first
It is preferable that the contact between the ink layer 1 and the second ink layer 2 increases the adhesive force between the two layers. This first and second
From the point of view of adhesive strength between the ink layers, these ink layers contain a binder having a similar composition in an amount of at least 20% (more preferably 40%) based on the total binder weight of each ink layer.
above) is desirable.

Here, the term "binder with similar composition" refers to a binder that is compatible with adhesive force development (preferably, a binder with a difference in solubility parameter of 1.0 or less).

More specifically, binders with similar compositions include:
Materials of the same type as exemplified as binder materials are used. For example, natural wax and synthetic wax are similar wax-based materials. Although resins are listed by system, for example, vinyl chloride resins, vinyl acetate resins, etc. are used as "vinyl resins" as binders with similar compositions.

From the point of view of increasing the adhesive force between the first and second ink layers, the softening temperatures of the first and second ink layers should be made close to each other (for example, the difference in softening temperature of both inks should be 50° C. or less);
Alternatively, the melt viscosity of both ink layers should be made close to each other (for example, at 120'e, the melt viscosity of the second ink layer should be approximately 1/4 to 4 times the melt viscosity of the first ink layer).
is preferred.

The above-mentioned preferable ranges of the binder composition, softening temperature, or melt viscosity are such that the above-mentioned improvement in adhesive strength can be achieved by satisfying any one of them, and it is not necessary that all of these are satisfied at the same time.

In this specification, the softening temperature refers to the apparent viscosity-temperature curve of the sample ink when the sample ink's apparent viscosity-temperature curve is determined using a Shimadzu flow tester CFT500 model under the conditions of a load of 10 kg and a temperature increase rate of 2°C/min. This refers to the temperature determined as the outflow starting temperature.

On the other hand, it is preferable for the intermediate layer 3 to cause cohesive failure within the layer before the second ink layer at low pressure.
The softening temperature of the second ink layer is desirably lower than that of the second ink layer (furthermore, lower by 10° C. or more).

The softening temperature of the second ink layer 2 is preferably in the range of 60°C to 120°C. If the softening temperature is lower than 60°C, the storage stability of the thermal transfer material will be poor, and if it is higher than 120°C, a large amount of thermal energy will be required during printing. must be given, resulting in poor sensitivity.

The first ink layer 1 or the second ink layer 2 when the adhesive layer 3b is provided may be adhesive at room temperature, or may have an extremely high softening temperature or may have no softening temperature.

On the other hand, it is preferable that the adhesive layer 3b, or the second ink layer 2 when no adhesive layer 3b is provided, firmly adheres to the recording medium when at least one of heat or pressure is applied. The layer 3b or the second ink layer 2 contains a heat-sensitive adhesive material or a pressure-sensitive adhesive material (preferably 5 to 9 parts per 100 parts of the total binder component).
It is preferable to contain about 0 parts, more preferably about 10 to 70 parts.

These specific materials are listed below.

Examples of heat-sensitive adhesive materials include polyolefin resins such as ethylene-vinyl acetate copolymers and ethylene-acrylic acid copolymers, polyamide resins, polyester resins, epoxy resins, polyurethane resins, acrylic resins, and polychlorinated resins. Vinyl resins, vinyl acetate resins such as vinyl acetate-ethylene copolymers, petroleum resins, phenolic resins, melamine resins, urea resins, polystyrene resins, styrene-butadiene rubber, isoprene rubber, and other elastomers. Can be used.

Pressure-sensitive adhesive materials include natural rubber, chloroprene rubber, synthetic isoprene rubber, styrene-butadiene rubber, nitrile-butadiene rubber, polyisobutylene rubber, styrene-isoprene or styrene-butadiene block copolymer, polyvinyl ether, polyacrylic ester, or Elastomers such as copolymers thereof can be used.

Further, the above heat-sensitive or pressure-sensitive adhesive material may be mixed with a tackifying substance such as an oil-soluble phenol resin, a plasticizer such as mineral oil or lanolin, and other anti-plastic agents.

As mentioned above, the intermediate layer 3 is preferably a layer that causes cohesive failure within it when heat is applied, but for example, the intermediate layer 3 is made of a material with good releasability (silicone resin, etc.). It is also possible to configure 3.

In manufacturing the thermal transfer recording medium of the present invention, a coating solution is prepared by mixing the materials constituting each of the layers described above with an organic solvent that dissolves a binder such as methyl ethyl ketone, xylene, or tetrahydrofuran. It may be applied sequentially.

Alternatively, after mixing the materials constituting each layer, they may be heated and melted, and a so-called hot melt coating may be performed in the molten state.

Furthermore, the materials constituting each layer may be mixed and coated as an aqueous emulsion by adding a dispersant such as a surfactant, or each layer may be coated using a different method using these methods. It is also possible.

The planar shape of the thermal transfer material used in the present invention is not particularly limited, but it is generally used in the form of a typewriter ribbon or a wide tape used in line printers.

As described above, according to the present invention, it is possible to create a two-color recorded image by simply changing the pressure applied from a heating element to a support, etc. when thermal energy is supplied. A thermal transfer material is provided.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Dai JC Fresh Ink 1> Both the liquid amount and the softening point indicate the values for the solid content. ) Ink 1 was prepared by thoroughly mixing each component of the above formulation.

This was coated on a 6 μm thick polyethylene terephthalate film support (hereinafter referred to as rPETJ) and heated at 70°C.
This was dried to form a first ink layer with a thickness of 2.5 μm.

Ink 2> Coat on the layer and evaporate the water at 60℃ to a thickness of 1 μm.
An intermediate layer of m was formed.

Ink 3> was coated and water was evaporated at 60° C. to form a second ink layer with a thickness of 3 μm to obtain a thermal transfer material (I).

A thermal transfer material (
n) was obtained.

Example 3 A thermal transfer material (
+11).

A first ink layer with a thickness of 2.5 μm is formed using the ink 6>, an intermediate layer with a thickness of 1 μm is formed using the ink 4, and a second layer with a thickness of 3 μm is formed with the ink 7 having the above formulation. An ink layer was formed to obtain a thermal transfer material (IV).

A first ink layer (2.5 μm thick) was formed using the AJC ink 6,
An intermediate layer (1 μm thick) was formed using ink 5, and a second ink layer (3 μm thick) was formed using ink 7 in the same manner as in Example 4 to obtain a thermal transfer material (V).

Ink 8> An adhesive layer 3a (Fig. 8) having a thickness of 1 μm was formed using 90 parts of polyethylene monoxide aqueous dispersion, and ink 9
A first ink layer (2.5 μm thick) was formed using ink 5, an intermediate layer (1 μm thick) was formed using ink 5, and a second ink layer (3 μm thick) was formed using ink 10 in the same manner as in Example 1. A thermal transfer material (Vl) was obtained.

A thermal transfer material (■) was obtained in the same manner as in Example 1, except that L. Ink 11> 11 was used and the intermediate layer was formed at a drying temperature of 50°C.

A thermal transfer material (■) was obtained in the same manner as in Example 6, except that the intermediate layer was formed using Ink 12>12.

Using the thermal transfer materials (I) to (■) obtained as described above, thermal transfer recording was carried out under the following conditions.

Printing was performed using an English typewriter (Typestar 6 manufactured by Canon Inc.). The thermal head is shown in Figure 6(a).
, a heating element 2 with a width of 140 μm is placed 100 μm backward (in the opposite direction to the arrow direction) from the top of the heating element 21a having the shape shown in (b) (partial spherical shape with a radius of curvature of 2 mm).
1t), and the pressing angle θ of the head was O.
It was modified to be variable up to ~5°. Also, heating element 2
The distance from the center of 1b to the thermal head end 21C was 380 μm.

The pressing angle (θ) of the head is 5° when the pressure is high, and the pressing angle θ is 2° when the pressure is low, and the smoothness is 6.
Printing was carried out on high-quality paper of 0 seconds.

The adhesion start temperature of the obtained thermal transfer material, the pressure at which the second ink layer selectively transfers at the adhesion start temperature, and the first
The pressure at which both the ink layer and the second ink layer are transferred is
It was as shown in the table below. Furthermore, the color tone of the transferred image when actually printed was as shown in the table below.

Furthermore, in the thermal transfer material (■) of Reference Example 1, when the pressing angle of the thermal head was set to Oo, a blue printed image was obtained. However, this thermal transfer material (■) was heated to 60°C.
After being left in an atmospheric dryer for 5 hours and left at room temperature, printing was performed again at a pressing angle of 0°, resulting in an unclear blue printed image with black ink transfer observed.

In addition, in the thermal transfer material (■) of Reference Example 2, the torsion coil spring that governs the pressing force of the thermal head was changed from a spring constant of 8 Kg/m mO to 16 Kg/mm (while keeping the "free angle of the arm" constant). When printing was performed instead of a paper, blue printing was obtained at a pressing angle of 2 degrees and black printing was obtained at 5 degrees, but the thermal transfer material ribbon running became extremely unstable and the obtained printing was distorted. It became. Furthermore, a sticking phenomenon between the thermal transfer material and the thermal head was observed, often leading to ribbon breakage, and such a printing method was impractical.

[Brief explanation of the drawing]

Figures 1, 8 and 9 are schematic cross-sectional views in the thickness direction showing examples of the layer structure of the thermal transfer material of Wood's invention, respectively, and Figure 2 shows the relationship between the pressure when thermal energy is supplied and the adhesive force between each layer. FIGS. 3 and 4 are schematic cross-sectional views for explaining the state changes of the ink layer and the intermediate layer under pressure, and FIGS. 5 (a) to (c) and 6 (a) ), (b)
7(a) and 7(b) are schematic side views or schematic cross-sectional views for explaining the structure and operation example of the thermal head section to achieve pressure changes, and FIGS. 7(a) and 7(b) use energy application means other than the thermal head method. FIG. 3 is a schematic cross-sectional view showing a case. 1... First ink layer 2... Second ink layer 3... Intermediate layer 3a... Adhesive layer 4... Thermal head 4a... Heat generating element 5... Recording medium 6... -Recording electrode 7.7a...Return electrode 8...Conductive layer 10...Support 12...Thermal transferable ink layer 100...Thermal transfer material IL2! 11m Figure 1 Figure 2 Pl Pa, Pressure Figure 3 Figure 4 Figure 5 ttq Figure 6 (a) (b) Figure 7 (a)

Claims (1)

[Claims] 1. A thermally transferable ink layer consisting of at least a first ink layer, an intermediate layer, and a second ink layer having a different color tone from the first ink layer is provided on the support from the support side. and the adhesive force between the support and the first ink layer (F_1) and the adhesive force between the first ink layer and the second ink layer (F_2) supply thermal energy to the thermally transferable ink layer. A thermal transfer material characterized in that F_1<F_2 when the contact pressure is relatively large, and F_1>F_2 when the contact pressure is relatively small. 2. At the temperature at which the thermally transferable ink layer starts adhesion to the recording medium, a contact pressure corresponding to F_1<F_2, and F
The contact pressure corresponding to _1>F_2 is both 3 to 15
The thermal transfer material according to claim 1, which is within the range of Kg/cm^2.